AU5829694A - Improvements in and to a mobile patient lifter - Google Patents

Description

IMPROVEMENTS IN AND TO A MOBILE PATIENT LIFTER

This invention relates to an improved mobile patient lifter used for lifting and transporting immobile patients.

Many different forms of mobile patient lifters are known to the applicant, such lifters having been developed over a number of years for the purpose of moving patients to and from beds, chairs and baths, or lifting them from a reclined or horizontal position on the ground. Whilst such units operate generally satisfactorily, one of their drawbacks is their lack of versatility in that they cannot be used with different patient support attachments which are available on the market and which are needed depending on the type of lift and manoeuvre to be carried out. For example most patient lifters known to the applicant comprise a mobile chassis or base frame, a mast or column extending upwardly from the base at one end thereof, a jib arm extending away from the mast or column and which carries at its outer free end attachment means for attachment of a patient support assembly, e.g. a sling, cradle or chair frame, and actuator means operatively interconnected between the jib arm and the mast or column for effecting raising and lowering of the jib arm and in turn the patient support assembly. In some instances, the jib arm is permanently pivotally attached to the upper end of the mast or column, whilst in other cases, the arm is fixedly secured to a carriage or traveller which is guided for vertical movement along the mast or column internally thereof. In some other arrangements, the mast or column assembly itself is adjustable in height.

It is an object of the present invention to provide an improved mobile patient lifter which is of versatile design in that it is readily adapted for use with a range of patient support attachments, and thus capable of performing a number of different patient lifting manoeuvres. It is another object of the present invention to provide an improved mobile patient lifter which permits a range of patient support attachments to be quickly and readily attached thereto, and which allows the lifter to be converted from one mode of use to another relatively quickly.

It is a still further object of the present invention to provide an improved mobile patient lifter which is easy to assemble and disassemble for transporting, and as well easy to maintain and service.

It is a still further object of the invention to provide a mobile patient lifter having a simple, efficient mast assembly for effecting the lifting/lowering movement of the patient support attachment connected thereto.

Broadly according to this invention therefore, an improved mobile patient lifter comprises a mobile chassis, an upstanding mast assembly mounted on the chassis adjacent the rear thereof, said mast assembly comprising a vertical inner mast and a vertical outer mast guided for vertical movement with respect to the inner mast, actuator means for effecting up and down movement of the outer mast relative to the inner mast, a movable carriage on the outer mast and guided for vertical movement externally along the length thereof, lifting means connected to the carriage for moving the carriage with respect to the outer mast, and a lifter arm extending laterally from the carriage and detachably connected thereto, said lifter arm being arranged to move with the carriage upwards or downwards along the outer mast. The outer free end of the lifter arm, when the lifter is in use, has detachably connected thereto a patient support cradle, sling, chair or the like. By having a detachable connection, different types of support devices can be readily attached to and suspended from the arm. Preferably, the actuator means comprises a linear actuator extending upwardly through the inner and outer masts and having its upper end connected to the upper end of the outer mast.

Preferably, the lifting means comprises at least one elongate member, eg a strap or cable, which has one end anchored to the carriage and its other end anchored to the stationary inner mast, the elongate member passing over a roller or sheave carried at or near the upper end of the outer mast, whereby any upward or downward movement of the outer mast results in an additive component of movement of the carriage with respect to the outer mast. This allows the overall height of the lifter to be reduced for a given amount of travel of the lifter arm.

Preferably, the carriage is provided with a pair of rollers on opposite sides thereof, one adjacent an upper edge thereof, the other adjacent a lower edge thereof, said rollers rollingly engaging respective front and rear surfaces of the outer mast as the carriage moves therealong.

Preferably, the chassis comprises an inverted U-shaped transversely extending base frame member which interconnects a pair of spaced apart, horizontal transversely aligned elongate side rails which project forwardly of the base frame member, said base frame member having a bridging portion which is spaced above the ground by a distance sufficient to allow the mobile lifter to move lengthwise of and be positioned over a patient when lying on the ground. Preferably, each of the side rails is supported at its opposite ends by castor wheels, and the rails are pivotally mounted to enable the rails at the forward end of the chassis to be spread apart.

Preferably, the lifter arm is connected to the carriage by quickly detachable connection means . With this arrangement, an operator is able to very quickly detach the cantilevered lifter arm from the mast assembly, and attach a different accessory suspension arm for suspending an accessory therefrom.

Preferably the quickly detachable connection means comprises a pair of spaced keyhole engaging lugs secured at the inner end of the lifter arm near its upper edge, and which slidably engage within transversely aligned, vertically disposed keyhole shaped openings which are formed in the front wall of the carriage near its upper end. This allows the accessory attachment lifter arm to be easily and quickly mounted on the carriage, and in turn disengaged therefrom. To further secure the fitment of the lifter arm, its lower end may slidably locates in a slot-like opening formed adjacent the lower end of the carriage.

