JP2938564B2 - Fuel cut-off device for fuel tank - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel cutoff device for a fuel tank mounted on a vehicle such as an automobile.

2. Description of the Related Art Some fuel tanks for automobiles are provided with a fuel cut-off device so that fuel in the tank body does not flow out due to inclination of the automobile or the like. Generally, this fuel cutoff device has a casing 3 provided with a gas discharge hole 2 communicating with an evaporative tube 1 at an upper portion in a tank body 4 as shown in FIG. The structure is such that a float 5 for closing the valve seat 2a at the end of the discharge hole 2 is housed therein, and the fuel A flows into the casing 3 due to the fluctuation of the fuel level indicated by E and F in FIG. When the float 5 floats, the valve seat 2a
To prevent the fuel A from flowing out through the evaporative tube 1 to the outside.

However, in the case of such a fuel shut-off device, the float 5 closes the valve seat 2a due to the fluctuation of the fuel level in the tank main body 4, and in this state, when the gas pressure in the tank main body 4 increases, the inside of the casing 3 Even after the fuel A flows out, the float 5 may be attracted to the valve seat 2a and become stuck, that is, a so-called stick phenomenon may occur. Therefore, the float weight is increased or the like.

For this reason, conventionally, as shown in FIG.
A valve seat 6 having a donut shape is provided at a portion facing the gas discharge hole 2 of the first embodiment, and the valve seat 6 is movably and elastically held through a spring 7 and a cylindrical valve seat guide 8, while a casing is provided. A stopper 9 for restricting the closing stroke of the float 5 is provided on the lower surface of the upper wall of the float 3 or on the upper surface of the float 5, and when the gas pressure in the tank body rises while the float 5 closes the valve seat 6. In the state where the stroke of the float 5 is restricted, the valve seat 6 receives gas pressure in the tank body and is displaced to the valve opening position, whereby a stick of the float 5 is avoided. Have been.

This similar structure is shown, for example, in Japanese Patent Application No. 1-96658.

Problems to be Solved by the Invention In the case of the fuel shut-off device shown in FIG. 5, the float 5 and the valve seat 6 are guided on the inner peripheral surfaces of the casing 3 and the valve seat guide 8, respectively, whereby the relative positions of the float 5 and the valve seat 6 are always maintained. However, when the gap between the valve seat guide 8 and the valve seat 6 is reduced to a certain range or more in order to increase the relative positional accuracy between the valve seat 6 and the float 5, However, there is a concern that the outer peripheral corner of the valve seat 6 may interfere with the valve seat guide 8 only by slightly inclining when the valve seat 6 rises, thereby hindering the smooth operation of the valve seat 6.
The production is performed with extremely high precision, which causes an increase in production cost.

Therefore, the present invention is to provide a fuel shut-off device for a fuel tank that can increase the relative positional accuracy between the valve seat and the float without hindering the smooth lifting and lowering operation of the valve seat.

Means for Solving the Problems The present invention, as means for solving the above-mentioned problems,
While the valve seat closed by the floating of the float accommodated in the casing is movably and elastically held at a portion facing the gas exhaust hole of the casing disposed in the tank body, the casing or the float is provided with the float. In a fuel shut-off device for a fuel tank, a stopper for regulating a closing stroke is provided, and when the internal pressure of the tank body rises to a predetermined value or more, the valve seat is displaced to a valve opening position where the valve seat is not in contact with the float. A guide shaft that is slidably fitted to the shaft core of the valve seat protrudes from the casing.

If the internal pressure of the tank body rises while the float floats and closes the valve seat, the float may remain adsorbed to the valve seat even after fuel flows out of the casing. When the internal pressure further rises and reaches a set value, the valve seat receives the internal pressure of the tank main body in a state where the closing movement stroke is regulated by the stopper, and is displaced to the valve separating position while sliding on the guide shaft. In addition, since the valve seat is guided by the guide shaft at the shaft center portion, there is no obstruction of the elevating operation due to the inclination.

Embodiment An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 10 denotes a casing of a fuel shut-off device formed of a resin material. The casing 10 is disposed on an upper portion of the tank body 4 and has an outlet 11 connected to the evaporator tube 1 at an upper end thereof. Is extended,
The evaporated fuel gas generated in the tank body 4 is guided from the gas discharge hole 2 of the outlet 11 to a canister (not shown) via the evaporative tube 1. Also,
Communication holes 12 and 13 are formed in the side wall and the lower wall of the casing 10, respectively. When the fuel level in the tank body 4 fluctuates when the vehicle turns or leans, the tank body 4 passes through the communication holes 12 and 13.
The internal fuel flows into the casing 10.

Further, the interior of the casing 10 is defined by upper and lower chambers by a wall provided with an opening 14, a valve seat 15 in the upper chamber 10a, and a spring 16 and 17 in the lower chamber 10b by the float 5, respectively. It is accommodated in a state where it can be elastically displaced through the intermediary. In addition, the valve seat 15 is thereby provided with the gas discharge holes 2.
Is movably and elastically held by the casing 10 in the upper room 10a facing the front. Also, 18 is the room of casing 10
10b is a stopper protruding from the lower surface of the upper wall. The stopper 18 comes into contact with the upper surface of the float 5 to regulate the amount of upward displacement of the float 5, that is, its closing stroke. .

