Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1 3 I Q ~ 7 1~ ~
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Coupling, in particular a quick-acting coupling
for fluid conduits
The invention relates to a coupling, in particular a
quick-acting coupling for fluid conduits according to the
classifying part of Claim 1.
Couplings of this type are used in particular to effect the
rapid, tight connection of hoses or other flexible fluid
conduits.
A coupling of this type is described in Swiss Patent No.
CH-A-626 696. This has two sealing members one of which is
designed as a spigot valve and the other as a socket valve, each
having a coupling section that may be brought by means of a
spring into the closed position which presses in each case
against a seal ring in a sealing position on an inner conical
surface of the sealing member. The seal between the two sealing
members is achieved by a further seal ring of resilient material
pressed together by the sealing members. In the coupled state,
the coupling section can be locked in the release position by
means of a locking pin so that, for example, there can be no
axial movements beyond its release position in the event of
pressure surges. This is intended, in the most unfavourable
circumstances, to prevent the valve from shutting down, thereby
completely blocking the entire system. The two sealing members
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are locked together by means of locking balls, which, in the
coupled position, each lie in a groove of a sleeve and of the
spigot valve. The presence of additional grooves in a sleeve
which can be slipped over the connecting part of the spigot and
socket valve makes it possible to bring the balls into a non
locking position, it being necessary to displace the locking
balls when coupling up and uncoupling, a process which could
cause problems, for example as a result of soiling or jamming.
Sealing rings wear out relatively rapidly and the resultant
leakage causes damage whlch can only be prevented by frequent,
regular maintenance (replacement of the sealing rings). To
change the sealing rings the entire coupling has to be
dismantled, which is laborious and time-consuming and
necessitates lengthy closing down of the plant in question.
Resilient sealing rings cannot be used for aggressive fluids or
gases, at high, low or widely fluctuating temperatures or where
radioactive radiation is present. It has hitherto been
impossible to use any couplings of this nature in such
situations. A further disadvantage of conventional couplings of
this type is their large number of components, rendering them
unreliable and expensive.
Further couplings of this type are described in French
Patent No. FR-A-1 288 938 and Swiss Patent No. CH-A-474 010.
~hese have sealing, conical surfaces against which a resilient
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sealing lip is pressed. Frequent opening and closing of the sealing members causes wear
on the resilient lip and/or the conical surface, impairing the tightness of the entire
coupling. If these couplings are only infrequently opened, the sealing lip pressed thereto
tends to adhere to the opposing surface so that it is generally impossible to release the
coupling without darnaging it. Moreover, dirt can be pressed between the conical surfaces
when the two sealing members are pressed together, also rendering adequate tightness
impossible.
It is an object of the invention to provide a maintenance-free coupling of simple design
which can also be used with aggressive fluids and over a wide temperature range. ~
particular, the coupling should be capable of functioning at high, low or widely fluctuating
temperatures, in the presence of radioactive radiation, severe ambient conditions as well as
underwater.
