Note: Descriptions are shown in the official language in which they were submitted.
2103686
Drainage Pipe
Thiq invention pertains to a plastic drainage pipe in
accordance with the preamble to Claim 1.
Drainage pipes are mainly used in road construction
and are laid along the side of the road in place of the
customary ditche~ previously used. As a rule, such drain-
age pipes are manufactured from plastic in finite lengths
of 6 m for example.
In a known embodiment, the cross-section of the drain-
age pipe is tunnel-shaped. The inner wall surface is
smooth, as is most of the outer wall surface. Merely the
upper part of the outer wall surface has furrows running
parallel to the pipe axis in the area of which the pipe
wall ha~ croqs slit3 in order to take in external water.
Such a drainage pipe has the advantage of a high drainage
volume as a result of the smooth inner surface. This pipe
is relatively heavy, however, because it has to have rela-
tively large wall thicknesses in order to achieve a cer-
tain rigidity, so that deflection i3 reduced during trans-
port and adequate rigidity is achieved in the loaded state.
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These strength problems are solved by means of another
known design of the cross-section of the drainage pipe
: with the pipe having transverse waves over its entire
length in whose wave troughs slit-like openings are cut in
perpendicularly to the pipe axis. These transverse waves
. give the drainage pipe greater rigidity with reduced wall
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210~686
thickne~, but at the expen~e of the drainage volume,
which reaches, based on the same diameter, only about two-
third~3 of the drainage volume of the smooth pipes on
account of the transver~e waves.
The tunnel ~hape of such drainage pipes ha~ the advan-
tage of being easy to lay, because the level base of the
pipe provides the correct installation position. On the
other hand, however, tunnel-shaped drainage pipes can be
manufactured only with a high tool outlay and result in
problems in regard to the seal at the connecting area
between two adjacent pipes.
Finally, double-walled pla~tic pipeR are known in
which the inner pipe is smooth-walled and the outer pipe
ha~ transverse waves. Both pipeY are connected to one
another in the area of the wave troughs.
Such a double-walled drainage pipe is known from DE-OS
36 05 329 and can be u~ed a~ a multi-purpose, full, or
partial drainage pipe consisting of a smooth inner pipe
and a corrugated outer pipe, the corrugated pipe having
two hollow strips running the length of the corrugated
pipe which fill the wave trough~ and which are arranged in
relation to one another in an angle of a = 120 related ~o
the pipe axis and the slit-like openings are located only
in the area enclosed by the angle a. These strips prevent
the drainage liquid draining of f along the wave
troughs and the location of the strip~ provides a good
orientation aid for correct laying of the drainage pipe.
The webs cannot be broadened as de~ired with this two-wall
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3 21036~6
pipe, because otherwise the crushing strength would be too
small .
It is the objective of this invention, therefore, to
design a drainage pipe in such a way that it can be used
a~ a multi-purpose or partial drainage pipe with markedly
improved rigidity,which is less expensive to manufacture
and provides better drainage.
This objective is solved through the invention ~pec-
ified in Claim 1, preferred embodiment3 of the invention
being described in the sub-claims.
The pipe ~ystem is provided with much greater rigidity
by the addition of a third pipe forming an outer pipe.
Damage to the inner pipe resulting from it being laid in
hard or lumpy materials like gravel is avoided. The con-
nection to the surrounding filling material is improved.
The arrangement of the slit-like openings and their
corresponding indentations in the outer pipe are al30 an
orientation aid for the laying of round pipes. Round pipe~
are especially stable, withstand a high crushing force,
can be laid easily, and can be connected easily with one
another.
If no slit-like opening~ at all are provided, then the
inventive three-wall drainage pipe can be used a~ a highly
stable, impermeable sewer pipe.
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4 2103686
Moreover, in accordance with the invention the funnel-
shaped impres~ion~ in the outer pipe are de~igned in ~uch
a way that ~hey protect the water intake openings from
becoming dirty and provide hydraulic advantage~ for carry-
ing water.
In a preferred embodiment of the invention, there i8 a
shaped, expanded, or ~prayed-on, or welded-on ~leeve at
one end. A ~ealing ring can be inserted in a groove so
that the drainage pipes are easily connected together
axially with one another.
The invention is explained below in more detail u~ing
an embodiment. The drawings show as follows:
Fig. 1 a top view of a drainage pipe,
Fig. 2 a top view of a section of the drainage pipe,
Fig. 3 a cro~s-section through a circular drainage
pipe,
Fig. 4 a vertical longitudinal section through a
drainage pipe,
Fig. 5 a-c various alternatives for openings,
Fig. 6 a longitudinal cross-section in the area of
the connection of two drainage pipes,
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2103686
i~. 7 a longitudinal cross-section in the area of the
connection of two pipes, one pipe having a
welded-on sleeve.
The drainage pipe 1 illustrated in Fig. 1 consists of a
three-wall pipe whose outer pipe is essentially smooth. In
the upper area illustrated, the outer pipe 6 has indentations
9 which are shaped as groove-like depressions over an angle
range of approximately 110-220, and preferably 120, in the
circumferential direction. There are-openings 8 in the
depressions which create a connection between the area
surrounding the pipe and the interior of the pipe. There is
a shaped, expanded sleeve 10 on one end into which the non-
expanded end of another corresponding pipe section can be
inserted. Preferably, there are no depressions in the outer
pipe in the area of the sleeve.
The area of the non-expanded end of the pipe also has no
depressions but merely a circular groove 11 in which an O-
ring or a lip seal can be inserted so that when the non-
expanded end is inserted into another pipe a tight connection
is achieved. However, the groove is preferably formed in the
sleeve at the other end of the pipe.
