GB2274242A - Adjustable chair-bed for medical use. - Google Patents

Abstract

An adjustable chair-bed (1) for use in supporting a patient during medical treatment comprises a rest portion (3) defining a supporting surface (44) upon which the patient rests in use. An adjustment means (2) connects the rest portion to a base (8) to allow adjustment of the vertical position of the rest portion for raising or lowering the patient. The adjustment means comprises a linkage (20, 23) having a parallelogram type configuration and a hydraulic ram (34). <IMAGE>

Description

"ADJUSTABLE CHAIR BED" This invention relates to an adjustable chair-bed for use in supporting a patient during medical treatment.

It is known to provide adjustable chair-beds which allow a patient to be supported in a sitting, supine or intermediate position for medical treatment. Such chair-beds typically are wheeled to allow transport of the patient in any desired position.

It is also known from US-4858260 to provide adjustment means for providing height adjustment such that the patient can be raised or lowered. Typically such adjustment is effected using a vertically extensible linear actuator. A disadvantage of such actuators is that, if the actuator comprises a simple hydraulic ram, the ram cannot be contracted to less than one half of its fully extended length so that the available range of vertical adjustment is limited.

According to the present invention there is disclosed an adjustable chair-bed for use in supporting a patient during medical treatment comprising a rest portion defining a supporting surface upon which a patient rests in use, a base supporting the rest portion, and adjustment means operatively connecting the rest portion to the base and operable to adjust the vertical position of the rest portion whereby the patient may be raised or lowered in use, wherein the adjustment means comprises a linkage pivotally connected to the base and to the rest portion respectively and an actuator operable to effect angular displacement of the linkage between raised and lowered angular positions corresponding to raised and lowered vertical positions of the rest portion respectively.

An enhanced range of vertical adjustment is thereby attainable in comparison with prior art arrangements. A further advantage is that the linear actuator in accordance with the present invention tends to experience loading only in a direction which is coaxial with its direction of extension whereas in prior art arrangements having a vertically extending actuator the actuator must typically be sufficiently heavily engineered to sustain bending and twisting moments.

Preferably the linkage is co-operable with the rest portion and the base to provide a parallel motion mechanism in which the attitude of the rest portion relative to the base is constrained to be invariant in response to operation of the adjusting means.

It is then not necessary to provide any additional means for maintaining the rest portion horizontal.

Preferably the parallel motion mechanism is characterised by pivotal movement of the linkage about horizontal axes defining the apices of a parallelogram when viewed in axial projection, the parallelogram having opposite vertical sides which remain vertical throughout operational movement of the adjusting means and are respectively defined by upper and lower first pivotal axes associaed with the base and by upper and lower second pivotal axes associated with the rest portion.

Conveniently the linkage comprises a first link pivotally connected to the base and to the rest portion about the upper first pivotal axis and the upper second pivotal axis respectively and a second link pivotally connected to the base and to the rest portion about the lower first pivotal axis and the lower second pivotal axis respectively.

Conveniently each of the first and second links comprises a pair of arms rigidly interconnected by an obliquely extending brace.

Such an arrangement, which may be regarded as a double wishbone configuration, is inherently rigid.

The linkage may be pivotally connected about longitudinally extending axes such that angular displacement of the linkage is accompanied by transverse movement of the rest portion relative to the base.

The term longitudinal is here used to denote the head to foot orientation of the chair-bed having regard to the normal supine position of the patient and the transverse direction is used to denote the left/right direction.

Conveniently the linkage is operatively connected between an upwardly extending pillar of the base and a downwardly extending support leg of the rest portion.

Preferably the actuator comprises a linear actuator connected between the base and the rest portion so as to extend obliquely relative to the vertical direction.

Preferably the linear actuator has a first end pivotally connected to the base at a lower end portion of the support leg and a second end connected to the rest portion at a lower end portion of the support leg.

Conveniently the linear actuator comprises a hydraulic ram.

The terms "vertical" and "horizontal" are used throughout the specification to denote the normal orientation of the components of the chair-bed when it rests in its normal orientation on a horizontal supporting surface.

A preferred embodiment of the present invention will now be disclosed by way of example only and with reference to the accompanying drawings of which: Figure 1 is a plan view of a chair-bed in which the rest portion is omitted for clarity; Figure 2 is a front end elevation of the chair-bed of Figure 1; Figure 3 is a front end elevation of the chair-bed of Figures 1 and 2 in a fully raised position; Figure 4 is a left side elevation of the chair-bed of Figures 1, 2 and 3 in the fully raised position; Figure 5 is a perspective view of the chair-bed of preceding Figures with the rest portion being shown; Figure 6 is a perspective view of the chair-bed of Figure 5 in a partially reclined position; and Figure 7 is a perspective partial rear view of the chair-bed of preceding Figures showing detail of the adjustment means.

