Patent Publication Number: US-10772427-B2

Title: Seating furniture

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a seating furniture comprising a tilt mechanism as well as a tilt mechanism for such a seating furniture. 
     Seating furniture typically comprises a seat having a seat surface and a pedestal. A seat surface tiltable relative to the horizontal enables an active-dynamic and thus ergonomic sitting for the user. F or this purpose, it is known to arrange a so-called tilt mechanism between the pedestal and the seat, which is designed to allows the seat surface of the seat to tilt relative to the horizontal in one or more directions. 
     EP 1 584 266 B1 discloses such a tilt mechanism which allows the seat surface to tilt relative to the horizontal in both a front/rear direction of the seat surface and a right/left direction of the seat surface. For this, the tilt mechanism comprises a pressure plate having a first conicity in the front/rear direction of the seat surface by which the seat can tilt in the front/rear direction, and a second conicity in the right/left direction of the seat surface by which the seat can tilt in the right/left direction. 
     WO 2016/074784 A1 describes a tilt mechanism for an office chair which comprises two bearing parts arranged movable relative to each other and having bearing shells being curved correspondingly to each other for mutual bearing, which are tiltable relative to each other in a predetermined angular range by a shift of weight of a user on the seat surface. 
     SUMMARY OF THE INVENTION 
     It is the object of the invention to provide a seating furniture having a simply designed and smooth-running tilt mechanism. 
     This object is achieved by the teaching of the independent claims. Some advantageous configurations of the invention are the subject of the dependent claims. 
     The seating furniture according to the invention comprises a seat having a seat surface, a pedestal and a tilt mechanism. The tilt mechanism is arranged between the pedestal and the seat and is designed to allow the seat surface of the seat to tilt relative to the horizontal. The tilt mechanism comprises a lower bearing block mounted on the pedestal and an upper bearing block fixedly connected to the seat. According to the invention, the seating furniture is characterized in that the lower bearing block has a convex curved lower bearing surface on its upper side facing towards the upper bearing block, and the upper bearing block has a concave curved upper bearing surface on its lower side facing towards the lower bearing block, wherein the lower bearing surface of the lower bearing block and the upper bearing surface of the upper bearing block have substantially identical radii of curvature, and wherein the upper bearing block is moveable relative to the lower bearing block along the upper bearing surface. 
     The seating furniture of the invention having the specifically designed tilt mechanism enables an ergonomic sitting for the user. 
     The tilt mechanism of the inventive seating furniture is designed simple and with few components. By this, the weight of the tilt mechanism and the entire seating furniture can be reduced. 
     By moving the two curved bearing surfaces of the two bearing blocks relative to each other, a tilting of the seat surface is smooth-running and thus comfortable for the user. Also, the moving of the two curved bearing surfaces of the two bearing blocks relative to each other is relatively low-wear in comparison to conventional structures of the tilt mechanism so that the tilt mechanism can have a long service life. 
     The seating furniture is preferably an office chair or a student chair. In addition, the seating furniture is preferably designed as a swivel chair. The seat has a seat surface and preferably also a backrest. The seat surface and backrest can then be designed as a common component or as two separately formed, interconnected components. 
     The lower bearing block of the tilt mechanism is mounted on the pedestal, i.e. immovable connected with it. The connection can be made detachable or permanent. The upper bearing block of the tilt mechanism is directly or indirectly (e.g. via a seat carrier) fixed, i.e. immovably connected to the seat. The connection can be made detachable or permanent. 
     The seat surface of the seat defines in particular a front/rear direction and a right/left direction. The tilt mechanism allows the seat surface to tilt relative to the horizontal in at least one direction (e.g. front/rear direction of the seat surface), preferably in several directions (e.g. in both the front/rear direction and the right/left direction of the seat surface). The tilting of the seat surface in several directions can preferably be made continuously in the circumferential direction (e.g. gyroscopic motion), alternatively only in different discrete directions. 
     In an advantageous configuration of the invention, the tilt mechanism further comprises an intermediate element which is arranged between the lower bearing surface and the upper bearing surface. This intermediate element preferably reduces a sliding resistance between the lower and upper bearing surfaces in a relative movement between the lower and upper bearing blocks. With such an intermediate element, tilting of the seat surface can be made very smooth-running and quiet. In addition, such an intermediate element can extend the service life of the tilt mechanism. 
