Abstract:
A manually driven bathtub lift for assisting persons of limited strength or mobility into or out of a typical bathtub without the high costs associated with pneumatic, hydraulic or electric lift devices. A seat is attached to a wheeled trolley arranged for movement up an inclined track mounted on a base frame. A chain is disposed about a drive sprocket and a set of guide pulleys and attached to opposite ends of the trolley. The set of pulleys includes an idler that is biased to retain tension in the chain. The drive sprocket is driven by the rotation of a driver wheel supported on the same shaft as the sprocket. Rotation of the sprocket drives the chain which in turn moves the trolley and attached seat. The driver wheel has handles circumferentially spaced around it and is of large enough size that it can be reached and operated from the seat. The lift is light to allow for easily installation and removal and does not require significant strength to operate.

Description:
[0001]     The present invention relates to a mechanical bathtub lift seat apparatus for assisting persons of limited mobility, such as the elderly or disabled, transfer into or out of a typical bathtub.  
       BACKGROUND  
       [0002]     Persons having permanently limited mobility or strength to due to age or disability may have difficulty performing certain typical daily tasks. Entry to or exit from a bathtub is an example of such a task, as it requires transition between a standing position outside the tub and a seated position upon a very low surface within the tub, including climbing over the side wall.  
         [0003]     As a result, there are a number of existing products aimed at assisting a user enter and exit the tub by easing the aforementioned transition. These products include inflatable chairs positioned within a bathtub for lowering and raising the user to and from the bottom of the tub in a constantly seated position. Other seat assemblies can be positioned within a tub for the same purpose, but are driven by water actuated cylinders or electric motors. Some of these assemblies feature rotating seats so that the user can initially sit with his/her legs outside the tub and then rotate their legs over the tub wall before being lowered, eliminating the step of unassisted entry to the tub altogether. Other devices, typically driven by electric motors, are capable of actually transferring the user from a seated position entirely outside the walls of the tub to a seated position within. One lowering system involves a band spanning from a wall-mounted dispenser on one side of a tub to the wall of the tub opposite the dispenser. An electric motor within the dispenser slowly dispenses more length of the band in order to lower a user seated on the band into the tub. Once bathing is completed, the motor is run in an opposite direction to retract the band into the dispenser, thereby lifting the user back up to the top of the tub.  
         [0004]     The primary problem associated with the existing bathtub lift devices is the high cost involved. The need for components such as air compressors, seals and adaptors for water driven devices, electric motors and control systems, coupled with possible installation costs, keeps many of these products financially out of reach for many of those in need of the assistance that would be provided. Many elderly or disabled persons live on limited income and cannot justify the high cost of the existing bathtub lift systems despite the comfort and safety levels they offer. As a result, there is a need for a bathtub lift apparatus that can be produced and sold at a reasonable cost.  
       SUMMARY  
       [0005]     According to one aspect of the present invention there is provided a bathtub lift apparatus for assisting a person into and out of a bathtub comprising:  
         [0006]     a base frame for being received in the tub, the base frame including a track supported on the frame having a lower end and an upper end;  
         [0007]     a trolley supported for movement along the track;  
         [0008]     a seat for supporting the person thereon, the seat being supported on the trolley device for movement with the trolley between a lower position at the lower end of the track and an upper position at the upper end of the track;  
         [0009]     a rotatable drive member supported for rotation on the frame;  
         [0010]     an elongate driven member engaged about the drive member and connected to the trolley for displacement of said trolley as the drive member is rotated; and  
         [0011]     a driver device for rotating the drive member.  
         [0012]     Preferably the base frame comprises two laterally spaced parallel walls, wherein the drive member and elongate driven member are located between said walls.  
         [0013]     Preferably the track comprises two laterally spaced track members, each having an upper and lower surface defining an elongate channel therebetween for receiving the trolley.  
         [0014]     Each of the upper and lower surfaces of the track members may comprise a rail.  
         [0015]     Alternatively, the upper surface of each track member may comprise a rail while the lower surface of each track member comprises the base frame.  
         [0016]     Preferably there is provided roller members supported on each side of the trolley supported for movement along the track.  
         [0017]     Preferably the roller members are supported in pairs on axles mounted to the trolley.  
         [0018]     Preferably the track is non-linear between the upper and lower ends thereof.  
         [0019]     The seat may be pivotally supported on the trolley for pivotal motion relative thereto.  
         [0020]     In this arrangement, preferably there is provided:  
         [0021]     a pivotal mounting mechanism for pivotally supporting the seat on the trolley for pivotal motion between the lower position where the seat is generally horizontal and the trolley is inclined along the track and a lifting position where the seat and trolley are both inclined along the track and generally parallel to each other; and  
         [0022]     an abutment member mounted on the seat that abuts with the trolley to prevent the seat from pivoting passed the lifting position where the seat and trolley are generally parallel.  
