Chair

Abstract

This disclosure describes a chair having a base frame, a seat support, and a backrest support. The seat support is connected to the backrest support. The backrest support is rotatably connected to a rear part of the base frame such that a pivot axis is defined about which the backrest support is pivotable. The seat support is connected to a front part of the base frame by at least one four-joint coupling mechanism, whereby the seat support is moved on a defined movement path in the chair longitudinal direction during a pivoting movement of the backrest support.

Claims

1. A chair (1), comprising: a base frame (3); a seat support (4); and a backrest support (5); wherein the seat support (4) is connected to the backrest support (5), further, wherein the backrest support (5) is rotatably connected to a rear part (8) of the base frame (3), whereby a pivot axis (9) is defined about which the backrest support (5) is pivotable, and even further wherein the seat support (4) is connected to a front part (10) of the base frame (3) by a four-joint coupling mechanish (18), whereby the seat support (4) is moved on a defined movement path (20) in a chair longitudinal direction (7) during a pivoting movement of the backrest support(5), the defined movement path moving the seat support (4) forwardly and tilting a rear of the seat support downwardly, wherein the four-joint coupling mechanism comprises: a front motion link (24) and a rear motion link (25) rotatably mounted on the front part (10) of the base frame (3) to define positionally fixed front and rear bearing points (28, 29), whereas free ends (30, 31) of the motion links (24, 25) are rotatably connected to a movable coupling element (34) about respective front and rear articulation points (32, 33), which coupling element (34) has an arm (35) which extends forward as viewed in the chair longitudinal direction (7) and which is rotatably connected to the seat support (4), whereby an axis of rotation (38) of the seat support (4), which axis of rotation (38) is movable in the chair longitudinal direction (7) along the movement path (20), is defined.

2. The chair (1) according to claim 1, wherein the seat support is connected to the backrest support by a resilient connecting element.

3. The chair (1) according to claim 1, wherein the pivot axis (9) formed by connecting the backrest support (5) to the rear part (8) of the base frame (3) is positionally fixed.

4. The chair (1) according to claim 1, wherein a connecting element (6) connects the seat support (4) to the backrest support (5) such that a movement of one of the two supports induces a non-identical consequential movement of the respective other support.

5. The chair (1) according to claim 1, having at least one spring element (23) which connects the base frame (3) to the seat support (4).

6. The chair (1) according to claim 1, wherein the motion links (24, 25) perform a forward pivoting movement (39) about their respective bearing points (28, 29) during a rearward pivoting movement of the backrest support (5).

7. The chair (1) according to claim 6, wherein the four joint coupling mechanism (18) is designed such that, during a rearward pivoting movement of the backrest support (5), the axis of rotation (38) of the seat support (4) moves forward substantially rectilinearly.

8. The chair (1) according to claim 7, wherein the movement path (20) is inclined with respect to the horizontal.

9. The chair according to claim 1, wherein: the bearing points (28, 29) are spaced apart vertically from one another with the front bearing point (28) situated below the rear bearing point (29).

10. The chair according to claim 9, wherein: the articulation points (32, 33) arranged at the free ends (30, 31) are spaced apart vertically from one another during all points of travel, with the front articulation point (32) situated above the rear articulation point (33).

11. The chair according to claim 1, wherein: the axis of rotation (38) of the seat support (4) does not lie on an imaginary straight line formed by the two articulation points (32, 33).

12. The chair according to claim 1, wherein: the axis of rotation (38) lies approximately at the level of the rear articulation point (33) of the rear motion link (25), at least during almost the entire movement of the seat support (4) along the movement path (20).

13. The chair according to claim 1, wherein: when the backrest support (5) is not subjected to load, the two motion links (24, 25) are arranged so as to be tilted rearward, and when the backrest support has been pivoted rearward to the greatest possible extent, the two motion links (24, 25) are arranged so as to be tilted forward.

14. The chair of claim 1, wherein: the movement path (20) of the axis of rotation (38) of the seat support (4) assumes an end profile which deviates, from an initially substantially rectilinear profile with uniform upward inclination in the forward direction, to abruptly rise steeply when the backrest support reaches the greatest possible extent of rearward pivot.

