EP0960614A2

EP0960614A2 - Fittings and chair for use with such fittings

Info

Publication number: EP0960614A2
Application number: EP99110351A
Authority: EP
Inventors: Jens Kugle
Original assignee: Kugle AS; Kugle Holding AS
Current assignee: Kugle Holding AS
Priority date: 1998-05-28
Filing date: 1999-05-28
Publication date: 1999-12-01
Also published as: DK75298A; DK174580B3; DK174580B1; DK200100230A; EP0960614A3

Abstract

There is described a chair (1) comprising a back (2), an arm rest (3), and a seat (4). The back (2) and the arm rest (3) are swinging relative to the seat as well as the arm rest also is swinging relative to the back. In order to establish a swinging of the back (4) which is neutral and ergonomically correct with a connected swinging of the arm rest, the back (4) is arranged so that it swings according to a course where it extends as a tangent to a curve. The curve is approximately circular and has a centre defined via a journal (19) and which is in a position before the back cushion (5) and above the seat cushion (6). Furthermore, the arm rests (3) are supported by a bracket (25) connected with the back (2) and which is guided in a groove (21), so that it performs approximately half the circle relative to the swinging of the back (2).

Description

The present invention concerns to a fitting for use in a chair, preferably wheel chair, comprising a seat, a back, and arm rest, each comprising a frame and a cushion, and where the back and the arm rests are pivotable relative to the seat. The invention likewise concerns such a chair comprising a seat, a back, and arm rest, each comprising a frame and a cushion, and where the back and the arm rests are pivotable relative to the seat.
In such chairs it is important that the different chair parts, such as arm rest, arm rest support, forehead rests, foot rests and the like, can be adjusted quickly and simply in order to accommodate different parts of the chair for individual sizes and possibly also deformities on the persons using the chair.
A chair of this kind where back and arm rests can be pivoted and/or regulated relative to the seat are particularly used for wheel chairs for the disabled. However, a chair according to the invention may also find application within other chairs, as for example swivel chairs, car seats, and the like.
Until now there has not existed fittings that have been simple to make and easy to place for mutual mounting and regulating the different parts of the chair. Prior art brackets had thus to be adjusted individually to different parts in the chair which has hampered a uniform manufacturing procedure. Furthermore, the prior art fittings have hindered an easy and ready adjustment of the different parts of the chair.
It is also important that the different elements of the chair in the form of back, seat, and arm rest may be swung in an anatomically correct way. This is necessary in particular when speaking of wheel chairs for disabled or physically handicapped persons. In the following, focus will therefore be on explaining the requirements for the function of the chair for supporting the understanding of the significance of the need of a fitting being simple to produce and easy to operate.
Usually a back is adjusted relative to the seat by pivoting the back about a turning point fastened to a frame situated under the chair seat. Such a pivoting is undesirable for anatomical reasons as an elongation of the location of the back relative to the seat takes place. This is especially a drawback for disabled or physically handicapped persons, where a wheel chair has to be arranged for fulfilling several requirements. In such a wheel chair there is thus a need for having the back of the person correctly positioned in relation to padding and the like, for example because of deformities in the back. In order to get relief from a normal upright sitting position, there is also a need for the user to swing the back simultaneously with a neutral position has been established, so that the user can maintain his or her back in a correct position against the back irrespective of the angle of pivot. This is also important out consideration to the user which has auxiliary equipment in the form of controls mounted on the back frame and which are operated by the user's head. Thus it is important that control rods operated with forehead or mouth are correctly positioned in relation to the user. For other users, fixing of the head to the back occurs. In this situation it is also important that there may be established a swinging where the upper part of the body of the user is in a neutral position relative to the back so that the head fixing is not unnecessarily loosened or tightened on the user. The prior art chairs do not make allowance for these requirements. When the back is pivoted relative to the seat, a neutral pivoting is not achieved where the back follows the natural swinging of the user's upper body part relative to the seat. This gives rise to incorrect support of the back of the user with consequent risk of discomfort or definite damages on the user.
