TITLE "A WHEELED CONTRIVANCE AND A STEERING MECHANISM FOR THE WHEELED CONTRIVANCE"
FIELD OF THE INVENTION This invention relates to a steering mechanism for a wheeled contrivance. It also relates to a wheeled contrivance including the steering mechanism. This invention relates particularly but not exclusively to a walker or walking aid and a steering mechanism therefor and it will be convenient to hereinafter describe this invention with reference to this example application. However it is to be clearly understood that the invention is capable of broader application. For example the invention could be applied to wheeled contrivances other than walkers such as people movers, trolleys, wheelchairs, carts, barrows, and other vehicles.
BACKGROUND TO THE INVENTION A contrivance known as a walker or walking aid is used to assist old and frail people to move from one place to another. The walker comprises a frame with a lower end that can be mounted in a stable fashion on a horizontal support surface, and an upper end that serves as a hand rail. Typically the frame is an open frame that is made of hollow tubing such as aluminium tubing so as to make it suitably light and portable. The user supports themselves against the walker or walking aid and moves or shuffles forward and then periodically moves the walking aid forward in stepwise increments. In addition to providing vertical support, the walker or walking aid also offers lateral stability. It sits easily on the ground and does not require any support for it to stand on the ground. It therefore offers considerably more lateral support than a walking stick which cannot stand upright on its own. In addition a wheeled walker or walking aid is also known. This comprises a framed structure somewhat like that for the walker described
above, that is mounted on wheels. In addition to offering support to a user the frame can also be wheeled across a support surface. It therefore does not have to be lifted up and carried forward periodically like the walker described above. It is simply wheeled across the support surface as the user advances either in shuffles or small walking steps. Yet further an apparatus called a patient lifter is also known. This is similar to the walker or wheeled walker described above with the additional feature of an extensible vertical member extending up from the base to the hand rail and a drive means for driving this vertical member and the associated hand rail up and down. Typically this apparatus also includes a body support that is mounted on the handle formation and moves up and down with the handle formation. The body support may be in the form of a belt, sash or harness or other bottom support. This is passed around and over the buttocks and/or thighs and/or back of the body of the user. By raising the vertical member and handle formation, the body of the user can be lifted from a seated or lying position to a fully extended upright position. The apparatus is typically used to lift incapacitated patients such as stroke victims and the like and then move them around as required. A limitation of the wheeled walkers described above is that they do not have steering mechanisms. Typically the wheels are castors that do not have any directional bias. In addition they don't have any brakes. Consequently it can be difficult for a user, particularly an old and frail user, to slow the wheeled walker down and then turn it around and push it off in a new direction.
OBECT OF THE INVENTION It is an object of the invention to provide a method and apparatus for steering and braking wheeled walkers. It is another object of the invention to provide a useful alternative to existing walkers Further objects will be evident from the following description.
SUMMARY OF THE INVENTION According to one aspect of this invention there is provided a wheeled contrivance comprising: a chassis; at least two laterally spaced adjustable wheel assemblies mounted on the chassis; a transverse steering rod mounted on the chassis; and one pivot transmission means extending from the transverse steering rod to one wheel assembly, and another pivot transmission means extending from the transverse steering rod to the other wheel assembly, whereby pivoting of the transverse steering rod in one direction effects a displacement of both said pivot transmission means which turns both wheels outward at their leading ends so that they adopt an open position, and pivoting the transverse steering rod in the other direction effects an opposite displacement of both said pivot transmission means turning both wheels inwardly at their leading ends so that they adopt a closed position. The wheeled contrivance preferably further comprises a control member for enabling a user to pivot said transverse rod in either said one or other direction and thereby effect movement of the laterally spaced wheels into and out of the open position and into and out of the closed position. In the open position with the leading ends of the wheels pointing outwardly the wheeled contrivance can be turned left or right freely by a user. When the turn is completed the transverse steering rod can be returned to its starting or neutral position and then the wheels will be aligned with each other and point in a forward direction for forward movement. By contrast in the closed position the wheels extend transverse to the forward direction with the leading ends of the wheels facing inwardly and are not in a suitable position to effect a turning movement of the contrivance.
