WHEELCHAIR AND ATTACHMENT THEREFOR

Abstract: An improvement is made in a wheelchair having front caster wheels and rear drive wheels whereby the seated occupant can unaidedly cause the wheelchair to have lateral mobility and can remove the drive wheels. The modification is achieved by jacking apparatus (23) associated with each drive wheel (21). The jacking apparatus has a lever (24) adapted to be moved to a self-locking position which downwardly urges a connecting rod (26), causing telescopic displacement of a rear caster wheel (29). Such downward displacement of the rear caster wheels lifts the rear drive wheels off the underlying support surface.

Description: DESCRIPTION TITLE: WHEELCHAIR AND ATTACHMENT THEREFOR (5) TECHNICAL FIELD This invention concerns improvements in wheelchairs, and more particularly relates to an improved wheelchair wherein the wheelchair-reliant person can without assistance modify the dimensional and mobility charac- (10) teristics of said wheelchair. BACKGROUND ART Wheelchairs are generally constructed having a pair of small forward wheels, each supported by an overhead pivoted yoke which permits the wheel to turn 360° about (15) a vertical axis, and a pair of opposed large rear wheels positioned at each side of the chair on horizontally disposed axles which permit rotation of said rear wheels in fixed vertical planes. The rear wheels, when simul¬ taneously pushed or pulled by the disabled occupant (20) propel the wheelchair in forward or rearward directions. When one rear wheel is pushed more than the other, or when one rear wheel is pushed while the other is maintained motionless or pulled in the reverse direction, the wheelchair can be made to perform turning motions. ~~ (25) One motion however, that the conventional wheelchair is incapable of is a lateral or sideways translational motion in the direction of the horizontal axles of the rear wheels. Such sideways motion is particularly valuable in confined quarters which cannot accommodate ( 30) the size or turning radius of the large rear wheels, and where omnidirectional movement is necessary. Wheelchairs having removable rear wheels have been disclosed in U.S. Patent 4,098,521 and elsewhere. (5) Although removal of the rear wheels substantially converts the wheelchair from a self-propelled to an attendant- propelled state, the feature of optional removability of the rear wheels affords the following advantages: a) easier storage of the wheelchair, particularly in (10) an automobile, b) eliminates the need of the user to lift or be lifted above the top of the rear wheels for side¬ ways transfer from or to the seat which is gener¬ ally below the top of the rear wheels, and (15) c) narrowing of the lateral size of the wheelchair, thereby facilitating passage through narrow aisles. Although U.S. Patent 4,098,521 discloses that the large wheels may be removed while the occupant is in the wheelchair, it is unlikely that this can be accomplished (20) by the occupant without assistance because to do so requires the rearward tilting of the wheelchair to a very precarious position while simultaneously disengaging the large wheels. It is accordingly an object of the present invention (25) to provide a wheelchair having opposed large rear wheels mounted on horizontal axles, said wheels being removable by the seated occupant of said wheelchair. It is a further object to provide a wheelchair of the aforesaid nature wherein said wheels may be safely (30) removed by said occupant unaidedly by the performance of two separate and sequential manipulations. It is another object of this invention to provide a 1 wheelchair capable of motion in the direction of said (5) horizontal axles. It is a further object to provide a wheelchair of the aforesaid nature which, by a single manipulation rapidly achievable by the seated occupant, can be modified so as to have rolling mobility in the direction of said (10) horizontal axles. It is a still further object of this invention to provide apparatus which can be attached to a conventional wheelchair to achieve the foregoing objects. These objects and other objects and advantages of the (15) invention will be apparent from the following description. DISCLOSURE OF INVENTION The above and other beneficial objects and advantages are accomplished in accordance with the present invention by an improvement in an otherwise conventional wheelchair (20) comprised of a frame having paired rear vertical posts, front caster wheels mounted on said frame, seating means associated with said frame generally behind and above said front caster wheels, and a pair of rear drive wheels rotatably supported by said rear vertical posts on oppo- ~ ~ r (25) site sides of said seating means and adapted