Invalid Chairs

Abstract

The invention is concerned with invalid chairs for facilitating standing up and sitting down operations by invalids who are normally unable to stand up and sit down without difficulty. The invalid chair of the present invention comprises a chair base, a seat portion, a back rest, linkage interconnecting the chair base, seat portion and back rest, and resilient means to urge the seat portion and back rest to raised positions and thereby assist an occupant in rising from a sitting position, the back rest being connected to the chair base by a quadrilateral linkage including upper and lower links extending forward from the lower part of the back rest to pivots on the chair base, the seat portion being pivoted to the back rest or to the upper link in the vicinity of the junction therebetween and further linkage being provided whereby as the seat portion and back rest are raised by the resilient means, the seat portion pivots to an angular position where its forward end lies upwardly with respect to the upper link and the inclination between the seat portion and backrest is greater than the corresponding inclination with the seat fully forward.

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation in part of our application Ser. No. 203699, Filed Dec. 1st, 1971, entitled "INVALID CHAIRS," now abandoned.

Description

BACKGROUND

This invention relates to Invalid Chairs and is an improvement in the invalid chair disclosed in Austin G. Morse-Brown U.S. Pat. No. 3679260 issued July 25, 1972 and assigned to the Assignee of this invention.

According to the invention disclosed in the said patent there is provided an invalid chair comprising a seat portion connected to a chair base by guide means which guide the seat portion such that it moves between a lowered sitting position and a raised position in which latter position it lies forward, wholely above and tilted forward relatively to the lower sitting position, and resilient means to urge the seat portion towards the raised portion. As disclosed in further detail in the said patent, a practical embodiment of this linkage takes the form of a pair of arms extending forward and downward from the seat portion to pivot on forward extensions of the chair base. Due to these extensions, the overall size of the chair is large and there can be a tendency for an invalid entering or leaving the chair to trip over an extension.

Further invalid chairs are known from R. G. Heyle U.S. Pat. No. 3,138,402 issued June 23, 1964 and G. A. Hodge U.S. Pat. No. 3,640,566 issued Feb. 8, 1972 in which a seat portion is elevated by resilient means in order to facilitate the rising of an occupant from the chair. The Hodge and Heyle Patents both disclose mechanisms incorporating quadrilateral linkages for guiding the seat portion to its raised position and by that means they obviate the requirement for a large forward extension of the chair such as disclosed in the said Morse-Brown Patent. However, the chair disclosed in the Heyle Patent incorporates a seat portion and back rest which both move together with a rear link of the quadrilateral linkage with the result that the movement of the chair is primarily a lifting movement with only a very limited degree of forward tilting. Without an appropriate degree of forward tilting, the occupant of the chair cannot effectively be raised to a near upright standing position. The chair of the Hodge Patent obviates this problem by causing the seat portion of the chair to move with an upper link of the quadrilateral linkage and causing the back rest to move with the rear link of the quadrilateral linkage. Whilst obviating the disadvantage of Heyle, the Hodge chair introduces the further disadvantage that the seat portion cannot be raised up to a substantial extent as it is being tilted and thus again it does not fully effectively help to raise an occupant to a standing position.

SUMMARY

A primary object of the present invention is to provide an invalid chair having a linkage which enables it to avoid the disadvantages of the prior art chairs.

According to the present invention there is provided an invalid chair comprising a chair base, a seat portion, a back rest, linkage interconnecting the chair base, seat portion and back rest to raised positions and thereby assist an occupant in rising from a sitting position, the back rest being connected to the chair base by a quadrilateral linkage including upper and lower links extending forward from the lower part of the back rest to pivots on the chair base, the seat portion being pivoted to the back rest or to the upper link in the vicinity of the junction therebetween and further linkage being provided whereby as the seat portion and back rest are raised by the resilient means, the seat portion pivots to an angular position where its forward end lies upwardly with respect to the upper link and the inclination between the seat portion and back rest is greater than the corresponding inclination with the seat fully lowered.

BRIEF DESCRIPTION OF THE DRAWINGS

Three embodiments of the invention will now be described by way of example with reference to the accompanying drawings. In the drawings:

FIG. 1 is a side elevation of a chair with the seat portion in its lowered position;

FIG. 2 is a view corresponding to FIG. 1, but with the seat portion in a raised position;

FIG. 3 is a view corresponding to FIG. 1 of a second embodiment;

FIG. 4 is a view corresponding to FIG. 2 for the Second embodiment;

FIG. 5 is a sectional side elevation on line B--B of FIG. 7 of the operating mechanism of a chair according to the invention, showing the chair itself in chain dotted outline;

FIG. 6 is a view corresponding to FIG. 5 but showing the back rest and seat portion in their raised positions as opposed to their lowered positions, and;

FIG. 7 is a plan view of the linkage in the configuration shown in FIG. 5 in the direction of arrow A of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference should be made to both FIGS. 1 and 2, but most of the individual components can be more clearly seen from FIG. 2 due to the fact that they are more spaced apart in the raised position of the chair.