         [0023]     Preferably the elongate driven member is flexible.  
         [0024]     The elongate driven member may be endless.  
         [0025]     Preferably the elongate driven member is guided by idler members supported on the base frame.  
         [0026]     Preferably one of the idler members is floatingly supported on the base frame and biased in order to maintain tension in the elongate driven member.  
         [0027]     Preferably the idler members comprise pulleys.  
         [0028]     Preferably the elongate driven member comprises a chain and the driver member comprises a sprocket for engaging the chain.  
         [0029]     Preferably the driver device comprises a rotational member having a series of handles circumferentially spaced therearound.  
         [0030]     In this arrangement, preferably the handles comprise openings in the rotational member.  
         [0031]     Alternatively, the driver device may comprise a hand crank mechanism for rotating the drive member.  
         [0032]     Preferably the driver device is accessible by the person supported in the seat.  
         [0033]     Preferably there is provided a locking mechanism for selectively preventing motion of the seat relative to the base frame.  
         [0034]     Preferably the locking mechanism is coupled between the driver device and the base frame.  
         [0035]     Preferably the locking mechanism comprises:  
         [0036]     an opening in the driver device;  
         [0037]     a corresponding opening in the base frame;  
         [0038]     a pin for passing through the opening in the driver device into the opening in the frame, thereby blocking motion of said driver device, and hence the driver member, elongate driven member, trolley and seat, relative to said frame.  
         [0039]     Preferably the base frame and the driver device comprise aluminum.  
         [0040]     The present invention can be made and sold at substantially lower costs than existing bathtub lifts as a result of its simple mechanical structure. Assembly is simple and affordable, as the drive system not require any complex, costly or custom components and the base frame is easy to fabricate. The apparatus is hand driven and therefore does not require the use of an external power source, such as an electric motor or air compressor and corresponding control mechanism. Furthermore, the simplicity of the apparatus ensures that any maintenance will be minimal and affordable.  
         [0041]     The driver device is reachable from the seat of the lift and therefore may be used by a bather without outside assistance. The driver device is of substantial size such that the amount of torque needed to lift the bather supported on the seat can be achieved with relatively little force. As a result, the bather does not require a lot of strength to use the apparatus and is therefore less likely to require assistance. Using a material of relatively high strength to weight ratio such as aluminum to construct the frame and driver device, the weight of the apparatus is kept to a minimum so that the lift can be easily lowered into and lifted out of a typical bathtub. This is ideal for the cases where more than one person uses the tub on a regular basis and the lift is not always needed. There is no need for professional installation, which helps keep down the overall cost of the lift apparatus. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0042]     In the accompanying drawings, which illustrate an exemplary embodiment of the present invention:  
         [0043]      FIG. 1  is a side elevational view of the bathtub lift with the seat in the lowered position.  
         [0044]      FIG. 2  is a side elevational view of the bathtub lift with the seat in the raised position.  
         [0045]      FIG. 3  is a rear elevational view of the bathtub lift with the seat in the lowered position.  
         [0046]      FIG. 4  is a rear elevational view of the bathtub lift with the seat in the raised position.  
         [0047]      FIG. 5  is a top plan view of the bathtub lift with the seat in the lowered position.  
         [0048]      FIG. 6  is a top plan view of the bathtub lift with the seat in the raised position.  
         [0049]      FIG. 7  is a cross sectional view of the bathtub lift with the seat in the raised position as taken across line VII-VII of  FIG. 6 . 
     
    
     DETAILED DESCRIPTION  
       [0050]     The following description outlines the details of a bathtub lift for assisting persons of limited mobility, such as the elderly or disabled, transfer into or out of a typical bathtub. One embodiment of the present invention is shown from the side in  FIGS. 1 and 2 . The bathtub lift apparatus  1  features a base frame  10  for supporting the apparatus within the bathtub (not shown), a seat  20  for supporting the bather and a driver device  40  for controlling motion of the seat  20 . The lift functions in such a manner as to move the seat  20  between a lower position as seen in  FIG. 1  and a raised or upper position as seen in  FIG. 2 . The seat  20  has a backrest portion  21  and a bottom portion  22  connected by an angled portion  23 . The user can sit upon the bottom portion  22  in the raised position from outside the tub, rotate his or her body in order to dispose each leg on an opposite side of the apparatus and then descend gradually to the lowered position within the tub. Once finished bathing, the user can then use the control device  40  to ascend back to the raised position and then rotate his or her legs over the tub wall in order to exit the bathtub.  
