Note: Descriptions are shown in the official language in which they were submitted.
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TANK CAP
BACKGROUND OF THE INVENTION
1) Field of the Invention
The invention relates to a tank cap with a cap part and
with a filler neck for a refueling nozzle, wherein the filler
neck can be closed by the cap part via a rotary closure, and
with at least two seals arranged on the cap part and active
between the cap part and the filler neck.
2) Description of the Related Art
In order to make tank caps for fuel tanks of motor
vehicles liquidtight, it is common to arrange seals of
various shapes and cross sections between the filler neck and
the removable cap part. These seals are usually compressed by
bayonet or thread means on rotation of the cap part and
consequently bring about: a type of seal to prevent liquid
fuel from coming out. It is now known that, even if the seal
makes good contact, fuel vapors can still escape to the
outside as they diffuse through the seal. Recently, the level
of fuel emissions caused in this way has to an increasing
extent been drastically limited by statutory regulations. For
fuel caps, the permitted permeation quantity is to be
restricted to 3 milligrams of hydrocarbons per day (24
hours) Even with the most carefully designed seal, this
cannot be achieved.
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A tank cap which is designed in such a manner that this
limit value can be observed is described in applicant's
Austrian Utility Model Application GM 610/99. In this case, a
system comprising two seals is proposed for sealing the cap
part in relation to the filler neck, one of which lies
further in and the other further out relative to the filler
neck. The seal lying further out includes an elastomer with
high permeation resistance and is arranged in such a manner
in relation to the seal lying further in that only a narrow
gap remains between the two seals. This concept is highly
suitable for more than meeting future legal requirements.
However, the constructional embodiment described provides, in
the inside of the filler neck, sealing surfaces for the seals
which are exposed in such a manner that they can be touched
and thus damaged by the refueling nozzle as it is inserted,
which could impair the desired sealing function.
The object of the invention is to further optimize a
tank cap of the type referred to in the introduction with a
sealing system having at least two seals, and in particular,
to ensure that damage cannot be caused to the sealing
surfaces by the refueling nozzle.
SUMMARY OF THE INVENTION
According to the invention, the object is achieved by
virtue of the fact that the sealing surfaces on the neck are
in each case provided behind a raised region of a
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protuberance or the like and/or below at least one projection
or the like.
According to a preferred embodiment of the invention,
the seals are arranged on parts of the cap part which, for
opening and closing, are held in a non-rotational manner in
relation to the neck. The consequently smaller operating
forces during opening and closing increase convenience. The
seals are also subjected to less stress.
According to a further feature of the invention, the
projection(s) and the protuberance are formed on the neck
itself. A neck embodied thus can be manufactured easily by
injection-molding.
According to a preferred embodiment of the invention,
the projections are those parts of the anti-rotation
arrangement provided on the neck, as a result of which the
constructional complexity of the tank cap is reduced.
If the sealing surface is provided behind a raised edge
region of a protuberance running around on the neck, it is
designed in particular as a formation running around in a
groove-like manner. A sealing surface embodied thus cannot be
reached or touched by the filling pipe of a refueling nozzle.
In a tank cap embodied according to the invention, it is
particularly important that the seals make as good contact as
possible against the sealing surfaces on the neck. It is
therefore advantageous if the seals can be pressed against
these sealing surfaces in a spring-assisted manner.
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The associated constructional embodiment can be effected
in a simple manner in that the seal lying further in is
arranged on a sealing part which is mounted vertically,
counter to the force of at least one resilient element, on an
element of the cap part, which element can be rotated for
opening and closing.
According to the invention, the seal lying further out
is arranged on an intermediate ring which is arranged between
the sealing part and the element of the cap part which can be
rotated for opening and closing, and is mounted rotatably in
relation to the latter. A very expedient and functionally
reliable arrangement of the seal lying further out is thus
achieved.
In this connection, according to the invention, the at
least one resilient element acts on the intermediate ring as
well and thus, via the intermediate ring, presses the seal
lying further out against its sealing surface on the neck. In
this connection, the seal lying further out interacts with a
conical support surface on the upper side of the sealing
part. These configurations also bring about a very compact
embodiment of the components involved.