Preferably a quick release safety catch, e.g. a spring- loaded latch member, is provided for releasably locking the arm in position and to prevent the attachment lifter arm lifting out under pressure during use of the machine.

In order to more fully explain the present invention, an embodiment is described hereunder in some further detail with reference to and as illustrated in the accompanying drawings, wherein:

Fig 1 is a rear elevational view, partly sectioned, of a mobile patient lifter according to this embodiment;

Fig 2 is a partly sectioned, side elevational view of the lifter shown in Fig 1 with the outer mast, along with the patient support cradle shown in a lowered position;

Fig 3 is a view similar to Fig 2 (but unsectioned) showing the outer mast in an elevated position; Fig 4 is a front elevational view of the lifter shown in Fig 1 in its lowered position (but without the lifter arm) ;

Fig 5 is a plan view of the lifter shown in Fig 1, with one of the sides of the base frame swung to an outwardly diverging position; whilst

Fig 6 is a fragmentary perspective view of the lifter having attached thereto an alternative accessory attachment lifter arm designed to suspend an invalid wheelchair therefrom.

According to this embodiment, a mobile patient lifter 10 comprises a mobile chassis or base frame 11, an upstanding mast assembly 12 projecting upwardly from the base frame 11 adjacent its rear end, a lifter arm 13 projecting forwardly from the mast assembly 12, and a patient support device 14 which in this embodiment comprises a cradle assembly, suspended at the outer free end of the lifter arm 13. This arrangement is generally in accord with known prior art.

The mast assembly 12 comprises a fixed tubular inner mast 15 and a movable hollow outer mast 16 which is arranged to travel up and down along the inner mast 15 and being guided thereby, the movement of the outer mast 16 being effected by means of a known mechanical actuator 20 of the screw type housed within the inner mast 15 and having its upper end coupled to the upper end of the mast 16. In this embodiment the actuator 20 is operated by means of an electric motor 17 housed in housing 18, the motor 17 being energised by means of a battery housed in battery housing 19 supported with respect to the inner mast 15. The battery forms part of a detachable battery pack, whilst the motor housing 18 is removable for ease of maintenance and safety.

The outer mast 16 is of hollow rectangular cross- sectional shape being formed of two oppositely facing channel halves which are joined together to form a pair of planar vertical guide surfaces 21, 22 extending along the front and rear walls respectively of the outer mast 16. A movable carriage 23 travels upwards and downwards along the length of the outer mast 16 guided by means of front and rear transverse guide rollers 24, 25 which rollingly engage the front and rear guide surfaces 21, 22 on the mast 16, the rollers 24, 25 being disposed along diagonally opposite edges of the carriage 23. Additionally, there are provided side guide rollers (not shown) on the carriage 23 which co-operate with the opposite side walls of the outer mast for minimising lateral "slop" and to assist in the smooth travel of the carriage 23 along the outer mast 16. The surfaces 21, 22 of the outer mast 16 act as bearing surfaces for the rollers 24, 25.

A horizontally mounted transversely extending roller 28 is carried by the outer mast 16 adjacent its lower end and rollingly engages against the front wall of the inner mast 15 for guiding the outer mast 16 as it moves in either an upwards or downwards direction. Preferably, the inner mast 15 is also provided with a transverse guide roller (not shown) adjacent its top end and which is designed to rollingly contact the inner surface of the rear wall of the outer mast 16.

At opposite sides of the outer mast 16, there is provided a pair of pulley lifting straps 29 which are operatively coupled between the upper end of the carriage 23, and the upper end of the fixed inner mast 15, each strap 29 passing over a freely rotatable roller 30 mounted at the upper end of the outer mast 16. In this embodiment, the upper end of the mast 16 is closed by means of a fixed end cap 31 which rotatably supports the rollers 30 internally of the mast 16. Thus, in use, when the actuator 20 is operated, the actuator rod, via an extension rod 32 coupled to the actuator rod, pushes against the end cap 31 on the mast 16 to thereby elevate the mast 16 with respect to the inner mast 15 and in turn simultaneously cause the carriage 23 to travel upwardly along the outer mast 16 by means of the lifting action provided by the two lifting straps 29 which are anchored to the top of the inner mast 15. This movement also works in reverse as the actuator rod is retracted in a downwards direction. In this embodiment the actuator has a stroke of approximately 625mm, and together with a travelling distance of 625mm of the carriage 23 upwardly along the outer mast, provides an overall lift for the arm 13 of 1250mm. It will be realised that the arm 13 is lifted through a vertical distance which corresponds to the additive motions of the carriage 23 and the outer mast 16.

