Motor vehicle tank with filling tube vent

In the particular embodiments described in the specification, a motor vehicle tank has a filling tube with a vent orifice connected to a device for adsorbing fuel vapors and a sealing arrangement including two annular lips spaced on opposite sides of the vent orifice and arranged to sealingly engage a filling pump nozzle to seal off the orifice from the fuel tank and from the atmosphere during filling of the tank.

BACKGROUND OF THE INVENTION 
This invention relates to motor vehicle tanks having a filling vent in a 
tank filling neck. 
Modern motor vehicle tanks for liquid fuels have leakproof tank filler caps 
and are provided with filling tube vents to avoid emission of vapors from 
the motor vehicle tank. The filling tube vents are usually connected to an 
activated-charcoal filter, the function of which is to adsorb fuel vapors 
produced within the motor vehicle tank, particularly when the motor 
vehicle is stationary, so that no fuel vapors escape from the motor 
vehicle tank into the atmosphere. During refuelling, the filling tube vent 
is normally closed or substantially closed so as not to saturate the 
activated-charcoal filter too heavily with fuel vapors and also to prevent 
complete filling of the tank. Despite closing of the vent, the fuel vapors 
produced in the tank normally do not escape into the atmosphere since 
modern pump nozzles are provided with a vapor extraction arrangement, or, 
in the United States, the vapors are temporarily stored in the 
activated-charcoal container. Preventing complete filling is necessary to 
make certain that the tank does not overflow if the fuel expands as a 
result of a high ambient temperature, the filling limit of the tank being 
determined by the filling tube vent line level. 
Closing of the filling tube vent of the tank during refuelling is usually 
achieved by providing a valve in the filling tube neck near the filler 
cap. The valve is arranged as a tilt valve and is actuated by the tank 
filler cap, that is to say, it is opened when the tank filler cap is 
closed. By removing the tank filler cap, the tilt valve automatically 
assumes its closed position. A disadvantage of this arrangement is that 
the valve usually contains metals which have to be removed when the tank 
is recycled. In addition, the valve requires a relatively large space. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a motor vehicle tank with 
a filling tube vent which overcomes the disadvantages of the prior art. 
Another object of the present invention is to provide a motor vehicle tank 
having a filling tube vent valve arrangement which may be made entirely of 
plastic and which can be removed easily for recycling and requires only a 
small space. 
These and other objects of the invention are attained by providing a motor 
vehicle fuel tank with a filling tube having a vent which is arranged to 
be closed by introduction of a fuel pump nozzle into the filling tube of 
the tank. 
Thus, the motor vehicle tank of the invention has a tank filling tube in 
which a tank vent is located and, during refuelling, the tank vent is 
essentially closed, at least to the extent that a dynamic pressure is 
built up in the tank vent as a result of the fuel flowing into the tank. 
This closure is provided at least relative to the atmosphere, and usually 
the closure also is effective with respect to the tank interior. Because 
closing of the tank vent is effected by introduction of the pump nozzle 
into the tank filling tube, the automatic closing valve arrangements of 
the prior art are no longer necessary. Closing of the vent by the pump 
nozzle can take place, for example, by motion of a lever which is arranged 
in the tank filling tube and is pushed sideways by the pump nozzle. 
Advantageously, however, closure may be effected by a sealing lip which is 
located in the tank filling tube and which sealingly engages the outer 
surface of the pump nozzle when it is introduced so as to seal the tube 
relative to the atmosphere. For this purpose, the sealing lip preferably 
has an annular configuration which matches the diameter of the outer 
surface of the pump nozzle. Particularly simple closure is thereby 
achieved. In an especially advantageous embodiment, two such annular 
sealing lips, which are spaced from each other, are provided. Both sealing 
lips sealingly engage the pump nozzle so that an annular cavity between 
the sealing lips, which are connected to one another, is closed by the 
pump nozzle. The vent orifice of the tank filling tube vent is connected 
to this annular cavity so that, when the pump nozzle is introduced, the 
tank vent is closed and, when the pump nozzle is removed and the filling 
tube cap is in place the tank vent is open. As a result, during refuelling 
the tank vent and the tank filling tube itself are closed in a simple way. 
At the same time, however, tank-venting during refuelling can take place, 
for example, through the pump nozzle. 
In a preferred embodiment, the sealing lip or lips may be arranged on a 
sealing element, which can be of multi-part design, having dimensions such 
as to fit the tank filling tube so that it can simply be pushed into the 
tube and preferably locked therein. This allows simple manufacture and 
assembly of the filling tube vent for the tank. 
The invention also encompasses a motor vehicle tank with a tank filling 
tube which contains a receptacle, into which a sealing element having at 
least one, preferably two, sealing lips can be inserted, in order to 
effect the above-described closing of the filling tube vent. 
The invention also relates to the provision of a sealing element having at 
least one sealing lip, preferably two sealing lips, which sealingly engage 
a pump nozzle and which may be inserted into a tank filling tube having a 
tank vent in order to bring about the above-described closure.