15. The chair of claim 14, wherein the axis of rotation (38) of the seat support (4) changes relative position with respect to the rear articulation point (33) of the rear motion link (25) in an end position of the two motion links (24, 25) such that the axis of rotation (38) of the seat support 4 is situated above the rear articulation point 33.

16. The chair of claim 15, wherein, the axis of rotation (38) is disposed above the front articulation point (32) of the front motion link (24) when the backrest support has been pivoted rearward to the greatest possible extent.

17. A chair (1), comprising: a base frame (3) having a front part (10) and a rear part (8); a seat support (4); and a backrest support (5); wherein the seat support (4) is connected to the backrest support (5) by a resilient connecting element such that a movement of one of the two supports induces a non-identical consequential movement of the respective other support, the backrest support (5) being rotatably connected to the rear part (8) of the base frame (3) at a pivot axis (9), the seat support (4) being connected to a front part (10) of the base frame (3) by a four-joint coupling mechanism (18) that includes a front motion link (24) and a rear motion link (25) rotatably mounted on the front part (10) of the base frame (3) to define positionally fixed front and rear bearing points (28, 29), free ends (30, 31) of the motion links (24, 25) being rotatably connected to a movable coupling element (34) about respective front and rear articulation points (32, 33), the coupling element (34) having an arm (35) which extends forward as viewed in the chair longitudinal direction (7) and which is rotatably connected to the seat support (4) at an axis of rotation (38) for the seat support (4), the axis of rotation (38) being movable in the chair longitudinal direction (7) along a movement path (20) during a pivoting movement of the backrest support(5), so the seat support (4) moves forwardly and a rear of the seat support tilts downwardly.

18. The chair according to claim 17 wherein: the bearing points (28, 29) are spaced apart vertically from one another with the front bearing point (28) situated below the rear bearing point (29), the articulation points (32, 33) arranged at the free ends (30, 31) are spaced apart vertically from one another during all points of travel, with the front articulation point (32) situated above the rear articulation point (33), and when the backrest support (5) is not subjected to load, the two motion links (24, 25) are arranged so as to be tilted rearward, and when the backrest support has been pivoted rearward to the greatest possible extent, the two motion links (24, 25) are arranged so as to be tilted forward.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An exemplary embodiment will be discussed in more detail below on the basis of the drawings, in which:

(2) FIG. 1 shows a rear perspective of the chair;

(3) FIG. 2 shows a rear perspective of the base frame;

(4) FIG. 3 shows a cross sectional view of the chair through a central plane along the longitudinal direction.

(5) FIG. 4 schematically shows a partial section of the chair in longitudinal section in the normal upright position,

(6) FIG. 5 shows a four-joint coupling mechanism, designed as a double motion link mechanism, in an initial position,

(7) FIG. 6 shows the four-joint coupling mechanism from FIG. 5 in a first intermediate position,

(8) FIG. 7 shows the four-joint coupling mechanism from FIG. 5 in a second intermediate position,

(9) FIG. 8 shows the four-joint coupling mechanism from FIG. 5 in an end position.

DETAILED DESCRIPTION

(10) Here, all of the figures show the invention not true to scale but merely schematically, and only with the major constituent parts thereof. Here, the same reference signs are used to denote elements of identical or similar function.

(11) An office chair 1 according to the invention comprises, as illustrated in FIG. 1, a base frame 3 mounted on a chair column 2, a seat support 4, and a backrest support 5. As seen in FIGS. 1 and 2, the base frame 3 includes a rear part 8 that may branch into a pair of chair arms 8a, 8b. The front part 10 of the base frame 3 may include a pair of extensions 10a, 10b.

(12) As best seen in FIGS. 3 and 4, the seat support 4 is connected to the backrest support 5 byway of a curved resilient connecting element 6. The backrest support 5 is rotatably connected to a rear part 8 of the base frame 3 as viewed in the chair longitudinal direction 7. The rear part 8 provides a positionally fixed pivot axis 9 formed between the backrest support 5 and the rear part 8 of the support frame 3, about which the backrest support 5 can be pivoted. The rear part 8 of the base frame 3 extends rearward and upward proceeding from a front part 10 of the base frame 3, which has the receiving opening 11 for the chair column 2.

