AUSTRALIA Patents Act ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Application Number: 20072 Lodgement Date: 6 th August 2007 Nominated Patentee: Sunbather Pty Ltd Invention Title: Pool Cover Control The following statement is a full description of this invention, including the best method of performing it known to the applicant.
POOL COVER CONTROL This invention relates to improvements in retractable swimming pool covers. Background to the invention 5 One popular type of swimming pool cover uses an arrangement of buoyant slats that can be stored on a drum and rolled out to cover the pool surface. The drum generally lies below the surface of the pool and the buoyant cover is partially supported by the water and partly guided by the edges of the pool. A cover of this sort is disclosed in USA patents 2001/0034906 and 2002/0046817. One problem 10 with this type of pool cover is damage to the cover and drive mechanism due to incorrect water level in the pool. It is an object of this invention to provide a water level control system for pool covers so that accidental damage can be avoided. 15 Brief description of the invention To this end the present invention provides a control system for a pool which incorporates a buoyant pool cover in which the control system includes a water level probe at a pool full level and a probe at position where the water level is too low to support the cover the activation of the upper level probe deactivates the 20 cover drive mechanism and if necessary actuates the draining of the pool to an acceptable level and the activation of the lower probe deactivates the cover drive mechanism and actuates the filling of the pool to an acceptable level. The provision of a cut off switch to prevent movement of the cover that may cause damage is insufficient to solve the problem. It is necessary to integrate the control 25 system to the pool filling and draining system usually a pump and/or a solenoid valve. Prior art systems failed to take this step. Usually the pool cover is stored underwater, in a compartment at one end of the pool. There is a feed slot across the width of the pool through which the cover is fed or retracted. The normal water level of the pool needs to be between the top 30 beam which is usually level with the edge of the pool wall and the top of the compartment wall so that the cover can float over the compartment wall. If the water level is too high the cover is retarded by the top beam.
2 Preferably the control system and the level probes are disposed in the compartment to reduce the interference caused by wave action in the pool. Detailed description of the invention A preferred embodiment of the invention will be described with reference to the 5 drawings in which: Figure 1 is a schematic cross section of the cover compartment incorporating the control system of this invention; Figure 2 is a plan view of the system of figure 1; Figure 3 is a circuit diagram of the control system of this invention. 10 In the embodiment illustrated the pool incorporates an end compartment 10 defined by the pool floor 11 the end wall 12 the dividing wall 13 and the beam 15 which defines a space with the end wall 12 for the cover drive motor 21 above the water level of the pool. 15 The recommended water level 17 is about mid way of the slot 19 defined by the beam 15 and the dividing wall 13 The bouyant pool cover 30 may be of the general type described in USA patents 2001/0034906 and 2002/0046817 and is stored on a roller 31 in compartment 10. The roller 31 is driven by a chain or belt, driven from sprocket 23 of the cover 20 motor 21. The drive motor 21 is supported above the compartment 10 by brackets 22. The top of the compartment may be covered for safety and aesthetic reasons. Attached to the motor 21 is a probe unit 25 with a water level sensor 26 aligned with the maximum water level 18 permissible in the pool and probe 27 is aligned with 25 lowest water level 16 permissible in the pool. If the water level is too low the cover cannot clear the dividing wall 13 and is likely to bunch up within compartment 10. If the probe 27 is activated the motor cannot be activated and the control system activates a pump or solenoid valve to raise the water level to the prescribed level 17. 30 If the water level is too high the cover 30 is likely to be impeded by the beam 15 and again bunch up within compartment 10. Activation of the probe 26 will shut the motor down and allow time for the pool to drain through an overflow pipe, or alternatively the actuation of the probe will actuate a pump to drain the pool so 3 that the level returns to the prescribed level 17. The trip lever 29 will be actuated by the cover if the water level approaches the maximum level 18 and this also shuts down the motor 21. The control circuit for the system is shown in figure 3. 5 The pool cover motor uses a power supply 32 and is operated by the local switch 33 or the remote switch 34. The system is controlled by the programmable interface controllers 36 and 37. The pool cover motor drive may be positioned inside the roller shaft or at either end of the roller shaft. The motor may be any conventional type such as an electric motor or an hydraulic motor and may be 10 submerged . The probe 25 may be of the type that relies on conductivity of the water. A ground lead 28 is continuously immersed. When the lower probe 27 is out of the water, no current passes and the low level LED indicator 40 is illuminated. This state triggers the limit switch 38 shut down the motor circuit 21 and triggers the pool fill 15 solenoid 43 or a separate pump to fill the pool. When the upper probe is immersed in water current passes and illuminates flood LED 41 this is the trigger for limit switch 39 to shut down the motor circuit and open the drain circuit to lower the pool level. The LED indicator 42 illuminates during filling. If the trip lever 29 is actuated the proximity switch 45 switches off the cover motor. 20 The water level probes 25 and 27 and the trip lever 29 may be located together or separately at any part of the pool and do not need to be in the motor drive compartment but may be in the roller storage pit or in the pool itself. From the above it can be seen that the present invention has over come the problem of varying water levels damaging the pool cover. Those skilled in the art 25 will realize that other embodiments of the invention are possible without departing from the core teachings of the invention.