Safety edge for a door

A safety door edge switch including a flexible sheath, an internal resiliently compressible foam formation in the sheath and providing fluid communication therealong, a relatively rigid transverse structure at one region in the sheath and containing a pressure sensitive switch element communicating with the inner formation for sensing pressure throughout the sheath and a pair of spaced confronting flexible contact sheaths engageable to provide a secondary switch.

BACKGROUND OF THE INVENTION 
This invention is concerned with safety door edges as in heavy over-head 
doors to protect personnel, equipment, and the door from damage by impact; 
as well as for use in doors for elevators, mass transit vehicles, and the 
like, wherein an extremely high degree of reliability is a requirement, as 
well as substantial versatility for use under many different 
circumstances. 
SUMMARY OF THE INVENTION 
It is an important object of the present invention to provide a door edge 
switch construction for use in the broad field discussed above, wherein 
may be obtained extremely high sensitivity to external pressure, as well 
as the reliability of a back-up or redundant switch system, which may be 
selectively employed as a plural switch system for actuating a plurality 
of operators. 
It is a more particular object of the present invention to provide a highly 
improved safety door edge switch having the advantageous characteristics 
mentioned in the preceeding paragraph wherein a pressure sensitive switch 
element may be protectively encased in the door edge construction itself, 
as well as the door edge provided with internal contact elements for 
connection to an exterior circuit as a redundant, alternative, sequential, 
or other desired combination of switches. 
Other objects of the present invention will become apparent upon reading 
the following specification and referring to the accompanying drawings, 
which form a material part of this disclosure. 
The invention accordingly consists in the features of construction, 
combinations of elements, and arrangements of parts, which will be 
exemplified in the construction hereinafter described, and of which the 
scope is indicated by the appended claims.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now more particularly to the drawings, a building wall is shown 
at 10 in FIG. 1, having a doorway 11 provided with a door 12. While the 
door illustrated at 12 is an overhead door, having a safety edge 13 of the 
present invention along its lower side or leading edge, the device of the 
present invention is equally applicable for use with vertically disposed, 
horizontally moveable doors and other closures, as desired. 
The safety edge 13, see FIG. 2, extends along the lower or leading edge 15 
of the door 12, which door portion may be provided with an elongate, 
female dovetail or similar configuration, as at 16. 
The door edge construction 13 may include an outer casing or sheath 18 of 
elongate, generally constant cross-sectional outline configuration, 
extending closely along the underside or edge 15 of the door 12. The 
casing or sheath 18 may advantageously be fabricated of form retaining, 
but flexible material, such as rubber, having a bottom wall 19 for 
engagement with the door threshold or ground, side walls 20 and 21 
upstanding integrally from opposite side edges of the bottom wall, and a 
top wall 22 extending between upper edges of the side walls in close 
facing relation with the leading door edge 15. The sheath 18 may be 
further formed with a male, dovetail formation 23 upstanding along the top 
wall 22 for interfitting engagement with the door edge formation 16, 
facilitating quick and easy mounting, removal and replacement of the door 
edge 13 with respect to the door 12. 
Opposite ends of the sheath 18 are closed and sealed, as by end walls 25 
and 26, and provided interiorly of the sheath 18, at least at one region 
thereof, is a relatively stiff or rigid transverse formation, as at 27, 
extending entirely across the sheath, so as to effectively prevent or 
minimize compression of the sheath at that location. In the illustrated 
embodiment, the relatively stiff or rigid transverse structure 27 is shown 
at one end, the left hand end of the sheath. The relatively rigid 
structure 27 may be of a configuration conformable to the internal 
cross-sectional configuration of the sheath 18, and fabricated of 
relatively stiff material, such as firm rubber or plastic. If desired, 
more than one relatively incompressible transverse structures, as at 27, 
may be provided in the sheath 18, say at spaced locations therealong. 
Substantially fully occupying the remainder of the sheath 18, except that 
occupied by the transverse structure 27 may be a resiliently compressible 
inner formation 30, extending longitudinally along the interior of the 
sheath. The compressible formation 30 is fabricated essentially of foam, 
and includes an elongate inner or upper foam strip 31 extending closely 
along the inner side of the sheath top wall 22, substantially co-extensive 
therewith, except for the space occupied by the transverse structure 27. 
A similar lower, or outer foam strip 32 may be substantially congruent to 
the upper or inner foam strip 31, being in generally parallel, facing, 
spaced relation with respect to the latter, and extending closely along 
and substantially co-extensive with the lower or outer sheath wall 19. 
That is, the outer foam strip 32 substantially completely occupies the 
interior face of the outer sheath wall 19, except for that occupied by the 
transverse structure 27. 
