Chair

Description

The invention relates to a chair having a seat, a backrest, a support frame, and a seat suspension that is formed by at least one S-shaped leaf spring.

In practice, synchronous mechanisms for synchronously adjusting the seat and the backrest are known, with the backrest and the seating surface being flexibly coupled to one another and moving relative to one another in a fixed ratio, for example 3:1 or 2:1. Different swivel mechanisms via which the backrest and the seat are coupled have been developed for implementing the synchronous mechanism. One or more spring elements cushion the synchronous movement.

A chair having a seat, a backrest, and a support frame is known from EP 2 047 769 B1. The seat is supported by a seat support and the backrest is supported by a back support, the seat support and the back support being made up of at least one rocking spring, and together forming an S-shaped spring element having at least two sections with different spring strengths that are formed from separate spring elements. The effective spring length of the rocking spring may be adjusted via an adjustment element due to the presence of a second element that accompanies the rocking spring. In addition, a slider is provided that connects the rocking spring to the second element. Depending on the location of this slider, a longer or shorter portion of the rocking spring is able to deform independently of the second element.

Furthermore, US 2002/0000745 A1 relates to a patient chair having a seat, a backrest, a support frame, and two S-shaped leaf springs, with the S-shaped leaf springs at a first section being fastened to the support frame via a crossmember, the seat being mounted on a second section, and the backrest being mounted on a third section, and a first curvature being provided between the first and second sections, so that in a neutral position of the chair the first section and the second section are situated essentially in parallel to one another and spaced apart, and the third section adjoins the second section via a second, opposite curvature. In addition, the second section is supported on the crossmember via a first spring element. During a downwardly directed seat movement, the first spring element is compressed and ultimately comes into operative contact with a second spring element provided between the first and the second section. The two spring elements allow a stable, self-damping swivel movement of the seat and the backrest, and limit a maximum tilted position of the chair.

The object underlying the invention is to improve the adjustability of the swivel movement.

This object is achieved according to the invention by the features of claim 1. Further embodiments of the invention are the subject matter of the subclaims.

The chair according to the invention has a seat, a backrest, a support frame, and at least one S-shaped leaf spring, the S-shaped leaf spring at a first section being fastened to the support frame, the seat being mounted at a second section, and the backrest being mounted at a third section, and a first curvature being provided between the first and second sections, so that in a neutral position of the chair the first section and the second section are situated essentially in parallel to one another and are spaced apart, and the third section adjoins the second section via a second, opposite curvature. A compressible spacer that is displaceably guided in the longitudinal direction of the first section is provided between the first and the second section.

The displacement of the compressible spacer along the first section allows the effective lever arm of the second section to be changed, so that the firmness of the leaning-back movement may be adjusted and in particular adapted to different user weights.

Preferably only one S-shaped leaf spring, which is situated mirror-symmetrically with respect to the longitudinal center plane of the chair, is provided. On the one hand this reduces the number of components, and on the other hand facilitates a lateral swivel movement of the seat and the backrest. A chair designed in this way thus also allows three-dimensional dynamic seating.

According to one preferred embodiment of the invention, the compressible spacer is situated in a middle area of the first section, between the fastening to the support frame and the first curvature. In addition, the compressible spacer with a first contact surface may be displaceably guided on the first section, and at its opposite end may have a second contact surface on which the second section of the S-shaped leaf spring is preferably loosely supported.

For displacing the compressible spacer, the first section of the S-shaped leaf spring preferably has at least one recess that extends in the longitudinal direction of the first section. In this way the effective lever arm of the second section of the leaf spring, and thus the elastic force, may be easily changed by moving the compressible spacer.

It may also be provided that the compressible spacer is connected to an actuating element for displacing the compressible spacer along the recess and for detachably fixing the compressible spacer in a desired position. A particularly simple and intuitive adjustment may be achieved when the actuating element is designed in such a way that a rotation of the actuating element brings about a simultaneous displacement of the compressible spacer along the recess. This could be achieved, for example, by designing the recess as an elongated hole with toothing, and the actuating element being in operative engagement with the toothing, so that a rotation of the actuating element brings about a simultaneous displacement of the compressible spacer along the recess. The actuating element and the elongated hole provided with the toothing may thus intermesh, in particular in the manner of self-locking lantern gear toothing.