     In an advantageous configuration of the invention, the intermediate element of the tilt mechanism is placed on the lower bearing surface (e.g. unmounted set or fixed on the lower bearing surface) and has a reduced sliding resistance on its upper side facing towards the upper bearing surface. Alternatively, the intermediate element may also be provided on the upper bearing surface and have a reduced sliding resistance on its lower side facing towards the lower bearing surface. 
     Preferably, the intermediate element of the tilt mechanism is curved convexly on its upper side and curved concavely on its lower side facing towards the lower bearing surface. Preferably, the radii of curvature of the upper and lower sides of the intermediate element coincide with the radii of curvature of the upper and lower bearing surfaces of the bearing blocks. 
     In an advantageous configuration of the invention, the pedestal of the seating furniture comprises a pillar having a gas spring, wherein the gas spring is operable by a user by means of an operating. In this configuration, the intermediate element of the tilt mechanism preferably comprises a stop for a movement of the operating lever or forms such a stop. In other configurations of the invention, the pedestal of the seating furniture has a simple pillar, a threaded spindle, etc. 
     In another advantageous configuration of the invention, the tilt mechanism further comprises a housing in which the lower bearing block and the upper bearing block are at least partially contained. The housing protects the components of the tilt mechanism against dirt and damage and protects the user against catching between the movable parts of the tilt mechanism. 
     Preferably, the housing of the tilt mechanism is fixedly connected to the upper bearing block and movable relative to the lower bearing block. 
     In an advantageous configuration of the invention, the pedestal of the seating furniture comprises a pillar having a gas spring. In this configuration, the housing of the tilt mechanism preferably has a housing opening for passing an operating lever for the gas spring of the pillar. In other configurations of the invention, the pedestal of the seating furniture has a simple pillar, a threaded spindle, etc. 
     In another advantageous configuration of the invention, the tilt mechanism further comprises at least one elastic element which generates a spring effect opposing the relative movement between the lower and upper bearing blocks. The elastic element dampens the tilting movement of the seat surface in the various directions and supports a return of the seat surface into the neutral position. The elastic element also enables a stop-free tilt limit and thus an elimination of impact noises at intense tiltings of the seat surface. The elastic element is preferably a spring block, i.e. a block made of an elastic material. Thus, the spring effect can be achieved by compressing the elastic element, and the stop-free tilt limit can be achieved by the maximum compression of the elastic element. The at least one elastic element is preferably designed as an annular spring block or as a plurality of annularly arranged spring blocks. 
     In an advantageous configuration of the invention, this at least one elastic element of the tilt mechanism is arranged between the lower bearing block and the housing. Preferably, the lower bearing block has a circumferential projection, and the elastic element is arranged between a lower side of this circumferential projection facing away from the upper bearing block and a lower housing wall. 
     In another advantageous configuration of the invention, the tilt mechanism enables different maximum tilt angles in various tilt directions. For example, the tilt mechanism allows the seating surface of the seat to tilt relative to the horizontal in the front/rear direction of the seat surface by a maximum of about 8 degrees and to tilt relative to the horizontal in the right/left direction of the seat surface by a maximum of about 3.5 degrees. 
     Subject-matter of the present invention is also a tilt mechanism itself which can be arranged between a pedestal and a seat of a seating furniture and is designed to allow the seat surface of the seat to tilt relative to the horizontal in several directions. The tilt mechanism of the invention is configured as above in connection with the seating furniture of the invention and gives the same advantages. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The above and other advantages, features and application possibilities of the invention will become more apparent from the following description of various embodiments with reference to the accompanying drawings, in which, mostly schematically: 
         FIG. 1  is a perspective view of a seating furniture according to an embodiment of the invention; and 
         FIG. 2  is a sectional view of a tilt mechanism according to an embodiment of the invention. 
     
    
    
     DESCRIPTION OF THE INVENTION 
       FIG. 1  exemplarily shows an office or school chair as a seating furniture  10  of the invention. 
