Title:
SWIMMING POOL COVER
United States Patent 3747132
Abstract:
A flexible pool cover is stored in rolled condition on a reel at one end of a swimming pool. Cables extend along the pool sides and over a reversing pulley for attachment to a trolley secured to the free cover end. The cable reels and cover reel are driven at the same rotational rate. Means are provided for maintaining the cover and the cables free of substantial slack throughout reeling and unreeling movement.
US Patent References:
Safety cover for swimming pools
Karobonik et al. - July 1956 - 2754899
Safety swimming pool cover
McGuire - August 1959 - 2898607
Swimming pool safety device
Shook et al. - November 1960 - 2958083
Retractable swimming pool cover
Karasiewicz - February 1962 - 3019450
Extendible and retractable cover apparatus for swimming pools
Lamb - August 1962 - 3050743
Safety cover for swimming pools
Karobonik et al. - July 1956 - 2754899
Safety swimming pool cover
McGuire - August 1959 - 2898607
Swimming pool safety device
Shook et al. - November 1960 - 2958083
Retractable swimming pool cover
Karasiewicz - February 1962 - 3019450
Extendible and retractable cover apparatus for swimming pools
Lamb - August 1962 - 3050743
Application Number:
05/252580
Publication Date:
07/24/1973
Filing Date:
05/12/1972
View Patent Images:
Export Citation:
Primary Class:
Other Classes:
160/310
International Classes:
E04H4/10; E04H4/00; E04H3/16; E04H3/18
Field of Search:
4/172,172.14,172.13,172.12,172.11 160/26,37,268,310
US Patent References:
Primary Examiner:
Artis, Henry K.
Claims:
I claim
1. A swimming pool cover of the type comprising a reel having a cover spooled thereon; means operatively connected to the cover for spooling and unspooling the same across a swimming pool and including a reel having thereon spoolable cable means operatively connected to the cover and means for simultaneously rotatably driving the cover and cable reels; the improvement wherein the spooling and unspooling means includes
2. The swimming pool cover of claim 1 wherein the resilient means comprises the cable means.
3. The swimming pool cover of claim 1 wherein the resilient means consists essentially of the cable means.
4. The swimming pool cover of claim 1 wherein the differential travel between the cable means and the cover lies in the range of 1-8 feet.
5. The swimming pool cover of claim 1 wherein the resilient means comprises cable takeup means.
6. The swimming pool cover of claim 5 wherein the cable takeup means comprises a resiliently biased takeup reel between the cable means and the cover.
7. The swimming pool cover of claim 1 wherein the resilient means comprises means allowing differential rotation of the cable reel and the cover reel.
8. The swimming pool cover of claim 7 comprising means mounting the cable reel for free rotation about an axis and the resilient means comprises a spring drivably interconnecting the driving means and the cable reel.
9. The swimming pool cover of claim 8 wherein the spring comprises a spiral spring.
10. A swimming pool cover of the type comprising a reel having an impermeable cover spooled thereon; means operatively connected to the cover for spooling and unspooling the same across a swimming pool and including a trolley for traversing the pool, means for moving the trolley and attachment means connecting the trolley to the cover; the cover defining a path of movement along the surface of water in the swimming pool and then upwardly adjacent the edge of the pool, the trolley being above the water surface; the improvement comprising
1. A swimming pool cover of the type comprising a reel having a cover spooled thereon; means operatively connected to the cover for spooling and unspooling the same across a swimming pool and including a reel having thereon spoolable cable means operatively connected to the cover and means for simultaneously rotatably driving the cover and cable reels; the improvement wherein the spooling and unspooling means includes
2. The swimming pool cover of claim 1 wherein the resilient means comprises the cable means.
3. The swimming pool cover of claim 1 wherein the resilient means consists essentially of the cable means.
4. The swimming pool cover of claim 1 wherein the differential travel between the cable means and the cover lies in the range of 1-8 feet.
5. The swimming pool cover of claim 1 wherein the resilient means comprises cable takeup means.
6. The swimming pool cover of claim 5 wherein the cable takeup means comprises a resiliently biased takeup reel between the cable means and the cover.
7. The swimming pool cover of claim 1 wherein the resilient means comprises means allowing differential rotation of the cable reel and the cover reel.
8. The swimming pool cover of claim 7 comprising means mounting the cable reel for free rotation about an axis and the resilient means comprises a spring drivably interconnecting the driving means and the cable reel.
9. The swimming pool cover of claim 8 wherein the spring comprises a spiral spring.
10. A swimming pool cover of the type comprising a reel having an impermeable cover spooled thereon; means operatively connected to the cover for spooling and unspooling the same across a swimming pool and including a trolley for traversing the pool, means for moving the trolley and attachment means connecting the trolley to the cover; the cover defining a path of movement along the surface of water in the swimming pool and then upwardly adjacent the edge of the pool, the trolley being above the water surface; the improvement comprising
Description:
BACKGROUND OF THE INVENTION
Swimming pool covers which are advanced and retracted by motor operated mechanisms are well known in the prior art. One typical type swimming pool cover involves a spooled cover adjacent one end of the pool, a reversing pulley at the other end of the pool, and suitable cables passed over the reversing pulley and connected at opposite ends to the driving mechanism and the cover. Typical disclosures of this type are found in U. S. Pat. Nos. 2,754,899; 2,958,083; 3,277,498 and 3,426,366. In the typical device of this type, the cable reels and the cover reel are driven simultaneously, either by being mounted on the same shaft or by connection through single ratio gearing.
