Abstract:
A wall structure for a composite tub includes a surface side for facing an interior of the tub, a polyurethane layer backing and attaching to the surface side, plumbing backing the polyurethane layer, and an encapsulation layer encapsulating the plumbing and backing and attaching to the polyurethane layer so that damage to the plumbing is minimized.

Description:
RELATED APPLICATION 
     This application is a United States National Phase of PCT Application No. PCT/US11/50376 filed on Sep. 2, 2011, which claims priority to U.S. Provisional Application No. 61/413,575 filed on Nov. 15, 2010. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to composite bathing vessels. 
     BACKGROUND 
     Bathing vessels may be manufactured from a variety of different materials, such as plastic materials. Plastic bathing vessels, however, must meet certain minimum performance requirements. For instance, the American National Standards Institute (ANSI) sets forth minimum physical requirements and testing methods for plastic bathtub and shower units. A bathing vessel that meets the requirements is approved for use in homes, buildings or other structures as a plumbing fixture. 
     Therapy bathing vessels commonly referred to as air tubs and whirlpools, use piping through with the air and/or water is moved to provide a massaging experience for which they are known. Therapy tubs are typically manufactured using a thermoformed surface layer backed with thermoset polyester that is reinforced with fiber glass. This method of construction has been in practice for many years. The bathing vessel is manufactured and holes are then drilled in locations into the piping for the water to feed the pump and the water and/or air to enter the bath. 
     The water and/or air is moved through external piping that is connected from the pipe or blower to the holes in the bathing vessel. A more recent method utilizes channels that are incorporated into the structure of the bathing vessel and are encapsulated within the polyester reinforcing composite material. 
     SUMMARY 
     According to an embodiment disclosed herein, a wall structure for a composite tub includes a surface side for facing an interior of the tub, a polyurethane layer backing and attaching to the surface side, plumbing backing the polyurethane layer, and an encapsulation layer encapsulating the plumbing and backing and attaching to the polyurethane layer so that that damage to the plumbing is minimized. 
     According to a further embodiment disclosed herein, a wall structure for a composite tub includes a surface side for facing an interior of the tub, a polyurethane layer backing and attaching to the surface side, a cap layer encapsulating the polyurethane layer, and plumbing backing the cap layer such that damage to the plumbing is minimized. 
     These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a therapy tub incorporating an embodiment of the invention. 
         FIG. 2  is a side view of a first embodiment of a construction of a side wall of a tub of  FIG. 1 . 
         FIG. 3  is a side view of a second embodiment of a construction of a side wall of a tub of  FIG. 1 . 
         FIG. 4  is a side view of a third embodiment of a construction of a side wall of the tub of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a tub incorporating several embodiments as mentioned. The tub  10  has a ledge  15 , side walls  20 , a bottom  25 , drain  30 , an overflow  35 , and air or water openings  40  through which air or water is distributed to give a user a therapeutic experience. 
     Referring now to  FIG. 2 , a first embodiment of construction of the side wall  20  is shown. The side wall  20  is constructed of several layers starting with a surface side  45  which forms the interior of the bathing vessel, an initial layer relatively thin layer of polyurethane foam  50 , an air or water jet housing assembly  55  which connects conventionally to the water or air opening  40  shown in  FIG. 1  through opening  57 , a relatively thick (relative to said initial layer  50 ) encapsulation layer  65  of rigid polyurethane foam, and a cap layer  70  of rigid polyurethane foam or an elastomer. 
     The surface side  45  of the tub  10  is a thermoformable plastic such as polymethyl methacrylate (PMMA) that is backed with acrylonitrile butadiene styrene (ABS). The plastic is formed into the shape of a bathing vessel by using standard vacuum forming techniques. The initial rigid polyurethane foam  50  supplied to the back side of the surface side  45  provides structural rigidity and may be closed cell. Standard plumbing is installed in or against the thin layer of rigid polyurethane, which includes the piping  60  and the jet housing assembly  55  among other things such as bushings, fittings, connectors, filters, gaskets, etc. 
     After the plumbing  55 ,  60  is installed, the encapsulation layer of rigid polyurethane foam  65  is supplied to encapsulate the plumping. The final layer  70  of high density polyurethane foam or elastomer is then applied, though it is not always required. 
     Referring now to  FIG. 3 , a second embodiment is described herein. This embodiment has an initial layer surface side  145 , an initial layer of polyurethane foam  150  attached thereto, air piping or a channel  160  is then applied to the back of the polyurethane foam  150 , a hole  163  is drilled to allow communication with the air piping or channel  160 , and the installation is then encapsulated with rigid polyurethane foam  165 . The entire assembly is then capped with a layer  170  of rigid polyurethane foam or an elastomer though it is not always required. In this embodiment, the channel  160  may be pushed into the initial layer of polyurethane foam  150  before the initial layer of polyurethane foam  150  cures. 
     Referring now to  FIG. 4 , another embodiment of the invention is disclosed. The embodiment has surface side  245 , an initial layer of rigid foam  250  attaching to the surface side  245 , a hole  263  for air to enter the bathing vessel from a channel  260  that is made of a layer  265  of rigid polyurethane foam and a cap layer  270  of rigid polyurethane foam or elastomer may be placed over the entire assembly of rigid polyurethane foam  250  though it is not always required. 
     The air piping or channel  260  has three legs. A first leg  275  angles away from the cap layer  270  and a back leg  280  attaches to a second leg  285 , which also attaches to the cap layer and also angles away from the cap layer  270 . The legs  275 ,  280 ,  285  are also made of a rigid polyurethane foam. Because the legs  275 ,  280 ,  285  are made of the same material as the cap layer  270  when constructing the channel  260  or attaching it to the cap layer  270 , a chemical bond is obtained that is both strong and not prone to leak. The channel  260  may then be covered with another layer of elastomeric foam  290 . In this embodiment, the channel  260  may be pushed into the cap layer  270  before the cap layer  270  cures to obtain a chemical bond therebetween. 
     Issues with external piping are related to their exposure during packaging, transportation and installation that may cause them to come loose or otherwise be damaged, resulting in leaks. Heretofore, it has not been feasible to encapsulate plumping piping within the composite structure of the therapy bathing vessel due to the amount of material required and the nature of the application of this material. This disclosure allows for the use of fixed plumbing, to minimize residual water entrapment and encapsulate the plumbing within the composite structure to minimize the risk of damage. 
     Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments. 
     The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.