         [0051]     The movement of the seat is achieved through rolling motion of a trolley  30  attached to the seat  20 . The base frame  10  includes a pair of spaced apart parallel vertical walls  11  each having an upper edge  12  defining generally horizontal lower  17  and upper  18  portions and an inclined portion  16 . The walls  11  are connected and spaced apart at the end of the upper portion  16  by a horizontal base member  13  at the bottom of the frame  10  and vertical end wall  15  disposed above the base member as shown in  FIGS. 3 and 4 . A track assembly  50  is supported on each wall  11 . The track includes a rail  51  which is held above the base frame  10  by rail supports  52  that extend generally perpendicular to the upper edge  12  of the walls  11 . The rail  51  and supports  52  are connected by bolts  53  in order to form a channel  54  defined by a space between the rail  51  and the upper edge  12  of the wall  11 . This channel  54  defines the path along which the trolley  30  can move. The trolley includes wheels  32  disposed on each side of the trolley body  31  for rolling motion within the channel  54 . The track extends along the inclined  16  and upper  18  portions of the upper edge  12  so that the seat  12  attached to the rear end of the trolley  30  can move between the lower position above lower portion  17  to the raised position above the inclined portion  16 . The inclined portion  16  is curved in order to provide a smooth transition of the trolley  30  to and from the upper  18  and lower  17  portions.  
         [0052]     Components of the drive system for the trolley are disposed between the walls  11  of the base frame  10  and are illustrated in  FIG. 7 . A chain  82  is positioned around a drive sprocket  45  and guide pulleys  91 ,  94  and  96  and attached to the trolley  30  at opposite ends. A first end of the chain  82  is attaches to the trolley  31  by means of attachment member  34  bolted to the chain  82  and the trolley body  30  at an end opposite the seat  20 . From this first end, the chain extends around the sprocket  45  down to a floating idler pulley  91  which is mounted on a lever  92  for pivotal movement about an axis defined by a shaft  93  supported at each end by a wall  11  of the base frame  10 . This arrangement allows movement of the idler pulley  91  in order to retain tension in the chain  82  as the trolley  30  moves along the track  50 . The chain extends from the idler  91  over a guide pulley  94  supported between the walls  11  by a shaft  95 . The chain further extends from the guide pulley  94  around a third pulley  96  supported on a shaft  97  near the end of the lower portion  17  opposite the inclined portion  16 . This pulley  96  reverses the chain direction back toward the drive sprocket  45  for connection to a second trolley attachment member  33  at an end of the trolley  30  nearest the seat  20 . Similar to the first attachment member, the second attachment member  33  is bolted to the chain  82  and the trolley body  31 . With the seat  20  in the lowered position as shown in  FIG. 1 , rotation of the sprocket  45  in a clockwise direction drives the chain  82  in a manner that pulls the trolley  30  along the track  50  up the inclined portion  16  to the upper portion  18 , moving the seat  20  toward the upper position shown in  FIG. 2 . The shafts  95  and  97  that support the pulleys  94  and  96  at the lower portion  17  further are connected to a wall  11  of the base frame  10  at either so that they not only support the pulleys, but also keep the walls spaced apart at that end of the apparatus.  
         [0053]     The rotation of the drive sprocket  45  is achieved by means of the control device  40 . The control device  40  includes a drive wheel  49  having a series of handles  41  formed by holes circumferentially spaced around the wheel. As seen in  FIGS. 3 and 4 , the drive wheel is attached to a rotatable member  46  by means of bolts  43 . The rotatable member is fixed on the same shaft  45  as the drive sprocket  81 . The shaft  45  extends transversely through aligned holes in the vertical walls  11  of the base frame  10  near their upper edges  12  at the upper portion  18 . The shaft is free to rotate with respect to the frame  10 , but lateral movement along its axis is prevented by the combination of a pin  48  and blocking plate  47  as shown in  FIGS. 3-6 . The blocking plates  47  are supported on the shaft  45  just outside each vertical wall  11  and the pins  48  pass through openings in the shaft just outside the plates. Lateral movement of the shaft  45  with respect to the frame  10  is prevented by the abutment of either pin  48  with the respective blocking plate  47 . Rotation of the drive wheel  40  and attached rotatable member  46  causes the sprocket  81  to turn and drive the chain  82 , resulting in motion of the trolley  30  and attached seat  20 . The wheel  40  is of sufficient size that the handles  41  are within reaching distance of the user when supported on the seat  20  regardless of the position of the trolley  30  along the track  50 . The amount force needed to pull the seated user up the inclined portion  16  is kept reasonably small as the relatively large radius of the driver wheel  49  ensures a proportionally large resultant torque about the axis of the shaft  45 .  