There is a substantial problem with simple drives of this type which is a result of the changing diameter of the cover reel and the cable reels. It will be apparent to those skilled in the art that, at the beginning of cover placement, the cover reel is of larger diameter than the cable reels and the diameter of the cover reel decreases while the diameter of the cable reels increases. When beginning the placement of the swimming pool cover, one revolution of the cover reel pays out a length of cover equal to the circumference of the cover reel while the cable reels retract a length of cable equal to the circumference of the cable reels. Since the cover reel is of substantially larger diameter than the cable reels, the pool cover becomes slack and tends to wind up on the roller in the wrong direction when it should in fact be unwinding.
Accordingly, the devices of the prior art present a substantial disadvantage at the beginning of cover placement. Since the diameters of the cover and cable reels approach each other during cover placement, the amount of slack in the cover increases until the diameters of the cover reel and the cable reels are substantially equal. Since the cable reels are increasing in diameter, the amount of slack in the cover decreases in proportion to the number of revolutions made by the cover and cable reels after their diameters are substantially equal. It will be apparent that all of the slack may be taken out of the cover and, upon subsequent rotation of the cable and cover reels, the cover is placed substantially in tension. This also has its disadvantages since the cover material may be subject to stretching. It will be apparent that some care must be exercised in the design of the prior art pool covers to avoid over-tensioning the cover.
It will also be apparent to those skilled in the art that, at the beginning of cover retraction, the cover reel is of smaller diameter than the cable reels and the diameter of the cover reel increases while the diameter of the cable reels decrease. At the outset of cover retraction, one revolution of the cover reel spools a length of material equal to the cover reel diameter while one revolution of the cable reels pays out a length of cable equivalent to the circumference of the cable reel. Since the cable reel is of greater diameter than the cover reel at this point in time, the cable goes slack and tends to wind up on the reel in the wrong direction when it should be unwinding. The cable continues to slacken until the diameters of the cable reel and the cover reel are the same at which time the cable begins to tighten.
The prior art has recognized this disadvantage as evidenced by U. S. Pat. Nos. 3,019,450 and 3,050,743. In these disclosures, clutches are provided for the cable reels so that the cable drum is permitted to rotate freely in the unwinding direction as the cover reel is being driven. Similarly, a one-way clutch is provided for the cover reel so that the cover reel is permitted to rotate freely in the unwinding direction as the cable reel is being driven in the winding direction. While this is a satisfactory technical solution to the problem, it will be appreciated that considerable expense is entailed in the provision of the one-way clutches both in initial cost and in maintenance.
The device of this invention allows the incorporation of an extremely simple drive mechanism for the cover and cable reels while maintaining the cover and cable free of substantial slack.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a motorized swimming pool cover including means for maintaining the cover free of substantial slack throughout spooling and unspooling movement thereof.
Another object of the invention is to provide a mechanized swimming pool cover in which the cover and cable reels are simultaneously driven and including resilient means operatively disposed between the driving mechanism and the cover for allowing differential travel between the cable means and the cover.
In summary, the swimming pool cover of this invention comprises a reel having a cover spooled thereon; means operatively connected to the cover for spooling and unspooling the same across a swimming pool and including a reel having thereon spoolable cable means operatively connected to the cover and means for simultaneously rotatably driving the cover and cable reels; the improvement wherein the spooling and unspooling means includes means for maintaining the cover and the cable means free of substantial slack adjacent the respective reel thereof throughout spooling and unspooling movement, the maintaining means including resilient means in driving connection between the driving means and the cover for allowing differential travel between the cable means and the cover.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of one embodiment of the invention;
FIG. 2 is an enlarged cross sectional view of the trolley which moves alongside the pool during cover placement and retraction and is taken along line 2--2 of FIG. 1 as viewed in the direction indicated by the arrows;
FIG. 3 is a cross sectonnal view through the cable reels and the cover reel illustrating another embodiment of the invention;
FIG. 4 is a partial plan view of one end of the trolley of another embodiment of the invention; and
FIG. 5 is a cross sectional view of the embodiment of FIG. 4, taken along line 5--5 thereof as viewed in the direction indicated by the arrows.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Attention is directed to FIG. 1 wherein there is illustrated a swimming pool 10 containing a quantity of water 12. A motorized swimming pool cover 14 constituting this invention is illustrated as substantially covering the pool 10. The swimming pool cover 14 comprises as major components a sheet or cover 16, a roller 18 constituting a reel for the sheet 16, means 20 for unspooling the sheet 16 including cable reels 22, 24 having cable means 26, 28 spooled therearound and driving means 30 for driving the roller 18 and the cable reels 22, 24.