According to one aspect of the invention there is provided a coupling for fluid conduits,
comprising a first and a second coupling member, said first coupling member including a
first hollow space and said second coupling member including a second hollow space to
be connected to the respective fluid conduits, said first and said second hollow space each
having a front wall, said first coupling member having an annular projection with a
cylindrical outer metallic sealing surface, said second coupling member having a first bore
with a cylindrical metallic sealing surface, said cylindrical outer metallic sealing surface of
said annular projection fitting in said cylindrical metallic sealing surface of said first bore
such that in the coupled state the two metallic sealing surfaces tightly adjoin to one
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another and are separated from one another only by a clearance fit being so small that the
fluid cannot escape between the sealing surfaces, said first coupling member including a
second bore with a cylindrical metallic sealing surface extending axially throughout said
annular projection and through said front wall into said first hollow space, said second
coupling member including a third bore with a cylindrical sealing surface extending from
the rear end of said first bore through said front wall into said second hollow space, a first
and a second closure bolt for closing the first and second coupling member in the
uncoupled state and opening them for communication with one another in the coupled
state, said first and second closure bolt having a port and guide front part and a cylindrical
sealing back paTt, the first port and guide front part as well as the first sealing back part
being designed to slide in the second bore and the second port and guide front part as well
as the second sealing back part being designed to slide in the third bore, the first and
second cylindrical sealing back part each being provided at its rear end with a stop, Iying
in the first and respectively second hollow space and loaded by a spring connected to urge
the stop towards the front wall of the first and respectively second hollow space, the first
and second port and guide ~ont part abutting one another during coupling and thereby
being pushed backwards against the forces of said springs, so that they are Iying in the
coupled state in the second and respectively third bore, the port and guide front part being
so designed that on the one hand it slides and is thereby guided in the second and
respectively third bore and on the other hand fluid can flow therethrough, the first and the
second sealing back part each having a cylindrical outer metallic sealing surface fitting in
the cylindrical rnetallic sealing surface of the second and respectively third bore and Iying
in the coupled state in the first and respectively second hollow space and, in the uncoupled
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state, tightly in the second and respectively third bore, the metallic sealing surfaces of the
sealing back parts and the second and respectively third bore being separated from one
another only by a clearance fit being so small that the fluid cannot escape between the
sealing surfaces.
The advantage of the invention lies substantially in the fact that, contrary to prevailing
practice, the tightness of the sealing members is effected without resilient sealing rings,
conical sealing surfaces or resilient sealing lips, eliminating the need for maintenance and
permitting a construction that is simpler than that of conventional couplings, with fewer
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components that thus requires fewer handling and processing
steps during assembly and manufacture.
Preferred embodiments of the coupling of the invention are
set out in claims 2 to 15.
There now follow more detailed descriptions of embodiments
of the coupling of the invention with reference to the drawings.
There are shown in:
Fig. 1 a longitudinal section through a quick-acting coupling
in the uncoupled position,
Fig. 2 a longitudinal section through the coupling in coupled
position,
Fig. 3 a side view of a coupling section of the coupling,
Fig. 4 a view of the coupling section along the direction IV
shown in Fig. 3, and
Fig. 5 a longitudinal section through a variant of the
coupling in the uncoupled position.
_ 5 _ 1 3 1 0 ~ 7 6
The quick-acting coupling shown in Figures 1 to 4 is used to
join flexible conduits through which a fluid such as water or
oil flows. It consists of two sealing members 2 and 3, the
coupling member 2 being formed as a socket valve and the
sealing member 3 as a spigot valve. All components down to the
springs 6, 19 described below as well as spring clips 14 and a
locking ring 13 are made of the same material in both sealing
members 2 and 3, preferably of steel and, in particular, of a
corrosion-resistant steel of high degree of hardness; their
coefficient of thermal expansion is therefore the same. It is
necessary to use materials having the same coefficient of
thermal expansion in order, as will be described below, to
maintain a clearance fit of the sealing surfaces and hence their
clearance gap width without developing into an almost
inseparable press fit or a leaking fit in the event of
fluctuations in the temperature of the environment or of the
fluid. Each of the sealing members 2 and 3 has a coupling
section 5 and a helical spring 6 as a sealing spring. The outer
diameter of the helical spring 6 is so selected that it is a
close tolerance fit in the diameter of a bore 35 or 36 to be
described below.
The socket valve 2 has a socket part 10 with an outer
coaxial bulge 12 in the vicinity of its front portion 16
directed towards the spigot valve 3 during coupling which,
looking along the forward portion 16, follows a groove 15. The
6 131~7v
spigot valve 3 has a spigot part 11 as well as six spring
tongues 14 having hook-shaped notches at their free ends welded
onto a slit locking ring 13, said notches extending beyond the
forward portion 18 of the spigot part 11 over which a sleeve 17
can be slid by means of a helical spring 19. One closure cap 7
is tightly screwed onto each of the socket part 10 and the
spigot part 11.
