WO2001058404A1

WO2001058404A1 - A method and apparatus for lifting, transporting and/or supporting persons

Info

Publication number: WO2001058404A1
Application number: PCT/DK2001/000080
Authority: WO
Inventors: Gert Steen RØNNE
Original assignee: Borringia Industrie AG
Current assignee: Borringia Industrie AG
Priority date: 2000-02-07
Filing date: 2001-02-05
Publication date: 2001-08-16
Anticipated expiration: 2002-08-07
Also published as: AU3003001A

Abstract

A disabled person may be lifted or supported by means of an apparatus comprising a supporting frame member, which may be in the form of a column (10) and a lever (11), which is pivotally mounted on the supporting frame member or column (10) at a pivot point (12). Connecting means, such as a sling or a saddle, allows the person to be suspended from or to sit on the lever (11) adjacent to its free end (21). In order to lift or support the person the lever (11) biasing means (13), such as a spring device, is biasing the lever in an upward direction. The lifting or supporting intensity of the biasing means may be regulated or varied by means (17, 19) for changing the moment of force or torque applied to the lever (11) by the biasing means, so as to allow adjustment of the lifting or supporting force (W) applied to the person to be lifted or supported.

Description

A method and apparatus for lifting, transporting and/or supporting persons

The invention relates to a method and apparatus for lifting, transporting and/or supporting persons, especially disabled persons.

Fully or partially paralysed persons nearly always need assistance when they wish to move from one piece of furniture to another or when moving between mobility aid products, e.g. from bed to wheelchair.

Traditionally, such assistance has been provided by helpers, nurses, spouses, or other persons. Due to the heavy strain, which such assistance imposes on the body of the helper, a number of hoisting devices have been invented over the years.

The first person hoists were typically manually operated devices, where the force needed to lift the patient was supplied by the helper, often through some kind of hydraulic device. The hoists could be either stationary or mobile, i.e. mounted on wheels or suspended from the ceiling of a room.

Various types of patient support systems have been used over the years, such as slings in which the patient is fully suspended, sling systems which require the patient to support part of his body weight on his own feet, and rigid support devices of various shapes, those most commonly used being shaped like saddles, chairs or stretchers.

Today nearly all person hoists have motorised systems, in which a motor supply the force needed to lift the person or patient. As an example, a lifting device may comprise a threaded spindle, which may be rotated by an electric motor and which may co-operate with a nut member moving up or down on the spindle when rotated by the motor. The patient support system is, either directly or via an arm mounted on the nut member.

Another commonly used device for lifting a patient support system comprises a reel having a belt or strap fixed thereon and being driven by an electric motor. When the motor is energised the belt is winded onto the reel thereby lifting the patient support system and the patient. When the belt is unwound, the patient support system and the patient are lowered. Other patient lifting devices differing slightly from those described above are known. However, they are all of a structure so as to share the following trait, which is not in agreement with ideal lifting or supporting of mobility impaired persons, whether they are manipulated in this condition by a carer or moving through their own action:

In order for any lifting or supporting to take place using known constructions, the following inequality must be fulfilled:

F > W+ I

in which

F = available vertically directed lifting or supporting force in Newton applied to Yz the patient support system

W = weight in Newton of the patient and the patient support system not carried by the patient I = frictional resistance against movement in engine and hoist construction

This type of hoist or lifting device is suitable for lifting and lowering a patient. However, the vertical movements of the hoist are stiff and inflexible. (Position control).

The present invention provides a simple method and apparatus wherein the above- mentioned disadvantages of the known apparatuses and devices are remedied.

Thus, the present invention provides a method of applying a lifting or supporting force to a person, said method comprising connecting the person to a lever, which is pivotally mounted on a supporting frame member at a pivot point, said person being connected to the lever at a position spaced from said pivot point, and biasing the lever in an upward direction by biasing means, and the method according the invention is characterised in adjusting the lifting or supporting force by changing the moment of force or torque applied to the lever by the biasing means. As explained below, the moment of force applied to the supporting or suspension lever may be changed gradually in many different ways so that the lifting or supporting force may be changed from zero to an amount sufficient to counterbalance the weight of a person.

The biasing means may be of any suitable type and may, for example, comprise a counterweight connected to the lever via a pulley or a similar member. The moment of force applied to the lever may then be changed, for example by changing the point of application of the gravity force to the lever. In the preferred embodiment, however, the biasing means comprise spring means, such as gas springs, coil springs, rubber springs, spiral springs, or combinations thereof.