The sheet or cover 16 may be of any suitable material such as polyethylene and is wrapped or spooled about the roller 18. As will be apparent from FIG. 1, the sheet 16 is paid out and retracted from adjacent the top of the roller 18. It is well known that leaves and other debris collect on the sheet 16. Since the sheet 16 is reeled onto the top of the roller 18, leaves or debris on the sheet 16 pass over the top of the roll and onto the ground adjacent thereto. The pool owner is thus faced with the rather minor task of cleaning up the pool edge adjacent the roll 18. If the sheet 16 were taken up along the bottom of the roll 18, leaves and debris would be trapped in the spirally wound sheet 16 thereby tending to puncture the same.
The roller 18 may conveniently be a piece of aluminum tubing mounted by suitable ball bearings or the like (not shown) on a stationary shaft 32 mounted on opposite ends thereof by suitable brackets 34. The brackets 34 are stationary and may be affixed to the walkway surrounding the pool 10 in any suitable manner.
The unspooling means 20 includes a trolley 36 comprised of an I-beam or other structural member 38 spanning the pool 10. The opposite ends of the I-beam 38 are affixed to suitable dollies 40 having wheels 42 thereon for traversing the pool 10. The cables 26, 28 are disposed on opposite sides of the pool 10 and extend respectively from the reels 22, 24 under suitable idler pulleys 44 through suitable ring guides 46 (FIG. 2) and around stationary reversing pulleys 48 for connection to the I-beam 38 in any suitable manner.
The cable reels 22, 24 may be constructed in any suitable manner. Conveniently, the hub of the reels 22, 24 may comprise the roller 18 while the reel flanges 50, 52 respectively may comprise annular disks affixed to the roller 18. In order to drive the roller 18 and reels 22, 24, one of the reel flanges 52 may be grooved to receive an endless belt 54.
The driving means 30 includes the endless belt 54 and a driving sheave 56 operatively connected to a gear box 58 which is driven by a suitable electric motor 60 in a conventional manner. The motor 60 is preferably a reversing motor controlled by a three-way switch 62. The switch 62 allows covering and uncovering of the pool 10 as well as a neutral position as will be apparent to those skilled in the art.
When the motor 60 is energized to uncover the pool 10, the diameter of the cover spool is substantially less than the diameter of the cable reels 22, 24. Accordingly, the cables 26, 28 pay off cable more rapidly than the sheet 16 is wound onto the roller 18. The cables 26, 28 accordingly tend to wind in the wrong direction about the reels 22, 24 rather than unwind. Basically, the same problem occurs with the sheet 16 when it is in the process of being placed over the pool 10.
To overcome this disadvantage and still provide an extremely simple drive mechanism for the roller 18 and reels 22, 24, the cables 26, 28 are, in accordance with one embodiment of this invention, selected from a known group of resilient tensile force transmitting means. This group is known in the boating arts as "shock cord" and is normally used instead of rope to fasten boat fixtures where some elasticity is desired or required. Shock cord is commercially available through most boating supply stores and is commonly constructed of elastic rubber strands with a woven sleeve or overlay of nylon. One manufacturer of shock cord is N. A. Taylor, Inc., of Waxahachie, Texas. The diameter of the shock cord may vary widely depending on the length of the pool, the elasticity required, and the weight of the sheet 16. As might be expected, the diameter of a typical shock cord decreases significantly during stretching. A typical shOck cord elongates approximately 30 per cent when placed under about 100 pounds tension. Substantial elasticity is required in the normal pool installation since the differential travel of the cables 26, 28 with respect to the sheet 16 is in the range of 1-8 feet and typically is about 6 feet.
By utilizing a typical shock cord for the cables 26, 28, there is sufficient elasticity in the cable means to allow spooling and unspooling of the sheet 16 without creating substantial slack in either the cables 26, 28 or the sheet 16. Accordingly, the practice of this invention allows an extremely simple drive arrangement wherein the cable reels 22, 24 and the roll 18 are driven simultaneously and yet avoids the creation of substantial slack in either the sheet 16 or the cables 26, 28.
Referring to FIG. 3, there is illustrated another embodiment of the invention. FIG. 3 comprises a longitudinal cross sectional view through the cover roll and the cable reels as will be more fully apparent hereinafter. FIG. 3 illustrates a motorized swimmIng pool cover 64 having a sheet or cover 66 spirally wound about a roller 68. The roller 68 is mounted by suitable ball bearings 70 for rotation about a stationary shaft 72 which is supported at opposite ends thereof by suitable brackets (not shown). Axial movement of the roll 68 is precluded by suitable thrust plates 74 which are affixed to the stationary shaft 72 in any suitable manner.
Comprising a part of a driving means similar to that illustrated in FIG. 1 is a sheave 76 which is affixed to the roller 68 in any suitable fashion. As is illustrated in FIG. 3, the sheave 76 not only acts to drive the roller 68 but also bears against the thrust plate 74. It will accordingly be seen that the roller 68 is directly driven by the sheave 76 in a 1:1 ratio.
