Fillable tank with filler pipe retainer

A fillable tank is disclosed, which tank is adapted to cooperate with a filler pipe for conveying material into the tank. The tank comprises a tank wall and a filler pipe seat defining an opening through the tank wall, which opening is adapted to receive the filler pipe. The filler pipe seat comprises a frustro-conical shoulder to improve the retention of the filler pipe in the tank against pull-out forces. The smaller diameter end of the shoulder is inward of the larger diameter end which latter is integral with the tank wall. The frusto-conical shoulder comprises integral reinforcement ribs extending substantially longitudinally on the surface thereof. Optionally, the small diameter end of the shoulder may provide a radial surface adapted to bear against a radially outward extending annular bearing surface of the filler pipe to prevent pull-out of such filler pipe from the tank.

TECHNICAL FIELD 
This invention relates in general to a fillable tank adapted to cooperate 
with a filler pipe, which tank comprises a filler pipe seat for improving 
the retention of the filler pipe in the tank against pull-out forces. The 
invention is particularly applicable for use as a fuel tank and filler 
pipe assembly in a motor vehicle. 
According to known tank and filler pipe designs, a filler pipe is inserted 
into the tank through a resilient grommet at the tank wall, with or 
without a support bracket between the filler pipe and the tank wall. 
Typically, the filler pipe serves to receive a nozzle, for example the 
nozzle of a gasoline pump hose, to convey fuel or other material into the 
tank. In many applications, such as the fuel tank of a motor vehicle, it 
is important that the filler pipe be securely attached to the tank. That 
is, it is important that the engagement of the filler pipe to the tank be 
able to resist pull-out forces likely to be applied to the filler pipe 
during use in its intended environment. Where the tank wall comprises a 
plastic material, such as polyethylene or other thermoplastic or a 
thermoset plastic, means are required for securing the filler pipe against 
being pulled out from the tank. Such means should require simple assembly 
and provide good durability in use. 
A retainer for supporting and locating a fuel filler pipe relative to the 
fuel tank of a motor vehicle is disclosed in U.S. Pat. No. 4,377,301 to 
Craig et al, which patent is assigned to the assignee of the present 
invention, and the disclosure of which is incorporated herein by 
reference. 
It is a primary object of the present invention to provide a fillable tank 
comprising means for retaining a filler pipe in the tank wall. Other 
objects, features and advantages of the invention will become more 
apparent from the following detailed description thereof, and from the 
accompanying drawings illustrating the preferred embodiments of the 
invention. 
DISCLOSURE OF THE INVENTION 
According to the present invention, a fillable tank, for example the fuel 
tank of a motor vehicle, or other fillable tank adapted to cooperate with 
means comprising a filler pipe extending into the tank for purposes of 
admitting fuel or other matter into the tank, comprises a tank wall and a 
filler pipe seat defining a fill port, that is an opening through the tank 
wall adapted to receive the filling means The filler pipe seat comprises a 
substantially rigid frustro-conical shoulder extending about at least a 
major portion of the circumference of the fill port. The larger diameter 
end of such shoulder is integral with the tank wall and the smaller 
diameter end thereof protrudes into the tank. The shoulder comprises 
substantially longitudinally (i.e., axially) extending integral 
reinforcement ribs. The small diameter end of the shoulder, at which the 
fill port is located, optionally may provide a radial surface adapted to 
bear against a radially outward extending annular bearing surface of the 
filling means to prevent pull-out of the filler pipe from the tank. 
Fillable tanks comprising plastic material tank walls (e.g., high density 
blow-molded polyethylene) provided with a filler pipe seat comprising 
essentially an inverted cone with reinforcement ribs according to the 
invention are found to resist pull-out of the filler pipe from the tank 
against significantly greater pull-out forces than could be withstood by 
the tank wall without such filler pipe seat. While not wishing to be bound 
by theory, it presently is understood that upon application of pull-out 
forces to the filler pipe the filler pipe seat is caused to compress 
axially and radially inward toward the filler pipe and to disperse the 
pull-out forces to the surrounding tank wall largely in compression. 
Particularly plastic tank walls are known to be stronger or more 
structurally stable in compression than in tension. In any event it has 
been found that tank assemblies comprising filler pipe seats according to 
the present invention have significantly greater filler pipe pull-out 
resistance and, accordingly, are more durable than assemblies without such 
filler pipe seats.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to FIGS. 1-3, a fillable tank 5 according to the invention is 
seen to comprise a tank wall 10. A concavity (as viewed from outside the 
tank) formed by the tank wall defines filler pipe seat 12 comprising fi-l 
port 13 adapted to receive means for filling the tank, specifically, a 
filler pipe 14 in conjunct-on with an elastomeric tubular grommet 15. The 
filler pipe seat is seen to comprise a frustro-conical shoulder projecting 
into the tank from the tank wall, with which it is unitary. The filler 
pipe seat further comprises strengthening ribs 20 extending longitudinally 
between the large diameter end 21 of the fzustro-conical shoulder to the 
small diamelez end 16. The ribs can comprise rigid members inserted into 
the wall of the shoulder or attached to the surface thereof or, more 
preferably, can be formed simp1y as a thickenIng of the wall or an upset 
or dislocation of the wall of the shoulder. 
