EP2289478A1

EP2289478A1 - A-frame walker

Info

Publication number: EP2289478A1
Application number: EP09168949A
Authority: EP
Inventors: Karl Tate
Original assignee: Individual
Current assignee: TATE, SHAHE
Priority date: 2009-08-28
Filing date: 2009-08-28
Publication date: 2011-03-02

Abstract

According to the invention a walking aid comprising in combination a front member and a rear member, each having a pair of mono-directional ratchet type wheels at its lower ends, hinge means with adjustable degree of rotational freedom pivotally connecting the said front and rear members together at their upper ends, adjustable spring means around the pivots connecting the said hinges providing resistance when front member extends forward and assistance when rear member retracts forward, a rearward extending u-shaped handlebar with handgrips attached to the rear member for support, between which user stands squarely within the wheel base. Pushing down on the said handgrips forces the rear ratchet wheels to anchor on the supporting surface allowing the front wheels to advance spreading the supporting trestle-like structure, pulling up on the handgrips forces the front ratchet wheels to anchor and allow the rear wheels to retract to original position.

Description

The present invention relates to wheeled walking aids, in particular to mechanically engineered appliances for assisting persons with impaired function of lower extremities who are unable to walk with the use of prior art walking aids because they lose their delicate balance when obliged to lift and/or push the frame partially or totally off the supporting surface. It is the main aim of the present invention to provide a low cost walking aid that offers a better technique for advancement and obviates the requirement to lift and/or push the frame.
The present invention unlike the prior art walking aids is engineered to advance in sync with user, step-by-step without the user ever having to lift the frame totally or partially off the supporting surface to advance, the frame is mechanically engineered to progress on all four mono-directional ratchet wheels, by simulating a gait cycle known as the "two-anchor movement" which works on the same principle that the inchworm uses, whereby on either end of the body/frame, the clasping appendages/ratchet wheels, allow it to move by anchoring first the rear end and then moving forward the front end, then anchoring the front end and moving forward the rear end in predetermined lengths.
Many forms of support for walking have been provided, of greater or lesser complexity, to accommodate differing degrees of severity of injury/illness. Typically, standard walking aids are supported on four fixed standing legs, pulpit-like frames constructed of aluminum tubing, permitting relatively dysfunctional users, while holding the upper portion of the frame, to stand, steady themselves and attempt to advance. To achieve a fluent walking pattern with one of these prior art frames is not an easy task because body alignment, trunk positioning, weight distribution, balance, stability and control are all compromised when walking needs to be effected by the user, intermittently lifting the frame off the ground, repositioning it ahead, then stepping forward. In the anxious days following an accident or stroke, many patients have difficulty in lifting and sliding a frame forward due to a multitude of factors, compounded by a state of fear, shock and lack of focus, coordination, balance and confidence.
There have been attempts to introduce other forms of walking aid to overcome the need for having to lift the frame totally off the supporting surface, the most relevant being United States Patent No. 2,656,874 from W.C. Robb, 1953 , but this and other similar inventions have not been successful due to the instability of their method of advancement.
A serious additional problem with most prior art walking aids is that they promote stooping, which can exacerbate the user's condition. To this end, two-wheeled pulpit frames have been provided by prior art with wheels on the front legs, replacing the ferrules, but these are not a great improvement on the standard fixed pulpit frames.
It is hoped that by using simple step rehabilitation devices like the present invention some of these problems can be circumvented. Designing better and cheaper equipment for the home that can, for example, reduces the number of therapists needed for supervision. In the continuum of care, efforts in the direction of increasing medical equipment and services for the home can be the most cost-effective.
According to the invention a walking aid comprising in combination a front member and a rear member, each having a pair of mono-directional ratchet type wheels at its lower ends, hinge means with adjustable degree of rotational freedom pivotally connecting the said front and rear members together at their upper ends, adjustable spring means around the pivots connecting the said hinges providing resistance when front member extends forward and assistance when rear member retracts forward, a rearward extending u-shaped handlebar with handgrips attached to the rear member for support, between which user stands squarely within the wheel base. Pushing down on the said handgrips forces the rear ratchet wheels to anchor on the supporting surface allowing the front wheels to advance spreading the supporting trestle-like structure, pulling up on the handgrips forces the front ratchet wheels to anchor and allow the rear wheels to retract to original position.
It is also the aim of this invention to provide a walking aid designed to place the user's centre of mass at the optimal functional position, squarely within the wheel base to help encourage an upright body posture, a 'neutral spine' trunk stability and support throughout the process to give greater confidence to patients who can't stoop over without loosing their balance.
It is also the aim of this invention to provide a walking aid that can be converted to accommodate patients with varying degrees of instability and differing surfaces. For example the standard mono directional, ratchet type rear wheels as shown in fig. 6 that incorporate a safety brake mechanism to engage when the slightest additional or sudden unintended pressure or load is applied in the forward direction. Another option is the mono-directional ratchet type wheel with a pin mechanism that when disengaged allows the user forward and reverse mobility. Another option is a mono-directional front swivel type wheel with locking mechanism that can switch from swivel to non-swivel still retaining the anti roll-back feature.
It is also the aim of this invention to provide a walking aid that can be used as painlessly as possible by offering anatomically contoured hand grips, a natural wrist angle to spread weight over a wider area of the palm helping reduce the pressure on the carpal tunnel and improve blood circulation especially when transferring some or all of the weight through the forearms to the frame previously carried through the legs, giving the lower limb joints the necessary support thus minimizing pressure over weight bearing joints as well as impact on the lower spine, hip, knee, ankle and foot.
It is also the aim of this invention to supply a walking aid with adjustable forearm cuffs like elbow crutches that can be extended between the handgrip and cuff of forearm, further ensuring correct positioning of the body within the frame as well as enhancing stability, control, balance and comfort.
It is also the aim of this invention to provide a walking aid that is easily adjustable in width and height to fit any size to help the unique user achieve the perfect supporting stance within the frame with elbows naturally bent, at an angle of approximately 15 degrees flexion and wrist bones in line with the handgrips.
It is also the aim of this invention to provide a walking aid with an adjustable spring or hydraulic damping means to urge the front and rear members to alternately spread and retract relative to each other to the desired requirement of the user.
In order that the invention may be more clearly understood, one form of walking aid made in accordance with the invention is described with reference to the accompanied drawing wherein. Although the present preferred form of this invention has been herein shown and described, it is to be understood that such has been done for purposes of illustration only, and that various changes may be made therein within the scope of the appended claims.

