GB2154440A

GB2154440A - Lifting seat

Info

Publication number: GB2154440A
Application number: GB08429490A
Authority: GB
Inventors: John Meredith Thring
Original assignee: JAYBE Ltd
Current assignee: JAYBE Ltd
Priority date: 1984-02-27
Filing date: 1984-11-22
Publication date: 1985-09-11
Also published as: GB8429490D0; GB8405019D0

Abstract

A lifting seat comprises a base portion 11, a seating portion 12 pivotally connected to portion 11 for movement between a seating position and a tilted position, resilient biasing means arranged to bias the portion 12 towards the tilted position, and a releasable latch arrangement for holding the portion 12 in the seating position against the action of the biasing means, which comprises leaf springs 14 arranged to act between the portions 11 and 12, and respective disabling means associated with each spring and operable from externally of the seat to render the corresponding spring inoperative. The disabling means comprises a threaded fastener 23 which can engage with a preformed thread in a respective spring 14, or a captive nut 24 mounted on the spring, fastener 23 being engageable with the respective spring when portion 12 is moved to the seating position. When incorporated in a wheelchair, the seat may comprise a turntable arrangement to allow transfer of a person to a vehicle. <IMAGE>

Description

SPECIFICATION Lifting seat This invention relates to a lifting seat for use by elderly and/or infirm people, the seat comprising a base portion, a seating portion pivotally connected to the base portion for movement between a substantially horizontal seating position and a tilted position, resilient biasing means arranged to bias the seating portion towards the tilted position, and a releasable latch arrangement for holding the seating portion in the seating position against the action of the biasing means.

Lifting seats are well known for assisting people to move between sitting and standing positions, and vice versa, the resilient biasing means applying a gentle lifting movement to the seat of the user upon release of the latch arrangement in order to assist standing-up. Similarly, a user moving from a standing position to a seating position can have his descent partly cushioned by resilient yielding of the seat portion, when in the tilted position, to the seating position.

It will be appreciated that the seating portion and the base portion are normally supplied fuliy upholstered, so that the operating parts of lifting seats are not normally readily accessible. It should also be noted that the required lifting force provided by a lifting seat can vary substantially from one person to another, or indeed can vary for a particular user over a period of time due to alteration in weight and/or diminishing mobility.

Therefore, it is desirable to provide a lifting seat construction in which it is readily possible for the lifting force to be adjusted without requiring any dismantling or disassembly of the lifting seat, or removal of upholstery.

According to the invention there is provided a lifting seat comprising a base portion, a seating portion pivotally connected to the base portion for movement between a substantially horizontal seating position and a tilted position, resilient biasing means arranged to bias the seating portion towards the tilted position, and a releasable latch arrangement for holding the seating portion in the seating position against the action of the biasing means, in which the resilient biasing means comprises a plurality of leaf springs arranged to act between the base portion and the seating portion, and respective disabling means associated with each of at least some of the leaf springs and operable from externally of the lifting seat in order to renderthe corresponding leaf spring inoperative.

Thus, it is possible to provide a lifting seat which can readily be adjusted in order to suit a wide range of required lifting forces by selective bringing-intoaction, or disabling, of one or more of the leaf springs.

It is preferred that each leaf spring is rigidly held at one end in cantilever manner on the base portion, and is slidingly engageable at its opposite end with a slider provided on the underside of the seating portion.

Conveniently, the slider comprises a transverse member in the form of a bar or rod which is engaged simultaneously by all of the operative leaf springs. The transverse member is spaced an appreciable distance from the pivot axis of the seating portion on the base portion, so as to provide a turning moment under the action of the operative leaf springs to generate the required lifting force.

The pivot axis may be provided by a transverse rod carried by a rigid metal frame secured to the base portion, and the seating portion may have a plurality of spaced apart brackets slidably and pivotally mounted on the transverse rod.

The number of leaf springs which are provided will depend upon the required number of increments of lifting force adjustment, and the spaces available. A preferred number is seven leaf springs, and evidently this will provide a range of six possible adjustments of upward lifting force, (assuming each leaf spring has a respective disabling means) from a basic lifting force provided by a single leaf spring. The possibility of six upward adjustments assumes that each leaf spring provides an equal lifting action. However, evidently, if desired, a set of leaf springs may be provided having different spring actions, in which case a large number of adjustments may be provided by suitable selection of leaf springs which are to be disabled.

It may be desirable to provide the lifting seat with a permanently effective biasing arrangement to provide a basic minimum lifting force to which can be added, as required, the lifting action of one or more of the leaf springs. Conveniently, this permanently effective biasing arrangement may be provided by an arrangement of one or more torsion springs arranged on the transverse rod which forms the pivot axis.

