A CHAIR

Abstract: A seat comprising a base mount (1) which supports an adjustable backrest (2) and a seat cushion (3) whose rear part is pivotally supported by the backrest (2) and whose forward part has a supportive part (31, 33; 12) which is displaceably carried by the base mount (1), wherein the arrangement is such that the bottom part of the backrest (2) and the seat cushion (3) are moved forwards relative to the base mount (1) as the backrest (2) is inclined rearwardly from an upright position. The backrest (2) has firmly connected thereto a frame structure (4) which extends in beneath the seat cushion (3); in that the frame structure (4) is displaceably carried by a support (5', 5"; 5, 6, 8, 9) mounted on the base mount (1) and has a guide (10) which coacts with the support (5', 5"; 5) and which in the upright position of the backrest (2) extends generally rearwards and upwards; and in that a supporting arrangement (23, 6, 7, 8, 13) connected to the base mount (1) supports the front supporting part (31, 33; 12) of the seat cushion (3) for movement along a predetermined movement path (23) and in that the guide (10) and the movement path (23) have extensions such that the height of the front edge of the seat cushion (3) above the floor will be held generally constant or will decrease as the backrest (2) is swung from its upright position to a rearwardly inclined position.

Description: A Cha±r The present invention relates to a seat construction of the kind defined in the preamble of Claim 1 (see for instance EP-A-0,248,418, Figures 12-14). A seat construction of the kind in which the lower part of the backrest and the seat cushion are pushed forwards as the backrest is inclined rearwardly from an upright position is, among other things, desirable in collective passenger transport vehicles, such as buses, coaches and railway carriages, for instance, so that when inclined rearwardly, the backrest will not encroach unduly on the space intended for the person seated immediately there- behind with his/her backrest raised to an upright posi¬ tion. An object of the present invention is to provide a novel, advantageous seat of the aforesaid kind with which the aforesaid desired movement pattern can be achieved with the aid of simple, inexpensive devices which take-up only little space and which afford stable connection between the seat base-mount, the seat back¬ rest and the seat cushion. This object is achieved with a seat constructed in accordance with the following Claim 1. Further developments of the seat are defined in the depending Claims. The invention enables the devices required for adjusting the position of the seat to be given a very simple, constructive form and to be placed beneath the seat cushion in a manner which will have minimum encroachment on the seating space. The inventive seat may be of the kind which includes a base mount which carries an ad¬ justable backrest, a seat cushion whose rear part is pivotally supported by the backrest and whose forward part has a supporting part which is dispiaceably carried by the base mount, wherein the arrangement is such that the bottom part of the backrest and the seat cushion are moved forwards in relation to the base mount as the backrest is moved rearwardly from an upright position (EP-A-0,248,418, Figures 12-14), and against this back- ground the seat is characterized in that the backrest has firmly connected thereto a frame structure which extends in beneath the seat cushion; in that the frame structure is movably supported by a support means on the base mount; in that the frame structure has guide means which coact with the support means and which extend essentially obliquely rearwards and upwards in the upright position of the backrest; in that the forward support part of the seat cushion carries a support means which is connected to the base mount and intended for movement along a predetermined path; and in that the extensions of the guide and the movement path are such that the height or elevation of the front edge of the seat cushion is maintained essentially constant or decreases as the backrest is swung from an upright position to a rearwardly inclined position. According to one embodiment of the inventive seat, the support means and the support part coacting with said support means are comprised of a guide curve and a runner. The guide curve is preferably mounted on the base mount and the support part has the form of a runner which is mounted on the underside of the seat cushion and which runs along the guide curve as the backrest is inclined rearwardly. According to another embodiment of the inventive seat, the support part is formed by an abutment surface on the seat cushion. This abutment surface is carried by a first end-part of at least one arm which is pivotally carried by the base mount at its other end-part. The support means engages a carrier surface on said first end-part of the arm, and the support surface and the abutment surface are in constant abutment with one another along a limited region whose position depends on the pivotal position of the arm. The support is formed by virtue of the fact that the frame structure is sup¬ ported in its forward region by the aforesaid arm and is pivotally connected to said arm at a point located between the two end-parts thereof. The support is also formed by virtue of the fact that the rear part of the frame structure has at least one abutment surface which forms the aforesaid rail rests movably against a sup¬ portive projection carried by the base mount. In this regard, the arm may have a forwardly