Quick disconnect assembly

A quick disconnect assembly (20) provides for the releasable attachment of a fixture, such as a helicopter seat frame (26), to a support structure, such as the interior structure of the aircraft cabin (28). The assembly includes a tie down stud (100) having a substantially spherical outer surface (182) and a threaded bolt (188) extending therefrom for attachment to the support structure. An attachment fitting (22) is provided having a main body (40) with means for attachment (56) to the fixture. A plurality of grip arms (148) are pivotally associated with the main body. The arms have inwardly curved ends (156) for cooperating with the spherical outer surface of the stud to engage the stud by positioning the arms inwardly. With the attachment fittings secured to the tie down stud, the attachment fitting is movable relative to the stud through a predetermined angle.

TECHNICAL FIELD 
The present invention relates to a quick disconnect assembly and more 
particularly to such an assembly which permits nonload inducing angular 
movement between components of the assembly. 
BACKGROUND ART 
Some aircraft cabin interior structures are attached to the fuselage 
structure by quick disconnect attachment fittings. For example, pilot and 
passenger seats in many helicopters, as well as in other types of 
aircraft, are attached to the fuselage structure using a quick disconnect 
assembly. This permits the easy installation and removal of seats when 
repair or removal of fuselage components or the seats is required. 
While such attachment fittings have provided for quick removal and 
installation of these components, the connection has generally provided a 
rigid attachment between the fuselage structure and the seat frame. As a 
result, in the event of a helicopter crash, relative movement between the 
fuselage structure to which the seat is attached and the seat frame itself 
induces substantial bending or prying forces. These forces can result in 
the failure of the attachment assembly and thereby permit the release of 
the seat from the fuselage structure. In the event the seat becomes 
disengaged from its attachment to the fuselage, the safety of the 
passengers or pilot is greatly jeopardized. 
DISCLOSURE OF THE INVENTION 
The present invention recognizes the benefit which is derived from 
providing a quick disconnect attachment between the fuselage structure and 
components such as pilot and passenger seats which would permit relative 
movement between the fuselage structure and the seat frame without 
inducing bending or prying forces at the point of attachment. The quick 
disconnect assembly according to the present invention provides for the 
releasable attachment of a fixture, such as a helicopter seat frame, to a 
support structure, such as the interior structure of the aircraft cabin. 
The assembly includes a tie down stud having a substantially spherical 
outer surface and structure for attachment of the stud to the support 
structure. An attachment fitting is provided having a main body with means 
for attachment to the fixture and a plurality of grip arms pivotally 
associated with the main body. The arms have inwardly curved ends for 
cooperating with the spherical outer surface of the stud to engage the 
stud by positioning the arms inwardly. Even though engaged with the stud, 
the main body is movable relative to the stud through a predetermined 
angle. In a preferred embodiment of the invention, the main body is 
movable through an angle of approximately 10.degree. from alignment with 
the stud. While this particular angular movement is identified in the 
preferred embodiment of being on the order of 10.degree., it will be 
appreciated by those skilled in the art that a lesser or greater degree of 
movement can be provided without departing from the spirit of the present 
invention. 
In accordance with a more specific embodiment of the invention, the main 
body has a spherical head extending therefrom and the tie down stud has a 
spherical indention formed therein for receiving the spherical head. A 
substantially uniform thickness wall is formed between the spherical 
surface and the indention. 
The main body includes a cylindrical shaft having an annular flange 
extending radially outwardly from the shaft with the spherical head 
extending from the end of the shaft adjacent the flange. The grip arms 
have an engaging lip on one end thereof spaced from the inwardly curved 
ends for engaging the flange. Springs are positioned between the stud and 
the arms for normally urging the arms radially outwardly. A locking sleeve 
is engaged around the gripping arms and is movable between a first 
position wherein the gripping arms are spread outwardly under the action 
of the springs and a second position wherein the gripping arms are 
positioned inwardly for engagement adjacent to the tie down stud. Upon 
engagement of the spherical head within the spherical indention of the 
stud, appropriate clearance is provided between the upper uniform 
thickness wall of the tie down stud and the flange formed on the main body 
to permit angular rotation of the main body relative to the stud. As a 
result of this geometry, a ten degree movement of the cabin structure 
relative to the seat frame structure can occur without introducing bending 
forces between the tie down stud and the quick disconnect main body.