There is also provided a pair of cable reels 78, 80 which are driven simultaneously with the roller 68 but which do not necessarily rotate at the same velocity. The reels 78, 80 are generally S-shaped in cross section and comprise radiating plates 82, 84, 86 and 88, 90, 92 respectively. Hubs 94, 96 define, with the walls 84, 86 and 88, 90 respectively, a pair of cable receiving areas as in a conventional reel. Circumferential plates 98, 100 define, with the walls 82, 84 and 90, 92 respectively, a pair of spring housings incorporated in the reels 78, 80. The reels 78, 80 are mounted for rotation about the roller 68 by housing and spool bearings 102, 104, 106, 108. Suitable thrust collars 110, 112 are affixed to the roller 68 and prevent inward movement of the reels 78, 80 respectively. Outward movement of the reel 78 is precluded by a thrust collar 114 acting between the thrust plate 74 and the housing bearing 102. Outward movement of the reel 80 is prevented by the housing bearing 106 abutting the sheave 76.
Disposed in the spring housing of each of the reels 78, 80 is a spirally wound spring 116, 118 having one end thereof affixed to the roll 68 and the other end thereof affixed to the circumferential plate 98, 100 respectively.
Suitable cables 120, 122 are operatively connected to the reels 78, 80 and are connected to a suitable trolley as in the embodiment of FIG. 1 for spooling and unspooling the cover 66 across a swimming pool. It will be apparent that the elasticity afforded by the springs 116, 118 operates in much the same manner as the resilient cable means 26, 28 of FIG. 1 to prevent excessive slack developing in the cover 66 and the cables 120, 122 during covering and uncovering of the swimming pool.
As is apparent from the relative amount of spooled cable 120, 122 and spooled cover 66, FIG. 3 illustrates the situation where the cover 66 is placed over the swimming pool. When the sheave 76 is driven in the cover spooling direction, the length of the cable 120, 122 paid out is greater than the length of cover 66 spooled onto the roller 68. Thus, the cable 120, 122 becomes slack and tends to wind up in the wrong direction. The springs 116, 188 accordingly elongate and retard rotation of the reels 78, 80 and retard payout of the cable 120, 122 to maintain the same reasonably taut. Continued spooling of the cover 66 creates additional slack in the cables 120, 122, which is accommodated by further elongation of the springs 116, 118. As the diameter of the spooled cover 66 passes that of the reeled cable 120, 122, the length of the cover 66 spooled per revolution is greater than the length of cable 120, 122 paid out from the reels 78, 80. The cables 120, 122 accordingly begin to tighten and thereby compress the springs 116, 118 to pay out additional length of the cable 120, 122.
At the start of cover pay out, the diameter of the spooled cover 66 exceeds that of the reeled cable 120, 122 causing excessively rapid cover pay out. As a result, the cover 66 becomes slack. The springs 116, 118 begin to expand thereby taking up additional lengths of cable to move the trolley (not shown) an additional incremental length and thereby take the slack out of the cover 66. Until the diameter of the spooled cover 66 equals the diameter of the reeled cable, cover pay out is relatively too fast tending to induce slack in the cover. The springs 116, 118 continue to expand thereby taking up additional or incremental cable lengths to move the trolley slightly faster and take the slack out of the cover 66. As the cover 66 approaches the end of its unspooling travel, the diameter of the spooled cover is less than the diameter of the reeled cable such that cover pay out is relatively too slow. Since cover pay out is relatively too slow, the tension in the cables 120, 122 increases thereby compressing the springs 116, 118 effectively allowing additional pay out of cable 120, 122.
Referring now to FIGS. 4 and 5, there is illustrated another embodiment of the invention. FIGS. 4 and 5 illustrate a trolley 124 comprising an I-beam or other structural member 126 spanning a swimming pool. The trolley 124 includes a dolly 128 on each side thereof having wheels 130 enabling the trolley 124 to traverse the length of the pool. Affixed to the web of the I-beam 126 is a mounting plate 132 carrying a stationary stub shaft 134. A thrust plate 136 is affixed to the end of the stub shaft 134 and captivates thereon a take-up reel 138. The take-up reel is substantially identical to the reels 78, 80 and includes a cable receiving area 140 and a spring housing 142 mounted together for rotation about the stub shaft 134 by bearings 144, 146. A spiral spring 148 is positioned in the spring housing 142 and has one end affixed to the stub shaft 134 and the other end affixed to the cable housing 142. A cable 150 is spooled onto a driving reel of the type shown in FIG. 1 and passes around a reversing pulley, also as shown in FIG. 1, and is then attached to the take-up reel 138. The tension in the cable 150 is controlled by how tightly the spring 148 is wound.
