Abstract:
An apparatus operable in a wet environment, for controlling the flow of electrical current to an electrical load, adapted to be coupled to an AC source for supplying an AC signal. Includes as switching device coupled to the electrical load, the switching device being operative in either a first state wherein significant current flow through the load is prevented or a second state wherein current flow through the load is substantially undisturbed. An interconnection means is adapted to be coupled to an AC source and electrical load, wherein the interconnection means allows for plug and receptacle connection to the AC source and electrical load, respectively. Also includes a low air pressure receiver switch for receiving user input signals from a pneumatic transmitter to determine the operating status of the switching device. A controller receives user signals coupled through the low air pressure receiver and provides for switching the switching device between its first and second states in a predetermined sequence. A power supply is adapted to be coupled to the AC source for supplying an AC potential, low voltage, direct current to the controller. Includes an isolation means for electrically isolating the user input signals from the AC source, wherein the isolation means includes pneumatic coupling between the pneumatic transmitter and low air pressure receiver.

Description:
RELATED APPLICATIONS  
       [0001]    The applicant claims priority of provisional application No. 60/274225, filed Mar. 9, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to an apparatus used for the control of electrical loads of a bathing appliance. More particularly, the present invention relates to a controller coupled to a low air pressure switch input means, a switching device coupled to a source of A.C. voltage for controlling electrical pumps and loads of a bathing appliance, for use in a wet, electrically hazardous environment.  
         BACKGROUND OF THE INVENTION  
         [0003]    Bathing appliances such as hot tubs, swimming pools, shower units and hydromassage bath fixtures employ a means to control the flow of electrical energy to pump motors, air blower, heaters, lights and other loads, associated with their use. The prior art means of providing this control may be very simple, for example a wall mounted switch or mechanical timer may be utilised to control the flow of electrical power enabling the circulation pump to be turned on and off.  
           [0004]    Regardless of the means employed for this control function, it is of primary importance to ensure that there is no possibility of the bather, touching an electrically live switching or control means. Those readers skilled in the art will realise that there is a high likelihood of electrical shock hazard when a source of A.C. mains power is accessible to a bather submersed in essentially, conductive, grounded water. The prior art utilises many means of providing electrical, mechanical or a combination of both insulation systems to prevent shock hazard. For example, a simple wall switch or mechanical timer may be mounted a sufficient distance away from the bather. This will necessitate the bather stepping out of the bath water, to activate the control to start or stop the pump, or other electrical load.  
           [0005]    One common type of prior art control system, utilises a pneumatic isolation means for allowing the bather to remain in the bath water and control the pump load. In this type of system, a water proof, actuation “air bellows” style of button is mounted on the rim of the subject bathing appliance, accessible to the bather. A length of air hose is connected to the bellows, with the opposite end connected to an air pressure activated switch. The switch means of sufficient ampacity is series coupled between the pump motor or other electrical load of the bathing appliance and a source of AC mains supply. When the subject bather operates the “air bellows switch”, air pressure is coupled through the hose to the switch, causing it to operate. The switch will toggle between conducting and non-conducting states on alternate operations of the air bellows, opening or closing the source of AC mains supply to the load. Such systems have been installed for many years and provide a useful, low cost means of operating the bath while immersed in the bathing water.  
           [0006]    Prior art control systems are also known to utilise electrical isolation means for controlling the electrical loads of the bath appliance. In this type of system an electrical push button, touch pad or similar electrical actuator means is mounted on the rim of the bath appliance. The button is coupled to a controller means by conductive cable. The controller means is coupled to a source of AC mains supply through a step-down, isolation transformer. The controller means is also coupled to a switching means, which is coupled in series between the AC mains supply and the electrical load of the bathing appliance. The combination of coupling the controller means to the step down transformer and switching means, provides sufficient electrical isolation to allow an electrical switching means to be made accessible to the user of the bathing appliance. When ever the button means is activated by the bather, the controller means signals the switching means which will toggle between conducting and non-conducting states on alternate operations, opening or closing the source of AC mains supply to the load. This type of electrical isolation, control system may provide additional functions that are difficult to implement in the pneumatic control means described above. For example, the controller means could provide timing signals to the switching means, thereby allowing the electrical load to operate for a given period of time. Similarly, the switching means could include a thyristor means and receive phase angle control signals from the controller means, by way of the user button means. Such an implementation could for example, provide variable speed function to universal motor loads, or light dimming control of bathing appliances so equipped. A further advantage of a wired coupled button means, is that status lights, water temperature and programmable timer displays may be added without difficulty. A person skilled in the art will be familiar with thyristors, phase angle control, universal motors and advanced displays, included in such a system.  
