Abstract:
Knee-walkers allow amputees and individuals with injuries to maintain independent movement. Their stability and steering is very important. The invention comprises a knee-walker ( 10 ) comprising a frame ( 20 ), at least two ground-engaging wheels ( 50 ) at the front, a seat ( 90 ), a steering column ( 70 ), and a steering belt ( 200 ) linking the steering column to the two front wheels, the two front wheels being steered by rotation of the steering column and consequent rotation of the belt.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to a knee-walker and finds particular, although not exclusive, utility in supporting the leg of an individual during convalescence. 
     BACKGROUND OF THE INVENTION 
     In situations where an individual has damaged, or had a surgical procedure on, an ankle or foot it is preferred medically to keep weight off the foot or ankle while recuperating. Traditionally, this has been achieved by the use of wheelchairs or crutches. However, wheelchairs can be undesirable for many reasons such as access. Also, not everyone is able to use crutches due to the possibility of weakness or inconvenience. Accordingly, a device known as a “knee-walker” has been developed in the past to support the injured leg while providing stability such that the individual may still move around on their own. Such knee-walkers are known from U.S. Pat. No. 4,867,188, U.S. Pat. No. 5,800,317 and U.S. Pat. No. 7,311,319. With regard to these prior art devices, they all have certain deficiencies such as the inability to steer them effectively, especially on uneven terrain, and instability. Accordingly, it is desirable to have an improved knee-walker. 
     BRIEF SUMMARY OF THE INVENTION 
     The knee-walker may also be useful for amputees. 
     In one aspect, the invention provides a knee-walker comprising a frame, at least two ground-engaging wheels at the front, a seat, a steering column, and a steering belt linking the steering column to the two front wheels, the two front wheels configured to be steered in response to rotation of the steering column and consequent rotation of the belt. 
     The knee-walker may also be known as a mobility walking support aid. Each front wheels is pivotable relative to the frame about a vertical axis. 
     In use, an individual may rest a knee on the seat and grasp the steering column via handlebars attached thereto to thereby steer the knee-walker. The steering belt enables no loss of steering even on uneven terrain, because both front wheels are steered simultaneously. 
     The term “belt” may also include other bands such as chains, ropes, cords, and similar flexible yet substantially inextensible continuous loops. 
     The knee-walker may further comprise belt pulley tensioners for adjusting the tension in the belt. These may take the form of pulley wheels around which the belt may fit. 
     The belt tensioner pulleys may change the angle of the belt by more than 90 degrees from one side of the belt tensioner to the other side. This may allow for a wrap angle of greater than 90 degrees enabling effective tensioning. 
     The belt may have teeth and each of the two front wheels may include toothed drive cogs for engagement by the toothed belt. Alternatively a smooth belt may be employed with no toothed cogs. The two front wheels include guides for the belt. The guides may be the toothed drive cogs. The belt may wrap around, and thus contact with, each guide for more than half of its circumference. This enables effective steering and reduces the chance of slipping especially with smooth (non-toothed) belts. 
     The centre of rotation of the steering column may be off-set from an imaginary line drawn between the centre of rotation of each of the front wheels. The steering column may be forward of this imaginary lines such that each front wheel is behind the steering column. This allows for a reduced turning circle. In fact, in one embodiment, the knee-walker may turn through 90 degrees with a turning circle of approximately 1027 mm. 
     The knee-walker may further include two rear wheels approximately at each rear corner of the frame. Each rear wheel may be fixed about a vertical axis such that each is non-pivotable about its respective vertical axis. However, in one embodiment it is possible that the rear wheels are also freely pivotable about a vertical axis. 
     The frame may comprise two side members extending from one end of the knee-walker to the other and a front cross member provided at one end of the two side members, the front cross member may accommodate the steering column and the two front wheels; the rear wheels may be supported on an axle arranged between the two side members at the other end of the two side members. 
     The side members may include a pivot about which each side member is foldable such that the rear wheels may be movable towards the front wheels so that the volume required to accommodate the knee-walker may be reducible for storage when not in use. This allows less packaging than otherwise as well as ease of storage. 