The arrangement of the flexible lifting straps 29 provides a safety advantage should the lifter arm 13 encounter an obstacle during its lowering movement. If this should occur, although the outer mast will continue to go down (due to the downward motion of the actuator 20), the carriage 23 and in turn the arm 13 will remain stationary and remain so until the obstruction is removed. The flexible straps 29 will simply collapse by forming a number of folds.

The lifter arm 13 is detachably connected to the carriage 23 by means of a quick release slide connection which allows the arm 13 to be quickly and readily detached from the carriage 23 and the fitment of an alternative patient support lifter arm. It will of course be appreciated that a number of different patient support devices are required so as to provide alternative forms of support for patients who are to be supported by the lifter 10, this depending on the nature of the disability of the patient. In this embodiment, the lifter arm 13 has a vertically extending mounting bracket plate 34 at its inner end, the bracket plate 34 being provided with a pair of rearwardly projecting lugs 35 which lockingly engage within keyhole shaped openings 36 formed in the front wall 37 of the carriage 23 adjacent the upper corners thereof. To further assist the location of the arm 13, the lower end of the bracket 34 is designed so that its two bottom corner portions can slidably locate in slot-like channels 38, formed at the two bottom corners of the front wall 37 of the carriage 23.

It will of course be appreciated that there are several other known suitable quick-release connection means which could be used to detachably connect the arm 13 to the carriage 23. It is desirable that the lifter arm 13 be designed so that bearing contact with the carriage is made at upper and lower spaced apart attachment regions .

It is thus a very simple operation to connect the lifter arm 13 to the carriage 23 or detach it therefrom. The lifter arm is preferably of lightweight material to allow it to be easily handled by an operator, e.g. a nurse.

Preferably a safety lock device (not shown) is provided on the carriage 23 for releasably locking the arm 13 in its engaged position with the carriage 23, to thereby ensure that the arm does not release itself inadvertently from the carriage when in use. The locking device may simply be a spring-loaded latch mechanism.

The patient support device 14, in this embodiment, comprises a cradle assembly of known construction, and is suspended from the free end of the lifter arm 13 by means of a vertical suspension bolt 40 which allows the cradle to rotate about a vertical axis . The cradle 14 is arranged to have a sling (not shown) attached thereto. To assist the handling of the lifter 10 by an operator, a handle assembly is attached to the outer mast 16 and can be raised and lowered therewith. In this embodiment the handle assembly comprises a pair of vertical transversely spaced apart hand engaging handle bars 41, each of which is connected at its upper end to the top cap 31 of the outer mast 16 by a U-shaped bridging rod 42, whilst the lower ends of the handle bars 41 are detachably connected to respective opposite sides of the outer mast 16 by means of separate connector rods 43.

The top cap 31 on the outer mast 16 can be removably mounted to allow same to be removed for service and maintenance purposes. To remove the top cap 31, the handle assembly is collapsed by separating the component parts 41, 42, 43.

Referring to Fig 5 of the drawings, the chassis or base frame 11 comprises a bridging frame 45, and a pair of forwardly projecting side rails or legs 46 which are pivotally mounted at their rear ends to the underside of the bridging frame 45 to allow each of the legs 46 to rotate about a vertical axis, and to permit the space between the legs 46 to be adjusted. Each of the legs 46 is supported at its forward end by a front ground-engaging support castor 47, whilst its rear end is connected to a vertical pivot pin 49. The rear end of the base frame is supported by a rear castor support wheel 48. The width adjustment of the base frame 11 by virtue of the pivotally mounted legs 41, allows the legs to go either side of chairs, a bath or any other object to achieve a safe and practical position when the machine is being operated.

The bridging frame 45 comprises an inverted U-shaped bridging member 50 which is designed to allow the lifter 10 to be positioned over a patient when lying on the ground or floor without inconveniencing the patient whilst being positioned in the patient support cradle 14. In this embodiment the central portion of the bridging member 50 is shaped to house the base of the actuator 20 which is mounted on a pivot for flexibility during use.

In this embodiment, each of the legs 46 is provided with an electric solenoid locking device 52 designed to releasably lock the leg against pivotal movement in all operating positions thereof.

As shown in Fig 1 of the drawings, the underside of the bridge member 50 is provided with an actuator pivot support plate 54 centrally thereof, to support the base of the actuator 20 which, as stated above, is pivotally mounted to provide flexibility and easy removal for service and maintenance thereof.

Referring to Fig 6, the lifter arm 13 has been removed from the carriage 23 and replaced by an accessory attachment arm 55 designed to releasably suspend an invalid chair 56 therefrom.

Preferably the lifter 10 is constructed of carbon fibre, although it will be appreciated that it can be constructed from other suitable materials, e.g. aluminium, steel. Carbon fibre however provides a wide range of advantages including strength, rigidity, lightness, good vibration dampening qualities, chemical and corrosive resistance and virtually unlimited life span.

