TILTING MECHANISM FOR A CHAIR

Abstract: Mechanism for a chair, especially an office chair, comprising a biased back support (5) and a seat (4) being synchronously movable with the back support (5), the spring (2) for the seat (4) as well as for the back support (3) being arranged in the journalled axis (2) for the back support (3) in the frame (1) of the mechanism, the seat (4) being journalled near the front edge, to the frame (1) with a shaft (6) being arranged horizontally and vertically in a distance from the journalling axis (2) of the back support, the seat (4) being journally connected with a shaft (7) on a support arm (3) to which the back support (5) is connected by means of a connection piece (9) by which the difference between the rotation radius around the shaft (7) and the radius of the rotation of the seat (4) around the shaft (6), is compensated.

Description: TILTING MECHANISM FOR A CHAIR The present invention is related to a tilting mechanis for a chair, according to the preamble of the claim. s Tilting mechanism for chairs, especially for offic chairs, are available in a number of different varieties, partly for tilting only of the back portion of the chair, partly for tilting of the seat and the back portion together. Synchronous tilting of seat and back portion partly is achieved by a spring 0 for the seat and a spring for the back portion whereas recently developments are found where seat and back portion are tilted synchronously with only one spring. Even if the tilting of the seat and the back portion is performed synchronously, the seat does not necessarily maintain its position in relation to the back portion during the movement, but the angle between the seat and the back portion to the contrary is changed in dependency of the tilting angle of the back portion. It is, however, substan¬ tial for the comfort of a chair to provide a desired angle relationship between the seat and the back portion in all different positions of the back portion. To achieve such a tilting movement both of the back portion and the seat, seat and back portion both are journalled on their own horizontal tilting axis. The geometrical relation¬ ships, such as the arrangement of these two axis in relation to each other, horizontally as well as vertically, and the arrange¬ ment and the shape of the connection between the seat and the back portion, are crucial for the relative tilting movements of the seat and the back portion. With the tilting mechanism according to the present invention, relative movements between seat and back portion are achieved which ensures that the so called stripping effect is avoided, this means that the rear portion of the seat is moved so much downwards in relation to the back portion when this is tilted backwards, that shirts are pulled up from trousers. This effect is achieved additionally to the fact that the front edge of the seat is maintained substantially in the same position and that there is provided a possibility of adjustment of the arrangement of the seat towards the front and towards the rear of on the chair. The only Figure of the drawing discloses schematically a side view of a tilting mechanism according to the present invention where one tilting position of the mechanism is disclosed with dotted lines, s The frame 1 of the mechanism is secured to a chair base (not disclosed) and rotatable around the axis 12. In the frame is arranged is arranged a spring 2 between the frame 1 and an arm 3 protruding outwards and backwards, on which a back support (5) is secured, such as by a nut 10. The arm 3 is moved against the force of the spring when a user leans backwards and thereby presses the back support backwards and downwards, turning around the axis 2. The seat 4 is journalled around a shaft 6 in the front portion of the frame 1. The shaft 6 may be connected with the frame 1, may be biased in relation to the frame or may be adjustable in relation to the frame. The seat 4 is connected with the shaft 6 in such a way that the seat may be displaced forwards and backwards as the shaft 6 is sliding in guidings 11. Correspondingly the rear portion of the frame also is journalled along the shaft 7 in a guiding 8, whereby the shaft 7 may be locked to the guiding 8, such as by a nut. The shaft 7 is connected with the seat 4 by a middle piece 9. The middle piece 9 may be fixedly secured to the seat 4 and flexible such that it can turned around the shaft 7. On the other hand the middle piece 9 may be a short arm (not disclosed) journalled to the shaft 7 and also journally secured to the seat 4. By means of the middle piece 9, the back portion 5 and the seat 4 may be tilted around the axis of the spring 2 and the axis of the shaft 6 respectively as the displacement between the seat and the arm 3 will be adjusted by the flexibility of the flexible middle piece 9 as disclosed or by a rigid middle arm.

Claims: P a t e n t C l a i m s 1. Mechanism for a chair, especially an office chair, comprising a biased back support (5) and a seat (4) bein synchronously movable with the back support (5), CHARACTERIZED IN the spring (2) for the seat (4) as well as for the back support (3) is arranged in the journalled axis (2) for the back support (3) in the frame (1) of the mechanism, the seat (4) being journalled near the front edge, to the frame (1) with a shaft (6) being arranged horizontally and vertically in a distance from the journalling axis (2) of the back support, the seat (4) being journally connected with a shaft (7) on a support arm (3) to which the back support (5) is connected by means of a connection piece (9) by which the difference between the rotation radius around the shaft (7) and the rotation radius for the seat (4) around the shaft (6), is compensated. 2. Mechanism according to claim 1, CHARACTERIZED IN the seat (4) being displaceable in and out in relation to the frame (1) in that the shaft (6) connected with the front portion of the frame (1) is displaceable in a guiding (11) secured to the front portion of the seat (4) and the shaft (7) being displaceable in a guiding (8) secured to the support arm (3). 3. Mechanism according to claims 1-2, CHARACTERIZED IN the front shaft (6) on the frame (1) being vertically adjustable for adjusting the height of the seat. 4. Mechanism according to claim 1-2, CHARACTERIZED IN the front shaft (6) of the frame (3) being vertically biased.

Inventors: LIE TORE, LIE, TORE
Applicants: RING MEKANIKK AS
Application year: 1992
Main classification: A47C9
IPC codes: A47C1