Note: Descriptions are shown in the official language in which they were submitted.
CA 02284980 1999-09-27
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JOINTS FOR MODULAR SUPPORT STRUCTURES
This invention relates to a joint for use with modular support structures in
particular
tent frames and scaffolding.
It is known to use a plurality of supports of different sizes, i.e. of
different cross-
sections, such as tent or scaffolding poles, in conjunction with a plurality
of joints of
corresponding sizes to construct a modular support structure.
1 o The size of the modular support structure to be constructed determines the
cross-
section of the supports required. For larger structures, such as marquees,
large
diameter poles are required to withstand the large compression and bending
forces
experienced in the vertical supports whilst smaller diameter poles can be used
in other
areas, such as horizontal supports, where there are lower compression and
bending
~ 5 forces, to. minimise weight. Where the structure is smaller, for instance
a small tent,
the supports used will also be smaller due to the lower weight, and therefore
lower
compression and bending farces, the structure is required to support but may
still be of
differing diameters to save weight. The use of different size poles in a
single structure
requires the use of a large number of different joints. Moreover these joints
are often
?o designed specifically for a particular structure.
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As the complexity of the structure increases so does the number of different
joints and
therefore the difficulty of assembly of the structure, particularly in adverse
climatic
conditions or in the dark.
As a result of the need for a large variety of joints for each structure and
because
differently sized structures require a different variety of joints there is a
need to carry a
large number of different spare parts where a number of different structures
are
required. This not only increases production costs but also increases spares
costs and
stocks required.
to
According to the present invention there is provided a joint for a modular
support
structure comprising a plurality of connector arms characterised in that at
least one
connector arm is provided with a plurality of different sized mating surfaces,
so as to ,.
enable the connector arm to mate with any one support selected from a group of
~ 5 different sized supports.
The existence of the different sized mating ~~irfaces on the connector arm
means one
connector arm can mate with a large number of different supports and as such
fewer
different joints are needed, despite the use of supports of different sizes,
to form a
?o modular support structure. This can lead to reduced manufacturing costs and
gives
much improved commonality of parts for structures of different sizes and means
that a
kit for a specific structure can be assembled from a store of a few different
joints and
number of standard supports. Thus where a number of different structures are
required
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fewer spare parts are required overall. Also the complexity of assembling the
structure
is reduced.
In practice it is usual for supports to be of a substantially circular cross-
section as such
the connector can be arranged so that at least one of the connector arm mating
surfaces is of substantially circular cross-section. This allows existing
supports to
mate with joints according to the present invention and also allows for ease
of
manufacture.
A plurality of differently sized mating surfaces can be formed on the at least
one
connector arm co-axially or in an eccentric arrangement. Particularly
preferred is the
co-axial arrangement which allows for ease of manufacture and a consistency of
jointing direction.
The at least one connector arm may be arranged so as to be able to mate with a
surface on each of the variety of supports to be used with the joint. The
mating can be
achieved by any suitable means such as the use of a 'male connector arm' or a
'female connector arm' or a connector arm which can act as both a 'male' or a
'female' connector arse.
In use as a 'male connector arm' the at least one connector arm can be
configured so
as to have a plurality of differently sized mating surfaces arranged co-
axially ar in an
eccentric arrangement on the connector arm. Such a configuration allows the
inside
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surface of a support to mate with a corresponding surface on the outside of
the
connector arm.
In use as a 'female connector arm' the at least one connector arm can be
configured so
as to be hollow. In such a configuration a mating surface, or a plurality of
differently
sized mating surfaces arranged co-axially or in an eccentric arrangement, can
be
located on the inside of the connector arm. Such a configuration allows the
outside
surface of a support to mate with a corresponding surface on the inside of the
connector arm.
l0
In use as a 'male or a female connector arm' the at least one connector arm
can be
configured so as to have at least one mating surface on the outside of the
connector
arm and also to be hollow so as to provide at least one mating surface on the
inside of
the connector arm. Such a configuration allows a support to mate either with a
mating
~ s surface on the outside or inside of the connector arm. This configuration
therefore
allows for a larger number of differently sized mating surfaces to be arranged
on a
single ~~nnector arm than when the connector arm is configured solel~: as a
'male'
connector arm or a 'female' connector arm.