To provide a comparison of the embodiments of this invention, the following table is provided: ##SPC1##
The inspection of the foregoing summary will illustrate that the resilient components of the various embodiments of this invention undergo a cyclical lenthening and shortening. It should be apparent that, for example at the start of cover pay out with the embodiment of FIG. 1, the cables 26, 28 should be stretched to allow shortening during the initial portion of cover pay out. Similarly, the springs 116, 118 of the embodiment of FIG. 3 should be compressed to a significant extent in order to take up cable during the initial portion of cover pay out.
Another important feature of the invention resides in the provision of a plurality of attachments 152 (FIG. 1) and 154 (FIG. 4) between the I-beams 38, 126 and the respective covers. Using FIG. 1 as exemplary, the attachments 152 comprise the force transmitting connection between the I-beam 38 and the cover 16. When the I-beam 38 is moving away from the roller 18, the attachments 152 are in tension to pull the cover 16 off the roller 18. When the I-beam 38 is moving toward the roller 18, the attachments 152 are in tension and the sheet 16 is pulling the trolley 36.
One substantial difficulty with swimming pool covers occurs after a substantial rainfall. Since the cover 16 is desirably impermeable, rainfall accumulates thereon. Using a 20 feet × 40 feet swimming pool as exemplary, a 2 inch rainfall accumulation weighs approximately 8,300 pounds. Initial retraction of the cover 16 is not a substantial problem since the cover 16 slides through the water. A substantial problem exists at the termination of cover retraction. Since the trolley 36 and the roller 18 are above the water level, the cover 16 assumes an upwardly concave configuration when the trolley 36 approaches the roller 18. Under this circumstance, the cover 16 would have to be vertically lifted to completely retract the same. Even if only 10 percent of the accumulated rainfall remains on the cover 16, the weight to be lifted by the roller 18 is so substantial as to prevent complete retraction of the cover 16.
To overcome this difficulty, the attachments 152 are selected of a predetermined length of flexible materials. The minimum length of the stretched attachments 152 is the distance from the I-beam 38 where the attachments 152 are secured and the water 12, so that the cover 16 does not assume an upwardly concave configuration when loaded with rainwater. The maximum length of the unstretched attachments 152 is the distance from the I-beam 38 where the attachments 152 are secured to a point above the water 12 to avoid dipping the leading edge of the cover 16 into the water when the cover 16 is not loaded with rainwater. In the typical pool installation, this length of the unstretched attachments 152 is between 4-10 inches. In a prototype constructed in accordance with the invention, the optimum length of the unstretchable attachments 152 proved to be 5 inches.
Although the attachments 152 may be made of any flexible material meeting the above criteria, they conveniently are the same material as the cables 26, 28.
Swimming pool covers which are advanced and retracted by motor operated mechanisms are well known in the prior art. One typical type swimming pool cover involves a spooled cover adjacent one end of the pool, a reversing pulley at the other end of the pool, and suitable cables passed over the reversing pulley and connected at opposite ends to the driving mechanism and the cover. Typical disclosures of this type are found in U. S. Pat. Nos. 2,754,899; 2,958,083; 3,277,498 and 3,426,366. In the typical device of this type, the cable reels and the cover reel are driven simultaneously, either by being mounted on the same shaft or by connection through single ratio gearing.
There is a substantial problem with simple drives of this type which is a result of the changing diameter of the cover reel and the cable reels. It will be apparent to those skilled in the art that, at the beginning of cover placement, the cover reel is of larger diameter than the cable reels and the diameter of the cover reel decreases while the diameter of the cable reels increases. When beginning the placement of the swimming pool cover, one revolution of the cover reel pays out a length of cover equal to the circumference of the cover reel while the cable reels retract a length of cable equal to the circumference of the cable reels. Since the cover reel is of substantially larger diameter than the cable reels, the pool cover becomes slack and tends to wind up on the roller in the wrong direction when it should in fact be unwinding.
Accordingly, the devices of the prior art present a substantial disadvantage at the beginning of cover placement. Since the diameters of the cover and cable reels approach each other during cover placement, the amount of slack in the cover increases until the diameters of the cover reel and the cable reels are substantially equal. Since the cable reels are increasing in diameter, the amount of slack in the cover decreases in proportion to the number of revolutions made by the cover and cable reels after their diameters are substantially equal. It will be apparent that all of the slack may be taken out of the cover and, upon subsequent rotation of the cable and cover reels, the cover is placed substantially in tension. This also has its disadvantages since the cover material may be subject to stretching. It will be apparent that some care must be exercised in the design of the prior art pool covers to avoid over-tensioning the cover.
It will also be apparent to those skilled in the art that, at the beginning of cover retraction, the cover reel is of smaller diameter than the cable reels and the diameter of the cover reel increases while the diameter of the cable reels decrease. At the outset of cover retraction, one revolution of the cover reel spools a length of material equal to the cover reel diameter while one revolution of the cable reels pays out a length of cable equivalent to the circumference of the cable reel. Since the cable reel is of greater diameter than the cover reel at this point in time, the cable goes slack and tends to wind up on the reel in the wrong direction when it should be unwinding. The cable continues to slacken until the diameters of the cable reel and the cover reel are the same at which time the cable begins to tighten.