to rotate in vertical planes about horizontally disposed axles, said drive wheels preferably being equipped with quick discon¬ nect means to facilitate their removal from and return to said wheelchair. ( 30 ) The improvement of the present invention comprises jacking apparatus capable of lifting at least the rear portion of the wheelchair to an elevated height where said drive wheels are no longer resting upon the support (5) surface for said wheelchair, and a pair of rear caster wheels, journalled to said frame in association with said jacking apparatus in a manner to engage said support surface when the rear portion of the wheelchair is lifted. The jacking apparatus is preferably associated with the (10) axles of said drive wheels. Lever components of said jacking apparatus are situated within reach of the occu¬ pant seated in the wheelchair, and are adapted for movement in a substantially vertical plane to cause the jacking apparatus to raise or lower the rear caster (15) wheels, whereby the rear portion of t-he wheelchair is respectively lowered or raised. In a preferred embodiment, the rear caster wheels are telescopically engaged with the frame in a downwardly directed manner such that, when not in operative position, (20) the distance between the center of the drive wheel axle and the lowermost portion of an associated rear caster wheel is less than the radius of the drive wheel. In such non-operative or standby position, the rear caster wheels do not contact the support surface. When placed in ( 25 ) operational position by means of said levers, the distance between the center of the drive wheel axle and lowermost portion of the associated rear caster wheels becomes greater than the radius of the drive wheels, thereby causing the lowermost portions of the drive wheels to (30) rise from contact with the support surface. The wheelchair may be of a conventional foldable construction, and said seating means may have flexible seatrest and backrest portions. Removable foot and leg (5) supports may be associated with the forward end of the wheelchair. Armrest members may be associated with said seating means, and clothing protectors may be vertically disposed between said armrest members and the lowermost extremity of said seating means. A circular handrail (10) may be coaxially disposed about each of said drive wheels to facilitate their manipulation. The term caster wheel, as employed herein, is intended to denote a wheel pivotably mounted from above in a manner permitting rotation in a vertical plane and (15) 360° of turning about a vertical-.axis. The manner of mounting generally involves a yoke which spans said wheel in engagement with opposite extremities of the wheel's horizontally disposed axle, and pivotably engages an overhead support. In the preferred embodiment of the (20) improved wheelchair of the present invention, when the rear caster wheels are activated to support the wheel¬ chair, said wheelchair is capable of movement in any direction whether or not the drive wheels are removed because it is supported by four caster wheels. In such r- - ~ - (25) state, movement of the wheelchair is accomplished by the occupant by applying pulling or pushing force to nearby objects such as walls in a confined area. The lever-operated jacking apparatus may be installed onto newly manufactured wheelchairs designed to accommo- (30) date said jacking apparatus, or said jacking apparatus, with slight structural modification, may be adapted for installation onto existing conventional wheelchairs. BRIEF DESCRIPTION OF DRAWINGS (5) For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing forming a part of this specification and in which similar numerals of reference indicate (10) corresponding parts in all the figures of the drawing: Figure 1 is a rear perspective view of a wheelchair equipped with an embodiment of jacking apparatus of the present invention, showing said wheelchair in its upwardly jacked position. (15) Figure 2 is an enlarged fragmentary sectional view taken along the line 2-2 of Figure 1, showing the wheel¬ chair in its upwardly jacked position. Figure 3 is an enlarged fragmentary side view taken along the* line 3-3 of Figure 1 with the drive wheel (20) removed and showing the wheelchair in its lower, u jacked position. Figure 4 is a side view taken along the line 4-4 of Figure 2. Figure 5 is an enlarged sectional view taken along (25) the line 5-5 of Figure 1. BEST MODE OF CARRYING OUT THE INVENTION Referring to Figure 1, a wheelchair is shown comprised of a metal tubular frame 10 having paired front vertical posts 11 and paired rear vertical posts 12. (30) Diagonal support members 13 extending between lower horizontal connecting members 15 and upper horizontal