A CHAIR

Abstract: A chair includes a seat (4) and a backrest (5). The seat (4) includes a front seat part (41) which is carried by a chair base structure (1, 2, 7, 71), and a rear seat part (42) which borders on the front seat part (41) along a join line that extends generally perpendicular to a symmetry plane of the chair (3). The chair includes means (7) for selectively adjusting the distance between the seat join line (43) and the backrest (5) so as to enable a chair user sitting on the seat (4) with his back in contact with the backrest (5) to take a sitting position in which his hip joints lie generally in a vertical plane that includes the join line (43). Means (8, 9, 14, 15, 16) are provided for moving the rear seat part (42) vertically relative to the front seat part (41). Said means include a lever (9) and a support point (15) which is stationary relative to the front seat part (41). The blocking device (14) has a variable length and, in one end position, functions to cause the lever (9) to hold the rear seat part (42) flush with the front seat part (41). The chair also includes a triggering device (16) which upon manual activation functions to reduce the length of the blocking device (14) and thereby lower the rear seat part (42) relative to the front seat part.

Description: A CHAIR The present invention relates to a chair of the kind defined in the preamble of Claim 1. A chair of this kind is known from WO 97/10735. The invention thus relates to a chair of the kind which includes a seat and a backrest, wherein the seat includes a front part which is supported by a chair base, and a rear part which borders on the front part of the seat along a join line which extends generally parallel with the intersection between the seat and the backrest, wherein means are provided for selectively adjusting the horizontal distance between the seat join line and the backrest, and wherein means are provided for moving the rear seat-part vertically relative to the front seat-part. The user of such a chair adjusts the distance between the backrest and the join line so that a vertical plane through the hip joints of the user will coincide generally with the join line, when the user rests his back against the backrest with his upper body generally straight and with his buttocks seated on the chair seat. Assuming that the upper surfaces of the rear and the front seat-parts lie generally in one and the same plane, i.e. are essentially flush with one another, most of the user's weight will be supported by the rear part of the seat. When the rear part of the seat is lowered, a large part of the earlier load on the rear part of said seat (or the whole of said load) is likely to be transferred to the front part of the seat. Because the join line is set so as to coincide with the vertical plane through the wearer's hip joints (or immediately beneath the ischial tuberosities) , the increase in weight will not result in any upward rotary force against the user's thighs. The friction between the backrest of the chair and the user's spine will take-up part of the user's weight. That part of the user's buttocks supported by the rear part of the seat is now able to sag and therewith subject the lumbar region of the wearer's back to traction. By restricting vertical downward movement of the rear part of the seat, the user is able to adjust the seat for desired traction of the lumbar region and/or to adjust the chair for desired transfer of load from the rear part of the seat to its front part. The object of the present invention is to provide a simple construction which can be readily manufactured and easily fitted and which can be easily manoeuvred by the mechanism that supports the rear part of the chair seat. Another object is to provide a construction which can be readily fitted to a typical chair base, for instance of the kind which enables the chair to be tilted, raised, twisted or moved in some other way relative to the chair support base. These objects are achieved with a chair constructed in accordance with the accompanying Claim 1. 3 Further embodiments of the inventive chair will be apparent from the accompanying dependent Claims. In preferred embodiments of the invention, the longitudinal axis of the blocking device extends generally parallel with the longitudinal axis of the chair. The blocking device may consist of a gas spring which is spring-biased so as to return the rear part of the seat to its terminal position in which it lies flush with the front part of the seat, in the absence of load on the rear part of said seat and upon activation of the trigger mechanism. The gas spring will conveniently include a valve means which can be activated by the trigger mechanism and which separates the primary gas- pressure applying chamber of the gas spring from the secondary gas chamber thereof. The through-passage of the open valve may be adapted to restrict the speed at which the piston rod/piston of the gas spring moves in relation to the cylinder part of said spring. By suspending the rear part of the seat from a so-called bell-crank lever which is pivotally mounted on the front part of the seat, the means for moving the rear part of the seat vertically can be given a small structural height and can be supported by the front part of the seat. The invention will now be described with reference to an exemplifying embodiment thereof and also with reference to the accompanying drawings, in which Fig. 1 is a schematic side view of a chair constructed in accordance with the invention; 4 Fig. 