(13) The pivot axis 9 is thus situated a considerable distance above the seat support 4, in the region of the lower half of the backrest support 5. The pivot axis 9 runs perpendicular to the chair longitudinal direction 7.

(14) The seat support 4 comprises a lower shell 13 and an upper shell 14. The upper shell 14 is connected to the lower shell 13 at the front end 15 of the seat support 4 and at the rear end 16 of the seat support 4. Between the lower shell 13 and upper shell 14 there is a receiving chamber 17. The lower shell 13 may extend as a direct elongation of the connecting element 6 and serves for the connection of the seat support 4 to the base frame 3. The upper shell 14 may serve for supporting a seat cushion.

(15) Preferably, the seat support 4 is connected to each extension 10a, 10b of the front part 10 of the base frame 3 as viewed in the chair longitudinal direction 7 byway of a four-joint coupling mechanism which is configured as a double motion link mechanism 18. In this way, the seat support 4 is moved on a defined movement path 20 (see FIG. 5) (forward and upward) in the chair longitudinal direction 7 when the backrest support 5 is pivoted rearward and downward in the pivoting direction 19. The double motion link mechanism 18 may extend through an opening 21 formed in the lower shell 13.

(16) The entire pivoting mechanism may be, as regards the kinematic arrangement thereof, of mirror-symmetrical construction about its central longitudinal plane. In this respect, in this description, it should be understood that structural elements can be provided in pairwise fashion at both sides. For example, a first double motion link mechanism 18 may be assigned to the right-hand side of the chair 1 through a first extension 10a, and a second double motion link mechanism may be assigned to the left-hand side of the chair 1 through a second extension 10b; the backrest support 5 can have a twofold articulated connection to the base frame 3 etc. (see FIGS. 1 and 2), wherein FIGS. 3 and 4 illustrate only the structural elements assigned to one half of the chair.

(17) The connecting element 6 connects the seat support 4 to the backrest support 5 such that a movement of one of the two parts induces a non-identical consequential movement of the respective other part. In the exemplary embodiment shown here, the seat support 4 and backrest support 5 form a structural unit, but are movable relative to one another rather than being rigidly connected to one another. The seat support 4 and the backrest support 5 in this embodiment are directly linked via the elastic connecting element 6. In other embodiments a rotary joint, hinge, or pivot joint may be used to connect the seat support 4 to the backrest support 5.

(18) Furthermore, a spring mechanism having at least one spring element can be provided. The spring mechanism can include tension springs 23 which connect the base frame 3 to the seat support 4. FIG. 4 symbolically illustrates the tension spring 23 being arranged between the front part 10 of the base frame 3 and the front part 15 of the seat support 4. The spring mechanism serves to assist or influence the pivoting resistance of the backrest support 5 and/or to prevent the backrest support 5 from tilting rearward in uncontrolled fashion, and for reliably returning the backrest support 5 from a pivoted position into the initial position when the user no longer exerts load on the backrest.

(19) The double motion link mechanism 18 connected to the base frame 3 projects through the opening 21 in the lower shell 13 into the receiving chamber 17 between the lower shell 13 and upper shell 14 of the seat support 4. As best seen in FIGS. 5-8, the two motion links 24, 25 of the double motion link mechanism 18 are in this case rotatably mounted by way of their bearing ends 26, 27 on the front part 10 of the base frame 3, with the formation of spaced-apart, positionally fixed bearing points 28, 29. The free ends 30, 31 of the two motion links 24, 25 are rotatably connected to a movable coupling element 34 at spaced-apart articulation points 32, 33. The coupling element 34 has an elongation in the form of an arm 35 which extends forward as viewed in the chair longitudinal direction 7 and which is rotatably connected to the seat support 4. In the illustrated embodiment, the front end 36 of the arm 35 is rotatably connected to an actuation section 37 of the seat support 4. The actuation section 37 may be rigidly connected to the lower shell 13 of the seat support 4 to project upwardly away from the lower shell 13. Connection between the actuation section 37 and the front end 36 defines an axis of rotation 38 of the seat support 4, which axis of rotation 38 is movable in the chair longitudinal direction 7. In this case, like all the other axes of rotation and pivot axes, the axis of rotation 38 runs perpendicular to the chair longitudinal direction 7.