In addition, an intermediate foam strip 33 is interposed in sandwiched 
relation between the inner and outer foam strips 31 and 32, being of an 
outline configuration substantially congruent to that of the inner and 
outer foam strips. However, the intermediate foam strip 33 is provided 
with a plurality of vertically extending, through openings, as at 34, 35, 
36 and 37 arranged in a series or row longitudinally of the intermediate 
strip, and spaced apart from each other by transverse partitions or walls, 
as at 38 and 39 remaining between the openings or through holes. Also, the 
openings or through holes 34-37 are spaced from the end surfaces of the 
intermediate strip 33 to leave end walls, as at 40 and 41, for the end 
openings or holes 33 and 37. 
As the vertically extending, through holes or openings 34-37 are interposed 
between the upper and lower foam strips 31 and 32, it will be apparent 
that the openings are closed by the upper and lower strips, and combine 
therewith to define essentially closed cavities or chambers of the 
openings 34-37. 
It is essential that the several openings or chambers 34-37 be in fluid 
communication with each other, in order to transmit therebetween pressure 
changes occurring by external pressure applied to the sheath 18. If 
desired, the foam of the intermediate layer 33 may be of the open cell 
type for communication between chambers 34-37 through the cells of the 
partitions 38 and 39. Alternatively, the foam of intermediate layer 33 may 
be of the closed cell type where this structure is desirable, and there be 
provided passageways or conduits through the intermediate partitions 38 
and 39, as at 44 and 45. 
Protectively located in the relatively rigid transverse structure 27, as at 
46, is a fluid pressure sensitive switch element, which may be of the type 
manufactured by Micro Pneumatic Logic, Inc. of Fort Lauderdale, Fla., or 
equivalent. The pressure sensitive switch element 46 is effectively 
protected, as by imbedding or otherwise enclosing within the rigid 
structure 27, and includes a pressure port or nipple 47 communicating 
through the end partition and into the adjacent end chamber 34. The 
pressure sensitive switch element 46 is provided with electrical 
conductors as at 48 and 49 extending in sealed relation outwardly from the 
sheath 18 for connection in desired control circuitry. 
Thus, the pressure sensitive switch element 46 is in pneumatic 
communication from its mounting in the transverse structure 27 throughout 
the entire interior of the sheath 18 through the fluid passage means 
defined by the series of openings 34-37 and intermediate conduit means, as 
at 44 and 45. Thus, upon the application of external pressure to the 
sheath 18, anywhere therealong except at the location of structure 27, 
increased internal pressure in the several chambers 34-37 is communicated 
to the switch element 46 to actuate the latter for effecting a desired 
result. Further, the switch is protectively enclosed in the transverse 
structure, which also serves upon normal ground engagement of the door 12, 
to prevent pressure increase and actuation of the switch element. 
In addition to the foregoing, the present invention may include a pair or 
upper and lower, flexible, conductive sheets, say of aluminum foil or the 
like, as at 50 and 51. These conductive sheets are on opposite, upper and 
lower sides of the intermediate foam strip, being respectively sandwiched 
therebetween and the upper and lower foam strips 31 and 32. That is the 
upper or inner conductive sheet 50 is sandwiched between the intermediate 
foam strip 33 and upper foam strip 31, while the lower or outer conductive 
sheet is sandwiched between the intermediate foam strip and the lower or 
outer foam strip 32. The upper and lower conductive sheets 50 and 51 
extend, respectively, over and under the several openings 34-37 in the 
intermediate strip, being in spaced, confronting relation with respect to 
each other through the several openings. Upon the application of external 
pressure to the sheath 18 except at the location of transverse structure 
27, the conductive sheets 50 and 51 may be deflected into and through a 
respective chamber for electrically conductive engagement with each other. 
Connected to respective conductive sheets 50 and 51 are conductors 52 and 
53, which may pass in sealed relation exteriorly of the sheath 18 for 
connection to suitable circuitry. Thus, the conductive sheets 50 and 51 
combine to define a pressure sensitive switch construction in addition to 
that of switch 46. 
The relative sensitivity may be selected, as by adjustment of the switch 
element 46 and selection of the densities and thicknesses of foam elements 
31, 32 and 33. If desired, the switch construction of sheets 50 and 51 may 
be redundant to or a back-up for that of switch element 46, or vice-versa. 
Further, one switch element may operate in sequence with the other, as for 
controlling a plurality of separate functions, as in the stopping and 
reversing of door movement, or other desired functions, all for great 
reliability and versatility in operation. 
Although the present invention has been described in some detail by way of 
illustration and example for purposes of clarity of understanding, it is 
understood that certain changes and modifications may be made within the 
spirit of the invention.