 |
Description  |
|
|
BACKGROUND OF THE INVENTION
The present invention relates in general to plastic foam swimming pool
covers and more particularly to such covers being liftable above the pool
for opening thereof via a plurality of lifts coupled to the cover at
peripherally spaced lift points.
DESCRIPTION OF THE PRIOR ART
Heretofore rigid swimming pool covers have been proposed employing one or
more lifts coupled to the cover for selectively elevating the cover to
open the pool for swimming. Such pool covers have incorporated a thermally
insulative material including plastic foam. Sheets of plastic foam
material were dispersed inbetween girders or other structural elements of
the cover structure. Examples of such prior art swimming pool covers can
be found in U.S. Pat. Nos. 2,701,881 issued Feb. 15, 1955 and 3,241,157
issued Mar. 22, 1966.
One of the problems with these aforecited swimming pool covers is that they
are relatively costly of manufacture requiring that girders and other
structural elements be welded or riveted to form a frame work to carry the
thermally insulative material.
It is also known from the prior art to provide a rigid plastic foam pool
cover, particularly suited for covering relatively small outdoor circular
above ground pools. In such cases, the cover has been cut from one or more
pieces of relatively thick rigid plastic foam sheet stock and carved or
shaved so as to provide run-off for the upper surface thereof. In the case
of relatively small pools, the cover is lifted off by the user as a
unitary member and in other cases, where the pools are of larger size, the
pool cover is segmented and the segments are fastened together by
appropriate fastening means. When the pool is to be uncovered, the various
segments are unfastened and removed individually by hand.
Although such covers are particularly suited for small pools, they are
relatively inconvenient when employed on large pools that require the
individual segments to be unfastened and removed individually for stacked
storage or the like. Pool covers of this type are disclosed in U.S. Pat.
Nos. 3,528,110 issued Sept. 15, 1970 and 3,683,428 issued Aug. 15, 1972.
It is also known from the prior art to form a non-rigid plastic membrane
type pool cover in situ by pouring a plastic material onto the surface of
the pool allowing the material to harden into a flexible plastic membrane.
Such a pool cover is disclosed in U.S. Pat. No. 3,555,573 issued Jan. 19,
1971.
It is also known in the prior art to form rigid self-supporting building
structures of polyurethane foam by spraying the foam onto an inflated
form. Such building structures are disclosed in U.S. Pat. No. 3,277,219
issued Oct. 4, 1966.
SUMMARY OF THE PRESENT INVENTION
The principal object of the present invention is the provision of an
improved rigid plastic foam swimming pool cover and method of
manufacturing same.
In one feature of the present invention, amorphous plastic foam material is
formed into a shape conforming generally to the periphery of the pool to
be covered and into a shape for covering the swimming pool. The shape is
also suited for lifting as an integral unit from a plurality of lifting
points spaced apart about the periphery of the cover. The plastic foam is
allowed to harden into a rigid structural element of the cover structure
for providing thermal insulation for the pool and allowing the cover to be
lifted from the pool by a plurality of lifts coupled to the cover at
peripherally spaced lift points.
In another feature of the present invention, the amorphous foam material is
formed into the desired shape, generally conforming to the periphery of
the pool, in situ and allowed to harden in place to form a rigid thermally
insulative pool cover structure.
In another feature of the present invention, the amorphous plastic foam
material is formed to the shape of the pool by erecting a form conforming
to the shape of the cover to be fabricated and depositing the amorphous
plastic foam material into or onto the erected form and allowing the
plastic foam material to harden into the desired rigid shape.
In another feature of the present invention, reinforcing structural
elements are embedded in the foam structure of the pool cover for
increasing the rigidity of the cover in use.
In another feature of the present invention, landscaping receptacles are
formed in the upper surface of the cover to receive soil and plants
therein, whereby the pool cover is landscaped.
In another feature of the present invention, the upper surface of the
plastic foam pool cover is provided with a system of pool water conduits
covered by a translucent material for circulation of pool water
therethrough for heating by sunlight, whereby a combined pool cover and
solar heater is obtained.