     The knee-walker may further comprise a handle for locking and unlocking the side members such that the side members are foldable. The handle may be lifted to unlock the side members and pushed down to lock them relative to one another. In another embodiment, the handle may be attached to a spring-biased pin cooperating directly with the pivot on one of the side members. 
     The seat may comprise a seat pad and a dependent seat post for adjustably fixing the seat to the frame, wherein the seat pad may be offset relative to the seat post such that it may be asymmetrical relative to the seat post so that in use the seat pad may be alignable to the left or the right of an imaginary centre line of the knee-walker for accommodating a left or right knee. In this regard, the centre line may extend from between the two front wheels to between the two rear wheels. The seat pad may thus extend more towards the right or left of the centre line. 
     At least some of the wheels may include suspension. This may take the form of coil springs, leaf springs or other such resilient members. The suspension may allow for a smoother “ride” for the individual which may be important to prevent jarring of the injury. It also allows for the front wheels to maintain traction with the ground at all times. 
     The amount of vertical “play” in the suspension may be 20 mm in one or both directions. 
     The steering column may include a pivot point for folding the steering column down when not in use. This may take the form of opposing teeth provided on opposing members each rotatable relative to the other one and releasably lockable to one another by means of a clamping mechanism. 
     The steering column may be removably attachable to the frame. This may allow it to be removed during storage. The removability may be effected, for example, by the two opposing members being completely disengagable with one another. Alternatively, or additionally, the steering column may be removably attachable from the front cross-member. 
     The knee-walker may include at least one brake. This may be controlled by a lever mounted on the steering column and/or the handlebars attached thereto, connected to the brake by a control wire in a similar manner to that found on bicycles. 
     The brakes may be rear disc brakes. The brake may be a parking brake. Alternatively a parking brake may be provided in addition to the disc brakes. 
     The steering column may be lockable in position such that it cannot rotate about its longitudinal axis. This may be provided by a pin extendable and retractable through a hole provided in a socket in which the steering column connects to the front cross member and a corresponding pin-receiving hole provided in the steering column. To lock the steering column the pin is extended through the hole into the pin-receiving hole such that the steering column cannot rotate relative to the socket provided on the front cross-member. However, other ways of locking the steering column are contemplated such as a clamp. 
     The knee-walker may be collapsible or foldable to reduce its volume during period of non-use. 
     The steering of both front wheels simultaneously may permit a sharp angled (for example 90 degrees) turn to be effected with no loss of stability. Steering may be more finely controlled than with only one wheel being steered, especially on slopes or uneven ground. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings. 
         FIG. 1  is a perspective view of a knee-walker according to one embodiment of the invention; 
         FIG. 2  is a different perspective view of the knee-walker of  FIG. 1 ; 
         FIG. 3  is a an elevational side view of the knee-walker of  FIGS. 1 and 2 ; 
         FIG. 4  is a front elevational view of the knee-walker of  FIGS. 1 to 3 ; 
         FIG. 5  is a side elevational view of the knee-walker of  FIGS. 1 to 4  in a collapsed or folded state; 
         FIG. 6  is an underside view of the front of the knee-walker of  FIGS. 1 to 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention. 
     Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. 
     Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein. 
     It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B. 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may refer to different embodiments. Furthermore, the particular features, structures or characteristics of any embodiment or aspect of the invention may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments. 
     Similarly it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention. 
     Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination. 
     In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description. 
     In the discussion of the invention, unless stated to the contrary, the disclosure of alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less preferred value and said intermediate value. 
     The use of the term “at least one” may, in some embodiments, mean only one. 
     The invention will now be described by a detailed description of several embodiments of the invention. It is clear that other embodiments of the invention can be configured according to the knowledge of persons skilled in the art without departing from the true spirit or technical teaching of the invention, the invention being limited only by the terms of the appended claims. 
     In  FIG. 1  the knee-walker  10  is shown comprising a frame  20  made of tubular bars having an oval shape cross-section. The frame  20  comprises a front cross-member  40  and two side members  30  extending rearwardly from the front cross-member  40 . At the rear of the walker an axle  110  is provided on which two rear wheels  120  are arranged. The rear wheel arrangement may be such that a split bearing is provided with the axle  110 . 