Figure 1, shows a side view of the apparatus locked in the minimum aperture as well as shadows of the same apparatus locked in the maximum and minimum apertures.
Figure 2, shows an end view the apparatus from the rear.
Figure 3, shows a top view cross section of the connecting link, torsion spring.
Figure 4, shows a side view of the connecting link, torsion spring, damper and hinge mechanism in the minimum aperture position.
Figure 5, shows a side view of the connecting link, torsion spring, damper and hinge mechanism in the maximum aperture position.
Figure 6, shows details of an alternative attachment with Sure Grip safety breaking mechanism.

The walking aid comprises a back member 2a with a mounted u-shaped bar 2c, forming the back end which is pivotally linked with a torsion spring system at 3 near the top ends of each of the back legs 2a&2b attaching to the front legs 1a&1b which are interconnected by cross bars 1c&1d to form a front member that is pivotally attached to the back member as in a trestle-like structure. At the feet of both the front and back legs 1a, 1b&2a,2b are mounted mono-directional ratchet type wheels 4 to prevent backward slip at all times when in use.
The front and rear legs of the said trestle like structure are joined near the top 3 by a pivotally attached torsion sprung link and damper system as shown in figures 3 ,4&5. On either side, comprising rear links 2e, 2d and front links 1e, 1f pivotally attached to the rear and front legs respectively and pivotally attached to each other by a pivot 7. The back link is formed with slots relative to the pivots 2d (ii) in which move pin members 9 attached to the front links 1e, 1f. Between the over-lapping ends of the links are positioned springs 6 which tend to draw the legs towards one another.
As seen from Figure 1 and Figure 2 each pair of front and rear links forms a stay which not only limits the opening or separation of the front and rear members but also limits their closed position so that in either position they provide a stable trestle-like structure from which the user can obtain support in all directions.
On the top of the back member 2a, 2b is mounted an inverted U-shaped top bar 2c for the handles. The handles are completed by rubber grips 5 that project rearward to permit the user to stand between the handles and obtain support there from.
As seen from Fig. 3, 4 and 5 the spring 6 shown in Figure 3 is coiled around the pivot 7&8 and has its ends bent outwardly and located in holes in the links 2d(i) and 1f(i) respectively.

Claims

What I claim as my invention is a walking aid comprising in combination a front member and a rear member each having a pair of mono-directional ratchet type wheels at its lower ends, hinge means with adjustable degree of rotational freedom pivotally connecting said front and rear members at their upper ends, adjustable spring means around the pivots connecting the said hinges providing a stable trestle-like structure with adjustable degree of rotational freedom. A rearward extending u-shaped handlebar with handgrips is attached to the rear member, allowing the user to stand squarely within the wheel base and advance by alternately pushing down and pulling up on the handgrips, which correspondingly anchor the rear and front ratchet wheels, allowing the trestle-like structure to move forward by spreading and retracting to its original position.