The S-shaped leaf spring is preferably made of steel. Compared to plastic or glass fiber-reinforced plastic, steel has the advantage of a significantly smaller CO2 footprint. In addition, the spring behavior of steel is perceived by the user as “snappier” and thus pleasantly dynamic. Within the scope of the invention, it has advantageously been shown that when the steel has a yield strength of greater than 500 MPa an elastic return is ensured, even for fairly high user weights. A further reduction in the CO2 footprint may be achieved by manufacturing the seat and the backrest from plywood.

In order for the chair not to be perceived as too “soft” when leaning back, it is advantageous for the compressible spacer to have a progressive spring characteristic curve. For example, a coil spring made of steel and/or a Cellasto disk are/is suitable as a compressible spacer.

According to a further embodiment of the invention, the S-shaped leaf spring is deflectable with regard to both bending and rotation. Three-dimensional dynamic seating is thus made possible so that the seat and the backrest may be swiveled not only backward, but also laterally. The compressible spacer is therefore designed so that it also supports the lateral swivel movement by also being laterally compressible. In addition, the recess extending in the longitudinal direction of the first section may also be designed in such a way that rotation of the first section about a longitudinal center axis of the first section, and thus the lateral swiveling, are facilitated.

Armrests that are fastened to the seat or to the second section of the S-shaped leaf spring may optionally also be provided on the chair.

Further embodiments of the invention are explained in greater detail, based on the following description and the drawings.

In the Drawings:

FIG. 1 shows a schematic side view of the chair with a spacer in a rear position,

FIG. 2 shows a schematic side view of the chair with a spacer in a front position,

FIG. 3 shows a schematic illustration of the S-shaped leaf spring with a compressible spacer in the front position,

FIG. 4 shows a schematic illustration of the S-shaped leaf spring with a compressible spacer in the rear position,

FIG. 5 shows a three-dimensional bottom view of the illustration according to FIG. 4,

FIG. 6 shows a sectional illustration in the area of the compressible spacer,

FIG. 7a-7h show schematic illustrations of the lantern gear toothing in various positions of the actuating element,

FIG. 8 shows a schematic side view of the chair according to FIG. 1 in the tilted-back position,

FIG. 9 shows a schematic side view of the chair according to FIG. 2 in the tilted-back position,

FIG. 10 shows a schematic front view of the chair according to FIG. 1 in a laterally tilted position, and

FIG. 11 shows a schematic front view of the chair according to FIG. 2 in a laterally tilted position.

The chair illustrated in FIGS. 1 through 6 is made up essentially of a seat 1, a backrest 2, a support frame 3, and at least one S-shaped leaf spring 4, with the S-shaped leaf spring 4 at a first section 4a being fastened to the support frame 3, while the seat 1 is mounted on a second section 4b and the backrest 2 is mounted on a third section 4c. A first curvature 4d is provided between the first and the second section, so that in the neutral position shown in FIG. 1, the first section 4a and the second section 4b are situated essentially in parallel to one another and spaced apart, and the third section 4c adjoins the second section 4b via a second, opposite curvature 4e.

The support frame 3 has a central column 3a and a cross-shaped base 3b with rollers 3c.

However, within the scope of the invention other support frames are conceivable, in particular those with fixed feet.

In addition, in the illustrated exemplary embodiment armrests 5 which are fastened to the seat 1 or to the second section 4b of the S-shaped leaf spring 4 are provided. Furthermore, provided between the first section 4a and the second section 4b is a compressible spacer 6 that is displaceably guided in the longitudinal direction of the first section 4a. FIG. 1 shows the compressible spacer 6 in a rear position, while a front position is illustrated in FIG. 2. The compressible spacer 6 is situated in a middle area of the first section 4a, i.e., between the fastening of the S-shaped leaf spring 4 to the support frame 3 and the first curvature 4d, the compressible spacer with a first contact surface being displaceably guided on the first section 4a, and at its opposite end having a second contact surface on which the second section 4b of the S-shaped leaf spring 4 is (loosely) supported.

Depending on the design of the compressible spacer 6, in particular as a coil spring, a guide element for the spacer 6 may be provided in the area of the second section 4b. According to an optional feature, the spacer has a progressive spring characteristic curve. The S-shaped leaf spring 6 is preferably made of steel having a yield strength of greater than 500 MPa.

It is apparent from FIGS. 10 and 11 that only one S-shaped leaf spring 4, which is situated mirror-symmetrically with respect to or in the longitudinal center plane 7 of the chair, is provided.

