Abstract:
Wheelchair designs and enhancements are provided for use with conventional wheelchair design. The designs and enhancements include bariatric extension panels and security features making it suitable for use in high security areas such as prisons and psychiatric wards.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application claims the benefit of provisional patent Application No. 61/682,888 filed 2012 Aug. 14 by the present inventor. 
    
    
     BACKGROUND 
     Prior Art 
     The following is a tabulation of some prior art that presently appears relevant: 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 U.S. Patents 
                   
               
             
          
           
               
                 Pat. No. 
                 Issue Date 
                 Patentee 
               
               
                   
               
               
                 4,770,432 
                 September 1988 
                 Wagner 
               
               
                 4,917,395 
                 September 1990 
                 Graebe 
               
               
                 5,028,065 
                 Jul. 2, 1991 
                 Danecker 
               
               
                 7,182,356 
                 Sep. 6, 2002 
                 Haase 
               
               
                   
               
             
          
         
       
     
     Background 
     The present disclosure relates generally to wheelchair designs and more particularly to wheelchair designs and related enhancements that include one or more of the following advantageous structural and/or functional features: tamper resistant security features and extension parts to accommodate bariatric users. This wheelchair is used in prisons and psychiatric wards where security is essential. 
     Prisons are dangerous places. Security and the need to reduce potential violence are tantamount. Some residents of a psychiatric ward, a prison or a correctional institution need to use a wheelchair. Traditional wheelchairs create many problems relating to safety for guards and inmates alike. Traditional manual wheelchairs are hazardous in these institutions because they can be made into weapons and users can also carry contraband within them. 
     The same issues apply to psychiatric wards where the users may harm themselves as well as other inhabitants or caregivers. 
     Standard wheelchair construction comprises a welded tubular metal frame having seat and back elements of flexible material or fabric spanning the space between either side of the frame. Such construction is inherently unstable and dangerous in a prison environment. 
     Tubular parts can be disassembled, cut and made into shooting weapons. Notes or drugs can be hidden in any tubular part. 
     Metal parts can be sharpened and used for stabbing or spear like weapons. The fabric seat contains a strip of metal on each side. This metal allows the fabric to be bolted to the frame. Prisoners remove this metal strip. They sharpen this metal to produce a stabbing weapon and hide it. The bolts holding the fabric wear through the fabric in about one week. At this point the guards are able to detect the damage but many times are unable to find the hidden weapon. 
     Removable parts such as footrests are used as a battering weapon. This is a weapon of choice when there is a riot or fight. A footrest used in this fashion can even cause death. 
     Cavities are used to smuggle contraband such as drugs, cell phones, communication notes, or weapons. 
     Therefore care is to be taken to ensure that a wheelchair cannot be disassembled and its parts used to make weapons. Furthermore all material components and all connections of a wheelchair needs to be sufficiently strong to resist being broken and used as a weapon. Prisoners can use a heated wire to cut through thin plastics with low melting points and plastic foam. Prisoners also create a cutting tool with salt coated dental floss. This makeshift tool is able to cut through soft and thin plastic material. 
     Finally bariatric chairs for heavier and larger users have even more metal parts than traditional chairs. There are currently many more bariatric users in these institutions than in previous years and the numbers continue to grow larger. There is a need for a secure bariatric wheelchair. 
     Several security wheelchairs have been proposed. However the security issues were addressing the problem encountered at airports and other venues requiring transport through an x-ray machine rather than the problems encountered in prisons. 
     U.S. Pat. No. 4,770,432 to Wagner discloses a foldable wheelchair constructed of panels of skinned polymeric foam which are secured together by piano type hinges. These hinges require continued maintenance and can easily be disassembled in a prison environment. The polymeric foam can be easily broken apart with a swift kick of a booted foot or scored by tools commonly made by inmates. 
     U.S. Pat. No. 4,917,395 to Gabriele discloses a wheelchair having a hinge construction between the side panels and seat and back panels uses hinges that are easily disassembled and the molded panels can then be used as weapon parts. Additionally the parts are easily removed to allow for adjustment. Parts that can be removed are neither durable nor safe in this violent environment. 
     U.S. Pat. No. 5,028,065 to Daneker discloses a wheelchair made of foam with adjustable height. This wheelchair does not fold. Foam construction is not durable in a prison environment. The pieces can be easily broken. Prison cells are very small and wheelchairs need to fold so that they can fit inside a jail cell. 
     U.S. Pat. No. 7,182,356 to Haase discloses a wheelchair made of flexible material instead of metal so that it can be wheeled through x-ray metal detectors. This material is easy to tear apart or break and is not durable. Additionally this wheelchair is narrow and cannot accommodate a large individual. 
