Swimming pool cover assembly

An assembly for covering a swimming pool when it is not in use. A roll member is rotatably mounted at one end of the pool for rolling up and unrolling a sheet of material of dimensions for covering the pool. A scissor type extension device moves the outer end of the sheet toward the other side of the pool when unwinding. The scissor device is moved between the retracted and extended positions by a rotating screw. An electrical motor rotates the screw and the roll member. A slide track mechanism submerges the entire assembly when rolled up.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates in general to swimming pools, and more particularly 
to a pool cover with an automatic opening and covering system. 
2. Description of the Prior Art 
Covering a swimming pool while not in use has several advantages. It 
reduces evaporation, retains heat in the water, and keeps the pool 
clearer. It also may prevent a small child from stumbling into an 
unattended pool. A disadvantage is that a tough vinyl covering is bulky 
and fairly difficult to roll out and unroll. 
A mechanism for automatically extending and retracting a cover is known. It 
has tracks mounted on each side of the pool, a roll member for the cover, 
and an electric motor. The motor pulls ropes that are sewn into the sides 
of the cover to extend it. Once retracted, the rolled up cover remains at 
the end wall of the pool, or on the area immediately behind the end of the 
pool wall. These prior art mechanisms required modifications the length of 
the pool that detracted from the normal beauty and usefulness of the sides 
of the pool. 
SUMMARY OF THE INVENTION 
It is a general object of this invention to provide an improved pool cover 
assembly for automatically covering and uncovering a pool without 
requiring extensive modifications along the sides of the pool. 
It is a further object of this invention to provide an improved pool cover 
assembly for automatically covering and uncovering a pool that has an 
improved device for extending the cover over the pool, yet does not 
require tracks alongside the pool. 
It is the further object of this invention to provide an improved pool 
cover assembly for automatically covering and uncovering the pool that 
also submerges the rolled up cover at the end of the pool when retracted. 
In accordance with these objects, this invention provides a pool cover 
assembly comprising: 
accumulation means for accumulating a flexible sheet of material at one end 
of the pool; 
a flexible sheet of material of dimensions sufficient to cover a 
substantial part of the pool, having an inner end secured to the 
accumulation means; 
extension means for moving the outer end of the sheet toward the opposite 
end of the pool from the accumulation means, the accumulation means being 
adapted to allow the extension without tangling; and 
submersion means for submerging the accumulation means into the pool for 
storage and for surfacing for extension. 
In accordance with a preferred embodiment of this invention, a pool cover 
assembly is provided that uses a scissor type extension device. A roll 
member is mounted to one end of the pool for winding the cover on an off. 
Rods in pairs are pivotally secured together in a crisscross pattern and 
mounted to the pool wall below the roll member. Closing the ends of the 
rods extends the length, and opening the ends retracts the rods. The free 
ends of the outer pair of rods are slidably carried by the outer end of 
the cover. A screw opens and closes the rods as the motor is winding or 
unwinding to cover and uncover the pool. The motor, roll member and 
extension device are all mounted to a downwardly extending slide tract; 
and a winch is mounted at the bottom of the pool for drawing the assembly 
downwardly to the bottom for storage. The roll member and rods are hollow 
and sealed at their rends to provide sufficient buoyancy to allow the 
apparatus to rise to the surface when it is to be extended.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, a rectangular swimming pool 11 is shown, having end 
walls 13 and 15 and side walls 17 and 19. As shown also in FIG. 2, the 
automatic cover mechanism is mounted to the deepest end wall 13. It 
includes a slide track 21 that extends vertically from the water level 
when full, to a point near the bottom. Slide track 21 is mounted to wall 
13 and has a slot (not shown) that runs along its length. 
An electrical motor 23 has a rear bracket 25, FIG. 3, secured to it that 
slidably fits within the slot on slide track 21. Two output shafts 27 
extend from the motor 23, one on each side. The output shafts 27 rotate in 
unison with each other. A threaded rod or screw 29 extends laterally from 
each output shaft 27. One of the screws 29 contains clockwise or right 
hand threads, while the other contains counterclockwise or left hand 
threads. Screws 29 are positioned in a horizontal plane and parallel with 
end wall 13. One screw 29 extends from the motor 23 to a point near side 
wall 17, while the other extends from motor 17 to a point near side wall 
19. Screws 29 are of equal length and are coaxial with each other. A gear 
or sprocket 31 is mounted to the outer end of each screw 29. 
A cylindrical roll member 33 (FIG. 1), is mounted above the screws and 
parallel with them. Roll member 33 is hollow and sealed at its ends. Roll 
member 33 extends substantially across the pool width and has gears 35 on 
its ends that rotate with the roll member. Gears 35 mesh with gears 31 and 
are driven by them. A bracket 37 on each end extends from the screws 29 to 
the roll member 33 for supporting the roll member. A guide 39 is located 
on each wall 17 and 19 adjacent the ends of the roll member 33 and screws 
29. Brackets 37 slidably engage the guides 39 to stabilize the roll member 
33 and screws 29. 
A cover or sheet of material 41 of dimensions sufficient to cover the pool 
is adapted to be rolled onto and off the roll member 33. Sheet 41 is a 
flexible, tough material, preferably laminated vinyl reinforced with a 
tightly woven mesh. It is in the shape of the pool, in the illustrated 
embodiment rectangular, with an inner end secured to the roll member 33. 