Consequently the wheels in this closed position exert a braking influence on the vehicle. Thus the contrivance has a steering mechanism that aligns the wheels properly for straight ahead travel and then can be activated to facilitate left
and right turning movements with the wheels. It can also be activated differently to brake the contrivance and perform the function of a braking system. In summary the steering system holds the wheels in position both for straight ahead movement and turning and in addition the steering system has a braking capability. In one form pivoting the steering rod rearward ly moves the wheels to the closed position and pivoting the steering rod forwardly moves the wheels to the open position. Each pivot transmission means may comprise a linkage fast with the steering arm and a push rod operatively connected to the linkage so as to convert a pivoting movement of the steering arm to a push/pull of the push rod. Each push rod will be operatively connected to the associated wheel assembly. Conveniently each wheel assembly may have a push rod mounting projecting away from an inner surface of the wheel bracket to which the push rod is operatively connected, eg pivotally. The two push rods may be of equal length. Further each of the push rods may extend rear ardly at the same angle relative to the steering rod. Accordingly turning of the steering rod may produce the same amount of turning of the wheel assemblies. The push rod mounting may project outwardly and rearwardly away from the wheel bracket whereby the connection of the push rod to the push rod mounting is positioned rearwardly of the centre of the wheel. Thus when the push rod is pushed rearwardly it turns the associated wheel to the closed position and when it is pulled forwardly it turns the associated wheel to the open splayed position. The control member may be a foot pedal connected to the steering rod, eg directly, such that pivoting of the pedal, eg forwardly or rearwardly, will have a corresponding effect on the transverse steering rod. More specifically the pedal may comprise an upright member extending up from the steering rod, and front and rear pedal elements spaced respectively forwardly and rearwardly of the upright member, and a
connecting member connecting the front and rear pedal elements to the upright member. The upright member may be one of said linkages. The wheeled contrivance may further include a ground engaging formation longitudinally offset from said two laterally spaced wheels, eg forwardly or rearwardly of said laterally spaced wheels. The purpose of this ground engaging formation is to stabilise the vehicle in position on a support surface so that it does not tip forwardly or rearwardly. This enables it to sit on a support surface in a stable fashion. The ground engaging formation may be in the form of a wheel, eg a jockey wheel, spaced forwardly of the two laterally spaced wheels. Conveniently the jockey wheel may also be spaced approximately midway between the two laterally spaced wheels. In one form the jockey wheel is a castor capable of pivoting freely in all directions about a vertical axle. The base may be in the form of a chassis and the chassis in turn may be in the form of an open frame, eg a substantially rectangular open frame made of a hollow tube material.
Typically this material may be a light metal such as aluminium. The base may comprise a chassis to which the wheels are mounted, eg an open frame chassis. The open frame chassis may have a platform or floor support mounted thereon. Alternatively the open frame chassis may be open and the user stands within the frame with their feet on the support surface or ground across which the contrivance is wheeled. The wheeled contrivance may further include an upright support extending up from the base. Preferably the upright support includes a handle formation positioned at about waist height or the typical height of the hands of a user when their arms are partially extended. The upright support may comprise a central post extending up from a central front region of the base and the handle formation may comprise transverse handle bars mounted at the top of the central post and extending perpendicularly outwardly therefrom. Further the terminal ends of the transverse handle bars may turn rearwardly much like the handle bars of a bicycle. Yet further the handle formation may include auxiliary handle bars
extending forwardly and downwardly of the transverse handle bars. The wheeled contrivance may also include means for resisting rearward tipping of the vehicle. This means for resisting rearward tipping may include a pair of laterally spaced ground engaging formations spaced rearwardly of the left and right wheels. The ground engaging formations may be positioned so as to sit spaced above a support surface when the wheeled contrivance adopts its normal operating position. Thus the ground engaging formations only come into contact with the ground when the contrivance is tipped rearwardly. The ground engaging formations resist any further rearward tipping when they come into contact with the ground. Conveniently the ground engaging formations may comprise a pair of laterally spaced wheels that are in the form of castors. The wheeled contrivance may further include a body support formation for supporting the body of a user. This may be in the form of a seat, belt, sling or harness extending under and around the thigh region, buttocks or back of a user. This body support formation thus helps support the user in an upstanding position. It also resists them from falling backwards. The wheeled contrivance may further include a The wheels contrivance may be a walker or walking frame. The wheeled contrivance may also be a people mover.