The disabling means for each leaf spring is preferably of relatively simple, but reliable construction, and may comprise a threaded fastener which can be taken through the base portion from the underside thereof and into engagement with a captive nut, or preformed internal thread in the leaf spring. When the seating portion is in the seating position, all of the operative leaf springs will be pressed downwardly by the slider on the underside of the seating portion, and it is a simple matter to engage one or more threaded fasteners with the leaf spring(s) which is/are to be disabled. Upon release of the latch arrangement, only the remaining nondisabled leaf springs can then apply a composite lifting action (plus the minimum provided by the permanent biasing arrangement, if provided).

The lifting seat of the invention may be supplied as an integral part of a newly manufactured chair, or may be supplied for application to existing chairs.

The lifting seat may also be adapted for use in "wheel chairs", either as original equipment, or as a unit to convert existing wheelchairs.

The releasable latching arrangement may take any one of the forms known per se for lifting seats, preferably being such as to be automatically selflatching upon movement of the seating portion to the seating position. Conveniently, also the latching arrangement may be arranged in such a way as to minimise the risk of accidental operation e.g. by children. Thus, the latching arrangement may be such as to have a special mode of operation e.g. the latching arrangement can only be released after exertion of a small additional downward force on the seating portion.

Evidently, as the seating portion moves from its seating position to the tilted position, it carries out arcuate movement about the pivot axis.

Conveniently, a limit stop is provided to determine a required range of angular movement, and this limit stop may be adjustable to suit requirements.

When the lifting seat of the invention is applied to a wheel chair, it may be desirable to provide a pivotal support arrangement which will permit the entire lifting seat to pivot relative to the wheelchair about a substantially vertical axis. The support arrangement may comprise "turntable" arrangement, which will permit pivotal movement of the lifting seat relative to the wheelchair structure through at least a limited angle.

This pivoting feature, referred to above, will be of assistance in the transfer of a person between a wheelchair and a vehicle seat. It is a commonly experienced problem that there is only a limited room for manoeuvre for transferring a patient from a wheelchair to a vehicle seat, since the wheelchair normally has to be brought sufficiently close to the vehicle and within the arc of movement of the usual vehicle door. Having placed the wheelchair in position adjacent to the vehicle, the pivotal support arrangement referred to above can be operated, to then allow lifting of the patient under the action of the lifting seat in the most convenient direction to suit subsequent transfer to the vehicle seat, and vice versa.

Embodiments of lifting seat according to the invention will now be described in detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side view of a base portion and a pivotally connected seating portion of a lifting seat according to the invention; Figure 2 is a plan view of the base portion shown in Figure 1; Figure 3 is a perspective view of the lifting seat, taken generally in the direction of the arrow X in Figure 1; and Figure 4 is a side view, similar to Figure 1, of an alternative embodiment of lifting seat according to the invention.

Referring now to Figures 1 to 3 of the drawings, there is shown in generally diagrammatic illustration the essential features of a lifting seat according to the invention. The lifting seat, as illustrated, will be provided with suitable upholstery, and means for mounting the lifting seat in a chair, or "wheelchair" as original equipment, or as supplementary equipment to be applied to existing chairs and wheelchairs.

The lifting seat is designated generally by reference numeral 10 and is intended primarily for use by the eiderly and/or infirm people, in order to assist transfer between standing and seating positions. The lifting seat 10 comprises a base portion 11, and a seating portion 12 which is pivotally connected to the base portion 11 for movement about a substantially horizontal pivot axis 13 provided at the forward end of the lifting seat. The seating portion 12 is pivotable about the axis 13 between a substantially horizontal seating position and a tilted position, as shown in Figure 1.

Although not shown, a limit stop, which may be adjustable, is provided in order to determine the limit to the arc of movement of the seating portion 12 from the seating position to the tilting position.

A releasable latch arrangement will be provided in order to hold the seating portion 12 in the seating position, and this may take the form of any of the conventional constructions used in lifting seats.

Resilient biasing means is arranged to bias the seating portion 12 towards the tilted position, and the releasable latch arrangement holds the seating portion 12 in the horizontal seating position against the action of the biasing means.

The resilient biasing means comprises an arrangement of a plurality of leaf springs which are arranged to act between the base portion 11 and the seating portion 12. For convenience of illustration, only one leaf spring 14 is shown in detail in the drawings, though additional leaf springs are shown in dashed outline in Figure 2. The construction and arrangement of the leaf springs 14, and respective disabling means therefor will now be described in more detail below, with reference to the single leaf spring 14 shown in the drawings, it being understood that this will apply also to all of the others.