The outer end is adapted to extend to the opposite end wall 15. A 
stiffener or brace 43 is secured to the outer end and extends 
substantially from side wall 17 to side wall 19. Drain holes 42 are 
provided in sheet 41. 
An extension means for moving the outer end of the sheet toward the 
opposite end 15, as the motor 23 unwinds the roll, is secured between 
screws 29 and brace 43. It is a scissor type device made up of a plurality 
of rods pivotally interlinked in a criss-cross fashion. As shown in FIG. 
1, a thread follower or sleeve 45 is carried on each screw 29. Sleeve 45 
has internal threads, thus moves linearly along screw 29 while the screw 
rotates and the sleeve is restrained from rotation. Since the screws 29 
are threaded in reverse to each other and are rotated in the same 
direction, the sleeves 45 will either linearly approach each other, or 
move away from each other, depending on the direction of rotation. 
The free ends of a first pair of rods 47 are secured by articulated 
connections to the sleeves 45. A second pair of rods 47 is pivotally 
secured at one of their ends to the first pair of rods 47. The second 
pair's other ends are pivotally secured to a third or last pair of rods 
47. As many pairs are employed as necessary the length of the pool. The 
free ends of the last pair of rods 47 are slidably carried by the brace 
43. All of the rods 47 are the same length. The rods 47 and the brace 43, 
preferably, are sealed so as to provide buoyancy. Within each pair, each 
rod is pivotally mounted to its other pair by a connection at mid center, 
indicated as 49. Each rod 47 within a pair crosses its other pair so that 
one end of each rod will be nearer side wall 17 and the other end nearer 
side wall 19. 
Moving the sleeves 45 together causes the rods 47 to extend their total 
length, as shown on FIG. 1. Moving the sleeves 45 apart shortens the total 
length, as shown in FIG. 4. Screws 29 and motor 23 serves as means to move 
the free ends apart and toward each other. The pitch of the threads on 
screws 29, and the size of gears 31 and 35 are correlated so that the 
sheet will unwind and wind up at the same rate that the extension device 
moves the brace 43. An overrunning clutch could be utilized to avoid 
placing the rods 47 in a bind should speeds differ. 
The apparatus also includes submersion means for submerging the entire 
assembly into the pool when retracted. This gets the apparatus out of the 
way. The submersion apparatus includes the slide track 21 and a winch 
mounted at the bottom of the pool below the slide track. The winch has an 
electrical motor and gear reducer 51 which drives a pulley 53. A cable 55 
is fastened to the screw motor 23 and is wrapped around pulley 53. 
Solenoid circuitry (not shown) engages and disengages pulley 53 from its 
motor 51. The motor 51 friction is sufficient to maintain the assembly in 
a submerged state when pulley 53 is in engagement. 
In operation, to cover the pool, initially the assembly will be restrained 
at the bottom of the pool by the winch. The solenoid is then actuated to 
release pulley 53 from winch motor 51. The buoyancy of roll member 33 and 
rods 47 causes the assembly to rise to the surface. Motor 23 will begin 
rotating screws 29 and roll member 33 through gears 31 and 35. This 
rotation in the unwinding direction causes the sheet 41 to unwind from the 
roll member 33. At the same time, threaded sleeves 45 begin moving toward 
each other, thus extending the overall length of the extension device and 
causing brace 43 to move toward the opposite pool end 15. When the sheet 
is fully extended, the motor 23 stops. 
To uncover the pool, motor 23 rotates in the reverse direction, winding 
sheet 41 back onto roll member 33. Threaded sleeves 45 begin moving apart 
from each other, thus shortening the length of the extension device. When 
fully retracted, winch motor 51 is actuated to draw the assembly to a 
point near the bottom, as shown in FIG. 4. 
In the specific embodiment described hereinbefore the roll member has been 
disclosed to serve as an accumulation means for accumulating the flexible 
sheet, since it does so with a minimum amount of trapped air. Other 
accumulation means can be employed if desired. For example, the 
accumulation means may comprise a progressive gathering of the sheet. The 
gathering is made easier where the sheet has pre-fold lines to facilitate 
accordioning into a compact, gathered accumulation. Also, the scissor type 
extension device has been disclosed to serve as the extension means. Other 
extension means can be employed. For example, linear metallic members such 
as bands of arcuate cross section can be unrolled or fluid, such as air or 
water, can be pumped into inflatable, unrolling channels to extend the 
outer end of the flexible sheet. 
In this area of technology, even a partial covering of the surface of the 
water in a pool is beneficial. Consequently even a rectangular cover is 
beneficial in oddly shaped pools. On the other hand, the cover in 
accordance with this invention can be shaped to afford maximum coverage. 
For example, the flexible sheet can be in other shapes, such as fan 
shaped. 
While the pool cover assembly of this invention can be stored submerged at 
any location; such as sides or ends of the pool, the usual least obtrusive 
submerged storage is adjacent the deep end where diving is usually done 
and the bottom end of the pool is seldom used by swimmers. 
It should be apparent that an invention having significant advantages has 
been provided. The cover apparatus requires no tracks to be laid. The 
entire assembly is located inside the pool to avoid any accidental 
stumbling over it. 
Although this invention has been discribed with a certain degree of 
particularity, it is understood that the present disclosure has been made 
only by way of example and that numerous changes in the details of 
construction and the combination and arrangement of parts may be resorted 
to without departing from the spirit or the scope of this invention.