Abstract:
An elevating bath lift seat for assisting elderly and disabled persons to safely get down into, and back out of a bathtub. it comprises a vertically moving seat surface supported by frame structure designed to be situated within most residential bathtubs. It uses household water pressure to elevate and lower the user. Lifting force is provided by a novel lifting bladder arrangement which is totally sealed without the use of sliding type seals. An integral part of the design is a novel frame structure that also serves as a linear guide system for up and down travel of the seat frame, while also providing full water immersion lubrication for linear guide bushings.

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention relates to relates to a bath lift seat arrangement to assist elderly and disabled persons while transferring into or out of a bathtub, and specifically, to help lower a person down into a bathtub for a full immersion bath, and then following the bath to lift the person up to a height higher than the edge of the bathtub. 
     2. Description of Prior Art 
     Entering and exiting from a typical bathtub may be a difficult process for some elderly or disabled persons. Particularly, rising up from a seated position down within a bathtub requires considerable strength, balance and range of motion which may be limited in some by a disability or effects of aging. 
     However, one solution is to provide a seating surface onto which the bather may sit, whereby the seating surface may be lowered and elevated by powered means, leaving the user with the lesser tasks of managing to transfer on to and off of the seating surface to take a full immersion bath. This function has been presented in prior art devices which are popularly referred to as bath lifts. 
     While various bath lift devices have been available in the prior art, these bath lifts suffer from several shortcomings relating to performance, weight and cost. Most of the prior art devices are cumbersome and heavy to lift due to large frame structures making it difficult for other bathtub users to remove the device from the bathtub when not needed. Some prior art devices have water powered type linear actuators employing rubber type sliding seals that tend to wear out, leak, or stick when allowed to run dry for a period of time. Further, many existing art bath lift seats give the user an unstable feeling in the elevated seat position due to design limitations which permit considerable rocking motions of the seat. Additionally, the complex nature of many of the existing bath lifts result in a prohibitively high cost for many individuals who could otherwise benefit from a bath lift device. 
     A major complaint of existing art bath lift seats is that the horizontal portion of the seat surface is only able to lower to within three to four inches of the bath tub floor surface due to the lifting mechanisms, seat guides, and frame structure being located below the seat surface. This results in an incomplete immersion bathing experience for those persons who could most benefit from complete submersion bathing, and also results in a considerable amount of water wastage during the life of the bath lift device. 
     The present bath lift device is unique in that it addresses the well known shortcomings of the current bath lifts. The present bath lift features a simple design minimizing structure for light weight, and hence ease of lifting and moving. It is also extremely stable in its raised position due to the secure linear seat guidance system. Further, the design allows for an extremely low seat bottom height to allow the bather to sit within under one inch of the floor of the bathtub. The unique lifting bladders offer smooth lifting without the use of sliding type seals which are prone to leakage. 
     SUMMARY OF THE INVENTION 
     According to the present invention, the elevating bath lift seat comprises the following major assemblies: the base frame assembly, the seat frame assembly, the lift bladders, the control pendant, and the manifold assembly. 
     In operation, the seat frame assembly is supported by the base frame and is moved upward and downward guided by the mast tubes of the base frame powered by a pressurized fluid such as domestic water pressure applied to the lift bladders. The lift bladders extend and retract to move the seat surface upward and downward. The flow of water to the bladders is guided by the control pendant and distributed through the manifold assembly. 
     Other objects, features and versions of the present invention will become apparent from the following detailed description, which, when interpreted with the listed drawings, together disclose a preferred embodiment of the invention. It is to be understood that the drawings are intended for the purpose of illustration only, and are not intended as a definition of the limits of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of one embodiment of the present invention with the seat surface in the elevated position. 
     FIG. 2 is a perspective view of one embodiment of the present invention. with the seat surface in the lowest position. 
     FIG. 3 is a perspective view of one embodiment of the present invention as placed in a typical bathtub with user transfer plate. 
     FIG. 4 is a rear perspective view of one embodiment of the present invention. 
     FIG. 5 is a section view I—I of one of the lift bladders as detailed in FIG.  4 . of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the figures, FIG. 1 illustrates one embodiment of the present invention showing the seat surface  1  in the uppermost position. FIG. 2 shows the bath lift seat  2  with the seat surface  1  in the lowermost position. 