The compact and very expedient construction continues in
the configuration of the anti-rotation arrangement as well,
projections or the like formed on the outer circumferential
edge of the intermediate ring forming those parts of the
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anti-rotation arrangement interacting with the projections of
the neck.
BRIEF DESCRIPTION OF THE DRAWING
5 Other advantages of the present invention will be
readily appreciated as the same becomes better understood by
reference to the following detailed description when
considered in connection with the accompanying drawings
wherein:
Fig. 1 is a cross-sectional view of a cap according to
the invention in a vertical or longitudinal section, the left
half illustrating the closed state and the right half the
open state.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the following description, the term "vertical"
relates to the direction of the dot/dash line indicating the
longitudinal axis of the cap. The expressions "above" and
"below" relate to above and below in the illustration.
Fig. 1 shows the outer end region of a filler pipe 1
extending to a motor vehicle tank (not illustrated) and the
cap part 2 which can close the latter. The invention
envisages a special configuration and a special interaction
of the cap part 2 which can be closed by hand and a neck 3
accommodated in the inside of the outer end region of the
filler pipe 1.
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The cap part 2 includes an outer grip piece 4 and an
inner grip element 5 which is intended to be inserted into
the neck 3. The grip element 5 is overlapped by the grip
piece 4 at the side and is clipped in the usual manner or
otherwise connected to the latter. The grip piece 4 is at the
same time designed in such a manner that, when the cap part 2
has been put on, the grip piece 4 overlaps from the outside
the end of the filler pipe 1 with a circumferential edge
region. The neck 3 is fastened in the inside of the end
region of the filler pipe 1, being held by an inwardly
flanged edge la of the filler pipe 1 and a snap connection 6
which can be made in a conventional manner.
That part of the grip element 5 located inside the neck
3 when the cap part 2 has been put on is at least essentially
cyl indrical . To lock the cap part 2 on the neck 3, the grip
element 5 is provided on its outer side with locking lugs 8
which interact with a thread segment 7 on the upper end
region of the neck 3, so that the cap part 2 can be locked by
rotation in the manner of a bayonet closure. However, this
closure mechanism can also be embodied in another manner.
The grip element 5 is provided centrally on its
underside with a cylindrical extension 9 which has a diameter
which is comparatively small in relation to the remainder of
its diameter. The central extension 9 is provided on the
outside with a circumferential shoulder 9a, as a result of
which its end region is imparted a slightly greater diameter.
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On a central, vertically upright annular part 11 of a sealing
part 12, a circumferential support protuberance 10 is
provided on the inside, which overlaps the shoulder 9a from
above. Both between the annular part 11 and the underside of
the grip element 5 and between the central extension 9 and
the upper side of the essentially disk-shaped sealing part
12, some space remains for a relative movement, still to be
described, of the sealing part 12 in relation to the grip
element 5.
The sealing part 12 is supported resiliently in relation
to the grip element 5 radially outside the annular part 11.
To this end, an intermediate ring 13 essentially similar to a
circular ring is provided, which, radially outside the
central annular part 11, engages, by means of a guide
protuberance 13a running around in an annular manner on its
upper side, in a guide groove 5a running around on the
underside of the grip element 5, and is mounted there. A
groove-like recess l3b running around on the underside of the
intermediate ring 13 forms an abutment or a support
possibility for one end of a resilient element 14. Instead of
one resilient element 14, a number of spring elements can be
provided, in which case the recess running around can be
replaced by a number of hollows. The second end(s) of the
resilient element(s) 14 is or are supported in one or more
recess 12a of the sealing part 12. The resilient element(s)
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14 act(s) on the sealing part 12 in the vertical direction
away from the intermediate ring 13.