A chair base comprises a flat rectangular frame 11 having two square section steel side members 11a, cross members 11b and 11c, upwardly projecting rear support 12 at the rear corners, and upwardly projecting forward supports 13 at the front corners. The supports 12 and 13 are pillars near the corners of the frame 11 for co-operating with two identical linkages formed from steel tubes and bars, one at each side of the chair. Only one such linkage will be described in detail in view of the identity between the two linkages.

An upper, generally rearwardly extending link 14 is pivoted to the forward projection 13 near the top thereof at 15. A lower generally rearwardly extending link 16 extends substantially parallel to the link 14 at a position spaced below the link 14. The forward end of the link 16 is pivoted at 17 to a small bracket 18 on the support 13 so that the pivot point 17 lies behind the pivot point 15. At their rear ends, the two links 14 are joined by a rear link 19 to which they are pivoted at 20 and 21 respectively. The rear link 19 is substantially vertical in the lowered position of the chair as shown in FIG. 1, but the geometry of the quadrilateral linkage formed by links 14, 16 and 19 and the fixed link constituted by an imaginery line on the frame joining points 15 and 17 is such that the link 19 undergoes a small degree of rotation in an anti-clockwise direction as shown in the drawings as it is raised from the lowered position shown in FIG. 1 to the raised position shown in FIG. 2.

A seat portion 23 which may be a padded substantially flat platform, with a steel frame is pivoted at 20 and engages the link 19 through a bracket 24 and an adjusting screw 25. The screw 25 provides an adjustable lost motion connection between the link 19 and the seat portion as will be described below. After this lost motion has been taken up, the screw 25 engages the link 19 and then the seat portion 23 and the link 19 are coupled together so that they move and rotate in unison. Thus, as the link 19 tilts during raising movement the seat portion 23 also raises and tilts simultaneously. There is also an associated forward movement of the link 19 and of the seat portion 23. The angle of the seat portion 23 in its raised position may be adjusted to suit various invalids by adjustment of the screw 25 which varies the angle between the seat portion 23 and the rear links 19.

The seat is also provided with a back rest 26 which, as shown in FIG. 1, has an adjustable upper portion 27 which may be itself or may incorporate a detachable head rest. The back rest is formed as a continuation of the link 19 so that it also pivots and moves with the link 19. However, during initial tilting movement from the lowered position shown in FIG. 1, the seat portion tilts at a faster rate than does the back rest due to the lost motion associated with the screw 25. Thus, in the raised position the back rest is still near vertical when the seat portion is fully tilted. This position of the back rest has the advantage of enabling a patient to lean against the back rest whilst in the process of sitting down, but without having to bend forward to conform to an excessively tilted back rest.

The upper link 14 has a downward and forward extension 28 which is connected to a tension spring 29 which extends between the lower end of the extension 28 and a fixture 31 on the frame.

The lower ends of the two downward extensions are in practice joined by a cross member which carries several springs such as 29 between the cross members and the fixture 31, which in such a case extends across the chair between the two side members 11a.

The operation of the chair is substantially in accordance with the operation of the chair disclosed in the said co-pending application and for this reason it is considered that a detailed explanation is not necessary. In brief, with the seat portion 23 in its raised position, an invalid leans against and partially lowers himself through a short distance into the seat, the springs 29 having been adjusted to hold the chair in its raised position, despite part of the weight of the patient being supported by the chair. The patient then leans back, which increases the load on the seat portion and causes the seat to be lowered gently against the effort of the springs 29. Because the seat lifts up relatively high and comes well forward as well as tilting, the patient can initially lean back against the chair without having to lower himself substantially, similarly the combined lowered, tilting and moving back of the seat portion can be carried out with the patient's feet on the ground and without substantial bending of the knees. As in the said co-pending application, suitable means should preferably be provided for locking the seat portion in the lowered position, so that the patient once seated can move freely without fear of ejection from the chair. When a patient desires to rise from the chair, the locking mechanism is released while the patient leans back and thereafter the patient leans forward to decrease the load on the seat portion so that the effort of the spring or springs 29 raises the seat portion and the patient to the raised position shown in FIG. 2. In this position, the patient is near to a standing position and can then complete the standing motion himself without difficulty.

In this way, a patient who is capable of walking but not capable of sitting into or standing up from a conventional chair without assistance becomes more independent of assistance.

