Note: Descriptions are shown in the official language in which they were submitted.
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FENDER STRUCTURE
The invention relates to fender structures. The preferred applications for the
fender structures according to the invention are also described.
Fender systems are used for the energy-absorptive protection of objects, such
as motor vehicles and other materiel, which are exposed to dynamic stresses.
A typical application for fenders is the protection of boats which come into
contact with one another or which are moored at jetties, in pontoon enclosures
or to
shore.
Another related area of application is, for example, to protect, support and
stay
general cargo in transit, such as in cargo holds in ships, in containers or on
lorries.
The fleet of pleasure boats and corresponding jetty installations are growing
at a
great rate and represent considerable assets. Each year insufficiently soft,
energy-
absorbing fendering of boats and jetties leads to considerable damage to boat
hulls.
If jetties and pontoon enclosures include fenders they are usually in the form
of
plastic profile extrusions etc. which do not have the desired softness and
energy-
absorbing effect. Marinas are designed and constructed in many different ways
and
there is a great need for a soft, energy-absorbing, easy-to-mount fender
system which
is suitable for mounting to the various types of facilities.
The use of soft, energy-absorbing fender systems is well-known, and in this
regard, reference is made to US patent 3,305,259 which discloses a shock-
absorbing
fender containing a continuous gas-containing elastic tube, which is divided
into
compartments hermetically sealed from each other. However, as the individual
compartments are mutually hermetically sealed, the structure is unable to
provide
shock-absorbing properties as intended with the present structure. As the
compartments are filled with air during extrusion of the tube, there is not
further
possibility of air pressure adjustment after the tube/fender has been
produced. Further,
there is no kind of "throttle valve" functions, and in applications where "on-
force"
deformations can take place, this might easily lead to puncturing of the
compartments.
A further disadvantage is the difficulty to obtain a sufficient air pressure
inside
each compartment. The physical explanation for this is that the extruded tube
(rubber or
thermoplastic) is in a very soft "melt phase" (around 200 C) as it is filled
with air. The
inside air pressure in the tube must be rather low to avoid that the melt
expands
unintentionally. As the hot air inside the tube/compartments cools off, the
air pressure
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will be correspondingly reduced. Obviously the forming of the soft extruded
melt has to
take place in apressure-chamber" to be able to reach an air pressure inside
the tube
that is higher than the atmospheric pressure after cooling down the tube to
ambient
temperature.
Further, the prior art fender-system can not be deflated and transported in
compact rolls, and shipment as well as storage (by local dealers) will be more
expensive. The practical use of the prior art solution is rather limited
compared with the
fender of the present invention.
The structure of the present invention does not face the above mentioned
problems as the air pressure in the compartments can be adjusted within close
tolerances at any time after production
The most commonly used soft and energy-absorbing fender systems however
are formed as individual, hollow bodies filled with air or plastic foam, and
their
geometric design varies between a cylindrical form and a spherical form of
limited
length per unit. Such traditional fenders are hung along the side of the
vessel and/or on
the jetty with rope, fixing brackets or similar. However, fenders of the
individual buoy
type provide no uniform, flexible solution for the many different types of
craft which a
marina is intended to serve.
For further information about the status of the technology with regard to
fenders,
please refer to the many boating magazines which are available, such as the
magazine
"Batmagasinet" and catalogue material such as "Maritime".
An object of the invention is to produce a new fender system which overcomes
all the above-mentioned disadvantages.
A further object of the invention is to produce a fender system which is of
simple
construction, which is simple to mount, and which is reliable.
The fender structure according to the invention is characterized in that each
chamber has a fluid connection with the adjoining chamber or chambers.
According to the invention the device is used to provide energy-absorbing
protection of objects such as motor vehicles and other materiel which are
exposed to
dynamic stresses, such as vessels (pleasure craft) which come into contact
with one
another, or are moored at jetties, in pontoon enclosures or to shore, and/or
to protect,
support and stay general cargo in transit, such as in cargo hold of vessels,
in containers
or on lorries. The fender system according to the invention is also well-
suited for use on
tug boats, supply vessels, rescue vessels and similar.
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The present invention describes a product in the form of a fender which is
particularly energy-absorbing and suitable for a variety of shock absorbing
applications
while at the same time being easy to mount on jetties and marina facilities.