connecting members 16 of frame 10 are interengaged by pivot pin 14 which enables the wheelchair to undergo a (5) folding-type motion causing lateral compaction thereof. Front caster wheels 17 engage the lowermost extremities of front vertical posts 11. Situated rearward and above front caster wheels 17 is seating means 20 comprised of back sling 18 and seat sling 19 fabricated of compliant (10) web-like materials and supported by portions of said frame. A pair of spoked rear drive wheels 21 having horizontally disposed hubs 22 and associated axles 30 are adapted for rotation in vertical planes about said axles. A lever-operated jacking device 23 is associated (15) with each rear vertical post 12 on the innermost or facing sides of said posts. The exemplified embodiment of jacking device shown in detail in Figures 2-4 is designed to be applied as an accessory feature to conven¬ tional wheelchairs. Said jacking device is comprised of (20) a support bracket 31 adapted to be fastened to post 12 by bolt 32 which penetrates channel 33 in said post and is secured by thread in bracket 31. A buttressing protru¬ sion 43 affixed to bracket 31 engages post 12 to prevent rotation of said bracket about bolt 32. An axle housing ( 25 ) 35 in said bracket disposed within protrusion 43 and parallel to channel 33 is adapted to provide journalled support for axle 30 of drive wheel 21. A lever 24 is attached to bracket 31 by first pivot means 25, thereby permitting pivotal movement of said lever in a vertical ( 30 ) plane. The forward ost portion of said lever is f OMPI designated action portion 44, and the rearwardmost portion of said lever is designated handle 39. A vertical connecting rod 26 is pendantly attached by a (5) second pivot means comprised of bushing 47 and pin 40 attached to said lever in action portion 44. The lower¬ most extremity of said vertical connecting rod engages a third pivot means comprised of bushing 46 and horizon¬ tally disposed pin 27 attached to column 28 which (10) supports rear caster wheel 29. Column 28 is adapted to telescopically engage tubular housing 30 pendantly supported by sleeve 37 fitted onto horizontal connecting member 15 and joined thereto by bolts 38. In the illustrated embodiment, connecting rod 26 is (15) shown to be of adjustable length by virtue of upper and lower threaded engagement means 41 and 42 respectively associated with bushings 47 and 46, and which possess opposite threading and thereby enable connecting rod 26 to function in a turnbuckle manner when rotated about its (20) long axis. To facilitate such rotation, said connecting rod may be provided with a knurled surface. When the jacking device is activated to cause lift¬ ing, lever 24 will be in a substantially horizontal position, as shown in Figure 2. In said position, it is ( 25 ) important to note that first pivot means 25 is above second pivot means 40, and the lever is in abutment with the innermost extremity of axle housing 35 which emerges from the inside face 45 of buttressing protrusion 43. Such manner of abutment prevents further downward movement ( 30 ) of handle portion 39. The position of the second pivot means with respect to the first pivot means, and the angle of connecting rod 26 between said second and third pivot means are such that forces directed upwardly from (5) rear caster wheel 29 urge lever 24 in the direction of abutment with axle housing 35. Such factors of design and construction thereby constitute locking means which concertively act to maintain lever 24 in a fixed hori¬ zontal position. The elements of said locking means (10) comprise an abutment means such as axle housing 35, and a force emanating from rear caster wheel 29 and trans¬ mitted to said second pivot means in a manner serving to pivot said lever about said first pivot means in the direction of said abutment means. Properly directed force (15) transmission to the second pivot means may be secured by either proper placement of the second pivot means with respect to the first pivot means, or proper angle of the connecting rod. The distance of separation between the centers of (20) said first and second pivot means is essentially the distance between the uppermost and lowermost positions of the rear caster wheel. It is to be noted that, when lever 24 is in its upright position as shown in Figure 3, first and second pivot means are centered on a substan- (25) tially horizontal line. Although the invention has been exemplified primarily in terms of an embodiment wherein the jacking apparatus may be added to an existing conventional wheelchair, it is to be understood that the same inventive principles ( 30 ) may be applied to a wheelchair specifically manufactured PI to incorporate the features of the