Pipe coupling

A pipe coupling, which renders it possible to connect branch pipes (24) to a feed-pipe (1) without requiring the flow in the feed-pipe to be shut off. In a cylindrical guide passageway (5) of one of two coupling parts (2a,2b) embracing the feed-pipe a piston (4) is located, which is provided with a passageway (10) for fluid connection between the feed-pipe and the branch pipe. The piston is provided with an internal knife (9) which upon rotation of the piston cuts up material out of the feed pipe to form the opening to the passageway and projects the cut-up material into the guide passageway (5) to assist in anchoring the coupling in place.

BACKGROUND OF THE INVENTION 
This invention relates to a pipe coupling for connecting branch pipes to a 
feed-pipe without requiring flow interruption in the feed-pipe. 
PRIOR ART 
Pipe couplings of this type are known in a great number of different 
embodiments, as described, for example, in British Pat. No. 1,034,138, 
French Patent No. 122 557 and U.S. Pat. No. 3,983,897, where, for 
connection between the feed-pipe, and the branch pipe a passageway is 
formed in the pipe coupling. The present invention comprises more 
precisely, as known previously, coupling parts, which sealingly embrace 
the feed-pipe, a cylindrical guide passageway extending through one 
coupling part, a fluid-tight piston in the guide passageway, which piston 
at its inner end is provided with a knife-shaped cutting-up member and is 
formed with a passageway for fluid connection between the feed-pipe and 
the branch pipe which is connected to the coupling part, in such a manner, 
that in assembled position of the coupling parts a portion of the 
feed-pipe projects in a radial direction into and intersects the guide 
passageway. 
In the pipe coupling of U.S. Pat. No. 3,983,897, the said projecting 
portion of the pipe shell is cut off by translation of a valve body in a 
guide passageway. The said movement is effected, for example, by a 
detonation cartridge which is detonated by a hammer stroke on a firing 
pin. This pipe coupling thereby not only has the disadvantage of being 
complicated, but it also involves a certain risk in connection with the 
handling of detonation cartridges. The known construction, further, 
implies certain sealing problems. 
SUMMARY OF THE INVENTION 
With a pipe coupling according to the present invention it is possible by a 
simple structural design to provide the feed-pipe in a simple and 
efficient way with one or more holes for fluid connection to the 
passageway in the coupling part. The flow area of the holes can be made at 
least as great as the feed-pipe area. It is further possible that the 
portion, which was cut-up from the feed-pipe when making of the hole is 
retained attached to the feed-pipe and is folded up in the guide 
passageway of the coupling part, so that said cut-up portion contributes 
to an efficient locking between the pipe coupling and the feed-pipe. The 
pipe coupling according to the invention has the further essential 
advantage, that complete sealing between the feed-pipe and the branch pipe 
is obtained when the piston is in the position in which the connection 
between said pipes is to be shut off. 
The characterizing features of the invention for achieving the aforesaid 
advantages become apparent from the attached claims.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
As appears from the embodiment shown in FIGS. 1-4, the pipe coupling 
comprises coupling parts 2a and 2b, which are sealed about a feed-pipe 1 
and by means of, for example, screws 3 are interconnected and embrace said 
feed-pipe. The coupling further comprises a piston 4 inserted in one 
coupling part. The seal between the coupling part 2b and the feed-pipe 1, 
and also between contacting surfaces of the coupling parts 2a and 2b 
preferably can be effected by means of a sealing paste. 
The coupling part 2b is formed with a guide passageway or cylinder 5, which 
in assembled position of the coupling parts is directed perpendicularly to 
the feed-pipe 1. In said position a portion of the feed-pipe projects into 
the guide passageway. The coupling part 2b further is provided with a 
connection 6 for a branch pipe (indicated by dashed lines 24 in FIG. 1), 
which connection projects out of the coupling part 2b perpendicularly 
relative to the guide passageway. The passageway 5 has at its inner end 
closest to the feed-pipe 1 a widened portion 7, and at its outer end 
portion beyond the connection 6 it is formed with a recess 8. 
