JPH06201068A - Fuel cut-off device for fuel tank - Google Patents

Abstract

PURPOSE:To impede a sticking phenomenon positively and minimize the absolute value of spring force dispersion by additionally providing a gas switching valve with a small spring force so as to obtain high reliability in valve opening operation at the time of gas pressure in a fuel tank reaching the specified rise value. CONSTITUTION:At the time of being in the evaporated fuel gas of a tank body T, the inside of the tank body T is communicated with a valve housing 1c through the communicating hole 3c of a float 3 and a valve hole 1e provided at the valve housing 1c of a casing 1. When the gas pressure of the tank body T rises abnormally, a gas switching valve 6 with relatively small spring force is opened to discharge the evaporated fuel gas to a canister F from an outlet 2, thus preventing the damage of the tank body T. When fuel liquid infiltrates into the casing 1, buoyancy acts upon the float 3, and a liquid stopper spring 5b with relatively large spring force pushes up a valve body 5a to close the valve hole 1e. The outflow of the fuel liquid R is thereby impeded, and if gas pressure rises in this state, the valve hole 1e is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel tank mounted on a vehicle such as an automobile. When the fuel tank is used by being attached to the tank body, the evaporated fuel gas generated in the tank body is stored in the tank. The fuel is shut off by discharging it from the main body to the canister to prevent an abnormal rise in the gas pressure in the tank main body (tank internal pressure), but to prevent the fuel liquid that fluctuates due to vehicle shaking etc. from leaking to the outside. Regarding the improvement of the device.

[0002]

2. Description of the Related Art As a fuel cutoff device for an automobile or the like, a device as shown in FIG. 4 (Japanese Utility Model Laid-Open No. 62-75278) is already known. When this happens, the tank body a
An exhaust hole d communicating with the evaporation tube c is provided in a casing b arranged in the upper part of the inside, and a float e floating by the inflow of the fuel liquid is stored in the casing b. When the fuel liquid level in the inside fluctuates and the fuel liquid flows into the casing b, the float e rises due to buoyancy, so that the seal part e1 provided on the upper surface of the float b closes the discharge hole d, The liquid is prevented from flowing out through the evaporation tube c. Here, f in the same figure shows the canister to which the evaporated fuel gas is sent through the evaporation tube c.

However, in the case of such a fuel cutoff device, the discharge hole d is caused by the buoyancy of the float e due to the fuel liquid.
However, if the gas pressure in the tank main body a increases due to the closed state, the float e keeps closing the discharge hole d. Then, the so-called stick phenomenon occurs. Therefore, in order to prevent such an undesired state, the weight of the float e is increased. However, this causes the fuel cutoff device to become unintentionally large and large. Become.

In the conventional example shown in FIG. 4, in order to solve such a problem, the relief valve g is provided in the casing b so that the float e closes the discharge hole d.
When the gas internal pressure in the tank body a becomes equal to or higher than the set value, the relief valve g is opened to allow the evaporated fuel gas in the tank body a to escape from the evaporation tube c, thereby eliminating the stick phenomenon. ing.

However, even in the above-mentioned conventional example, since the relief valve g is for avoiding the stick phenomenon of the float e, the valve opening pressure is, of course,
The pressure must be set lower than the pressure (stick pressure) at which the float e receives the gas internal pressure in the tank body a and strongly contacts the discharge hole. Therefore, if the stick pressure of the float e is set to be low, the opening pressure of the relief valve g is set to be low, and the stick pressure of the float e is eventually lowered to a desired value or more. Becomes difficult.

Therefore, even in the above-mentioned conventional example, it is impossible to fundamentally solve the problems such as the increase in size and the increase in weight of the float e. Therefore, Japanese Patent Application No. 3-14220 has already been proposed for a fuel cutoff device capable of fundamentally eliminating the occurrence of the stick phenomenon.
In this case, as clearly shown in FIG. 5, when the gas pressure of the tank main body a, that is, the tank internal pressure is increased by the evaporated fuel gas generated from the fuel liquid in the tank main body a, the spring h pushes it up, so that the casing b
The valve body m, which is in the protruding valve housing i and closes the valve opening k of the valve seat j opened at the upper end of the valve housing i, is pushed down, whereby the fuel vapor in the tank body a is evaporated. The gas is sequentially discharged from the inside of the valve housing i through the evaporation tube c through the communication hole e2 of the float e and the valve port k to the canister f.