BRIEF DESCRIPTION OF THE DRAWINGS A wheeled contrivance and steering mechanism in accordance with this invention may manifest itself in a variety of forms. It will be convenient to hereinafter describe in detail preferred embodiments of the invention with reference to the accompanying drawings. The purpose of providing this detailed description is to instruct persons having an interest in the subject matter of the invention how to carry the invention into practical effect. It is to be clearly understood however that the specific nature of this detailed description does not supersede the generality of the preceding broad description. In the drawings:
FIG. 1 is a schematic three dimensional view of a prior art walking frame; FIG.2 is a three dimensional view of a first embodiment of a walker in accordance with the invention; FIG.3 is an enlarged three dimensional view showing the chassis and wheels of the walker of FIG. 2 in a neutral straight ahead position; FIG. 4 is a top plan view of the chassis and wheels of FIG. 3; FIG. 5 is a side view of the chassis and wheels of FIG. 3; FIG.6 is an enlarged three dimensional view showing the chassis and wheels of the walker of FIG. 2 in a closed position with the leading ends of the wheels pointing inwardly; FIG. 7 is a top plan view of the chassis and wheels of FIG. 6; FIG. 8 is a side view of the chassis and wheels of FIG. 6; FIG. 9 is an enlarged three dimensional view of the chassis and wheels of the walker of FIG. 2 in an open splayed position with the leading ends of the wheels pointing outwardly; FIG. 10 is a top plan view of the chassis and wheels of FIG. 9; FIG. 11 is a side view of the chassis and wheels of FIG. 9; FIG. 12 is an enlarged view of the control member and transmission means; FIG. 13 is a three dimensional view of a second embodiment of a walker in accordance with the invention; FIG. 14 is a three dimensional view of a third embodiment of a walker incorporating a lift-assist mechanism; FIG. 15 is a three dimensional view of a fourth embodiment of a walker incorporating a removable handle arrangement; and FIG.16 is a three dimensional view of a fifth embodiment of a walker incorporating an alternative lift-assist mechanism.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A walker of the general type known in the prior art is illustrated for background information in FIG 1. The prior art walkers are generally simple
frames that provide support to a person who has difficulty walking. A first embodiment of an improved walker or walking aid in the form of a wheeled contrivance, generally indicated as 1 , is depicted in FIG 2. The walker 1 comprises broadly a chassis 2 on which a pair of laterally spaced wheel assemblies 3 and 4 are mounted. An upright support 5 extends up from the chassis 2. The upright support 5 has a handle formation 6 mounted thereon at about waist height. The chassis 2 also has a jockey wheel assembly 8 in the form of a castor positioned forward of the wheel assemblies 3 and 4. The wheel assembly 8 is positioned broadly midway between the wheel assemblies 3 and 4. The jockey wheel assembly 8 includes a castor brake 9. The walker 1 also has means for resisting rearward tipping of the walker in the form of a pair of raised wheels 10, 11 that are raised above the ground when the walker stands on a support surface. The walker 1 also has steering means in the form of a steering mechanism 15 for steering the laterally spaced wheels 3 and 4 and also exerting a braking action to these wheels 3, 4. We now discuss each of these components of the walker in more detail. The chassis 2 comprises a broadly rectangular open frame of hollow tubular metal. Preferably the metal chosen is a light metal such as aluminium. Optionally the walker may have a standing platform extending across the open frame of the chassis. A standing platform is shown in the embodiment of FIG 13 discussed later. Each of the left and right wheel assemblies 3, 4 respectively comprises a mounting bracket 20 rigidly mounted on the chassis 2 with a wheel bracket 21 and wheel 22 collectively mounted to the mounting bracket
20. The wheel bracket 21 and wheel 22 as a whole are capable of pivoting about a vertical axis relative to the mounting bracket 20. Each wheel bracket 21 passes over the top of the associated wheel and down each side thereof and has an axle 24 passing through the centre of the wheel 22. The wheel 22 can rotate freely relative to the bracket 21
