U.S. patent number 3,672,104 [Application Number 05/100,912] was granted by the patent office on 1972-06-27 for nesting three dimensional lazy tong structure.
This patent grant is currently assigned to TRW Inc.. Invention is credited to George R. Luckey.
United States Patent |
3,672,104 |
Luckey |
June 27, 1972 |
NESTING THREE DIMENSIONAL LAZY TONG STRUCTURE
Abstract
A nesting three-dimensional lazy tong structure of hollow
polygonal cross-section having tapered sides provided by lazy tong
frames whose hinged links are pivotally joined and cross-over one
another in a manner such that the successive link sets or tiers of
the structure nest one within the other when the structure is
retracted to its contracted configuration to provide the structure
with a contracted length approximating the contracted dimension of
a single link set or tier. A lazy tong frame and link pair for the
structure.
Inventors: |
Luckey; George R. (Playa Del
Rey, CA) |
Assignee: |
TRW Inc. (Redondo Beach,
CA)
|
Family
ID: |
22282169 |
Appl.
No.: |
05/100,912 |
Filed: |
December 23, 1970 |
Current U.S.
Class: |
52/109;
248/277.1; 52/646; 182/141 |
Current CPC
Class: |
B66F
3/22 (20130101); E04H 12/187 (20130101) |
Current International
Class: |
E04H
12/00 (20060101); E04H 12/18 (20060101); B66F
3/00 (20060101); B66F 3/22 (20060101); E04h
012/10 () |
Field of
Search: |
;52/109,645,108,646
;14/45 ;74/521 ;182/69,141 ;187/18 ;248/277 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Braun; Leslie A.
Claims
What is claimed as new in support of Letters Patent is:
1. A link pair for a lazy tong frame comprising:
a pair of similar links having mutually parallel central portions
arranged side by side at opposite sides of an intervening plane
passing between and parallel to said link portions;
a center pivot joining said central link portions on a center pivot
axis normal to said intervening plane;
each link having relatively short and long arms at opposite sides
of said pivot;
said short arm of one link and said long arm of the other link
extending across said intervening plane, whereby said latter arms
crossover one another;
said short link arms having end portions in a common plane parallel
to and located at one side of said intervening plane, and said long
link arms having end portions in a common plane parallel to and
located at the opposite side of said intervening plane;
said short arm end portions having end pivot means with pivot axes
parallel to and equally spaced from said center pivot, and said
long arm end portions having end pivot means with pivot axes
parallel to and equally spaced from said center pivot, the pivot
axes of each link being located in a common longitudinal plane of
the respective link; and
said links being rotatable about said center pivot to folded
positions wherein said pivot axes are located in a common
longitudinal plane of said links.
2. A link pair according to claim 1 wherein:
said crossing link arms have surfaces which abut in said folded
positions.
3. A link pair according to claim 2 wherein:
said surfaces comprise edge surfaces of said links located in said
common planes containing the pivot axes of the respective
links.
4. A lazy tong frame comprising:
a number of link pairs each including a pair of similar links
having mutually parallel central portions arranged side by side at
opposite sides of an intervening plane passing between and parallel
to said link portions;
a center pivot joining said central link portions on a center pivot
axis normal to said intervening plane;
each link having relatively short and long arms at opposite sides
of its center pivot, and said short arm of one link and said long
arm of the other link extending across said intervening plane,
whereby said latter arms crossover one another;
said short link arms having end portions in a common plane parallel
to and located at one side of said intervening plane, and said long
link arms having end portions in a common plane parallel to and
located at the opposite side of said intervening plane;
said link pairs being arranged end to end in lazy tong fashion with
their center pivot axes parallel to one another and located in a
common plane and with said short arm end portions of each link pair
located opposite said long arm end portions of the adjacent link
pair;
end pivots joining the adjacent link end portions of adjacent link
pairs on end pivot axes parallel to said center pivot axes;
the corresponding end pivots of each link pair being equally spaced
from the center pivot of the respective link pair, and the pivot
axes of each link being located in a common longitudinal plane of
the respective link;
said links diminishing in length in the direction of one end of the
frame, whereby said frame is tapered and narrows in the direction
of said one end, and the pivotally joined link arms of adjacent
link pairs have equal length; and
said frame is retractable to a contracted configuration wherein
said pivot axes of all said link pairs are located in a common
plane.
