BASE STRUCTURE FOR A WHEEL-CHAIR SEAT UNIT

Abstract: Base structure for a wheel-chair seat unit, comprising two mainly parallel sections (1, 1') arranged to support a seat member (2), said sections (1, 1') being pivotably attached in the region of the rear edge portion of the seat member with two extension members (5, 5'), from which two back rest supporting members (10, 10') extend in direction from a seat member (2) attached to the longitudinally extending sections (1, 1'), a locking mechanism (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27) also being arranged, which automatically lock a back rest member (3) in a predetermined operative position in relation to the seat member (2), and which also automatically lock the base structure to a wheel-supporting frame unit when the base structure is placed thereon. When said locking mechanism (14, 15, 16, 17, 18, 19, 20, 21, 23, 24, 25, 26, 27) is manually influenced, it is possible to simultaneously remove the base structure from the wheel-supporting frame unit, and to fold the back rest member (2) to a position adjacent to the seat member. Furthermore, the base structure also includes removably attached arm-rest members, and also removably attached foot and leg supporting members (12, 12'), which by means of separate locking members can be locked to the base structure.

Description: Base structure for a wheel-chair seat unit The present invention relates to a base structure for a wheel-chair seat unit, said seat unit including seat and back rest, with associated leg and foot supporting members, as well as arm rests. For wheel-chairs of demountable type, e.g. as dislosed in Swedish Patent Application No. 7811853-6, there is a need for a suitable base structure for the seat unit which is attached to the wheel- supporting frame, said base structure being arranged to simplify a folding operation of the back rest to a position adjacent to the seat member, and also being arranged to faciliate simple disattachment of associated arm and foot supporting members. When used, the back rest should easily be moved to a predetermined relative position in relation to the seat member, suitable for use, and also be locked in said position. Attachment of arm and foot supporting members should also be accomplished in a fast and simple way. A further requirement is, that the base structure should have a simple bu'ξ, stable design, and that the weight of the base structure should be kept low, in order to faciliate transport of the base structure when same is in a folded together and demounted position. All the above requirements, and also other advantages, are achieved with a base structure according to the present invention. The main and characteristic features of the base structure according to the present invention are disclosed in the following main claim, and further characteristic features are disclosed in related sub- claims. An embodiment of a base structure for a wheel-chair seat unit is more fully described below with reference to the accompanying drawings. Fig. 1 shows an exploded perspective view of an embodiment of a base structure according to the present invention, associated seat and back rest members as well as arm rests not being shown and also without certain associated locking devices. Fig. 2 shows a side view of the base structure shown in fig. 1, assembled and complete. Fig. 3 shows a longitudingal cross-section of a seat supporting U- shaped section, arranged with a locking device utilized for locking the back rest. Fig. 4 shows a view of the side surface of the U-shaped section shown in fig. 3 which is adjacent to the locking device shown in fig. 3, indicating the members included in the locking device arranged to faciliate locking of the base structure against wedge-shaped members extending from the wheel-supporting frame in direction towards the U-shaped sections. Fig. 5 shows a plan view of the base structure with regard to the portions in which the locking device shown in figs. 2 and 3 is located. Fig. 6 shows -a cross-sectional view of an end portion of the base ' structure, having a leg and foot supporting member attached. Fig. 7 shows a perspective view of a forward corner portion of the base structure having a leg and foot supporting member attached, and also showing a locking member for attachment of the leg and foot supporting member to the base structure. Reference numerals 1, V denominate two U-shaped sections, extending in a parallel relationship with the open portion directed towards a lower wheel-supporting frame (not shown). Said sections 1, 1' form together a supporting member for a seat member 2. At the end portions of the sections located in the area where a back rest 3 is intended to be attached, said sections 1, 1' are arranged with a recess 4, 4' in each joining member, thereby forming two end portions having two restricting side surfaces, between which two tubular sections 5, 5' having retangular cross-section are insertable, pivotably attached by means of through bolts or rivets. The U-shaped sections 1, 1' are joined together by means of a tubular distance member 6 at the end portions located opposed to the point of attachment for the tubular sections 5, 5', and two further tubular distance members 7, 7' are arranged to join the U-shaped sections 1, 1' in a mainly parallel relationship, and also facil ate attachment of two double wedge hou- sings 8, 8 1 to each U-shaped section 1, 1'. Said tubular distance members 7, 7' are located adjacently to each other and in a mainly parallel relationship, mainly equally spaced from a centrally located load component extending in direction towards the lower wheel- supporting frame, and which is achieved by the load