and the axle 24. The third wheel assembly 8 similarly comprises a mounting bracket 26 and wheel bracket 27 on which a wheel 28 is mounted. The mounting bracket 26 is mounted on the upright support 5 a small distance above the chassis 2 and extends forwardly therefrom. The wheel bracket 27 and wheel 28 are pivotable relative to the mounting bracket 26 about a vertical axis and the wheel 28 is mounted on an axle 29 which in turn is mounted on the wheel bracket 27. The wheel 28 and the wheel bracket 27 as a whole are free to pivot or rotate relative to the mounting bracket 26 about a vertical axis much like a castor. The elevated rear wheels 10, 11 for resisting rearward tipping are mounted on brackets 31 , 32 extending rearwardly from the chassis 2. The brackets 31 , 32 turn upwardly as they extend away from the chassis so that the wheels 10, 11 are elevated a distance off the ground in normal use. The wheels 10, 11 are freely rotatable relative to the mounting bracket 31 about a vertical axis much like castors. The two wheels 10, 11 are laterally spaced a small distance apart from each other and are received well within the lateral extent of the left and right wheel assemblies 3 and 4. The upright support 5 comprises a centrally positioned post that extends upwardly from the chassis 2 to about the waist height of the average user. The handle formation 6 extends both left and right from the top of the post 5 to provide left and right handle bars to be held by a user. In the illustrated embodiment after the handle extends outwardly to form the left and right handle bars, it curves rearwardly and then downwardly to the wheel brackets 20 of the left and right wheels 3 and 4. In addition the handle formation 6 further includes two laterally spaced auxiliary handles 34, 35 projecting forwardly and downwardly from the handle bars on either side of the central post 5. These auxiliary handles may be used by a carer to assist the user. In addition the illustrated embodiment includes a bottom support or seat 40. This comprises left and right members 41 and 42 extending upwardly from the chassis 2 from points proximate the left and right wheels 3
and 4. It also includes a broadly planar seat element 44 mounted at the top of the members 41 and 42. The purpose of the support 40 is to carry the weight of a user. If a standing platform is also included, as in FIG 13, the user may be seated on the support 40 and moved by a carer using the handles 34, 35. The steering mechanism 15 is seen most clearly in FIG 3 and FIG 4. It comprises broadly a steering rod 45 pivotally mounted on the chassis and extending transverse relative to the chassis 2. The mechanism 15 also includes left and right pivot transmission means, each in the form of linkages 46 and push rods 47 extending between the steering rod 45 and respectively the left and right wheel assemblies 3, 4. Each linkage 46 is fast with the steering rod 45 and extends upwardly to a pivoting attachment 43 to the associated push rod 47. That way pivoting of the steering rod 45 is translated into push and/or pull of the push rod 47 which in turn leads to pushing or pulling of the associated wheel assembly 3 or 4 and consequent turning of the wheel. As is shown clearly in FIG 4 each push rod 47 is pivotally attached to a push rod mounting formation 48 projecting outwardly and rearwardly away from the inner surface 49 of the wheel bracket 21. The steering mechanism 15 also includes a control member in the form of a control pedal 50 extending upward from one side of the steering rod 45. The control pedal 50 is an upright member (which in the illustrated embodiment is the left linkage) fast with the steering rod 45 and extending upwardly therefrom, and longitudinally spaced heel and toe pedal elements 52 and 53 for receiving and supporting the heel and toe of the user. Thus by adjustment of the foot inclination on the pedal elements 52 and 53 a user can effect a forward or rearward pivoting of the steering rod and consequent turning of the left and right wheel assemblies 3 and 4. As seen more clearly in FIG 5, the control member includes a plate 54 with preset positions 55 that position the control pedal 50 in a neutral, pivot or lock position. This is described in more detail later with reference to FIG 12. In use the walker 1 is used to assist a person in walking from one