Furthermore, the occurring elongation of the back relative to the seat will imply that the clothes of the users will be pulled apart. This gives discomfort to the user. Such a discomfort will be experienced in swivel chairs or the like irrespectively whether the chair has a back adjusted individually to the back of the user.
A wheel chair normally has an control panel disposed foremost on one of the arm rests. It is important that the user has an easy and unhindered operation of the control buttons independent of the swinging of the back. The prior art wheel chairs are disadvantageous as the arm rest is not pivoted simultaneously with the back or pivoted in a fixed angle together with the back. In a first situation where the arm rest is fastened to the frame of the seat of the chair, even a relatively limited pivoting of the back will cause that the user may loose contact with the control panel. In second case, where the arm rest is fastened to the frame of the back and pivots together with the back, the arm rest would come to stand obliquely upwards with an angle corresponding to the tilt of the back. In practice, this is not an ergonomical correct position for the user. Chairs arranged to keep the arm rest horizontal simultaneously with moving the arm rest backwards during the tilting of back are also known. This construction makes it possible for the user to have an almost unhindered access to the control buttons on the control panel. However, keeping the arm rest in a horizontal position is not ergonomically correct either.
Thus there is also a need for providing an arm rest following the back in an ergonomically correct way and in a way that the user is continuously capable of having a correct support on the arm rest, as well as it will also be possible for the user to operate control buttons on the control panel of the arm rest.
An ergonomical correct swinging of back and arm rest relative to the seat is important, irrespectively whether there is spoken of wheel chairs for disabled persons, persons with deformities or of common chairs, as, for example, swivel chairs.
In wheel chairs or other special chairs in which persons have to go in and out, as for example car seats, chairs in clinics, and the like, where persons have to have easy access to and from the chair simultaneously with the possibility of swinging the back relative to the normal upright position of the user, it is also important that the arm rest is shaped in such a way that easy access to and from the chair is created and also that there is created possibility for possible helpers to get a physically handicapped wheel chair user up and down of a wheel chair in an easy way.
In known chair constructions of the kind mentioned in the introduction, there is not indicated a simple solution to an arm rest construction, which in a simple way may be swung to a position under the seat or behind the back, thereby creating an easy access to the chair.
It is the purpose of the present invention to indicate a solution meeting the above requirements and which makes it possible to make a technically simple fitting which in an easy way may connect individual parts in the chair and which makes it easy to regulate these parts for adjustment to individual users, and at the same time to indicate a chair wherein the fitting is used and which remedies the drawbacks by the prior art chairs by making possible an ergonomically correct swinging of the back and the arm rest relative to the seat, and which at the same time is arranged for easy adjustment of arm rests to correct position in relation to the user, as well as the construction shall make possible an easy swinging of the arm rest to a position forming easy access to and from the chair.
This is achieved according to the present invention with a fitting of the kind mentioned in the introduction, which is peculiar in that it comprises two side plates provided with a groove for receiving a part of the frame elements of the chair, preferably the sides of flatly oval tubes, a tubular middle piece having a stub or the like for fastening a sub-element and which is arranged for being positioned on a conical peg or in a conical boring, respectively, which is fastened to one of the side plates, the middle piece having a conical boring or a conical peg, respectively, so that clamping of the side plates of the fitting about the frame element via the conical faces establishes a rotationally firm position for the middle piece and the sub-element connected thereby.
The chair according to the invention is peculiar in that it comprises tubes, preferably flatly oval tubes, in the frames for arm rests, seat and back and the bracket of the arm rest, and that for mutual fastening of the sub-elements of the chair there is used a fitting comprising two side plates with a groove for receiving the tubes and a middle piece which is situated rotatably above a conical peg on one of the side plates, and which by clamping the side plates about the tube is fixed in a rotationally firm position, the middle piece comprising a stub or the like for fastening sub-elements to the chair.
In a special embodiment, the chair is peculiar in that the back is arranged for swinging along a course where the back extends as a tangent to a curve being approximately circular and having a centre located in a position before the cushion of the back and above the cushion of the seat, and that the arm rests are arranged for approximately pivoting half the angle of the pivoting of the back.