angled first end- part which includes a generally upwardly facing convex support surface which coacts with a preferably flat abutment surface. The convex support surface may be located forwardly of the connecting point between the frame structure and the arm, wherein the radius of curvature of the support surface decreases in a rearward direction. Further characteristic features of the invention and advantages afforded thereby will be apparent from the depending Claims and also from the following description of an exemplifying embodiment of the invention made with reference to the accompanying drawings. Figure 1 illustrates partially and highly schematically a first exemplifying embodiment of an inventive seat, with the seat backrest shown in its raised position. Figure 2 illustrates the seat of Figure 1 with the backrest inclined rearwardly. Figures 3 and 4 illustrate a second exemplifying embodi- ment of an inventive seat corresponding to the Figure 1 and 2 illustrations. The seat illustrated in Figures 1 and 2 includes a base mount 1, a backrest 2 and a seat cushion 3. The term seat cushion will be understood to include the horizon¬ tal seating surface of a seat. The base mount 1 is comprised of a horizontal, rectangular box beam 100 which carries a base-mount element 101. The element 101, and therewith the seat, can be moved transversely along the beam 100. The backrest 2 includes a frame structure 4 which is angled forwardly from the general direction of the backrest and extends in beneath the seat cushion 3. Provided in the rear end-part of the seat cushion 3 is a downwardly extending arm 32 whose lower end is pivotally connected to the frame structure 4 by means of a pivot shaft 11. The frame structure 4 carries a guide 10, preferably in the form of a guide rail, on each side of the frame structure 4. These guide rails 10 extend between two pairs of rollers or runners 5', 5", which are mutually spaced apart horizontally on the base-mount element 101, so as to stably receive the frame structure 4 and there¬ with the backrest 2. The backrest is inclined by dis- placement of the rails 10 through the pair of rollers. Each roller pair 5', 5" comprises two rollers 52, 53 which are arranged to run on the upper side and the bottom side of respective guide rails 10. The roller pair 5' is carried by a generally vertical linkage arm 51 which is pivotally connected to the base-mount ele¬ ment 101 by the shaft of the bottom roller 53. The roller pair 5" is similarly carried by a generally vertical linkage arm 51, wherein the shaft of the upper roller 52 forms a pivot journal for the arm 51 on the base-mount element 101. The upper ends of the two link- age arms 51 are biassed towards one another by means of a pull spring 54. This arrangement of pivotable linkage arms 51 and the spring load acting thereon provides play-free abutment of the two rollers 52 in each roller pair with the rail 10, while the illustrated journals of the arms 51 cause the frame structure 4 to rest stably on the base mount, at least when the backrest 1 is subjected to force in its rearwardly inclined direction. Mounted on the upper part of the element 101 is a roller track 23. Mounted on the underside of the forward region of the seat cushion 3 is a support arm 31 which carries a support runner 33 which runs on the track 23. Mounted on the underside of the rear part of the seat cushion 3 is a support arm 32 whose bottom end is pivotally con- nected to the frame structure 4 by means of a pivot shaft 11. The arm 32 has considerable length and the seat cushion 3 will therefore be moved forwards in a favourable manner as the backrest 2 is swung backwards. The arm 31 carrying the runner 33 forms the forward support part of the seat cushion 3. The rails 10 and the track 23 are slightly concave in an upward direction and are configured so that the height or vertical elevation of the front edge of the seat cushion will be held essentially constant or will decrease as the backr. sv is swung from its upright position to a rearwardly inc ; -.ned position. The guide 10 of the illustrated embodiment has a curva- ture such that the region of its centre of curvature will be located generally above the base mount 1 and also above the seat cushion 3, for instance immediately above half the length extension of the seat cushion 3, when the backrest 2 is inclined forwardly to a maximum, wherein said centre region lies, for instance, at a height above the seat cushion 3 which corresponds to the length of the seat cushion. Although not shown in detail in the drawings, the mecha¬ nism which functions to move the seat to its inclined position may conventionally be assisted by air springs when adjusting the seat from a rearwardly inclined position to an upright position. Furthermore, means may be provided for locking the seat in any chosen position between the two end positions illustrated in Figures l and 2. Movable stop means may also be provided for adjusting the effective length of the guide 10 or the effective length of the track 23, and therewith adjust the limit positions for the backrest and seat cushion in the upright and rearwardly inclined positions of the seat. When adjusting the seat from the upright position shown in Figure 1 to the rearwardly inclined position shown in Figure 2, which can be effected by pressing backwards against the upper region of the backrest 2, the bottom region of the backrest is moved forwards relative to the base mount 1, possibly against the action of a spring device (not shown) when such a device is fitted, which facilitates later