In another feature of the present invention, the plastic foam pool cover is
formed in a shop from amorphous plastic foam to a shape determined from a
template of the pool to be covered, cut into segments, and reassembled
over the pool.
Other features and advantages of the present invention will become apparent
upon a perusal of the following specification taken in connection with the
accompanying drawings wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic line diagram, in plan view, of a swimming pool cover
incorporating features of the present invention,
FIG. 2 is a sectional view of the structure of FIG. 1 taken along line 2--2
in the direction of the arrows and depicting a plastic foam cover
incorporating features of the present invention,
FIG. 3 is an enlarged sectional view of a portion of the structure of FIG.
1 taken along line 3--3 in the direction of the arrows,
FIG. 4 is an enlarged sectional view of a portion of the structure of FIG.
1 taken along line 4--4 in the direction of the arrows,
FIG. 5 is a view similar to that of FIG. 2 depicting an alternative
embodiment of the present invention,
FIG. 6 is an enlarged sectional view of a portion of the structure of FIG.
5 delineated by line 6--6,
FIG. 7 is an enlarged sectional view of a portion of the structure of FIG.
6 taken along line 7--7 in the direction of the arrows,
FIG. 8 is a view similar to that of FIGS. 2 and 5 depicting an alternative
embodiment of the present invention,
FIG. 9 is a view similar to that of FIGS. 2, 5 and 8 depiciting an
alternative embodiment of the present invention,
FIG. 10 is a partial sectional view similar to that of FIGS. 2, 5, 8 and 9
depicting an alternative embodiment of the present invention,
FIG. 11 is a side elevational view of the pool cover of FIG. 10 taken along
line 11--11 in the direction of the arrows,
FIG. 12 is a schematic plan view, similar to that of FIG. 1, depicting a
pool cover incorporating alternative embodiments of the present invention,
FIG. 13 is an enlarged sectional view of a portion of the structure of FIG.
12 taken along line 13--13 in the direction of the arrows,
FIG. 14 is a top elevational view of a cover incorporating alternative
embodiments of the present invention,
FIG. 15 is an enlarged sectional view of a portion of FIG. 14 taken along
line 15--15 in the direction of the arrows,
FIG. 16 is a sectional view similar to that of FIGS. 2, 5, 8, 9 and 10
incorporating alternative embodiments of the present invention, and
FIG. 17 is an enlarged detail view of an alternative embodiment of that
portion of the structure of FIG. 13 delineated by line 17--17.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIGS. 1 and 2, there is shown a rigid plastic foam pool
cover 11 incorporating features of the present invention. More
particularly, a sheet 12 of relatively thin plastic material, as of 0.003
inch thick polyethylene sheet, is laid into the pool 13 so that the sheet
rests on and is supported by the surface of the water 14 and extends, at
the periphery of the pool, over the lip of the pool 15. A sheet 16 of
pliable material, as of fiberglass, is set into the pool so as to rest
upon the lip of the pool 15 near the upper end thereof and on the plastic
sheet 12 at the surface of the pool to form a shield for the pool cover.
A thin layer of plastic foam material is then cast into or sprayed onto the
inside surface of the plastic sheet 12 extending over the surface of the
pool and onto the inside surface of the fiberglass shield 16. When the
plastic foam material has been deposited to a suitable thickness, as of
1/2 to 1, inch it forms a hollow cup-like shell structure into which are
placed structural support elements 17, such as sheet metal I-beams or
trusses of the form shown in FIG. 3. These structural elements 17 form,
for example, a triangular shaped structure connected together at the
corners of the triangle by means of webs 18, as of sheet metal, secured to
the triangular strengthening members 17 as by sheet metal screws, rivets
or welding. The corners of the triangular support structure 17 are fixedly
secured to lifting arms 19, as of metal plate, extending outwardly of the
pool over the lip thereof to lift structures 21, such as electric or
hydraulic jacks, embedded in the deck of the pool, as more clearly shown
in FIG. 4.