The slit locking ring 13 is securely held in a coaxial
groove 20 of the spigot part 11. The helical spring 19 lies with
a clearance fit over the locking ring 13 and a part of the
length of the tongues 14. One end of the helical spring 19 abuts
against a shoulder 24 of the spigot part 11 as a radial
extension of the edge of the groove 20 facing away from the
forward portion 18, the other end i5 supported on an inner,
substantially coaxial shoulder 29 of the sleeve 17 about in the
middle thereof.
In order to effect coupling, the sleeve 17 is retracted
manually against the force of the spring 19, the tongues 14
being resiliently flexible and capable of being pushed over the
bulge 12 until they seat in the groove 15. The sleeve 17 is
pushed back over the tongues 14 by the force of the spring 19
making it impossible for the tongues 14 to bend radially
outwards; both sealing members 2 and 3 are thereby secured in
such a way that they cannot slide apart. In the coupled and in
1 3 1 0~76
the uncoupled position, the shoulder 29, extending from the
locking ring 13 rests against a first bend of the tongues 14
looking away from the coupling axis. The sleeve 17 is thus
prevented from sliding downwards, but can be pushed over the
spring tongues 14 by exerting increased pressure for purposes of
assembly and disassembly.
At its forward portion 16 the socket part 10 has a coaxial,
annular projection 21, and the spigot part 11 has at its forward
portion 18 an inner coaxial annular projection 22 and an outer
coaxial annular projection 23, between which a ring groove is
formed. The projection 21 has two 25 and 26, circular
cylindrical surfaces, the inner projection 22 one 27 and the
outer projection 23 one 28. When the sealing members 2 and 3 are
connected together, the surfaces 25 and 27 as well as 26 and 28
lie in pairs against each other with clearance fits. Between the
two surfaces 25 and 27 there is a maximum gap of 5~um; this even
renders the coupling helium-tight (if the coupling is used, for
example, for water, less stringent demands are made of the
maximum gap width). The casing lines of the circular cylindrical
casing surfaces 25, 26, 27 and 28 are parallel to the axis of
the socket and spigot valve 2 or 3 and thus also parallel to the
coupling axis and should have as little taper as possible; taper
may only be a maximum of a few angular minutes. This small taper
may not be exceeded since otherwise the socket value could jam
in the spigot valve when being used as a quick-acting coupling.
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The socket part 10 and the spigot part 11 each have a
coaxial bore 31 or 32 which, when coupled together, are flush
with one another, are aligned with one another and have the same
diameter. The edges of the bores 30 and 31 are sharp corners
without any burr. The length of the bore 31 corresponds
substantially to one and a half times its diameter and is
somewhat longer than the casing length of the surface 25 or 27.
As described below, the length of the bores 31 and 32 as well as
the casing lengths a of the surface 25 or 27 shown in Fig. 1
depend on the finishing tolerances and the desired sealing
effect. The bore 31 passes at its end facing the forward portion
16 angularly into a bore with the coaxial inner surface 25, the
inner diameter of which is the same as the outer diameter of the
annular projections 22 apart from a clearance fit. The bore 32
continues in the annular projection 22. Its total length is
substantially the same as the sum of the length of the bore 31
plus the casing length of the surface 25.
The bores 31 and 32 extend respectively beyond a radial step
surface 42 perpendicular to the bore hole axis into further
bores 35 and 36, the diameters of which are substantially the
same; the bore hole axes and the axes of the sealing members are
identical. The diameter of these bores 35 and 36 is determined
in construction by the diameter of a hat 39 (described below) 39
of the coupling section 5 and the diameter of the helical spring
1 3 1 0 ~76
6 adapted thereto. The lengths of the bores 35 and 36 derive
from the length of the fully compressed helical spring 6 plus
the thickness of the hat 39 plus the length of a fitting 40
(described below) of the coupling section 5 plus a few
millimetres b which, as will be described below, are necessary
to enable fluid to flow through a port and guide member 41
(described below) of the coupling section 5.
