Safety system for liquid fuel tank
View Patent ↗Fuel safety system, made of plastic, comprising a liquid fuel tank equipped with a fill tube provided with a guide for a delivery nozzle, which includes a sealing device, a normally-open float valve, for degassing and venting the tank, and a vapour breather pipe that also fixes the maximum level of liquid in the tank, the pipe connecting the top of this tank to a point located downstream of the sealing device and being completely located inside both the tank and the fill tube.
1. A safety system for a liquid fuel tank, comprising:
a) a fill tube terminating in a tank, the inlet orifice of the tube including a guide for a nozzle provided with a sealing device for sealing against the external environment;
b) a valve, mounted on the tank, capable of degassing the tank during an operation of filling with fuel, and also of venting during periods when the tank is in normal use; and
c) a vapour breather pipe that also fixes the maximum level of liquid fuel in the tank,
wherein the pipe emerges at one of its ends in the top of the tank, connects this top to the upper portion of the fill tube and emerges at its other end, at a point located downstream of the sealing device, on the side facing the tank, and in which the pipe is completely located inside both the tank and the fill tube.
2. The system according to claim 1 , wherein the pipe emerges in the top of the tank via a float valve.
3. The system according to claim 1 , wherein the valve has a float, said valve being normally open when filling the tank and during the periods of normal use of the tank, and wherein the float line of the float is set so that the valve is closed only in two circumstances, namely when the tank is inclined beyond a predetermined limit, or even completely upside down, and during a transient movement of the fuel, the amplitude of which exceeds a predetermined value.
4. The system according to claim 1 , wherein the sealing device comprises an annular seal having at least one circular lip made of a flexible elastomer and intended to bear on the circumference of the spout of the nozzle.
5. The system according to claim 4 , wherein the sealing device furthermore includes, downstream of the lip, a stopper that can open under the effect of the pressure caused by contact with the end of the spout of the nozzle.
6. The system according to claim 1 , which furthermore includes a safety valve which can open only towards the external atmosphere in the event of excessive overpressure in the tank and which brings the inside of the fill tube into communication with the external atmosphere in the vicinity of the nozzle.
7. The system according to claim 6 , wherein the safety valve is an annular lip made of elastomer that extends the sealing device upstream, on the side facing the inlet orifice of the tube.
8. The system according to claim 6 , wherein the safety valve is a non-return valve independent of the sealing system and located in the guide for the nozzle, near the latter.
9. The system according to claim 1 , wherein at least one external surface layer of the pipe is electrically conductive and wherein this pipe is connected via an electrical conductor to a metal earth of a vehicle on which the tank is mounted.
10. The system according to claim 1 , suited to nozzles that are not provided with fuel vapour suction systems, wherein the valve is connected to a canister filled with a material that absorbs the fuel vapour and wherein the volume of the canister, the size of the valve and the diameter of the pipe connecting the valve to the canister are designed so as to be capable of evacuating most of the volume of gas escaping from the tank during the filling operation.
11. The system according to claim 1 , wherein the outlet of the valve emerges in the external atmosphere without passing via a canister.