Note: Descriptions are shown in the official language in which they were submitted.
' CA 02381575 2002-02-14
Coolant pipe for an internal combustion engine and a process for the
production of such a pipe
Coolant pipes or hoses, on motor vehicle engines, have hitherto
frequently been in the form of metal pipes or metal hoses which are
respectively provided at their ends with coupling elements for quick-action
coupling purposes, in the form of a detent or snap-action coupling. The
coupling elements are in the form of metal sleeves, for example comprising
aluminum sheet, and are pressed or clamped on to the respective end of
the hose or pipe. They comprise for example an outer sleeve and an inner
sleeve of sheet metal, wherein the hose or pipe is fitted into the annular
space between the outer sleeve and the inner sleeve. Fixing on the hose or
pipe is effected by cold deformation of the outer sleeve, for example by
folding over a crimping edge. The outer sleeve is peripherally provided with
retaining or detent projections co-operable with corresponding retaining or
detent openings and retaining or detent springs of a counterpart coupling
portion, for example on a motor vehicle radiator unit. The inner sleeve
forms an annular flange for bearing against a corresponding counterpart
surface in the counterpart coupling portion. A peripherally extending groove
2o serving as a sealing seat for an O-ring seal is formed between the annular
flange of the inner sleeve and the outer sleeve.
Coupling portions of that kind are. comparatively expensive to
produce and in particular the procedure involved in mounting the coupling
portions on the hoses or pipes, that is to say producing a connection
z5 between the coupling portions and the hoses or pipes which affords
adequate sealing integrity and which is non-releasable, is complicated and
expensive.
DE 195 43 318 A1 describes by way of example the connection
between a fluid conduit of plastic material and a tubular coupling element
3o also of plastic material, with the coupling element being injection-molded
to
the conduit. For that purpose, the end portion of the conduit or pipe when
already in a finished condition is put on to a cylindrical part of a molding
1
CA 02381575 2002-02-14
s
10
20
30
(continued from page 1 line 32 of the translation of the original PCT text)
a molding
1 AMENDED PAGE
CA 02381575 2002-02-14
r
tool core and then, in a separate working operation, the coupling element is
injection-molded around the part of the molding tool core, which is
disposed outside the pipe.
The production of such a pipe assembly are extremely complicated
and expensive.
WO 89/04755 discloses a pipe as set forth in the classifying portion
of claim 1, which was produced by extrusion suction blow molding. The pipe
described therein is provided at one or both ends with coupling elements
which were formed in one piece on the pipe during production thereof.
In regard to a large number of conceivable uses for such a pipe, for
example as a coolant pipe on motor vehicle engines, it is desirable to
provide at the connections of the pipe or hose, sealing means for different
temperature ranges in respect of the medium flowing through the pipe.
The present invention is therefore based on the problem of improving
a pipe or hose as set forth in the classifying portion of claim 1 in terms of
the possibility of using it when major fluctuations in temperature are
involved.
That problem is solved by the features of claim 1.
The pipe in accordance with the present invention can obviously also
be used in other ways, for example in cooling units or in other drive
concepts.
Such a pipe which is produced integrally with coupling elements at
one or both ends thereof eliminates the need for the separate production of
coupling elements and the operation for securing same to the pipe in
sealing and non-losable relationship, thereby affording a considerable
saving in terms of manufacturing time and cost. Particularly when the pipe
is produced in accordance with the invention by extrusion blow molding and
the detent means of the detent coupling are provided in the external
contour of the respective end of the pipe, manufacture of the pipe with at
least one part of the detent coupling can be implemented in a single tool.
Finally, producing the pipe from thermoplastic material affords advantages
in consideration of the saving in weight and material that this entails.
Plastic
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CA 02381575 2002-02-14
material is a comparatively light and inexpensive material whose elasticity
and toughness as well as its resistance to acid and temperature can be
easily adjusted by virtue of choosing the appropriate composition of
material. There is also the possibility of producing pipes or hoses which
have different moduli of elasticity or degrees of stiffness over their length,
whereby it is possible to produce parts whose handleability is optimised in
terms of final assembly for example in a motor vehicle.
