U.S. patent application number 15/676175 was filed with the patent office on 2017-11-30 for closure system.
The applicant listed for this patent is KAUTEX TEXTRON GMBH & CO. KG. Invention is credited to Hartmut WOLF.
Application Number | 20170341507 15/676175 |
Document ID | / |
Family ID | 46026762 |
Filed Date | 2017-11-30 |
United States Patent
Application |
20170341507 |
Kind Code |
A1 |
WOLF; Hartmut |
November 30, 2017 |
CLOSURE SYSTEM
Abstract
The invention relates to a closure system on a fuel tank (2) of
thermoplastics with barrier properties for hydrocarbons. The
closure system comprises at least one orifice (4), with a closure
cap (5) which closes the orifice (4) in a sealing manner and which
cooperates in a form-fitting manner with closure means provided at
the circumference of the orifice (4) and encloses at least one
first sealing means between it and a tank wall (3). The closure
system (1) according to the invention is distinguished in that the
tank wall is sealed in the region of the orifice (4) with at least
one second sealing means, which covers and/or shields a part of the
tank wall surfaces exposed to hydrocarbons.
Inventors: |
WOLF; Hartmut;
(Konigswinter, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KAUTEX TEXTRON GMBH & CO. KG |
Bonn |
|
DE |
|
|
Family ID: |
46026762 |
Appl. No.: |
15/676175 |
Filed: |
August 14, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14128149 |
Mar 31, 2014 |
9731595 |
|
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PCT/EP12/01812 |
Apr 27, 2012 |
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15676175 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60K 2015/0438 20130101;
B60K 2015/03046 20130101; B60K 15/04 20130101; B60K 2015/03032
20130101; B60K 2015/0496 20130101; B60K 2015/03493 20130101; B60K
15/0406 20130101; B60K 15/03177 20130101; B60K 2015/0451
20130101 |
International
Class: |
B60K 15/04 20060101
B60K015/04; B60K 15/03 20060101 B60K015/03 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2011 |
DE |
10 2011 105 706.8 |
Claims
1.-13. (canceled)
14. A fuel tank closure system, comprising: a fuel tank to hold
hydrocarbon fuel, the fuel tank having a tank wall of
thermoplastics with a barrier layer for hydrocarbons, with at least
one orifice having a circumference; a closure cap fastenable to the
fuel tank to close the orifice; at least one first seal enclosed
between the closure cap and an outer surface of the tank wall when
the closure cap is fastened to the fuel tank; and at least one
second seal which is supported by the tank wall on the tank wall in
a region of the orifice when the orifice is open, the at least one
seal covers or shields a part of the tank wall exposed to
hydrocarbon fuel when placed in the fuel tank; and wherein the
orifice has an edge with a circumferential face defined by a
cross-sectional thickness of the tank wall, and the second seal
covers or shields the cross-sectional thickness of the tank wall
defining the circumferential face of the edge of the orifice from
exposure to the hydrocarbon fuel; wherein the second seal comprises
an elastomeric ring in the orifice; and wherein the elastomeric
ring comprises a sealing skirt which covers or shields the
circumferential face of the edge of the orifice.
15. The closure system according to claim 14, wherein the second
seal comprises a surface covering on the tank wall, which is
restricted to covering a surface of the tank wall in the region of
the orifice.
16. The closure system according to claim 15, wherein the surface
covering comprises a coating.
17. The closure system according to claim 16, wherein the coating
is a plasma coating.
18. The closure system according to claim 16, wherein the coating
is a finish coating.
19. The closure system according to claim 14, wherein the second
seal comprises a surface treatment of the tank wall, which is
restricted to treating the tank wall in the region of the
orifice.
20. The closure system according to claim 19, wherein the surface
treatment comprises at least one of fluorination and
sulphonation.
21. The closure system according to claim 14, wherein the closure
cap comprises a collar which protrudes into the orifice and the
collar comprises at least one circumferential sealing lip, which
covers the circumferential face of the edge of the orifice.
22. The closure system according to claim 21, wherein the sealing
lip is captively fastened to the closure cap.
23. The closure system according to claim 21, wherein the sealing
lip is injection moulded onto the closure cap.
24. The closure system according to claim 14, wherein the closure
system comprises a bayonet closure.