The fitting according to the invention may be used for mutual connection of the different frame elements in the chair as well as it may be used for fastening other auxiliary equipment or other elements forming a part of a chair. The fitting is easy to manufacture as it consists of few single elements, and it will be simple to place the fitting with the two grooves about a frame element in the chair and thereafter perform a clamping. Because of the conical form, it will be possible to establish a rotationally firm position for the middle piece. It is thus possible to fix a second frame element or an auxiliary equipment in relation to a first frame element received in the two grooves in the side plates of the fitting. The fitting may, for example, be provided with a journal used for controlling the pivoting of an arm rest as described later. The journal engages a guideway and it utilized for controlling the pivoting of the arm rest. Because of the placing of the groove in the side plates, it will be relatively easy to perform an individual adjustment of the height of the arm rest by performing a displacement of the fitting along the length of the bracket of the arm rest and to perform a clamping of the two side plates about the bracket in a suitable position. With this fitting, the journal for use in the guideway will be welded to the middle piece, and the two side plates are ten squeezed about a flatly oval tube which is bent for forming the bracket of the arm rest.
A fitting of this kind is also usable for mounting the arm rest to the bracket. By placing a flatly oval tube received in the grooves of the side plates under the arm rest pad, there is achieved an angular displacement and longitudinal displacement in a simple way. By loosening the two side plates, the arm rest may thus be displaced longitudinally of the groove, and simultaneously there may be established a swinging of the two side plates in relation to the middle piece. After clamping the fitting, there is established a rotationally firm position of the arm rest relative to the bracket.
A corresponding fitting may be used on other frame elements in the chair, for example the frame of the back, for fixing different auxiliary equipment, such as head control, reading lights, and like, on the frame of the wheel chair.
Surprisingly, with the chair according to the invention is has appeared that with different test persons there is achieved an ergonomically correct positioning of the person relative to the back during its swinging. Surprisingly, it has thus appeared that a chair having the back situated as a tangent to a curved course during the swinging, do not create any elongation, but instead form a neutral swinging where the upper part of the user's body is in a largely fixed position in relation to the back.
By tests it appeared that the movements of the back during the reclining acted as a tangent to a curved course, and that this curved course with approximation was a circle. In order to achieve the best possible accommodation to different persons, it has appeared with approximation, that the centre of the swinging of the back is placed between 40 and 200 mm above the seat and before the back and preferably at a distance of about 100 mm.
It was surprising that the back would perform a swinging movement with a position as a tangent to a curved course, as all commonly known back movements in wheel chairs, car seats and the like, until now have been moved as a radian with a centre of rotation preferably being situated in a position under the back and behind the seat of the chair.
It will be possible to establish the swinging movement of the back relative to the seat according to different constructional principles. Each of these constructional principles can be varied in different ways in order to adjust the course of the curve to a form giving the best ergonomical swinging of the back of the chair.
A first principle is to let the back be guided in a curved groove fastened to the seat frame or the chair frame. Such a guiding in a groove can take place by letting two pins engage the groove and control the movements of the back, as the swinging movement of the chair is established by using a linear actuator disposed under the chair seat. This may be said to be a guideway arrangement. Alternatively, the guideway arrangement may also be established by a single pin engaging a guideway at one side of the seat or at each side of the seat, and that a second point of the frame of the back is fixed to the actuator under the seat of the chair.
According to a second principle, the back may be mounted for swinging about a point being centre of the curved movement. Here, also, the back will be moved by a linear actuator under the chair seat. Even if this construction is possible, it will yet be disadvantageous as a frame arrangement situated at each side of the seat in a position above the seat and before the back is required. This may make alighting from and entering the chair difficult
A third possibility is the use of a link arrangement. With a link arrangement there may be created a curved movement with the back following the tangent to the curved course by placing a double link system under the back. A chair built up according to this principle can be peculiar in that the link arrangement between the seat and the back comprises a central actuator acting on a first arm which is fastened to an axle being provided with a second arm at each end, the second arm engaging a third arm at each side of the back via a journal, which third arms being pivotably suspended on each their brackets mounted at each side of the seat frame.