As an example, the biasing means may extend between a first point of connection to the lever spaced from the pivot point and a second point of connection to the supporting frame member. The biasing means may be of the compression spring type combined with a telescoping rod member and extend below the lever, or be of the tension spring type and extend above the suspension or supporting lever. By such arrangement he lifting or supporting force may, for example, be adjusted by displacing the first point of connection in relation to the lever and/or the second point of connection in relation to the supporting frame member. In other words, the lifting or supporting force may be adjusted by changing the angle defined between the direction of the bias of the biasing means and a line defined by the pivot point and the connecting position.

The present invention further provides an apparatus for lifting or supporting a person, said apparatus comprising a supporting frame member, a lever, which is pivotally mounted on the supporting frame member at a pivot point, connecting means for connecting a person to the lever at a connecting position, which is spaced from said pivot point, and biasing means for biasing the lever in an upward direction, and the apparatus according to the invention is characterised in means for changing the moment of force or torque applied to the lever by the biasing means, so as to allow adjustment of the lifting or supporting force applied to a person connected to the lever by the connecting means.

The means for changing the moment of force or the torque may comprise means for displacing the first point of connection in relation to the lever and/or the second point of connection in relation to the supporting frame member. Such means for changing the moment of force or the torque may comprise a screw spindle mounted rotatably on the supporting frame member or the lever and a nut member co-operating therewith, so that the nut member is displaced axially along the screw spindle when the screw spindle is rotated, one end of the biasing means being connected to the nut member.

In an alternative embodiment the biasing means comprise spring means arranged within an axially extending cavity or bore of the supporting frame member, and the biasing force of the spring means may be transferred to the lever via an elongated connecting member co-operating with a reversing member, such as a chain co-operating with a sprocket wheel, a toothed belt co-operating with a gear, or a wire or belt co-operating with a pulley. The reversing member may, for example be arranged at the upper end of the supporting frame member.

The means for changing the moment of force applied to the lever may, for example comprise means for changing the point of application of the biasing force to the lever. Alternatively or additionally, the means for changing the moment of force applied to lever by the biasing means may comprise means for increasing and decreasing the biasing force applied.

The apparatus according to the invention may not only be used as a lifting device for lifting and transporting a disabled person, but also as a training device. Thus, the person connecting means comprise a seat or saddle, or the like mounted at the free end of the lever, so that a disabled person can sit on the lever with feet resting on the floor.

When the apparatus according to the invention is used as a lifting device, the patient may be supported or carried fully or partially by a sling, vest or other fabric member fastened to the free end portion of the lever.

The frame member of the apparatus may be fastened to a moveable base plate, which may be provided with wheels, rollers, castors, or the like. Alternatively, the frame member may be fixedly mounted on a floor, wall, or ceiling of a room, in which the lifting apparatus is to be used. The frame member may also be mounted on a turntable or pivot disk fixed either directly to the floor of a room or to a mobile chassis. As another possibility, the frame member may be mounted on the frame of a bed or stretcher, and the apparatus may be adapted to lift the stretcher or mattress supporting a patient. The mechanism used for shifting of the point of application of the biasing force to the lifting or suspension lever may be operated manually or by an electrical motor. In the latter case the operation of the motor may be controlled by an automatic electronic control system with or without use of some form of computer or μ-processor software.

When using the apparatus according to the invention as a lifting apparatus the operator may move the patient vertically by manually applying only a small fraction of the total lifting force, thus achieving a near "free flotation" of the lifted patient within a certain vertical interval (force control).

When a person lift of the known type is used for placing a patient on the seat of a chair it is almost impossible to lower the patient into the chair so as to obtain a suitable sitting position of the person. Therefore, the operator or carer has to manually lift the patient into the right sitting position after having lowered the patient by means of the lifting device. However, by using the apparatus according to the invention an adjustable and nearly free floatation may be obtained so that the patient may be gently and effortlessly placed and adjusted into the desired position. Thereafter the floatation support may be gradually diminished and eventually removed all together with practically no effort on the side of the operator or carer.

The invention will now be described more in detail with reference to the drawings, wherein

Fig. 1 is a side view and partially sectional view of an embodiment of the lifting or supporting apparatus according to the invention, Fig. 2 is a diagrammatic side view of the apparatus of Fig. 1 illustrating the principle of the present invention, and

Figs. 3-5 are diagrammatic side views of a second, third and fourth embodiment, respectively, of the apparatus according to the invention.

The various embodiments of the lifting or supporting apparatus according to the invention shown in the drawings all comprise a substantially vertical column or an upright 10 and a lifting or suspension lever 11 having one end portion pivotally connected to the upright 10 at a pivot point 12, so that the lever 1 may swing or pivot around a substantially horizontal axis in relation to the upright 10. A biasing spring device 13 is biasing the lever 11 in an upward direction.