     FIG. 3 shows the bath lift seat  2  as typically placed within a typical bathtub with the seat surface  1  in an elevated position. FIG. 3 also shows an optional planar member  10  used to span across from the seat surface  1  to the edge of the bathtub  11  to provide a surface for users to slide thereon to safely transfer to and from the seat surface  1 . 
     FIG. 4 shows a rear view of one embodiment with a top decorative cover removed for clarity. 
     Referring to FIG. 4, the bath lift seat comprises the following major assemblies: the base frame assembly  3 , the seat frame assembly  4 , the lift bladders  5 , the control pendant  6 , and manifold assembly  7 . 
     Referring to FIG. 4, the seat frame assembly  4 , is supported by the base frame  3 , and is moved upward and downward guided by the mast tubes  8 , of the base frame  3 , using a pressurized fluid such as domestic water pressure applied to the lift bladders  5 . The lift bladders  5  extend as will be described herein, and move seat surface  1  upward. The flow of water. to the bladders  5 , is guided by the position of the rocker  9  of the control pendant  6 , and distributed through the manifold assembly  7 . Pressurized water is supplied via the supply hose  93  (shown shortened for clarity), and water is exhausted via drain hose  94 . 
     Turning now to better describe major subassemblies, the base frame assembly  3  shown in FIG. 4, is most preferably fabricated from tubular elements which are lightweight, strong, and resistant to corrosion such as aluminum, or stainless steel in the case of metal tubes, or appropriate plastics known to those skilled in the art. The base frame assembly  3  comprises specifically a pair of tubular side legs  12 , situated parallel or slightly angled to each other, oriented substantially parallel to the bathtub floor, and joined by the cross beam  13 , a tubular element welded between the side legs  12 , onto which is welded the two mast tubes  8 , which are hollow tubes situated parallel to each other, and on a slight backward angle as shown. 
     When fully assembled, both ends of the side legs  12  are covered with end caps  15  which are made from a resilient and flexible material such as rubber and may be fabricated with or without a suction cup feature integrated into the bottom edge of the end caps  15  (not shown). Furthermore, the side legs  12  of the base frame assembly  4  are additionally sealed against water entry while in service by the insertion of plastic end plugs (not shown) inserted within the bore of each end of the side legs  12 . In service, the end caps  15  are intended to be located over user installed friction pads (not shown) installed on the floor surface of the bathtub to prevent motion of the bath lift  2  within the bathtub while in use. 
     Referring to FIG. 4 the seat frame assembly  4 , comprises the seat frame member  16 , preferably fabricated from a formed single piece of lightweight tube such as aluminum, with a horizontal frame member  17 , joined. thereon, spanning across the top ends of the seat frame member  16 . 
     Referring to FIG. 4, also fixed onto the seat frame member  16  are roller support brackets  18 , which hold the roller  19  which is fabricated from a lightweight material such as plastic and has a profile to match and roll on the front cylindrical surface of the mast tubes  8 . The roller  19 , has a centrally located cylindrical hole to receive roller shaft  20  which is fabricated from a corrosion resistant metal, such as stainless steel, and held in place with means known to those skilled in the art such as a circle clip or press fit end cap to prevent side ward motion of the roller shaft  20  while in use. 
     Furthermore, a curved rod member  21 , such as a wireform, covered with a sleeve of a low friction material, is secured with ends pivotally mounted on roller shaft  20 , and located such that the curved member is situated around the opposite side of the mast  8  relative to the roller  19 .to prevent the seat frame assembly  4 , and roller  19 , from pulling away from the mast tube  8  should a lateral or forward force be exerted on the seat frame assembly  4 . 
     Referring to FIG. 4, a seat surface  1 , is secured to the seat frame member  16 , using formed clamps  22 , which wrap around the seat frame member  16  and are held to the underside of the seat surface  1 , with an appropriate adhesive known to those skilled in the art. Seat surface is fabricated from a lightweight corrosion resistant material such as plastic and is formed with a profile to best interface with the body of an average user, advantageously whereby the horizontal portion of the seat is formed with a profile to situate the user closer to the floor of the bathtub when the seat frame assembly  4 , is at its lowest position. 
