Flexible or portable closure – partition – or panel – Plural strip – slat – or panel type – Roll type
Reexamination Certificate
2001-04-10
2004-12-07
Johnson, Blair M. (Department: 3634)
Flexible or portable closure, partition, or panel
Plural strip, slat, or panel type
Roll type
C160S311000
Reexamination Certificate
active
06827120
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to certain new and useful improvements in automatic swimming pool cover system and, more particularly, to a cover system using a hydraulic drive for slatted buoyant type pool covers.
2. Brief Description of Related Art
Pool covers are used on many swimming pools. They save energy, keep the pool clean, minimize chemical use and provide desirable safety features. In fact, in windy locations, a pool cover is essential for maintaining pool water at comfortable temperatures at a reasonable expense.
The types of commercially available pool covering systems and those which have been proposed include free floating covers, tie down/stretched covers and track anchored floating covers. Mechanisms for retracting such covers back and forth across a pool include purely manual devices such as the “Rocky's” roller manufactured B. C. Leisure Ltd. 113-1305 Welch Street North Vancouver B.C. Canada V7P 1B3; semi-automatic systems (see U.S. Pat. No. 4,351,072) and automatic systems, which are usually electrically or hydraulically powered. (See U.S. Pat. Nos. 2,754,899; 2,958,083; 3,019,450; 3,050,743; 3,613,126; 3,982,286; 4,939,798 and 5,327,590).
Automatic swimming pool cover systems can include a flexible vinyl fabric sized so that most of it floats on the surface of the pool water. The pool water acts as a low friction surface significantly reducing the amount of force required to move the cover across the pool. The front edge of the cover is secured to a rigid boom spanning the width of the pool for holding the front edge of the cover above the water as it is drawn back and forth across the pool.
To draw the cover across the pool, a cable, typically a Dacron line, is incorporated into and forms a beaded tape which is sewn or attached to the side edges of the pool cover. The beaded tape in turn is captured and slides within a “C” channel of an extruded aluminum track. The track is secured either to the pool deck or to the underside of an overhanging coping along the sides of the swimming pool. The cables extending from the beaded tape sections of the cover are trained around pulleys at the distal ends of the tracks and return in a parallel “C” channel to the drive mechanism where they wind around cable take-up reels.
To uncover the pool, the drive mechanism rotates a cover drum mounted at one end of the pool winding the pool cover around its periphery and unwinding the cables from around the take-up reels. To cover the pool the drive mechanism rotatably drives the cable take-up reels, winding up the cables to pull the cover across the pool while unwinding the cover from around the cover drum.
The present applicant recognized the problems inherent in the use of an electric drive system for operating pool covers. Aside from the numerous safety factors, the electric motors had to be completely insulated from the water environment. Nevertheless, many pool cover drives are located in a subterranean environment. Consequently, the overall costs of construction and costs of installation were considerable. Notwithstanding, even rain water and ground water tended to collect in subterranean compartments housing the electric motors and their associated electrical components. In fact, it has been recognized that at least fifty percent of the failures of most automatic pool cover systems is due to the inherent problem of water damage.
In order to overcome this problem, the present applicant had proposed and provided, as hereinafter described, pool cover systems which rely totally upon a hydraulic drive located at or near the swimming pool. An electric drive could be provided to operate a pump for pumping the hydraulic fluid. However, an electric drive and the pump could be located at a remote location and even housed in a building or the like.
In U.S. Pat. No. 5,184,357 issued Feb. 9, 1993, the present applicant describes automatic swimming pool cover systems wherein a first hydraulic drive provides torque for resisting cover drum rotation during cover extension and for rotating the cover drum for cover retraction. A separate and second hydraulic drive provides torque for rotating the cable reels for cover extension and for resisting cable reel rotation during cover retraction. In this latter U.S. Pat. No. 5,184,357, the desirability of having positive stops located at the respective ends of the pool is taught. These positive stops will stop movement of the rigid leading edge carrying the pool cover by increasing tension load on the cover and cables sufficiently for counter-balancing the torque of the particular driving hydraulic motor which is rotating either the cable reels or cover drum. These mechanisms need only be able to mechanically withstand the differential load of the driving hydraulic motor which rotates the cover drum and the opposing tension load imposed by the pumping hydraulic motor resisting rotation of the cover drum.
In under track systems (where the track is fastened to the underside of overhanging copings), the copings or walls at the respective ends of the pool can function as inherent stops arresting cover extension or retraction, provided however, that the rigid leading edge appropriately engages the coping or walls. Also, return pulleys at the distal ends of the respective tracks which carry the returning cables to the take-up reels, provide inherent positive stops for arresting extension of the cover. The pulley housings do not have “C” channels and hence will stop the sliders sliding within the “C” channels supporting the rigid leading edge carrying the cover across the pool. [See U.S. Pat. No. 4,939,798 issued Jul. 10, 1990 to applicant, Harry J. Last, entitled: “LEADING EDGE AND TRACK SLIDER SYSTEM FOR AN AUTOMATIC SWIMMING POLL COVER” and U.S. Pat. No. 4,466,144 issued Aug. 21, 1984 to Joe H. Lamb entitled: “PULLEY ASSEMBLY FOR SWIMMING POOL COVER”].
Automatic pool cover systems utilizing interconnected rigid buoyant slats which roll up on a submerged or elevated drum as described by U.S. Pat. No. 3,613,126, to R. Granderath, are popular in Europe. These pool cover systems utilize passive forces arising from buoyancy or gravity for propelling, the cover to extend the cover across a pool. With either buoyancy or gravity, there must be some mechanism to prevent a retracted cover from unwinding responsive to the passive force. Such passive force systems also have a disadvantage in that the passive force must be overcome during retraction. Granderath suggests a worm gear drive mechanism for winding the cover and preventing cover drum rotation when not powered. The slats for these are further described in U.S. Pat. No. 4,577,352, to Gautheron.
U.S. Pat. No. 4,411,031 to Stolar describes a system similar to Granderath where instead of rigid hinged buoyant slats, various floating sheet materials such as a polyethylene polybubble, or a laminate of vinyl sheeting and foamed substrate, are floated on the surface of the water. The propulsion of the cover across the pool is reliant on buoyant and gravitational forces much like the system in the Granderath patent.
Pool covers which employ floating slats or like materials, and which use buoyant forces to propel the cover across the pool, necessarily wind the cover onto a roller drum which is positioned below the water surface. When the cover is fully retracted from the swimming pool surface and fully wound onto the cover drum, the upper extremity of the complete cover and drum are at least two inches below the surface of the water cover in the pool. In some cases, the cover and drum are located in a separate water filled niche next to the pool. In other instances the cover and drum may be located near the bottom of the pool, or in a special hidden compartment underneath the pool floor to aesthetically hide the cover and roller drum, but also so that the mechanism does not interfere with swimmers.
Buoyant covers, which rely on buoyant or gravitational force to propel the cover across the pool, need to move at a low linear speed, and accordi
Johnson Blair M.
Schaap Robert J.
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