In the embodiment shown in Fig. 1 the upright or column 10 is supported on a stationary or movable base plate 14. The spring device 13 comprises a compression spring arranged within a telescoping device extending between pivots 15 and 16 connected to the lever 11 and the column 10, respectively. The pivot 15 is axially spaced from the pivot point 12 and may be fixedly mounted on the lever 11. The column 10 is tubular and an axially extending screw or threaded spindle 17 is mounted within the inner bore of the column by means of bearings so as to be rotatable, but not axially displaceable in relation to the column 10. A nut member 19, on which the pivot 16 is located, is in engagement with the spindle 17 and is engaging with guide surfaces (not shown) preventing rotation of the nut member 19 in relation to the column 10. This means that the nut member 19 is moved along the spindle 17 when the spindle is rotated. The spring device 13 extends from the pivot 16 formed on the nut member 19 outwardly through an axially extending slot or slit 20. Thus, when the spindle 17 is rotated clockwise and counter-clockwise, the slide or nut member 19 is moved up and down along the length of the spindle 17 or column 10. By moving the nut member 19 the moment of force acting on the lifting lever 11 under the influence of the spring device 13 may be adjusted. Thus, the moment of force is reduced when the nut member 19 is moved upwardly and becomes zero when the pivot 16 coincides with the longitudinal axis of the lever 11 as shown in dotted lines in Fig. 1. The outer end of the suspension lever 11 is provided with an attachment hole or member 21 for fastening suspension means for supporting a person. It is understood that the lifting force applied to a person suspended from the attachment member 21 may be adjusted by rotating the spindle 17 as indicated by an arrow 22. This may be done manually by means of a crank member connected to the upper end of the spindle or by an electric motor, not shown.

By means of the apparatus shown in Fig. 1 an almost free flotation of a person suspended from the supporting lever 11 may be obtained. In principle, for completely free floatation, the vertical lifting force at the attachment member 21 should be constant over the total movement of the lifting lever 11. In reality, however, a slight reduction of the force with increasing elevation may be desirable. The force must definitely not increase with increasing height, as this would result in unstable levitation. For this reason, it may be advantageous to use a gas spring as the biasing spring 13. A gas spring may be attractive because of its very flat, but slightly positive spring characteristic. The resulting lift force characteristic depends on the detailed geometry of the lifting mechanism.

If the gravitational pull acting on the lever 11 at its free end is W, the force applied by the spring device 13 is F, and the dimensions of the apparatus are as shown in Fig. 2, the following equations are valid:

Wχl xsin. C = h x F and h x c = a x b x sin. C

, . , ., _x ,_., , . _Λ αxbxsinCxF which means that Wx Ix sm. C =

and consequently: W =

Ixc

From these equation it is apparent that the lifting force F is proportional to the setting of the spacing b between the pivots 12 and 16.

If the spring force F is assumed to be constant the gravitational pull or the lifting force W will simply be inverse proportional to the length c of the spring device 13, which facilitates a rather attractive floating balance condition over a realistic variation of the spacing c.

In the embodiment shown in Fig. 3 the spring device 13 comprises a tension spring 23, which is arranged within a tubular housing 24. The housing 24 is arranged within the tubular column 10 and may be moved axially in relation thereto in a telescoping manner. The threaded spindle 17 is rotatably mounted in and extends axially into the tubular column 10 from the base plate 14. The spindle 17 is in engagement with the nut member 19, which is mounted in the lower end of the housing 24. Thus, when the spindle 17 is rotated by means of a manual drive or a motor drive, not shown, the housing may be moved axially up and down within the tubular column 10.

The lower end of the tension spring 23 is connected to the housing 24 at 25 and its upper end is connected to one end of a wire or string 26, which is passed over a pulley 27 arranged at the upper end of the housing 24. The other end of the wire or string 26 is connected to the lever 11 at a position 28 spaced from the pivot point 12.

Assuming that the spring constant of the tension spring 23 is k and that the length c of the wire 26 extending between the pulley 27 and the fastening position 28 is equal to the elongation of the spring from its neutral unstressed condition, then the spring force:

F = kxc

and, consequently, in an equilibrium condition the gravitational pull W acting on the lever 11 may be expressed as follows:

kxaxb W =

Since k, a and I are constants the equation shows that the gravitational pull or weight W being supported by the lever 11 is proportional to the setting of the length b by means of the spindle 17 and the nut member 19. However, the lifting or supporting force of the lever 11 is completely independent of the vertical movement of the carried load.