It will be apparent to the man skilled in the art that the terms pipe
and hose at any event denote a tubular element for which depending on the
1o respective diameter and stiffness one term or the other is preferably used,
so that hereinafter only the term pipe will be employed.
In accordance with the preferred embodiment of the invention the
pipe is produced by suction blow molding, in particular by extrusion suction
blow molding. That process has proven to be particularly advantageous for
the production of pipes which are not of a rotationally symmetrical
configuration, that is to say for example which have a curved configuration
in space, in respect of their longitudinal axis. Producing the pipe by a
suction blow molding process also affords the advantage that it does not
involve any welded seam.
The pipe is provided with at least one insert pipe connection as a
separate component which has a flange for bearing against a counterpart
surface in a counterpart coupling portion or on a connection component.
The insert connection portion is advantageously non-losably inserted into
the respective end of the pipe. A particularly advantageous feature provides
that the insert connection portion is non-releasably latched to the
respective end of the pipe. For that purpose, it may be provided at its
external periphery with retaining or detent projections co-operable with a
peripherally extending bead or ridge as a detent or retaining recess or a
peripherally extending step in the internal wall of the pipe.
The insert connection portion can be produced for example from
thermoplastic material in one working operation by blow molding or suction
blow molding with the pipe, but in that case, when using such a production
3 AMENDED PAGE
CA 02381575 2002-02-14
process, forming the flange for bearing against a counterpart surface on a
counterpart coupling portion or a connection component is found to be
difficult. It is therefore particularly advantageous for the insert connection
portion to be produced by injection molding of thermoplastic material. This
can involve the same composition of material as the pipe.
In the preferred embodiment of the pipe the respective end forming
the detent coupling is expanded, and the insert connection portion is sealed
in relation to the internal wall of the pipe, preferably in the region of the
regular cross-section of the pipe.
1o The respective end of the pipe forming the detent coupling can have
an inwardly disposed collar which with the flange of the insert connection
portion forms a peripherally extending sealing seat, for accommodating an
O-ring seal.
The end of the insert connection portion which is remote from the
flange may also have a peripherally extending groove for accommodating
an O-ring, which bears sealingly against the inside wall of the pipe
substantially in the region of the regular diameter of the pipe.
A two-part coupling element which is formed in that way and of
which the part of the detent coupling, which is formed integrally with the
2o pipe, forms the actual part that co-operates with the counterpart coupling
portion, affords the possibility of involving various sealing means for
different temperature ranges in respect of the medium which flows through
the pipe. For example, the seal between the insert connection portion and
the pipe may be in the form of a seal for a low-temperature range whereas
the seal between the flange of the insert connection portion and the end of
the pipe can be designed in the form of a high-temperature seal. The
reverse configuration is also possible, according to the circumstances of
installation involved.
Preferably the pipe according to the invention comprises polyamide,
3o a particularly preferred embodiment comprising glass fiber-reinforced
polyamide.
4 AMENDED PAGE
CA 02381575 2002-02-14
The process according to the invention for the production of a pipe or
hose of thermoplastic material by extrusion suction blow molding, in
particular as a coolant pipe for internal combustion engines, wherein at
least at one end of the pipe at least one part of a detent coupling or snap-
s action coupling is formed on the pipe in one piece therewith in one working
operation, wherein detent means of the detent coupling are formed in the
outside contour of the respective pipe end, is distinguished by the
production of at least one insert connection portion of thermoplastic
material as a separate component, wherein the insert connection portion is
1o provided with a flange for sealingly bearing against a counterpart surface
of
a counterpart coupling portion or a connection component, and by the non-
losable connection of the insert connection portion to an end of the pipe.
It is not necessary from a technical point of view for the insert
connection portion to be non-losably or non-detachably connected to the
15 pipe, in regard to the effectiveness of the coupling formed on the pipe,
but
such a non-detachable connection affords advantages in terms of delivery,
stockkeeping and preparation of the pipes for assembly.