In Figure 1 a chair-bed 1 is partially shown in plan view to reveal an adjustment means 2. The complete chair-bed 1 is shown in Figures 5 and 6 to additionally include a rest portion 3 consisting of a seat 4, leg-rest 5, foot-rest 6 and back-rest 7.

The chair-bed 1 comprising a wheeled chassis 8 having wheels 9 and supporting a sub-frame 10 via the adjustment means 2 such that the sub-frame 10 can be raised and lowered. The seat 4 of Figures 5 and 6 is secured to mounting brackets 11, 12 and 13 of the sub-frame 10.

The chassis 8 is rigidly formed of aluminium tubing in a generally H-shaped configuration as viewed in plan view in Figure 1 to support at its lateral extremities the four wheels 9 and having a longitudinally extending member 14 to which a vertically projecting pillar 15 is rigidly secured.

The pillar 15 is rectangular in horizontal cross-section and tapers slightly with increasing height, the pillar having rear and forward end faces 16 and 17 respectively. Upper and lower first pivot pins 18 and 19 respectively extend horizontally in vertically spaced relationship through the pillar 15 each projecting both rearwardly and forwardly from the end faces 16 and 17 respectively. A first link 20 is pivotally connected to the upper first pivot pin 18, the first link comprising rear and front arms 21 and 22 respectively which engage the upper first pivot pin 18 adjacent the forward and rear end faces 16 and 17 respectively.

A second link 23 extends parallel to the first link 20 and spaced vertically beneath the first link, the second link being pivotally connected to the lower first pivot pin 19 and having rear and front arms 24 and 25 respectively connected to the pivot pin adjacent the forward and rear end faces 16 and 17 respectively.

The rear and front arms 21 and 22 of the first link 20 are rigidly braced together by means of a diagonally extending brace 26 and the second link 23 is similarly provided with a brace 27.

The first and second links 20 and 23 have respective first and second free end portions 28 and 29 which are pivotally connected to upper and lower second pivot pins 30 and 31 respectively as shown in Figure 2. The upper and lower second pivot pins 30 and 31 are horizontally journalled in a vertically extending support leg 32 so as to be vertically spaced from one another by a separation equal to the vertical spacing between the upper and lower first pivot pins 18 and 19.

The pivot pins 18, 19, 30 and 31 are therefore arranged at the apices of a parallelogram when viewed in longitudinal projection as in Figure 2 and pivotal movement about the first pivot pins 18 and 19 results in vertical displacement of the support leg 32 whilst retaining the support leg in parallel vertical orientation with the pillar 15.

The first and second links 20 and 23 together comprise a linkage which extends generally transversely with respect to the chair-bed and, as seen in plan view in Figure 1, the longitudinally extending member 14 of the chassis 8 is offset towards the left-hand side of the chassis to accommodate the extent to which the linkage projects towards the right-hand side of a chair-bed 1.

The sub-frame 10 consists of an assembly of vertical metal plates rigidly mounted on an upper end surface 33 of the support leg 32 so as to provide a horizontal support for the seat 4.

A simple hydraulic ram 34 comprises a cylinder 35 and an extending piston arm 36 which are respectively connected to the chassis 8 and the support leg 32. The cylinder 35 is pivotally connected to a chassis mounted pivot pin 37 at a location vertically spaced below the lower first pivot pin 19. The piston arm 36 is pivotally connected to the lower second pivot pin 31 at a location intermediate the rear and front arms 24 and 25 of the second link 23, the support leg 32 having a lower end portion 38 which is recessed to reveal a middle portion 39 of the lower second pivot pin 31 to which the piston arm 36 is connected.

The hydraulic ram 34 is supplied with hydraulic fluid via flexible piping (not shown) from a pump 45 which is foot actuated by means of an actuator 40 as shown in Figure 5. Actuator 40 has a pumping pedal 41 by mean of which the hydraulic ram 34 can be extended by pumping using conventional hydraulic pump action and a release pedal 42 which when depressed will actuate a valve to allow the release of hydraulic pressure to allow the ram 34 to contract.

The back-rest 7, leg-rest 5 and foot-rest 6 are interconnected by a further linkage (not shown) which provides for the back-rest, leg-rest and foot-rest to be articulated relative to the seat 4 in synchronisation with one another such that conversion between a supine patient position in Figure 5 and seated patient position of Figure 7 can be smoothly effected by single actuation of a handle 43.

