This invention relates to a fuel tank with air vent provision, for a motor vehicle,
Fuel tanks of motor vehicles (excepting, perhaps, two wheeler motor vehicles, such as, motorcycles) usually have fuel filling inlets at the sides of the tank, either on the left or on the right side of the tank, for easy accessibility while filling These inlets are fitted with caps for opening or closing the tanks and each such cap has an air vent provision in the form of a hole opening out to atmosphere, at one end, and to the interior of the tank at its other end. The air vent is

intended not only to maintain the air inside the tank at atmospheric pressure, but also to allow the unhindered flow of fuel to the engine without any air-locks.
However, the main drawback with the conventional air vent provision at the sides of the fuel tank is the tendency of fuel sloshing around in the tank, particularly when the vehicle is running on a bumpy road. In such a situation, the fuel inside the tank escapes through the vent in the fuel inlet cap, resulting in poor mileage and waste of fuel which is expensive.
It is therefore the main objective of this invention to prevent leakage of fuel through the air vent.

Conventionally, a spring loaded steel ball is provided within the tank to serve as a one-way valve for the air vent. This arrangement allows atmospheric air into the tank when the pressure within the tank is less than atmospheric; but does not allow air from within the tank to go out to atmosphere. Consequently, fuel inside the tank also cannot go out of the tank through the vent.
However the drawback with this arrangement is that the spring used is of low tension, since the pressure difference between the interior of the tank and atmosphere is not much. The low tension of the spring makes it possible sometimes to result in

misalignment of the spring and allow leakage of the fuel through the vent.
Another conventional arrangement consists of a rubber breather of helical configuration, having one hole open to the outer wall of the breather and another hole open to the inner wall. This allows only air to enter and prevents the fuel from escaping due to the helical path. However, this device is difficult to manufacture on a mass scale in view of its complex construction. Also, there is every possibility that the helical path may get blocked in manufacture or in use.
This invention seeks to do away with the disadvantages associated with the known fuel tank air vent devices and

therefore proposes a fuel tank with a venting arrangement which is both effective and simple in use.
This invention will now be described in further detail with reference to the accompanying drawing which illustrates, by way of example, and not by way of limitation, one of possible embodiments of the fuel tank proposed herein.
A fuel tank F has a fuel inlet at the side. The said inlet is fitted with a vent less cap C (that is, a cap without any air vent in it) for opening and closing the inlet.
A hollow tube T is located on the top of the tank body B, the lower end L of

the hollow tube communicating with the interior of the tank, while the upper end R of the said tube is situated above the said body, terminating in an orifice open to atmosphere.
A stopper S opens and closes the said orifice and this stopper is provided with an air vent at E which communicates with atmosphere as well as the interior of the tank.
It will thus be seen that leakage of fuel at the fuel inlet zone is not possible because the fuel inlet cap C has no air vent therein. Also, fuel leakage at the air vent at E will not be possible in cases of movement of the vehicle usually encountered on the road, because any sloshing of the fuel in the

tank during such movement cannot, in normal circumstances, be such as to result in the fuel being tossed up to the height of the orifice at E.
It will be appreciated that various other embodiments of this invention are possible without departing from the scope and ambit of this invention.

We Claim:
1.. A fuel tank with air vent provision for a motor vehicle, said tank having a fuel inlet fitted with a ventless cap for opening and closing the inlet; a hollow tube located on the top of the body of the tank the lower end of the hollow tube communicating with the interior of the tank, while the upper end of the said tube is situated above the said body, terminating in an orifice open to atmosphere; a stopper for opening and closing the said orifice, said stopper being provided with an air vent communicating with atmosphere as well as the interior of the tank.
2. A fuel tank as claimed in Claim 1

wherein the fuel inlet is provided at the side of the tank.
3.A fuel tank with air vent provision for a motor vehicle substantially as herein described with reference to, and as illustrated in, the accompanying drawing.