DETAILED DESCRIPTION 
Referring to FIG. 1, a quick disconnect assembly 20 includes a main body 
assembly 22 for releasable attachment to a floor attachment assembly 24. 
In the embodiment illustrated, quick disconnect assembly 20 is used for 
attachment of a seat leg 26 to the cabin floor panel 28 of an aircraft, 
such as a helicopter. 
Main body assembly 22 includes a main body 40 having a lock sleeve 42 
slidably engaged over body 40. As will be described hereinafter in greater 
detail, sleeve 42 is movable longitudinally relative to body 40. Sleeve 42 
has a shank portion 44 with an annular flange 46 formed at one end 
thereof. A lock arm 48 operates in an annular groove 50 formed in flange 
46. Lock arm 48 is pinned to flange 46 by pin 52 and is biased by a 
compression spring 54 entrapped between one end of lock arm 48 and flange 
46. A connecting bolt 56 is threadedly received within main body 40. Main 
body assembly 22 is connected to seat leg 26 by positioning bolt 56 
through an aperture in lower flange 60 of seat leg 26 and engaging a nut 
62 thereon to fix main body assembly 22 to flange 60. 
Floor attachment assembly 24 includes a dish-shaped floor fitting 70 
consisting of a circular dish body 72 with a flange 74 extending 
therefrom. Floor fitting 70 is permanently secured to floor panel 28, the 
fitting being attached into the floor panel upon its construction. As is 
seen in FIG. 1, floor panel 28 includes a central core 80 between a lower 
skin 82 and an upper skin 84. The panel is originally formed with a 
circular cutout 86 in core 80 somewhat larger than the diameter of dish 
body 72. Floor fitting 70 is then affixed within the circular cutout using 
an appropriate adhesive 88 with the bottom of the floor fitting resting 
against lower skin 82. Flange 74 is positioned immediately below upper 
skin 84 as shown. In this way, floor fitting 70 is permanently fixed 
within the floor panel 28. 
Floor attachment assembly 24 includes a tie down stud 100 which is attached 
to floor fitting 70 and lower skin 82 of floor panel 28 using an 
appropriate nut 102. A washer 104 is positioned between nut 102 and lower 
skin 82 as shown. 
Referring now to FIGS. 2 through 5 and particularly FIGS. 3 through 5, main 
body 40 has an upper body portion 108 with an internal thread 110 formed 
longitudinally therethrough for receiving threaded bolt 56. Main body 40 
has an intermdiate annular locking groove 112 formed around the entire 
circumference of the main body with four fixed legs 114 (FIG. 5) extending 
from upper portion 108. An outturned angular lip 116 (FIG. 5) is formed on 
the end of legs 114 remote from body portion 108. 
Referring to FIG. 4, bolt 56 has a spherical end 130 leading to an annular 
flange 132 having a plurality of cylindrical spring receiving countersunk 
holes 134 formed therein. Opposite the spherical end 130 from flange 132 
is an unthreaded shaft portion 136 leading to a threaded end 138. 
Referring now to annular flange 132, a ledge 140 is formed by flange 132 
opposite spherical end 130. Surface 142 of flange 132, adjacent the 
spherical end, is angled upwardly from the spherical end as shown. 
An aperture 144 is formed in the threaded end of shaft portion 136 and 
receives a spring pin 146 therethrough to fix bolt 56 relative to main 
body 40. 
Grip arms 148 cooperate with bolt 56 to engage tie down stud 100 as will 
hereinafter be described. Grip arms 148 include uniform central portion 
150 having an engaging foot 152 on one end defining a step 154. The end 
opposite foot 152 has a radially inwardly facing curved lower portion 156. 