If a single
chamber in the fender system is compressed, the air in the chamber is
simultaneously
forced out through the openings/holes in the connecting areas between the
chambers
and into the adjoining air chambers on each side. The flow resistance which
arises
when the air is forced out gives the mentioned energy-absorbing effect. When a
through-running flexible tube is used between the chambers, where the tube
includes
one or more outlet holes in the tube wall, the air must first be forced into
the tube
through the holes and then be forced onward through the tube to the adjoining
chambers.
According to the invention, the fender is in the form of an "infinitely long
"chain of
linked, soft, energy-absorptive (air-filled) elements, and for delivery to
market may be
coiled on a roll or drum. The fender can be cut to the desired length to fit
the place
where it is to be mounted and the entire length can be filled with air from
only one filling
valve, which can be devised in an easily accessible place (with the duct/tube
at each
end of the fender then being plugged/sealed). The fender can be bent around
comers
and edges, and can be largely made to fit the contours of the base in
question.
The fender can be fixed to a large number of different constructions which
require shock-absorbent protection, i.e. constructions above and/or below
water and in
all desired directions.
According to the invention, the area where the fender system can be fixed to
the
base is recessed and thus protected against rubbing and/or contact.
The fender according to the invention may be produced from a number of elastic
materials, including thermoplastic polyurethane (TPU), which is one of the
most durable
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and flexible materials in cold as well as warm conditions that is currently
available. The
material commonly used today in rubbing strakes and fenders is soft PVC, which
in the
context mentioned here does not have the same excellent mechanical properties
as the
preferred material TPU.
All thermoplastic materials, as well as rubber materials and cross-linked
materials,
can be used.
The fender solution may easily be glued and/or welded, thus permitting any
damage
to be repaired, and it can also be cut and spliced with splicing pieces which
are pressed or
glued into the inner tube.
The solution provides a particularly good energy-absorptive effect because,
being
filled with a gas or liquid, it functions as a dynamic unit in which the
chambers work
together with the help of a specially designed, built-in" pressure control
system".
This "pressure control system "functions as individual throttle valves or
check valves
for each chamber, where the throttle can be adjusted depending on the design
of the valve
system. in all variants ranging between soft dampening, where the ducts are
open
particularly wide, and a tight seal if the tube is designed with a check valve
which does not
let the air out of the chamber again once it has first entered.
In applications where the fender is exposed to particularly high stresses, the
fender
system can be filled with a liquid which subsequently hardens to form a solid,
energy-
absorptive mass, including foam. Such a liquid can, for example, be two-
component or
multi-component polyurethane.
Through a choice of alternative filling materials and valve systems, the
fender
system can be adapted to satisfy various requirements with regard to energy-
absorbing
properties, proof against puncturing and mechanical strength.
The solution according to the invention can furthermore be dimensioned within
a
variety of parameters to achieve the desired energy-absorbing effect. In the
case of small
jetties and pontoon enclosures, as well as vertical-walled quay structures,
the fender
according to the invention can be mounted as desired, either vertically,
horizontally or
crosswise, etc.
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The energy-absorbing fender's design permits it to be used as a fender around
a
boat hull. The bow and gunnels of a boat are particularly vulnerable to wear
and tear and
this fender design can provide better protection for such areas.
A soft fender is achieved by producing energy-absorptive chambers. In order to
make the fender easy to mount, the chambers are produced with a flat, compact
area
between each chamber, enabling the fender chain to be fixed to a base in a
number of
different ways, such as for example using strips, nails, screws, rope,
brackets etc.
When mounting, the fixing points will, as mentioned in a previous paragraph,
be
recessed so as to prevent the hull from coming into contact with screw heads
and similar or
from rubbing and destroying fastening, strips, rope or other fixing means.
To make the chambers energy-absorptive, the volume, filling medium and
pressure
must be adjusted to the specific amounts of impact energy which may arise in
the (jetty)
facility in question. In order to achieve a combination of soft and controlled
energy-
absorptive effects, the different chambers are connected to one another so
that the flat,
compact areas and the chambers between these areas enclose a tube-formed check
valve
or throttle valve which connects all hollow spaces, dimensioned and shaped in
accordance
with the desired dampening and/or checking effect.
To achieve high strength and to avoid unwanted air leakage, the soft, energy-
absorptive fender can be produced in a single homogenous piece of material
without joints,
glue joints or similar, where the compact and flat areas, the valve system and
the hollow
spaces are permanently connected with one another.
According to a preferred embodiment of the invention, the fluid with which the
chambers are filled is a gas such as air, a liquid such as oil or water, or a
low-viscosity
crosslinking compound of plastic or similar which is cross-linked after
tilling.
