Abstract:
This application is directed to a linkage system which provides continuous rotation to two or more interconnected quadrilaterals. The basic element of the linkage system is a multi-level link which provides firstly, a non-rotatable connection between two sub-links lying, in separate parallel planes and secondly, a rotatable connection for a further link lying in another parallel plane between the planes of the sub-links. By various interconnections between link elements, the quadrilaterals the linkage system will form various geometric patterns as the linkage is rotated. As the quadrilaterals lie in different planes, they may be continuously rotated with respect to each other. The linkage system may be used as a toy, a novelty item and as an educational tool.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the filing date of Provisional Patent Application No. 60/111,001 filed Dec. 4, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention disclosed is a unique type of linkage that is comprised of a multiplicity of links lying on different levels. These links form a chain or a matrix of interconnected four-bar linkages. I have discovered a novel arrangement of connections that allow the links in such a linkage to rotate continuously relative to one another, rather than having rotational limits. 
     When driven, such a linkage moves smoothly and synchronously, the links moving past one another on different levels. The patterns formed by the links as they change their configuration are surprising and aesthetically pleasing. 
     Such linkages are useful as toys or novelty items. The linkages can function as interactive educational tools, using the changing geometric patterns to reveal mathematical relationships. Other uses may include vehicles for rough terrain, where the linkage forms a unique tread that can move over rough surfaces. 
     Different types of linkage systems are found in the structures described in my prior U.S. patents, including U.S. Pat. No. 4,942,700, issued Jul. 24, 1990, entitled Reversibly Expandable Doubly-Curved Truss Structure; U.S. Pat. No. 4,780,344, issued Oct. 25, 1988, entitled Reversibly Expandable Three-Dimensional Structure; U.S. Pat. No. 4,981,732, issued Jan. 1, 1991, entitled Reversibly Expandable Structures; U.S. Pat. No. 5,234,727, issued Aug. 10, 1993, entitled Curved Pleated Sheet Structure; and U.S. Pat. No. 5,024,031, issued Jun. 18, 1991, entitled Radial Expansion/Retraction Truss Structure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the invention, reference is made to the following drawings which are to be taken in conjunction with the detailed description to follow: 
     FIGS. 1-2 show a basic element of the invention, a multi-level link; 
     FIGS. 3-5 show a multi-level link assembled with another basic element, a planar link; 
     FIG. 6 shows a first embodiment of the invention, a linkage consisting of two parallel assemblies capable of continuous rotation; 
     FIG. 7 is a diagram of lines corresponding to the linkage; 
     FIGS. 8-12 show other positions of the linkage; 
     FIG. 13 is an exploded view of a second embodiment of the invention, a linkage having elements on five levels; 
     FIGS. 14-20 show other positions of the linkage of FIG. 13; 
     FIG. 21 shows an exploded view of a third embodiment of the invention having one link that spans the full thickness of the linkage; 
     FIG. 22 shows a side view of the linkage of FIG. 21; 
     FIGS. 23-26 show front views of the linkage of FIG. 21 in different positions; 
     FIGS. 27-29 show perspective views of the linkage in different positions; 
     FIG. 30 is an exploded view of a fourth embodiment of the invention having one link that spans the full thickness of the linkage; 
     FIG. 31 shows a side view of the linkage of FIG. 30; 
     FIGS. 32-35 show front views of the linkage of FIG. 30 in different positions; 
     FIGS. 36-38 show perspective views of the linkage of FIG. 30 in different positions; 
     FIGS. 39-40 are an exploded view of a fifth embodiment of the multi-level link of the present invention consisting of three sub-links lying on three levels; 
     FIG. 41 shows an exploded view of a fifth embodiment of the invention having one link that spans the full thickness of the linkage; 
     FIG. 42 is a side view of the linkage of FIG. 41; 
     FIGS. 43-45 are a front view of the linkage of FIG. 41 in different positions; and 
     FIGS. 46-48 are perspective views of the linkage of FIG. 41 in different positions. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Shown in FIG. 1 is an exploded view of a link  1  that is made up of two sub-links  2  and  3 . Sub-link  2  has a pivot  6  on one end, and a second pivot  5  on its other end. Attached to pivot  5  is an element  4  that provides means to make a rigid (non-rotatable) connection to sub-link  3 . Sub-link  3  has a pivot  7  on one end and a cavity  8  which engages with element  4 . In FIG. 2 sub-links  2  and  3  are shown rigidly attached together. It is seen that link  1  lies within two distinct planes and has a central pivot  5  that remains exposed between sub-links  2  and  3 . Link  1  and others of its general type are thus hereinafter referred to as multi-level links. Pivots  6  and  7  lie at the extremities of link  1  and are hereinafter referred to as terminal pivots. 