Once the strengthening members 17 have been positioned within the
cup-shaped foam shell structure, the foam cup structure is filled with
amorphous plastic foam as by spraying or casting to a thickness of 6 to 12
inches. In a typical example, the plastic foam material is polyurethane
having a density of between 1.5 and 2.5 pounds per cubic foot. The plastic
foam material 22 bonds to the reinforcing structures 17 is preferably
formed with a slightly convex upper surface at 23 so that rain water and
oter debris does not tend to collect on the upper surface of the cover 11.
The upper surface of the cover 11 is preferably protected by a thin layer
of fibrous concrete, i.e., hydraulic cement including between 0.5 and 4.0%
by volume relatively short reinforcing fibers as of plastic, steel, or
glass. As an alternative, the protective layer 24 may comprise a coating
of fiberglass or ultraviolet resistant rubber paint, as of Hypalon paint.
Referring now to FIGS. 1 and 4, the lift 21 includes, in the example shown,
an electric jack of the type disclosed in U.S. Pat. No. 3,679,174 issued
July 25, 1972 which is embedded in the earth. The lift 21 includes an
outer tubular steel member 25 of rectangular cross-section containing
therewithin, in telescoping relation, a second rectangular tubular member
26 which includes, at its upper end, a stud 27 for passing through an
aligned opening in the lifting arm 19 and being captured thereto via a nut
28 threaded over the end of the stud 27. A compression spring 29 is
captured between the lifting arm 19 and the upper end of the inside
tubular member 26 to allow a certain degree of canting of the lifting arm
relative to the vertical tube 26 as the cover 11 is raised by the jacks
21.
The jack 21 includes a drive transmission portion 31 fixedly secured to the
outer tube 25 and to the earth via bolts embedded in concrete, not shown.
The transmission 31 includes an electrical drive motor 32 which drives a
drive chain 33 via the intermediary of a sprocket 34. The drive chain is
fixedly secured at one end to the upper end of the inside tube 26 and at
the other end to the lower end of the inside tube 26. The drive chain
passes over a pair of idler sprockets 35.
The cover 11 is raised by energizing the respective drive motors 32 via
current fed to those motors via wires 36. The current is derived from a
source such as a battery 37 or other source of DC power 37. Rheostats 38
are provided in series with each of the lines 36 for adjusting the drive
current and thus the speed of the respective motors 32 to compensate for
different loads on different parts of the cover so that the cover will
lift uniformly without undue tilting thereof. When the cover has reached
the upper most extent of travel, respective limit switches, not shown,
interrupt the power to respective drive motors 32 and the cover will
remain in the upper position. When it is desired to lower the cover,
control switch 39 is switched to a negative polarity so as to reverse the
current through the respective motors 32 for lowering the cover. Again a
limit switch senses the lowermost extent of travel of the cover and
de-energizes the respective drive motors 32.
In the cover embodiment of FIGS. 1-4, the cover 11, after fabrication
thereof, is separated from the plastic sheet 12 and the cover 11 floats on
the surface of the water when the water level is sufficiently high in the
pool. When the water level is decreased below some point, the tapered edge
of the cover will abut the inner lip 15 of the pool at about the same
level that the lifting arm 19 comes to rest on the deck of the pool.
Referring now to FIG. 5, there is shown an alternative cover embodiment of
the present invention. In the embodiment of FIG. 5, the foam cover is
formed by spraying or casting plastic foam over the outwardly domed upper
surface of an air bag 41 so that the underside of the foam cover 22 has a
concave shape and so that the resultant cover 22 comprises a sector of a
plastic foam shell structure. In this manner, the foam is placed in
compression for increased strength and rigidity.
In a preferred embodiment, the upper surface of the air bag 41 is made of
aluminized Mylar which bonds to the foam layer 22 to provide additional
reflection of heat back to the pool. The excess portion of the air bag,
not bonded to the foam layer 22, is trimmed after fabrication of the cover
22. The lifting arms 19 and lifts 21 are arranged, for the shell structure
of FIG. 5, in the same manner as previously described with regard to FIGS.
