Abstract:
An air bath has air outlets extending around the side walls of the water basin. Air is delivered to the air outlets through a ring-like air manifold coupled to a blower by conduit. The conduit has a bypass vent that siphons off a portion of the air flow otherwise passing to the air outlets and maintains the blower in communication with ambient air. The air delivery system provides a wider range of bubble densities by allowing the blower to operate at lower speeds without overheating or stalling from back pressure arising from the pressure head of the water in the basin.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to bathtubs in which air is bubbled into the water, and in particular to air delivery systems for such bathtubs. 
     Therapeutic water baths and pools are well-known. Spas or whirlpool tubs are common examples in which water streams from jets through the walls of the basin flow into the water beneath the surface, usually directed at muscle areas of a person&#39;s body, for example shoulders, back and thighs. The force from the jets “massage” the bather directly, as well as agitate the water, to provide therapeutic effects for other parts of the body not directly in the path of the jets. U.S. Pat. No. 6,185,757 discloses one such bath with water jets. 
     Some tubs instead use air streams to agitate the water. U.S. Pat. Nos. 5,898,958 and 6,317,903 each disclose a tub that introduces air into the water from a blower or air pump passed through conduits and a manifold to air jets in the walls of the tub. The air delivery systems in these patents are rather complex and may require a separate conduit for each air jet. 
     Co-pending and co-owned U.S. patent application Ser. No. 10/774,123, filed on Feb. 6, 2004, the disclosure of which is hereby incorporated by reference, discloses an air bath with an improved air distribution system that alleviates dead zones (or non-air infused pockets of water in the tub) to more consistently achieve full body treatment. That system helps overcome a problem of the air jets, particularly those farthest from the blower, becoming blocked by the pressure head of the water in the tub, particularly when the blower speed is decreased. The air jets are arranged in rows that extend essentially around the entire perimeter of the basin. The rows of air jets are spaced apart vertically so that the air jets in each row realize a different pressure head, the vertically higher the air jets, the less the pressure head. Thus, when the water level is high and/or the blower is running at a low speed such that the air jets in the lower rows become effectively blocked, air can still flow through the air jets in the higher row(s), thereby maintaining bubbling around the entire perimeter of the basin. 
     If all the air jets were to become blocked and stay blocked long enough, back pressure could build up sufficient to stall the blower. Heat or current limiting circuitry would have to be provided to shut down the blower motor to keep it from being damaged. A damaged blower motor would render the air system inoperable, and replacement motors are expensive, and typically require a service call from a technician, further adding to the cost. Even if damage to the motor could be avoided, it may still disrupt operation of the bubbling and destroy the air bath. 
     The system described in the aforementioned patent application helps protect the blower to some extent by keeping open an outlet for the air flow from the blower. However, to avoid even the uppermost air jets from becoming blocked, the blower must be selected and operated at sufficiently high speeds to overcome the pressure head. This somewhat limits the ability to provide soft, low density bubbling, without the use of supplemental tanks or accumulators, as described in U.S. Pat. No. 4,907,305. 
     U.S. published application 2003/0233704 discloses a bathtub with an air distribution system that can have a pressure relief valve upstream from the air jets to relieve excess pressure from the blower and prevent it from overheating. Thus, this system requires valving that opens in the event of an excess pressure situation to protect the blower motor. And, since this is merely a protective measure, the system does not provide for more subtle bubbling. 
     Hence, a need exists for bubble tubs improved relative to these deficiencies. 
     SUMMARY OF THE INVENTION 
     The invention provides an improved air delivery system for an air bath and an air bath incorporating the improved air delivery system. With the present invention, an enhanced bathing experience is achieved through a wider range of bubble densities. 
     Specifically, the air delivery system includes a blower generating air flow, a bypass vent in communication with ambient air, and conduit extending between the blower and the air outlets and communicating at least a portion of the air flow to the bypass vent. 