     FIG. 3 is an exploded view of link  1  with a second angulated link  10  lying between sub-links  2  and  3 . Link  10  has a central pivot  11  and two terminal pivots  12  and  13 . Link  10  may be pivotally attached to link  1  such that central pivot  11  is engaged with pivot  5 . Link  10  and others of its general type are hereinafter referred to as planar links. FIG. 4 shows multi-level  1  and planar link  10  pivotally attached together. Link  1  is shown as a shaded element for clarity in the drawing. FIG. 5 shows links  1  and  10  rotated to a different position. It is seen that link  10  is capable of being rotated in a continuous fashion relative to link  1 . 
     FIG. 6 shows a linkage  15  consisting of multi-level link  1 , planar link  10  and four other planar links  20 ,  30 ,  40  and  50 . Links  20  and  30  are attached to one terminal pivot each of links  1  and  10 , and are pivotally attached to each other, thereby forming a closed loop. Similarly links  40  and  50  are attached to one terminal pivot each of links  1  and  10 , and are pivotally attached to each other, also forming a closed loop. 
     FIG. 7 is a diagram of lines that connect pivots-centers of linkage  15  as shown in FIG.  6 . The diagram may be seen to consist of two parallelograms  16  and  17 . The parallelograms are seen to correspond to parallel four-bar linkages in the actual mechanism. FIGS. 8-11 show linkage  15  in various positions. It is seen that link  10  may be rotated a full 360 degrees relative to link  1  with no interference from attached links  20 ,  30 ,  40  and  50 . FIG. 12 is a diagram that corresponds to lines connecting the pivots of linkage  15  as shown in FIG.  11 . It is seen to consist of two quadrilaterals  18  and  19  which are parallelograms in this case. In fact, for all positions of linkage  15  similarly constructed diagrams consist of two quadrilaterals, with link  10  forming a side of each of the quadrilaterals and a vertex of each quadrilateral. The arms of link  10  have been illustrated as extending at an obtuse angle with respect to each other. It is to be understood that link  10  would function the same if the arms were disposed at acute or right angles. Simarlary, sub-links  2  and  3  of link  1  can also be disposed at other than right angles with respect to each other. 
     FIG. 13 is an exploded view of linkage which is comprised of three multi-level links,  110 ,  120  and  130  and three angulated planar links  140 ,  150 ,  160 . Each central pivot of each multi-level link passes through a pivot of planar link  150 , such that sub-links  112 ,  122  and  132  lie on one side of planar link  150  and sub-links  113 ,  123  and  133  lie on the other side of link  150 . Planar link  140  is pivotally attached to one terminal pivot each of multi-level level links  110 ,  120  and  130 . Likewise, planar link  160  is pivotally attached to one terminal pivot each of multi-level level links  110 ,  120  and  130 . 
     FIG. 14 shows linkage  100  in assembled form. Each central pivot of multi-level links  110 ,  120  and  130  passes through and has a pivotal connection with planar link  150 . Sub-links  112  and  113  are rigidly attached together to form multi-level link  110 . Similarly sub-links  122 ,  123  and sub-links  132 ,  133  form multi-level links  120  and  130  respectively. FIG. 15 shows linkage  100  in a different position where planar link  150  has been rotated relative to multi-level link  120 . FIG. 16 shows another rotational position of linkage  100 . FIG. 17 is a diagram that corresponds to the lines connecting the pivots of linkage  100  as shown in FIG.  15 . It is seen to consist of four quadrilaterals (parallelograms)  171 ,  172 ,  173  and  174 . Links  140 ,  150  and  160  form a side and vertex of adjacent quadrilaterals. FIGS. 18 and 19 show other positions of linkage  100 . Examining the five positions shown in FIGS. 14-19, it is seen that the rotation of planar link  150  relative to multi-level link  120  continues without interference through a complete  360  degree revolution. FIG. 20 is a diagram that corresponds to lines connecting the pivots of linkage  100  as shown in FIG.  19 . It is seen to consist of four parallelograms  181 ,  182 ,  183  and  184 . In fact, for all positions of linkage  100  similarly constructed diagrams are seen to consist of four parallelograms. 
     FIG. 21 is an exploded view of a linkage  200 , which consists of two planar links  210  and  211 , as well as two multi-level links  220  and  230 . Multi-level link  220  is comprised of two sub-links  221  and  222 , and lies on either side of planar link  210 ; multi-level link  230  is comprised of sub-links  231  and  232  and lies on either side on planar link  211 . Also shown is FIG. 21 is yoke-like link  260  which spans the full thickness of linkage  200  and is pivotally attached to links  220  and  230 . Link  260  is shown in two exploded parts for clarity in the drawings. Additionally, link  260  is pivotally attached to links  240  and  250  which serve to synchronize the motion of linkage  200 . Also shown are knobs  241 ,  251  which are used to drive the linkage. Knobs  241 ,  251  are connected to links  240 ,  250  by means of a multi-level link, which rotatably couples links  240 ,  250  to link  260  and rigidly couples links  240 ,  250  to links  241 ,  251 . As is shown in FIG. 22, yoke  260  may include a handle portion  261  having an opening  262  (or other means) for attachment to an external object such as a key ring. 