     U.S. Pat. No. 5,240,276 to Coombs discloses a foldable wheelchair construction with interchangeable right and left panels. The Coombs &#39;276 design offers a simple and inexpensive construction for a wheelchair which may be assembled by relatively unskilled persons and which permits easy repair of broken parts. These parts include left and right side panels and two seat panels which together form the primary structure of the chair. The panels are made of a substantially rigid material, preferably injection molded polymer resin, and are held together in a chair configuration by means of interlocking fasteners. Additional frame stability is achieved by an interlocking pivotable lower support member, and a foldable stay member between the side panels. Wheels are attached in a conventional manner. The wheelchair of the Coombs &#39;276 patent is easy to manufacture into a durable, rigid structure that virtually eliminates the primary causes of structural wheelchair failure, such as frame cracks and broken welds. The entire disclosure of the Coombs &#39;276 patent is incorporated by reference. 
     Despite the highly advantageous features and functions of the wheelchair design(s) disclosed in the Coombs &#39;276 patent, opportunities exist to improve upon features and functions thereof. The present disclosure is directed to Wheelchair design enhancements having particular applicability to wheelchair(s) of the general type disclosed in the Coombs &#39;276 patent. However, the design enhancements of the present disclosure are not limited to the wheelchairs of the Coombs &#39;276 patent, but have wide applicability to wheelchair design and manufacture, as will be apparent to persons skilled in the art. 
     U.S. Pat. No. 7,128,332 to Hermes discloses wheelchair design enhancements. The design enhancements include folding seat panels which are hingedly mounted to the wheelchair frame and offer interlocking functionality. Other design enhancements include pivotal, interlocking footrests and axle plate combinations. The entire disclosure of the Hermes U.S. Pat. No. 7,128,332 is incorporated by reference. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure is directed to wheelchair designs and enhancements thereof that offer advantageous structural and/or functional benefits for wheelchair manufacturers and wheelchair users. The wheelchair designs and associated enhancements disclosed herein include: 1) a wheelchair seat extension panel wherein right/left interchangeable seat extension panels can be added to seat components to accommodate a larger user. The contoured component is identical front and back so that the panels can be reversed to make a complete seat. 2) A wheelchair footrest extension component wherein right/left interchangeable foot rests component panels can be added to footrest components to accommodate a larger user. The said component is identical front to back so that the panels can be reversed to make a complete foot rest. 3) a wheelchair underarm seat extension component wherein right/left interchangeable underarm extension component can be added to seat underarm components to accommodate a larger user. The extension component is identical front and back so that the panels can be reversed to make a complete underarm component. 4) The backrest of an embodiment of the wheelchair is made from a cloth-like material which may be stretched tightly between frame members using Velcro straps fed around buckles. The backrest provides good support without providing pockets or cavities for smuggling contraband. 5) Hinge pins of predetermined length as a means to prevent being used as a weapon, made of a very tough material that resists carving or whittling into a sharp weapon and installed with lock washers that practically precludes the possibility of removing them. 6) Wheelchair components including foot rest and armrests which cannot be removed. 7) Wheelchair components made almost entirely out of hard polymer resins to allow for repeated cleaning with harsh chemicals and even autoclaving to sterilize the wheelchair. 8) Wheelchair components are solid in order to prevent hidden contraband or the manufacture of shooting weapons. 
     Additional structural and functional features and advantages of the disclosed wheelchair designs and associated enhancements will be apparent from the detailed description which follows, taken together with the appended figures. 
     CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefits of a commonly assigned, co-pending provisional patent application entitled wheelchair with security Features which was filed on Aug. 14, 2012 and assigned EFS ID 13491405 and Application Number 61682888. The entire contents of the foregoing provisional patent application are incorporated herein by reference. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those having ordinary skill in the art to which the present disclosure appertains will have a better understanding of how to make and use the wheelchair designs of the present disclosure and enhancements thereof, reference is made to the drawings appended hereto, wherein: 
         FIG. 1  is a perspective view of a wheelchair 
         FIG. 2  is a lateral view of the upper push handle 
         FIG. 3  is a front view of the wheelchair of  FIG. 1   
         FIG. 4  is a lateral, enlarged sectional view of the leg support, side, and armrest 
         FIG. 5  is a plan view of the wheelchair of  FIG. 3  but with the large wheels in the front and the small wheels in the back. 
         FIG. 6  is an enlarged section view of the underarm extension attachment 
         FIG. 7  is an enlarged section view through the seat, along line  115 - 115  in  FIG. 1   
         FIG. 8  is a perspective view of the bariatric underarm extension 
         FIG. 9  is a perspective view of one of the bariatric seat extension pieces of  FIG. 1   
         FIG. 10  is a perspective view of the backrest after it has been folded. It shows 6 buckles and Velcro straps indicating the process of the Velcro strip being inserted into the buckle. 
         FIG. 11  is an opposite-end perspective view of the bariatric extension piece of  FIG. 9   
         FIG. 12  Segmented bariatric seat extension 
         FIG. 13  is a broken away, plan view of a portion (inside the dotted rectangle) of the seat hinge of the wheelchair of  FIG. 5 . 
         FIG. 14  is a perspective view of the backrest of the wheelchair of  FIG. 1  when the backrest is in the fully unfolded, uninstalled position; 
         FIG. 15  is a partially exploded, side view of the hinge rod and the two lock washers of  FIG. 13  with one of the lock washers on its side; 
         FIG. 16  a section view along line  547 - 547  of  FIG. 15 . 
     