imposed by a person sitting on the seat member 2. The tubular distance members 7, 7' extend through the U-shaped sections 1, 1' to a contact position against the inside wall surface of each outside wall, and serve as a force absorbing element for the forces transferred to the wedge housings 8, 8 1 in use. The tubular sections 5, 5', pivotably attached to the U-shaped sections 1, 1", have a tubular joining member 9 attached to the outer end portions, and two tubular supporting members 10, 10' for the back rest extending in direction from said tubular members 5, 5', preferably arranged with handles formed at the free end portions, intended to faciliate manual application of force from a person assisting a transport movement of the wheel-chair. A block-shaped guiding member 11, 11' is attached to each section 1, 1', located at the free end portion of said U-shaped sections 1, 1', having a surface parallel in relation to the bottom surface of each section 1, I 1 , which adjacent to the outer end portions of said section 1, 1' is transformed into a surface inclined in relation to said bottom surface, said inclined surfaces being arranged to simplify insertion of a leg and foot supporting member 12, 12' in each section 1, 1'. Since the above description mainly refers to the basic elements of a base structure according to the present invention as shown in fig. 1 it should also be mentioned, that said figure also shows two wedge shaped elements 13, 13', attachable against a wheel-supporting frame, which wedge-shaped elements 13, 13' will be more fully described in a later part of the present description. The base structure according to the present invention also includes a locking mechanism, intended to-serve as a locking member for the back rest 3, and also a locking member for attachment of the base structure against a lower and wheel supporting frame. Said locking members are located at the U-shaped sections 1, 1' between the double wedge housings 8, 8' and the attachment point between the U- shaped sections 1, 1' and the pivotably attached tubular sections 5, 5'. With reference to fig. 3, a first cross-sectional view is shown through said locking device, which view shows the members located adjacent to the outer portions of the U-shaped sections 1, 1', and also the members used for locking the back rest 3 in a predetermined position in relation to the seat member 2. The embodiment shown in fig. 3 comprises of a manually movable lever 14, extending through a slot centrally located in a U-shaped section 1 in a position adjacent to the seat member 2. The lever 14 extends from a locking member 15, pivotably attached to the section 1, arranged to be forced by a spring member 16 to an inclined position in relation to the longditudinally extending direction of the U- shaped section 1 when uninfluenced, and to interlock with a surface adjacent to the bottom surface of the U-shaped section 1 with an internal and adjacent surface to said bottom surface of the pivotably attached tubular section 5, and thus hold said tubular section 5 in. a contact position against the bottom surface of the section 1. As - shown, said interlocking surface of the locking member 5 is preferably arranged inclined in relation to the bottom surface of the U-shaped section 1, in order to secure interlocking and also to faciliate a pivoting movement from said interlocked positon. In case that the lever 14 is influenced in such a way that the locking member 15 is pivotably moved from the interlocking position with the tubular section 5 shown in full lines, said section 5, and associated back rest 3 and supporting members 10, 10' for the back rest 3, can be pivotably moved to the position shown in broken lines, whereby the back rest 3 takes up an adjacent and mainly parallel relationship to the seat member 2. Fig. 3 also shows that the locking member 15 in connection to the portion directed away from the lever 14 also is arranged with a stud 17, which stud extends in direction towards a second part of the locking ecanism as shown in a second cross-sectional view in fig. 4. The second part of the locking mechanism is arranged to faciliate a locking action of the base structure against a wheel supporting frame, from which frame the previously mentioned wedge elements 13, 13', arranged attached to said wheel supporting frame, extend in direction towards the base structure. Adjacent to the free end portions of the wedge shaped elements 13, 13', a stud-shaped locking member 18 is attached to each wedge-shaped element 13, 13', directed towards each other. As shown in fig. 4, said stud-shaped locking members 18 are located in a recess in the adjacent side portion of the U-shaped section 1, when the wedge-shaped elements 13, 13' are inserted into a position surrounded by the double wedge housings 8, 8'. In said inserted position, the wedge-shaped element 13, 13' are held by means of a longitudinally extending locking me eber 19, the end portion of which is adjacent to the stud-shaped member 18 has an interlocking and in relation to the bottom surface of the U-shaped section 1 inclined surface, which is transformed to a second inclined guiding surface 21, intended to move the longitudinally extending locking member 19 when a wedge-shaped element 13, 13' is inserted into associated wedge housing, 8, 8'. Adjacent to the end portion of the locking member 18 directed away from the locking and guiding surfaces, 20 and 21 respectively, a slot 22 is arranged, through which the stud-shaped member 17 attached to the locking member 15 extends. Furthermore, the longitudinally extending locking member 19 is also arranged with a guiding member 23 located adjacent to the slot 22, which together with the