point to another point. The user is positioned standing inside the open frame 2 facing forward towards the wheel assembly 8. The user has their hands on the handle formation 6. They walk along the floor in a forward direction pushing the walker as they go. The wheel assemblies 3 and 4 are not castors and they are aligned in the direction of travel by the steering mechanism 15. The walker assists the user by enabling the user to rest their weight on the walker 1 , eg by leaning on the handle formation 6 and/or supporting their middle body on the bottom support 40. If the user desires to stop the forward movement of the walker 1 , they can effect a braking of the walker 1. To do this they pivot the foot pedal 50 backward to displace the steering rod 45 and thereby push rods 47 rearward, as shown in FIGS 6-8. This pushes the push rod mounting on the wheel brackets and the rear of the wheels 22 outwardly and pushes the leading end of the wheels 22 inwardly. This is known as the closed position. The closed position has the effect of braking the walker 1. As the wheels 22 are transverse to the direction of travel the walker 1 can only be advanced by sliding the stationary wheels 22 transversely over the support surface as distinct from rolling the wheels 22 over the surface. Once again the wheels 22 can be restored to the neutral straight ahead position by pivoting the brake pedal 50 back to its previous or neutral position. When the user decides to make a turn, say at ninety degrees, the user lifts their left foot onto the foot pedal 50 and pivots it forward. This has the effect of pivoting the steering rod 45 to displace the push rods 47 forwardly, as shown in FIGS 9-11. This has the effect of displacing the push rod mounting on the wheel bracket and the rear end of the wheels 22 forwardly and inwardly. This in turn causes the front of the wheels to turn outwardly. In this open position, the wheels 22 are suitably aligned for making left and right turns with a smooth rolling wheel action. Each of the wheels 22 is aligned on the circumference of a circle having a centre intermediate and forward of the two wheels 22. Once the turn has been carried out the user
can return the pedal 50 to the previously neutral position. This effects a rearward pivoting of the steering rod 45 and a rearward displacement of the push rods 47. This straightens out the wheels again to a position suitable for forward displacement. As seen most clearly in FIG 12, the control pedal 50 is positively held in each active position, being the neutral position, the closed or locked position and the open or steering position. A plate 54 is attached to the chassis 2 and has three holes, such as 55, corresponding to the three positions. A corresponding bump or protrusion on the linkage 46 seats in a hole 55 to hold the control pedal in the desired position. A second embodiment of a walker 1 is shown in FIG 13. The walker of the second embodiment is virtually identical to the first embodiment but with the addition of a standing platform 60 and padding 70. The padding 70 may include substantially horizontal knee padding 71 with a substantially vertical central pad 72 disposed between padding 71 to keep the knees apart. Padding 71 , 72 is mounted to a substantially T-shaped bar 74, which is in turn mounted to upright support 5 by a locking mechanism 75. The T-shaped bar 74 is height adjustable. Central pad 72 prevents excessive hip abduction and internal rotation to prevent the knees rolling in. Furthermore, padding 71 are angled inwardly toward central pad 72 to discourage hip abduction and thus to discourage the knees rolling out. These features encourage the lower limbs to be maintained in a position of symmetry and discourage lower limb patterns that can cause problems and instability. Padding 71 , 72 helps to keep the user relatively still in the walker 1 and reduces the possibilities for injury. Shin, ankle and leg padding 73 are provided at a lower level of the walker 1. This prevents the user's feet from slipping forwards and consequently injuring themselves. This embodiment is particularly useful for users that have limited mobility and, perhaps, a motor disorder. It will normally be the case that users will be seated in the walker 1 on seat 40 and moved around by a carer using the auxiliary handles 34, 35. A third embodiment of a walker 1 is shown in FIG 14. The third embodiment is very similar to the second embodiment of FIG 13 but with the