5. A lazy tong frame according to claim 4 wherein:
said crossing link arms have surfaces which abut in said folded
positions.
6. A lazy tong frame according to claim 5 wherein:
said surfaces comprise edge surfaces of said links located in said
common planes containing the pivot axes of the respective
links.
7. A nesting three-dimensional lazy tong structure of hollow
polygonal cross-section, comprising:
a number of lazy tong frame forming the sides, respectively, of
structure;
each frame comprising a number of link pairs each including a pair
of similar links having mutually parallel central portions arranged
side by side at opposite sides of an intervening plane passing
between and parallel to said link portions;
a center pivot joining said central link portions on a center pivot
axis normal to said intervening plane;
each link having relatively short and long arms at opposite sides
of its center pivot, and said short arm of one link and said long
arm of the other link extending across said intervening plane,
whereby said latter arms crossover one another;
said short link arms having end portions in a common plane parallel
to and located at one side of said intervening plane, and said long
link arms having end portions in a common plane parallel to and
located at the opposite side of said intervening plane;
said link pairs being arranged end to end in lazy tong fashion with
their center pivot axes parallel to one another and located in a
common plane and with said short arm end portions of each link pair
located opposite said long arm end portions of the adjacent link
pair;
end pivots joining the adjacent link end portions of adjacent link
pairs on end pivot axes parallel to said center pivot axes;
the corresponding end pivots of each link pair being equally spaced
from the center pivot of the respective link pair, and the pivot
axes of each link being located in a common longitudinal plane of
the respective link;
said links diminishing in length in the direction of one end of the
frame, whereby said frame is tapered and narrows in the direction
of said one end, and the pivotally joined link arms of adjacent
link pairs have equal length;
said frames being arranged edge to edge in a hollow polygonal
configuration with the narrow ends of said frames at the same end
of said structure;
rigid corner brackets joining the adjacent end pivots of adjacent
frames; and
said structure being retractable to a contracted configuration
wherein the tiers of said structure nest one within the other and
all the pivot axes of said structure are located in a common plane
normal to the longitudinal axis of said structure.
8. A structure according to claim 7 wherein:
said structure has a generally triangular cross-section and
includes three lazy tong frames.
9. A structure according to claim 7 wherein:
each said frame includes a pair of end links at each frame end
equal in length to the adjacent link arms, pivot means joining one
end of each pair of end links to the end portions of the adjacent
link arms on pivot axes parallel to the remaining frame pivot axes,
and pivot means joining the opposite ends of said end links on a
pivot axis parallel to the remaining frame pivot axes.
10. A structure according to claim 9 including:
mounting brackets and a support at the wide and narrow ends,
respectively, of said frames and pivotally joined to said opposite
ends of said end links by the adjacent end link pivots.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to extensible and contractable
structures and more particularly to a novel nesting
three-dimensional lazy tong structure. The invention relates also
to a lazy tong frame and hinged link pair for the structure.
2. Prior Art
Many applications exist and other applications continuously arise
for towers, booms and the like which can be retracted to a compact
stowage configuration and extended to a relative great height or
length for use. Numerous examples of such structures exist in the
prior art. Typical of such prior art structures, for example, are
those disclosed in U.S. Pat. Nos. 797,077; 1,947,647; 2,299,687;
and 3,053,351.
Of major importance in the design of such structures is their ratio
of extended to contracted length. In most, if not all applications,
this ratio should be as large as possible. That is to say, the
contracted length should be relatively small and the extended
length should be relatively large. As a general rule, the larger
this ratio, the smaller will be the weight of the structure per
unit deployed length. While weight may not be critical in many
applications, it is extremely important in others, such as space
applications.
Extensible structures of the class described vary widely in
construction. The present invention is concerned with deployable
structures of the general type disclosed in the earlier mentioned
prior art patents which employ, essentially, a three-dimensional
lazy tong construction consisting of hinged link sets pivotally
joined to one another. The prior art structures of this kind suffer
from the disadvantage that contraction of the structure is limited
by edge to edge abutment of the links of adjacent link sets or
tiers. As a consequence, the contracted length of the structure is
effectively the summation of the contracted dimensions, along the
deployment axis, of the several link tiers.