The float 5 has a protruding seal portion 19 in the center of the upper surface, and when fuel flows into the casing 10, it rises by its own buoyancy while being guided by the side wall (of the room 10b) of the casing 10, and The opening 19 of the valve seat 15 is closed by the portion 19.

The valve seat 15 has an outer shape having small diameter portions 15b and 15c on both upper and lower sides of a large diameter portion 15a as shown in FIGS. In the state where it is inserted and set in the room 10a of the casing 10, the large diameter portion 15a
The spring 16 is in contact with the upper surface of the spring. In the valve seat 15, a through hole 21 is formed in a shaft core portion, and a horizontal passage 22 is formed orthogonally to an intermediate portion of the through hole 21, and the intermediate portion of the through hole 21 and the valve seat 15 are formed. The upper surface of the large-diameter portion 15a communicates with the horizontal passage 22. The lower end of the through hole 21 is the opening 20 closed by the float 5.

On the other hand, on the upper wall of the room 10a of the casing 10, a guide shaft 23 having a predetermined length is provided so as to protrude downward.
Are slidably fitted. This guide shaft
23 and the through-hole 21 are formed with almost no gap within a range where they can slide with each other.
15 lifting and lowering operations are performed with high accuracy and without tilting. The tip of the guide shaft 23 is a valve seat.
Although the valve seat 15 is located above the horizontal passage 22 in a state in which the horizontal passage 22 is lowered, when the valve seat 15 is raised, the valve seat 15 is lowered relative to the horizontal passage 22 so as to cut off the communication between the opening 20 and the horizontal passage 22. Has become.

In the above-described configuration, in a normal state in which the fuel level in the tank body 4 does not fluctuate, since the float 5 is lowered by its own weight, the evaporated fuel gas generated in the tank body 4 cannot be removed from the valve seat 15. The gas is discharged to the outside through the gas discharge hole 2 and the evaporator tube 1 in order.

Then, when fuel flows into the casing 10 due to a change in the fuel level in the tank body 4 from this state, the float 5 floats and the seal portion 19 closes the opening 20 of the valve seat 15. As a result, the fuel is prevented from flowing out through the gas discharge holes 2 to the outside.

If the gas pressure in the tank body 4 increases in this state, the float 5 may remain adsorbed on the valve seat 15 even after the fuel returns from the casing 10 into the tank body 4. Since the gas pressure inside acts on the lower surface of the large diameter portion 15a of the valve seat 15 through the opening 14,
When the gas pressure in the tank body 4 becomes higher than the set value, the valve seat 15 rises due to the gas pressure while the upward displacement of the float 5 is restricted by the stopper 18, whereby the opening 20 of the valve seat 15 is opened. The float 5 stick is avoided. At this time, the valve seat 15 is guided by the guide shaft 23 and rises.When the valve seat 15 rises to a certain extent, the tip of the guide shaft 23 is positioned below the horizontal passage 22 to establish communication between the opening 20 and the horizontal passage. The pressure in the space B between the tip of the guide shaft 23 and the seal portion 19 of the float 5 in the through hole 21 gradually increases as the valve seat 15 rises. Therefore, the difference between the gas pressure in the tank body 4 and the pressure in the space B gradually decreases, and the stick of the float 5 can be released more easily.

In the fuel shut-off device according to the present invention, since the valve seat 15 is accurately positioned on the guide shaft 23 at the axis thereof, the relative position between the float 5 positioned on the side wall of the float 10 and the valve seat 15 is determined. Accuracy is greatly improved. For this reason, the valve seat 15 can operate smoothly without being caught or the like, and the valve seat 15 and the float 5 can always be stably contacted.

Effect of the Invention As described above, according to the present invention, since the guide shaft that is slidably fitted to the shaft core of the valve seat protrudes from the casing, a smooth lifting operation of the valve seat is ensured. Strict positioning of the valve seat can be performed, and the relative positional accuracy between the valve seat and the float can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part of the embodiment, FIG. 3 is an exploded perspective view of the main part of the embodiment, and FIG. FIG. 5 is a cross-sectional view showing another conventional technique. 2 ... gas exhaust hole, 4 ... tank body, 5 ... float, 10 ... casing, 15 ... valve seat, 18 ... stopper, 23 ... guide shaft.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-274622 (JP, A) JP-A-4-201719 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F02M 37/00 301 B60K 15/00

Claims (1)

(57) [Claims] A valve seat closed by floating of a float accommodated in a casing is movably and elastically held at a portion facing a gas discharge hole of a casing disposed in a tank body, while the casing or the casing is closed. A fuel for a fuel tank is provided in which a float is provided with a stopper for regulating a closing stroke of the float, and when the internal pressure of the tank body rises to a predetermined value or more, the valve seat is displaced to a valve opening position where the float is not in contact with the float. A fuel cut-off device for a fuel tank, wherein a guide shaft slidably fitted to a shaft core of a valve seat is protruded from the casing.