The chair shown in FIGS. 3 and 4 corresponds in many respects to the chair shown in FIGS. 1 and 2 where suitable similar reference numerals have been used, but with the prefix "1." One primary distinction is that the irregular quadrilateral linkage has been replaced in FIGS. 3 and 4 by a parallelogram linkage having upper and lower links 114 and 116 and a rear link 119. Substantially midway along these longitudinal links 114 and 116 there is a further link 51 parallel to the link 119 and having an upward and forward extension 52 carrying a roller 53. The roller 53 engages with the underside of the seat portion 123. In use, as the chair is tilted from the position shown in FIG. 3 towards the position shown in FIG. 4, the roller 53 swings in an arc and in turn tends to swing the seat portion 123 away from the upper link 114 so that the degree of tilting of the seat portion 123 is less than the corresponding degree of tilt of the link 114. As in previous embodiment, the back rest 126 is coupled to the rear link 119 and remains substantially upright.

The embodiment shown in FIGS. 3 and 4 also incorporates a leg rest as disclosed in the said Morse-Brown Patent. The leg rest 57 is connected at a pivot 54 to a forward and downward extension of the seat portion 123 in order to support the rear part of the leg rest near the forward edge of the seat portion. A link 55 joins the leg rest near the forward part thereof to the forward extension 128 of the upper link 114. In this way, as can be seen by a comparison, between FIGS. 3 and 4, the leg rest moves from a substantially vertical position under the forward edge of the seat portion when the seat portion is raised to a leg supporting position in front of the seat portion when the seat portion is lowered. The leg rest of FIGS. 3 and 4 could be incorporated in the chair of FIGS. 1 and 2.

Reference should now be made to FIGS. 5 through 7 in which a third and preferred embodiment is described.

The chair of FIGS. 5 to 7 comprises a chair base 111 constituted by two upholstered side portions forming arms of the chair and joined together at the front and rear edges thereof by further framework and upholstered panels, (not shown). The chair base may be of any conventional furniture construction such as a timber frame covered with padding and upholstery material or with hardboard or similar material covered in any upholstery material. The chair base is supported on two forward castors 101 and two rear-fixed feet 102 to enable the chair to be moved easily when tilted on its castors, but to prevent inadvertent movement.

The chair also comprises a seat portion 112 and a back rest 113 and both the seat portion 112 and back rest 113 may similarly be constructed using normal furniture techniques. The seat portion 112 requires a rigid lower rear edge and rigid lower side edges for mounting purposes and similarly the back rest 113 requires rigid side portions near its lower edge for mounting purposes. The type of construction should cater for these requirements.

The seat portion 112 and back rest 113 are mounted in the chair base 111 by means of a linkage and this linkage itself is mounted on a sub-frame comprised by two side plates 114 which in use are bolted or otherwise secured in the chair base. The side plates 114 are generally L-shaped and at their forward upper edge incorporate pivots 115 for the forward end of an upper link 116. The side plates also incorporate two pivots 117 below and slightly to the rear of the pivots 115 and these pivots 117 support the forward end of a lower link 118. At their rear ends, the upper and lower links 116 and 118 carry rear links 119 connected thereto by pivots 21 and 22 respectively. The links 116, 118 and 119 together with the portion of the side plates between the pivots 115 and 117 together form a quadrilateral linkage. The upper link is formed from two longitudinal square section steel tubes joined together near their rear ends by a square section tube 123. The lower link 118 is formed from two longitudinal steel strips joined together near their rear ends by a square section steel tube. The rear link 119 is formed from two individual steel plates.

The forward end of the link 116 incorporates two downward extensions 125 which are joined by an angle section cross member 126. A similar angle cross member 127 is connected to the cross member 124 of the lower link by means of long bolts 128 and corresponding nuts 129 so that the position of the angle member 127 with respect to the cross member 124 is adjustable. A series of tension springs 131 are connected between the angle member 126 and the angle member 127. The number of springs which are used is variable in that some of the fifteen springs shown in FIG. 7 can be removed if desired. Similarly, the tension of these springs is adjustable by means of the bolts 128. These springs exert a tilting movement on the upper link tending to pivot it in an upward direction with respect to the forward pivot 115 and thereby tend to pivot the whole quadrilateral linkage towards the position shown in FIG. 6. In this position, the rear link 119 contacts the cross member 123 and acts as a stop against further movement.

The rear link 119 carries the back rest 113 by means of a pair of arms 132 which are pivotted to the pivot 121 and are angularly adjustable through a small angle with respect to the link 119 by virtue of quadrants 133 incorporating a series of bolt holes 134 by means of which the arms 132 may be secured at a series of angular positions to the link 119. The angular adjustment is provided to enable the chair to be adjusted for different occupants or different users.