SUMMARY OF THE INVENTION
The present invention provides an improved extensible structure of
the class described which is uniquely constructed and arranged such
that the successive hinged link sets or tiers nest or telescope one
within the other when the structure is contracted. This nesting
feature provides the structure with an effective contracted length
approximating the contacted dimension, along the deployment axis,
of a single link set or tier.
Like certain of the prior art extensible structures, the present
extensible structure is essentially a three-dimensional lazy tong
structure of hollow polygonal cross-section. The sides of the
structure are furnished by similar lazy tong frames pivotally
joined to one another along the longitudinal corners of the
structure by corner brackets. The several frames define successive
sets or tiers of hinged links, each including one pair of hinged
links in each of the frames and corner brackets pivotally joining
the corresponding link ends of the link pairs; that is to say each
tier of the structure comprises the corresponding hinged link pairs
in the several lazy tong frames and their respective corner
brackets of the structure. Each link pair is composed of two links
of equal length having center and end pivots and pivotally joined
to one another at their center pivots. The center and end pivots of
each link are located in a common longitudinal plane of the
link.
According to the present invention, the links of the successive
link pairs of each link frame, and hence the links of the
successive link set or tiers of the structure, diminish in length
toward one end of the structure, such that each frame tapers toward
the latter end and the structure has a generally pyramidal
configuration. Also the two hinged links of each link pair are
longitudinally offset so that each link has a long end at one side
of the center link pivot and a short end at the opposite side of
this pivot. The corresponding ends of the two links are located at
opposite sides of the center pivot. The two links of each link pair
are shaped such that the short end of one link crosses over the
long end of the other link, and the links are rotatable on their
center pivot axis to a folded or contracted configuration wherein
the axis of the several link pivots are located in a common
longitudinal plane of the links. In this folded configuration, the
short ends of the two links are located at one side, hereafter
referred to as the inner side, of a plane passing between the links
at and normal to their center pivot and the long ends are located
at the opposite side, hereafter referred to as the outer side, of
the plane. Also, the end pivots on the short ends are located
longitudinally inward of, i.e. closer to the center pivot that, the
end pivots on the long ends. The corresponding end pivots are
equally spaced from the center pivot.
In the overall deployable structure, the short ends of the links of
each link pair of each lazy tong frame are pivotally joined to the
outer sides of the long links of the adjacent link pair, in the
direction of the small ends of the frame and structure, at the end
pivots of the respective link ends. The adjacent corresponding
pivotally joined link ends of the several link frames are pivotally
joined by corner brackets to form the link sets or tiers of the
structure.
The present structure is so arranged that when it contracts, the
tiers of the structure nest one within the other in a manner such
that the fully contracted structure has a length approximating the
overall width dimension of a single tier in its contracted or
folded configuration. Accordingly, the structure is characterized
by a high ratio of extended length to contracted length.
According to another feature of the invention, each lazy tong frame
has planar end links which are pivotally joined at their outer ends
to the ends of the adjacent link pair and at their inner ends to
one another. The pivotally joined inner ends of the planar end
links at the large end of the structure are pivotally attached to a
supporting base. A platform or other support for an object to be
deployed with the structure is pivotally attached to the pivotally
inner joined ends of the planar end links at the small end of the
structure. The structure is thus retractable to stowed
configuration against the base and is extendable outwardly from the
base to deployed configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings: structure
FIG. 1 is a side elevation of a present lazy tong structure in its
extended configuration;
FIG. 2 is a plane view of the sturucture in its contracted
configuration;
FIG. 3 is a side elevation of the contracted structure;
FIG. 4 is a section taken on line 4--4 in FIG. 2;
FIG. 5 is an enlarged perspective view of one link pair of the
structure;
FIG. 6 is a top plan view of one hinged link pair.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The drawings illustrate a nesting three-dimensional lazy tong
structure 10 according to the invention. The particular structure
shown is a three-sided pyramidal structure of generally triangular
cross-section. However, it will become evident as the description
proceeds that the structure may have four or more sides.