The leaf spring 14 is rigidly held at one end 15 in cantilever manner on the base portion 11 by being secured by a pair of threaded fasteners 16. At the opposite end 17 of the leaf spring 14 there is sliding engagement with a slider 18 provided on the underside of the seating portion 12. The slider 18 comprises a transverse member in the form of a bar or rod which is engaged simultaneously by all of the non-disabled leaf springs. The slider 18 is carried by a pair of angle brackets 19 secured to the underside of the seating portion 12. It will be noted, particularly from Figure 1, that the slider 18 is placed an appreciable distance from the pivot axis 13, whereby the upward turning moment applied by the leaf springs 14 to the seating portion 12 via the slider 18 can exert the lifting force on the seat of the user who is sitting on the seating portion 12.

As will be seen in more detail in Figure 3, the pivot axis 13 is formed by a transverse rod 20 which is carried by a rigid metal frame 21 secured to the base portion 11. The seating portion 12 is pivotally mounted on the transverse rod 20 by means of a number of spaced apart brackets 22 which are secured to the underside of the seating portion 12 and which are slidably and pivotably mounted on the transverse rod 20.

Referring again to Figure 1, all of the non-disabled leaf springs 14 can move to take up the position shown therein, in order to move the seating portion 12 to the tilted position upon release of the latch arrangement. Downward movement of the seating portion 12 back to the seating position will be against the resilient resistance of the effective leaf springs 14, Figure 1 showing in dashed outline the arcuate path of movement of the free ends of the leaf springs 14 and of the slider 18.

As shown in Figure 2, seven leaf springs 14 are provided, and respective disabling means is associated with each of at least some of the leaf springs 14. Preferably, each leaf spring has its own disabling means. By providing seven leaf springs, evidently this will provide a range of six possible adjustments of upward lifting force from a basic lifting force provided by a single leaf spring.

However, it may be desirable to provide the lifting seat with a permanently effective biasing arrangement (not shown) to provide a basic minimum lifting force to which can be added, as required, the lifting action of one or more of the leaf springs. The permanently effective biasing arrangement may comprise an arrangement of one or more torsion springs arranged on the transverse rod 20.

The disabling means for each leaf spring is of relatively simple, but reliable construction, and in the illustrated embodiment comprises a threaded fastener 23 which is taken through the base portion 11 from the underside thereof into engagement with a captive nut 24 on the associated leaf spring 14, or into a pre-formed internal thread (not shown) in the leaf spring. When the seating portion 12 is in the seating position, all of the operative leaf springs 14 will be pressed downwardly by the slider 18, and it is a simple matter to engage one or more of the threaded fasteners 23 with the associated leaf spring(s) which is/are to be disabled. Upon release of the latch arrangement, only the remaining nondisabled leaf springs can apply the composite lifting action to the seating portion, plus the minimum provided by the permanent biasing arrangement, if provided.

When the lifting seat is designed for wheelchair, use, it may be desirable to provide a "turntable" arrangement whereby the entire lifting seat 10 can be bodily rotated about a substantially vertical axis relative to the main structure of the wheelchair. This may facilitate transfer of a patient to and from the wheelchair in awkward locations.

Referring now to Figure 4 of the drawings, there is shown an alternative embodiment of lifting seat according to the invention, in which parts corresponding with those already described and illustrated in Figures 1 to 3 bear the same reference numerals, and will not therefore be described in detail again.

This embodiment is generally similar to that already described with reference to Figures 1 to 3, but has a different arrangement of leaf springs 14, and their engagement with the seating portion 12.

Thus, there are eight leaf springs 14, which are arranged in two sets of four symmetrically about a central axis of the lifting seat. Thus, each set of four leaf springs is arranged to one side of the central axis, thereby leaving a central gap, whereas, as shown in Figure 3, there is a central leaft spring 14 in the first embodiment. This central gap leaves space in which is mounted a spring-loaded latch, which is described in more detail later.

The (non-disabled) leaf springs 14 exert an upward lifting force on the seating portion 12 via a slider 18a which takes the form of an angle bracket which extends continuously across the width of the seating portion 12, in similar manner to the slider rod 18 shown in Figure 3. Further, in order to ensure proper aligned presentation of each captive nut 24 to a respective fastener 23 (when a leaf spring is to be disabled), a thrust bar 24a is arranged on the underside of the seating portion 12, adjacent to the slider bracket 18a, which presses down onto the leaf springs 14 to hold them substantially flat when the seating portion 12 is moved to the seating position, so that the axes of the nuts 24 are maintained substantially parallel to the axes of the fasteners 23.

This facilitates engagement of the fasteners 23, when required, with the captive nuts 24, in that there would otherwise be a tendency for the leaf springs 14to "uncurl" somewhat when in the lowered position, in the absence of the thrust bar 24a.

