Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates, generally, to space frame structures and,
more specifically, to a node construction for use in a space frame.
BACKGROUN~ OF THE INVlENTION
Space frames are well known in the art and are used in many applications.
They are relatively light, three dimensional structures capable of covering large
areas with a minimum of support columns and, therefore, are ideally suited ~or
athletic arenas and exhibition halls. They may also be ~lsed in floating marine
docks and other such structures in which buoyancy cells may be placed in the
spaces between the frame members to permit the structure to float. Space frame
are generally characterized as three-dimensional, tetrahedral structures compr;sed
of a plurality of frame members interconnected in end-to-end relation by node
rnembers in predetermined directions to form a wide range of three dimensional
shapes with good distribution of all stresses throughout the structure.
The frame members are usually metal or plastic tubes. The node members
are often hollow or solid spherical bod;es made of metal or plastic. There is a
large variety of methods of and connectors for connecting the ends of the frame
members to the node members. The most common method of joining the frame
members to the node members is to use a threaded connector which is threaded
into the node member and axially into the end of frame member. The following
patents are representative of connector arrangements based on this connection
principle: CHICC~IIS et al United States Patent No. 3,789,562 granted on
February 5, 1974, MILLER United States Patent No. 3,914,060 granted on
October 21, 1975, JACHMANN United States Patent No. 3,980,408 granted on
September 14, 1976, ENDZWE~IG United States Patent No. 3,982,841 granted on
September 28, 1976, CILVET United States Patent No. 4,027,449 granted on
June 7, 1977, FELIX United States Patent No. 4,8()6,041 granted on February 21,
1989 and CROUC~IER et al United States Patent No. 4,863,303 granted on
September 5, 1989. While this form of connection is relatively simple and
inexpensive, it suffers from the drawback that it is often awkward, if not difficult,
to remove and replace a single frame member without disturbing other struchlral
members. Other connecting methods are relatively complex and expensive, have
many parts and require specialized tools.
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SUl\IMARY OF THE INVENTION
The present invention seeks to provide a simple and inexpensive
arrangement for connecting space frame frame members to node members so as
to permit easy withdrawal and installation of frame members without disturbing
5 other structural members.
To facilitate in-situ replacement of a frame member, the present invention
provides a connection arrangement which permits the frame member to be moved
radially with respect to its own axis into and out of engagement of its ends with
associated node connecters. When engaged with its connectors, the frame
10 member may then be moved between locked and unlocked positions by angular
displacement of the frame member with respect to its associated connectors.
This is achieved by providing a frame member with tubular end portions
which define an axial bore and a slot which extends axially inwardly from the end
of the frame member and opens into the bore and which has a width which is less
15 than the diameter of the bore. Each of the connectors is in the form of a post
adapted to be received in an associated bore and cooperate therewith to keep theframe member and connector in coaxial alignment with one another. The cross
sectional width of the post is narrower than the width of the slot to permit theconnector to pass edgewise through the slot into and or out of the bore. The
20 cross sectional length of the post is larger than the width of the slot so that when
the post is oriented perpendicular to the slot, it is retained or locked within the
frame member.
Thus, one aspect of the present invention is generally defined as a node for
a space frame having a plurality of nodes interconnected by a plurality of frame25 members extending between and secured to the nodes, each frame member
having tubular end portions defining an axial bore, and a slot in the tubular end
portions extending longiiudinally from the end of the frame member, opening intoand being narrower than the bore. The node comprises a node body having a
plurality of connectors extending radially olltwardly therefrom for coaxial
30 reception within one of the bores of an associated frame member, each connector
having an elongated connector body having a cross sectional width which is
smaller than the width of the slot so as to enable the connector to pass throughthe slot when disposed in edgewise alignment therewith and a cross sectional
length which is greater than the width of the slot and less than the diameter of the
35 bore so as to prevent the connector from passing through the slot when disposed
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in other than edgewise alignment while permitting the connector to be rotatably
received in the bore.
BRIEF DESCRlPTION OF THE DR~WI~GS
These and other features of the invention will become more apparent from
the following description in which reference is made to the appended drawings
wherein:
FIGlJPcE 1 is a perspective view of a marine dock application of a space frame;
FIGURE 2 is a partially broken, perspective view of a preferred embodiment of
the present invention;
FIGURES 3 and 4 are cross sectional and top views, respectively, of a node
member according to a preferred embodiment of the present invention;
FIGURE~ , 7 and 8 are isometric, cross sectional and end views of a
connector according to a preferred embodiment of the present invention;
FIGURES 9, 10, and 11 are isometric, cross sectional and edge views of a
connector holder according to a preferred embodiment of the present
invention;
FIGURE 12 is a partially broken, cross sectional view of a frame member
operatively connected to a node member according to a preferred
embodiment of the present invention; and
FIGUl~ES 13a, 13b and 13c are views illustrating the manner in which a frame
member is installed on and withdrawn from the connector.
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D~:SCRIPTION OF PREFERRED EMBODIMENT
FIGURE 1 illustrates a space frame 10 used in a marine dock application.