As is seen in FIG. 4, with lock sleeve 42 engaged downwardly over grip 
arms 148, the arms are engaged inwardly against the outwardly facing 
surface of flange 132 compressing springs 135 received within countersunk 
holes 134. In this engaged position, the radius of curvature of the lower 
portion 156 of arms 148 has approximately the same center as the radius of 
curvature of spherical end 130 of bolt 56. Further, step 154 on grip arms 
148 is engaged with ledge 140 of flange 132. 
As can be seen in FIGS. 2 and 4, lock arm 48 has a notch 170 in one end 
thereof for receiving one end of spring 54. The opposite end of spring 54 
is received in a countersunk bore 172 formed in upper flange 46 of sleeve 
42. Spring 54 acts to bias lock arm 48 about pin 52 engaging the end 
opposite notch 170 against main body 40. When sleeve 42 is in the position 
shown in FIG. 4 such that lock arm 48 registers with annular locking 
groove 112, the lock arm is engaged within groove 112, and prevents the 
sliding movement of the lock sleeve. Disengagement of the lock arm is 
achieved by depressing lock arm 48 adjacent notch 170 to compress spring 
54, causing the disengagement of the opposite end of lock arm 48 from the 
annular locking groove 112. 
Referring to FIGS. 3 and 4, tie down stud 100 includes a spherical head 180 
having a spherical outer surface 182 and a spherical indention 184 with an 
upper flat 186 joining the two. A threaded bolt 188 extends from spherical 
head 180 with a positioning collar 190 therebetween. As can be seen in 
FIG. 4, a spherical wall of substantial uniform thickness is formed 
between spherical outer surface 182 and spherical indention 144 of head 
180. As has been described above, stud 100 is attached to floor fitting 70 
and lower skin 82 of floor panels 28 by nut 102. 
As can be seen in FIG. 4, the upper flat 186 between spherical outer 
surface 182 and spherical indention 184 of head 180 slopes downwardly from 
indention 184 to spherical surface 182. As is shown in FIG. 4, with main 
body 40 aligned with stud 100, the angular position between this flat 186 
and end 142 on bolt 56 is defined by the angle .beta.. In a preferred 
embodiment, this angle is on the order of 10.degree.. 
Referring to FIG. 6, with lock sleeve 42 engaged in the lock position as 
illustrated in FIGS. 1-6, such that grip arms 148 are engaged inwardly 
adjacent spherical head 180 of stud 100, bolt 56 may still be rotated 
through the angle .beta. relative to stud 100 without inducing bending 
forces between the two components. In effect, seat leg 26 may then be 
rotated through a 10.degree. arc relative to floor panel 28 without 
introducing any bending forces in the quick disconnect assembly. 
Disconnection of main body 40 from tie down stud 100 is illustrated in 
FIGS. 7 and 8. Release is quickly and easily achieved by depressing lock 
arm 48 to compress spring 54 (FIG. 2), thereby disengaging the lock arm 
from annular locking groove 112. Sleeve 42 is then slid longitudinally 
along main body 40 upwardly as seen in FIG. 7. Upon upward movement of 
sleeve 42, grip arms 148 swing outwardly under the action of springs 135 
releasing engagement with spherical head 180. As is seen in the 
perspective view of FIG. 8, the release of grip arms 148 permits the 
disengagement of main body assembly 22 from tie down stud 100. 
Thus, the present invention provides for a quick disconnect assembly for 
releasably attaching a component such as the pilot or passenger seat frame 
to the aircraft cabin floor structure. In the connected position, the 
present invention permits movement of the seat frame relative to the cabin 
interior structure without inducing bending forces on the quick disconnect 
assembly. It will be appreciated that the movement permitted between the 
main body assembly and the tie down spherical head stud permits a movement 
from axial alignment in any direction to a maximum canted position. In the 
embodiment disclosed, the movement permitted is on the order of 10.degree. 
from axial alignment. 
Although preferred embodiments of the invention have been described in the 
foregoing detailed description and illustrated in the accompanying 
drawings, it will be understood that the invention is not limited to the 
embodiments disclosed, but is capable of numerous rearrangements, 
modifications and substitutions of parts and elements without departing 
from the spirit of the invention. Accordingly, the present invention is 
intended to encompass such rearrangements, modifications and substitutions 
of parts and elements as fall within the spirit and scope of the invention 
.