Further, when the fuel liquid in the tank main body a enters the casing b as described above, the float e in which the guide channel n is fitted in the valve housing i exerts a buoyant force and becomes light, so that the spring h The valve element m completely closes the valve opening k by the spring force, and the outflow of the fuel liquid is blocked. Further, in the blocking state, even if the tank internal pressure in the tank main body a becomes large, the tank internal pressure exerts the action of pressing the valve body m against the spring force of the spring h, The stick phenomenon as described above has no room to occur, and the risk that the gas pressure rises while the float e keeps closing the valve opening k can be fundamentally eliminated.

[0008]

However, according to the above-mentioned proposal, although the stick phenomenon can surely be eliminated and it is effective, only one spring h is pushing up the valve body m. The spring force of the spring h not only causes the vaporized fuel gas to be released as the pressure rises, but also causes the fuel liquid to shut off when the fuel liquid enters the casing b, and Even when it rolls over when it is turned over, leakage of the fuel liquid is completely prevented.

As is known, in order to prevent the leakage of the fuel liquid at the time of the rollover, the spring h must have a considerably large pulsating force, while the outflow of the fuel liquid due to fluctuations is blocked. In this case, although a large amount of spring force is not required, it also requires a relatively large amount of spring force. On the other hand, in order to control the timely release of evaporated fuel gas, a spring with a considerably small spring force is required. Can be used, so if one tries to satisfy each of these three conditions with one spring,
After all, you have to use a spring with a fairly large spring force.

For this reason, when the above fuel cutoff device is used, a spring having a considerably large spring force is used. However, in the case of a spring, the spring force varies and, for example, the degree of variation is ± 10. %, 2 g if the spring force is about 10 g
While the amount of variation is only about 30 g, the variation of 30 g results in a variation of 6 g, and the absolute value becomes extremely large. As a result, when controlling the vaporized fuel gas, which requires only the spring having the smallest spring force, if a spring having a large spring force is used, it is difficult to perform desirable control due to the variation.

The present invention is intended to eliminate the defects of the conventional example as described above, and in the conventional example shown in FIG. 5, the spring h pushes up the valve element m, thereby the normal time valve. The valve opening k is not closed by the body m, but the spring h is pushed down by the weight of the float e, and the valve opening k is kept open by this. Therefore, the vaporized fuel gas in the tank main body a normally enters the valve housing n through the valve port k, but an umbrella valve that responds to the variation in the internal pressure of the vaporized fuel gas separately. A gas on-off valve formed by such means is provided to cope with an abnormal rise in the gas internal pressure.

As described above, the above gas on-off valve is dedicated to the control of the evaporated fuel gas, and the fuel liquid is the casing b.
When it enters the inside of the tank or at the time of rollover, another source of the spring corresponding to the above-mentioned spring h prevents the outflow of the fuel liquid, so that the tank in the tank main body due to the evaporated fuel gas in particular is prevented. With the internal pressure, the evaporated fuel gas can be controlled to open and close at a predetermined boost value at all times.
The purpose is to improve the reliability thereof, thereby helping to prevent a more desirable stick phenomenon, and achieving the reduction in weight and the reduction in size with high accuracy.

[0013]

In order to achieve the above object, the present invention provides a casing internally provided at an upper portion of a tank body and having a communication port, and a casing provided at a lower portion of the casing, which is provided outside the tank body. An outlet communicated with the canister via an evaporation tube and a float fitted in the casing so as to be able to move up and down, and the valve housing projecting upward from the axial center of the bottom wall of the casing has the float of the float. A guide cave that opens downward on the axis,
The float top plate portion, which is fitted so as to be able to move up and down, is provided directly above the guide channel, is provided with a communication hole and an operating protrusion projecting downward at the axial center, and this operating protrusion is attached to the valve housing. The valve seat of the valve seat provided at the upper end is loosely fitted, and a sluice valve port is formed in the sluice valve seat that divides the valve housing and the outlet, and between the sluice valve seat and the valve body internal to the valve housing, When the float is in the fuel liquid, the valve body is pushed down by contact with the above-mentioned actuating projection of the float in a normal state through a liquid stop spring for shutting off the fuel liquid. The spring force of the liquid stop spring is set so that the body closes the valve opening of the valve seat, and the gas valve opening / closing valve in which the generated evaporated fuel gas communicates with the partition valve seat through the partition valve opening. Of the fuel tank characterized in that It is intended to provide a charge blocking device.

[0014]

[Operation] When the inside of the tank main body has a normal tank pressure, the operating protrusion of the float pushes the valve element inside the valve housing against the spring force of the liquid stop spring,
Therefore, the communication hole of the float and the valve opening of the valve seat maintain the inside of the tank body and the inside of the valve housing in communication with each other. Is being applied.

