Abstract:
A locking anti-theft device operates between any paired collapsedly opposed members of a folding wheelchair to selectively prevent folding. Each end of the anti-theft device is attached, either permanently or removably, to any paired collapsedly opposed members of the wheelchair such that when the device is in the locked position the central pivot point, about which the left and right portion of the device are pivotally attached, is restricted from pivoting thus preventing the wheelchair from folding.

Description:
FIELD OF THE INVENTION 
     The invention relates to an adjustable anti-theft device for use primarily with wheelchairs of the folding variety, however, this adjustable anti-theft device may be suitable for use with other types of folding apparatuses as well. 
     BACKGROUND OF THE INVENTION 
     Wheelchairs are relatively expensive devices costing thousands of dollars in some cases. They generally come in two varieties—folding and non-folding types. The folding variety is susceptible to an increasing amount of theft because of their high value and the ease with which some can be folded, stored and carried off. As one might expect, the incidence of theft of non-folding wheelchairs is substantially less. 
     Many hospitals, nursing homes, rest homes and similar facilities are experiencing ever increasing costs due to the loss of folding wheelchairs. Most wheelchairs utilized in the aforementioned facilities are of a conventional folding type. Consequently, these wheelchairs are capable of being easily folded and inadvertently carried off by patients&#39; family or deliberately stolen by folding them and putting them in the trunk of a car. 
     The prior art, U.S. Pat. No. 5,149,120, also discloses a locking mechanism which may be designed into the wheelchair at the time of manufacture or which may be added later as in the present invention. However, said prior art prohibits a folding wheelchair from being folded by restricting a pair of centrally pivoted cross braces under the wheelchair seat which move from an X-shaped configuration to a more parallel configuration when the wheelchair is being folded. This mechanism is difficult to reach and to operate and particularly presents a problem when the wheelchair user is unassisted in the locking and securing the anti-theft device. 
     By being able to selectively restrict a folding wheelchair from folding, some of the aforementioned theft could be avoided. Consequently, there is a market demand for an inexpensive anti-theft device that can be designed into newly manufactured wheelchairs or, alternatively, easily fitted to existing folding wheelchairs which selectively prohibits them from folding when they are used and allows them to be folded and stored when they are not being used. 
     Therefore, the several objects of the present invention are to provide an improved wheelchair with an anti-theft device, the location of which is easily accessible making for easy locking and unlocking. It is another object of the invention to provide an easily accessible anti-theft device for use with wheelchairs and other folding apparatuses. It is another object of the invention to permit usability on many types of folding wheelchairs, not just those types that have an X-shaped folding cross-member configuration as in the prior art. It is another object of the invention to permit alternative placement of the anti-theft device, both in the front and at the rear of the folding wheelchair or between many of the pairs of vertical or horizontal collapsedly opposed structural members of the wheelchair. Furthermore, it is an object of the present invention to provide a low cost solution to a high cost problem. 
     SUMMARY OF THE INVENTION 
     The present invention is an anti-theft device primarily for use with a folding wheelchair operated by selectively preventing folding of the wheelchair when the anti-theft device is engaged. This is accomplished by preventing from folding, any pair of collapsedly opposing members comprising a portion of the chassis of the folding wheelchair that collapse toward one another when the wheelchair is being folded. 
     A left member and a right member of the anti-theft device are pivotally attached to said pair of collapsedly opposing members of the folding wheelchair by an attachment means. Said left and right members overlap and are pivotally connected to one another by a pivotal attachment means. A locking mechanism selectively prevents the left and right members from pivoting relative to one another about the pivotal attachment means, thus preventing the wheelchair from folding. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects of this invention, the various features thereof, as well as the invention itself, may be more fully understood from the following description, when read together with the accompanying drawings, described: 
     FIG. 1 is a partial perspective view illustrating a collapsible wheelchair of a type to which the anti-theft device of the present invention may be applied; 
     FIG. 2 is a front view of the anti-theft device in accordance with the present invention; 
     FIG. 3 is a front view of the anti-theft device shown in FIG. 2 as applied to two collapsedly opposing members of the folding wheelchair of FIG. 1; 
     FIG. 4 is the side view of a type of locking mechanism of the anti-theft device shown in FIG.  2 . 
    
    
     For the most part, and as will be apparent when referring to the figures, when an item is used unchanged in more than one figure, it is identified by the same alphanumeric reference indicator in all figures. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a collapsible apparatus, namely, a wheelchair of the general type to which the anti-theft device in accordance with the present invention may be applied. 
     As shown in FIG. 1, the wheelchair frame, referred to generally by the reference numeral  10 , includes tubular members adapted for folding and unfolding movement to transition between an expanded configuration for normal wheelchair use and a collapsed configuration for facilitated transport and/or storage. 