     The seating furniture  10  comprises a seat  12  having a seat surface  12   a  and a backrest  12   b . In this embodiment, the seat surface  12   a  and the backrest  12   b  are designed in the form of a common seat shell; In other embodiments of the invention, the seat surface  12   a  and the backrest  12   b  may also be designed as separate components connected to each other. In this embodiment, the seat  12  is made of a plastic material; in other embodiments of the invention, other materials or combinations of materials may also be used. 
     The seat  12  is mounted on a seat carrier  13  and supported on a pedestal  14 . In this embodiment, the pedestal  14  comprises a pedestal base  16  having a plurality of arms and casters  18 . In the middle of the pedestal base  16 , the pedestal  14  has a pillar  20 . In this embodiment, the pillar  20  is equipped with a piston  20   a  and a gas spring  20   b  so that the seating furniture  10  is adjustable in height. 
     A tilt mechanism  24  is provided between the pedestal  14  and the seat  12  or the seat carrier  13 . This tilt mechanism  24  allows the seating surface  12   a  of the seat  12  tilt relative to the horizontal in a plurality of directions, in particular in a front/rear direction of the seat surface  12   a  and a right/left direction of the seat surface  12   a  (either continuously in the circumferential direction or in discrete directions) so that an ergonomic sitting can be achieved for a user of the seat furniture  10 . 
     The structure and operation of such a tilt mechanism are explained below in more details referring to a preferred embodiment of the invention with reference to  FIG. 2 . 
       FIG. 2  shows an upper end of the pillar  20  of the pedestal  14 , which is equipped with a gas spring, and an inner end of a corresponding operating lever  22  for the gas spring, with which a user can operate the gas spring to change the length of the pillar  20  and thus the height of the seat surface  12   a  as he wishes. 
     The tilt mechanism  24  comprises a lower bearing block  26  made of metal, for example. This lower bearing block  26  is mounted on the upper end of the pillar  20 , for example placed by press-fitting. On its upper side facing towards the seating surface  12   a , the lower bearing block  26  has a central projection  27  which is provided with a convex curved lower bearing surface  28 . This lower bearing surface  28  is designed particularly as a spherical shell section with a predetermined radius of curvature. 
     The tilt mechanism  24  further comprises an upper bearing block  30  made of metal, for example. On this upper bearing block  30 , the seat carrier  13  and thus the seat  12  are mounted, for example by means of a screw connection. At its lower side facing towards the lower bearing block  26 , the upper bearing block  30  is formed with a central recess  31  which is provided with a concave curved upper bearing surface  32 . This upper bearing surface  32  is designed particularly as a spherical shell section with a predetermined radius of curvature which is substantially identical to the radius of curvature of the lower bearing surface  28  of the lower bearing block  26 . The upper bearing surface  32  is preferably formed as a full-surface bearing surface (in contrast to annular bearing surfaces, for example). 
     As shown in  FIG. 2 , the lower and upper bearing surfaces  28 ,  32  are slightly spaced apart from each other. In this preferred embodiment, an intermediate member  34  in the form of a sliding cap is inserted between the lower bearing surface  28  at the lower bearing block  26  and the upper bearing surface  32  at the upper bearing block  30 . 
     In the embodiment of  FIG. 2 , the intermediate element  34  is placed on the lower bearing surface  28  of the lower bearing block  26 . The intermediate element is curved convexly on its upper side facing towards the upper bearing surface  32  and curved concavely on its lower side facing towards the lower bearing surface  28 . The radii of curvature of the intermediate element  34  are substantially identical to the radii of curvature of the bearing surfaces  28 ,  32 . The upper side of the intermediate element  34  preferably forms an at least almost full-surface bearing surface. 
     The central projection  27  of the lower bearing block  26  is formed with at least one recess  38 . The intermediate element  34  is formed with at least one projection  36  which can engage into the at least one recess  38 , on its lower side. Thus, the intermediate element  34  can be fixed by press-fitting to the projection  27  of the lower bearing block  26 . Alternatively or additionally, for example, an adhesive bond may be used. Alternatively, the intermediate element  34  may also be placed only loosely on the lower bearing surface  28  or loosely placed on the lower bearing surface  28  and then glued to this. 