    
    
     DESCRIPTION 
       FIGS. 1-16  shows a wheelchair  100  including tamperproof features described in more detail below. The wheelchair  100  is made almost entirely from injection molded polymer resin which is impervious to harsh cleaning and sterilizing chemicals. The wheelchair  100  can be thoroughly cleaned using degreasers live steam, a pressure washer, or may even be autoclaved. 
     The wheelchair  100  is manufactured using substantially identical components for the left and right sides of the wheelchair  100 . For instance, referring to  FIG. 1  left and right side frames  101  are identical molded plastic parts, as are left and right large wheels  103 ; left and right caster wheels  105 ; left and right arm rests  107  (see  FIG. 3 ); left and right leg supports  109 ; left and right foot rests  111 ; left and right seat  113 ; and left and right side bariatric seat extension,  117 ; left and right bariatric foot rest extension  119 ; and left and right bariatric lower arm support extension  303  (see  FIG. 3 ). The bariatric foot rest extension  119  follows the same design and mounting concept as the bariatric seat extension  117  and will not be described in further detail. 
     As best appreciated in  FIG. 3 , square hinge blocks  319  attach the seat extensions  117  to the side frames  101 , respectively of the wheelchair  100 . Inner bariatric seat extension hinges  317 , hingedly connect the seat extensions  117  to the seat  113  respectively of the wheelchair  100 . A mid-seat hinge  305 , connects with a hinge to the seat  113 . Likewise, a foot rest extension hinge  307  attaches the foot rest extensions  119  to the leg support  109  respectively, of the wheelchair  100 . Inner footrest extension hinges  308  hingedly connect to the foot rest extensions  119  to the foot rests  111  respectively, of the wheelchair  100 . Note that there is no mid footrest hinge. Instead, each of the foot rests  111  includes a semi-circular latch  309  which overlaps and cross-latches with the corresponding semi-circular latch. Of the other foot rests  111  such that they separate from each other to fold up and then mutually lock onto support each other when in the extended position shown in  FIG. 3 . 
     Finally a bariatric outer underarm hinge  311  attach the under arm support extensions  303  to the side frames  101 , respectively of the wheelchair  100 . Inner bariatric underarm extension inner hinge  313  hingedly connects the under arm support extension  303  to the under arm support  301  respectively of wheelchair  100 . A mid lower frame support hinge  315  connects with a hinge to the under arm support  301 . 
     As discussed in more detail later all of the hinges mentioned above are manufactured in substantially the same manner to prevent the ability of anyone to use the hinge pins as a weapon. 
     Referring now to  FIG. 9  and  FIG. 11 , the seat extension  117  is a molded polymer body defining a plurality of hinge knuckle projections  909  and recesses  911  extending along its longitudinal dimension along a first side  905 . An opposite side  907  also defines a plurality of projections  901  and a plurality of recesses  911  (see  FIG. 11 ). Unlike the recesses  903  along the first side  905  of the seat extension  117 , the plurality of recesses  911  along the second side  913  do not extend and project through the top surface of the seat extension  117 . The plurality of recesses  911  receives hinge type projections on the corresponding side frame  101 . Since the top portion of the bariatric seat extension  117  above the plurality of recesses  911  abuts the top surface of the hinge type projections of the side frame  101 , the seat extension  117  cannot pivot upwardly along its second side  907  about its axis of attachment  701  (see  FIG. 7 ) relative to the side frame  101 . It should be noted that the bariatric seat extension  117  which is shown as a single molded piece in  FIG. 9  and  FIG. 11  can instead be manufactured as a plurality of segments placed end to end (see  FIG. 12 ). This is schematically illustrated in  FIG. 7  wherein the dotted line  703  shows where two such segments would meet shown in  FIG. 12 . 
