CHAIR WITH MOVABLE SEAT AND BACKREST

Abstract: Chair comprising a support element (1) ,a seat (2) and a backrest (3), the seat (2) consisting of a foremost portion (7) being rigidly connected to the support element (1) and of a rear portion (8) being pivotally connected to the support element (1) and being supported by an arm (13) at some distance from its pivot (10), said arm (13) being positioned beneath the seat (2) and carrying the backrest (3). Said arm (13) being pivotally connected to the support element (1) and being biased by a progressively acting spring member (17) towards the position which the rear seat portion (8) and the backrest (3) are occupying in the unloaded state.

Description: The invention relates to a chair comprising a support element, a seat and a backrest, the seat consisting of a foremost portion being rigidly connected to the support element and a rear portion being pivotally connected to the support element and engaging the foremost portion, said rear portion and said backrest being biased by at least one spring member towards that position which these parts are occupying in the unloaded state, whereby the rear seat portion is supported by an arm at some distance from its pivot said arm carrying the backrest and being pivotally connected to the support element at a point located beneath the seat and as seen in plan view, being located between the pivot of the rearward seat portion and the point where this seat portion is supported by said arm. Such a chair is known from EP-A-0 105 955. In case of this known chair the spring member is in the shape of a bent wire or strip. If such a spring member is loaded the force exerted by it will increase substantially linearly. So the angle over which the rear seat portion and the arm carrying the backrest are pivoted, will linearly vary with the weight of the person using said chair. By means of an additional adjustable spring member the chair can be made comfortable for a person with a given weight. So such a chair is substantially intended to be used by one and the same person. The object of the invention is to provide a chair with such a sitting comfort that it can be used in public areas, cantines, district centers, etc., in which the chair is used under various conditions and by persons with different weights and shapes. In that case the chair has to offer an optimal sitting comfort to the person using it during various conditions of use, so sitting positions. According to the invention as defined in the characterising portion of Claim 1, this is achieved in that said spring member is positioned between the pivots of said rear seat portion and said arm and being formed by a progressively acting spring member in the shape of at least one block microcellular polyurethane being located between said arm and a member which is fixedly connected to said support element. When applying the above indicated features it is achieved that the chair is offering the desired sitting comfort for persons with a very different weight. By the weight of the user via the rear seat portion a force will be exerted on the arm carrying the backrest so that said arm will have the tendency to pivot over a specific angle, said pivoting being opposed by said progressively acting spring member. By the particular shape and positioning of said spring member a more pleasant construction will be attained requiring less space. While in the above mentioned patent application it is remarked that the foremost seat portion has a width being about twice the width of the rear seat portion, according to the present invention and defined in dependent Claim 2 it has appeared that the best sitting comfort is obtained when the width of the foremost fixed seat portion, as seen in horizontal direction from the forward edge up to the pivot of the rear seat portion, is within the range of 130 to 200 mm, when the distance between said pivot and the point where the arm is pivotally connected to the support element is substantially equal to the distance between the pivot of the said arm and the point where the rear seat portion is supported by said arm and when said distances are in the range of 100 to 120 mm. This means that the width of the rear seat portion is larger than twice the width of the foremost seat portion. Now the invention will be further elucidated with reference to an embodiment, shown in the drawing, in which: Fig. 1 schematically shows a side view of a chair according to the invention, in which for the sake of clearness specific parts have been deleted; and Fig. 2 shows a view according to Fig. 1, but with the rear seat portion and the backrest in a pivoted position. The shown chair comprises a support element 1, a seat 2 and a backrest 3. The support element 1 comprises four legs 4, which are interconnected by the beams 5 and 6. The seat 2 consists of the foremost portion 7 which is fixedly connected to the support element 1, and of the rear portion 8. The seat portion 8 is provided with lugs 9 near the foremost edge engaging the seat portion 7, through which lugs the shaft 10 extends, which on the other hand is running through lugs 11 connected to the support element 1. Further the seat portion 8 is provided with a projection 12 which rests on an arm 13 being fixedly connected to the back rest 3. The arm 13 is pivotally supported by the shaft 14, which in a manner not shown, is connected to the support element 1. Between the foremost portion 15 of the arm 13 and an element 16 fixedly connected to the support element 1 the spring member 17 is mounted. This member consists of one or more blocks of microcellular polyurethane providing a progressive spring characteristic. As already said above the width a of the fixed foremost seat portion 7 in particular will be within the range of 130 to 200 mm. The distance b between the pivots 10 and 14 preferably will be substantially equal to the distance c between the pivot 14 and the projection 12. In this the distances b and c will be within the range of 100 to 120 mm and preferably will be 110 mm. In this the distance c is measured in the unloaded state of the seat portion 8 and will become slightly smaller when the seat portion 8 is pivoting in the direction of the arrow P when a person is sitting down of the seat portion 8. Depending on the position the relating person will assume, the seat portion 8 will pivot more or less for example to the position shown in Fig. 2, during which the backrest 3 will rotate over a larger angle, to wit over an angle which is about twice as large as the angle over which the seat portion 8 is rotated. The rotation of the seat portion 8 and of the backrest 3 will be limited by the progressively acting spring member 17. It will be obvious that only a possible embodiment of a chair according to the invention is shown in the drawing and has been discussed above and that many modifications may be applied without departing from the inventive concept as defined in the appended Claims. So for example it is possible to construct the support element in a completely different way so as in the shape of a column with at its lower end laterally extending legs. All these possibilities, however, will be obvious for an expert and do not need further elucidation.

Claims: Chair comprising a support element (1), a seat (2) and a backrest (3), the seat (2) consisting of a foremost portion (7) being rigidly connected to the support element (1) and a rear portion (8) being pivotally connected to the support element (1) and engaging the foremost portion (7), said rear portion (8) and said backrest (3) being biased by at least one spring member (17) towards that position which these parts (8,3) are occupying in the unloaded state, whereby the rear seat portion (8) is supported by an arm (13) at some distance from its pivot (10) said arm (13) carrying the backrest (3) and being pivotally connected to the support element (1) at a point (14) located beneath the seat (2) and as seen in plan view, being located between the pivot (10) of the rearward seat portion (8) and the point where this seat portion (8) is supported by said arm (13), characterized in that said spring member (17) is positioned between the pivots (10,14) of said rear seat portion (8) and said arm (13) and being formed by a progressively acting spring member (17) in the form of at least one block microcellular polyurethane being located between said arm (13) and a member (16) which is fixedly connected to said support element (1). Chair according to claim 1, characterized in that the width (a) of the foremost fixed seat portion (7), as seen in horizontal direction from the forward edge up to the pivot (10) of the rear seat portion (8) is within the range of 130 to 200 mm, the distance (b) between said pivot (10) and the point (14) where the arm (13) is pivotally connected to the support element (1) being substantially equal to the distance (c) between the pivot (14) of said arm and the point where the rear seat portion (8) is supported by said arm (13), said distances being in the range of 100 to 120 mm.

Inventors: BOOMSMA, HARM, LEWERISSA, RONALD, VAN ZEE, ERIC, VERBRUGGE, JEROEN
Applicants: AHREND GROEP B.V.
Application year: 1987
Main classification: A47C1
IPC codes: A47C7, A47C3, A47C1