     FIG. 22 is a side view of linkage  200 . Link  260  spans the full width of linkage  200 . Hereinafter links of the same type as  260  shall be referred to as spanning links. FIG. 23 is a front view of linkage  200 . FIG. 24 is a front view of linkage  200  in a different position. FIG. 25 shows a diagram of lines that correspond to the pivots of linkage  200 . The diagram is seen to consist of three parallelograms  270 ,  271  and  272 . FIG. 25 shows a front view of linkage  200  in yet another position. FIGS. 27,  28  and  29  are perspective views of linkage  200  in three positions corresponding to the front views  23 ,  24  and  26  respectively. As can be seen in FIG. 21, certain link elements such as elements  240 ,  250  are V-shaped and have arms which are not linked to another element. Such arms add to the appearance of the overall device, but are not strictly needed for functionality. Similarly, each side of yoke element  260  is shown as X-shaped, but could also take various other configurations depending on aesthetic or functional requirements. 
     FIG. 30 shows an exploded view of a linkage  300  which consists of three planar links  340 ,  350  and  360 , as well as three multi-level links  310 ,  320  and  330 . Multi-level link  310  is comprised of two sub-links  311  and  312 , and lies on either side of planar link  340 ; multi-level link  320  is comprised of sub-links  321  and  322  and lies on either side on planar link  350 ; multi-level link  330  is comprised of sub-lines  331  and  332  and lies on either side on planar link  360 . Also shown in FIG. 30 is a Y-shaped yoke link  390  which spans the full thickness of linkage  300  and is pivotally attached to links  310  and  330 . Link  390  is shown in two exploded parts for clarity in the drawing. Link  390  is pivotally attached to links  370  and  380  which serve to synchronize the motion of linkage  300 . Additionally shown are gear elements  362 ,  363  which may be rigidly attached to links  370 ,  332  respectively. Also shown is a third gear  361 , which includes a knob  391  and which engages with gears  362 ,  363 . These three gears serve to assist in synchronizing the movement of linkage  300 . 
     FIG. 31 shows a side view of linkage  300 . Spanning link  390  is seen to span the full width of linkage  300 . FIG. 32 shows a front view of linkage  300 . FIG. 33 shows a front view of linkage  300  in a different position. FIG. 34 shows a diagram of lines that correspond to the pivots of linkage  300 . The diagram is seen to consist of four parallelograms  391 ,  392 ,  393  and  394 . FIG. 35 shows a front view of linkage  300  in yet another position. FIGS. 36,  37  and  38  show perspective views of linkage  300  in three positions corresponding to the front views  32 ,  33  and  35  respectively. The pawl shaped extensions  392 ,  393  of links such as  330 ,  370  serve to provide clearance for other link elements during rotation. 
     FIG. 39 is an exploded view of a link  420  which is comprised of three sub-links  421 ,  422  and  423 . Sub-link  421  has a pivot  424  to which an element  425  is attached, element  425  provides means to make a rigid connection to sub-link  422 . Likewise, sub-link  422  has a pivot  426  to which an element  427  is attached, element  427  providing means to make a rigid connection to sub-link  423 . FIG. 40 shows link  420  in its assembled condition. Link  420  is a multi-level link having three distinct levels. FIG. 41 shows an exploded view of linkage  400 . It consists of two Y-shaped planar links  440  and  450 , as well as three multi-level links  410 ,  420  and  430 . Multi-level link  410  is comprised of three sub-links  411 ,  412  and  413 . Planar link  440  lies between sub-links  411  and  412 . Planar link  450  lies between sub-links  412  and  413 . In a similar manner multi-level links  420  and  430 , comprised of sub-links  421 ,  422 ,  423  and  431 ,  432 ,  433  respectively, lie on either side of planar links  440  and  450 . Also shown in FIG. 41 is a Y-shaped yoke link  460  which spans the full thickness of linkage  400  and is pivotally attached to links  410 ,  420  and  430 . 
     FIG. 42 shows a side view of linkage  400 . Spanning link  460  may be seen to span the full width of linkage  400 . FIG. 43 shows a front view of linkage  400 . FIG. 44 shows a front view of linkage  400  in a different position. FIG. 45 shows a front view of linkage  400  in yet another position. FIGS. 46,  47  and  48  are perspective views of linkage  400  in three positions corresponding to front views  43 ,  44  and  45  respectively. 
     The present invention has been described with respect to preferred embodiments. It is to be understood that modifications and variations to the illustrated structures may be resorted to, by persons skilled in the art, without departing from the scope of the invention, as set forth in the claims to follow.