     The front cross-member  40  supports two front wheels  50  arranged at each end thereof. The front wheels  50  are pivotable to the front cross-member  40  such that they may each rotate about a respective vertical axis. Each front wheel is supported on the cross member  40  and includes a wheel pulley  210  about which a belt  200  passes. The rotation of the wheel pulley  210  induces rotation of the wheel  50 . The belt  200  allows for steering of the front wheels  50  as will be described in more detail below. The front cross-member  40  includes swept-back arms at each end of a substantially straight central section. It is at the end of each of these swept-back arms that the front wheels  50  are located. 
     At the centre of the central section of the front cross-member  40  a steering column  70  projects upwardly. 
     At the top of the steering column  70  handlebars  80  are provided in the form of a “T” shape member. At each end of the handlebars  80  brake levers  140  are provided. These control brakes affect the rear wheels  120  by means of control wires  150 . 
     A seat pad  90  is provided behind the steering column  70 . The seat pad  90  has a dependent seat pad post  100  which fits into a corresponding socket  105  (refer to  FIG. 2 ) in the frame  20 . By this means the seat pad  90  may be raised and lowered to suit the individual user. Fixing of the seat post  100  relative to the socket  105  is effected by means of a knob, or resiliently biased pins, as will be readily understood. 
     A basket  130  is shown on the steering column  70 . 
     A handle  160  is provided underneath and rearwardly of the seat pad  90 . This handle aids collapsing or folding of the walker  10  as will be described below. 
       FIG. 2  shows the same walker  10  as  FIG. 1  but from a different angle. All of the features described and referenced in  FIG. 1  are the same. In addition,  FIG. 2  shows a knob  77  arranged towards the top of the steering column  70 . This adjustably clamps the handlebar post (which depends from the handlebars  80 ) within the steering column  70  and allows for the height of the handlebars  80  to be adjusted. 
     Further, a knob  76  is provided on the frame  20  between the two side members  30  and at the base of the steering column  70 . This knob is used to lock the steering column  70  relative to the frame  20  such that the steerable wheel  60  may be maintained in a forward facing position. 
     The knob  76  is attached to a pin which is extendable and retractable through a hole provided in the side of a socket  78 , located on the frame  20  and in which the steering column  70  sits, and a corresponding pin-receiving hole provided in the base of the steering column  70 . To lock the steering column  70  the pin is extended through the hole into the pin-receiving hole such that the steering column cannot rotate relative to the socket  78  provided on the front cross-member  40 . 
     The seat pad  90  has a groove  95  on its upper surface running from front to rear. This provides a more comfortable and secure place for the user&#39;s knee/leg to rest in use. 
     On the nearest shown side member  30  a pivot  35  is arranged approximately two thirds back from the front cross-member  40 . This pivot  35 , and a corresponding one located on the other distal side member  30 , allows the frame  20  to be folded as will be described in more detail below. 
     The socket  105  in which the seat pad post  100  is located is visible within the frame  20  approximately mid-way between the front cross-member  40  and the rear axle  110 . The socket  105  is attached to a plate  25  located between the two side members  30 . 
     The handle  160  is arranged transversely of the knee-walker  10  and located behind and underneath the seat pad  90 . This handle  160  enables the walker  10  to be collapsed/folded. To do this the handle  160  is grasped and lifted upwardly. This disengages a lock located between the rear edge of the plate  25  and the frame  20  such that the front and rear portions of each of the side members  30  may rotate relative to one another around the pivot  35 . Refer to  FIG. 5  for a view of the walker  10  in its folded position. 
       FIG. 3  shows the walker  10  from the side. The features referenced in this figure have already been described above with regard to  FIGS. 1 and 2 . The belt  200  is not shown in this figure for ease of understanding. One additional detail in  FIG. 3  is the swept-back nature of the front wheel  50  supports  55  depending downwardly from the front cross-member  40 . This swept-back arrangement aids the orientation of the front wheels  50  relative to the walker  10  as will be readily understood. Also a steering control mechanism  220  is generally indicated at the base of the steering column  70  as will be described in more detail below. 
       FIG. 4  shows the walker  10  from the front. The features referenced in this figure have already been described above with regard to  FIGS. 1 and 2 .  FIG. 4  is included to aid the understanding of the walker  10 . 