As an alternative to production of the insert connection portion as a
separate component, it can be provided that an insert connection portion is
2o produced together with the pipe in one working operation by suction blow
molding, and the insert connection portion is separated from the pipe in a
further working operation in order to be non-losably inserted into an end of
the pipe.
The invention is described hereinafter by means of an embodiment
25 illustrated in the drawings in which:
(continue on page 5, line 26 of the translation of the original PCT text)
AMENDED PAGE
' CA 02381575 2002-02-14
Figure 5 is a perspective view of a counterpart coupling portion
provided on a connection component, and
Figures 6 to 9 are diagrammatic views showing various steps in the
process of extrusion suction blow molding for a pipe according to the
invention.
Figures 1 and 2 show the pipe 1 in accordance with the invention, in
the form of a coolant pipe for an internal combustion engine. The pipe 1
was produced by extrusion suction blow molding and comprises glass fiber-
reinforced polyamide. Formed at each end of the pipe 1 is a detest coupling
2 which was produced in one working operation during the procedure for
molding of the pipe 1. The detest couplings 2 are of a complementary
configuration to a counterpart coupling portion 3 which is illustrated in
Figure S and into which the detest couplings 2 can be engaged in sealing
relationship by a latching action.
The longitudinal axis of the pipe 1 is of a configuration which is
curved in space and the pipe 1 is overall of an asymmetrical nature. The
ends of the pipe 1 are somewhat conically enlarged in the region of the
detest couplings 2. Adjoining the enlargement portions 4 is a cylindrical
portion 5, over the outside periphery of which are distributedly arranged a
2o plurality of detest projections 6. The detest projections 6 are of a semi-
trapezoidal cross-sectional contour and, in the direction of the mouth
opening 7 of the pipe, form a respective inclined run-on surface 8.
In the region of the mouth opening 7 the pipe 1 is provided with an
inwardly disposed collar 9; the diameter step between the cylindrical
portion 5 and the collar 9 forms a peripherally extending step or shoulder
10 in the internal wall of the pipe 1, by virtue of the pipe 1 being produced
in the form of a blow-molded component. Further reference will be made
hereinafter to the step or shoulder 10.
The external contour of the detest coupling 2, which was obtained by
extrusion suction blow molding, approximately corresponds to the external
contour of the known multi-part coupling elements made from sheet metal,
which co-operate with the counterpart coupling portion which is indicated in
6
' CA 02381575 2002-02-14
Figure 5 but which is not subject-matter of the present invention. The
detent coupling 2 is fitted into the counterpart coupling portion 3 in such a
way that the detent projections 6 are fitted into groove passages 11 which
extend in the counterpart coupling portion 3, in the direction of insertion of
the detent coupling 2. Disposed transversely with respect to the insertion
direction, in the groove passages 11, are detent spring slots 12. Detent
springs 13 pass through the slots 12. The detent springs 13 are urged
radially outwardly by way of the inclined run-on surfaces 8 of the detent
projections 6, and spring back into their initial position behind the detent
projections 6, whereby the detent coupling 2 of the pipe 1 is latched non-
detachably to the counterpart coupling portion 3.
The pipe 1 illustrated by way of example herein has a total of two
detent projections 6. It will be apparent to the man skilled in the art that
the detent coupling may comprise more than two detent projections or
even a peripherally extending detent protrusion.
In order to achieve adequate sealing integrity for the detent coupling
2 in the counterpart coupling portion 3, the assembly includes an insert
connection portion which is identified by reference 14 and which was
produced from polyamide by an injection molding process. The insert
connection portion 14 is substantially in the form of a hollow-cylindrical
plug-in element which is provided at one end with an annular flange 15. As
can be seen from Figure 4 the insert connection portion 14 forms a part of
the coupling on the pipe 1 and is inserted into the pipe 1 in such a way that
the annular flange 15 forms the end face of the mouth opening 7. The
annular flange 15 is comparatively thin-walled so that it is flexible within
certain limits upon being inserted into the counterpart coupling portion 3.