1-4.
Referring now to FIGS. 6 and 7 the rim portion of the shell cover of FIG. 5
is shown in greater detail. More particularly, a retaining ring structure
is embedded near the rim of the shell cover. The retaining ring structure
includes a pair of metallic rings 45 as of steel reinforcing rods or steel
cables extending about the periphery of the cover. A corrugated fiberglass
sheet 46 is carried inside of the rings 45 such that an outwardly directed
force, such as a compressive force exerted via the foam 22 onto the
corrugated fiberglass sheet 46, is transmitted into the reinforcing rings
45 by placing the rings 45 in tension. The reinforcing rings 45 are wired
to the fiberglass sheet 46 via wires 47. The upper end of the fiberglass
sheet 46 also extends into the protective layer 24, as of concrete, to
restrain radial deflection of the concrete or protective layer 24.
Referring now to FIG. 8, there is shown an alternative embodiment of the
present invention. In the embodiment of FIG. 8, the foam shell cover 22 is
formed by sealing a sheet of elastic material 48, as of rubber, 0.001 to
0.010 thick, around the periphery of the pool by means of water-filled or
sand-filled weight tubes 49. The underside of the membrane or sheet 48 is
then pressurized by applying air pressure to the underside of the sheet,
as by blowing air in through the pool skimmer access port.
Plastic foam material 22 is then applied to the upper surface of the
membrane 48 to the desired thickness, as of a few inches. Once a
self-supporting thickness of foam has been applied to the membrane and
allowed to harden into a rigid self-supporting structure, the weight tubes
49 may be removed so that access may be had to the edge of the cover. In a
preferred embodiment, the rim structure including the rings 45 and
corrugated fiberglass sheet 46 is incorporated in the rim of the cover.
The cover is contoured around each of the lifting points 21 so that the
lifting point lies directly below the rim of the cover.
After the cover has hardened to a rigid self-supporting structure, the
cover is raised and an interior lip portion 51 is formed as by spraying or
laying up of foam. The interior lip provides a drip line for condensate so
that the condensate is returned to the pool rather than being collected on
the pool deck. In addition, that portion of the tapered portion of the lip
51 which abuts the lip 15 of the pool serves to self-center the cover and
to facilitate sealing of the cover to the lip of the pool. The lifting
mechanism includes a steel plate 52 embedded in the foam layer 22 and a
ball-socket type coupling fitting 53 couples the plate 52 to the lifting
tube 26 of the jack 21 and permits canting of the cover 22 relative to the
horizontal as may be encountered during the lifting operation.
Referring now to FIG. 9 there is shown an alternative embodiment to the
method of making the cover of FIG. 8. In the embodiment of FIG. 9, the
elastic membrane 48 is held down and sealed to the edge of the pool via
the weight tubes 49, as above described with regard to FIG. 8. However,
the pool is drained so that an operator may apply plastic foam material to
the underside of the elastic membrane 48 from the inside of the pool. A
fiberglass shield 16 extends around the periphery of the pool inside of
the lip 15. In the case where the foam 22 is applied by spraying, suitable
drop cloths, as of 0.001 polyethylene, are provided covering the inside
surfaces of the pool so that the foam material does not collect thereon.
Referring now to FIG. 10 there is shown an alternative embodiment of the
present invention wherein the membrane 48 is stretched across a hinged
ring 50 which has been laid out around the contour of the lip of the pool.
The membrane 48 is stretched across the ring 50 and battened thereto via
battens 40. The membrane 48 is then tensioned into the desired doubly
curved anticlastic shape by means of one or more jacks 54 pushing up on
the elastic membrane 48 in a central region thereof via relatively large
radious of curvature dishes 55. The foam 22 is then applied, as by
spraying or laying up. As in the other embodiments, the fiberglass shield
16 and the reinforcing ring structures 45 and 46 are preferably included
in the foam matrix. As in the embodiment of FiG. 9, the drop sheet 56
prevents coating of the interior walls of the pool with foam and, in
addition, the drop sheet 56 extends over the lip of the pool so as to
prevent bonding of the foam to the concrete deck. As an alternative to
spraying of the foam onto the inside of the stretched membrane 48, the
membrane may be stretched across the underside of the hinged ring 50 and
the foam applied to the top surface of the membrane 48 as previously
described with regard to the embodiment of FIG. 8.