As shown in Figures 1 and 2, the closure cap 7 is in
one-piece with a coaxial screw nipple 43 connected to a coaxial
hexagonal nut 44. In the centre of the screw nipple 43 is a bore
47 which extends in a radial wall 49 perpendicular to the axis
of the bore hole into an axial internal thread 50 inside the
hexagonal nut 44. The closure cap 7 is screwed as described
above to the socket 10 and spigot part 11 respectively by means
of their inner threads 50 by means of an external thread 52 on
the portion facing away from the forward portions 16 or 18. In
the assembled state, the closure caps 7 sit securely on the
socket 10 and spigot part 11. Sealing is achieved by the wall 49
to which the forward portion of the socket 10 and spigot part 11
facing away from the forward portions 16 or 18 is pressed. To
make it possible to screw on and subsequently unscrew the
closure cap 7 firmly to the socket 10 and spigot part 11
respectively they are shaped in the same way as the
circumferential surfaces 54 or 55 of the socket 10 and spigot 11
i.e. in the form of a hexagonal nut 44, as mentioned above.
lO - ~ 3 1 0~76
A flexible conduit or a hose (not shown) is secured to the
appropriate sealing member 2 or 3 in each case to one of the
screw nipples 43 of the closure cap 7 shown in Figures 1 and 2.
Instead of a screw nipple 43 it is also possible to provide a
hose connection that is retained firmly using a hose clip.
The dish-shaped hat 39, together with a cylindrical bolt
serving as`the stem, forms the mushroom-shaped coupling section
5. The surfaces of the underside 53 and upper side 60 of the hat
are substantially parallel to one another and lie perpendicular
to the axis of the stem. Cut out of the dish-shaped hat 39 are
two opposing circular segments 57 which serve as the throughflow
space for the fluid. In the uncoupled position, the underside 59
of the hat 39 is pressed against the stop surface 42 by means of
the helical spring 6. The upper side 60 of the hat 39 supports
one end of the helical spring 6. The stem has three semicircular
recesses 56 about its circumference along two thirds of its
length facing away from the hat 39. The cross sectional surfaces
of the two circular segments 57 and the three recesses 56 are
substantially identical; the fluid flows therethrough in the
coupled state. The fitting 40 is designed as a circular cylinder
and is about only one third of the length of the port and guide
member 41. These length ratios were selected to enable the fluid
to flow into and out of the three recesses 56 at a distance b
between the end of the fitting 40 and the surface 42, as may be
seen in Fig. 2.
" I~I06,')
In Figures 1 and 2, the coupling sections 5 are rotated
about their stem axis by 90 degrees as compared to the
representation in Figure 3 in order to show more clearly the
free or blocked path of the fluid inside the coupling.
The port and guide members 41 of the coupling sections 5 lie
aligned with one another in the coupled state. The coupling
sections 5 are freely rotatable in the bore 31 or 32 and the
sealing members 2 and 3 are also rreely rotatable during
assembly. It is consequently not possible to predict how the
crosspieces between the recesses 56 will match up in the coupled
state. The port and guide members 41 have on their forward
portion a bezel 58. This prevents fluctuations in flow when the
recesses 56 are rotated against each other.
In the uncoupled state, as shown in Fig. 1, the fitting 40
of the coupling section 5 is inserted with a clearance fit of
preferably at most 5~um when water is the fluid and steel is the
material of the sealing parts with a pressure difference to be
retained of a few tens of atmospheres in the bores 31 and 32
respectively The size of this gap varies according to the
pressure difference of the fluid to be contained, the viscosity
of the fluid, the length of the fitting 40 and the utilizable
spring force of the helical spring 6. As in the case of the
surfaces 25 to 28, the taper of the fitting 40 and the bores 31
and 32 may not exceed a few angular minutes.