     The seat pad  90  is shown in the position to accept a right knee or leg. However, the seat pad post  100  can be completely removed from the socket  105 . The seat pad  90  can then be rotated 180 degrees about its vertical axis (i.e. about the length of the seat pad post  100 ) and then reinserted into the socket  105  such that the seat pad  90  is adapted for a left knee or leg. This is achieved because the seat pad post  100  is offset relative to the centre of the seat pad  90 . 
     The wheel pulley  210  above each front wheel  50  is shown, as is the steering control mechanism  220  directly underneath the steering column  70 . The steering belt  200  has been removed to improve clarity. 
     As discussed previously, the walker  10  may be folded-up. An example of this is shown in  FIG. 5  where it can be seen that the rear portion of the side members  30  have been swung about pivot  35  underneath the seat pad  90  and towards the front of the walker  10 . In this way, the rear wheels  120  are now located substantially underneath the seat pad  90 . 
     Also, the steering column  70  has been pivoted about the pivot referenced “ 75 ” such that it has been laid back over the top of the seat pad  90 . In this regard the seat pad  90  has been lowered to its full extent and the handlebars  80  have been retracted into the steering column  70  to their fullest extent. The basket has also been removed. In this way, the volume required to fit the walker  10  may be reduced. This is useful for storage and transportation. The overall length of the walker  10  in the folded position is approximately 533 mm, and the overall height is approximately 431 mm. 
     To unfold the walker  10 , the rear portions of the said members are pulled around pivot  35  to their previous position and the handle  160  is then pushed down to lock them in place. 
     In another embodiment (not shown), instead of the handle  160  being provided under the seat pad  90 , a pull-knob is provided on one of the pivots  35 . The pull-knob (or handle) is connected to a pin. With the walker  10  in the unfolded state the pin extends through two aligned holes, each one provided on each part of the pivot (i.e. a part of the pivot on each section of the side member). With the pin in place in the two aligned holes the walker cannot be folded. However, when the pin is removed the two parts of the pivot may rotate relative to one another. The pin may be spring-biased and always connected to an outer part of the pivot, or could be provided on a chain and be completely removable from the pivot. 
     A partial underside view of the front of the walker  10  is shown in  FIG. 6 . Each of the two front wheels  50  are shown a respective end of the front cross-member  40 ; the front cross-member  40  being supported at the end of the side members  30 . In the centre of the front cross-member  40  the steering control mechanism  220  is visible. This comprises of a steering column attachment  230  which allows the steering column to be retained and yet rotate relative to the front cross-member  40 . A first plate  225  is attached to the underside of the cross-member  40 . A second plate  250  is attached to this first plate  225  by means of bolts  270 ,  280 . This plate has slots  260  through which these bolts  270 ,  280  pass. The slots  260  allow the two plates  225 ,  250  to be adjustably fixed relative to one another in various sliding relationship. At one end of the second plate  250  two tensioner pulleys  240  are attached. 
     The steering column includes a pulley  218  (refer to  FIG. 5 ) at its basal end. The steering belt  200  passes in a loop around this steering column pulley  218 , around each tensioner pulley  240  and around each wheel pulley  210 . The adjustable fixing nature of the tensioner pulleys  240  allow for the steering belt to be tensioned to ensure effective steering. Steering is enabled by rotation of the steering column  70 , causing rotation of the steering column pulley  218 , causing rotation of the steering belt  200 , causing rotation of the wheel pulleys  210 , and causing rotation of the front wheels  50  in unison. The belt  200  is shown as toothed. The belt  200  may, in one embodiment (not shown) be smooth and not toothed. The various pulleys  210 ,  218 ,  240  may be toothed to cooperate with the teeth on the belt  200 , or may be smooth. A combination of toothed and non-toothed pulleys  210 ,  218 ,  240  may be provided. 
     The walker  10  may have a relatively tight turning circle as a result of the arrangement of the front wheels. The radius of the turning circle may be equivalent to the length of the walker  10  if only the rear wheels  120  (and not any of the front wheels) are able to be dragged around. 
     The walker  10  may have an overall length of approximately 762 mm, and a maximum width of approximately 406 mm. 
     The front wheel base may have a width of approximately 394 mm, and a rear wheel base width of approximately 215 mm.