jacking apparatus herein described. In said latter instance, the rear caster wheel, instead of being mounted on a sleeve-like (5) fitting adapted to fit onto the lower horizontal connecting member, may be telescopiσally fitted to an extension of rear vertical post 12 below said lower horizontal connecting member. Furthermore, certain features of the bracket member may be incorporated into (10) vertical post 12. In any embodiment of the jacking apparatus of this invention, it is preferable to locate the rear caster wheel no closer to the front of the wheel¬ chair than the axles of said drive wheels, the reason being to prevent the wheelchair from toppling over (15) rearwardly. Braking means, operable by the seated occupant of the wheelchair may be provided to afford greater control over the motion of the wheelchair when it is in its jacked-up mode and capable of omnidirectional movement. (20) Such braking means may be lever-activated devices which cause frictional restraint between the frame and the ground or rear caster wheels. The quickly detachable drive wheels utilized in the preferred embodiment of wheelchair of the present inven- (25) tion are of standard manufacture. In Figure 5, which schematically illustrates the general features of a detachable drive wheel, a sliding rod 50 positioned within channel 51 i "axle 30 rests in abutment with untensioned spring 52 confined in the closed end 53 of (30) axle 30. A detent 54 which extends outwardly from axle 30 and communicates with channel 51 is associated with a tensioned spring 55 which maintains a force on detent 54 tending to draw it inwardly toward channel 51. The inner (5) end of said detent is normally in abutment with the cylindrical surface of rod 50, said abutment causing the outer end of said detent to protrude from axle 30. However, when rod 50 is pressed toward the closed end of axle 30, a depressed portion 56 is brought beneath (10) detent 54. Such action causes detent 54 to temporarily enter axle 30,- thereby releasing axle 30 and its asso¬ ciated drive wheel from fixed engagement with axle housing 35. While particular examples of the present invention (15) have been shown and described, it is apparent that changes and modifications may be made therein without departing from the invention in its broadest aspects. The aim of the appended claims, therefore, is to cover all such changes and modifications as fall within the true (20) spirit and scope of the invention. (25) (30) O PI

Claims: CLAIMS 1. In a wheelchair comprised of a frame having paired front and rear vertical posts which define an interior (5) region of said frame and paired upper and lower hori¬ zontal connecting means extending between front and rear posts, paired front caster wheels mounted on said frame adjacent said front posts, seating means disposed within said interior region generally behind (10) and above said front caster wheels, and a pair of rear drive wheels rotatably supported by said rear vertical posts on the exterior of said frame on opposite sides of said seating means and adapted to rotate in vertical planes about horizontally disposed (15) axles, said front caster and rear drive wheels being adapted to support said wheelchair at four sites for rolling motion upon an underlying substantially planar support surface, the improvement comprising jacking apparatus associated with each rear vertical post, (20) said apparatus being comprised of a rear caster wheel which engages said frame in a manner to be vertically positionable between uppermost and lowermost positions, a lever haying an active portion, and a handle portion posi- (25) tioned within reach of a seated occupant of said wheelchair, said active portion being associated with said frame by first pivot means permitting about 90° of movement of said lever in a vertical plane between upright and horizontally disposed ( 30) positions, vertical connecting means having an O PI upper extremity attached by second pivot means to said action portion and a lower extremity associated by third pivot means with said caster (5) wheel, and locking means which act to cause said lever to be maintained in said horizontal disposition, whereby when said lever is in its horizontally disposed position, said rear caster wheel is displaced (10) ' downwardly by said connecting means to its lower¬ most position, and when said lever is in its upright position, said rear caster wheel is in its uppermost position, said lowermost position of said rear caster wheel being such as to cause (15) the associated drive wheel to be lifted out of contact with the support surface while placing said rear caster wheel in contact with said support surface. 