Referring now to FIG. 11 there is shown, in side elevation, a cover made
according to the method of FIG. 10. In the embodiment of FIG. 11, two
mound portions, corresponding to the position of the jack 54 and dish 55,
are provided with receptacles 57 foamed in place to receive either a
potted plant or soil in which landscaping plants are planted. Each of the
receptacles 57 includes a drain line 58 positioned slightly near the
bottom of the receptacle to drain off excess accumulation of water. Vines
are particularly attractive as landscaping plants as they can spread over
a large area of the cover substantially improving the aesthetic appearance
of the cover. In an alternative embodiment, a larger number of smaller
receptacles are incorporated in cover to be planted with shallow-rooted
plants that send out runners and provide good ground cover. Examples of
such plants would include strawberries.
One method for forming the receptacles 57 is to affix either to the upper
surface or the under surface of the membrane 48 a plurality of plastic
planting pots and to connect tubing 58 to a hole provided in the side of
the pot. The pots and tubes 58 are then foamed into place in the foam
layer 22.
As thus far described, the cover 11 has been foamed in situ but this is not
a requirement. For example, a template may be made of the pool perimeter
15 by stretching a 0.001-0.003 inch thick translucent sheet of
polyethylene across the pool and holding the sheet against the deck of the
pool by means of the weight tubes 49. Air is preferably blown in under the
sheet material to avoid the surface tension generated if the sheet comes
in contact with the surface of the water. Thus, just a sufficient amount
of air is blown in under the sheet to hold it generally in the horizontal
plane. Tension is taken up on the sheet around the perimeter of the pool.
Once the sheet is in place, a tracing is made by tracing the lip of the
pool with a marking pen onto the translucent sheet. Such a method for
making a template is described and claimed in my copending U.S.
application Ser. No. 516,204 filed Oct. 21, 1974. Once the template is
obtained it is folded and taken to a shop. The hinged ring 50 is laid out
in the desired perimeter around the lip of the unfolded pool template at
the shop and the membrane 48 is tensioned across the bottom of the ring
50. Inflatable bags disposed under the membrane 48 are utilized instead of
the jacks 54 and dishes 55 to tension the membrane 48 into the desired
doubly curved shape. Plastic foam is applied to the upper surface of the
tensioned membrane 48, in the manner as previously described with regard
to FIG. 10.
The resultant plastic foam shell cover is cut into sections eight feet wide
for ease of handling and shipment from the shop to the pool site. At the
pool site, the segments 59 are reassembled and glued together by a
suitable adhesive such as contact cement. In case the reinforcing ring
structure including the reinforcing rings 45 and corrugated fiberglass
sheets 46 were embedded in the lip of the cover, the reinforcing ring
structure was either fabricated in sections corresponding to the cuts to
be made or such ring structure was severed at the time the transverse cuts
were made for segmenting the foam cover. When the cover is reassembled at
the pool site the reinforcing rings 45 are welded together to provide a
continuous ring. After such welding, additional foam material is filled in
around the region of the welds. The reassembled cover is coated with the
protective coating 24, as of fibrous concrete or fiberglass.
