JP2943284B2 - Fuel tank fuel leakage prevention device - Google Patents

Description

The present invention relates to a fuel leakage prevention device for a fuel tank.

b. Prior art As shown in FIG. 8, a rollover valve 3 is installed in the fuel tank 1 or the evaporative pipe 2 in order to prevent fuel leakage occurring when the fuel tank 1 is extremely inclined. When the valve body 4 is fixed to the orifice portion 5 for some reason as shown in FIG. 9, the rollover valve 3 is often provided with a relief valve 6 so that the pressure in the fuel tank 1 does not abnormally increase. This is because when the internal pressure of the fuel tank 1 rises abnormally, when the filler cap is removed at the time of refueling or the like, fuel is easily blown back from the filler port, or the fuel tank 1 is deformed or fuel leaks from the hose joint. There is a possibility.

 Next, the operation principle of the rollover valve will be described.

When the vehicle posture is normal, the air in the upper space of the fuel tank 1 is in communication with the canister that adsorbs the evaporated fuel through the orifice 5 of the rollover valve 3.

It is assumed that the fuel tank 1 is turned upside down for some reason as shown in FIG.

In this case, as shown in FIG. 11, the valve body 4 of the rollover valve 3 closes the orifice 5 to prevent the fuel from flowing out. At this time, a pressure obtained by adding the head difference: H and the pressure in the upper space of the fuel tank 1 to the relief valve 6 of the rollover valve 3: P ₀ (the maximum value of P ₀ is the check valve opening pressure P _c ): H + P ₀ (Max: H + P _c ) is applied. Since the valve opening pressure P _r of the relief valve 6 is set greater than H + P _c, the fuel leakage nor from the relief valve 6 (P _r> H +
P _c ). Related prior arts are JP-A-61-191427 and JP-A-63-41244.

c. Problems to be Solved by the Invention However, if there is a sudden rise in the outside temperature in this state, the pressure P _{0 in} the upper space of the fuel tank 1 rises (P ₀ → P _t ), and the head difference H opening pressure of the total relief valve 6: exceeds _{P r (P r <H +} P t), the fuel in the fuel tank 1 there is likely to flow out from the relief valve 6 to the fuel tank 1 outside.

An object of the present invention is to solve the above-mentioned problems and to provide a fuel leakage prevention device for a fuel tank that can prevent fuel leakage from the fuel tank.

d. Means for Solving the Problems To solve the above problems, the present invention provides an evaporative pipe for exhausting the fuel vapor in the fuel tank to the canister side,
In the fuel leakage prevention device for a fuel tank in which a rollover valve provided with a relief valve is provided in the evaporative pipe, the other ends of the first and second evaporative pipes each having one end connected between the canister of the evaporative pipe and the rollover valve. Are vertically suspended at the lower portions on both sides in the fuel tank. When the other end of the evaporative pipe is in the oil liquid, the other end of the evaporative pipe is closed in the middle of the first and second evaporative pipes, and the other end of the evaporative pipe is in the air. That is, an on-off valve that opens is provided.

e. Operation When the fuel tank is tilted or turned in the opposite direction, the tip of the first and / or second evaporative pipe is positioned in the air. As a result, the on-off valve provided on the first and / or second evaporative pipe is opened, and the pressure in the fuel tank is reduced to the atmospheric pressure. Thus, fuel leakage from the rollover valve is prevented.

f. Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, in which the same parts as those in FIG.

In FIG. 1, reference numeral 1 denotes a fuel tank of a vehicle, and reference numeral 3 denotes a rollover valve provided in the fuel tank 1.

The rollover valve 3 includes a ball type and a float type, and the illustrated example is a float type.

As shown in FIG. 2, the rollover valve 3 is normally opened because the weight (W) of the valve body 4 (float) and the spring force (F) of the spring 7 satisfy W> F. . Then, as shown in FIG. 3, when the axis of the rollover valve 3 is inclined (θ °), the axial force (W ′) becomes W ′ =
If cos θ · W, the rollover valve 3 is closed if it is tilted until W ′ <F. Also, when immersed in gasoline, the weight of the float becomes lighter, For this reason, if it is set so that w <F, the roll-over valve 3 is closed only by being immersed in gasoline without tilting.