     The general construction of the illustrative wheelchair frame  10  is representative of lightweight folding wheelchair frames formed predominantly from metal tubing members. Those skilled in the art will appreciate that the wheelchair frame of FIG. 1 is only one of many possibilities and the present invention is not meant to be limited by this representation. More particularly, the wheelchair  10  conventionally includes left and right side frames  12  and  14  each of which includes means for supporting a relatively large main rear wheel  16  and a relatively small front caster wheel  18 . While the main rear wheels  16  rotate in substantially fixed parallel planes orthogonal (i.e., vertical) to a ground surface upon which the wheelchair moves, each caster wheel  18  is capable of rotating 360 degrees with respect to an axis orthogonal to the ground surface. As a result, the wheelchair is capable of superior maneuverability in tight quarters. The side frames  12  and  14  respectively include horizontally extending upper side rails  22  and  24 , horizontally extending lower side rails  26  and  28 , vertically extending rear side rails  30  and  32 , vertically extending middle side rails  34  and  36 , and vertically extending front side rails  38  and  40 . A folding seat  20 , such as a sling seat of the like, extends between upper side rails  22  and  24 . Arm rests  42  and push handles  44  are normally provided at or near the upper end of the seat-back posts  46  and  48 , all in a well-known manner to one skilled in the art. A cross brace unit  52  is connected between the side frames  12  and  14  to provide a movable support structure accommodating folding movement of the side frames between the expanded and collapsed positions. 
     The aforementioned left and right side frames  12  and  14 , including upper side rails  22  and  24 , lower side rails  26  and  28 , rear side rails  30  and  32 , middle side rails  34  and  36 , front side rails  38  and  40 , and seat back posts  46  and  48  are of the type which may be considered as collapsedly opposing. 
     An exploded view of a preferred embodiment of the adjustable anti-theft device  54  the present invention is shown in FIG.  2  and includes a left member  56 , a night member  58  and a locking mechanism  60 . The adjustable anti-theft device  54  shown in FIG. 2 is not attached to a wheelchair, but may be either integral with the frame (e.g., incorporated at the production stage) or attachable and removable to any one of a number of wheelchairs. As illustrated in detail in FIGS. 2,  3 , and  4 , the left member  56  and right member  58  of the anti-theft device are pivotally attached via a first tubular grip  67  and a second grip  68  to a pair of collapsedly opposing members  32  and  30 ; etc. of the wheelchair. By way of illustration and not limitation the first and second tubular grips may take the form of pivotable circular clamps. Such attachments may be made to numerous placements on pairs of collapsedly opposing members, however, optimal placement may be attained when left member  56  and right member  58  are pivotally attached to rear side rails  30  and  32  for ease of access when locking and unlocking the anti-theft device. It should be understood that there are numerous possible placements for anti-theft device  54  and this detailed description does not attempt to demonstrate or include all possible placements. 
     FIG. 3 shows the preferred embodiment of anti-theft device  54 , shown attached to a pair of vertically opposed members  30  and  32 . Anti-theft device  54  can alternatively be attached to other such collapsedly opposed members, including horizontally opposed members such as  26  and  28 . 
     In more detail, said left portion  56  and said right portion  58  are constructed of a durable material such as solid aluminum. Said left portion  56  contains multiple horizontal slots  62  spatially placed for size adjustment to fit between the paired collapsible members of the wheelchair, said slot placement being dependent on the design of the particular wheelchair. Said left portion  56  and right portion  58  overlap and are pivotally connected by an attachment means  64 . The locking means  60  of the anti-theft device  54  is of the type that may be permanently affixed to the body of the right portion  58 , the body of the left portion  56 , or may be of a stand alone type. The locking means  60  is of the type that prevents the left portion  56  and right portion  58  from pivoting relative to one another about the pivotally connecting attachment means  64 . FIGS. 2,  3 , and  4  show the use of a standard pushpin type of lock  60  (e.g., a gun cabinet lock) in the preferred embodiment. When locking mechanism  60  is engaged as shown in FIG. 4 b,  left portion  56  and right portion  58  are prevented from pivoting relative to one another about attachment means  64 , thus preventing the wheelchair from folding. When the locking means  60  is disengaged, as shown in FIG. 4 a,  the left portion  56  and right portion  58  are collapsible such that the left portion  56  and right portion  58  pivot about hinge pin  64 , and in accordance with pivot lip  66 , induce the left portion  56  and right portion  58  to rotate about the pivotally connecting attachment means in an inverted “V” configuration. 
     The invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. As various changes could be made in the above constructions without departing from the scope of the present invention, it should be understood that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by appending claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. 
     In the preferred embodiment, pivot lip  66  may be affixed to the upper edge of right member  58  such that pivot lip  66  extends across the width of left member  58  and right member  56  to restrict directional folding of the anti-theft device  54  to an upward folding direction as shown in FIG. 2 b.  Alternatively, pivot lip  66  may be affixed to the lower edge of the left portion  56  such that pivot lip  66  extends across the width of right member  56  and left member  58  to restrict directional folding of the anti-theft device  54  to an upward folding direction. The pivot lip  66  may be strategically placed to restrict the folding to a downward direction or no pivot lip  66  may be used at all.