(20) To realize a particularly stable construction, the coupling element 34 maybe manufactured from two congruent components which are arranged on the articulation points 32, 33 so as to be spaced apart from one another by means of spacers and which receive the two motion links 24, 25 between them.

(21) By means of the arrangement of the coupling elements 34 of the double motion link mechanisms 18 arranged to the right and to the left on the base frame 3, and the configuration thereof, the synchronous movement of the seat support 4 can be individually adapted to the demands placed on the office chair 1. For example, by changing the lengths of the coupling elements 34 and/or the angular positions thereof, it is possible to define the extent to which the seat support 4 is tilted during a pivoting movement of the backrest support 5, and/or the extent to which the seat support 4 is displaced horizontally forward relative to the base frame 3 as viewed in the chair longitudinal direction 7.

(22) In one embodiment, the positionally fixed bearing points 28, 29 of the double motion link mechanism 18 are spaced apart vertically from one another. The front bearing point 28 is situated below the rear bearing point 29. The two articulation points 32, 33 arranged at the free ends 30, 31 are likewise spaced apart vertically from one another. The front articulation point 32 is situated above the rear articulation point 33 in at least the initial position shown in FIG. 5, and in some embodiments, at all positions during travel.

(23) In one embodiment, the two motion links 24, 25 are of different lengths. The front motion link 24 may be longer than the rear motion link 25.

(24) In one embodiment, the axis of rotation 38 of the seat support 4 does not lie on the imaginary straight line formed by the two articulation points 32, 33. Instead, the axis of rotation 38 lies below said straight line, specifically approximately at the level of the articulation point 33 of the rear motion link 25, at least during almost the entire movement of the seat support 4 on the movement path 20.

(25) During a pivoting movement of the backrest support 5 in the rearward pivoting direction 19, the two motion links 24, 25 of the double motion link mechanism 18 perform a forward pivoting movement about their bearing points 28, 29, as indicated in FIG. 5 by arrow 39.

(26) In the initial position shown in FIG. 5, in which the backrest support 5 is not subjected to load, that is to say is not pivoted rearward, the two motion links 24, 25 are arranged so as to be tilted rearward. The articulation points 32, 33 of the motion links 24, 25 are situated behind the bearing points 28, 29 of the respective motion link 24, 25. The articulation point 32 of the front motion link 24 is still situated in front of the bearing point 29 of the rear motion link 25.

(27) In the end position shown in FIG. 8, in which the backrest support 5 has been pivoted rearward to the greatest possible extent, the two motion links 24, 25 are arranged so as to be tilted forward. The articulation points 32, 33 of the motion links 24, 25 are situated in front of the bearing points 28, 29 of the respective motion link 24, 25. The articulation point 33 of the rear motion link 25 is still situated in front of the bearing point 28 of the front motion link 24.

(28) In all positions of the double motion link mechanism 18, the articulation point 32 of the front motion link 24 can be situated above the articulation point 33 of the rear motion link 25.

(29) The double motion link mechanism 18 is designed such that, during a rearward pivoting movement of the backrest support 5, the axis of rotation 38 of the seat support 4 moves forward on a substantially rectilinear movement path 20.

(30) During the forward pivoting movement of the motion links 24, 25, the articulation points 32, 33 pass over the bearing points 28, 29 of the respective motion link 24, 25. The coupling element 34 and thus the axis of rotation 38 of the seat support 4 move substantially on a straight line for a majority of the movement path 20. The relative position of the axis of rotation 38 of the seat support 4 with respect to the articulation point 33 of the rear motion link 25 remains virtually unchanged.