The prior art has recognized this disadvantage as evidenced by U. S. Pat. Nos. 3,019,450 and 3,050,743. In these disclosures, clutches are provided for the cable reels so that the cable drum is permitted to rotate freely in the unwinding direction as the cover reel is being driven. Similarly, a one-way clutch is provided for the cover reel so that the cover reel is permitted to rotate freely in the unwinding direction as the cable reel is being driven in the winding direction. While this is a satisfactory technical solution to the problem, it will be appreciated that considerable expense is entailed in the provision of the one-way clutches both in initial cost and in maintenance.
The device of this invention allows the incorporation of an extremely simple drive mechanism for the cover and cable reels while maintaining the cover and cable free of substantial slack.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a motorized swimming pool cover including means for maintaining the cover free of substantial slack throughout spooling and unspooling movement thereof.
Another object of the invention is to provide a mechanized swimming pool cover in which the cover and cable reels are simultaneously driven and including resilient means operatively disposed between the driving mechanism and the cover for allowing differential travel between the cable means and the cover.
In summary, the swimming pool cover of this invention comprises a reel having a cover spooled thereon; means operatively connected to the cover for spooling and unspooling the same across a swimming pool and including a reel having thereon spoolable cable means operatively connected to the cover and means for simultaneously rotatably driving the cover and cable reels; the improvement wherein the spooling and unspooling means includes means for maintaining the cover and the cable means free of substantial slack adjacent the respective reel thereof throughout spooling and unspooling movement, the maintaining means including resilient means in driving connection between the driving means and the cover for allowing differential travel between the cable means and the cover.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of one embodiment of the invention;
FIG. 2 is an enlarged cross sectional view of the trolley which moves alongside the pool during cover placement and retraction and is taken along line 2--2 of FIG. 1 as viewed in the direction indicated by the arrows;
FIG. 3 is a cross sectonnal view through the cable reels and the cover reel illustrating another embodiment of the invention;
FIG. 4 is a partial plan view of one end of the trolley of another embodiment of the invention; and
FIG. 5 is a cross sectional view of the embodiment of FIG. 4, taken along line 5--5 thereof as viewed in the direction indicated by the arrows.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Attention is directed to FIG. 1 wherein there is illustrated a swimming pool 10 containing a quantity of water 12. A motorized swimming pool cover 14 constituting this invention is illustrated as substantially covering the pool 10. The swimming pool cover 14 comprises as major components a sheet or cover 16, a roller 18 constituting a reel for the sheet 16, means 20 for unspooling the sheet 16 including cable reels 22, 24 having cable means 26, 28 spooled therearound and driving means 30 for driving the roller 18 and the cable reels 22, 24.
The sheet or cover 16 may be of any suitable material such as polyethylene and is wrapped or spooled about the roller 18. As will be apparent from FIG. 1, the sheet 16 is paid out and retracted from adjacent the top of the roller 18. It is well known that leaves and other debris collect on the sheet 16. Since the sheet 16 is reeled onto the top of the roller 18, leaves or debris on the sheet 16 pass over the top of the roll and onto the ground adjacent thereto. The pool owner is thus faced with the rather minor task of cleaning up the pool edge adjacent the roll 18. If the sheet 16 were taken up along the bottom of the roll 18, leaves and debris would be trapped in the spirally wound sheet 16 thereby tending to puncture the same.
The roller 18 may conveniently be a piece of aluminum tubing mounted by suitable ball bearings or the like (not shown) on a stationary shaft 32 mounted on opposite ends thereof by suitable brackets 34. The brackets 34 are stationary and may be affixed to the walkway surrounding the pool 10 in any suitable manner.
The unspooling means 20 includes a trolley 36 comprised of an I-beam or other structural member 38 spanning the pool 10. The opposite ends of the I-beam 38 are affixed to suitable dollies 40 having wheels 42 thereon for traversing the pool 10. The cables 26, 28 are disposed on opposite sides of the pool 10 and extend respectively from the reels 22, 24 under suitable idler pulleys 44 through suitable ring guides 46 (FIG. 2) and around stationary reversing pulleys 48 for connection to the I-beam 38 in any suitable manner.
The cable reels 22, 24 may be constructed in any suitable manner. Conveniently, the hub of the reels 22, 24 may comprise the roller 18 while the reel flanges 50, 52 respectively may comprise annular disks affixed to the roller 18. In order to drive the roller 18 and reels 22, 24, one of the reel flanges 52 may be grooved to receive an endless belt 54.
The driving means 30 includes the endless belt 54 and a driving sheave 56 operatively connected to a gear box 58 which is driven by a suitable electric motor 60 in a conventional manner. The motor 60 is preferably a reversing motor controlled by a three-way switch 62. The switch 62 allows covering and uncovering of the pool 10 as well as a neutral position as will be apparent to those skilled in the art.