     Referring to  FIG. 5  and  FIG. 7 , the seat  113  also defines a plurality of hinge projections  705  and recesses  707  which interlace with the corresponding recesses  903  and projections  901  of the seat extension  117  such that a rod  501  can be inserted through aligned openings  910  ( FIG. 9 ) on the projections  901  of the seat extension  117  and openings  910  (see  FIG. 13 ) on the hinge projections  705  of the seat  113  to form a hinged connection which allows the seat  113  to swing upward in the direction of the arrow  318  (see  FIG. 3 ) so as to fold up the seat and collapse the wheelchair  100  to a stowed configuration. 
     The interlaced projections and recesses are configured so they do not permit the seat portion to pivot in the downward direction beyond a horizontal position. 
     Referring now to  FIG. 11  and  FIG. 13 , the joint between the seat  113  and the bariatric seat extension  117  is pinned together by rods  501  arranged end to end. Each rod  501  is a cylindrical body which is just long enough to span the distance encompassing one hinge knuckle projection  901  of the seat extension  117  and one half each of the two adjacent hinge knuckle projections  705  of the seat  113 . In this embodiment, that distance is approximately 4¼ inches, which is short enough to not lend itself to be used as a weapon, even if it could be removed from the wheelchair. The rod  501  has flat ends and is made from a very hard nylon. It is very difficult to sharpen the end of the rod  501  and create a weapon. Finally, a lock washer  721  is inserted through one of the ends  711  of the rod  501  to lock the rod  501  in place to further prohibit the removal of rod  501 . 
     Referring to  FIG. 15  and  FIG. 16 , the lock washer  721  has an interference fit with the rod  501  such that, when the lock washer  721  is pressed onto the rod  501  in the direction of the arrow  715  (See  FIG. 16 ). The lock washer  721  deforms slightly at lock washer inner diameter  713 . This deformation is enough to lock the washer  721  in place such that it is practically impossible to pull the lock washer  721  back out (in the direction opposite to the arrow  715 ) without destroying the lock washer  721 . The outside diameter of the lock washer  721  is larger than the inside diameter of the aligned openings  910 , and opening  709  through the hinge knuckle projections  901  and  705  which prevents the rod  501  from being removed from the joint once it is installed. In addition, since the rod  501  is recessed (see  FIG. 13 ) inside the hinge knuckle projections ( 901  and  705 ) of the bariatric seat extension  117  and of the seat  113 , it is practically impossible to access the lock washer  721  without cutting or destroying the rod  501 . Thus the joint is made secure so it is very difficult if not impossible to disassemble, and even if it is disassembled, the rods  501  are too short and too tough to be converted for use as weapons. Thus rods  501  and lock washers  721  constitute a means for preventing hinges to be converted to weapons. 
     Very similar short nylon rods  501 , secured at both ends with lock washers  721  are used for all the hinge joints of the wheelchair  100 . This renders the wheelchair  100  tamperproof. Since this is a rod and not a tube, it cannot be used to hide contraband nor be removed to become a shooting weapon. 
     It will also be obvious that eliminating the bariatric seat extensions  117  (see  FIG. 1 ), the bariatric foot rest extensions  119 , and the bariatric under arm support extension  303  (see  FIG. 3 ) results in a standard size wheelchair. In that instance, the seat  113  are connected by hinges directly to the side frames  101  and are able to swing upwardly in the direction of the arrows  318  (see  FIG. 3 ) to fold the standard size wheelchair up for transport or storage. Likewise the footrests  111  are connected by hinges to the leg support  109  and are able to swing in the direction of the dotted arrow  503  (See  FIG. 5 ). 
