Abstract:
A bathing device, such as a bathtub, a tub shower, a shower, a spa and a pool, comprises a substantially iron-free shell and at least one heating pad in direct conductive heat exchange contact with the shell. It also relates to a method for manufacturing a heated bathing device.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1) Field of the Invention  
         [0002]     The present invention relates to bathing devices and, more specifically, to bathing devices having a heated shell and to a method to heat the shell of a bathing device.  
         [0003]     2) Description of the Prior Art  
         [0004]     Soaking in a bathtub filled with warm water produces relaxing effects on the human body. To be pleasant, water is usually above 26° C., which is warmer than ambient air. Thus, the water slowly cools down producing displeasing effects on the bathtub&#39;s user. To warm up the bathtub water, the user usually releases bathtub water to add new water which is warmer than the one released. This process presents several disadvantages. This is not ecologically friendly since drinkable water is wasted. Moreover, it is more expensive to warm water from the waterworks system than water at the ambient temperature. Thus, there is a need to maintain the temperature of the water contained in the bathtub at a constant temperature and have a warm shell in contact with the user&#39;s body for more enjoyable sensation. However, the combination of electricity and water is not usually considered a safe mix.  
         [0005]     U.S. Pat. Nos. 1,389,050, 1,941,832, and 2,301,761 describe bathtubs having a heating system located under the shell in a heating chamber. In these cases, the heating system heats the air located in the chamber and, thus, indirectly the bathtub. This is not an energetically efficient system since an important volume of air needs to be heated to transmit air to the bathtub shell by convection and, then, the heat needs to be transmitted through the bathtub shell by conduction. For an improved heat transfer, these systems require a blower for an increased air circulation. U.S. Pat. No. 3,157,774 describes a bathtub for physiological heat treatment. The bath is a double container having an outside shell and an inside shell. A heat exchange liquid and a heating element are located between the outside and the inside shells to indirectly heat the treatment liquid. As for the above-mentioned patents, this is not an energetically efficient system since the heat transfer occurs through a second liquid that has to be heated. Moreover, the system requires an agitator from an improved heat transfer and it is impossible to enjoy the heat benefit without using the therapeutic system.  
         [0006]     U.S. Pat. No. 1,669,773 describes a bathtub having an electrically heated bottom or heated walls. The object of this invention is to dispose heated coils against the exterior surface of the bathtub shell. However, the surface where the heated coils are disposed must be made of metal to prevent deformation and conduct heat. Similarly, U.S. Pat. No. 3,108,170 describes a heating element directly mounted on the steel core of the bathtub. The heating element comprises a resin coating, such as Teflon™ applied on the outside surface of the bathtub shell, a metallic resistor applied on the resin coating, and a silicon varnish layer covering the metallic resistor. Actual bathtubs do not have a steel core and are usually made of acrylic or fiberglass. It would be difficult, almost impossible, to apply the heating element of U.S. Pat. No. 3,108,170 directly on the surface of a modern bathtub.  
       SUMMARY OF THE INVENTION  
       [0007]     It is an object of the invention to provide a new method and apparatus to maintain warm water inside bathing devices and provide a warm shell. The method is intended to be easily adaptable to usual production lines and safe.  
         [0008]     One aspect of the invention provides a bathing device comprising a substantially iron-free shell; and at least one flexible heating pad in direct conductive heat exchange contact with the shell.  
         [0009]     Another aspect of the invention provides a heating source in combination with a bathing device having a substantially iron-free shell with an outer surface, the heating source being in a fluid gap free contact with the outer surface and being adapted to provide heat thereto by heat conduction.  
         [0010]     A further aspect of the invention provides a method for manufacturing a heated bathing device having a plastic shell the method comprising the steps of adhesively applying at least one flexible heating source in direct contact conductive heat exchange with at least one section of the shell. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:  
         [0012]      FIG. 1 . is a perspective view of a bathtub shell having a heating membrane laminated on its outer surface in accordance with an embodiment of the present invention;  
         [0013]      FIG. 2  is an exploded perspective view of the bathtub shell with the heating membrane of  FIG. 1 ; and  
         [0014]      FIG. 3  is a perspective view, partly sectioned, of a shower having a heating membrane disposed under a flooring surface in accordance with another embodiment of the present invention. 
     
    
       [0015]     It will be noted that throughout the appended drawings, like features are identified by like reference numerals.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]     Referring to  FIG. 1 , there is shown that a bathing device such as a bathtub  10 , either a conventional or an hydromassage bathtub, has a shell  12  adapted to contain a pool of water (not shown). The bathtub shell  12  has an inner face  14 , an outer face  16 , and a surrounding rim  18 . The shell  12  shown on  FIG. 1  has two vertical longitudinal walls  20 , two vertical transversal walls  22 , and a bottom surface  24 . The bathtub shell  12  can be made of any appropriate plastic material (thermoset or thermoplastic type) known by one skilled in the art such as acrylic, acrylic reinforced with fiberglass, fiberglass, gelcoat reinforced with fiberglass, ABS acrylic, ABS reinforced or not with fiberglass, acrylic-ABS co-extrusion sheet molding compound or similar close mold process, any material defined in ANSI Z124 standard series and CSA B45 (Plumbing fixtures), and the like.  
         [0017]     For heating or keeping the pool of water contained in the shell  12  at a predetermined temperature, a heating membrane  30 , or a heating pad or mat, preferably flexible, is mounted to the outer face  16  of the shell  12 . The heat generated by the membrane  30  is transmitted by direct conduction to the shell  12  and then to the pool of water contained therein.  