In the region of its insertion end 16 the insert connection portion 14
is provided with a peripherally extending annular groove 17 which
accommodates an O-ring seal 26. In the region of the annular flange 15 of
3o the insert connection portion 14, which forms a collar, provided on the
outside periphery of the cylindrical tubular body part of the insert
connection portion 14 there are also detent projections I8 which are co-
7
CA 02381575 2002-02-14
operable with the peripherally extending shoulder 10 in the inside wall of
the pipe 1. The detent projections 18 also form inclined run-on surfaces
which are inclined in the direction of the insertion end 16 of the insert
connection portion 14. The detent projections 18 and the shoulder 10 are of
such a configuration or co-operate in such a way that the insert connection
portion 14 can be non-losably fitted into the respective end of the pipe by a
snapping engagement or a detent retaining engagement. The insert
connection portion 14 can be released or pulled out of the pipe 1 again only
by applying substantial forces. It will be apparent to the man skilled in the
art that there is no need for the insert connection portion 14 to be secured
in position when the detent coupling 2 is inserted into the counterpart
coupling portion 3.
When the insert connection portion 14 is in the condition of being
snap-fitted into the pipe 1 the annular flange 15 together with the inwardly
disposed collar 9 of the pipe 1 forms a peripherally extending sealing seat
for accommodating a further O-ring seal 27. The O-ring seal 27 provides for
sealing integrity as between the pipe 1 and the counterpart coupling portion
3. When the detent coupling 2 and the counterpart coupling portion 3 are
fitted one intowthe other, the annular flange 15 bears against a counterpart
2o surface or sealing surface provided by the counterpart coupling portion 3.
The O-ring seal 27 which is provided in the region of the insertion
end 16 of the insert connection portion 14 bears against the inside wall of
the pipe 1 approximately in the region of its regular diameter and thereby
seals off the insert connection portion 14 in relation to the pipe 1.
The process for production of the pipe according to the invention is
diagrammatically shown in Figures 6 to 9.
Reference numeral 19 therein denotes an extrusion head and which
is provided with a blowing bar or tube 20. The extrusion head 19 extrudes a
tubular portion of softened thermoplastic material into a closed two-part
tool 21, whose mold cavity 22 corresponds to the contour of the finished
pipe to be molded. As shown in particular in Figure 6 a suction device 23 at
the lower end of the mold cavity 22 promotes the movement of the
8
CA 02381575 2002-02-14
extruded tubular portion through the cavity 22, the tubular portion 24 or
extrudate being acted upon with pre-blowing air from the blowing tube 20.
After the tubular portion 24 has filled with the cavity 22 over the
preselected length, the ejection of material from the extrusion head 19 is
terminated. The tubular portion 24 is clamped off at the upper and lower
ends of the tool 21, by means of slider members 25 which close off. Both
the suction air and the blowing air are shut off. The slider members 25 and
the tool 21 are then opened so that the finished article can be removed
from the mold.
The advantages of the process described hereinbefore in regard to
the pipe according to the invention, will be readily apparent. The pipe can
be produced without any seam. Controlling the reduced pressure generated
by the suction device 23 means that the extrudate can be drawn over the
desired length even into molds entailing a spatially complex structure. A
closing force for the tool is required only for holding it closed in
opposition
to the blowing pressure.
It will be appreciated that the pipe according to the invention can
also be produced in the form of a conventional blow-molded article.
9
' CA 02381575 2002-02-14
Coolant pipe for an internal combustion engine and a process for the
production of such a pipe
List of references
1 pipe
2 detent coupling
3 counterpart coupling
portion
4 enlargement
cylindrical portion
6 detent projections
7 pipe mouth opening
8 inclined run-on surface
9 collar
step
11 groove passage
12 detent spring slots
'
13 detent springs
14 insert connection portion
annular flange
16 insertion end
17 annular groove
18 detent projections
19 extrusion head
blowing bar
21 tool
22 cavity
23 suction device
24 tubular portion
slider member
26 O-rings
27 O-rings