During the swinging of the back it has surprisingly appeared that the ergonomically correct swinging of the arm rest is not a swinging through the same angle and not a keeping of the arm rest in a horizontal position either. It has appeared, that a swinging of the arm rest under the half angle relative to the swinging of the back gives an ergonomically correct positioning of the arm rest relative to the back when this is swung back. It is to be noted that a back in a chair according to the invention would be able to swing from a largely vertical position through 90° to a largely horizontal position. However, a back will yet preferably be swung 60° from a vertical position. By such a swinging, the arm rest will perform a corresponding upward directed swinging through about 30° from a horizontal position. The swinging of the arm rest may occur according to the same principle as the swinging of the back. However, it is preferred to use a guideway arrangement in combination with a rotational suspension of the arm rest on the back frame. The arm rest is thus swung by providing a curved groove in the guideway arrangement and letting a journal interact with this groove. The journal is fastened to a bracket supporting the arm rest. The bracket supporting the arm rest is preferably a U-shaped bracket, which at its first free end is pivotably suspended to the back and which at its second free end supports the cushion of the arm rest. The movement of the arm rest is suitably controlled by letting the groove in the guideway comprise a mainly cardioid groove.
The previously mentioned journal used for controlling the swinging of the arm rest is arranged for being pulled out of engagement with the groove. This may take place by providing a resilient pin on the fitting which is fastened to the bracket of the arm rest. By pulling the pin out of engagement with the groove, the arm rest can be swung to a position behind the back or under the back in order to facilitate entering and alighting from the chair. By fastening the pin by means of fittings arranged to be displaced along the bracket, it is possible to allow a vertical adjustment of the arm rest by placing the pin in the desired initial position in the groove which ensures a correct height of the arm rest above the seat in relation to a user.
The invention will hereafter be explained more closely with reference to the accompanying drawing, where

Fig. 1: shows a partially schematic view for illustration of chair seat, back, and arm rest for a chair according to the invention, with the back placed in an upright, largely vertical position,
Fig. 2: shows a view corresponding to Fig. 1 with the back and the arm rest in a reclined position,
Fig. 3: shows a schematic view illustrating the principle of the swinging of the back,
Fig. 4: shows a partial view illustrating two initial positions for an arm rest in a chair according to the invention,
Fig. 5: shows a view illustrating the swinging of the arm rest simultaneously with the reclining of the back,
Fig. 6: shows a perspective view illustrating a first embodiment of a fitting according to the invention,
Figs. 7 and 8: show views corresponding to Figs. 1 and 2, but with different elements left out of the drawing for better illustration of the connection between the back and the seat, and
Figs. 9 and 10: show two further embodiments of the fitting according to the invention.

In Fig. 1 there is shown a partial view of a chair 1 according to the invention. The chair 1 is shown with the back 2 of the chair in an upright, largely vertical position and with the arm rest 3 of the chair in a largely horizontal position at a distance above the seat 4 of the chair. The chair has a back cushion 5, an arm rest cushion 6', and a seat cushion 6. The cushions are mounted on a back frame 7, an arm rest frame 8, and a seat frame 9, respectively. The back 2 is arranged to be swung relative to the seat 4. The swinging is effected by means of a liner actuator 10 mounted in a bracket 11 which is fastened in a central position on the seat frame 9. The actuator operates a link arrangement 12 for enacting the rearward swinging of the back 2. The link arrangement 12 comprises a first arm 13 which is rotatably suspended to a piston in the actuator 10. The arm 13 is firmly connected to a spindle 14 extending toward both sides of the seat. At each end of the spindle 14 there is provided a second arm 15. At its end, the arm 15 is provided with a journal 16 engaging a groove 17 in a third arm constituted by a bracket plate 18 at each side of the back 2. A third arm or the bracket plate 18 is pivotably suspended via the journal 19 which is mounted on bracket plates 20 at each side of the seat frame 9. The middle axis of the journals 19 will thus form a centre for the swinging of the back 2.