forward inclination of the seat. As the backrest is inclined rearwardly, the guide 10 moves forwards in relation to the roller pairs 5', 5" and the runner 33 runs down along the track 23, since the seat cushion 3 is also moved forwards as a result of its connection with the frame structure 4 at the pivot connection 11. As the frame structure 4 moves forwards, the rear part of the seat cushion 3 is lowered while, at the same time, the forward end of the seat cushion 3 is lowered in a controlled fashion in accor- dance with the shape of the rail 10 and the curve 23. The rail 10 can be assumed to have a circular shape, in which case the point E will lie in a vertical plane centrally between the roll pairs 5', 5" at a height above said roller pairs which corresponds to the radius of curvature of the rail 10. The backrest 2 and the frame structure 4 will thus be swung around the point E, which is conveniently located in the region of the common centre of gravity of the backrest and the seat cushion, including a person seated thereon. The embodiment illustrated in Figures 3 and 4 is analo¬ gous with the embodiment illustrated in Figures 1 and 2 and operates in a similar manner, wherein those elements in Figures 3 and 4 which at least correspond essentially to the elements illustrated in Figures l and 2 have been identified with the same reference numerals. The embodiment illustrated in Figures 3 and 4 differs from the embodiment illustrated in Figures 1 and 2 mainly as follows: The base mount 1 supports the backrest 2 through the intermediary of a suitable supportive projection 5 in the form of a rotatably journalled support roller, and an arm 6 which has a first, forwardly angled end-part 7 and the other end-part of which is pivotally journalled in the base mount 1. The arm 6 is pivotally journalled in the front region of the frame structure 4 at a point 9 located between said end-parts. When comparing Figure 3 with Figure 4, it will be seen that the arm 6 extends obliquely rearwards and upwards when the backrest 2 is located in its maximum upright position, and obliquely forwards and upwards when the backrest is in its maximum rearwardly inclined position. The rearward region of the frame structure 4 has an abutment surface 10 which rests against the supportive projection 5. In the illustrated seat embodiment, the surface 10 forms the upper defining surface of a slot which, when the backrest is raised, extends generally obliquely rearwards and upwards and the end surfaces of which determine the extremities to which the backrest 2 can be raised and lowered, by engagement with the supportive projection 5. When the backrest is in its upright, raised position, the abut¬ ment surface 10 has, advantageously, an obliquely rear- wardly and upwardly curved extension. In the illustrated embodiment, the seat cushion 3 has a flat abutment surface 12 which, in a forward region of the seat, lies against a convex support surface 13 on the end-part 7 of the arm 6. It will be seen that the surfaces 12, 13 contact one another essentially along a line which extends perpendicularly to the plane of the drawing and whose position along the surfaces 12, 13 will be dependent on the position to which the arm 6 is swung. The curvature of the support surface 13 is chosen so that the height of the front edge of the seat cushion 3 above the floor will decrease as the backrest 2 is swung from its upright position to its rearwardly in¬ clined position. It will also be understood that instead of one straight abutment surface 12 and one curved support surface 13 which determines the height of the front edge of the seat cushion above the floor, the seat cushion may be provided with a curved seat-height determining abutment surface and the arm part 7 may be provided with a sup¬ port surface in the form of a support runner, for in¬ stance. As a result of the inventive seat supporting construction, the seat provides a favourable sitting position, for instance, from the aspect of work perfor¬ mance, when the backrest is in its upright position, and will provide a favourable seating position from a rest¬ ing aspect when the backrest is in a rearwardly inclined position, with the angle of the backrest and the seat cushion changed and the seat cushion adjusted to a lower height above the ground, without encroaching unduly on the space provided for a person seated immediately behind the seat. It will be seen that in practice the frame structure 4 and the seat cushion 3 are supported from beneath on opposite sides of their respective back and/or front end-parts. For instance, the seat cushion 3 can be supported on opposite sides of its back region and/or of its front region. Furthermore, the frame structure 4 may include two rails 10 which are separated in the trans¬ verse direction of the seat and each of which is guided by a respective support 5. It will also be understood that the curved track 23 may be mounted on the seat cushion 3 and the runner 31, 33 mounted on the base mount l as an alternative to the embodiment illustrated in Figures 3 and 4. The inventive arrangement may also include air springs which assist in moving a rearwardly inclined backrest to its upright position in a conventional manner, and means may be provided for locking the seat in any selected position between the limit positions shown in Figures 1 and 2. The invention is not therefore restricted to the afore- described and illustrated exemplifying embodiments thereof, but can be realized in any desired manner within the scope of the inventive concept defined by the following Claims.