Referring now to FIGS. 12 and 13, there is shown an alternative embodiment
of the present invention. In the pool cover 11 of FIGS. 12 and 13, the
reinforcing wire mesh is embedded in the foam to provide increased
strength and rigidity for the cover. More particularly, a vertical grid
pattern of reinforcing steel wire mesh 61 is laid on top of a first wire
mesh 62 which is laid out horizontally on top of an initial layer of
plastic foam formed upon the surface of the pool. The vertically directed
intersecting wire meshes 61 are secured, as by wiring, welding or the
like, to the bottom horizontal mesh 62. Additional foam is then applied to
embed the lower mesh 62 in the foam and to embed a portion of each of the
vertically directed meshes 61 in the foam. Air inflated plastic bags 63
are then laid into the space between the intersecting vertical meshes 61
and foam is applied so as to embed the bags 63 in the thickness of the
cover. A second horizontal reinforcing wire mesh 64 is then laid on top of
the foamed bags 63 and anchored to the vertical meshes 61 as by wiring.
Additional foam is then laid in on top of the upper mesh 64 so as to embed
mesh 64 in the foam cover. The cover is covered with the protective layer
24, as aforedescribed. The lifting arms 19 are connected to the lower
horizontal mesh 62.
Referring now to FIGs. 14 and 15 there is shown an alternative embodiment
of the cover of the present invention wherein the upper surface of the
foam cover is grooved at 65 to provide a multitude of parallel solar
heating water channels extending over the upper surface of the foam cover
11. An input distribution manifold channel 66 extends along one side of
the cover in fluid communication with each of the laterally directed
channels 66. Similarly, a collection manifold channel 67 is formed
communicating with each of the lateral channels 65 on the other side of
the cover 11. The upper surface of the grooves 65 is coated with an
ultraviolet resistant opaque and preferably dark pigmented material such
as dark blue or black Hypalon rubber.
A translucent fiberglass sheet 68 is formed covering over the channels 65,
66 and 67. The fiberglass cover 68 is preferably bonded to the land
portions between adjacent grooves 65. Pool water to be heated is piped
into the input distribution channel 66 via a flexible hose 69 connected at
one end to a pool return line at the inside of the pool and at the other
end to a pipe embedded in the foam cover and communicating with the input
distribution manifold 66. The flexible hose 69 has sufficient length so
that when the cover 11 is raised to its uppermost position the hose 69
extends from the cover to the pool return line inlet. Similarly, a second
hose 71 is connected into the output or collection manifold 67. The hose
71 extends from the collection manifold 67 to the pool for returning the
heated water to the pool when the cover is in the raised position. A
valve, not shown, at the pool equipment pad is operated by a timer or by a
thermal sensor for sensing the solar energy falling upon the cover for
directing the pool water through the solar heating channels only if
sufficient solar energy is falling upon the cover to result in significant
heating of the pool water.
Referring now to FIG. 16, there is shown an alternative embodiment of the
pool cover 11 wherein tie rods 72 extend both laterally and longitudinally
of the cover 11 for tying together the ring structure 45 and 46 to prevent
radial movement of the ring structure. The tie rods 72 are affixed at
their ends to rings 45 and are embedded in webs 73 of foam material
extending downwardly from the foam shell structure forming the cover.
Referring now to FIG. 17 there is shown an alternative embodiment of the
mesh reinforced foam cover of FIGS. 12 and 13. In the embodiment of FIG.
17, the lower horizontal reinforcing mesh 62 is eliminated and the foam is
foamed in place over a grid of inflated bags 63. Vertical intersecting
meshes 61 are disposed in between the bags 63. Reinforcing bars 74 are
laid into the spaces between the bags and are connected, as by wiring or
welding, to the lower end of the vertical meshes 61. The intersecting
reinforcing bars 74 are tied together at their points of intersection as
by wiring or welding and the bars 74 are embedded along with the mesh 61
in the foam. The upper extremeties of the vertical mesh 61 is tied into
the upper horizontal mesh 64.
After the cover has been formed it is coated on the upper and lower
surfaces with a protective coating 24, as of fiber reinforced concrete or
fiberglass. The coating adds considerably to the strength of the cover
and, in addition, the trapped air pockets formed in the lower surface of
the cover serve to reduce the surface tension which might otherwise be
developed for a relatively flat cover, such as that shown in FIGS. 12 and
13.
* * * * *
|
|
 |
|
 |
Description |
|