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The gap is on the one hand wide enough to allow the easy
sliding of the coupling section 5 and, on the other hand, narrow
enough to ensure adequate sealing to the outside of the fluid in
the bore 36. The coupling section 5 must be pushed forward
during uncoupling by means of the sealing spring 6 as fast as
the two sealing members 2 and 3 are pulled apart. This would be
possible at any time with a sufficiently large spring force, but
the spring force may, however, only be large enough to enable
the two coupling sections 5 to be pushed together with a normal
force of a few Newtons, as achieved without effort by pushing
both hands against each other.
In the above described example the clearance fits providing
the seal are so designed that they are a maximum of five
micrometres in the case of a single sealing pair of surfaces, as
between the fitting bore 31 or 32 and the corresponding fitting
40. In the event of several radial, intricately arranged sealing
surfaces, as in the case of the surface pairs 61/62, 25/27,
63/64, 26/28, 65/66 the clearance fit can be up to one tenth of
a millimetre.
The sealing effect of the coupling surprisingly achieved
without any resilient sealing rings and without sealing surfaces
pressed against one another may perhaps be explained as follows:
there is a fil~ of fluid in the ring gap between the bore 32 and
_ 13 _ 1~6,~
the fitting 40 which adheres as a result of its adhesive force
both to the inner wall of the bore 32 and to the fitting piece
40. The friction of the fitting piece 5 inside the bore 32 is
analagous to the friction of a lubricant in a trunnion bearing.
It is proportional to the coefficient of viscosity of the
sliding surface, the speed with which the coupling section 5 is
moved and reciprocal to the gap width. The flow rate through the
gap is proportional to the pressure gradient between inner and
outer pressure, the cross section surface of the gap, the
quadrant of the gap width and reciprocal to the coefficient of
viscosity. The coefficient of viscosity depends on the
temperature of the fluid and its pressure. In summary, it is to
be assumed that the surprising sealing effect is based on the
adhesive force and the properties (coefficient of viscosity,
...) of physically non-ideal fluids.
To prevent the coupling section 5 jamming as it moves
backwards and forwards it must be exactly guided to ensure the
high degree of accuracy demanded of it. The exact guidance is
achieved by means of accurately fitted surfaces of the
crosspieces between the recesses 56.
The surfaces 25 and 27, as well as 26 and 28 seal the flow
passing between the two sealing members 2 and 3. As already
states, their tolerances are of the order of micrometres. The
accuracy of these surfaces may be smaller since the seal is
- 14 - ~ 3 1 ~6 i 6
achieved in a radially intricate manner by means of the two gaps
between the surfaces 25/27 and 26/28, as well as through an
additional gap between two radial surfaces 61 and 62 the bore 32
to the surface 27 and of the bore 31 to the surface 25 and a
further gap between two radial surfaces 63 and 64 of the surface
27 to the surface 28 and from the surface 25 to the surface 26,
as well as through the surface 65 radially adjacent to the
surface 26 or the adjacent surface 66 radial to the surface 28.
The sealing effect of these pairs of surfaces 25/27, 26/28,
61/62, 62/63 and 65/66 is further improved since the flow
passing therethrough exerts a suction effect on the fluid
present in the gaps.
During uncoupling, the sleeve 17 is pushed back by hand and
the two sealing members 2 and 3 are pulled apart against the
clampinq force of the tongues 14 on the bulge 12. The helical
spring 6 presses both coupling sections 5 substantially evenly
out of the corresponding sealing members 2 and 3. Both port and
guide members 41 touch each other at their forward portions, the
corresponding fitting 40 is slid into the corresponding fitting
bore 31 or 32 and thus seals in the fluid in the conduit system
behind the appropriate sealing members. The sealing members are
only pulled so far apart that there is no longer any sealing
effect of the surface pairs 25/27, 26/28, 63/64, 65/66, 61/62
when about two thirds of the overall length of the fitting 40 is
situated about two thirds inside the fitting bore 31 or 32.