The outer diameter of the piston 4, which in FIG. 2 is shown separated from 
the coupling part 2b, and in FIG. 4 is shown in place in the coupling part 
2b in an operative position for the pipe coupling, is adapted to the 
cylindrical shape of the guide passageway 5. The inner end of the piston 
is formed with a knife 9, and the piston further is provided with a 
through passageway 10. The piston in its fully inserted position, is 
locked against axial translation relative to the coupling part 2b by means 
of a locking ring 11 provided in the recess 8 in the guide passageway 5 
and is sealed beyond the ring 11 by means of a sealing ring 12 abutting 
the wall of the guide passageway. In said position the passageway 10 is 
located on the same level as the connection 6, and the knife 9 is located 
to the side of the feed-pipe portion projecting into the guide passageway. 
The knife has a cutting edge 13, which extends in a first direction 
longitudinally of the piston from the tip of the knife alongside the 
feed-pipe at least to the same level as the shell surface of the feed-pipe 
which is located fartherest inwardly in the guide passageway. 
With a pipe coupling according to the embodiment described above, 
transversely directed pipes easily can be connected without interrupting 
the operation of the main pipe in transporting liquids or gases. When in 
the aforesaid assembled position of the pipe coupling, the piston 4 is 
turned clockwise through one revolution, for example by a key in the 
socket 14, the knife 9 cuts a first hole into the feed pipe 1 in its pass 
from one side to the other and cuts a second hole in its pass from the 
other side back to the one side. The knife 9 and its cutting edge 13 may 
have different shapes for cutting holes of different shapes. An the 
embodiment shown, the knife has "plough-shape", and the cutting edge 
extends in a second direction transverse to the wall of the passageway 10. 
By this knife shape two spaced holes 15 with an intermediate bridge 16 are 
obtained. Besides, the material cut-up from the feed-pipe is not detached, 
but is folded upward into the widened portion 7 in the guide passageway 5 
and is retained in said portion as indicated by reference numeral 17, so 
that the cut-away part is not carried away by the flow. Due to the fact, 
that the cut-up material does not project into the flow and does not 
disturb the flow, by being folded downward into the same, an effective 
fixing anchoring of the pipe coupling in its position on the feed-pipe is 
obtained by the folded-up material 17. 
The piston 4, subsequent to the cutting operation, serves as a valve body 
for controlling the flow rate through the pipe connection 6. In 
conventional pipe couplings with valve bodies it has been a problem to 
achieve fully satisfactory sealing when the flow between feed-pipe and 
branch pipe was shut off. In the embodiment according to FIGS. 1-4, as 
shown, the problem has been solved by simple means. The piston 4 is 
provided with a sealing plug 18, which by a spring washer 19 located 
inside of the sealing plug is maintained pressed outward, whereby after 
the turning of the piston 4 for closing the opening between the connection 
6 and passageway 10 the spring-loaded sealing plug registers with the 
opening of the connection 6 and ensures flow shut-off. 
In FIGS. 5-7 an embodiment is shown where the connection for the branch 
pipe extends in the same direction as the flow passageway of the piston, 
which passageway in its turn extends throughout the length of the piston 
in the same direction as the cylindrical guide passageway of the coupling 
part. As appears from the drawings, details corresponding to those of the 
embodiment shown in FIGS. 1-4 have been given the same reference numerals 
followed by a prime. 
In this embodiment a valve body 20 with a through passageway 21 is inserted 
in the piston 4'. The valve body is rotatably adjustable between a 
position, in which the flow connection between the feed-pipe 1' and the 
branch pipe 6' through the passageway 21 is fully open, and a position, in 
which the connection between said pipes is fully closed. Said rotation can 
be effected, for example, through a hole 22 in the coupling part 26' for a 
screw driver to co-operate with a slot 23 in the valve body 20. 
The invention, of course, is not restricted to the embodiments described 
above and shown in the drawings, but can be varied in several ways within 
the scope of the attached claims. The pipe coupling, for example, can be 
designed for the connection of more than one branch pipe, and the knife 
may be formed to cut, for example, a complete hole in the feed pipe. The 
essential feature of the invention is the simple and efficient making of 
holes in the feed-pipe by simply rotating the knife-carrying piston 
whereby also large flow holes relative to the dimension of the feed-pipe 
can be obtained. It also renders possible an efficient locking of the pipe 
coupling to the feed-pipe by folding-up the material cut-up at the hole 
making. A further essential property of the invention is the efficient 
sealing by the spring-loaded gasket or plug when the flow between the 
feed-pipe and branch pipe is being shut off.