To achieve an energy-absorbing fender with particularly high stiffness, the
connection between the different hollow spaces can be blocked when excess
pressure
arises in the chambers by enclosing the inner duct/line with an elastic tube,
and equipping
both the duct and the tight-fitting elastic tube sheath (stocking) with at
least one radial hole
in each chamber through which the valve system runs, and these holes are
displaced
axially in relation to one another so that they do not overlap. This will
allow air with excess
pressure to leak from the tube and into the space between the two tubes, and
be let out
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into the chamber through the holes in the outer stocking. This provides a
solution in which
air can be filled into the chambers but cannot get out again, as a result of
the mentioned
stocking.
The connecting duct or the tube-formed throttle valve and/or check valve is
enclosed
by, and permanently connected to, the surrounding material in the (flat)
compact area
between the hollow spaces. In the intermediate energy-absorptive chambers, the
connecting tube is only partly permanently connected to the surrounding
material (the wall),
i.e. it can be joined or attached to the inner wall of each chamber.
Alternatively, it can run
completely free and without contact with any of the inner walls which define
the chamber.
To avoid air leaking from one chamber into another apart from through the
duct/opening through the central part, the design ensures a tight seal between
the
chambers as the enclosing, tight-fitting tube sheath is permanently fixed to,
and forms a
homogenous material with, the compact (flat) areas between the hollow spaces.
The embodiment of the fender system functions as intended as a result of the
combined effect of the constructive design and the technical flow conditions.
The dynamic
effect will be determined by adjusting the size of the fender's chambers, the
pressure of the
filling medium, and the connecting duct's diameter and outlet cross section in
each
chamber, where the flat, compact areas and the hollow spaces between these
areas
enclose and are permanently connected to a "duct-valve system for transport of
fluid/filling
medium between the chambers.
The dynamic effect is achieved by designing the duct-valve system according to
the
desired energy-absorbing effect, by having the duct's outlets in the chambers
function as
throttle valves when the filling medium (air) flows between the individual
chambers, or as
check valves when the filling medium is not allowed to flow out of the
chambers but only in
the chambers.
A detailed description of the invention will now be provided with reference to
the
accompanying drawings, in which: FIGURE 1 shows a longitudinal drawing of the
fender
system according to the invention.
FIGURE 2 shows a detailed drawing of two chambers with a compact (connecting)
area between the two, i.e. from the same side as the longitudinal drawing in
Figure 1.
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FIGURE 3 shows a cross section, and partly in the form of a perspective, of
the
fender taken along the line A-A in Figure 2. The cross sections can have
different
geometric shapes and another preferred example is shown in Figure 7C.
FIGURE 4 shows a detailed drawing of two chambers with a compact area between
the two as in Figure 2, but where the tender is turned 90 .
FIGURE 5 shows a section of Figure 4, with a continuous line/tube running
through
the fender, and where one or more holes in the wall of the line/tube form a
fluid connection
between the inside of the line and the chambers.
FIGURE 6 shows a drawing analogous to Figure 5, where a line/tube with an
outer
stocking is run through the fender.
FIGURE 7A shows a side view of the fender system as a preferred embodiment
would actually appear.
FIGURE 7B shows a plane section of the fender system according to Figure 7A.
FIGURE 7C shows the cross section and the end view of D-D in Figure 7B.
The description will refer firstly to Figure 1, which shows parts of a
continuous
fender construction according to the invention.
The fender 10 is formed from a number of hollow, bag-shaped chambers 12 which
are defined by an elastic material, such as thermoplastic polyurethane (TPU),
PVC, rubber
or similar. The fender can be manufactured from a long hollow profile with the
desired
cross section form, which at regular intervals is compressed flat to form the
solid, compact
between-lying connecting areas 14. The hollow profile, which can have
different geometric
cross sections, appears in the present example with a mostly circular cross
section. Figure
7 shows a preferred example of the profile.
Between two connecting areas 14 the hollow profile forms a chamber 12 which
can
be tilled with a fluid, such as air or a liquid. A suitable thickness for the
wall of the hollow
profile would normally be in the region of 3-5 mm. With the help of compressed
air the
chambers can be "inflated", and the fender/through-going line can be sealed at
each end.
In Figure 2, a hollow line or tube 18 runs through the inside of each chamber
12 and
is embedded in the solid connecting area 14. In the tube 18 which runs through
each
chamber 12, a through-going hole 20 is formed in the tube wall. Here, the tube
18 can be
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partially connected to the inner wall of the chamber 12 or run free, i.e. so
that it has no
contact with the inner walls of the chamber.