20 In order to increase the friction between the mating surface on the
connector arm and
the mating surface on the support whilst they are in contact with each other,
and
therefore the strength of the joint, a mating ring of suitable material such
as rubber can
be provided on or abutting either of the mating surfaces. Alternatively mating
rings
CA 02284980 1999-09-27
WO 98/45557 PCT/GB98/00703
can be provided on or abutting both the connector arm and the support mating
surfaces. The or each mating ring should be of suitable dimensions so as to
project
slightly above the mating surface which it is on or abuts whilst still
allowing the
mating surfaces to mate. Advantageously the or each mating ring could be
located in a
groove formed in either or both of the mating surfaces. The mating ring could
be
adapted so that a connector arm or a support only requires a single mating
ring to be
used covering all mating surfaces or individual mating rings could be used for
each
mating surface.
1o Advantageously a joint according to the present invention can be arranged
so as to
have bores in or around the hub of the joint. The bores can be used both to
reduce the
overall weight of the joint and also to provide points at which items can be
connected
to or suspended from the joint.
Usefully the present invention can result in there being a requirement for
only two
different configurations of joint in a typical kit; a 'T' shaped joint having
three
connector arms with their longitudinal axis in the same plane, which allows
connections at right angles to each other, and a '+' shaped joint having four
connector
arms three of which have their longitudinal axis in the same plane with the
fourth
2o connector arm having its longitudinal axis at an angle to this plane. The
'+' shaped
arrangement allows one of the supports to be mounted at an angle other than
90° to
the other supports forming, for example, a pitched roof for a tent.
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As a result of the use of joints according to the present invention, a single
kit need
only contain a plurality of the 'T' and '+' shaped joints and a plurality of
supports of
different dimensions to assemble a variety of different support strucY°
~s. By way of
example only a kit containing the following components can produ~three
different
tent structures; a large structure S.Sm x 7.3m; a medium structure 3.7m x 3.7m
or a
small structure 2.7m x 2.7m:
i/ 10 'T' shaped joints sized to receive 30mm and SOmm diameter poles
ii/ 25 '+' shaped joints sized to receive 30mm and SOmm diameter poles
to iii/ 12 poles 30mm in diameter and 800mm in length
iv/ 10 poles SOmm in diameter and 1100mm in length
v/ 20 poles 30mm in diameter and 1100mm in length
vi/ 20 poles SOmm in diameter and 1700mm in length
vii/ 28 poles 30mm in diameter and 1700mm in length
An embodiment of the invention will now be described, by way of example only,
with
reference to the drawings, in which:
Figure 1 is a plan view of a joint in accordance with the invention;
Figure 2 is a side elevation view of the joint shown in figure l;
Figure 3 is a side elevation view, at 90° to the elevation shown in
figure 2, of the joint
shown in figure 1;
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Figure 4 is a cross-section of figure 3;
Figure 5 is a cross-section of figure 3 showing an alternative internal
embodiment.
A joint in accordance with the invention comprises a plurality of connector
arms, la to
1 d, each having a plurality of different sized mating surfaces, 2a and 2b, to
allow each
connector arm, 1 a to 1 d, to mate with any one support selected from a group
of
different sized supports, one of the different sized mating surfaces, 2a or
2b,
corresponding to one of the mating surfaces of one of the supports. Each
connector
arni, 1 a to 1 d, forms an integral portion of the joint which extends
outwardly from the
1o hub of the joint, 3. Figure 5 illustrates an alternative embodiment wherein
at least one
of the connector arms, la to ld, has three different sized mating surfaces, 4a
to 4c.
The joint shown in figure 1 incorporates a central bore, 5, and radial bores,
6a to 6d,
which allow the user to attach items to, or suspend items from, the joint,
such as inner
liners in tents. The joint also shows, near the outer lip of each of the
connector arms,
1 a to 1 d, a groove, 7a to 7d, formed about the diameter of the connector arm
which is
adapted to receive an 'O' mating ring of suitable material such as rubber.
This 'O'
ring, when fitted in the gr~we of the connector arm, acts to increase the
friction
between the mating surfaces of the connector arm and the support mating with
the
connector arm, thus increasing the strength of the joint.