The seat 4, leg-rest 5, foot-rest 6 and back-rest 7 together define a supporting surface 44 for supporting a patient which can be adjusted through a wide range of heights. Figure 2 shows the sub-frame 10 in its fully lowered position in which the first and second links 20 and 23 extend downwardly at an angle of approximately 360 below the horizontal from the upper and lower first pivot pins 18 and 19 respectively. Figure 3 shows the sub-frame 10 in a fully raised position in which the first and second links 20 and 23 extend upwardly at an angle of approximately 370 above the horizontal from the first upper and lower first pivot pins 18 and 19.

During height adjusting movement the sub-frame 10 and hence the supporting surface 44 is maintained parallel to the chassis 8 so as to remain horizontal when the chair-bed is on a horizontal supporting surface, this parallel motion mechanism being provided by the parallelogram type arrangement of links 20 and 23 in combination with the pillar 15 and support leg 32.

As can be seen from Figures 2 and 3, the pivot pins 18, 19, 30 and 31 define pivotal axes which when viewed in axial projection form the apices of a parallelogram. One vertical side of the parallelogram is defined by pivot pins 18 and 19 and a second vertical side by pins 30 and 31, the vertical orientation of the sides being maintained throughout pivotal motion of the linkage and thereby ensuring that the support leg 32 remains parallel to the pillar 15 and thereby is maintained in a vertical orientation.

As will be apparent from Figure 3, vertical adjustment is accompanied by some degree of horizontal movement of the sub-frame 10 and hence of the supporting surface 44 due to pivotal motion of the links in a plane extending transversely of the chair-bed 1. Since however the vertical movement is effected gradually this horizontal movement is insufficient to be disconcerting to the patient.

In an alternative arrangement, the linkage may be reconfigured by turning through 900 such that the pivotal axes extend laterally. The associated horizontal movement then occurs longitudinally instead of laterally.

Claims (10)

CLAIMS:

1. An adjustable chair-bed for use in supporting a patient during medical treatment comprising a rest portion defining a supporting surface upon which a patient rests in use, a base supporting the rest portion, and adjustment means operatively connecting the rest portion to the base and operable to adjust the vertical position of the rest portion whereby the patient may be raised or lowered in use, wherein the adjustment means comprises a linkage pivotally connected to the base and to the rest portion respectively and an actuator operable to effect angular displacement of the linkage between raised and lowered angular positions corresponding to raised and lowered vertical positions of the rest portion respectively.

2. A chair-bed as claimed in claim 1 wherein the linkage is co-operable with the rest portion and the base to provide a parallel motion mechanism in which the attitude of the rest portion relative to the base is constrained to be invariant in response to operation of the adjusting means.

3. A chair-bed as claimed in claim 2 wherein the parallel motion mechanism is characterised by pivotal movement of the linkage about horizontal axes defining the apices of a parallelogram when viewed in axial projection, the parallelogram having opposite vertical sides which remain vertical throughout operational movement of the adjusting means and are respectively defined by upper and lower first pivotal axes associaed with the base and by upper and lower second pivotal axes associated with the rest portion.

4. A chair-bed as claimed in claim 3 wherein the linkage comprises a first link pivotally connected to the base and to the rest portion about the upper first pivotal axis and the upper second pivotal axis respectively and a second link pivotally connected to the base and to the rest portion about the lower first pivotal axis and the lower second pivotal axis respectively.

5. A chair-bed as claimed in claim 4 wherein each of the first and second links comprises a pair of arms rigidly interconnected by an obliquely extending brace.

6. A chair-bed as claimed in any preceding claim wherein the linkage is pivotally connected about longitudinally extending axes such that angular displacement of the linkage is accompanied by transverse movement of the rest portion relative to the base.

7. A chair-bed as claimed in any preceding claim wherein the linkage is operatively connected between an upwardly extending pillar of the base and a downwardly extending support leg of the rest portion.

8. A chair-bed as claimed in any preceding claim wherein the actuator comprises a linear actuator connected between the base and the rest portion so as to extend obliquely relative to the vertical direction.

9. A chair-bed as claimed in claim 8 as dependent on claim 7 wherein the linear actuator has a first end pivotally connected to the base at a lower end portion of the support leg and a second end connected to the rest portion at a lower end portion of the support leg.

10. A chair-bed as claimed in any of claims 8 and 9 wherein the linear actuator comprises a hydraulic ram.