25. The closure system according to claim 14, wherein the closure
cap cooperates with a closure means of the fuel tank to close the
orifice.
26. The closure system according to claim 25 wherein the closure
means is provided at the circumference of the orifice and
configured such the closure cap is fastenable to the fuel tank.
27. The closure system according to claim 26 wherein the closure
means comprises at least one bayonet ring, which is moulded into
the tank wall.
28. The closure system according to claim 27, wherein the bayonet
ring comprises a plurality of retaining claws.
29. The closure system according to claim 14, wherein the second
seal is formed of rubber.
30. The closure system according to claim 29, wherein the rubber is
fluorine rubber.
Description
[0001] The invention relates to a closure system on a fuel tank of
thermoplastics with barrier properties for hydrocarbons, with at
least one orifice and with a closure cap which closes the orifice
in a sealing manner and which cooperates in a form-fitting manner
with closure means provided at the circumference of the orifice and
encloses at least one first sealing means between it and a tank
wall.
[0002] Such closure systems on plastics fuel tanks are sufficiently
well known. They are found for example in the region of fuel tank
service orifices and in the region of fuel delivery modules
inserted into the fuel tank. The caps closing the orifice are
generally provided with passages with fuel lines and/or electrical
leads. A metallic bayonet ring is conventionally moulded into the
plastics fuel tank on production thereof, in the region of the
orifice. Systems are also known which are provided with a flange
moulded onto the tank with a union joint or a union clamp closure.
The closure cap cooperates with closure means of the bayonet ring.
An elastomeric sealing ring is normally inserted between closure
cap and tank orifice.
[0003] Modern fuel tanks are made from HDPE-based thermoplastics,
the tank wall being formed of multilayer extrudates with
non-exposed barrier layers for hydrocarbons. A typical multilayer
structure of the wall of a fuel tank comprises, when viewed from
the inside to the outside, at least one inner layer of pure,
uncoloured HDPE, at least one layer of "regrind", i.e. of recycled
plastics, at least one coupling agent layer, at least one barrier
layer of EVOH, a further coupling agent layer and a layer of HDPE,
which is conventionally pigmented, i.e. coloured with carbon black.
The coupling agent layers consist of a modified LDPE. Such tank
walls have proven extremely resistant to hydrocarbons. The tank
walls are multilayer-extruded and shaped into the finished fuel
tank by extrusion blow moulding, thermoforming or the like. Modern
motor vehicle tanks and motor vehicles have to meet the "PZEV/LEV
II or LEV III" standard, this being a US standard for low-emissions
vehicles which sets specific hydrocarbon emission limit values for
motor vehicles and fuel tank systems.
[0004] In principle, any orifice in a fuel tank constitutes a
potential leakage path for hydrocarbons, since the tank wall
barrier system is interrupted in the region of orifices.
[0005] In the above-stated closure systems, although elastomeric
seals are used, which seal the system effectively relative to the
outside, as a result of design features hydrocarbon vapours or
liquid fuel reach the seal in the region of the tank closure and
thus reach a region of the tank body which lies outside the EVOH
barrier of the tank wall. In the region of the orifice of the
closure system, fuel is able to migrate around the EVOH barrier of
the tank wall. In particular, the circumferential face of the
orifice edge and regions of the orifice edge on the side of the
tank wall facing away from the tank, which are surrounded by the
seal, are exposed to the fuel. Hydrocarbons diffusing into the
material at this point creep under the seal and escape out of the
tank wall in a region beyond the seal. This does not happen in
appreciable quantities, but these quantities play a decisive role
in the course of overall system optimization.
[0006] Finally, the face of the circumferential orifice edge is
exposed at any rate to hydrocarbons, such that hydrocarbons may
enter the tank wall at the end/face.
[0007] The object of the invention is therefore that of improving a
closure system of the above-mentioned type in this respect.
[0008] The object underlying the invention is achieved by a closure
system on a fuel tank of thermoplastics with barrier properties for
hydrocarbons, with at least one orifice and with a closure cap
which closes the orifice in a sealing manner and which cooperates
in a form-fitting manner with closure means provided at the
circumference of the orifice and encloses at least one first
sealing means between it and a tank wall, the closure system
according to the invention being distinguished in that the tank
wall is provided in the region of the orifice with at least one
second sealing means, which covers at least a part of the tank wall
surfaces exposed to hydrocarbons.