           [0007]    A drawback with pneumatic control devices is that they are difficult to design with sufficient control features such as variable speed functions or user displays. For this reason, pneumatic controls are typified as “low quality” and are delegated to inexpensive products at the “introductory sales end” of a manufacturers market.  
           [0008]    While electrically isolated control systems provide sufficient features, they require the use of electrical cables between the AC mains supply, electrical load(s) and between the button and controller means. Although this is the accepted installation provided in the prior art, it would be a desirable feature to eliminate these wiring connections. Wire connections require skilled electricians to provide proper and safe installation. Further, once installed, the wire cables used to provide the installation are often located in areas where access is difficult, making future servicing a costly problem. Additionally, step down, isolation transformers and other electrical isolation means utilised within these controls increase the size and cost of the control system.  
           [0009]    Accordingly, it is an object of the present invention to provide a control system used in electrically hazardous environments, for the operation of electrical loads used in bathing appliances such as hot tubs, swimming pools, shower units and hydromassage bath fixtures, wherein the control system requires no specialised skills for installation, enabling homeowners or those persons, not necessarily skilled in electrically wiring, to be able to install and service the controller system.  
           [0010]    It is a further object of the present invention to couple a momentary contact, low air pressure switch to a controller means allowing for the enhanced control features such as timers and phase angle voltage supply of the connected load.  
           [0011]    One preferred embodiment of the present invention contemplates an integrated, low air pressure switch, comprising a conductive snap dome installed on the shared circuit traces of the controller wiring assembly. Such an arrangement may be utilised to provide signalling and electrical isolation means, suitable for use in an electrically hazardous environment as earlier explained.  
           [0012]    A person skilled in the art would understand that such an arrangement of controller means, low air pressure switches and simplified installation of electrical controls provides for increased functionality from prior air switch controls, without incurring the complexity and cost of step-down transformers and other electrical isolation systems used in “high end” controls. Furthermore, there are other means of assembling such components into a control system suitable for use in the end system application, without departing from the scope of the present invention.  
         SUMMARY OF THE INVENTION  
         [0013]    To protect the bather from electric shock, the electrical energy driving the controller means and electrical load is sufficiently isolated from the bather user control by use of a telemetry signal.  
           [0014]    According to an aspect of the invention, there is provided an apparatus operable in a wet environment for operating an electrical load adapted to be coupled to an AC source for supplying and AC signal comprising:  
           [0015]    an interconnection means adapted to be coupled to an AC source and electrical load, wherein the interconnection means allows for plug and receptacle connection to the AC source and electrical load, respectively;  
           [0016]    a switching device adapted to be coupled in series with the interconnection means, wherein the switching device is operable in either a first state wherein significant current flow through the electrical load is prevented or a second state wherein current flow through the electrical load is substantially undisturbed;  
           [0017]    a switch input means for receiving user input signals to determine the operating status of the switching device and coupled electrical load;  
           [0018]    a controller means for receiving the switch input status signals and for switching the switching device between is first and second states in a predetermined sequence;  
           [0019]    a power supply means, coupled to the AC source for supplying an A.C. line potential, low voltage, direct current to the controller means;  
           [0020]    isolation means for electrically isolating the user controls from the AC source, wherein the isolation means includes a low air pressure actuator coupled to the switch input means.  