Figure 2 shows an enlarged partial view from Fig. 1 from
which the funnel shape of the indentations 9 can be seen. The
indentations follow the wave troughs of the middle pipe. Each
indentation 9 contains three slits 8, which can be sunk, cut
in, stamped in, or sawn in the traditional manner. More than
3 slits may also be used.
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6 ~103686
The funnel ~hape of the depressions in the outer pipe
protects the water intake openings from becoming dirty and
provides hydraulic advantages for the carrying of water.
Figure 3 shows a cross-section through a pipe in
accordance with the invention. The inner pipe 2 i3 smooth
in the longitudinal direction and ~urrounded by a corru-
gated pipe 3 whose wave troughs 4 are each welded to the
inner pipe 2. The wave peaks are connected, in particular
welded, to another pipe surrounding the corrugated pipe 3 and
which is essentially smooth in the longitudinal direction.
Figure 3 shows a sectional plane in which one wave trough
of the corrugated pipe 3 is connected to the inner pipe 2.
In the upper area of the pipe, relative to the installa-
tion po~ition, the outer pipe 6 is indented towards the
inside and welded to one wave trough of the corrugated
pipe in this area. Consequently, a threefold wall thick-
ness at the sites of the indentations results. The open-
ings 8 are located in this area.
The slits can be made in the drainage pipe either by
means of sawing, stamping, or rotary cutting. Drill holes
can also ~be provided, in which case it must be ensured,
however, that in accordance with DIN 4262 at least 50 cm2
slit surface per metre remains.
The indentations in the outer pipe are preferably
longitudinal depressions, however several depressions
210368~
located be~ide one another can be provided. It i~ especial-
ly where the openings are drill holes that i~ can be pro-
vided that the indentation~ in the outer pipe are point-
shaped .
Figure 4 show~ a vertical section of an inventivepipe. It can be clearly seen that the outer pipe 6 i~
pressed into the wave troughs of the middle pipe 3 on the
upper side of the pipe and is perforated at the ~ite~ 8.
Figures 5 a - c show various type~ of openings in the
drainage pipe. Figure 5 a show~ an enlarged view of a
~imple ~lit. Figure 5 b ~how~ two parallel slits located
in one wave trough in order to reduce the size of the
individual ~lit. Finally, Figure 5 c ~how~ two parallel
qlits between which the outer pipe al~o ha~ an elevation
15. The slit~ can be off~et to one another in the circum-
ferential direction in all embodiments of Figure 5 in
order to improve further the overall strength of the pipe.
Preferably, corre~ponding indentation~ of the outer
pipe are found in every groove of the corrugated pipe. If
the slit~ are large enough and there are enough of them,
it can a~o be provided, for example, that only every
second wave trough be connected with an indentation in the
outer pipe.
Figure 6 showQ the connection between two drainage
pipe sections. In this Figure the sleeve end of one drain-
age pipe i~ expanded in ~uch a way that the non-expanded end of
a drainage pipe can be inserted into the sleeve without
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~103686
problems. It can be ~een once again in thi~ ca~e that the
~mooth-walled inner pipe is surrounded by a corrugated
pipe which is welded to the inner pipe in the area of the
wave troughs. The outer pipe 6 is smooth and i~ connected
to the outer crown ~uxfaces of the corrugated pipe 3. The
interior diameter of the sleeve end of the drainage pipe
i8 slightly larger than the diameter of the non-expanded end.
Preferably, a sealing ring, for example an O-ring or a lip
seal, can be inserted into a circular groove in the
non-expanded end or into a crease 20 in the sleeve end, the
groove being produced by pressing the outer pipe 6 over
its entire circumference into a wave trough of the corru-
gated pipe or being formed from a crea~e-shaped recess 20
of the inner pipe in the sleeve end (as illu~trated).
Figure 7 shows the design of a pipe with a welded-on
sleeve, as is preferred with large diameters in particular
because an expan~ion would mean a considerable expenditure
of time and money in thi~ ca~e. The sleeve 16 i5 shoved a
distance over the blunt cut-off end of a pipe and welded
or ~prayed on. The sleeve is one-walled and ha~ an
interior diameter which is ~lightly larger than the exter-
nal diameter of the drainage pipe.
There is a ring-shaped closure 17, which guarantees
that the leeve can be shoved onto the drainage pipe for a
defined length.
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2103686
On the front end of the sleeve there i~ a circular
crease 18 into which a sealing ring 19, in particular a
lip seal, can be inserted. This type of ~leeve connection
has the particular advantage that the drainage pipe can be
manufactured in indefinite lengths without the end~ being
given any special de~ign.
Due to the smooth outer pipe, it can be laid flu3h in
concrete or cohesive gravel, guaranteeing a good connec-
tion to the pipe so that water coming into contact with
the drainage pipe cannot flow off laterally from it but
almost all of it enters the openings 8 on the upper side
of the drainage pipe.
The inventive pipes can be made fr,om polyethylene,
polypropylene (which has a higher E-modulus ) and in speci-
fic cases also from PVC. In order to manufacture an inven-
tive drainage pipe, a double-walled pipe manufactured in
accordance with the state of the art i~ surrounded with a
third pipe by means of a further angular extruder head.
Immediately after exiting from the nozzle, the third pipe
i9 indented either by means of mould stamps or mould par~s
which move along with it. After being cooled in a water
bath and~cleaned, the slits can be added to the pipe, it
can be cut into lengths, and the sleeve formed in the
known manner.
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2103686
Reference Number List
1 Drainage pipe
2 smooth-walled inner pipe
3 corrugated pipe
4 wave trough
transverse waves
6 outer pipe
7 pipe axis
8 slit-like openings
9 indentation
expanded cleeve
11 circular groove
13 bevelling
14 seal
elevation
16 31eeve
17 closure
18 crease
19 sealing ring
crease
....
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