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There is no spurting during uncoupling since sealing is achieved
before the sealing surfaces of the coupling have been completely
separated from one another. The coupling sections 5 then slide
further into the fitting bores 31 and 32, until the undersides
59 of the hats 39 abuts on the surfaces 42.
During manufacture of the components for the two sealing
members 2 and 3, care is taken to ensure that the surfaces 26
and 28, as'well as in particular 25 and 27 are coaxial to each
other and are as free of taper as possible. The taper may not
exceed a few angular minutes since a higher value would impair
the operability of the coupling and would, in the case of larger
pressures, cause jamming when the sealing members are pulled
apart. An advantage of these coaxial surfaces is that any dirt
adhering to the surfaces 25/27 and 26/28 respectively is pushed
aside when the sealing members 2 and 3 are pushed together.
It has been found in practical experiments that the sealing
effect is still preserved when the sealing members are pulled
apart up to substantially half the casing length of the surface
25 or 27. Sealing is thus achieved by the above described design
of the two surfaces 25 and 27.
The situation is analagous for the seal of the coupling
section 5, it also being necessary here to avoid any taper in
the casing surface of the fitting 40 as well as the axial
fitting bore 31 or 32.
- 16 - 1 3 1 ~ ~ "~
Instead of the hat 39 having the above-described shape, it
may also have a number of bores, the axes of which run
substantially parallel to the axis of the stem or which are, for
example, shaped like a small cross. Its function is to serve as
a support for one end of the helical spring 6 and to abut in the
uncoupled state against the surface 42 so that the helical
spring 6 does not push the coupling section 5 out of the
corresponding sealing members 2 or 3. Otherwise, the hat 39
would have to be shaped in such a way that the fluid can flow
through or alongside it.
Ins'ead of the three recesses 56 is is also possible to use
several recesses as well as also differently shaped recesses to
those shown. It is only necessary to ensure the guide properties
and an adequate throughflow. The form shown has, however, proved
to be optimum.
Instead of six spring tongues 14 it is also possible to use
three, four, five or more than six tongues. Six tongues
nevertheless ensure good guidance when pushed together.
If the coupling does not have to fulfill very high sealing
requirements, the sealing surfaces 26 and 28 may be omitted in a
simplified construction.
- 17 - 1 31 ~6,!)
Instead of the spring tongues 14 which prevent the two
sealing members together with the spring-loaded sleeve 17 from
sliding apart, it is also possible for a sealing member 70 to
have a thread 71 and the other sealing member 73 to have a
spigot nut 74 fitting thereto, as shown in Fig. 5. The spigot
nut 74 has a coaxial shoulder 75 and the sealing member 73 a
radial shoulder 76, the diameter of which is larger than the
inner diameter of the radial shoulder 76. sefore the hose is
fitted, the spigot nut 74 is pushed over the corresponding
sealing member 73.
Instead of the circular cylindrical shape of the annular
projections 21, 22, 23, the sleeve 17 and the arrangement of the
tongues 14 it is also possible to select an asymmetrical shape,
e.g. a kidney shape. An asymmetrical shape lays down the
corresponding position of the sealing members 2 and 3 to each
other. In addition, if the radial position of the coupling
section 5 to the corresponding sealing member 2 or 3 is
established in such a way that the recesses 56 of the two port
and guide members 41 align with one another, optimum throughflow
is always present in the coupled state. The radial position of
the coupling sections 5 can, for example, be fixed in that the
hat 39 has grooves or bulges (not shown) about its edge which
run in projections or depressions of the bore 35 or 36 (not
shown).