           [0021]    According to another aspect of the invention, there is further provided an method for operating an electrical load adapted to be coupled to an AC source for supplying and AC signal, operable in a wet environment, comprising:  
           [0022]    an interconnection means adapted to be coupled to an AC source and electrical load, wherein the interconnection means allows for plug and receptacle connection to the AC source and electrical load, respectively;  
           [0023]    a switching device adapted to be coupled in series with the interconnection means, wherein the switching device is operable in either a first state wherein significant current flow through the electrical load is prevented or a second state wherein current flow through the electrical load is substantially undisturbed;  
           [0024]    a switch input means for receiving user input signals to determine the operating status of the switching device and coupled electrical load;  
           [0025]    a controller means for receiving the switch input status signals and for switching the switching device between is first and second states in a predetermined sequence;  
           [0026]    a power supply means, coupled to the AC source for supplying A.C. line potential, low voltage, direct current to the controller and radio receiver means;  
           [0027]    isolation means for electrically isolating the user controls from the AC source, wherein the isolation means includes a low air pressure actuator coupled to the switch input means. the method comprising the steps of:  
           [0028]    (a) switching the switching device to its first state;  
           [0029]    (b) waiting for a telemetry data;  
           [0030]    (c) detecting zero crossing point of AC input signal;  
           [0031]    (d) generating a delay; and  
           [0032]    (e) switching the switching device to its second state.  
           [0033]    Other advantages, objects and features of the present invention will be readily apparent to those skilled in the art from a review of the following detailed description of the preferred embodiment in conjunction with the accompanying drawings and claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]    The embodiments of the invention will now be described with reference to the accompanying drawings, in which:  
         [0035]    [0035]FIG. 1 is a schematic of the prior art showing a cut-away view of a typical hydromassage bathing appliance, detailing the installation of a pneumatically controlled switch and water circulation pump;  
         [0036]    [0036]FIG. 2 is a schematic of the prior art showing a cut-away view of a typical hydromassage bathing appliance, detailing the installation of an electrically isolated control system coupled to a water circulation pump;  
         [0037]    [0037]FIG. 3 is a schematic of one embodiment of the present invention;  
         [0038]    [0038]FIG. 4 is one embodiment of the present invention, detailing a side-section view of the low air pressure receiver and input switch signalling means, including a top view of the printed circuit board conductors for clarifying the drawing; and  
         [0039]    [0039]FIG. 5 is a flow chart illustrating the receiving of user input signals and control of switching device sequence of the controller of the present invention. 
     
    
       [0040]    With respect to the above drawings, similar references are used in different Figures to denote similar components.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0041]    Referring to FIG. 1, there is shown an embodiment of a prior art pneumatically coupled user actuator and switch. A typical hydromassage bathing appliance  40  is shown being filled with water  60  to a typical operating level  50 . The water drain  65  is assumed to be closed. The bath  40  sits of a flooring platform  55 . An electrical load in the form of a water pump and motor assembly  25  and circulation plumbing  45  completes the bath assembly. An AC source  10  is series coupled to a pneumatically controlled switch  15  which in turn, supplies power  20  to pump and motor assembly  25 . A user control “air bellows switch”  35  is connected to one end of hose  30 , the other end of hose  30  being coupled to pneumatic air switch  15 . When bather presses air bellows switch  35 , air is pressurised in hose  30  and activates pneumatic switch  15 , which changes state, closing the switch and connecting AC source  10  to pump and motor assembly  25 . Similarly, pressing air bellows switch  35  a second time will cause switch  15  to change state disconnecting AC source  10  from pump and motor assembly  25 , causing water to stop circulating in bath  40 . Supplying a sufficient length of hose  30  with ambient room air, provides a sufficient electrical isolation barrier for the bather immersed in bath water  50  to the AC source  10 .  
         [0042]    A drawback with this arrangement of pneumatic control device, is that they are difficult to design with sufficient control features such as variable speed functions or user displays. In order to improve the features of such pneumatic controls, more sophisticated devices have been developed which shall now be described.  