As indicated above, a central gap is defined between the two sets of leaf springs 14, and a spring-loaded latch 25 is arranged in this gap. The latch 25 comprises a latch member 26 which is rigidly mounted on a pivotally mounted actuator rod 27, a tension spring 28 which biases the latch member 26 to a latched position, and a stop arm 29 rigid with the actuator rod 27 and engageable with the upper surface of the base portion 11 in order to define the latched position. An operating arm or the like (not shown) is rigidly mounted on one end of the actuator rod 27, and extends along the outer side of one of a pair of opposed side flanges 30 upstanding from a flanged metal frame (not shown in detail) mounted on the base portion 11. This operating arm will be arranged relatively unobtrusively, yet within easy reach and arranged for easy manipulation by a person while sitting on the lifting seat, or by an assistant. An apertured striker 31 is mounted on the underside of the seating portion 12, and is movable to latched engagement with the latch member 24 as the seating portion 12 is moved to the lowered, seating position. The latch member 26 is pivoted against its spring biasing by the striker 31, and then snaps back to retain the seating portion 12 in the lowered position.

Claims

1. A lifting seat comprising a base portion, a seating portion pivotally connected to the base portion for movement between a substantially horizontal seating position and a tilted position, resiliently biasing means arranged to bias the seating portion towards the tilted position, and a releasable latch arrangement for holding the seating portion in the seating position against the action of the biasing means, in which the resilient biasing means comprises a plurality of leaf springs arranged to act between the base portion and the seating portion, and respective disabling means associated with each of at least some of the leaf springs and operable from externally of the lifting seat in order to render the corresponding leaf spring inoperative.

2. A lifting seat according to claim 1, in which each leaf spring is rigidly held at one in cantilever manner on the base portion, and is slidingly engageable at its opposite end with a slider provided on the underside of the seating portion.

3. A lifting seat according to claim 2, in which the slider comprises a transverse member which is engageable simultaneously by all of the operative leaf springs.

4. A lifting seat according to claim 3, in which the transverse member comprises a bar, rod or angle beam which extends continuously across the under side of the seating portion.

5. A lifting seat according to any one of the preceding claims, in which the seating portion is pivotally mounted on the base portion by means of a transverse rod which is carried by a rigid frame secured to the base portion, and a plurality of spaced-apart brackets slidably and pivotally mounted on said transverse rod and secured to the underside of the seating portion.

6. A lifting seat according to claim 5, including one or more torsion springs mounted on said transverse rod and arranged -tO act between the base portion and the seating portion in order to provide a nonadjustable basic minimum lifting force to which can be added, as required, a lifting action of one or more of the leaf springs.

7. A lifting seat according to any one of the preceding claims, including an even number of leaf springs, arranged whereby an equal number of leaf springs is arranged on each side of a central leaf spring.

8. A lifting seat according to any one of claims 1 to 6, including an even number of leaf springs, arranged with an equal number of leaf springs on each side of a central gap.

9. A lifting seat according to claim 8, including a spring-biased latch mounted on the base portion in said central gap.

10. A lifting seat according to any one of the preceding claims, in which the disabling means for each leaf spring comprises a respective threaded fastener which can be taken through the base portion from the underside thereof, and into engagement with a captive nut, or preformed internal thread in the leaf spring.

11. A lifting seat according to claim 10, including a thrust bar mounted on the underside of the seating portion so as to engage the operative leaf springs and to maintain the latter substantially flat when the seating portion is moved to the seating position, whereby alignment isfacilited between a leaf spring to be disabled, and the respective threaded fastener.

12. A lifting seat according to any one of the preceding claims, and adapted to form an integral part of a newly manufactured chair, or to be supplied for application to existing chairs.

13. A lifting seat according to any one of the preceding claims, and incorporated, or adapted for incorporation in a wheelchair.

14. A lifting seat according to claim 13, including a pivotal support arrangement adapted to permit the entire lifting seat to pivot relative to a wheel chair about a substantially vertical axis.

15. A lifting seat according to claim 14, in which the support arrangement comprises a turntable arrangement for permitting pivotal movement of the lifting seat relative to the wheelchair structure, through at least a limited angle.

16. A lifting seat according to any one of the preceding claims, in which the releasable latch arrangement comprises an actuator rod pivotally mounted on the base portion, a latch member rigidly mounted on the actuator rod, an operating arm rigidly secured to one end of the actuator rod, a spring acting between the base portion and the latch member to urge the latter to a latched position, a stop arm mounted rigidly on the actuator rod and engageable with the surface of the base portion to determine the latched position, and an apertured striker mounted on the underside of the seating portion for engagement with the latch member as the seating portion moves to the seating position.

17. A lifting seat according to claim 1 and substantially as hereinbefore described with reference to, and as shown in Figures 1 to 3, or Figure 4 of the accompanying drawings.