Conveyors – chutes – skids – guides – and ways – Chutes – Flexible wall
Reexamination Certificate
1999-04-06
2001-03-13
Skaggs, H. Grant (Department: 3651)
Conveyors, chutes, skids, guides, and ways
Chutes
Flexible wall
C441S084000, C441S044000, C441S040000, C156S322000, C242S118310
Reexamination Certificate
active
06199676
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to inflatable structures, and more particularly to inflatable tubular structures with helical seams.
2. Description of the Related Art
It is known in the prior art to construct inflatable structures of several pieces of material adhesively bonded together to form tubular members impervious to air and water. Such inflatable tubular members are often utilized in water floatation devices such as life rafts and inflatable evacuation devices for commercial aircraft.
As illustrated in
FIGS. 1 and 2
, a body of a prior art inflatable annular floatation device or raft
10
comprises four tubular segments
12
,
14
,
16
and
18
that are constructed of water and air impervious material. The tubular elements are adhesively bonded together at transverse circular seams
20
,
22
,
24
, and
26
. Each segment is arcuate in shape and includes a lower wall
28
adhesively bonded to an upper wall
30
at an inner seam
32
and an outer seam
34
. Thus, the annular floatation device
10
comprises a total of twelve adhesively bonded seams that may be subject to leakage due to improper assembly, over-inflation of the floatation device
10
, cyclic loading and unloading due to inflation and deflation, wear, and the like. Overlapping or cross-over seam areas at the intersections of the inner and outer seams and the transverse seams are especially vulnerable to leakage.
During construction of the prior art floatation device
10
, and with additional reference to
FIG. 3
, each segment
12
,
14
,
16
and
18
is manually formed by cutting woven material such that the warp
36
of the material is oriented parallel to the longitudinal axis
40
of the tubular member and the fill
38
is oriented transverse to the longitudinal axis. As shown, the warp
36
extends parallel to the seams
32
and
34
in order to prevent twisting of the floatation device
10
during inflation and operation. However, such warp direction requires special orientation of fabric during the cutting which further complicates the assembly process and results in a significant amount of material waste. Moreover, each wall
28
,
30
of each segment must be laid out separately prior to applying adhesive. A substantial amount of labor is therefore required to piece the walls and segments together.
The above-described problems are further augmented by the long curing time of adhesives used to bind the seams together. The formation of each seam requires the application of a suitable layer of adhesive between overlapping areas of the walls and segments. Each seam must be formed separately and typically must be cured for at least four hours before forming a subsequent seam, which also must be cured for at least four hours, and so on. Inflating and testing the floatation device
10
cannot take place until the final seam is completely cured. With a total of twelve seams for the prior art annular floatation device
10
, much manufacturing time is lost due to the long curing process.
Another drawback associated with this prior art inflatable arrangement is illustrated in FIG.
4
. As shown, the outer seam
34
and inner seam
32
of each tubular segment
12
,
14
,
16
and
18
are subject to a circumferential force F
c
when the device
10
is inflated. The circumferential force F
c
extends normal to the seams
32
and
34
and therefore equals the normal force F
n
acting on the seams. The normal force F
n
tends to pull the seams
32
and
34
apart. This is especially prevalent when the device
10
is over-inflated or when too much external force is applied to the walls of the inflatable device
10
.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an inflatable device in general and an inflatable evacuation or floating device in particular that reduces manufacturing time and material waste.
It is a further object of the present invention to strengthen the seams while reducing the amount of normal force normally acting on the seams to thereby provide a high degree of reliability of the inflatable device.
It is an even further object of the present invention to provide an inflatable device that is relatively inexpensive and easy to manufacture.
According to one aspect of the present invention, an inflatable evacuation device includes at least a first inflatable tubular member, a second inflatable tubular member spaced from the first inflatable tubular member, and a floor extending between the first and second inflatable tubular members. Each of the first and second inflatable tubular members are constructed of an elongate, flexible strip of woven fabric that is substantially impervious to air and water. The elongate strip has a first elongate edge and a second elongate edge extending substantially parallel to the first elongate edge. The elongate strip is spiraled into a tubular shape such that the first elongate edge is adjacent the second elongate edge to thereby form a spiral seam. Preferably, first and second tape members are thermobonded to the inner and outer surfaces, respectively, of each tubular member along the length of the spiral seam. A warp direction of the woven fabric is preferably substantially parallel to the spiral seam while a bias direction of the fabric extends along a circumference of each tubular member.
According to a further aspect of the invention, an inflatable annular floating structure comprises an inflatable tubular member that is constructed of an elongate, flexible strip of woven fabric that is substantially impervious to air and water. The elongate strip has a first elongate edge and a second elongate edge extending substantially parallel to the first elongate edge. The elongate strip is spiraled into a tubular shape such that the first elongate edge is adjacent the second elongate edge to thereby form a spiral seam and inner and outer tubular surfaces. A first elongate tape member is bonded to one of the inner and outer surfaces of the tubular member along the spiral seam. Preferably, the first elongate tape member is bonded to the inner surface of the tubular member along the spiral seam for sealing the spiral seam. A second elongate tape member can be bonded to the outer surface of the tubular member along the spiral seam for reinforcing the spiral seam.
According to an even further aspect of the invention, a method of forming an inflatable structure includes the steps of: providing an elongate, flexible strip of woven fabric that is substantially impervious to air and water, the elongate strip having a first elongate edge and a second elongate edge extending substantially parallel to the first elongate edge, with a warp direction of the woven fabric extending substantially parallel to the first and second elongate edges; spiraling the elongate strip into a tubular member such that the first elongate edge is adjacent the second elongate edge to thereby form a spiral seam and inner and outer tubular surfaces; and bonding at least a first elongate tape member to one of the inner and outer surfaces of the tubular member along the spiral seam. Preferably, the first elongate tape member is bonded to the inner surface of the tubular member along the spiral seam for sealing the spiral seam and a second elongate tape member is bonded to the outer surface of the tubular member along the spiral seam for reinforcing the spiral seam.
Preferably, the bonding step includes thermobonding the first and second elongate tape members to the inner and outer surfaces, respectively, of the tubular member.
There are, of course, additional features of the invention that will be described hereinafter which will form the subject matter of the appended claims. Those skilled in the art will appreciate that the preferred embodiments may readily be used as a basis for designing other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions since they do not depa
Air Cruisers Company
Fridman Lawrence G.
Ridley Richard
Skaggs H. Grant
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