2 is a view taken on the line II-II in Fig. 1; Fig. 3 is a schematic sectional view taken on the line III- III in Fig. 2; and Fig. 4 is a schematic, partially sectioned view of the arrangement shown in Fig. 1. Shown in Fig. 1 is a chair base structure 1 that includes conventional means 2 for raising/lowering, tilting, twisting or rotating a chair seat 4 that forms part of a chair 3 constructed in accordance with the invention. The chair also includes a backrest 5, which is supported by the base structure 1. The backrest 5 is also supported by a device 6 which enables the backrest to be raised/lowered, tilted, twisted or moved in some other fashion. The illustrated chair seat 4 is carried by a slide 7 which can be moved horizontally towards and away from the backrest 5, which can therewith be held in a fixed position relative to the base structure 1. The slide 7 can be locked in a desired position with the aid of means not shown. The chair seat 4 includes a front part 41 and a rear part 42, wherewith the join line 43 between the seat parts 41, 42 is generally parallel with the intersection line between the seat 4 and the backrest 5. The join line 43 shall have the extension described in more detail in WO 97/10735, the teachings of which are incorporated in the present document. The slide supports the front part 41 of the seat with the aid of two mutually spaced and mutually parallel plate profiles 71. A horizontal pivot shaft 8 is carried between the profiles 71. The pivot shaft 8 supports the knee or fulcrum point of a bell-crank lever 9, the arms 10, 11 of which lie in a vertical plane which includes the longitudinal axis of the chair and which preferably constitutes a chair symmetry plane. The longer arm 10 of the lever 9 extends rearwardly from the front part 41 of the chair and carries the rear part 42 of said chair. The arm 10 is suitably designed so as to strike against the undersurface of the front seat-part 41 in an outwardly swung position, wherewith the top surfaces of the two seat-parts 41, 42 lie essentially in a common plane, at least in the region of the join 3. Extending between the front parts of the profiles 71 is a horizontal rotatable shaft 15 that has a transversal threaded opening 151 which receives a threaded end-part of a piston rod 143 projecting forwardly from a cylinder body 142 belonging to a gas spring 14, the rear end-part 41 of which is pivotally mounted on a pivot point 12 on the shorter arm 11 of the bell-crank lever 9 , at a distance beneath the pivot mounting 8 of said arm. The gas spring 14 is of conventional design and includes a trigger mechanism rod 144 which extends centrally and coaxially through the piston rod 143 and projects out from the front end of said rod. The trigger mechanism rod 144 operates a valve 145. The spring includes a piston or plunger 146 which divides the cylinder 142 into two chambers 147, 148. In the illustrated case, the chamber 148 contains a mechanical spring 149 which biases the gas spring 14 towards its maximum length. o Located at the bottom edge of the front edge of the front seat-part 41 is a trigger mechanism 16 which includes a bell- crank lever 161 which is pivotally mounted at its knee or fulcrum point on a stationary shaft 162 that extends parallel with the aforesaid shafts 8 and 15. In the non-activated state of the trigger mechanism 16, a generally upwardly extending arm 163 is located immediately in front of the end of the rod 144 and positioned above the pivot shaft 162. The other arm 164 of the bell-crank lever extends forwardly and can be raised by the user, therewith causing the bell-crank lever 9 to be swung clockwise in Fig. 1 under the influence of a load on the rear part 42 of the seat, so as to lower said seat-part 42 in relation to the front seat-part 41. As soon as the trigger mechanism 16 is released, the valve 145 is closed so that load acting vertically downwards on the seat-part 42 will be captured by the gas spring 14 while compressing gas enclosed in the chamber 148. The shaft 15 is mounted for rotation about its axis . The invention can be modified in several respects For instance, the gas spring 14 can be replaced with a setting device or adjuster that is driven by an electric motor and operates between the shafts 12 and 15. In this regard, a trigger mechanism in the form of an electric switch can be placed at any desired position to enable selective raising/lowering of the rear part of the seat relative to the front part thereof. Another alternative is to provide a trigger mechanism in the form of, e.g., a purely mechanical blocking device coupled to operate between the points 12 and 15 with the aid of an operating lever that can be swung forwardly/rearwardly by the user to set the relative height position of the rear part 42 of the seat. The blocking device will preferably be self-latching, i.e. adapted to latch at least in the compression direction, when the trigger mechanism is released. In another embodiment of the invention, the blocking device may act directly between the slide 7 and the arm 10 of the lever. The plate profiles 71 form spacing elements and define a vertical space in which the arrangement for raising/lowering the seat-part 42 can be placed. The profiles 71 can be mounted directly on a conventional seat base 1, 2, at least in the case of office chairs and the like. It will be understood, however, that the base structure 1, 2 and also the backrest suspension 6 can be given some other design in the case of chairs intended for ships, boats and motor vehicles.