The space frame includes a plurality of frame members 12 whose ends 14 and 16
are removably secured to node members 18. Buoyancy cells 19 may be positioned
5 in the tetrahedral spaces between the frame members to provide floatation and
suitable decking material may be secured to ~lpper node members in any suitable
fashion so as to provide a deck 20.
FIGURE 2 is an exploded perspective view of a preferred embodiment of
the present invention for connecting a frame member lL2 to a node member 18.
10 According to this embodiment, the ~rame member is formed with a cy]indrical
bore 22 which extends axially inwardly from the free end of the frame member
and a slot 24 which also extends axially inwardly from the free end of the framemember and which communicates with the bore as shown. Bore 22 may extend
along the entire length of the frame member and, therefore, may be the inner
15 diameter of a commercially availab~e cylindrical tube. The slot has longitudinally
extending, parallel side edges 26, the spacing of which is less than the diameter
of the bore for reasons which will become clear below.
A connector 30 is adapted to be coaxially positioned within bore 22 and
secured to end 14 of the frame member. The connector is unitary and includes
20 a generally cylindrical shank portion 32 and a cylindrical head portion 34 of larger
diameter than the shank portion. The diameter of the shank portion is only
slightly less thcm the inner diameter of bore 22 to ensure a tight coaxial fit of the
two members but sufficiently less to allow the frame member to be rotated about
the connector without undue difficulty. The shank is formed with a pair of
25 opposed, longitudinally extending planar faces or surfaces 36 which define a pair
of opposed, longitudinally extending arcuate faces 3~.
To permit the connector to pass edgewise through the slot, the diametrical
spacing of planar faces 36 is less than the width of slot 24 and the length of the
shank is slightly less than the length of the slot 24. The diameter of arcuate faces
30 38 is greater than the width of the slot to prevent the connector from passing
sideways through the slot once it has been operatively positioned with the bore
22. This may best be understood by referring to FIC:U~ES 13a, 13b and 13c. In
order to install a frame mernber, side edges 26 are aligned with planar faces 36of the connector as shown in FIGUR~: 13a. The frame member is then moved
35 radially with respect to its own axis so that the connector passes entirely through
"
the slot to the unlocked position shown ;n FIGURE 13b. In this position, one of
the inner faces 38 of the connector is proximate the inner wall of the bore. Theframe member is then rotated through 90 about its axis to the locked position
shown in FI~URE 13c, which is the operative position of the two members. The
5 two members are securecl in this position by a bolt 40, shown in phcmtom lines,
which passes through diametrically aligned opposed holes 42 in the frame member
and a hole 44 in the connector. As can be seen, the axis of bolt hole 44 is parallel
to planar faces 3~ of the connector. It will be understood that any other suitable
means may be used to secure the frame member to the connector.
With particular reference to FIGUl~S 2 and 5-8, the free end of the shank
is also formed w;th six radial slots 46. These slots may be used in conjunction
with a suitable screwdriver tip (not shown) to align the planar faces of the
connector with the edges of the slot. As indicated below, in the preferred
embodiment of the invention, the connectors are freely rotatably mounted in the
node member.
With reference to ~IGURE~ 2, 3 and 4, it will be seen that the node
members are hollow, substantially spherical bodies 50 having a plurality of equally
angularly spaced stepped bores 52 to receive the head portion of a connector anda connector holder. Each bore S~ comprises a concentric, internally threaded
bore 56 and a b]ind bore 54 and which defines an annular shoulder 58. The
diameter of blind bore 54 is slightly greater than the diameter of the head portion
34 of the connector while the depth of the bore 54 from shoulder 58 to the base
60 of the bore is slightly greater than the thickness of the head 34.
As shown in FIGU~ES 2, 9, 10 and 11, the connector holder 70 is in the
form of an annular disk 72 having a threaded outer edge 74, an inner bore 76 andopposed, upper and lower annular faces 78 and 80. Thus, to secure a connector
to a node member, the head of the connector is seated on base 60 coaxially within
bore 54. The end of the shank is inserted into hole 76 of the holder and the
holder is threaded into bore S6 until lower face 80 engages shoulder S8 in slightly
spaced relation to the underside 35 of the head 34. The holder may be securely
tightened by inserting a suitable tool into blind holes 84 formed in upper face 78
of the holder and applying an appropriate torque thereto. As mentioned earlier,
there is sufficient axial and radial clearance within the bore 54 to enable the
connector to rotate about its own axis. Such rotation is desirable to avoid the
need for high precision in the positioning of the connectors in the node members
,
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and al;gnment of the aforementioned slots in the encls of the frame members.
Thus, when installing a frame member, the planar faces of the connector may be
brought into alignment with the edges of the slot of a frame member simply by
angularly adjusting the connector by hand.
It will be seen from the forgoing that the present invention allows the
frame members to be rotated about their respective axes within an assembled and
functional space frame without sacrificing the structural integrity of the spaceframe. This facilitates removal and replacement of damaged frame members
while the structure is intact.
It will be understood that various modifications and alterations may be
mcade to the preferred embodiment described hereinabove without departing from
the spirit of the invention as defined in the appended claims. For example, it will
be mderstood that the connector may be secured to the node members by means
other than the stepped bore and connector holder described above. One end of
the connectors may be secured directly to the nodes by screw threads, glue or
suitable solvent.