     Referring to FIG.  4  and FIG. 5, the lift bladders  5  are effectively linear actuators which extend under the application of fluid pressure, and shorten when the fluid contained within is able to exhaust to atmosphere as directed by control pendant  6  and user. 
     FIG. 5 shows a partial section view I—I of one of the mast tubes  8  with lift bladders  5  mounted coaxially thereon. Mounted within each of the mast tubes  8 , are guide bushings  14 , made of a low surface friction material compatible with water immersion and considerable lateral force. Guide bushings  14 , are interference press fit into their corresponding locations within the mast tube  8 , and further held in place with an adhesive. The bore of the guide bushing  14  has a number of narrow longitudinal slots with the intent to reduce weight, cost, permit better water flow along the length of the mast, and permit shrinkage of the outside diameter of the guide bushing  14  when inserted inside the bore of mast  8 . 
     The lift bladders  5 , comprise the following major items: Clamp cap  24  serves as the top end and seal of the lift bladder  5 . Clamp sleeve  25  serves as the bottom end seal of the lift bladder  5 , while also sealing onto the top end of the mast tubes  8 . Telescopic tube  26  is fixed within clamp cap  24 , and is set slidably within guide bushing  14  of mast tube  8 . 
     More specifically, the clamp cap  24 , is functionally the top of the lift bladder and is constructed from a lightweight corrosion resistant material such as a plastic. Referring to FIG. 5, it comprises a bore  27 , to receive the top end of the telescopic tube  26 , with horizontally oriented threaded hole  28  to allow installation of set screw  29 . In addition it has a sealing groove  30 , in which is located an elastomeric band  31  which stores tension from the cylindrical hose clamp  32  to better seal the relatively thin lift bladder material  23 . The clamp cap  24  also has a inlet aperture  33  which allows fluid in to the lift bladders  5  via a 90 degree bend down into bore  27 . The top of the clamp cap  24  has means to allow fastening to the horizontal seat frame member  17  such as a threaded hole  36  for a threaded fastener. The bladder material  23  is a resilient, reinforced membrane such as an elastomeric coated fabric formed into a cylindrical shaped tube with two open ends. The bladder material  23  is able to withstand fluid such as water under pressure without leakage, and flexible enough to repeatedly roll inward moving telescopically within itself during extension and retraction of the lift bladders  5 . 
     The clamp sleeve  25  is fabricated from a lightweight corrosion resistant material such as plastic and comprises a sealing groove  38  to act as a seat for the elastomeric band  39  as well as a groove  40  in which is located o-ring  41  which is intended in operation to seal against the top end of mast tube  8  to prevent leakage of water out of the pressurized environment inside the lift bladder. The clamp sleeve  25  is secured to the top end of mast tube  8  by set screw  42 , held within a threaded hole  43  and engages into dimple  44  in mast tube  8 . 
     The bladder material  23  is clamped at its bottom end using a hose clamp  37  acting on the clamp sleeve  25 . The clamp sleeve has a smaller outer diameter compared to that of the clamp cap  24 . Therefore, the bladder material  23  may have a larger diameter than that of the clamp sleeve  25 . and will need pleated folds at the location of the clamp sleeve  25  in a manner to make a proper seal. To better seal the area of the pleated folds, the inside surface of the bladder material  23 , and outside surface of the clamp sleeve  25 , are covered with an appropriate adhesive sealant known to those skilled in the art to provide a leak tight seal at the area of the pleated folds and hose clamps  37 . 
     Telescopic tube  26 , is a tubular element made from a lightweight and strong material such as aluminum. In the case of aluminum, the surface must be treated to improve its wear resistance and corrosion resistance. Referring to FIG. 5, at the top end of the telescopic tube  26 , is a shallow dimple  45 , allowing the seating of a set screw  29 , to secure the telescopic tube  26  within the bore  27  of the clamp cap  24 . Aperture  98  permits air trapped in the top of the bladder to flow into the inside of telescopic tube  26  to drain out through inlet aperture  33  in the case of water used as the pressurized fluid. 
     The lift bladders  5  comprise bladder material  23 , which is substantially cylindrical in shape and sealed at both ends, whereby the sealing means of the lower end is smaller in diameter than the inside diameter of the bladder material  23 . This configuration permits the bladder material  23  to travel downward over the lower sealing means as shown in FIG. 5 which permits motion of the clamp cap  24  relative to mast  8  employing a totally sealed fluid vessel, without the detrimental use of sliding type rubber seals as used with piston and cylinder bore type linear actuators. 