longitudinally extending locking member 19 is guided by a tubular axle 24, extending between the U- - shaped sections 1, 1'. A spring member 25 is arranged extending between the end portion of the longitudinally extending locking -member 19 directed away from the locking and guiding surface 20, 21 and an angular attachment means 26, said angular attachment means 26 being attached to adjacently located wedge housing 8 by means of OMPI screws or bolts. In order to prevent that said screws or bolts should prevent a sliding movement of the longitudinally extending member 19, said member is arranged with . a longitudinally extending slot 27. When the lever 14 is influenced, and without regard to the relative position of the back rest 3 in relation to the seat member 2, the base structure can be placed against the wedge-shaped elements 13, 13' attached to the wheel supporting frame. When same are inserted into the wedge housings 8, 8', the stud-shaped locking members 18 at each wedge-shaped element 13, 13' moves adjacently located locking member 19 by contact with associated guiding surface 21 whereafter the spring member 25 faciliates a gliding movement of the locking means 19 in direction towards the wedge shaped elements 13, 13', thereby accomplishing an internally joined and locked position by co-action between the locking surface 20 and the stud-shaped locking member 18, as shown in fig. 4. When it is desired to swing away the back rest 3 from a position adjacent to the seat member 2, the back rest 3 is automatically locked in working position by means of the locking members 15 with- out need for influencing the lever 14, and without regard to whether the base structure is placed on the wheel-supporting frame or not. When the above described mounting operation has been accomplished, the arm rests are inserted, which are arranged with a wedge-shaped member directed towards the double wedge housings 8, 8', insertable into said wedge housing 8, 8', said wedges and co-acting parts of the wedge housings 8, 8' having a mainly trapezoidal cross-section, in order to secure attachment in such a way, that the arm rests are prevented from a pivoting movement in direction outwardly from the seat member 2. As a final operation, the leg and foot supporting members 12, 12', are mounted, having the portions adjacent to the base structure arranged with parts insertable into the U-shaped sections 1, 1', with two parallel surfaces arranged to take up contact against the bottom surfaces of the U-shaped sections . 1, 1' and adjacent surfaces of the block-shaped guiding members 11, 11'. The outer end portion of the insertable parts are preferably arranged with an inclined guiding surface, intended to simplify insertion into a position surrounded by the U-shaped sections 1, 1'. The inserted position is shown in fig. 6. In order to secure attachment of inserted leg and foot supporting members 12, 12' in relation to the base structure, said members 12, 12' are arranged with separate locking means, as shown in fig. 7. Accordingly, each leg and foot supporting member 12, 12', which comprises of tubular sections having preferably square or retangular cross-section, with the free end portion arranged with a foot sup¬ porting plate, arranged with a longitudinally extending locking member 28, having one end portion pivotably attached to the leg and foot supporting member 12, 12', and the other end portion arranged to seize a stud-shaped co-acting member 29, extending from the tubular distance member 6.in an inclined relationship to the seized member 2. Futhermore, a spring member 30 is also arranged at each leg and foot supporting member 12, 12' intended to hold the locking member 28 in an interlocked position with the co-acting stud-shaped member 29. When attaching each leg and foot supporting member 12, 12', asso- ciated locking member 28 is held in such a position that said member 12, 12' completely can be inserted in position into the U-shaped sections 1, V whereafter the locking member 28 is released, whereby the influence from the spring member 30 forces same to take up an interlocked position with the co-acting stud-shaped member 29. Since said co-acting stud shaped member 29 is extending in an inclined relationship to the seat members 2, the leg and foot supporting member 12, 12' are prevented from sliding away from the attached position, unless the locking members are manually moved against the force imposed by the spring member 30 to a position released from the co-acting stud-shaped members 29. When demounting from the above described mounted position, the arm OMPI rests are removed by lifting associated wedge-shaped members in direction upwards from the double wedge housings 8, 8'. The leg and foot supporting members 12, 12' are removed by removing associated locking members 28 to a position released from co-acting stud-shaped members 29, whereafter said members 12, 12' can be withdrawn from the position inserted into the base structure. The lever 14 is thereafter influenced, thereby releasing the base structure from the wedge-shaped elements 13, 13', extending from the lower wheel- supporting frame, simultaneously also releasing the back rest 3, which can be folded to an adjacent and mainly parallel position in relation to the seat member 2. When the lever 14 is influenced, a double function is achieved, firstly the above mentioned folding operation, secondly the removal of the base structure from the wheel-supporting frame. In order to secure best possible attachment and locking properties, the above described locking means are doubled, i.e. located in connection with both U-shaped sections 1, 1 ' . -When the lever 14 is influenced, the locking means on both