The seat portion 112 is pivotted to the cross member 123 by means of hinges 135. Thus, in the absence of further linkage, the seat portion 112 would rest on and rise with the upper link 116 to the near vertical position shown in FIG. 6. However, this degree of tilting is undesirable because it would tend to result in an occupant of the chair being tilted forward rather than lifted up and for this reason additional linkage in the form of bell crank levers 136 is provided. Two bell crank levers 136 are pivotted at 137 to the upper link substantially mid-way along its length. The forward ends of the bell crank levers 136 carry rollers 137 which engage with the undersurface of the seat portion 112. The rear and downwardly extending parts of the bell crank levers 136 engage with rollers 139 secured to fixed pivots 140 on the lower links 118.

Thus, as the linkage, seat portion and back rest rise from the lowered position under the influence of the springs, the back rest tilts forward slightly from a normal angled position to a substantially upright position. This angular movement takes place because the pivot 117 is behind the pivot 115 and the link 118 is shorter than the link 116. Also, the movement of the links 116 and 118 tilts the bell crank 136 with respect to these links so that rollers 138 tilt the seat portion 112 with respect to the links 116 in a direction towards the seat back 113. It should be observed that in the raised position shown in FIG. 6, the actual inclination of the seat portion is between the inclination it would have if it moved with the link 116 and the inclination it would have it if moved with the seat back 113 at a fixed inclination thereto. This intermediate inclination overcomes the disadvantages associated with both extreme inclinations, namely that the occupant is respectively either pushed forward with insufficient lift or is lifted up with insufficient forward tilting to bring the occupant to a standing position.

In order to hold the seat portion and back rest in their lowermost position against the pressure of the springs 131, a latch member 142 is provided on a transverse rod 143 which extends between the two side plates 114. The latch member 142 co-operates with a pin 141 which is mounted on the transverse member 124 of the lower link as best seen in FIG. 7. The latch member 142 is operable to release the pin 141 by means of a rod 144 extending up towards the forward edge of the arm portions of the chair base 111 to a push button 146. A spring 145 tends to hold the latch member in its engaged position. The rod 144, spring 145 and push button 146 may be duplicated on both sides of the chair.

Claims

We claim:

1. An invalid chair comprising:

a chair base;

a seat portion;

a back rest;

linkage operatively interconnecting the chair base, seat portion and back rest;

resilient means operatively connected between one end of said linkage and said base to urge the seat portion and back rest to raised positions and thereby assist an occupant in rising from a sitting position;

said linkage comprising a quadrilateral linkage operatively connecting the back rest to the chair base, said quadrilateral linkage including upper and lower links extending forward from the lower part of the back rest, said links having forward ends pivotally connected to the chair base, and rear ends pivotally connected to the back rest;

the seat portion being pivoted to one of said back rest and said upper link, in the vicinity of the junction therebetween; and

a bell crank lever pivoted to said upper link intermediate the ends thereof, having one arm engaged with the underside of the seat portion and the other arm operatively connected to said lower link whereby movement of said quadrilateral linkage causes rotation of the lower arm whereby the upper arm also moves and lifts said seat portion with respect to said upper link.

2. An invalid chair according to claim 1, said quadrilateral linkage being a parallelogram linkage and said other arm of said bell crank lever being pivoted to said lower link.

3. An invalid chair according to claim 1, said other arm of said bell crank lever engaging a roller mounted on said lower link.

4. An invalid chair according to claim 1, further comprising adjustment means for said back rest whereby the angular position thereof with the chair in its lowered position may be varied to suit the occupant.

5. An invalid chair comprising:

a chair base;

a seat portion;

a back rest;

linkage operatively interconnecting the chair base, seat portion and back rest;

resilient means operatively connected between one end of said linkage and said base to urge the seat portion and back rest to raised positions and thereby assist an occupant in rising from a sitting position;

said linkage comprising a quadrilateral linkage operatively connecting the back rest to the chair base, said quadrilateral linkage including upper and lower links extending forward from the lower part of the back rest, said links having forward ends pivotally connected to the chair base, and rear ends pivotally connected to the back rest;

the seat portion being pivoted to one of said back rest and said upper link, in the vicinity of the junction therebetween; and

cooperating abutments on a lower portion of said back rest and on said seat portion, said abutments being adapted to engage each other during motion of the seat portion and back rest, said abutments being spaced apart in the lowered position of the seat portion and back rest whereby on initial lifting movement of the seat portion and back rest, the seat portion tilts with respect to the back rest; and on further upward lifting motion, the seat portion is fixed in its angular relationship to the back rest.

6. An invalid chair according to claim 5, said lower link being shorter than said upper link whereby said back rest tilts forward as it is raised.