Claims: 8 CLAIMS 1. A chair that includes a seat (4) and a backrest (5), wherein the seat (4) includes a front seat part (41) which is carried by a seat base structure (1, 2, 7, 71), and a rear seat part (42) which borders on the front seat-part (41) along a join line which extends generally perpendicularly to a chair symmetry plane, wherein the chair includes means (7) for selectively setting or adjusting the distance between the seat join line (43) and the backrest (5) so that a chair user sitting on the seat (4) with his back in contact with the backrest (5) can take a sitting position in which his hip joints lie generally in a vertical plane that includes the join line (43), and wherein means (8, 9, 14, 15, 16) are provided for moving the rear seat-part (42) vertically in relation to the front seat part (41), characterised in that the vertical movement means (8, 9, 14, 15, 16) include - a lever (9) means which is pivotally mounted (8) on the front seat part (41) and which supports the rear seat part (42) for vertical movement; - a blocking device (14) which is adapted to operate between the lever means (9) and a support point (15) which is stationary relative to the front seat part (41), wherein the blocking device (14) has a variable length and in one terminal position functions to cause the lever means (9) to hold the rear seat part (42) flush with the front seat part (41); and - a trigger mechanism (16) which when actuated manually causes the length of the blocking device (14) to be reduced and therewith lower the rear seat part (42) in relation to the front seat part. 2 . A chair according to Claim 1, characterised in that the lever (9) is a bell-crank lever; and in that the blocking device (14) is orientated to establish a length variation generally in a horizontal direction parallel with the chair symmetry plane. 3. A chair according to Claim 1 or 2 , characterised in that the blocking device (14) is a gas spring that includes a latching device (144, 145) and a mechanical spring (149) which acts in a direction in which it strives to return the rear seat part to the same level as that occupied by the first seat part (419. 4. A chair according to Claim 3 , characterised in that the gas spring comprises a cylinder (142) that includes a piston (146) having a valve means (145), said piston (146) being connected to a piston rod (143); in that the lever (9) is a bell-crank lever which includes a arm (11) that extends downwardly from the pivot point ( 8 ) , wherein the cylinder (142) of the gas spring (14) is pivotally mounted on a pivot point (12) at the free end of the lever arm (11), and wherein the piston rod (143) of the gas spring is fixedly connected to the support point (15); in that the latching means (144, 145) includes a rod that extends coaxially through the piston rod (143) and projects out from the free end of said piston rod; and in that a trigger mechanism (16) is pivotally mounted (162) on the front seat part (41) to permit the rear seat part (42) to be lowered when activated.

Inventors: RINNE KARI, RINNE TOMMI, RINNE YRJOE, RINNE, KARI, RINNE, TOMMI, RINNE, YRJOE
Applicants: RINNE KARI, RINNE TOMMI, RINNE YRJOE, RINNE, KARI, RINNE, TOMMI, RINNE, YRJOE
Application year: 1999
Main classification: A47C7
IPC codes: A47C7