     Referring now to  FIG. 8  and  FIG. 6  the inner edge  535  of the underarm support extension  303  is placed against an outer edge  539  of the underarm support  301 . Holes  542  are aligned with the holes in the underarm support  301  and small rods  501  with lock washers  721  are installed. Holes  543  are aligned with round pegs  545  and small rods  501  with lock washers  721  are inserted. 
     Referring now to  FIG. 4 , the side frame  101  abuts to leg support  109  and is connected by a plurality of screw and tamper proof nuts through a plurality of holes  549 . Prior to bolting, the screw threads are coated with a liquid to prevent unscrewing. It should be appreciated that one way screws or tamper proof screws could be used instead of tamper proof nut with the same results. This renders the footrest tamper proof since they cannot be removed and used as a battering weapon. 
     Still referring to  FIG. 4 , holes  549  are drilled into the side frame  101  and armrest  107 . Finally the same process of inserting screws, applying adhering liquid and screwing tamper proof nuts onto the screw renders the armrest tamper proof. Additionally all screws and nuts used to attach a brake assembly are applied in an identical fashion. 
     Referring now to  FIG. 2 , each of the side frames  101 , incorporates an upper push handle  505 . The upper push handle  505  defines a plurality of paired, slotted openings  507   a ,  507   b ,  509   a ,  509   b ,  511   a ,  511   b  for securing and releasing the backrest  513  to the wheelchair  100  as described in more detail below. 
     The backrest  513  is made from plastic mesh or similar material which is stretched tightly between the upper push handle  505  using a buckle  517  secured to a webbing strap  518 . Each combination buckle  517  and webbing strap  518  is fed through a corresponding set of paired slotted openings  507   a ,  507   b ,  509   a ,  509   b ,  511   a ,  511   b , then the hook and loop strap  515  is threaded through the buckle and secured back onto itself as described below. 
     Referring to  FIG. 17 , the backrest  513  is a rectangular piece of cloth like plastic mesh material  519  which is folded back onto itself at the fold line  521  to make the substantially rectangular shaped, double-layered backrest  513  shown in  FIG. 10 . It may be noted that the front and rear layers of the double-layered backrest  513  are attached to each other at the fold line  521  which is physically oriented at the top of the backrest  513  when installed onto the upper push handle  505  of the wheelchair  100  as shown in  FIG. 2 . The other three sides of the backrest  513  are totally open so there is no possibility for someone to hide or smuggle contraband between the two layers of the backrest  513 . Any items place between the two layers will simply fall out through the open bottom of the backrest  513 . 
     Referring to  FIG. 14  and  FIG. 10 , it may be appreciated that the plurality of buckles  517  are secured via webbing straps  518  to the rear layer of the backrest  513  while the hook and loop straps  515  are secured to the front layer of the backrest  513  such that when the two layers are folded together as shown in  FIG. 10  each buckle  517  substantially aligns with its corresponding hook and loop strap  515 . (The plurality of buckles  517  and webbing straps  518  could be on the front layer of backrest  513  and the hook and loop straps  515  on the back layer of the backrest  513 ). 
     While the above description contains many specifics, these should not be construed as limitations on the scope of any embodiment, but as exemplifications of various embodiments thereof. 
     It will be obvious to those skilled in the art that various modifications may be made to the embodiment described above without departing from the scope of the invention as claimed.