Preferably, the electrically operated actuator 20 and solenoids 52 are operated by means of a hand-held remote control unit (not shown) carried on an extendible cord, thereby enabling the operator to operate the machine from virtually any position. This also allows the control unit to be operated by the patient himself. It is an advantage of the present invention that the lifter allows an operator to very quickly and easily detach the lifter arm and its associated patient support device, from the carriage which moves up and down along the outer mast of the mast assembly, and to in turn attach an alternative accessory attachment arm, it being appreciated that there are a number of different patient support devices which are available and which are required depending upon the patient manoeuvre to be performed by the lifter. This feature allows the present lifter assembly to be used as a multi¬ purpose unit - rather than having to stack separate machines for handling different patient transfer requirements.

Claims (17)

The claims defining the invention are as follows:

1. A mobile patient lifter comprising a base frame, an upstanding mast assembly mounted on the base frame, said mast assembly comprising a vertical inner mast and a vertical outer mast guided for vertical movement with respect to the inner mast, actuator means for producing said vertical movement of the outer mast, a movable carriage on the outer mast and guided for vertical movement externally along the length of said outer mast, lifting means operatively coupled to the carriage for producing said vertical movement of the carriage with respect to the outer mast, and a lifter arm extending laterally from the carriage and detachably connected thereto, said lifter arm being arranged to move with the carriage upwards or downwards along the outer mast.

2. A mobile patient lifter according to claim 1 wherein said lifting means effects said movement of the carriage along the outer mast simultaneously with the movement of the outer mast with respect to the inner mast.

3. A mobile patient lifter according to claim 2 wherein said lifting means comprises at least one elongate member which at one end is connected to said carriage, its other end being anchored to said inner mast, said elongate member passing over a freely rotatable roller or sheave carried at or near the upper end of said outer mast, arranged so that any upward or downward movement of the outer mast results in an additive component of movement of the carriage with respect to said outer mast.

4. A mobile patient lifter according to claim 3 wherein the or each said elongate member comprises a flexible lifting strap.

5. A mobile patient lifter according to claim 4 wherein there are two said lifting straps located adjacent opposite sides of said outer mast, each said lifting strap passing over a respective said freely rotatable roller.

6. A mobile patient lifter according to any one of the preceding claims wherein said lifter arm is detachably connected to said carriage by quick release attachment means .

7. A mobile patient lifter according to claim 6 wherein said quick release attachment means comprises a plurality of transversely spaced apart lugs secured to and projecting rearwardly from the inner end of the lifter arm near its upper edge, each said lug lockingly engaging within a respective slotted opening formed in the front wall of said carriage near its upper end.

8. A mobile patient lifter according to any one of the preceding claims wherein said actuator means comprises a linear actuator extending upwardly through the inner and outer masts and having its upper end connected to the upper end of said outer mast.

9. A mobile patient lifter according to any one of the preceding claims wherein said carriage is guided along the length of said outer mast by means of a pair of horizontal transversely extending rollers, one of which is located adjacent the lower edge of the front wall of the carriage, the other being located adjacent the upper edge of the rear wall of said carriage, said rollers rollingly engaging respective front and rear surfaces of said outer mast as the carriage moves therealong.

10. A mobile patient lifter according to any preceding claim further comprising an operator handle assembly attached to said outer mast and movable therewith.

11. A mobile patient lifter according to claim 10 wherein said handle assembly comprises a pair of transversely spaced apart vertical handle bars, one to each side of the mast assembly and spaced rearwardly thereof, each said handle bar being connected at its opposite ends to said outer mast by upper and lower connector rods .

12. A mobile patient lifter according to any preceding claim wherein said base frame comprises a pair of transversely spaced apart horizontally aligned elongate side rails, a bridging frame member interconnecting said side rails near their rear ends, said bridging frame member supporting said mast assembly centrally thereof and being spaced above the ground by a distance sufficient to allow the bridging frame member to be positioned over a patient when lying on the ground.

13. A mobile patient lifter according to claim 12 wherein each said side rail is supported at its opposite ends by castor wheels .

14. A mobile patient lifter according to claim 13 wherein at least one of said rails is pivotally mounted on the underside of said bridging frame for pivotal movement about a vertical axis to enable the distance between said rails at the forward ends thereof to be adjusted.

15. A mobile patient lifter according to claim 14 wherein each said side rail has operatively associated therewith an electric solenoid locking device for releasably locking the said rail against pivotal movement in all operating positions thereof.

16. A mobile patient lifter according to either claim 6 or claim 7 wherein the inner end of said lifter arm, when attached to said carriage, has its lower end slidably engaging within an upwardly opening channel extending at least partly across the front wall of the carriage adjacent the lower edge thereof.

17. A mobile patient lifter substantially as hereinbefore described with reference to and illustrated in the accompanying drawings.