addition of a lift assist device 80 in place of the seat 40. The lift assist device 80 is used to assist a user into the walker, A user may be seated in a chair or on a bed and be unable to muster the strength to move themselves to the walker. However, once in the walker they may have sufficient strength to support themselves and move around. To assist the user to move into the walker the lift assist device 80 has a sling 81 that is positioned about the buttocks of the user. Upper frame elements 82 are extended by mechanical, hydraulic, pneumatic or electric extension device 83 relative to lower frame elements 84. The result is that as the frame 82, 84 extends the user is lifted to their feet. Alternately the user may only be lifted sufficiently to reposition a seat 40 in the manner shown in FIG 13. A fourth embodiment of a walker 1 is shown in FIG 15. The fourth embodiment is very similar to the third embodiment of FIG 14 but with the addition of a removable handle arrangement 90. Handle arrangement 90 comprises upright portions 92, integrally formed inclined portions 94 and integrally formed end portions 96 comprising handles 98. Handle arrangement 90 extends upwardly and downwardly from handle formation 6 and may be mounted via upright portions 92 to handle formation 6 or to auxiliary handles 34, 35 as shown in FIG 15. Handle arrangement 90 is prevented from forwards or backwards motion relative to the walker 1 by locking members 100 bearing against upright support 5. The handle arrangement is used for exercise and rehabilitation purposes and is easily attached to and detached from the walker 1. A user standing in the walker 1 grabs each of the handles 98 of the handle arrangement 90 and pulls themselves up straight, thus helping with their postural extension. A fifth embodiment of a walker 1 is shown in FIG 16. The fifth embodiment has the same chassis and wheel arrangement of previous embodiments and the lower level shin, ankle and leg padding 73 shown in the embodiments of FIGS 13 and 14. This embodiment also comprises the upright support 5 and handle formation 6 of previous embodiments, but they have been excluded from FIG 16 for the sake of clarity. This embodiment
comprises an alternative lift-assist mechanism 110 to assist lifting the user into an upright position. Mechanism 110 is mounted to the chassis 2 forward of rear wheels 10, 11 via members 112. Laterally spaced apart handles 114 are pivotally mounted to respective members 112 and handles 114 are joined together by cross member 116. Laterally spaced apart support members 118 support padding 120 and are pivotally mounted to respective handles 114. Padding 120 provides support for a user's lower back region. Laterally spaced apart linkages 124 are pivotally mounted to respective members 112 and respective support members 118. Padding 122 is supported between linkages 124 and provides support to the rear of a user's upper thigh region. With a user's feet placed on standing platform 60 and secured in position by padding 73, movement of the handles 114 in a forward direction generated either by a user or a carer will assist in lifting the user to an upright position by virtue of padding 120 and 122 supporting the user's lower back and upper thighs respectively. An advantage of the walker or walking aid described above is that it can easily be steered by a user by a simple adjustment in the attitude of a brake pedal. By a forward pivoting of the brake pedal the leading edge of the edges of the left and right wheels turn out. They are then aligned with a perimeter of a circle having its centre in between and forward of the wheels and the walker can be turned freely and easily in both left and right directions. This enables a frail and weak user to easily and safely change the direction of travel of the walker in accordance with their need. Afterthey have completed the turn the simple rearward pivoting of the brake pedal returns the wheels to the neutral straight ahead position for straight and forward travel. A further advantage of this contrivance is that by a simple rearward pivot of the brake pedal the left and right wheels can be moved to the closed position which tends to brake the walker. Thus the steering mechanism also provides a simple braking mechanism as well as the steering function described above. This again is most useful for frail and infirm people as it enables them to safely and effectively brake the walker to a halt when they
desire to stop moving forward. They do not need to use their bodies and muscles to effect this braking of the walker. The inertia in a forward moving walker would be comparable to that in a shopping trolley. It requires a fair amount of effort to turn a laden shopping trolley that is moving forward through ninety degrees. A yet further advantage of the steering mechanism of the walker is that it is relatively simple and can be incorporated into a walking frame or walker at a modest additional cost. Yet further it will not require substantial redesign of existing walkers. Yet further its relative simplicity should mean that it is easy to machine and fit. Even yet further its relative simplicity should mean that it is reliable in operation. It will of course be realised that the above has been given only byway of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.