(31) The substantially rectilinear movement path 20 may be inclined with respect to the horizontal and runs with a uniform upward inclination in the forward chair longitudinal direction 7, as shown by way of the intermediate positions in FIGS. 6 and 7. In this case, the movement path 20 encloses an angle of approximately 13 degrees with the horizontal.

(32) A pivoting movement of the backrest support 5 from the initial position into the rearwardly pivoted position is associated with an immediate lifting movement of the seat support 4 with a slight forward inclination. The seat support 4 is thus driven along synchronously in a defined relationship with respect to the backrest support 5, with a slight tilting of the seat surface. This gives rise to the desired synchronous effect in which the angle of the seat support 4 relative to the backrest support 5 changes.

(33) The weight of the user has a direct effect on the pivoting resistance of the backrest support 5 which is perceptible to the user. A user of low weight has to overcome a considerably lower pivoting resistance when pivoting the backrest support 5 than a heavy user. This has the effect that, subjectively, every user experiences the same perceptible resistance when pivoting the backrest support 5.

(34) In the illustrated embodiment, the double motion link mechanism 18 is designed such that, shortly before the end position of the two motion links 24, 25 illustrated in FIG. 8 is reached, the movement path 20 of the axis of rotation 38 of the seat support 4 assumes an end profile which deviates from its substantially rectilinear profile with uniform upward inclination in the forward direction, and abruptly rises steeply. Said range of the movement path is denoted in FIG. 8 by arrow 40. In this way, the user experiences a type of braking effect, as they feel an increased resistance. The movement of the seat support 4 induced by the pivoting movement of the backrest support 5 is braked directly before the end position is reached. The axis of rotation 38 of the seat support 4 changes its relative position with respect to the articulation point 33 of the rear motion link 25. In the end position of the two motion links 24, 25, the axis of rotation 38 of the seat support 4 is now situated above the articulation point 33 of the rear motion link 25, and even above the articulation point 32 of the front motion link 24.

(35) As used herein, a four-joint coupling mechanism is to be understood to mean a construction corresponding to a four-bar coupling gear unit which is, logically, composed of four interconnected elements, wherein the first gear element is formed by the base frame of the chair. The three further elements correspond to the input element, the output element, and the coupling element of a coupling gear, wherein, in the present case, the four-joint coupling mechanism does not perform the function of a gear unit but serves solely for the guidance of the seat support, which is connected to the coupling element, relative to the base frame, such that neither an input element nor an output element in the sense of a gear unit is provided.

(36) The invention is not restricted to the exemplary embodiment. All of the features presented in the description, in the following claims and in the drawings may be essential to the invention both individually and in any desired combination with one another.

LIST OF REFERENCE NUMERALS

(37) 1 Office chair

(38) 2 Chair column

(39) 3 Base frame

(40) 4 Seat support

(41) 5 Backrest support

(42) 6 Connecting element

(43) 7 Chair longitudinal direction

(44) 8 Rear part of the base frame

(45) 8a,8b Chair arm

(46) 9 Pivot axis of the backrest support

(47) 10 Front part of the base frame

(48) 10a, 10b Extension

(49) 11 Receiving opening

(50) 12 (unused)

(51) 13 Lower shell

(52) 14 Upper shell

(53) 15 Front end of the seat support

(54) 16 Rear end of the seat support

(55) 17 Receiving chamber

(56) 18 Double motion link mechanism

(57) 19 Pivoting direction

(58) 20 Movement path

(59) 21 Opening

(60) 22 (unused)

(61) 23 Tension spring

(62) 24 Front motion link

(63) 25 Rear motion link

(64) 26 Bearing end of the front motion link

(65) 27 Bearing end of the rear motion link

(66) 28 Bearing point of the front motion link

(67) 29 Bearing point of the rear motion link

(68) 30 Free end of the front motion link

(69) 31 Free end of the rear motion link

(70) 32 Articulation point of the front motion link

(71) 33 Articulation point of the rear motion link

(72) 34 Coupling element

(73) 35 Arm

(74) 36 Free end of the arm

(75) 37 Actuation section

(76) 38 Axis of rotation of the seat support

(77) 39 Pivoting movement

(78) 40 End region of the movement path