Referring particularly to FIG. 3, the grommet 15 is seen to receive 
coaxially filler pipe 14. Where the tank is to be used as a motor vehicle 
fuel tank, for example, the grommet should sealingly receive the filler 
pipe. To improve the seal between the grommet and the filler pipe, and/or 
to increase the resistance to axial dislocation of the filler pipe 
relative to the grommet (and, hence, relative to the tank), the outer 
surface of the grommet provides a circumferential recess 25 of 
substantially constant diameter adapted to receive a clamp, such as a hose 
clamp, to tighten the grommet about the filler pipe. According to 
preferred embodiments, to further improve resistance to axial dislocatin, 
the seal and/or resistance to axial dislocation, the filler pipe provides 
an upstanding bead or flange 26 circumferentially, optionally 
intermittently, which is received by corresponding inwardly opening 
circumferential recess 27 of the grommet. Regarding the engagement of the 
filler pipe seat by the grommet, the small diameter end 16 of the shoulder 
provides annular flange 17 which is adapted to be received by outwardly 
opening circumferential recess 18 of the grommet. Where a fluid tight seal 
is desired at the fill port, the flange 17 preferably is provided with 
machined surfaces 19 and 20 and recess 18 is closely toleranced to form a 
sealing engagement therewith. 
Referring now to FIGS. 4-7, there is shown a tank 105 according to another 
embodiment of the invention. Tank 105 comprises tank wall 110 and filler 
pipe seat 112 defining an opening i.e. fi11 pozt 114, through the tank 
wall, which opening is adapted to eceive a filler pipe. The filler pipe 
seat 112 is seen to comprise a frustro-conical shoulder projecting into 
the tank from the tank wall. The smaller diameter end 16 of the shoulder 
is seen to be inward of the larger diameter end 118 of the shoulder, which 
larger diameter end is integral with and, more preferably, unitary with 
the tank wall 110. The outer surface of the shoulder is seen to comprise 
integral, and more preferably, unitary reinforcement ribs 120 comprising 
wall sections which are relatively thicker than the wall sections between 
such reinforcement ribs. The small diameter end 116 of the shoulder has a 
radial surface 122 which can be rounded or flat, which surface is adapted 
to bear against the filler pipe to hold the filler pipe against being 
pulled-out from the tank. Thus, the radial surface of the shoulder is 
adapted to bear against, for example, a radially outward extending annular 
bearing surface of the filler pipe. Such filler pipe bearing surface can 
be provided as an intermittent or continuous upstanding circumferential 
bead or as a radially extending circumferential flange unitary with the 
filler pipe or, for example, as a grommet forming a friction fit around 
the filler pipe. Referring particularly to FIG. 9, tank 125 is seen to 
comprise a tank wall 130 and filler pipe seat 135 defining a fill port, 
i.e., an opening through the tank wall, which opening receives filler pipe 
140. The filler pipe is fitted with grommet 145 which bears against radial 
surface 150 of the small diameter end 155 of the filler pipe seat. For 
convenience of assembly, the filler pipe bearing surface can be 
circumferentia11y intermittent and the fill port can provide a 
corresponding key-way. Thus, the filler pipe could be inserted and then 
twisted about its axis to present axial dis1ocation of the filler pipe out 
of the tank. 
As seen in FIG. 6, the inside surface of filler pipe seat 112 forms a 
frustro-conical surface. 
Referring now to FIG. 8, an alternative embodiment is illustrated, wherein 
tank 160 comprises tank wall 162 and filler pipe seat 164. While the inner 
surface of the filler pipe seat in the embodiment of FIGS. 4-7 was seen to 
form a frustro-conical surface, in the alternative embodiment of FIG. 8 
the inner surface 166 of the filler pipe seat 164 is seen to form a 
cylindrical surface. 
A tank comprising a tank wall and filler pipe seat therein as described 
above can comprise any suitable material such as metal or plastic. It will 
be recognized, however, to be particularly advantageous for use in plastic 
tanks, especially plastic fuel tanks for motor vehicles, wherein enhanced 
resistance to axial dislocation of the filler pipe is particularly 
important. In any case, the tank material must be sufficiently strong for 
its intended use and resistant to chemical attack by the intended contents 
of the tank. For use as a motor vehicle fuel tank, for example, plastic 
material comprising in major part high density, high molecular weight 
polyethylene is known to the art. Suitable materials for the filler pipe 
also are well known and include, for examp1e, metal and plastic. The 
bearing surface of the filler pipe can be formed in the case of a metal 
filler pipe, for example, by stamping or by welding or otherwise attaching 
a flange about the filler pipe. In the case of a plastic filler pipe the 
bearing surface can be unitary with the filler pipe, for example as when 
formed during blow-molding of a filler pipe. The filler pipe bearing 
surface, as noted above, also can be provided as a grommet comprising 
rubber or other resilient material forming a friction fit about the filler 
pipe.