     In preferred forms, the bypass vent is an opening in the conduit between the blower and the air jets, for example at a T-section located in a back flow preventing loop just downstream from the blower. The back flow preventing loop, which extends vertically up to a height at or above a fill height of the basin, and a check valve, such as a spring ball check valve, in line with the conduit prevent water from backing up into the blower. The check valve and bypass vent can be located in any suitable location in line with the air flow upstream from the blower. For example, the bypass valve can be located upstream from the check valve or between the check valve and the air outlets. In any case, both the bypass vent and the check valve are preferably located at or near the back flow preventing loop. 
     The bypass vent preferably stays open to ambient air, and thus no valving is necessary. The flow volume through the opening is selected to ensure that during normal operation a (preferably greater) portion of the blower air flow passes to the air outlets and a (preferably lesser) portion of the air flow passes through the bypass vent. This proportion is affected by the sectional area of the opening relative to that of the conduit. 
     In a preferred case, the sectional area of the opening is less than one half that of the conduit, and more preferably is between 10 and 40 percent of the sectional area of the conduit. The size of the vent opening can thus be selected to create a desired bubbling effect in the basin water. By bypassing more or less air from the air outlets, there is correspondingly more or less bubbling in the basin water in terms of both the quantity and flow rate of the bubbles. 
     The bypass vent also plays a vital role in protecting the blower from overheating, particularly when operating a lower speeds. Since the bypass valve is open to ambient air, if the back pressure from the water head in the basin is too high for positive air flow through the air outlets, all of the air from the blower can be redirected out of the bypass valve. Since the air in this case will be passing through a smaller passage than during normal operation, there will be somewhat more back pressure on the blower, albeit not enough to cause the blower to stall, or otherwise overheat and damage the blower. As mentioned, the problem with the water pressure head blocking flow through the air outlets is most likely to arise at a low flow volume/rate, especially when the water in the basin is high. With the bypass valve, the blower can operate at low speed without stalling or overheating. As mentioned above, this gives the user a wider range of bubbling effects, particularly more subtle, softer feeling bubbles. 
     In addition to protecting the blower, the bypass vent also reduces or prevents chattering of the check valve that can occur in closed systems when the back pressure is about equal to the pressure from the blower. By relieving back pressure, the check valve is quieted. 
     In other preferred forms, a filter, such as one or more mesh screens, can be used to cover the opening and break up the exiting air flow to lessen noise. The filter may diminish flow volume through the bypass vent somewhat, and thus should be considered when sizing the vent opening. An air manifold can be provided to couple the conduit to the air outlets. The air manifold can be one or more channels extending around, and possibly integral with, the side walls of the basin. 
     Moreover, an electronic control and control interface can allow the user to quickly and easily adjust the air to one or more zones (feet, back, shoulders, etc.) by the press of a button. The control can also be used to control the speed of the blower to adjust the air flow rate through the manifold, and thus the density and force of bubbles in the water. 
     Another aspect of the invention is an air bath having an improved air delivery system. The air bath includes the basin having a bottom and side walls and the air delivery system, which includes the blower, a plurality of air outlets extending through the side walls in spaced relation, conduit extending between the blower and the air outlets, and a bypass opening in the conduit in communication with ambient air for maintaining the blower in communication with the ambient air during operation. 
     The above and other advantages of the invention will be apparent from the detailed description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an air bath according to the present invention; 
         FIG. 2  is an enlarged partial perspective view showing components of the air delivery system; 
         FIG. 3  is plan view thereof; 
         FIG. 4  is an enlarged partial sectional view taken along line  4 - 4  of  FIG. 1  showing air outlets in the side walls of the basin; 
         FIG. 5  is a partial sectional view taken along arc  5 - 5  of  FIG. 3  showing a check valve; 
         FIG. 6  is a partial sectional view taken along line  6 - 6  of  FIG. 2  showing a bypass vent; and 
         FIG. 7  illustrates schematically the vented air delivery system providing multiple air treatment zones that can be independently controlled. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1 , an air bath  10  has a basin  12  defining a bottom  14  and contoured upright side walls  16 . The bottom  14  has a drain opening with a drain stop controlled preferably remotely by an actuator having an overflow feature. It should be noted that while shown and described as a bathtub, the air bath  10  could be in other forms, such as a spa or swimming pool. 