The journal 19 will be placed so that the middle axis is approximately 100 mm before the back and above the seat measured from the person's points of abutment on back and seat when the cushions 5,6 are compressed. This distance of approximately 100 mm corresponds to an adult person. When speaking of a child, this distance to back and seat will be less.
The bracket plates 20 are provided with a groove 21 used for controlling the swinging of the arm rest 3. The frame of the arm rest 3 comprises a flatly oval tube 22 on which the arm rest cushion 6' is mounted. Via a fitting 23 according to the invention, the tube 22 is mounted at one end 24 of a U-shaped bracket 25. At its other end, the bracket 25 is pivotably suspended about a journal 26 mounted on the back. The arm rest is thus pivotably suspended relative to the back 2 and is simultaneously pivotable in relation to the seat 4. The fitting will be explained more closely with reference to Fig. 6.
At an intermediate position on the bracket 25, there is mounted a fitting 23' provided with a journal 27 interacting with the groove 21 in the bracket 20. By rearward swinging of the back 2, the arm rest will swing upward, but this will occur under half the angle of the swinging of the back, as the groove 21 is a largely cardioid shaped groove. These mutual relationships appear more clearly from Fig. 5.
When the back is swung rearwards and the arm rest performs a partial swinging upward, the arm of the user will stay on the cushion 6' of the arm rest, and the user may easily and unencumbered activate a control panel fastened on the arm rest, and turning angles being uncomfortable or unergonomical in the user's elbow, hand, or shoulder, will not occur.
In Fig. 2 is seen the chair of Fig. 1 in a position, where the back 2 is swung about 60° rearwards in relation to its initial vertical position. At the same time, the arm rest is swung through about 30°. It is seen, that the journal 27 by the swinging of the back has passed through the groove 21 and is now situated at the lowermost part of the groove 21 in the bracket 20. From Fig. 2 is also seen, that the actuator 10 which is placed centrally under the chair seat has is piston placed in an extended position, whereby the first link arm 13 has rotated the spindle 14 and thereby pivoted the second link arm 15 forwards. During the forward directed pivoting of the link arm 15, the journal 16 would be displaced in the groove 17. The groove 17 thus has a length causing that the journal 16 is in the shown extreme position, when the chair is completely upright and in its position being swung 60° backwards, which in the shown embodiment is the maximum reclining of the back 2 of the chair. In an intermediate position, the journal 16 will be placed at the other end of the groove 17. The groove 17 thus makes possible the swinging of the back 2 about the journals 19 in such a way that the back 2 continuously extends as a tangent to a circle with centre in the centre of the journal 19. The journal 27 is a resilient pin, which may be pulled out of engagement with the groove 21. This makes possible the swinging of the arm rest about the journal 27, so that the arm rest 3 may be swung to a position behind the back 2 or down under the seat 4 with the purpose of facilitating entering and alighting from the chair 1.
In Figs. 7 and 8 views corresponding to Figs. 1 and 2 are shown of the chair 1. In Figs. 7 and 8, the arm rest 3, the bracket 25, and the mounting thereof are omitted, as well as the back cushion 5 is also omitted. Hereby a more clear link arrangement 12 is seen, which establishes the connection between the back 2 and the seat 4. As we are speaking of identical elements, no specific explanation will be given to Figs. 7 and 8.
In Fig. 3, 28 indicates a line for the person's point of abutment or face of abutment on the seat when the cushion of the seat is compressed because of the weight of the person. 29 indicates in a similar way a plane for the person's abutment point or abutment face on the back, when the back cushion is compressed because of the weight of the person. 30 indicates a centre of a circle, which is a tangential curve for the positions of the back during the swinging. 31 indicates the distance of the position of the centre 30 above face 28. 32 indicates the distance from the centre 30 to the face 29 of abutment of the back. The distances 31,32 will usually be between 40 and 200 mm, but will preferably be about 100 mm for an adult person. In Fig. 3 there is illustrated a vertical position where it is seen that the face 29 extends as a tangent to the circle 33. Thereafter is shown a position for the laying down of the back through 30°, where the plane of the back 29', 29'' and 29''' is still tangent to the circular arc 33. It is noted that in practice a back will be arranged for a reclining through about 60°. A lowering of the back to horizontal position will only occur in rare cases.
