Dome hubs for geodesic construction
[451 Apr. 15, 1975 1 DOME HUBS FOR GEODESIC CONSTRUCTION [75] Inventor: Rae Goldwin Jury, Vancouver,  
 British Columbia, Canada [73] Assignee: Arthur Bell, Prince George, British Columbia, Canada; a part interest [22] Filed: Aug. 2, 1973 [2]] Appl. No.: 385,120  
 [30] Foreign Application Priority Data May 18, 1973 Canada 171788 [52] US. Cl. 403/174; 403/176; 403/339; 403/344; 52/81; 52/DIG. 1O  
 [51] Int. Cl E04b 7/06; Fl6b 1/00 [58] Field of Search 403/64, 164, 169, 170,  
 403/171, 172, 174, 176, 274, 279, 282, 292, 339, 342, 344, 350, 374, 383, 393, 396, 405; 52/80-82, DIG. 10; 135/3 B [56] References Cited UNITED STATES PATENTS 3,148,539 9/1964 Cook 52/DIG. 10 3,181,542 5/1965 Bareis 403/64 X 3,798,586 3/1974 Huska 285/322 X FOREIGN PATENTS OR APPLICATIONS 1,395,048 3/1965 France 403/170 370,537 3/1923 Germany 678,293 9/1953 United Kingdom 403/64 Primary Examinerwerner H. Schroeder Attorney, Agent, or Firm-Ladas, Parry, Von Gohr, Goldsmith &amp; Deschamps [57] ABSTRACT Goedesic structures generally comprise a plurality of members arranged to form polygon spaces and joined together by dome hubs. The overall structure commonly takes the form of a hemisphere. Prior dome hubs for small portable structures have been found too weak when the structure is subjected to high winds or when snow accumulates unevenly or when the snow on one side thaws and slides off. The weakness has been found due to individual members suffering tensile stresses and withdrawing from dome hub sockets. The present invention provides lightweight easily assembled dome hubs which lock the structural members against inadvertent withdrawal.  
 9 Claims, 1 Drawing Figure l DOME HUBS FOR GEODESIC CONSTRUCTION This invention relates to means for joining together the elements of a generally portable geodesic structure of the type where the structural elements generally define triangular-shaped spaces.  
  The subject matter of this application is an improvement upon the devices disclosed and claimed in Canadian application 152.337 filed Sept.22, 1972 and US. application Ser. No. 353.437 filed Apr. 23, 1973. the inventor of these applications being John J. Chato and both applications being assigned to Rae Goldwin Jury, the applicant of this application. j j  
  The aforementioned Chato application disclosed a joining means for geodesic structures, which were identified as dome hubs&#34; and the dome hubs described have been found to be excellent when used on small geodesic domes, which, when subsequently covered with sheets of plastics materials, canvas, fabric and the like. form satisfactory small buildings.  
  It has been discovered, however, that uneven loading of a dome structure, for example snow or wind pressures on one side thereof. can develop tensile stresses in individual elements of the structure.  
  In some forms of the Chato structure no positive means were disclosed for preventing the strut elements from withdrawing from the domehub. All the embodiments in the Chato application provided for clamping the struts within a substantially U-shaped socket by urging the side limbs of the U-shape together by means of nuts and bolts. In yet another embodiment the inner surfaces of the U-shaped socket were roughened-up to enhance friction between the strut and the associated socket.  
  The present inventiion provides a dome hub which is suitable for much larger structures than evisaged by the Chato dome hub and the dome hub according to the present invention provides positive means to accommodate tensile loads in the struts.  
  Thus, the present invention is suitable not only for larger structures but for structures having uneven loading due to snow or wind on one side of the structure.  
  A preferred embodiment of the invention will be now described with reference to the accompanying drawing.  
  A dome hub joint indicated at l is seen to comprise a central spider having a polygonal centre portion and a plurality of partial-tubular arms 12 integrally formed with the centre portion 10. A transverse bar 14 is disposed on the inner surface of each arm 12 intermediate the length thereof and the outer surfaces of arms 12 have thread or serrated formations l6 thereon. The arms 12 receive the ends of geodesic members each of which has a notch 22 which cooperates with the bar 14. The hub arms 12 may be round or polygonal in cross section to accommodate geodesic members 20 of similar cross sectional shape.  
  The geodesic members 20 are retained in the arms 12 by lock nuts 30 having an internal thread or serrations matching the threads or serrations 16 on the arms 12.  
  It will be appreciated that the above disclosed dome hub is ideally suited for manufacture by injection moulding from a suitable plastics material. It is to be understood, however, that the central spider 1 and/or the nuts 30 can be made of metal.  
  While in the single drawing appended hereto the central spider 1 places all of the structural members in a common plane, it will be appreciated that the arms may be set at slight angles to such a common plane in order to accommodate overall curvature inherent in dome structures, particularly of the smaller sizes.  
  It is to be further understood that the interior surface of the arms 12 may be slightly tapered, with the larger dimensions adjacent the extremity of the arms, and the ends of the geodesic members correspondingly tapered to ensure a more snug fit. Similarly, the exterior of the arms 12 may be slightly tapered so that the interior dimensions of the arms 12 are reduced by deformation when the nuts are tightened so as to ensure a more rigid assembly. Again, the internal dimensions of the nuts 30 and the associated threads or serrations on the interior. surfaces thereof may be slightly tapered so as to produce similar deformation of the arms 12 to enhance the rigidity.  
  Other embodiments falling within the terms of the appended claims will appear to those skilled in the art.  
  The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: I  
  1. An improved dome joint structure for use with a building dome of the type having a large number of similar geodesic members, said joint structure including a central spider having a polygonal central portion and a plurality of radiating arms integrally formed with the central portion for receiving and holding the ends of geodesic members, in&#39;which the improvement comprises a. each of said arms is of partial tubular configuration and has thread of serrated formations on the exterior surface thereof;  
 b. the interior dimensions of each said arms is substantially equal to the external dimension of the end of a geodesic members;  
 . a nut is provided for each arm having thread or serrated formations on the interior surface thereof, matching the formations on the exterior surface of the arm, said nut when rotated after insertion of the end of a geodesic member into the arm serving to deform the partial tubular configuration of the arm inwardly against the end of the geodesic member to hold the same. 2. A dome joint structure as in claim 1 wherein each &#39;of said arms is provided with a transverse bar or ridge disposed on the interior surface and intermediate the length thereof to be engaged with an associated notch adjacent the ends thereof of the geodesic members to be received within said arms.  
  3. A dome joint structure as in claim 1 wherein the interior surfaces of said&#39;arms are tapered to receive correspondingly tapered ends of geodesic members to be received therein.  
  4. A dome joint structure as in claim 1 wherein the exterior surfaces and the thread or serrated formations thereon of said arms are tapered so as to be deformed inwardly against the ends of geodesic members received therein to enhance the rigidity of the assembly.  
  5. A dome joint structure as in claim 1 wherein the exterior surfaces and the thread or serrated formations thereon of said arms and the interior surfaces of said nuts are tapered so the said arms are deformed inwardly against the ends of the geodesic members received therein to enhance the rigidity of the assembly.  
  6. A dome joint structure as in claim 1 wherein all of said arms lie in a substantially common plane.  
  7.&#39;A dome join! structrue asin claim 6 wherein all of central spider is formed of a plastics materiaL said arms are slightly angulated away from said com- 9. A dome joint structure as in claim 1 wherein said mon plane. nuts are formed of a plastics material.  
 8. A dome joint structure as in claim 1 wherein said