     The side walls  16  of the basin  12  are formed with a plurality of openings defining air outlets  22 , preferably in the lower half of the side walls  16 . The air outlets  22  are simple round holes extending though the thickness of the side walls  16 . The air outlets  22  are preferably sized and arranged in a special pattern designed to provide improved air flow for full body air induced hydrotherapy, as disclosed in the co-owned and co-pending U.S. patent application Ser. No. 10/774,123, filed on Feb. 6, 2004. 
     Briefly, the air outlets  22  are arranged in a plurality of lateral (or horizontal) rows, three are shown in  FIGS. 1 and 4 , that essentially ring the entire perimeter of the side walls  16 . If air outlets in lower rows become blocked by water pressure head being greater than the force of air exiting the associated air outlets, air may still flow from air outlets in one or more of the higher rows because of the decreased pressure head. Since the rows essentially ring the basin  12 , full body treatment is achieved and maintained without unintended “dead spots” in the water (where little or no air flow occurs), which is particularly a problem when air flow is decreased for softer bubbling. 
     Preferably, the air outlets  22  are all in communication with an air manifold  24 , which can be a single channel that rings the entire outer side perimeter of the side walls  16 , or which can be a series of discrete channels (as shown in  FIG. 1 ) that are in communication with groups of air outlets corresponding to different treatment zones. In either case, the air manifold  24  can be a separate channel (or channels) mechanically attached and sealed to the basin  12 , or more preferably it can be a unitary part of the cast or molded basin  12 . 
     With reference to  FIGS. 2 ,  3  and  7 , the air bath  10  has an air delivery system for infusing the bath water with air through the air outlets  22 . Air is generated by an air pump or blower  26 . The blower  26  is preferably operable at different speeds, and includes a multiple or variable speed motor  28 . 
     The air flow is routed to the air outlets  22  by air lines or conduit  30  coupling an outlet  32  of the blower  26  to the air manifold  24 . The conduit  30  can be any suitable rigid or flexible plumbing lines, however, preferably PVC tubing with a standard inner diameter is used. As is conventional, various lengths of the PVC tubing is assembled with straight or angled couplers to create the desired routing pathway. 
     As shown in  FIGS. 1 and 7 , the air delivery system includes conduit air lines ( 40 A,  40 B,  40 C and  40 D) for each of the channels ( 24 A,  24 B,  24 C and  24 D) of the air manifold  24 . Air flow through air line  40 A and channel  24 A is controlled by a butterfly valve  42 A. Air flow through both air lines  40 B and  40 C and respective channels  24 B and  24 C is controlled by a single butterfly valve  42 B. Air flow through air line  40 D and channel  24 D is controlled by butterfly valve  42 C. All of the valves are independently controllable by the controller  44  and electronically actuated actuators  46 A- 46 C connected to the controller  44  (which is connected to power supply  47 ). A user control  48  for this system can have a touch pad or other button for the bather to select the zone to supply air to, which signals the controller  44  to open or close one or more of the valves  42 A- 42 C. A full-body selection can also be provided on the user control for simultaneously opening all three valves  42 A- 42 C. 
     As shown in  FIGS. 2 and 3 , the conduit  28  also forms a water back flow preventing loop  50  near the blower  26 , generally in an inverted U-shape, a horizontal leg  52  of which is located at, or above, the maximum fill level of the basin  12 , which generally is at the height of the overflow. Should water back up from the basin into the conduit, the column of water in the downstream vertical leg  54  of the loop  50  should not normally rise high enough to pass through the horizontal leg  52  and down the upstream vertical leg  56  of the loop  50 . 