Therefore, when the internal pressure of the gas becomes larger than a predetermined value due to the evaporated fuel gas in the tank body,
The gas on-off valve is opened, and the sluice valve port of the sluice valve seat connects the inside of the valve housing with the outlet, which causes the vaporized fuel gas to be released to the canister through the evaporation tube, which may cause abnormal pressure rise in the tank body. Prevent.

Next, if the fuel liquid in the tank body infiltrates into the casing through the communication port due to turning or fluctuation of the vehicle,
Buoyancy acts on the float, so it becomes lighter, and the force of the spring raises the float, which causes the valve body to close the valve opening of the valve seat. Ingress is blocked and there is no leakage of fuel liquid. Also, at the time of rollover as is known, the valve element is pushed downward by the spring force of the liquid stop spring, so the valve opening of the valve seat is blocked by the valve element, and the fuel is also removed at this time. The outflow of the liquid is kept in a blocked state.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to FIGS. 1A and 1B and FIGS. 2 and 3. As is known, a fuel cutoff device X according to the present invention is a tank main body in which a fuel liquid R is stored. At the upper part of T, it is attached via a bracket B and the evaporated fuel gas generated in the tank body T is
It can be discharged to the canister F outside the tank body T via the evaporation tube E, where FT is a filler tube and BT is a belt tube.

The fuel shut-off device X is composed of a casing 1 having a communication port 1a internally fixed to a top portion of a tank body T by a bracket B, and a lower portion of the casing 1.
The outlet 2 is provided under the bottom wall 1b, and the outlet 2 is communicated with the canister F outside the tank body T via the evaporation tube E as described above.

Further, there is a float 3 fitted in the casing 1 so as to be able to move up and down, and a cylindrical valve housing 1c projects upward from the axial center position of the bottom wall 1b of the casing 1. And the guide cavity 3a is opened downward at the axial center of the float 3.
Is fitted into the valve housing 1c so as to be able to move up and down. The float top plate portion 3b, which is provided directly above the guide cavity 3a, is provided with a communication hole 3c and an operating protrusion 3d that is provided at the center of the shaft and projects downward. It is loosely fitted in the valve opening 1e of the valve seat 1d provided at the upper end of the valve housing 1c.

Further, according to the present invention, a sluice valve seat 4a for partitioning the valve housing 1c and the outlet 2 is provided, and a sluice valve port 4b is opened in the sluice valve seat 4a and the sluice valve seat 4a and the valve housing. A liquid stop spring 5b for shutting off the fuel liquid R is interposed between the valve body 5a, which is a spherical body and the like, which is internally provided in 1c. Here, the spring force of the liquid stop spring 5b is
When the inside is in a normal state, the valve body 5a is pushed down by the operating protrusion 3d of the float 3, so that the communication hole 3
c, the valve opening 1e, and the inside of the valve housing 1c are in communication with each other, and when the float 3 is in the fuel liquid R and is receiving buoyancy, the valve body 5a has the valve opening 1e of the valve seat 1d.
Is set to close.

Further, in the present invention, the vaporized fuel gas generated in the tank body T is introduced into the valve housing 1c through the gate valve in the gate valve seat 4a having the gate valve 4b. There is provided a gas on-off valve 6 which operates so as to communicate with the inside of the outlet 2 freely. Here, as the gas opening / closing valve 6 shown in FIG. 1, a known umbrella valve is adopted, which is inserted into the shaft hole of the sluice valve seat 4a to prevent the retaining expansion 6a from squeezing the sluice valve seat 6a. 4a is swelled to the upper side, and the umbrella portion 6b is connected to the lower side of the sluice valve seat 4a. When the umbrella portion 6b is inverted due to the increased internal pressure of the evaporated fuel gas in the valve housing 1c, the evaporated fuel gas flows into the outlet 2 through the partition valve port 4b of the partition valve seat 4a. Become.

Here, an umbrella valve is used as the gas on-off valve 6, but a gas valve as shown in FIG. 2 may be used. In this case, the sluice valve port in the sluice valve seat 4a is used. A gas stop valve body 6c is disposed below 4b, and is pushed up by a gas stop spring 6d disposed below the stop valve body 6c. Due to the spring force of 6d, the gate valve opening 4
b is blocked.

Here, in the illustrated embodiment, a known negative pressure valve 7 is provided at the base portion of the outlet 2, which means that the gas internal pressure at the outlet 2 is the gas of the tank body T. When it becomes larger than the internal pressure,
The negative pressure valve body 7a resists the spring force of the negative pressure spring 7b,
The negative pressure valve port 7c is pushed down to be opened, whereby the tank body T and the inside of the outlet 2 communicate with each other via the discharge port 7d.