sides of the seat member 2 are arranged to be influenced, since the movements of the lever 14 is transferred by means of previously described tubular axle 24, whereby the movement of the lever 14 is transferred to the opposed locking means. This is shown in detail in fig. 5. Obviously a manually operable lever can be arranged at only one side of the seat member 2, or on both sides of said member 2, and in the latter case in¬ fluence on desired lever will simoultaneously release the locking means located adjacent to the U-shaped sections, and also faciliate a folding operation of the back rest 3 in direction towards the seat member and/or a lifting movement of the base structure from the wheel-supporting frame. The seat member 2 is preferably pivotably attached at the rear portion against the U-shaped sections 1, 1' having the forward portion arranged with attachment members directed towards the sec- tions 1, 1', arranged with a number of holes separated in longitu¬ dinal direction, which by means of an attachment member, e.g. a screw or bolt with associated nut, can be used for adjustment of different seat angles in relation to the longitudinal direction of the U-shaped section 1, 1'. Also adjustment of the position of the seat member 2 in relation to the surface of the back rest 3 can be accomplished, if the seat member 2 is attached by means of screws extending through slots extending in longitudinal direction in the attachment members. Furthermore, the foot and leg supporting members 12, 12' are preferably arranged as two in relation to each other telescopically joined sections, at least one of said sections having • a number of spaced holes in longitudinal direction of the section arranged to faciliate use of a means extending through the section, which can be attached in desired hole, whereby the length of exten¬ sion for each foot and leg supporting member 12, 12' in direction from the seat member 2 can be decided. The tubular distance member 6, 7, 7' which join the U-shaped sections 1, T, are preferably arranged extending into the sections 1, 1', having each end portion in contact with an internal wall surface of each section 1, 1'. Attachment to this section 1, 1' can be accomp¬ lished by means of screws or bolts, which simplifies, attachment, and also from estethical point of view is preferred, since the tubular distance member 6, 7, 7' do not protrude and are not visable from the outside side surfaces of the U-shaped sections 1, 1'. The stud-shaped member 29, which co-act with the locking member 28 on the foot and leg supporting members 12, 12', are preferably arranged extending mainly perpendicularly in relation to the parts of the foot and leg supporting members 12, 12' extending from the base structure, whereby the locking members 28 preferably interlock with said co-acting stud-shaped member 29, within an angular range between 20 and 70 in relation to the direction of extension for said foot and leg supporting members 12, 12' from the base structure. That the U-shaped section 1, 1' can be used for taking up the rather large forces which are applied against arm rests, back rests 3, and the leg and foot supporting members 12, 12' when used, is based on the fact that the tubular distance members 6, 7, 7' which join the U-shaped sections 1, 1' take up applied side forces, which the rather thin walled U-shaped section 1, V can not take up alone. Accordingly, applied forces against the leg and foot supporting members 12, 12', which result in side forces at the attachment point, are taken up by the forwardly located tubular distance member 6. Side forces applied against the double wedge housings 8, 8' are also taken up by the adjacently located tubular distance members 7, 7', which hold said wedge housings 8, 8'. Also the tubular member 9, which pivotably attach the U-shaped section 1, 1' with the section 5, 5', against which the back rest supporting members 10, 10' are attached, fulfil an important function. Accordingly by using rather thin-walled U-shaped sections 1, 1' as elements supporting the seat, which together with associated tubular distance members 6, 7, 7' faciliate-accomplishing a base structure which fulfils all requirements related to resistance against load on the structure, a base structure is accomplished having a considerably lower weight than previously known types having corresponding comfort and strength. The embodiment shown and described is only intended to serve as an example of an embodiment within the scope of the inventive thought and the following claims, since obviously many modifications can be carried out, while maintaining the characteristic and important features of the present invention. For instance, the locking mechanism can be arranged in a number of ways, while maintaining simultaneous releaseable locking functions for both the back rest 3 in relation to the seat member 2, and attachment of the base structure in relation to the lower wheel supporting frame. Furthermore, included members, denominated U-shaped sections, tubular sections with square or rectangular cross-sections, and in other specific terms, can also be varied considerably, and other means included, e.g. return spring members, can also be varied by utilization of other types of spring members than those shown and described. OMPI