         [0043]    Referring now to FIG. 2, there is shown a second embodiment of a prior art electrically isolated control system  70 , adapted to be coupled to a bathing appliance of similar construction to that detailed in FIG. 1, above. An AC source  10  is series coupled to one side of relay switch  85 . The other side of relay switch  85  is coupled to pump and motor assembly  25  through cable  20 . AC source  10  is also coupled to stepdown, isolation transformer  75 , providing low-voltage, isolated power to controller means  80 . A user electrical push button  90  is mounted to bathing appliance  40  in such a manner that a user immersed in bath water  50  could activate switch  90 . Switch  90  is coupled to controller means  80  via wire cable assembly  95 . Activating control switch  90  sends a user input signal to controller means  80  through cable  95 , causing controller  80  to activate relay coil  86 . Activation of relay coil  86  causes relay switch  85  to close, thus connecting AC source  10  to pump and motor assembly  25  through power cable  20 . Electrical shock hazard protection of a user immersed in bath water  50  is provided by special construction methods of step-down, isolation transformer  75  and relay unit (comprising  85  and  86 ). A reader skilled in the art will understand electrical isolation means as applied to transformers, relays and similar components.  
         [0044]    Drawbacks to electrically isolated control systems include:  
         [0045]    (a) the use of electrical cables between the AC mains supply, electrical load(s);  
         [0046]    (b) the use of signal interface cables between the button and controller means;  
         [0047]    (c) difficult to access cables and control units after installation; and  
         [0048]    (d) the requirements of isolation transformer and other electrical isolation means to protect the user from electric shock, increasing costs of such control devices.  
         [0049]    Now referring to FIG. 3, there is shown an embodiment of the present invention  100 . There are numerous advantages of the present invention  100  in that it does not require persons skilled in the art to install it, there are no power or interface cables necessary for interconnection and it is not necessary to provide electrical isolation between the control system  100  and the bather due to the use of pneumatic isolation through the interconnection of user air pressure bellows  35 , air hose  30  and air pressure receiver switch  135 . A person skilled in the art will recognise that such an arrangement provides a means of status signalling to the controller means by virtue of the momentary contact switch incorporated within the air pressure receiver unit.  
         [0050]    Such an arrangement is known in the prior art. However, the herein invention contemplates incorporating a “snap dome” and integral plastic molding configuration to optimise the design for low cost and small size.  
         [0051]    The present invention  100  also includes an interconnection means (comprising  110  and  115 ) that are adapted to allow AC source  10  to be coupled to input connector set  110  and likewise, electrical load power supply cord  145  to be coupled to output connector set  115 . A person skilled in the art will recognise that interconnection means  110  and  115  comprise a NEMA (National Electrical Manufacturers Association) power plug assembly for connection to AC supply sources in North America, with a nominal voltage of 120 Volts AC and nominal current rating of 15 Amperes. For higher voltages, currents or other parts of the World, alternate interconnection means could be adapted to those requirements without deviating from the scope of the present invention.  
         [0052]    A switching device  120  is adapted to be coupled in series with the input connector set  110  and the output connector set  115 . In the preferred embodiment shown in FIG. 3, the switching device  120  is a triac, although a person skilled in the art would realise that any switching device, such as a relay or other thyristor arrangement, could be substituted without departing from the scope of the present invention. A series resistor  125  is coupled to the input connector set  110  in such a manner that a when controller  100  is connected to an AC source  10 , one side of resistor  125  becomes energised. The opposite side of resistor  125  is coupled to controller means  130  in such a manner as to provide an AC line potential, low-voltage power supply circuit to operate the logic devices of controller means  130 . A person skilled in the art would realise that a step-down transformer, capacitor or other means could be substituted for resistor  125 , although the preferred embodiment shown provides for very low cost. Controller means  130  is coupled to switching device  120  in such a manner as to allow controller means  130  to operate the switching device in either a first state wherein significant current flow through the electrical load  25  is substantially prevented or a second state wherein current flow through the electrical load is substantially undisturbed.  