Fig 4. illustrates a simplified version of the embodiment shown in Fig. 3. In Fig, 4 the housing 24 has been omitted, and the lower end of the tension spring 23 has been fastened to the lower end of the tubular column 10 at the connection point 25. The suspension lever 11 is pivotably connected to the column 10 at the pivot point 12 located at the fixed distance b below the top end of the column. The upper end of the tension spring 23 is connected to the wire or string 26, which is passed over the pulley 27. The free end of the wire or string 26 is attached to a slide member 29, which is arranged displaceably along the lever 11 , so that the length a from the pivot point 12 to the position 28 may be adjusted. As an example, the slide member 29 may include a nut member, which may co-operate with a threaded spindle like the spindle 17. Such spindle may be rotated by a crank or other manually operated driving means or by means of an electric motor, not shown. Again balance between the downwardly directed gravitational pull or weight W and the upwardly directed pulling spring force F is achieved when

kxaxb W =

where the spring constant k and the lengths b and I shown in Fig. 4 are fixed values. Thus, the lifting or supporting force W obtainable is proportional to the adjustable length a and independent on the angular position of the lever 11 in relation to its horizontal position.

A further embodiment of the apparatus according to the invention is illustrated in Fig 5. This embodiment is similar to the embodiment shown in Fig. 4 apart from the spring device 13 arranged within the tubular column 10.

In Fig. 5 the tension spring 23 of Fig. 4 has been replaced by a compression spring 30, which is arranged within the tubular column 10 and extends between an annular shoulder or abutment surface formed at the upper end of the column 10 and an abutment member 31 displaceably mounted within the tubular column 10.

The wire or string 26 extends from the slide member 29, via the pulley 27 axially through the tubular column 10 and is connected to the central part of the abutment member 31.

Further wires or strings 32 are attached to opposite ends of the slide member 29 and extend along the suspension lever 11 and over further pulleys 33 and 34 mounted on the column 10 just below the pivot of the lever 11 and at the free end of the lever 11 , respectively. The wires 32 are co-operating with a winch indicated at 35 and located at some convenient location on the column 10. By rotating this winch 35 the slide member may be moved along the lever 11. Thus the position of the slide member 29 on the lever 11 may be controlled and held in an adjusted position by the arrangement including the winch 35, the pulleys 33 and 34, and the wires 32. A damping device 36 is preferably arranged in the lower part of the tubular column 10 beneath the spring device 13. In an simple embodiment the damping device 36 comprises a body of viscous liquid, such as oil, arranged in the lower end of the column 10, an a non-sealing piston, such as the abutment member 31 , moving axially in the liquid body when the apparatus is used. Thus, the tilting or pivoting movements of the lever 11 is suitable damped.

Also in this case balance between the downwardly directed gravitational pull or weight W and the upwardly directed pulling spring force F is achieved when

kxaxb W =

where the spring constant k and the lengths b and I shown in Fig. 5 are fixed values. Thus, the lifting or supporting force W obtainable is proportional to the length a, which is adjustable by means of the winch 35. The winch may be rotated manually or by means of an electric motor, not shown.

In the embodiment illustrated in Figs 1 and 2 the supporting or lifting force W is increasing progressively when the load or person supported by the lever 11 is lowered. Thereby the person suspended may be "free floating". In the embodiments illustrated in Figs. 3-5, however, the lifting or supporting force W is constant in all elevations or angular positions of the lever 11.

The apparatus according to the present invention may be used for lifting or supporting a disabled person. Thus, the person to be lifted may be lifted by means of a sling or strap, which is connected to the attachment member 21 at the free end of the lever 11 , and thereafter the person may be lifted or supported by rotating the spindle 17 (Figs. 1-4) or the winch 35 (Fig. 5), so as to tilt the lever 11 in an upward direction.

As mentioned above, the spindle 17 and the winch 35 may be rotated manually or by an electric motor. In the case of a motorised spindle control it is quite likely that a carer may find it preferable to keep the lifting force slightly higher than the weight of the patient being lifted. The carer will then have to pull the lever 11 slightly downwardly to position the patient properly. This is more convenient than if the carer to lift the lever slightly upwards. When the patient has been properly seated a mere touch of a push-button may cause a motor driven lifting mechanism to release the lifting force to finalise the transfer of the patient. Although the apparatus according to the invention has so far been described primarily as a hoist used for lifting a patient from one place to another it should be understood that the free floatation principle is equally applicable for completely or partly supporting a person, for example while the person is sitting on a seat or a saddle formed on or connected to the free end of the lever 11. When the apparatus is made mobile, for example by providing the base plate 14 with wheels, such as castors, it may form a very important training device. Thus, the patient may sit on the seat or saddle and have only a selected part of his weight supported by the apparatus while the remaining part of his weight is supported by his legs when he is walking and moving around. In this manner the load being supported by the patient's legs may be gradually increased as his constitution permits. As mentioned above, the mobility of the patient may be obtained through passive castors. Alternatively, a motorised, full freedom drive system may be used.