When the motor 60 is energized to uncover the pool 10, the diameter of the cover spool is substantially less than the diameter of the cable reels 22, 24. Accordingly, the cables 26, 28 pay off cable more rapidly than the sheet 16 is wound onto the roller 18. The cables 26, 28 accordingly tend to wind in the wrong direction about the reels 22, 24 rather than unwind. Basically, the same problem occurs with the sheet 16 when it is in the process of being placed over the pool 10.
To overcome this disadvantage and still provide an extremely simple drive mechanism for the roller 18 and reels 22, 24, the cables 26, 28 are, in accordance with one embodiment of this invention, selected from a known group of resilient tensile force transmitting means. This group is known in the boating arts as "shock cord" and is normally used instead of rope to fasten boat fixtures where some elasticity is desired or required. Shock cord is commercially available through most boating supply stores and is commonly constructed of elastic rubber strands with a woven sleeve or overlay of nylon. One manufacturer of shock cord is N. A. Taylor, Inc., of Waxahachie, Texas. The diameter of the shock cord may vary widely depending on the length of the pool, the elasticity required, and the weight of the sheet 16. As might be expected, the diameter of a typical shock cord decreases significantly during stretching. A typical shOck cord elongates approximately 30 per cent when placed under about 100 pounds tension. Substantial elasticity is required in the normal pool installation since the differential travel of the cables 26, 28 with respect to the sheet 16 is in the range of 1-8 feet and typically is about 6 feet.
By utilizing a typical shock cord for the cables 26, 28, there is sufficient elasticity in the cable means to allow spooling and unspooling of the sheet 16 without creating substantial slack in either the cables 26, 28 or the sheet 16. Accordingly, the practice of this invention allows an extremely simple drive arrangement wherein the cable reels 22, 24 and the roll 18 are driven simultaneously and yet avoids the creation of substantial slack in either the sheet 16 or the cables 26, 28.
Referring to FIG. 3, there is illustrated another embodiment of the invention. FIG. 3 comprises a longitudinal cross sectional view through the cover roll and the cable reels as will be more fully apparent hereinafter. FIG. 3 illustrates a motorized swimmIng pool cover 64 having a sheet or cover 66 spirally wound about a roller 68. The roller 68 is mounted by suitable ball bearings 70 for rotation about a stationary shaft 72 which is supported at opposite ends thereof by suitable brackets (not shown). Axial movement of the roll 68 is precluded by suitable thrust plates 74 which are affixed to the stationary shaft 72 in any suitable manner.
Comprising a part of a driving means similar to that illustrated in FIG. 1 is a sheave 76 which is affixed to the roller 68 in any suitable fashion. As is illustrated in FIG. 3, the sheave 76 not only acts to drive the roller 68 but also bears against the thrust plate 74. It will accordingly be seen that the roller 68 is directly driven by the sheave 76 in a 1:1 ratio.
There is also provided a pair of cable reels 78, 80 which are driven simultaneously with the roller 68 but which do not necessarily rotate at the same velocity. The reels 78, 80 are generally S-shaped in cross section and comprise radiating plates 82, 84, 86 and 88, 90, 92 respectively. Hubs 94, 96 define, with the walls 84, 86 and 88, 90 respectively, a pair of cable receiving areas as in a conventional reel. Circumferential plates 98, 100 define, with the walls 82, 84 and 90, 92 respectively, a pair of spring housings incorporated in the reels 78, 80. The reels 78, 80 are mounted for rotation about the roller 68 by housing and spool bearings 102, 104, 106, 108. Suitable thrust collars 110, 112 are affixed to the roller 68 and prevent inward movement of the reels 78, 80 respectively. Outward movement of the reel 78 is precluded by a thrust collar 114 acting between the thrust plate 74 and the housing bearing 102. Outward movement of the reel 80 is prevented by the housing bearing 106 abutting the sheave 76.
Disposed in the spring housing of each of the reels 78, 80 is a spirally wound spring 116, 118 having one end thereof affixed to the roll 68 and the other end thereof affixed to the circumferential plate 98, 100 respectively.
Suitable cables 120, 122 are operatively connected to the reels 78, 80 and are connected to a suitable trolley as in the embodiment of FIG. 1 for spooling and unspooling the cover 66 across a swimming pool. It will be apparent that the elasticity afforded by the springs 116, 118 operates in much the same manner as the resilient cable means 26, 28 of FIG. 1 to prevent excessive slack developing in the cover 66 and the cables 120, 122 during covering and uncovering of the swimming pool.
As is apparent from the relative amount of spooled cable 120, 122 and spooled cover 66, FIG. 3 illustrates the situation where the cover 66 is placed over the swimming pool. When the sheave 76 is driven in the cover spooling direction, the length of the cable 120, 122 paid out is greater than the length of cover 66 spooled onto the roller 68. Thus, the cable 120, 122 becomes slack and tends to wind up in the wrong direction. The springs 116, 188 accordingly elongate and retard rotation of the reels 78, 80 and retard payout of the cable 120, 122 to maintain the same reasonably taut. Continued spooling of the cover 66 creates additional slack in the cables 120, 122, which is accommodated by further elongation of the springs 116, 118. As the diameter of the spooled cover 66 passes that of the reeled cable 120, 122, the length of the cover 66 spooled per revolution is greater than the length of cable 120, 122 paid out from the reels 78, 80. The cables 120, 122 accordingly begin to tighten and thereby compress the springs 116, 118 to pay out additional length of the cable 120, 122.