     On its upper side, the intermediate element  34  has a reduced sliding resistance. That is, the sliding resistance between the upper side of the intermediate member  34  and the upper bearing surface  32  is reduced compared to the sliding resistance between the upper bearing surface  32  and the lower bearing surface  28 . For this purpose, the intermediate element  34  is preferably made of a plastic material; in addition, the upper side of the intermediate element  34  may be specifically prepared and/or coated. 
     The projection  36  of the intermediate member  34  projecting into the recess  38  of the projection  27  of the lower bearing block  26  serves, as illustrated in  FIG. 2 , at the same time as a stop for the inner end of the operating lever  22  for the gas spring of the pillar  20 . Thus, the intermediate element  34  limits the route of the operating lever  22  and prevents its abutment against the lower bearing block  26 . In this way, noises caused by the abutment of the operating lever  22  with the lower bearing block  26 , which are usually both made of metal, can be prevented. 
     The lower bearing block  26  and the upper bearing block  30  are surrounded by a housing  40 . The housing  40  is made of metal or plastic, for example. The housing  40  is part of the tilt mechanism  24  and mounted on the upper bearing block  30 . 
     In this embodiment, the housing  40  has a housing opening  44  for passing the operating lever  22  for the gas spring. 
     The lower bearing block  26  comprises a circumferential projection  43  and the housing  40  comprises a lower housing wall  45  as the lower boundary of the housing  40 . The tilt mechanism  24  further comprises at least one elastic element  42 , which is formed as an annular spring block made of an elastic material, in this embodiment. This elastic element  42  is positioned between the lower side of the circumferential projection  43  of the lower bearing block  26  and the lower housing wall  45  of the housing  40 . 
     When the user moves his weight on the seating surface, the upper bearing block  30  of the tilt mechanism  24 , which is fixedly connected to the seating surface  12   a  via the seat carrier  13 , moves along its upper bearing surface  32  relative to the intermediate element  34  and thus relative to the lower bearing block  26 . By this, the seat surface  12   a  tilts relative to the horizontal. 
     Due to the intermediate element  34  between the two corresponding bearing surfaces  28 ,  32 , this tilting movement is smooth-running and quiet-running. 
     In other embodiments, it is also possible to omit the intermediate element  34  between the bearing surfaces  28 ,  32  of the two bearing blocks  26 ,  30 . In this case, at least one of the two bearing surfaces  28 ,  32  is preferably treated or coated in order to reduce a sliding resistance between the two bearing surfaces  28 ,  32 . 
     During this tilting movement, the housing  40  of the tilt mechanism  24 , which is fixedly connected to the upper bearing block  30 , is also moved relative to the lower bearing block  26 . As consequence, the elastic element  42  is compressed on one side and thus generates a spring force opposing the tilt. The maximum tilt is given by the maximum compression of the elastic element  42 . An abutment of the housing  40  against the lower bearing block  26  is also prevented by the elastic member  42 . In addition, the elastic element  42  supports a return of the seat surface  12   a  to the neutral position. 
     The elastic element  42  may also have different elastic properties along its circumference, in particular different maximum degrees of compression. Thus, it is easily possible that the seat surface  12   a  has different maximum tilt angles in various tilt directions. For example, the tilt mechanism  24  allows the seating surface  12   a  of the seat  12  to tilt in the front/rear direction of the seat surface  12   a  by about 8 degrees at maximum relative to the horizontal, tilt in the right/left direction of the seat surface  12   a  by about 3.5 degrees at maximum relative to the horizontal. 
     LIST OF REFERENCE SIGNS 
       10  seating furniture 
       12  seat 
       12   a  seat surface 
       12   b  backrest 
       13  seat carrier 
       14  pedestal 
       16  pedestal base 
       18  casters 
       20  pillar, esp. having a gas spring 
       22  operating lever, esp. gas spring lever 
       24  tilt mechanism 
       26  lower bearing block 
       27  projection 
       28  convex curved lower bearing surface 
       30  upper bearing block 
       31  recess 
       32  concave curved upper bearing surface 
       34  intermediate element 
       36  projection 
       38  recess 
       40  housing 
       42  elastic element, esp. spring block 
       43  circumferential projection 
       44  housing opening 
       45  lower housing wall