         [0054]     The force of gravity on the user when seated in the raised position tends to cause the trolley  30  and attached seat  20  to descend down the inclined portion  16  to the lowered position. As a result, a locking mechanism is provided for selectively securing the trolley  30  in the track  50  at the upper portion  18  of the walls  11  of the base frame  10 , thus locking the seat  20  in the raised position above the inclined portion  16 . A hole  42  in the driver wheel  49  is positioned in order to align with a corresponding hole  14  in the wall  11  of the base frame  10  on the same side of the lift apparatus  1  as the wheel  49  when the seat  20  is in the raised position. A pin  70  is passed through the aligned holes  42  and  14  in order to prevent motion of the wheel  49  with respect to the base frame  10 . Since the wheel  49  is attached to the rotatable member  46  which is mounted on the same shaft  45  as the drive sprocket, rotation of any of these components is prevented by the pin  70 . The trolley  30  and seat  20  cannot move with the pin  70  in place as the cogs of the stationary sprocket  81  prevent motion of the chain  82 .  
         [0055]     A pivoting mechanism  60  is provided between the trolley  30  and the seat  20  to allow pivotal motion of the seat with respect to the trolley as they move along the track  50 . A pair of hinges  63  provides the pivoting action between the seat  20  and trolley  30 . Each hinge has flaps  61  and  62  attached to the trolley body  31  and the seat  20  respectively. As shown in  FIG. 1 , the hinge  63  allows the bottom portion  22  of the seat  20  to take on a nearly horizontal orientation in the lowered position at the lower portion  17  of the wall  11  even though the trolley  30  is at an angled orientation along the inclined portion  16 . As the trolley  30  is pulled upward along the inclined portion  16  by the chain  82  the hinge will open further such that the bottom portion  22  of the seat  20  will take on an the same orientation as the trolley  30 , in other words parallel to the inclined portion  16 . An abutment member  64  is attached to the underside of the bottom portion  22  of the seat  20  in order to prevent the hinge  63  from opening more than 180 degrees. In the raised position shown in  FIGS. 2 and 7 , the hinge  63  opens under the weight of the seat  20  (and user, if seated thereupon) and moves the abutment member  64  into contact with the trolley body  31 . This keeps the bottom portion  22  of the seat in a generally horizontal orientation in which the user can easily get on or off the seat  20  for entering or exiting the tub respectively.  
         [0056]     Due to the handles  41  circumferentially disposed about the drive wheel  49  the lift is operable by either the bather or an assistant. The bather is lowered into the tub from the raised position shown in  FIG. 2  by removing the locking pin  70  from the aligned holes  42  and  14  in the drive wheel  49  and wall  11  respectively. The weight of the bather on the seat will tend to move the seat  20  and attached trolley  30  down the inclined portion  16 , pulling on the chain  82  and causing counter clockwise rotation of the sprocket  81  and the attached shaft  45 . Since the driver wheel  49  is mounted on the same shaft  45  by means of the rotational member  46 , the counter clockwise rotation can be resisted by means of the handles  41 , thereby controlling the speed of descent of the bather towards the lowered position shown in  FIG. 1 . In order to exit the tub, the seat  20  is moved upward along the inclined portion  16  from the lowered position by rotating the driver wheel  49  clockwise by means of the handles  41 . Once the seat  20  has reached the raised position, the holes  41  and  14  of the locking mechanism will be realigned so that the locking pin  70  can be inserted to lock the seat in the raised position while the bather dismounts the lift apparatus.  
         [0057]     The above description outlines a single embodiment of the present invention from which a number of alternate embodiments can be derived by those who are skilled in the art. Alternate styles of frames, seats, trolleys, tracks, drive members, driven members and guide members can be assembled to achieve similar results. One alternate embodiment may employ a rope and winch for lifting and lowering the seat, in which case the rope would only have to extend between the winch and the end of the trolley nearest the upper portion eliminating the need for the guide and tension pulleys. Another alternate embodiment could use a notched belt and pulley combination instead of the chain and sprocket. Other embodiments could feature a trolley arranged to move along a single track member or elongate handles extending outward from the drive wheel transverse to the apparatus. The trolley and seat could also be combined into a single rigid component, eliminating the need for the pivoting mechanism. In this arrangement, the track would not extend to a horizontal upper portion of the frame. The trolley would only move along an inclined section of track and therefore would always be oriented at the same angle with respect to the frame. Without the pivot mechanism, the seat would not move relative to the trolley but would remain fixed at an orientation similar to that of the lowered position of the seat in the preferred embodiment, as shown in  FIG. 1 . As a result, the bottom portion of the seat would remain in a generally horizontal orientation when moving between the lowered and raised positions.  
         [0058]     Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.