DESCRIPTION OF PREFERRED EMBODIMENTS 
In a typical embodiment of the invention shown in the drawings, a 
connection line 6 for a tank service vent arrangement 20 is formed in a 
tank filling tube 5 which is connected, as shown in FIG. 2, to the bottom 
portion of a motor vehicle tank 18. The connection line 6 is connected to 
a hose which opens at its other end into the service vent 20 in the upper 
portion of the tank 18. As shown. in FIG. 1, the connection line 6 opens 
into an annular groove 7 which is closed off relative to the inside of the 
filling tube 5 by a sealing element 1. Formed around the circumference of 
the sealing element 1 are ventilation slots 4 through which fuel vapors 
can escape from the tank filling tube 5 into the annular groove 7 and from 
there through the connection line 6 and the hose into the upper portion of 
the tank 18 and vice-versa. 
Also formed in the sealing element 1, in front of and behind the 
ventilation slots 4, are a first sealing lip 2 and a second sealing lip 3 
which, during refuelling, sealingly engage the outer surface 8 of a pump 
nozzle 21. The ventilation slots 4 in the filling tube are thereby closed 
to the atmosphere and to the tank filling tube 5 so that the service vent 
20 is also closed from the tank filling tube 5. Since the hose from the 
upper portion of the tank interior 9 is closed at the same time, the fuel 
vapors displaced in the tank 18 during refuelling are discharged in a 
controlled manner through a refuelling vent 10. Moreover, the refuelling 
vent 10 is arranged in such a way that the tank 18 can be filled only up 
to a selected level 11 above which the fuel 19 may expand when there is an 
increase in temperature. The refuelling vent 10 is connected to the tank 
filling tube 5, to a check valve 12 and to a switching valve 13 which is 
switched by a tank filler cap (not shown) in such a way that the switching 
valve is open when the tank filler cap is removed and is closed when the 
tank filler cap is screwed in. The check valve 12 is connected at its 
other end to a pressure-holding valve 14 which is in turn connected to the 
outlet of the switching valve 13, to an adsorber 15 containing 
activated-charcoal and to the intake side of an internal combustion engine 
16. The pressure-holding valve 14 is open in both directions on the tank 
side i.e., toward the check valve 12, that is to say it opens in the event 
of either an underpressure or an overpressure in the tank 18. The other 
end of the pressure-holding valve 14, which is connected to the intake 
side of the engine 16, remains closed in the event of an underpressure at 
the intake side. 
This arrangement assures that, during refuelling, the service vent 20 is 
closed, so that the tank interior 9 is vented only through the refuelling 
vent 10 by way of the outlet 17 of the adsorber 15 which is open to the 
atmosphere. As soon as the tank 18 is refuelled up to the refuelling vent 
line 10, the fuel 19 rises in the tank filling tube 5 as far as the end of 
the pump nozzle 21, with the result that the refuelling operation is 
discontinued. By closing the tank filling tube 5, tank ventilation and 
venting takes place through the check valve 12 and the pressure holding 
valve 14. 
Although the invention has been described herein with reference to specific 
embodiments, many modifications and variations therein will readily occur 
to those skilled in the art. Accordingly, all such variations and 
modifications are included within the intended scope of the invention.