Figure 3 shows a cross section, and partly in the form of a drawing, of the
fender 10
taken along the line A-A in Figure 2. The chamber-forming body 12 is made,
together with
the compressed central part 14, of solid plastic material. Figure 7 shows a
corresponding
section where the chamber-forming body 12 has a different geometric shape. In
this
embodiment, the wall and the compressed central parts 14 form a foot which can
be used
to fix the fender to the base. The fender is then laid with the foot side down
against the
base and can then be fixed to the base. As shown in Figure 7B, the central
part 14 includes
holes 34 for inserting fastening strips, screws/nails, and the like to fix the
fender to the
base.
The lineltube can be replaced by creating a duct or boring a channel through
the
solid material of the central part 14 between the chambers, alternatively in
the form of a
through-going embedded bit of tube, so that a fluid connection is established
between two
adjoining chambers 12.
Figure 4 shows a drawing analogous to Figure 2, but where the fender is turned
90 .
The chambers 12, the part 14 and the tube 18 are shown.
Figure 5 shows in greater detail how the tube 18 runs through the chamber 12,
and
the figure indicates the hole 20 in the tube wall.
Figure 6 shows a drawing analogous to Figure 5, where a line/tube with an
outer
stocking is run through the fender. The inner lineltube is shown at 18, while
the stocking,
which is of a dense, elastic material, is shown at 22. Both these two (line 18
and stocking
22) include a hole going through their respective walls. This is shown at 24
and 20. While
the inner line 18 can be of a relatively stiff but flexible plastic, the outer
stocking 22 is
elastic.
When filling the chambers with a fluid, such as air, this double tube system
18, 22
will function as follows: Compressed air is pumped into the tube 18. At a
given excess
pressure the outer elastic stocking 22 will be lifted out from the surface of
the tube, and the
air will flow into the space between the tube/stocking up to the hole 24 and
then out into the
chamber 12. When the pumping stops, and the pressure in the chamber 12 is
higher than
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in the line 18, it will cause the stocking to "cling" tight to the line 18,
and stop the air
returning the same way as it came in.
The inner tube thus runs through the entire length of the fender 10, and can
be
plugged at one end at 32 (Figure 7C). At the other end the tube can be
connected to a
source of compressed air in order to till the chambers. An ordinary car tire
valve mounted
in the duct can be used to plug the end, as indicated at 32.
With this fender system according to the invention, with the exception of the
embodiment according to Figure 6, the pressure (i.e. the air) will be
transmitted through the
entire length of the fender (via the line 18) when one or any chamber is
compressed. The
line's dimensions, the dimensions of each hole in the line, determine the
transmission of
the fluid and corresponding pressure build-up through the row of chambers. In
this way the
fender's capacity for absorbing impact energy can be determined to fit a large
variety of
applications. The embodiment of the invention in Figure 6 shows an embodiment
in which
maximum stiffness is achieved, since the air cannot flow back.
Figures 7A, 7B and 7C show a side view, a plane view and an end view
respectively
of the most preferred embodiments of the fender system according to the
invention. In this
solution the chamber-forming body 12 has a different geometric shape. Compared
with the
side-view drawing in Figure 3, the compressed central parts 14 are displaced
from the
central position and towards one side of the end-view drawing. The fender has
thus
acquired more of an oval section as is evident in Figure 7C. The compressed
central parts
14 thus form a foot 30 which can be used to fix the fender to the base. This
is the most
preferred embodiment of the invention because the solid central parts 14,
through which
fixing media such as nails, screws and similar can be inserted to fix the
fender to the base,
will have contact face to the mentioned base.
The principle on which the fender system is based is the same, irrespective of
what
the tender's chambers are filled with. A common inside filling valve is used
(32 in Figure 7),
where a number of connected chambers can be filled in one operation, and where
the
fender's total dampening characteristics can be "tuned" by selecting the type
and
dimensioning of the valve system and selecting the filling medium.
Variants of the valve's design will determine to what extent the filling
medium is
permitted to flow between the respective chambers, adapted in all degrees from
open
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ducts providing a soft dampening and energy-absorptive effect to each chamber
being a
closed container after filling (Figure 6).
The possibility is also provided for that the duct is not in the form of a
through-
running tube, but are isolated "valve segments" placed in the flat hollow
spaces. A common
feature of this solution is that the valve tube and fender form an integral
unit in the flat,
compact areas irrespective of which type of valve system is used.