         [0053]    A reader skilled in the art will recognise that the coupling of the controller means  130  to the AC source  10 , as described above, would create a shock hazard should the low-voltage circuits be accessible. It is therefore clear that low air pressure receiver  135  provides both signaling and electrical isolation means and is a key component in the implementation of the herein invention.  
         [0054]    Prior to operation, the control system  100  is connected to AC source  10 , using interconnection means  110 . Electrical load example  25  is connected to interconnection means  115  using power cord  150  and plug  145 . Additionally, air hose  30  is connected to the bath mounted air bellows “sender”  35  and the low air pressure receiver switch assembly  135 . This completes the installation of control system  100  and allows safe and reliable installation of electrical loads within the current carrying capacity of the control system  100 .  
         [0055]    During operation, controller means  130  monitors the status of momentary switch contained within the low air pressure receiver assembly  135 . The switch will close each time the user presses the air bellows “sender”  35 , causing pressurised air to travel through hose  30 . Air bellows “sender”  35  and hose  30  will not be further discussed as a reader skilled in the art will be familiar with such devices.  
         [0056]    Controller means  130  executes control sequence outlined in FIG. 4 and determines which state switching device  120  should be in, allowing electrical load  25  to either remain at standby or be operative.  
         [0057]    Referring now to FIG. 4, there is shown one embodiment of the low air pressure receiver/momentary contact switch unit, herein referred to as the air switch. Readers skilled in the art will realise that numerous configurations of momentary contact air switches are available in the art. The unique feature of the present invention is derived from a unique “conductive snap dome” and integration system. While it is possible to utilise prior art momentary contact air switches as a component of the contemplated control system, such an assembly would not be fully integrated, thus adding unnecessary costs. A review of FIG. 4 will indicate that many of the component parts of the air switch  135  are already inherent in other necessary parts of the complete system:  
         [0058]    The air switch  135  comprises a series of sub-component parts which when assembled as outlined, form a sub-system comprising:  
         [0059]    (a) a low air pressure receiver for activating a membrane in synchronisation with an externally connected air switch sender bellows;  
         [0060]    (b) a momentary contact electrical switch of low power rating; and  
         [0061]    (c) a electrical isolation system consisting of the pneumatic column and flexible, dielectric membrane  170 .  
         [0062]    In addition, the sub-components comprising the air switch device may utilise shared components which must be inherent within a given control system. For example, the air pressure receiver chamber  160  many not be a separate part but is simply a “chamber” or feature molded in the chassis of the of the overall control system. A reader skilled in the art will be able to recognise components of the air switch  135  which may share features and functions with already existing components in the end system control. A through understanding of the air switch will be gained by a review of each specific sub-component, as follows:  
         [0063]    The air switch  135  comprises several sub-components which may be fabricated as an individual part in itself or as a part of an overall assembly, comprising shared sub-components such as the air chamber  160 , discussed above. To simplify the review of air switch  135 , it shall be considered a single component part, preferably constructed utilising a molded plastic air receiver chamber  160  with integral hose connection barb  164 . When air at a low pressure is routed to hose barb  164 , it enters into the receiver air chamber  162 . The molded component air receiver chamber  160 , forms an air tight seal by virtue of compression of “o” ring  165  with membrane film  170 . The structure comprising the chamber  160 , “o” ring  165  and film  170  are in turn placed over snap dome device  175  which rests in contact with circular PCB trace  185 . PCB substrate  180  forming a rear cover for chamber  160 . When the above components are placed in compression, pressurised air in chamber area  162  will be compressed in relation to “ambient” air pressure  167 . This will cause film material  170  to flex against snap dome  175 , causing it to also flex towards PCB trace  195 , completing a circuit between PCB traces  185  and  195 .  