[0009] The second sealing means is particularly preferably
constructed such that it covers the circumferential face of the
edge of the orifice.
[0010] The second sealing means may for example take the form of a
surface covering on the tank wall, which is restricted to the
surface in the region of the orifice. Alternatively, the second
sealing means may take the form of a surface modification of the
tank wall, which is restricted to the regions of the tank wall
adjoining the orifice.
[0011] Both a surface modification of the tank wall and a surface
covering on the tank wall in a locally strictly delimited region of
the tank wall is straightforwardly possible with little effort
during finishing after production of the tank body. Provision is
conveniently made for the tank wall to be modified or coated or
indeed otherwise covered in that region which, when viewed in the
circumferential direction of the orifice, is located inside the
conventionally provided elastomeric seal.
[0012] In a preferred variant of the closure system according to
the invention, provision is made for the surface covering to take
the form of a coating, in particular a plasma coating or a
finishing coat.
[0013] In the case of surface modification, it is sensible and
convenient to produce a chemically polar surface in the region of
the exposed area of the tank wall, in particular because
hydrocarbons are chemically non-polar systems.
[0014] In one advantageous variant of the closure system according
to the invention, provision is made for the tank wall to be treated
by fluorination or sulphonation, this surface treatment being
restricted to the regions of the tank wall adjoining the orifice
and the tank wall additionally comprising at least one or more
non-exposed barrier layers for hydrocarbons.
[0015] The closure system according to the invention may be
distinguished, for example, in that the second sealing means takes
the form of an elastomeric ring, preferably with a sealing skirt
centred in the tank orifice. The sealing skirt may for example rest
against the internally circumferential face of the tank edge. The
elastomeric ring may comprise overall in cross section an angular
profile with a flat, flange-like edge, which rests externally on
the tank wall and preferably only covers that region of the tank
wall which is located inside the regular elastomeric seal.
[0016] The sealing skirt conveniently covers the circumferential
face of the edge of the orifice completely.
[0017] Alternatively or in addition, provision may be made for the
closure cap to comprise a collar protruding into the tank orifice
and for the collar to comprise at least one circumferential
elastomeric sealing lip, which covers the circumferential face of
the edge of the orifice. Provision may furthermore be made for the
closure cap to be provided with a moulded-on elastomer at the
bottom of a cap flange and in the region of a circumferential
collar protruding into the orifice.
[0018] If the collar comprises elastomeric sealing lips, said
sealing lips may be captively fastened to the closure cap.
[0019] According to the invention, one or more sealing lips may be
provided, which extend for example at a distance from one another
over the circumference of the collar. One or more sealing lips may
for example also form a labyrinth-like sealing system.
[0020] One or more elastomeric sealing lips may for example be
injection-moulded onto the closure cap. The closure cap may consist
for example of polyamide, POM or ABS. Fluorine rubber materials,
for example, are suitable for the elastomeric sealing lips.
[0021] The above-mentioned elastomeric ring and the sealing skirt
provided thereon may also consist of a fluorine rubber
material.
[0022] The closure system conveniently takes the form of a bayonet
closure. It goes without saying that the closure system may also be
constructed as a union joint or otherwise.
[0023] At least one bayonet ring with retaining claws, which ring
is moulded into the tank wall, may be provided as the closure
means. If the fuel tank is extrusion blow moulded, the bayonet ring
is preferably blow moulded into the tank wall.
[0024] The invention will be explained below with reference to an
exemplary embodiment shown in the drawings, in which:
[0025] FIG. 1 shows a plan view of the fuel tank according to the
invention in the region of a service orifice,
[0026] FIG. 2 shows a cross section through the closure system
according to a first variant of the invention and
[0027] FIG. 3 shows a cross section through the closure system
according to a second variant of the invention.
[0028] The closure system 1 according to the invention is provided
on a fuel tank 2 of thermoplastics, which was obtained by extrusion
blow moulding or by thermoforming or by welding together
injection-moulded half-shells from multilayer plastics extrudates.
The tank wall 3 of the fuel tank 2 has an at least six-layered wall
structure comprising an inner HDPE layer, a recycled layer, a
coupling agent layer, an EVOH barrier layer, a further coupling
agent layer and an outer HDPE layer. The inner HDPE layer consists
of "virgin" HDPE, the coupling agent layers of LDPE, the barrier
layer for example of EVOH and the outer layer forming the outside
of the tank of HDPE coloured with carbon black.