1 31 0 ~71~)
- 18 -
If the annular projections 21, 22, 23, the sleeve 17 and the
arrangement of the tongues 14 are of different shape, e.g.
kidney, triangular or rectangular, differing from the circular
cylindrlcal shape, it lS possible to manufacture couplings
having non-interchangeable sealing members. This makes it
possible to install entire coupling batteries which eliminate
the risk of confusing individual sealing members and
interchanging the fluid flows. If the sealing surfaces 25/27 and
26/28 are hot composed of circular cylindrical surfaces, but of
circular cylindrical and flat right angular part surfaces or
only of prismatic surfaces, then the casing lines of the annular
partial surfaces and/or the partial surfaces or prismatic
surfaces lie parallel to the axes of the socket or spigot valves
2 or 3. Instead of using different ~hapes it is also possible to
use different diameters. The couplings can, moreover, be coded
by providing matching holes and pins in one or more of the
surfaces 61, 63, 66 of the spigot part 3 and one or more of the
surfaces 62, 64, 65 of the socket part 2 fitting thereto. It is
also possible only to provide threaded holes in the surfaces 61
to 66 for the user to screw pins and grub screws into the
appropriate holes flush with the surface in order to produce the
coding desired.
If the coupling section 5 and the helical spring 6 are not
used for the quick-acting coupling, this coupling may also be
used as a simple coupling to join pieces of conduit.
- 19 ~ ~ 3 1 0 6 7G
Flow rate may be adjusted through the size of the area of
cross section of the recesses 56. In other words, the flow rate
can be set by inserting a coupling section with an area of cross
section corresponding to the recesses 56.
Instead of the fitting bore 31 or 32 it is also possible to
design the bores 35 and 36 as fitting bores. The hat 39 of the
coupling sèction 5 is then axially designed by analogy with the
fitting 40 and the port and guide member 41. It is also possible
for the bores 31 and 32 or 35 and 36 to be designed in such a
way that they assume the fitting and guiding functions. These
bores then have axial notches (not shown) on the inner surface
of their part facing away from the forward portion 16 or 18
which directs the fluid in the coupled state. The remaining part
of the bore is designed as a fitting. If the hat is designed as
a fitting, port and guide member, the sealing spring 6 must be
designed as a central spring which no longer abuts against the
rim of the hat. This solution involves a more complicated
construction and it is harder and more laborious to make the
exact fits to the large bores 35 and 36 than to the bores 31 or
32.
The coupling section 5 acts as a variable pressure reducer
due to its staggered mushroom-shaped design. During uncoupling
there is a continuous fall in pressure which prevents excessive
surges in the conduit system to be detached.
- 20 - 1 3 1 067b
Due to the particular design of the coupling it is possible
to avoid inner threads which would hinder flow. Care has, in
particular, been taken to provide the bore 35 or 36 with smooth
inner walls.
As already mentioned, a substantial advantage of the
coupling or quick-acting coupling of the invention as compared
to conventional couplings lies in the elimination of resilient
sealing elements which have to be specially exchanged and which
wear rapidly, depending on the fluid passing therethrough, on
the ambient temperature and conditions.
Instead of being made from the same steel, the sealing
surfaces 25/27, 26/28, 31/40, 32/40 and the coupling section 5,
the socket and spigot part 10 and 11 may be made from brass or
aluminium treated in the same manner, in particular
surface-treated. Instead of the same hard metal, the coupling
section 5 and the socket and spigot parts 10 and 11 may be
composed of hard plastic or may just be plastic-coated.
During coupling, care is taken to obtain a smooth
throughflow without gap and corners in which material could
become deposited. For this reason the coupling is particularly
suitable for the food sector. It may also be used in the
chemical industry and in the laboratory.
- 21 - 1 3 1 0 67G
sy means of appropriate design of the front portion surfaces
61 to 66 and 25 to 28 of the socket and spigot valve 2 and 3 it
is also possible to pass gaseous fluids through the coupling.
The quick-acting coupling described in claim 6 ana in claim
8 may also be made of lightweight metal, for example aluminium.
A groove may, for example, be provided for insertion of a
sealing ring, preferably in a corner formed of the two surfaces
27 and 63 or 25 and 62. It is also possible for the coupling
section 5 to have a groove for a sealing ring, preferably in the
corner formed of the underside of the hat 59 and the fitting 40.