Claims: CLAIMS • 1. Base structure for a wheel-chair seat unit, characterised in that it includes two mainly parallel longitudinally extending sec- tions (1, 1'), arranged to support a seat member (2), said sections (1, V) being pivotably attached in the region of the rear edge portion of the seat member (2) with two extension members (5, 5'), from which two back rest supporting members (10, 10') extend in direction from a seat member (2) attached to the longitudinally extending sections (1, 1'), arranged supporting a back rest member (3) attached to the back rest supporting members (10, 10'), said longitudinally extending sections (1, 1") being joined together by means of a number of longitudinally extending and preferably tubular distance members (6, 7, 7'), which together with the longitudinally extending sections (1, 1') form a base structure, attachable against a wheel-supporting frame unit, a manually releasable locking mechanism (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27) also being arranged, which automatically locks the back rest supporting members (10, 10') in relation to the sections (1, 1') supporting the seat member (2) when the back rest supporting members (10, 10') take up a predetermined angular position in relation to the longitudinally extending sections (1, I 1 ), also locking the base structure as a complete unit when placed against a wheel supporting frame unit, and when influencing said locking mechanism (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27) in order to release same being arranged to faciliate a folding operation of the back rest member (3) to a position adjacent to the seat member (2), and also to release the base structure as a complete unit from a wheel-supporting frame unit. 2. Base structure according to claim 1, characterised in that the locking mecanism includes a locking member (15) which can interlock with the end portions of the extension members (5, 5') adjacent to the longitudinally extending sections (1, 1'), when the extension members (5, 5') with a pivoting movement moves the back rest member (3) in a position separated from the seat member (2) and being arranged to be influenced by a spring member (16) and to interlock - - with at least one of the extension members (5, 5') when same take up a predetermined relative position in relation to the longitudinally extending sections (1, 1'). 3. Base structure according to any of claims 1 and 2, characterised in that the locking mechanism (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27) includes a locking member (19), arranged to interlock with at least one member (13, 13') extending from the wheel-supporting frame unit in direction towards the base structure when the base structure is placed on the wheel-supporting frame unit by means of influence from a spring member (25) co-acting with the locking member (19). 4. Base structure according to any of claims 1 - 3, characterised in that the locking mechanism (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27) comprises of two mainly similar mechanisms, arranged adjacent to each longitudinally extending section (1, 1'), internally connected by means of an axle (24) extending between the mechanisms, arranged to cause a corresponding influence of a second " mechanism similtaneously as a fist mechansim is influenced. 5. Base structure according to any of claims 1 - 4, characterised in that the locking mechanism (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27) includes a manually operable member ( " 14) "for releasing the locking mechanism from a locked position, and when using two mechanisms arranged at each longitudinally extending section (1, 1'), at least one of said mechanisms being arranged with said member (14). 6. Base structure according to any of claims 1 - 5, characterised in that a wedge housing ((, 8') is attached to each longitudinally extending section, extending mainly perpendicularly in relation to the longitudinal direction of the sections (1, 1'), arranged to ' faciliate insertion into each wedge housing (8, 8') of a wedge shaped member (13, 13'), extending in direction away from a wheel- supporting frame unit. 7. Base structure according claim 6, characterised in that the wedge-shaped elements (13, 13') attachable to the wedge housings (8, 8'),. are arranged with locking means (18, 18'), co-acting with the locking mechanism (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27). 8. Base structure according to claim 6, characterised in that the wedge housings (8, 8') are arranged as double wedge housings, one wedge housing being arranged to faciliate removable attachment of an arm rest member, having a wedge-shaped member co-acting with each wedge housing (8, 8'). 9. Base structure according to any of claims 1 - 8, characterised in that the end portions of the longitudinally extending sections (lj I 1 ), directed away from the pivotably attached extension members (5, 5'), are arranged to faciliate insertion of two foot and leg supporting members (12, 12') into a position mainly surrounded by the sections (1 , 1 ') . , 10. Base structure according to claim 9, characterised in that the foot and leg supporting members (12, 12'), attachable against the longitudinally extending sections (1, 1'), are arranged with pivotably attached longitudinally extending locking members (28) at a distance from the attachment point, when said foot and leg supporting member ( . 1 . 2, 12') being inserted into a position surrounded by the longitu¬ dinally extending sections (1, 1'), being arranged to faciliate a pivoting movement to an interlocking position with a preferably individual co-acting locking means (29) for each foot and leg suppor¬ ting member (12, 12"), extending from a member (6) joining the longitudinally extending sections (1, 1') and having a angle mainly perpendicular in relation to the direction of extension for the foot and leg supporting members (12, 12') in relation to the longitudi- . nally extending sections (1, 1'). OMPI ~ AΠVΓ\

Inventors: BERGMAN P
Applicants: BERGMAN P
Application year: 1981
Main classification: A61G5
IPC codes: A61G5