         [0018]     Referring to  FIG. 1 , it will be seen that the membrane  30  is mounted to both vertical transversal walls  22  and the bottom surface  24  of the shell  12 . However, it is appreciated that the membrane  30  can be mounted on any wall or surface of the shell  12  and that the shell  12  can include more than one membrane  30 . For example, it can be disposed proximate to the armrests, the seats or the backrests. To provide energy to heat the membrane  30  and subsequently the shell  12 , the membrane  30  is operatively connected to a power supply  33  through an electric wire  34 .  
         [0019]     The heating membrane  30  can be operatively connected to an electronic control system  35  or any control device to control the operation of the membrane  30  such as the on/off operation and the heat level provided to the shell  12 . The control system can be operatively connected to a touchpad display (not shown). The touchpad gives the opportunity to the user to start the heating system and select the desired intensity. If several membranes  30  are mounted to the shell  12 , each membrane  30  can preferably be controlled independently.  
         [0020]     The membrane  30  can be mounted to the shell  12  in several ways. For example, an acrylic plastic sheet can be thermoformed into a predetermined shape and then placed on a jig support. Fiberglass is sprayed on the outer surface of the thermoformed part to reinforce the shell  12 . Then one or several membranes  30  are then applied at predetermined locations on the outer surface  16  over the wet fiberglass and an additional layer  32  of fiberglass is sprayed over to firmly maintain the membranes  30  thereon, protect the membrane  30  from outside elements, and prevent access thereto for safety reasons. The membrane  30  is thus encapsulated between two polymeric membranes. A person skilled in the art will appreciate that other materials than fiberglass can be used to reinforce the shell  12  and cover the membrane  30 . The outer layer is however not compulsory.  
         [0021]     The membrane  30  can include a heating layer  37  covered by a conductive material pocket to ground the membrane  30  and provide an increased security for the bather who is resting in the heated bathing device  10 . For example, the membrane  30  can include a 3/1000 inch aluminum foil pocket. Other conductive material pockets such as copper and brass can be used. Moreover, the thickness of the conductive material pocket can vary. The heating layer  37  can be inserted into the conductive material pocket before being applied to the shell  12  or can be mounted between two conductive material sheets while being mounted to the shell  12 .  
         [0022]     For example, referring to  FIG. 2 , it will be seen that a first sheet  36  of conductive material is first mounted to the shell  12 , the heating layer  37  is then adhesively applied to the first sheet  36  of conductive material and is covered by a second sheet  38  of conductive material. The conductive material sheets  36 ,  38  or pocket can be mounted to the shell  12  with fasteners or any other means known to one skilled in the art but are preferably adhesively mounted thereto.  
         [0023]     Self-adhesive conductive material sheets  36 ,  38  and heating layers  37  can be provided to facilitate their adhesion either to the shell  12 , to the conductive material sheet  36 ,  38  or to the heating layer  37 . A pressure-sensitive adhesive, epoxy or cement can also be used to mount the heating layer  37  or the conductive material sheets  36 ,  38  to the shell  12 .  
         [0024]     After the membrane  30  has been mounted to the shell  12 , a second layer, such as a fiberglass layer, can be applied. Additional layers (not shown) can also be provided over the membrane  30  to prevent heat losses in the ambient air and increase the energy efficiency of the heat transfer process.  
         [0025]     The voltage of the membrane  30  can be any value that does not provide any danger for the bather. For example, for Canada and United States, the voltage of the membrane  30  can be 110 and 120 volts. For Europe, the voltage can be 220 and 240 volts. It is also possible to use lower or higher values depending on the user&#39;s needs. Preferably, the membrane  30  has typically a rating of 120 watts or below. The maximum temperature reached by the shell  12  is below 95° C., preferably below 85° C.  
         [0026]     Several types of heating membrane  30  can be used such as wire or foil elements embedded within a pad or mounted to a membrane. For example, it can consist in an etched foil resistive element laminated between layers of flexible material.  
         [0027]     Referring to  FIG. 3 , it will be seen that a membrane  130  developed for floor heating systems can also be used. The heating membrane  130  includes a cable  150  mounted to a mat  152  such as a polymeric mat or a metallic mat, which can be a self-adhesive mat for easily mounting the membrane  130  to the shell  112 . In addition to a heating wire (not shown), the cable  150  can include a ground wire for an increased security and an insulation wire (not shown). The mat  152  is unrolled and applied, preferably adhesively, to the shell  112 . In  FIG. 3 , the membrane  130  is mounted to the bottom surface  124  of a shower  110 .  
         [0028]     One skilled in the art will also appreciate that the membrane  130  can include conductive material sheets  36 ,  38  or be laminated between fiberglass layers.  
         [0029]     Nickel coated carbon fibers laminated in thermoplastic, elastomeric, composite or other sheet films can also be used as membranes  30 ,  130 .  
         [0030]     The membrane  30 ,  130  preferably provides a uniform heat distribution. It is also preferable to mount the membrane  30 ,  130  to the shell  12 ,  112  in a manner such that it is in intimate contact all over the surface beneath, or in fluid gap free contact, as any gaps can block heat transfer. Therefore, membranes  30 ,  130  that are flexible and can fit many sizes and shapes are preferable.  
         [0031]     The heating membrane  30 ,  130  can be applied to other bathing devices than bathtubs and shower floors. For example, it can be applied to any shower wall, pools, shower or bath seats, tub showers, spas, and the like.  
         [0032]     The membranes  30 ,  130  applied on the bathing devices allow to maintain the water at a constant temperature. They also provide a warm shell in contact with the user&#39;s body for more enjoyable sensation. It also provides muscular relaxing effect. The relaxing and enjoyable heat effect can be increased by applying more heat in predetermined areas of the shell.  
         [0033]     The embodiments of the invention described above are intended to be exemplary only. For example, the heating membrane  30 ,  130  can be applied to already existing bathing devices or can be mounted to the bathing device shell by the manufacturer. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.