At the start of cover pay out, the diameter of the spooled cover 66 exceeds that of the reeled cable 120, 122 causing excessively rapid cover pay out. As a result, the cover 66 becomes slack. The springs 116, 118 begin to expand thereby taking up additional lengths of cable to move the trolley (not shown) an additional incremental length and thereby take the slack out of the cover 66. Until the diameter of the spooled cover 66 equals the diameter of the reeled cable, cover pay out is relatively too fast tending to induce slack in the cover. The springs 116, 118 continue to expand thereby taking up additional or incremental cable lengths to move the trolley slightly faster and take the slack out of the cover 66. As the cover 66 approaches the end of its unspooling travel, the diameter of the spooled cover is less than the diameter of the reeled cable such that cover pay out is relatively too slow. Since cover pay out is relatively too slow, the tension in the cables 120, 122 increases thereby compressing the springs 116, 118 effectively allowing additional pay out of cable 120, 122.
Referring now to FIGS. 4 and 5, there is illustrated another embodiment of the invention. FIGS. 4 and 5 illustrate a trolley 124 comprising an I-beam or other structural member 126 spanning a swimming pool. The trolley 124 includes a dolly 128 on each side thereof having wheels 130 enabling the trolley 124 to traverse the length of the pool. Affixed to the web of the I-beam 126 is a mounting plate 132 carrying a stationary stub shaft 134. A thrust plate 136 is affixed to the end of the stub shaft 134 and captivates thereon a take-up reel 138. The take-up reel is substantially identical to the reels 78, 80 and includes a cable receiving area 140 and a spring housing 142 mounted together for rotation about the stub shaft 134 by bearings 144, 146. A spiral spring 148 is positioned in the spring housing 142 and has one end affixed to the stub shaft 134 and the other end affixed to the cable housing 142. A cable 150 is spooled onto a driving reel of the type shown in FIG. 1 and passes around a reversing pulley, also as shown in FIG. 1, and is then attached to the take-up reel 138. The tension in the cable 150 is controlled by how tightly the spring 148 is wound.
To provide a comparison of the embodiments of this invention, the following table is provided: ##SPC1##
The inspection of the foregoing summary will illustrate that the resilient components of the various embodiments of this invention undergo a cyclical lenthening and shortening. It should be apparent that, for example at the start of cover pay out with the embodiment of FIG. 1, the cables 26, 28 should be stretched to allow shortening during the initial portion of cover pay out. Similarly, the springs 116, 118 of the embodiment of FIG. 3 should be compressed to a significant extent in order to take up cable during the initial portion of cover pay out.
Another important feature of the invention resides in the provision of a plurality of attachments 152 (FIG. 1) and 154 (FIG. 4) between the I-beams 38, 126 and the respective covers. Using FIG. 1 as exemplary, the attachments 152 comprise the force transmitting connection between the I-beam 38 and the cover 16. When the I-beam 38 is moving away from the roller 18, the attachments 152 are in tension to pull the cover 16 off the roller 18. When the I-beam 38 is moving toward the roller 18, the attachments 152 are in tension and the sheet 16 is pulling the trolley 36.
One substantial difficulty with swimming pool covers occurs after a substantial rainfall. Since the cover 16 is desirably impermeable, rainfall accumulates thereon. Using a 20 feet × 40 feet swimming pool as exemplary, a 2 inch rainfall accumulation weighs approximately 8,300 pounds. Initial retraction of the cover 16 is not a substantial problem since the cover 16 slides through the water. A substantial problem exists at the termination of cover retraction. Since the trolley 36 and the roller 18 are above the water level, the cover 16 assumes an upwardly concave configuration when the trolley 36 approaches the roller 18. Under this circumstance, the cover 16 would have to be vertically lifted to completely retract the same. Even if only 10 percent of the accumulated rainfall remains on the cover 16, the weight to be lifted by the roller 18 is so substantial as to prevent complete retraction of the cover 16.
To overcome this difficulty, the attachments 152 are selected of a predetermined length of flexible materials. The minimum length of the stretched attachments 152 is the distance from the I-beam 38 where the attachments 152 are secured and the water 12, so that the cover 16 does not assume an upwardly concave configuration when loaded with rainwater. The maximum length of the unstretched attachments 152 is the distance from the I-beam 38 where the attachments 152 are secured to a point above the water 12 to avoid dipping the leading edge of the cover 16 into the water when the cover 16 is not loaded with rainwater. In the typical pool installation, this length of the unstretched attachments 152 is between 4-10 inches. In a prototype constructed in accordance with the invention, the optimum length of the unstretchable attachments 152 proved to be 5 inches.
Although the attachments 152 may be made of any flexible material meeting the above criteria, they conveniently are the same material as the cables 26, 28.