The sides of the structure 10 are provided by similar lazy tong
frames 12. Each frame 12 includes a number of hinged link pairs 14
which are pivotally connected in the manner shown and described
below to form a lazy tongs. Each link pair is composed of a pair of
centrally hinged links 16, 18 of equal length. The links of
successive link pairs in the direction of one end of the structure
diminish in length such that each frame 12 is longitudinally
tapered, and the structure, when extended, has a generally
pyramidal configuration. Except for these differing lengths of
their links, the link pairs are identical. Accordingly, a
description of one link pair will suffice for all. With this in
mind, a link pair 14 will be described by reference to FIG. 5.
The two links 16, 18 of link pair 14 are fashioned from two similar
relatively stiff, though resiliently flexible, straps or bars which
are formed to somewhat different shapes, as described below. Each
link has a planar central portion 20 with an enlargement or tongue
22 along and projecting edgewise beyond one edge 24 of the link and
end tongues 26, 28 which also project beyond the link edge 24. The
two links 16, 18 are inverted relative to one another and are
disposed with their planar central portions 20 located side by
side. The links are joined by a center pivot 30 and have end pivot
holes 34, 35 to receive pivots for joining the links to the links
of an adjacent link pair of the respective lazy tong frame 12, as
described below. The axes of the center pivot 30 and end pivot
holes 34, 35 of each link are located in a common plane of the
link. In the particular embodiment illustrated, the three pivot
axes of each link are located in a common longitudinal link plane
containing the link edge 24. The center and end pivot axes of the
links, that is the axis of the center pivot 30 and end pivot holes
34, 35, parallel one another and extend normal to a plane parallel
to and passing between the center link portions 20. This plane is
hereafter referred to as an intervening plane.
As will appear from the ensuing description, when the several link
pairs 14 are assembled to form the extensible structure 12, each
link pair has an inner side facing the central axis of the
structure and an opposite outer side. Terms such as "inner,"
"inwardly," "outer," and "outwardly" in the following description
are referenced to these inner and outer sides of the link pair. In
this regard, it is worthy of note at this point that each of the
link pairs is assembled in the structure in a manner such that the
planar center portions 20 of its links 16, 18 are located at the
outer and inner sides, respectively, of the intervening plane
passing between the center portions. For this reason, links 16 and
18 are hereafter referred to in places as outer and inner links,
respectively.
Returning again to the typical link pair 14 of FIG. 5, the center
pivot 30 is closer to the link end pivot holes 34 than to the end
pivot holes 35. Accordingly each link has a relatively short arm 36
and a relatively long arm 38. The links are bent in such a way that
the short arm 36 of the outer link 16 turns inwardly across the
intervening link plane and the long arm 38 of the inner link 18
turns outwardly across this plane. These link arms thus crossover
one another, as shown, to locate the two link ends 26 at the inner
side of the intervening link plane and the two link ends 28 at the
outer side of the plane. The two inner link ends 26 and the two
outer link ends 28 are located in common inner and outer planes,
respectively, parallel to the intervening plane.
Referring to FIG. 1, the several link pairs 14 of each lazy tong
frame 12 are pivotally joined by link end pivots 40 which extend
through the link end pivot holes 34, 35. In this regard, it will be
seen that the several link pairs are arranged with their inner link
ends 26 nearest one end of the frame, i.e. the upper end of the
frame in FIG. 1, and their outer link ends nearest the opposite end
of the frame. The inner link ends 26 of each link pair are located
directly opposite and outward of the outer link ends 28 of the
adjacent link pair and are joined by pivots 40 to the latter link
ends.
In addition to the link pairs 14, each lazy tong frame 12 has end
link pairs 42 and 44 at its ends. The bottom ends link pair 42 has
a pair of planar ends links 46, 48. One end of these end links are
located outward of and joined by pivots 50 to the outer link ends
38 of the adjacent bottom link pair 14. The opposite ends of the
end links 46, 48 are joined by a pivot 52. The top end link pair 44
has a pair of planar end links 56, 58. One end of these end links
are located inward of and joined by pivots 60 to the inner ends 26
of the adjacent top link pair 14. The opposite ends of the links
are joined by pivots 62.
As noted earlier and shown in FIG. 1, the links of the successive
link pairs of each lazy tong frame 12 diminish in length in the
direction of one end of the frame, i.e. the upper end of the frame
in FIG. 1, as a consequence, each frame has a generally
longitudinally tapered configuration and narrows in the direction
of its upper end. The lower end links 46, 48 are equal in length to
the lower long link arms 38 of the adjacent bottom link pair 14.