     In addition, a normally closed, spring-biased ball check valve  60  is disposed in line with the upstream vertical leg  56  to positively close off back flow to the blower  26 , as shown in  FIG. 5 . It should be noted that in this vented system, the check valve  60  is less likely to “chatter”, or oscillated rapidly between seated and unseated positions, which can occur in closed systems when the back pressure is about equal to the pressure from the blower. The check valve  60  here thus operates quietly. 
     Referring to  FIGS. 2 ,  3  and  6 , at the junction between the outlet of the blower  26  and the upstream vertical leg  56  of the loop  50  is a T-shaped coupler  70  with a lower end not coupled to a leg of the loop  50 . This end forms a bypass vent  80 . More specifically, a short section  82  of conduit defining a cylindrical recess  84  at concentric with a small diameter cylindrical opening  86 . A plug  88 , also having a small diameter cylindrical opening  90 , fits (and is secured by adhesive) into the recess  84  of the short section  82  to capture one or more mesh screens  92  therebetween so that they cover the opening  86  and cut down on noise. Instead of screens, foam pieces or other sound deadening materials may be used, as could any other suitable breathable filter elements. 
     The opening  86  (along with opening  90 ) thus forms the bypass vent  80  in that it opens the conduit  30 , and thereby the blower  26 , to ambient air. The bypass vent  80  must create enough back pressure so that under normal operating conditions some, in fact most, of the air flow passes onto the air outlets  22  and into the water, which creates its own back pressure. The primary way of achieving this is by sizing the opening  86  smaller than the inner diameter of the conduit  30  so that only a portion of the air flow from the blower  26  exits through the opening  86  during normal operation. 
     In a preferred case, the sectional area of the opening  86  is less than one half the sectional area of the conduit  30 , and more preferably is between 10 and 40 percent of the sectional area of the conduit  30 . Still more preferably, the opening is circular in cross-section and has a diameter less than 1 inch, for example ⅜ to ½ inch or even smaller. The inner diameter of the conduit  30  is preferably less than 3 inches, for example 1.5 or 2 inches. The air jet openings are preferably less than ¼ inch in diameter. The size of the opening  86  can thus be varied as needed for the flow requirements of a particular application and selected to create a desired bubbling effect in the basin water. By bypassing more or less air from the air outlets, there is correspondingly more or less bubbling in the basin water in terms of both the quantity and flow rate of the bubbles. 
     Should the back pressure from the pressure head of the water be great enough to essentially block all of the air outlets  22 , the air flow in the conduit  30  will build up somewhat until it overcomes the back pressure of the bypass vent  80  and begin flowing through the opening  86  (and opening  90 ). While operating against slightly higher back pressure, the blower  26  can continue to operate without heating excessively or stalling. After the back pressure at the air outlets  22  has diminished sufficiently, the air flow through the conduit will resume its normal routing, with most of the air passing on to and through the air outlets  22 . 
     As shown in  FIG. 7 , the bather can operate the user control  48  mounted on or near the basin  12  to operate a controller  44  to turn on and off the blower  26  as well as to adjust the bubbling effect by changing the motor speed of the blower  26 . As discussed, the bypass vent allows the user to operate the blower at lower speeds for a softer, more subtle bubbling without the associated risk of damaging the blower motor otherwise present in other systems. 
     Finally, to further enhance the bathing experience, the air bath  10  can include a chromatherapy system  100  (including light box  102  and lights  104  mounted to the side walls) to illuminate the bath water various colors. Suitable chromatherapy systems are disclosed in U.S. Pat. Nos. 6,360,380 and 6,752,517, both of which are owned by the assignee of the present invention and incorporated by reference in their entirety as though fully set forth herein. The user control  48  and controller  44  can also be used to operate the chromatherapy system  100 . 
     A preferred embodiment of the invention has been described in detail. However, the invention may be applied in a variety of other embodiments which are within the scope of the invention. Thus, to ascertain the full scope of the invention, the following claims should be referenced. 
     INDUSTRIAL APPLICABILITY 
     The invention provides a vented delivery system for bringing air to air outlets in bathtubs and the like.