Fig. 4 shows an arm rest 3 in two different positions above the seat. The height adjustment of the arm rest 3 above the seat 4 thus takes place by loosening the fitting 23' and displacing it along the bracket 25 until the arm rest has a desired initial height above the seat 4. When the arm rest has the desired height, the fitting 23 is loosened and the arm rest is given an approximately horizontal position, whereafter the fitting 23 is fastened again.
In Fig. 5 the arm rest 3 is seen in an initial position with an approximately vertical orientation and in a position where it is swung through 30° corresponding to a reclining of the back through 60°. It is seen, that the journal 27 during the swinging of the arm rest is displaced from a position in the upper part of the groove 21 to a position in the bottom of the groove by the rearward directed swinging of the back through 60°. In the inserted circle in the top of Fig. 5, the connection between the swingings are illustrated in order to illustrate the cardioid curve 34 corresponding to the shape of the groove 21. The first end 35 of the cardioid curve correspond to the initial position of the journal 27 with the arm rest situated horizontally, and the second end 36 of the cardioid groove correspond to the position of the journal 27 in the other extreme position with the arm rest swung through 30° and the back swung through 60°.
Fig. 6 shows a first embodiment of the previously mentioned fitting 23 (and 23'). The assembling fitting 23 comprises a first side plate 37 and a second side plate 38. Each of the side plates are provided with a groove 39 that may receive the sides of the flatly oval tubes used for making the frames of the chair. The second side plate is firmly connected with a conical peg 40. A middle piece 41 having a conical boring 42 is intended for placing over the conical peg 40 and serves as a distance piece, which is adjusted to the width of the flatly oval tubes, so that clamping of the fitting 23 by means of a screw 44 screwed into a thread 43 in the peg 40 ensures that the fitting is fixed on the flatly oval tube. At the same time, the middle piece is fixed in a rotationally firm position by the engagement of the conical faces.
The middle piece 41 is provided with a bracket 48 welded onto it. This may, for example, be intended for a spring biased journal used for controlling the movements of the arm rest. The middle piece 41 can also be provided with a stub whereby it is mounted or welded at the first end 24 of the bracket 25. Hereby the middle piece 41 may serve to fasten the arm rest 3. When the fitting 23 is used in connection with the bracket 25, the grooves 39 will be curved with a curvature corresponding to the curvature in the bottom of the U-shaped bracket 25.
The fitting 23 may easily be loosened and may at the same time be given a longitudinal displacement by displacing the fitting along a tube in the groove 39 and simultaneously performing a corresponding adjustment of the rotational position of the middle piece 41 in relation to the side plates 37,38. Thus the fitting may be used in a simple way for mutual fastening of sub-elements in the chair.
The fitting 50 shown in Fig. 8 has some parts in common with the fitting 23. These are designated with the same reference symbols.
The fitting 50 differs by having grooves 39', which extend arc-shaped. This fitting 50 is thus suitable for being fastened about an arc-shaped tube piece, for example an arm rest bracket 25.
Fig. 9 illustrates a further embodiment of a fitting 50. This is provided with a middle piece 41' which at each end has a conical peg 45. The conical peg 45 is intended for engaging conical holes 46 provided in each of the side plates 37,38. By clamping together the side plates 38,39 of the fitting, there is thus established a rotationally firm engagement with the engagement of the pegs 45 in the borings 46.
In Fig. 10 there is illustrated a fitting 60. This fitting has straight grooves 39 in the side plates 37,38. The fitting 60 is, like the fitting 50, clamped together by means of two screwbolts 44. In the fitting 60 the middle piece is omitted. However, here there may be provided a middle piece corresponding to the middle piece 41' illustrated in Fig. 8. The fitting in Fig. 10 comprises an elongated rod 47. The rod 47 serves as alternative fastening of sub-elements instead of fastening to a middle piece. This may be advantageous when sub-elements are to be fastened and which are difficult to place in immediate connection to a frame member or a bracket fastened between the two side plates 37,38. Thus the rod 47 may be used when one has to fasten elements, as for example forehead rests or the like, to the upper part of a chair back.