         [0064]    Electrical connections can be suitably made to PCB traces  185  and  195  by associated “flow through” connections to the traces, such as outlined at  190 . It is also understood that PCB “flow through”  190  provides a means of releasing air under snap dome  175  to ambient air  167 .  
         [0065]    Snap dome  175  is preferably constructed of a conductive material which possesses high electrical conductivity to complete the switch circuit and provide a mechanical spring mechanism to flex back to a “switch open” state when air pressure in chamber area  162  approximately equals ambient air pressure  167 .  
         [0066]    It is further possible to fabricate snap dome  175  of such materials, thickness and overall area to set the working air pressure in chamber area  162  to match the specifications of many different air pressure bellows that may be connected through hose barb  164 .  
         [0067]    Referring now to FIG. 5, a flow chart of the operating mode sequence  200  of controller  130  is shown. When control system  100  is connected to AC mains supply  10 , entry to operating mode sequence  200  is started. Controller  130  executes step TURN OFF TRIAC  210  placing triac  120  in a first state wherein significant current flow through the electrical load is prevented. Controller  130  then advances to step WAIT FOR START COMMAND  220 . If no start command is received, controller  130  will loop back to step TURN OFF TRIAC  210  until a start command is received. When a start command is received, controller advances to step TURN ON TRIAC AT SELECTED PHASE ANGLE  230 . A reader skilled in the art will recognise that this step involves the creation of a phase angle delay based on the zero crossing reference of the AC mains  10  developed across resistor  125  as outlined in FIG. 3 above. Where the switching device  120  is a relay, the phase angle delay will be approximately 0 electrical degrees. Where the switching device is a triac as shown in the preferred embodiment, FIG. 3, the phase angle delay may be any value within a suitable range for operating the connected electrical load  25 .  
         [0068]    Once triac is turned on in step  230 , the controller  130  will advance to step IS SPEED COMMAND SELECTED?  240 . For control systems  130  that have no speed requirements, step  240  and  250  will be skipped. For control systems  130  that are equipped to operate using phase angle delay control for adjusting speed or effective voltage to the connected load  25 , a loop in control sequence  200  is formed. If a speed command has not been selected, controller  130  advances to step IS STOP COMMAND SELECTED?  260 . If no stop command is selected, controller  130  advances to step TURN ON TRIAC AT SELECTED PHASE ANGLE  230  and the RUNNING LOOP  232  is continued. If the stop command is selected at step  260 , the controller advances to step TURN OFF TRIAC  210 , turning off electrical load  25  and waits for further input. If a speed command was selected in step  240 , the controller  130  advances to step CHANGE TRIAC GATE CONTROL PHASE ANGLE  250 , whereupon step IS STOP COMMAND SELECTED?  260  is executed as noted above.  
         [0069]    It is readily apparent to a person skilled in the art that start and stop and speed control commands may be transmitted to controller  130  by pressing and/or holding air bellows  35  in various sequences, thereby causing air switch  135  to operate in synchronisation and by so doing, transfer user commands.  
         [0070]    Further, a person skilled in the art will be familiar with the execution of controller, sequence steps as described above, including the use of logic decision branches, phase angle control and running loops.  
         [0071]    Numerous modifications, variations and adaptations may be made to the particular embodiments of the invention described above without departing from the scope of the invention, which is defined in the claims. TRIAC GATE CONTROL PHASE ANGLE  250 , whereupon step IS STOP COMMAND SELECTED?  260  is executed as noted above.  
         [0072]    It is readily apparent to a person skilled in the art that start and stop and speed control commands may be transmitted to controller  130  by pressing and/or holding air bellows  35  in various sequences, thereby causing air switch  135  to operate in synchronisation and by so doing, transfer user commands.  
         [0073]    Further, a person skilled in the art will be familiar with the execution of controller, sequence steps as described above, including the use of logic decision branches, phase angle control and running loops.  
         [0074]    Numerous modifications, variations and adaptations may be made to the particular embodiments of the invention described above without departing from the scope of the invention, which is defined in the claims.