Since the present invention can be configured as described above, as understood from FIG. 1, when the inside of the tank body T is in a normal state, the valve body 5a has the valve port 1
e is not blocked, and the evaporated fuel gas in the tank body T is
It has entered into the valve housing 1c. At this time, when the tank internal pressure rises to a certain pressure, the gas opening / closing valve 6 is opened, and the evaporated fuel gas is discharged to the outlet 2-evaporation tube E-canister F through the valve port 4b, The inside of the tank body T will not be in an abnormally increased pressure state. At this time, as the gas on-off valve 6, it is possible to adopt a valve having a very small spring force, so that the dispersion of the spring force is also small, and a highly responsive open / close operation that responds to the rise and fall of the gas pressure is possible. Will be realized.

Next, when the fuel liquid R enters the casing 1 as described above, the buoyancy acts on the float 3 so that the valve body 5a closes the valve opening 1e by the spring force of the liquid stop spring 5b. The fuel liquid R in the tank body T is prevented from flowing into the valve housing 1c. And
Even if the gas pressure in the tank main body T rises due to the continuation of the blocking state, the gas internal pressure pushes down the float 3, so that the stick phenomenon as described above does not occur.

[0026]

INDUSTRIAL APPLICABILITY As described above, the present invention not only completely prevents the stick phenomenon from occurring and solves the problems such as an increase in the size of the float and an increase in weight, but also the valve body is pushed up by the liquid stop spring. Is opened without being closed in a normal state, and in this state, a separately provided gas opening / closing valve is used to release the vaporized fuel gas in a timely manner so that the tank internal pressure due to the gas in the tank body does not become excessive. Since the liquid stop spring is not involved in the adjustment of the tank internal pressure, and the adjustment can be entrusted only to the gas on-off valve, it is necessary to give the gas on-off valve a large spring force to prevent the outflow of the fuel liquid. As a result, it is possible to reduce the variation in the spring force of the gas on-off valve, so that the gas is always highly reliable at the desired gas internal pressure. It is possible to release the closing, of course it is also possible to improve the reliability for the outflow preventing fuel liquid during variation and rollover of the vehicle.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a fuel cutoff device for a fuel tank according to the present invention, in which (A) is a normal state and (B) is a fuel liquid immersion state.

FIG. 2 is a vertical cross-sectional front view of another embodiment of the fuel cutoff device of the above, in a normal state.

FIG. 3 is a schematic vertical sectional front view of a tank body to which the fuel cutoff device according to the present invention is attached.

FIG. 4 is a vertical cross-sectional front view showing a conventional example of a fuel cutoff device for a fuel tank.

FIG. 5 is a vertical sectional front view showing a fuel cutoff device which is another conventional example of a fuel tank.

[Explanation of symbols]

 1 Casing 1a Communication Port 1b Bottom Wall 1c Valve Housing 1d Valve Seat 1e Valve Port 2 Outlet 3 Float 3a Guide Cave 3b Float Top Plate 3c Communication Hole 3d Actuation Protrusion 4a Gate Valve Seat 4b Gate Valve Valve 5a Valve Spring 5b 6 Gas on-off valve E Evaporative tube F Canister R Fuel liquid T Tank body

Claims (1)

[Claims] 1. A casing, which is internally provided at an upper portion of a tank body and has a communication port, an outlet provided at a lower portion of the casing and communicated with a canister outside the tank body via an evaporation tube, and the inside of the casing. The valve housing projecting upward from the axis of the bottom wall of the casing is provided with a guide cavity that opens downward to the axis of the float.
The float top plate portion, which is fitted so as to be able to move up and down, is provided directly above the guide channel, is provided with a communication hole and an operating protrusion projecting downward at the axial center, and this operating protrusion is attached to the valve housing. The valve seat of the valve seat provided at the upper end is loosely fitted, and a sluice valve port is formed in the sluice valve seat that divides the valve housing and the outlet, and between the sluice valve seat and the valve body internal to the valve housing, When the float is in the fuel liquid, the valve body is pushed down by the contact with the above-mentioned actuating projection of the float in a normal state, with the liquid stop spring for shutting off the fuel liquid interposed. The spring force of the liquid stop spring is set so that the body closes the valve opening of the valve seat, and the gas valve opening / closing valve in which the generated evaporated fuel gas communicates with the partition valve seat through the partition valve opening. Of the fuel tank characterized in that Fee shut-off device.