It should be understood that various changes and modifications of the embodiments described above could be made within the scope of the present invention as defined in the appended claims. As an example, it is within the scope of the invention to drive the lifting force adjusting mechanism by an electric motor and to have the setting or adjustment controlled automatically. Such control may, for example, be performed by computer or μ-processor software aiming for some specific balance condition, which itself may be a function of the lifting height, for example, thereby dynamically achieving some arbitrarily specified lift force characteristic. It is also envisaged that a read out of the balancing force may indicate the weight of the person being lifted.

The spring device 13 may comprise any kind of spring, such as a coiled metal spring, a coiled metal spring extended by a string or rope guided over rollers, or an elastic rubber band.

Claims

1. A method of applying a lifting or supporting force to a person, said method comprising connecting the person to a lever (11), which is pivotally mounted on a supporting frame member (10) at a pivot point (12), said person being connected to the lever at a position (21) spaced from said pivot point (12), and biasing the lever (11) in an upward direction by biasing means (13), characterised in adjusting the lifting or supporting force (W) by changing the moment of force or torque applied to the lever (11) by the biasing means (13).

2. A method according to claim 1 , wherein the biasing means (13) comprise spring means (23,30).

3. A method according to claim 1 or 2, wherein the biasing means (13) extend between a first point (15) of connection to the lever (11) spaced from the pivot point (12) and a second point (16) of connection to the supporting frame member (10).

4. A method according to claim 3, wherein the lifting or supporting force (W) is adjusted by displacing the first point (15) of connection in relation to the lever (11) and/or the second point (16) of connection in relation to the supporting frame member (10).

5. A method according to claim 3 or 4, wherein the lifting or supporting force (W) is adjusted by changing the angle defined between the direction of the bias (F) of the biasing means (13) and a line defined by the pivot point (12) and the connecting position (21).

6. An apparatus for lifting or supporting a person, said apparatus comprising a supporting frame member (10), a lever (11), which is pivotally mounted on the supporting frame member (10) at a pivot point (12), connecting means for connecting a person to the lever (11) at a connecting position (21), which is spaced from said pivot point (12), and biasing means (13) for biasing the lever (11) in an upward direction, characterised in means (17,19;29;35) for changing the moment of force or torque applied to the lever (11) by the biasing means, so as to allow adjustment of the lifting or supporting force (W) applied to a person connected to the lever (11) by the connecting means..

7. An apparatus according to claim 6, wherein the biasing means (13) comprise spring means (23,30).

8. An apparatus according to claim 7, wherein the biasing means (13) extend between a first point (15) of connection to the lever (11) spaced from the pivot point (12) and a second point (16) of connection to the supporting frame member (10).

9. An apparatus according to claim 8, wherein the means for changing the moment of force or the torque comprise means (17,19) for displacing the first point (15) of connection in relation to the lever (11) and/or the second point (16) of connection in relation to the supporting frame member (10).

10. An apparatus according to claim 6 or 9, wherein the means for changing the moment of force or the torque comprise a screw spindle (17) mounted rotatably on the supporting frame member (10) or the lever (11) and a nut member (19) co-operating therewith, so that the nut member is displaced axially along the screw spindle when the screw spindle is rotated, one end of the biasing means being connected to the nut member.

11. An apparatus according to claim 9 or 10, wherein the biasing means (13) comprise spring means (23,30) arranged within an axially extending cavity or bore of the supporting frame member (10), the biasing force (F) of the spring means being transferred to the lever (11) via an elongated connecting member (26).

12. An apparatus according to claim 11 , wherein the connecting member is a line or wire (26) passing a reversing pulley (27) mounted at the upper end of the frame member.

13. An apparatus according to claim 11 or 12, wherein the means for changing the moment of force applied to the lever (11) comprise means (29.32,35) for changing the point of application of the biasing force (F) to the lever (11).

14. An apparatus according to any of the claims 6-13, wherein the means for changing the moment of force applied to lever (11) by the biasing means (13) comprise means (17,19,24, Fig. 3) for increasing and decreasing the biasing force applied.

15. An apparatus according to any of the claims 1-14, wherein the person connecting means comprise a seat or saddle mounted at the free end of the lever (11).