The intermediate ring 13, the sealing part 12 and the
seals 17, 18 arranged on these parts and still to be
described do not rotate with the grip piece 4 and the grip
element 5 during opening and closing of the cap part 2. This
is made possible by the relative movement between the annular
part 11 and the central extension 9 of the grip element 5 and
also the relative movemerit between the grip element 5 and the
intermediate ring 13 by means of the protuberance 13a
engaging in the guide groove 5a. In addition, an anti-
rotation arrangement acting between the intermediate ring 13
and the neck 3 is also provided. As indicated in the figure
of the drawing, projections 15 or the like can be provided as
an anti-rotation arrangement on the outer circumferential
edge region of the intermediate ring 13, which projections
form a type of toothing and interact and can be brought into
engagement with second projections 16 which are provided
circumferentially on the inside of the neck 3. The
appropriate engagement of the projections 15, 16 can be
ensured in a simple manner if the cap part 2 is to be brought
into a specific position in relation to the neck 3 for
insertion of the grip element S.
Of the seals 17, 1.8 mentioned above, the seal 17 is
arranged on the intermediate ring 13 and is consequently the
seal lying further above, and the seal 18 is arranged on the
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sealing part 12 and forms the seal lying further in. Both
seals 17, 18 are in particular preformed ring seals made of
an elastomer.
The seal 17 is held, for example squeezed, in a groove
13c formed on the underside of the intermediate ring 13, and
has a sealing lip 17a which interacts with a conical support
surface 12b which is formed on the upper side of a rim 12c
running around on the outside of the sealing part 12 and,
when the cap part 2 is closed, is pressed against an at least
essentially vertically running surface 19 on the inside of
the neck 3. A comparison of the two halves of the figure of
the drawing reveals that, when the cap part 2 is closed, the
distance between the support surface 12b and the intermediate
ring 13 is reduced somewhat under compression of the
resilient element 14, as a result of which the sealing lip
17a is pressed against the sealing surface 19. Moreover, the
sealing surface 19 is located just below the projections 16
of the neck 3 and consequently offset inwardly in relation to
these, so that a filling pipe of a refueling nozzle (not
drawn) cannot touch this region when inserted.
On the underside of the rim 12c of the sealing part 12,
which runs around in an annular manner, a groove 12d running
around is formed for receiving the second seal 18 which is
slightly more voluminous than the first seal 17. The seal 18
also has a sealing lip 18a which extends vertically when the
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cap part 2 is not closed. The sealing lip 18a interacts with
a protuberance 21 formed on the inside of the neck 3.
The protuberance 21 running around in the neck 3 has on
its upper side a sealing surface 20 running around in a
groove-like manner for the seal 18. The sealing surface 20 is
protected against contact with the filling pipe of the
refueling nozzle by the circumferential edge which is raised
on the inside. When the cap part 2 is closed, the sealing lip
18b slides along the inner flank of the edge onto its sealing
surface 20 and is pressed in there, as shown by a comparison
of the two halves of the figure of the drawing.
The resilient element 14 therefore ensures indirectly
that the two seals 17, 18 are pressed against their sealing
surfaces 19, 20. The sealing of the cap part 2 is
consequently brought about by the compression of the seals
17, 18 radially outwardly against their sealing surfaces 19,
on the neck 3. Since, as already mentioned, the seals 17,
18 are not co-rotated during the rotary movement for opening
or closing the cap part 2, they are subjected to considerably
20 less wear. Operation according to the invention - without co-
rotation of the seals 17, 18 - increases convenience owing to
reduced operating forces during opening and closing. The
position of the two sealing surfaces 19, 20 on the neck 3
moreover ensures that the filling pipe of the refueling
nozzle cannot damage them when it is inserted. Any possible
accumulation of fuel in the region of the sealing surface 20
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can be avoided by at least one drainage opening 20a being
provided in the protuberance 21.
The two seals 17, 18 are made from in particular an
elastomer which is resistant to fuel and has good cold
elasticity. The action of the sealing arrangement described
in the inner seal 18 holds back in particular liquid fuel.
Fuel vapors which pass by or diffuse through this seal are
stopped by the second seal 17 which is therefore preferably
designed so as to be especially vapor-impermeable. It is also
advantageous here if the region to be sealed by the second
seal 17 is kept very small.
The invention is not limited to the exemplary embodiment
illustrated. It is in particular possible, for example, to
arrange both sealing surfaces on the neck either behind
raised regions or below projecting regions or to reverse the
arrangements illustrated. The anti-rotation arrangement can
be effected in a different place and a different manner.
Combinations with further seals are also possible.