In the above, the invention has been specifically described in connection with back 2, arm rest 3, and seat 4. These elements may find application in different kinds of chairs where it is desired to achieve a neutral swinging of back and an ergonomically correct swinging of the arm rest simultaneously with the swinging of the back. Such chain may, for example, be utilized in wheel chairs, in commercial vehicles, in dental or medical clinics.

Claims

A fitting for use in a chair comprising a seat; a back, and an arm rest, each comprising a frame and a cushion, and where the back and the arm rests are pivotable relative to the seat, characterised in that it comprises two side plates provided with a groove for receiving a part of the frame elements of the chair, preferably the sides of flatly oval tubes, a tubular middle piece having a stub or the like for fastening a sub-element and which is arranged for being positioned on a conical peg or in a conical boring, respectively, which is fastened to one of the side plates, the middle piece having a conical boring or a conical peg, respectively, so that clamping of the side plates of the fitting about the frame element via the conical faces establishes a rotationally firm position for the middle piece and the sub-element connected thereby.
A chair for use together with a fitting according to claim 1, characterised in that it comprises tubes, preferably flatly oval tubes, in the frames for arm rests, seat and back and the bracket of the arm rest, and that for mutual fastening of the sub-elements of the chair there is used a fitting comprising two side plates with a groove for receiving the tubes and a middle piece which is situated rotatably above a conical peg on one of the side plates, and which by clamping the side plates about the tube is fixed in a rotationally firm position, the middle piece comprising a stub or the like for fastening sub-elements to the chair.
A chair according to claim 2, characterised in that the back is arranged for pivoting along a course where the back moves as a tangent to a curve being approximately circular and having a centre located in a position before the cushion of the back and above the cushion of the seat, and that the arm rests are arranged for approximately pivoting half the angle of the pivoting of the back.
A chair, preferably wheel chair, comprising a seat, a back, and arm rests, each comprising a frame and a cushion, and where the back and the arm rests are pivotable relative to the seat; characterised in that the back is arranged for swinging along a course where the back extends as a tangent to a curve being approximately circular and having a centre located in a position before the cushion of the back and above the cushion of the seat, and that the arm rests are arranged for approximately pivoting half the angle of the pivoting of the back.
A chair according to claim 3 or 4, characterised in that the back is connected with the seat via a link arrangement or a guideway arrangement, and that the arm rest comprises a U-shaped bracket which at one end is pivotably suspended to the back, and which at its other free end supports the cushion of the arm rest, and which is controlled via a guideway arrangement between the seat frame and the bottom of the bracket.
A chair according to claim 4 or 5, characterised in that the guideway arrangement comprises a plate with a curved groove interacting with a rotational pin which may engage the groove and which is arranged for being displaced through the groove by pivoting the back and/or the arm rest.
A chair according to claim 4 or 6, characterised in that the rotational pin for controlling the swinging of the arm rest is arranged to be pulled out of engagement with the groove in order to allow the swinging of the arm rest to a position behind the back and is arranged displaceable along the bracket in order to allow a vertical adjustment of the arm rest.
A chair according to any of the claims 2 - 7, characterised in that the guideway arrangement for controlling the swinging of the arm rest comprises a mainly cardiod shaped groove.
A chair according to any of the claims 2-8, characterised in that the centre of journal of the back is situated between 40 and 200 mm, preferably about 100 mm, before and above the point of the person's abutment on the back and the seat when the cushions are compressed.
A chair according to any of the claims 2-9, characterised in that the link arrangement between the seat and the back comprises a central actuator acting on a first arm which is fastened to an axle being provided with a second arm at each end, the second arm engaging a third arm at each side of the back via a journal, which third arms being pivotably suspended on each their bracket mounted at each side of the frame of the seat.