FIGS. 3 and 4 show the S-shaped leaf spring 4 in a three-dimensional illustration, in which it is apparent that the first section 4a of the S-shaped leaf spring 4 has at least one recess 4f, in the form of an elongated hole, which extends in the longitudinal direction of the first section 4a for displacing the compressible spacer 6. In the illustrated exemplary embodiment the compressible spacer 6 is designed as a coil spring. However, as illustrated in FIGS. 1 and 2, it may also be formed from a Cellasto disk or a combination of a coil spring and a Cellasto disk.

The compressible spacer 6 is connected to an actuating element 8 for moving the compressible spacer 6 along the recess 4f and for detachably fixing the compressible spacer 6 in a desired position. In the simplest case this may be a screw-nut connection. In the exemplary embodiment according to FIGS. 5 and 6, however, the actuating element 8 is designed in such a way that a rotation of the actuating element 8 brings about a simultaneous displacement of the compressible spacer 6 along the recess 4f. For this purpose, the recess 4f is designed as an elongated hole with toothing 9, the actuating element 8 being in operative engagement with the toothing 9, so that a rotation of the actuating element 8 brings about a simultaneous displacement of the compressible spacer 6 along the recess 4f. In the illustrated embodiment, the toothing 9 is provided on a toothed track 10 that is installed on the bottom side of the section 4a, in the area of the recess 4f. However, it is also conceivable for the recess 4f that is provided in the section 4a to already have the toothing 9.

Ideally, the actuating element 8 and the elongated hole 4f provided with the toothing 9 engage with one another in the manner of self-locking lantern gear toothing. Thus, the actuating element 8, designed as a rotary handle, may remain in any position without additional measures. FIGS. 7a through 7h illustrate the engagement of the actuating element 8 with the toothing 9 for various positions of the actuating element or of the compressible spacer 6 connected thereto. It is also apparent from FIG. 6 and FIGS. 7a through 7h that on the side of the toothed track 10 facing away from the compressible spacer 6, the actuating element 8 has a rotatably fixedly connected first disk 8a whose diameter is larger than the width of the recess 4f. Two rollers or pins 8b, 8c that come into toothing engagement with the toothing 9 are situated on the first disk 8a. In turn, a second disk whose diameter is slightly smaller than the width of the recess 4f is fastened to the two pins 8b, 8c, and is guided in the recess 4f during the displacement of the compressible spacer 6. In turn, a third disk 8e that is displaceably guided on the top side of the first section 4a is provided on the second disk 8d. The compressible spacer 6 (in this case, the coil spring) is suitably mounted on this third disk 8e, for example by means of a mounting element 8f.

The S-shaped leaf spring 4 in interaction with the compressible spacer 6 is designed in such a way that bending into a tilted-back position of the chair is made possible. The seat 1 and the backrest 2 may be inclined further rearwardly and downwardly when the compressible spacer 6 is situated farther to the front, i.e., closer to the first curvature 4d, as is the case in FIG. 9 in comparison to FIG. 8. In an extension of the central column 3a of the support frame 3, an end stop 11 may optionally also be provided which limits the movement of the S-shaped leaf spring 4 under extremely high load, as shown in FIG. 9.

When the movement of the chair into the tilted-back position according to FIGS. 8 and 9 is initiated by a person sitting on the chair, this results not only in a lowering of the second section 4b about a virtual pivot point in the area of the first curvature 4d, but also in an increase in the angle between the seat 1 and the backrest 2, as for a conventional synchronous mechanism that is implemented by a swivel mechanism. The increase in the angle between the seat 1 and the backrest 2 is apparent in FIGS. 8 and 9 from the illustration of the backrest 2 with solid lines, in comparison to the dashed-line illustration of the backrest. The angle between the seat 1 and the backrest 2 may vary by approximately 5°, for example.

However, the S-shaped leaf spring 4 is designed to be deflectable not only with regard to bending into a tilted-back position according to FIGS. 8 and 9, but also preferably with regard to a rotation, so that the chair may be laterally tilted by the person sitting on the chair, as is apparent from FIGS. 10 and 11. Here as well, the position of the compressible spacer has an influence on the extent of the lateral tilting movement, so that a compressible spacer 6 situated farther to the front (FIGS. 2 and 9) allows a greater lateral tilting movement (see FIG. 11) than the compressible spacer 6 situated farther to the rear according to FIGS. 2, 9, and 12.

The rotatability of the first section 4a of the S-shaped leaf spring 4 about the longitudinal center axis 12 (FIGS. 5, 10, and 11), and thus the lateral tilting capability of the chair, is facilitated by the recess 4f which extends in the longitudinal direction of the first section 4a.