[0029] In the drawings, the multilayer structure of the tank wall 3
is shown only in a highly schematically simplified manner.
[0030] The closure system 1 comprises an orifice 4 and a closure
cap 5 inserted into the orifice 4. The orifice 4 takes the form of
a circle cut out of the tank wall 3 and is surrounded by a metallic
bayonet ring 6 with retaining claws 7. The bayonet ring 6 comprises
a flanged ring 8 moulded into the tank wall 3, which flanged ring
comprises a plurality of holes 9 around its circumference, through
which passes the thermoplastic material of the tank wall 3.
[0031] The bayonet ring 6 was blow moulded into the tank wall 3 by
extrusion blow moulding during production of the fuel tank 2. It
was inserted into the die during production and flowed through by
the material of the parison on expansion of the parison in the die.
A circle was subsequently cut out to form the orifice 4 after
removal of the fuel tank from the die.
[0032] As is clear in particular if FIGS. 1 and 3 are looked at
together, the bayonet ring 6 comprises a plurality of
cross-sectionally angular retaining claws 7 arranged spacedly from
one another and surrounding the closure cap 5. The closure cap 5
comprises a circumferential collar 10, the diameter of which
corresponds approximately to the diameter of the orifice 4 and
which is centred in the orifice 4 when inserted. When the closure
cap 5 is inserted into the orifice 4, the circumferential edge 11
of the closure cap 5 rests against an elastomeric seal 12, which
takes the form of an O-ring seal. The elastomeric seal 12 in this
case rests on the tank wall 3 inside the region delimited by the
retaining claws 7.
[0033] The barrier layer 13 for hydrocarbons, extending in the tank
wall 3, is merely indicated in the drawing as a line. As is
straightforwardly apparent from FIGS. 2 and 3, on the
outward-facing side of the tank wall 3 the elastomeric seal 12
encloses a region of the tank wall 3 which is exposed when the
closure cap 5 is inserted to hydrocarbons in the liquid or in the
gas phase. The internally circumferential face 14 of the edge of
the orifice 4 is likewise normally exposed. In this region, the
barrier layer 13 is freely accessible or cut away.
[0034] In the variant of the closure system 1 according to the
invention, which is shown in FIG. 2, the collar 10 of the closure
cap 5 is provided on its side facing the face 14 with moulded-on
elastomeric sealing lips 15, which, in the position in which the
collar 10 is centred within the orifice 4, rest against the face 14
in such a way as to reliably prevent the penetration of
hydrocarbon, whether in the gas phase or in the liquid phase, into
the orifice such that the region of the tank wall 3 above the
barrier layer 13 comes into contact with hydrocarbons.
[0035] A further variant of the closure system 1 according to the
invention is shown in FIG. 3, the closure cap 5 not being shown for
reasons of simplification. In addition to the elastomeric seal 13,
a further sealing ring 16 is inserted into the orifice 4. This
sealing ring has a profile which is cross-sectionally, for
instance, angular and a skirt 17 projecting into the orifice 4, the
length of which is somewhat greater than the wall thickness of the
tank wall 3, such that the skirt 17 completely covers the face 14
of the orifice 4. When the closure cap 5 is inserted, the skirt 17
comes to lie between the collar 10 of the closure cap 5 and the
face 14 of the orifice 4. As an alternative to the illustrated
variants of the closure system 1 according to the invention,
provision may be made for the entire surface of the tank wall 3 to
be coated or surface-modified inside the region defined by the
retaining claws 7, including the surface of the face 14 of the
orifice 4.
LIST OF REFERENCE NUMERALS
[0036] 1 Closure system [0037] 2 Fuel tank [0038] 3 Tank wall
[0039] 4 Orifice [0040] 5 Closure cap [0041] 6 Bayonet ring [0042]
7 Retaining claws [0043] 8 Flanged ring [0044] 9 Holes [0045] 10
Collar [0046] 11 Edge [0047] 12 Elastomeric seal [0048] 13 Barrier
layer [0049] 14 Face [0050] 15 Sealing lips [0051] 16 Sealing ring
[0052] 17 Skirt
* * * * *