This rollover valve 3 is connected to a main evaporative pipe 8 leading to a canister (not shown),
This main evaporation pipe 8 has a rollover valve 3
A first evaporative pipe 9 and a second evaporative pipe 10 which are open at lower portions on both sides in the fuel tank 1 are connected to each other. The first and second evaporation pipes 9 and 10 are provided with a solenoid valve 11 and a solenoid valve 12 on the way, respectively. The solenoid valve 11 and the solenoid valve 12 are operated by a thermistor 13 and a thermistor 14 which are provided near the first and second evaporative pipes 9 and 10, respectively. The solenoid valve 11 (solenoid valve 12) closes when the thermistor 13 (thermistor 14) is below the liquid level, and opens when the thermistor 13 (thermistor 14) enters the air.

Next, according to the fuel leakage prevention device having the above configuration, when the fuel tank 1 is turned upside down as shown in FIG.
The valve body 4 of the rollover valve 3 closes.

Then, since the thermistors 13 and 14 come out into the air, the solenoid valves 11 and 12 are opened. On the other hand, the upper space of the fuel tank 1 atmospheric pressure P _a, and the pressure applied to the relief valve 6 is _{H R1 + P a (<H} + P c) , and therefore the relief valve 6 remains closed.

Therefore, fuel does not leak through the rollover valve 3 and the evaporative pipes 9 and 10.

When the fuel tank 1 is in the horizontal state as shown in FIG. 5, the valve body 4 of the rollover valve 3 is urged by the spring 7 to close.

Since the thermistor 13 above the fuel tank 1 is in the air, the solenoid valve 11 opens. On the other hand, since the thermistor 14 at the lower part of the fuel tank 1 is below the liquid level, the solenoid valve
12 remains closed.

Since the upper space of the fuel tank 1 is atmospheric P _a, the pressure applied to the relief valve 6 remains _{H R2 + P a (<H} + P c) , and the relief valve 6 is closed.

Therefore, fuel does not leak from the fuel tank 1 through the rollover valve 3 and the evaporation pipes 9 and 10.

H _R2 + P _a <H + P _c < _Pr FIG. 6 shows a remaining amount warning light provided in the fuel tank 1. In this figure, a light bulb as a warning light and a thermistor 17 are connected in series to a power source 15 such as a battery. Things.

As shown in FIG. 7, the thermistor 17 has a characteristic that the resistance value decreases as the temperature increases. Therefore, in gasoline, the temperature is lowered because the liquid is cooled down, and the resistance value is increased. Therefore, the warning light 16 is off.

On the other hand, in air, the thermistor 17 itself generates heat and the temperature rises, and the resistance value decreases. When the resistance value becomes equal to or less than a certain value, a current flows and the warning light 16 is turned on.

g. Effects of the Invention As described above, the fuel leakage prevention device for a fuel tank according to the present invention can completely prevent fuel leakage when the fuel tank is turned upside down. In a vehicle with a remaining amount warning light for displaying the remaining amount of fuel by the thermistor, the thermistor can be used as it is, which is efficient.

[Brief description of the drawings]

FIG. 1 is a conceptual sectional view showing an embodiment of a fuel leakage prevention device for a fuel tank according to the present invention, FIG. 2 is a sectional view showing a rollover valve of FIG. 1, and FIG. FIG. 4 is a conceptual cross-sectional view showing a state in which the fuel tank is turned upside down;
FIG. 5 is a conceptual sectional view showing a state in which the fuel tank is turned sideways, FIG. 6 is a circuit diagram showing a remaining amount warning light, FIG. 7 is a diagram showing a characteristic curve of a thermistor, and FIG. FIG. 9 is a conceptual sectional view showing a fuel leakage prevention device for a tank, and FIG.
FIG. 10 is a sectional view showing the operation of the rollover valve, and FIG.
The figure is a conceptual sectional view showing a state where the fuel tank is upside down. DESCRIPTION OF SYMBOLS 1 ... Fuel tank, 3 ... Rollover valve, 4 ... Valve body, 5 ... Orifice, 6 ... Relief valve, 8 ... Main evaporative pipe, 9 ... 1st evaporative pipe, 10 ... 2nd evaporative pipe, 11, 12 ... Solenoid valve, 13,14 ... Thermistor.

Claims (1)

(57) [Claims] An evaporative pipe for exhausting fuel vapor from a fuel tank to a canister side is provided. A fuel leak prevention device for a fuel tank, wherein the evaporative pipe is provided with a rollover valve having a relief valve, the evaporative pipe includes a canister. The other ends of the first and second evaporative pipes, one ends of which are connected to a rollover valve, are provided vertically below both sides of the fuel tank.
A fuel leakage prevention device for a fuel tank, further comprising an opening / closing valve provided in the middle of the evaporative pipe to close when the other end of the evaporative pipe is in the oil liquid and to open when the other end of the evaporative pipe is in the air. .