2. The wheelchair of claim 1 wherein said drive wheels (20) are equipped with quick disconnect means to facili¬ tate their removal from and return to said frame. 3. The wheelchair of claim 1 wherein said jacking apparatus is located substantially within the interior region of said frame. (25) 4. The wheelchair of claim 1 wherein the distance between said first and second pivot means is substantially equal to the distance between the uppermost and lower¬ most positions of said rear caster wheel. 5. The wheelchair of claim 1 wherein said second pivot (30) means is below said first pivot means when said lever is in its horizontally disposed position. 6. The wheelchair of claim 5 wherein said second pivot means is centered slightly forwardly of the center (5) of said first pivot means when said lever is in its horizontally disposed position. 7. The wheelchair of claim 1 wherein said rear caster wheel is located below the lower horizontal connecting means of said frame. (10) 8. Apparatus adapted for attachment to a wheelchair having a frame having rear vertical posts, said apparatus comprising a caster wheel adapted for attachment to said frame and vertically positionable between uppermost and lowermost positions, a bracket (15) adapted for attachment to one of said posts, a lever having an active portion and a handle portion, said active portion being connected to said bracket by first pivot means permitting about 90° of movement of said lever in a vertical plane between upright and (20) horizontally disposed positions, connecting means having an upper extremity attached by second pivot means to said action portion and a lower extremity associated by third pivot means with said caster wheel, and locking means which act to cause said lever (25) to be maintained in said horizontal disposition, whereby when said lever is in its horizontally disposed position, said caster wheel is displaced downwardly by said connecting means to its lowermost position, and when said lever is in its upright posi- (30) tion, said caster wheel is in its uppermost position. 9. The apparatus of claim 8 wherein said bracket has an axle housing. 10. The apparatus of claim 8 wherein said connecting means (5) are of adjustable length. 11. In a wheelchair which " includes: a frame, including a seating means for a person disposed thereon; a front and a rear pair of wheels for supporting (10) the wheelchair on a flat surface, the wheels of each pair being laterally spaced from one another and journalled to the frame for rotation about a hori¬ zontal axis; a first one of said pairs of wheels being rela- (15) tively small-diameter wheels which are journalled to the frame by respective journalling means constructed and arranged to permit relatively omnidirectional horizontal travel of the wheelchair upon the flat surface; (20) the second one of these pairs of wheels being relatively large-diameter wheels positioned within generally convenient hand-reach of a person occupying said seating means, so as to function as drive wheels, and journalled to the frame by journalling means (25) constructed and arranged to permit rotation of the drive wheels about the aforesaid horizontal axis; the improvement wherein the wheelchair is further provided with: a third pair of wheels of relatively small ( 30 ) diameter constructed and arranged to permit relatively / OMPI omnidirectional horizontal travel of the wheelchair upon the flat surface; means journalling the wheels of the third pair (5) to the frame at opposed sites near where the wheels of the second pair usually engage the flat surface; means for vertically adjustably disposing the wheels of the third pair between: an upper location wherein respective sites (10) where the wheels of the third pair would engage the flat surface are located substantially above the level of the respective sites where the wheels of the second pair usually engage the flat surface, so that the wheelchair is supported upon (15) the first and second pairs of wheels but not upon the third pair of wheels, and a lower location wherein the respective sites where the wheels of the third pair would engage the flat surface are located substantially below (20) the level of the respective sites where the wheels of the second pair usually engage the flat surface so that the wheelchair is supported upon the first and third pairs of wheels but- not upon the second pair of wheels; ( 25) said means for vertically adjustably disposing the wheels of the third pair comprising actuator means positioned within generally convenient hand-reach of the person occupying the seating means of the wheel¬ chair; and linkage means connected between the actuator ( 30 ) means and the means for journalling the third pair of wheels to the frame, the linkage means being con¬ structed and arranged to cause the wheels of said third pair to be moved from said upper location to (5) said lower location and from said lower location to said upper location upon respective manipulation of said actuator means by the person occupying the seating means of the wheelchair, whereby the wheel¬ chair may be switched back and forth by said person - (10) between a first mode wherein the person can use the wheels of the second pair to propel the chair, but cannot move the chair laterally in the direction of said horizontal axes, and a second mode wherein the person can move the chair essentially omnidirec- (15) tionall but cannot use the wheels of the second pair to propel the chair. 