     Therefore, to shorten the lift bladder  5 , the control pendant  6  is activated to allow the fluid to flow out of the lift bladder  5 . As a result, the clamp cap  24  and telescopic tube  26  moves downward whereby the telescopic tube  26  is confined to move downward axially within the guide bushing  14  within the mast  8 . As the clamp cap  24  travels downward, the bottom leading edge  95  of the bladder material  23  is forced to coaxially roll inward towards the surface of the mast tube  8 , such that it will ultimately cause what was the outward facing surface  96  of the bladder material  23 , to be facing inward against the outer surface of the mast tube  8  as the clamp cap  24  continues to travel downward. 
     Also referring to FIG. 5, to extend the lift bladder  5 , upon application of fluid pressure, the clamp cap  24  is forced to move upward, and bladder material  23  is pulled away from the mast tube  8 , such the bladder material at the position Indicated by point  97  would coaxially fold outward to the position indicated by point  95 . 
     Telescopic tube  26 , is a tubular element made from a lightweight and strong material such as aluminum. In the case of aluminum, the surface must be treated to improve its wear resistance and corrosion resistance. Referring to FIG. 5, at the top end of the telescopic tube  26 , is a shallow dimple  45 , allowing the seating of a set screw  29 , to secure the telescopic tube  26  within the bore  27  of the clamp cap  24 . Aperture  98  permits air trapped in the top of the bladder to flow into the inside of telescopic tube  26  to drain out through inlet aperture  33  in the case of water used as the pressurized fluid. 
     The lift bladders  5  comprise bladder material  23 , which is substantially cylindrical in shape and sealed at both ends, whereby the sealing means of the lower end is smaller in diameter than the Inside diameter of the bladder material  23 . This configuration permits the bladder material  23  to travel downward over the lower sealing means as shown in FIG. 5 which permits motion of the clamp cap  24  relative to mast  8  employing a totally sealed fluid vessel, without the detrimental use of sliding type rubber seals as used with piston and cylinder bore type linear actuators. 
     Therefore, to shorten the lift bladder  5 , the control pendant  6  is activated to allow the fluid to flow out of the lift bladder  5 . As a result, the clamp cap  24  and telescopic tube  26  moves downward whereby the telescopic tube  26  is confined to move downward axially within the guide bushing  14  within the mast  8 . As the clamp cap  24  travels downward, the bottom leading edge  95  of the bladder material  23  is forced to coaxially roll inward towards the surface of the mast tube  8 , such that it will ultimately cause what was the outward facing surface  96  of the bladder material  23 , to be facing inward against the outer surface of the mast tube  8  as the clamp cap  24  continues to travel downward. 
     Also referring to FIG. 5, to extend the lift bladder  5 , upon application of fluid pressure, the clamp cap  24  is forced to move upward, and bladder material  23  is pulled away from the mast tube  8 , such the bladder material at the position indicated by point  97  would coaxially fold outward to the position indicated by point  95 . 
     Referring to FIG. 4, the manifold assembly  7 , comprises manifold block  46 , and Various hoses secured thereto. Manifold block  46 , is fabricated from a lightweight and corrosion resistant material such as plastic. 
     The control pendant  6  is fabricated from a lightweight corrosion resistant material such as a plastic. It comprises a pendant body  57  and rocker  9  and a plurality of valve assemblies contained within of a type known to those skilled in the art. The control pendant is connected to a manifold block  46  by three hoses contained within flexible sleeve  56 . In operation, the control pendant  6  acts as a two way, three position, spring return to center valve system to control flow of water in and out of the lift bladders. 
     For control of the fluid flow to and from the bladders  5 , the rocker  9  has three positions; in center (non-actuated) position, the control pendant  6  permits no flow to or from the bladders  5 . When the rear rocker surface is pressed downward, the control pendant  6  permits flow to bladders  5  from pressure source thereby elevating the seat surface  1 . When the front rocker surface is pressed, flow is permitted from lift bladders to drain thereby lowering the seat surface. 
     Although the invention has been described relating to a preferred embodiment, it should be understood that various modifications, additions, and alterations may be made to the invention by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.