Claims: Claims 1. A seat comprising a base mount (1) which supports an a justable backrest (2) and a seat cushion (3) whose rear part is pivotally supported by the backrest (2) and whose forward part has a supportive part (31, 33; 12) which is dispiaceably carried by the base mount (1) , wherein the arrangement is such that the bottom part of the backrest (2) and the seat cushion (3) are moved forwards relative to the base mount (1) as the backrest (2) is inclined rearwardly from an upright position, c h a r a c t e r i z e d in that the backrest (2) has firmly connected thereto a frame structure (4) which extends in beneath the seat cushion (3) ; in that the frame structure (4) is dispiaceably carried by a support (5', 5"; 5, 6, 8, 9) mounted on the base mount (1) and has a guide (10) which coacts with the support (5', 5"; 5) and which in the upright position of the backrest (2) extends generally rearwards and upwards; and in that a supporting arrangement (23, 6, 7, 8, 13) connected to the base mount (1) supports the front supporting part (31, 33; 12) of the seat cushion (3) for movement along a predetermined movement path (23); and in that the guide (10) and the movement path (23) have extensions such that the height of the front edge of the seat cushion (3) above the floor will be held generally constant or will decrease as the backrest (2) is swung from its upright position to a rearwardly inclined position. 2. A seat according to Claim 1, c h a r a c ¬ t e r i z e d in that the support arrangement (23) and the supporting part (31, 33) coacting therewith include a guide path (23) and a runner (31, 33) coacting there- with. 3. A seat according to Claim 2, c h a r a c ¬ t e r i z e d in that the guide path (23) is firmly mounted on the base mount (1) ; and in that the runner (31, 33) is connected to the seat cushion (3). 4. A seat according to Claim 2 or 3, c h a r a c ¬ t e r i z e d in that the runner includes a roller (33) which runs along the guide path (23). 5. A seat according to Claim 1, c h a r a c ¬ t e r i z e d in that the support which coacts with the guide (10) includes two mutually separate roller pairs (52, 53) on the base mount (l), said guide (10) running between the rollers (52, 53) of respective roller pairs. 6. A seat according to Claim 1, c h a r a c ¬ t e r i z e d in that the support arrangement (6, 7, 8, 13) includes at least one arm (6) which with the aid of one first end-part (7) supports the seat cushion (3) in a forward region thereof, and which is pivotally carried by the base mount (1) at its opposite end-part (8); in that said support part is an abutment surface (13) which is arranged on the seat cushion (3) and which coacts with a supporting surface (13) on the aforesaid first end-part (7) of the arm (6) ; in that the supporting surface (13) and the abutment surface (12) are in con¬ stant abutment with one another along a limited region whose position is dependent on the position to which the arm (6) is swung; in that the support is formed partly by virtue of the fact that the front region of the frame structure (4) is supported by the arm (6) and pivotally connected to said arm at a point between the mutually opposite end-parts thereof; and in that the arm has different pivotal positions when the backrest is in its upright position and when the backrest is in a rear¬ wardly inclined position, and also by virtue of the fact that the guide rail (10) rests dispiaceably against a supportive projection carried by the base mount (1). 7. A seat according to Claim 6, c h a r a c - t e r i z e d in that the arm (6) has a forwardly angled first end-part (7) which includes a generally upwardly facing convex support surface (13) which coacts with a preferably flat abutment surface. 8. A seat according to Claim 6 or 7, c h a r a c ¬ t e r i z e d in that the convex support surface (13) is located forwardly of the connecting point (9) between the frame structure (4) and the arm (6) ; and in that the radius of curvature of the support surface (13) decreas- es in a rearward direction. 9. A seat according to Claim l or 6, c h a r a c ¬ t e r i z e d in that the frame structure guide (10) has an obliquely rearwardly and upwardly curved exten- sion when the backrest (2) is in its upright position. 10. A seat according to Claim l or 6, c h a r a c ¬ t e r i z e d in that the pivotal connection (11) between the rear region of the seat cushion (3) and the backrest (2) is located at a considerable distance beneath the seating surface of the seat cushion (3) so that the seat cushion (3) will be moved forwards rela¬ tive to the frame structure (4) as the backrest (2) is inclined rearwardly.

Inventors: BERGKVIST HAAKAN, LARSVALL JOHAN, BERGKVIST, HAAKAN, LARSVALL, JOHAN
Applicants: NOCO STOLAR AB, AB NOCO-STOLAR
Application year: 1993
Main classification: A47C1
IPC codes: A47C1