12. Apparatus for attachment to a wheelchair, which wheel¬ chair includes: a frame, including a seating means for a person (20) disposed thereon; a front and rear pair of wheels for supporting the wheelchair on a flat surface, the wheels of each, pair being laterally spaced from one another and journalled to the frame for rotation about a hori- (25) zontal axis; a first one of these pairs of wheels being relatively small-diameter wheels which, though out of generally convenient hand-reach of a person occupying the seating means of the wheelchair are journalled ( 30 ) to the frame by respective journalling means which are constructed and arranged to permit relatively omni¬ directional horizontal travel of the wheelchair upon the flat surface; (5) the second one of these pairs of wheels being relatively large-diameter wheels- which, though posi¬ tioned within generally convenient hand-reach of a person occupying the seating means of the wheelchair, so as to function as drive wheels, are journalled to (10) the frame by respective journalling means which are constructed and arranged to permit rotation of the respective drive wheels about the respective afore¬ said horizontal axis with this axis constrained to extend transversely of the chair, (15) said apparatus comprising: a third pair of wheels; means for journalling the wheels of the third pair to the frame at respective sites near where the wheels of the second pair usually engage the flat (20) surface; the wheels of the third pair being relatively small-diameter wheels which, though out of generally convenient hand-reach of the person occupying the seating means of the wheelchair, said journalling (25) means for said third pair are constructed and arranged to permit relatively omnidirectional hori¬ zontal travel of the wheelchair upon the flat surface; the means for journalling the third pair of wheels to the frame including means for vertically (30) adjustably disposing the wheels of the third pair between : an upper location wherein respective sites where the wheels of the third pair would engage (5) the flat surface are located substantially above the level of the respective sites where the wheels of the second pair usually engage the flat surface, so that the wheelchair is supported upon the first and second pairs of wheels but not (10) on the third pair of wheels, and a lower location wherein the respective site where the wheels of the third pair would engage the flat surface are located substantially below the level of the respective sites where the (15) wheels of the second pair usually engage the flat surface, so that the wheelchair is supported upon the first and third pairs of wheels but not on the second pair of wheels; person-powered operator means for the journal- (20) ling means of the third pair of wheels, this operator means including: actuator means adapted to be positioned within generally convenient hand-reach of the person occupy¬ ing the seating means of the wheelchair; and linkage (25) means connected between the actuator means and the means for journalling the third pair of wheels to the frame, the linkage means being constructed and arranged to cause the wheels of said third pair to be moved from said upper location to said lower loca- (30) tion and from said lower location to said upper location upon respective manipulation of said actuator means by the person occupying the seating means of the wheelchair, whereby the wheelchair may be switched (5) back and forth by the person occupying the seating means thereof between a first mode wherein the person can use the wheels of the second pair to propel the chair, but cannot move the chair laterally in the direction of said horizontal axes, and a second mode (10) wherein the person can move the chair essentially omnidirectionally, but cannot use the wheels of the second pair to propel the chair; and means for mounting said apparatus to said frame. (15) (20) (25) (30)

Inventors: CHRISTIAN DIXON W
Applicants: CHRISTIAN DIXON W
Application year: 1982
Main classification: B62M1
IPC codes: A61G5