Similarly, the upper short arms 36 of each link pair 14 are equal
in length to the lower long arms 38 of the adjacent upper link pair
14, and the short arms of the top link pair 14 are equal in length
to the top end links 56, 58.
The several center link pivots 30, 52, 62 of each lazy tong frame
12 are located in a common longitudinal plane of the frame. The
corresponding end pivots 40, 50, 60 are located in common planes
which converge in the direction of the upper end of the frame.
As noted earlier, and shown in the drawings, the three lazy tong
frames 12 are arranged to form the three sides of the triangular
pyramidal structure 10. The three frames are joined at their
corresponding end pivots 40, 50, 60 by rigid generally V-shaped
corner members or brackets 66. Each bracket 66 has sides arranged
at an included angle of 60.degree.. As shown best in FIG. 1, the
sides of each bracket are interposed between corresponding
pivotally joined link ends of the adjacent frames and are pivotally
attached to the respective ends by their end pivots 40, 50, or 60
as the case may be. The lower end links 46, 48 of the frames 12 are
joined by their pivots 52 to mounting brackets 68 which may be
attached to a supporting base 70. The upper end links 56, 58 are
joined by their pivots 62 to a platform 72 for supporting an object
to be deployed or extended away from and retracted toward the
base.
From the foregoing description, it is evident that the three lazy
tong frames 12 and their interconnecting brackets 66 form a
three-dimensional lazy tong structure of hollow triangular
cross-section. The structure is retracted toward the base 70 by
hinging of the several links in lazy tong fashion at their several
pivot points. The corresponding link pairs 14, 42, 44 of the three
frames 12 constitute link sets or tiers of the structure 10. A
highly unique and beneficial feature of the structure resides in
the fact that during its retraction or contraction, these link sets
or tiers telescope or nest one inside of the other, as shown in
FIGS. 2 through 4. The structure is thus retractable to a fully
contracted configuration (FIGS. 2 - 4) wherein the crossing link
arms 36, 38 of the link pairs 14 abut along the link edges 24, and
their several pivot axes are located in a common longitudinal plane
of the links containing the link edges 24. Thus, the fully
contracted structure has an overall length or height, measured
along its extension axis, approximating the combined width of a
folded link pair (FIGS. 3, 4). The structure thus has a large ratio
of deployed or extended length to contracted or stowed length.
During deployment or extension of the structure 10, the corner
brackets 66 move outwardly from the base 70 and inwardly a small
amount toward the structure centerline. This inward movement of the
brackets is proportional to their distance of movement from the
base. The corner brackets are reacted from rotational motion and
binding by the torsional stiffness of the frame links, such that
the bracket sides remain parallel with their original positions and
with each other during deployment. Any tendency for a corner
bracket to twist from its normal position loads all four of its
attached links in torsion. Thus, the links must be torsionally
stiff. This torsional stiffness, plus the fact that side loads on
the structural produce shear forces and moment couples in the
corner bracket pivots, requires that these pivots have only one
degree of rotational freedom, i.e. rotation on their pivot axes, so
as to be able to load the links torsionally.
The differential inward movement of the corner brackets of the
successive link sets or tiers introduces slight reflex bending in
the links in directions perpendicular to their faces or 90.degree.
from the bending loads. Therefore, the links must have bending
stiffness in the planar loading direction but must be flexible in
the normal-to-planar direction and must be torsionally stiff.
Deployment of the present lazy tong structure can be accomplished
by several means, depending on the application. For example, some
or all of the pivot points of the structure may be equipped with
springs which are connected to the adjacent links in such a way
that the springs urge the structure to extended configuration. The
structure may be retracted to stowed configuration in any
convenient way, as by a cable and winch. Other possible deployment
means include ball-screw actuators, hydraulic struts, or a
bellows-type balloon inside the structure which would supply the
thrust for deployment with the structure providing stability.
If desired, locking of the structure in stowed and/or deployed
configuration may be accomplished by the inclusion of latches at
the pivots. These may be releasable or non-releasable depending on
the application.
* * * * *