Patent Publication Number: US-6209963-B1

Title: Variable configuration mounting arrangement for a chair back support member

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates to chairs, and more particularly to an arrangement for mounting a chair back support member to the underside of a chair seat. 
     Typical chair construction involves mounting a chair seat and chair back to a chair control mechanism, which in turn is supported above the floor by a chair base. The chair control mechanism is mounted to a support column associated with the base, which typically is in the form of an adjustable height gas cylinder for varying the elevation of the seat above the floor. The chair back is typically mounted to the upper end of a chair back support. The chair back support defines a lower end which is mounted such that the chair back is spaced above the seat and located toward the rearward end of the seat. The lower end of the chair back support may be mounted to the underside of the seat, or mounted to the chair control mechanism. Mounting of the chair back support to the seat or the chair control mechanism may be a fixed-type mounting in which the position of the chair back relative to the seat is fixed, or such mounting may include provisions for altering the angle of the back relative to the seat. 
     Chair back supports are commonly in the form of a J-bar, which defines an upper end to which the chair back is mounted, and a lower end adapted for mounting either to the underside of the seat or to the chair control mechanism. J-bars are commonly formed of bent bar stock, and the width and thickness of the J-bar typically varies according to the chair design and different user or manufacturer requirements. These variations in the width and thickness of the J-bar present difficulties when the J-bar is to be mounted to the chair control mechanism. In the past, it has been known to provide chair control mechanisms with a different J-bar mounting area for each width and thickness of J-bar available. This requires separate tooling for each such J-bar mounting area and different part numbers for each version of the same chair control mechanism which has a differently configured J-bar mounting area. 
     It is an object of the present invention to provide a mounting arrangement for a chair back support member which is capable of accommodating chair back supports of varying dimensions. It is another object of the invention to provide such a mounting arrangement which is well suited for use in mounting differently configured chair back supports to a chair control mechanism. Yet another object of the invention is to provide such a mounting arrangement which entails relatively minor alterations in the configuration of a mounting area associated with a chair control mechanism while accommodating differently configured chair back support members. Yet another object of the invention is to provide such a mounting system which is relatively simple in its configuration and components and which is easily adapted to use with chair back support members of different configurations. 
     The invention generally contemplates a mounting system for a chair back support member, for mounting a chair back support member to a chair seat or to a chair control mechanism. The mounting system of the invention is capable of mounting chair back supports of varying width and thickness. In a preferred form, the mounting system is interconnected with the chair control mechanism, such that the chair control mechanism and mounting system are together secured to the underside of the seat. 
     In one form of the invention, the mounting system is provided on a receiver which is secured to seat support structure associated with the chair control mechanism. The receiver includes an opening through which the chair back mounting member extends, and an engagement arrangement located inwardly of the opening, for engaging the chair back support member with the receiver. The engagement arrangement may either be a fixed-type arrangement in which the position of the chair back is not adjustable relative to the seat, or an adjustable arrangement in which the position of the chair back relative to the seat can be adjusted. The invention contemplates positioning one of a series of inserts within the opening in the receiver, and each insert defines a passage configured to receive a chair back mounting member having a specific configuration. The passage in each insert is configured according to the specific dimensions of one type of chair back mounting member, such that each insert has a differently configured passage according to the number of different chair back mounting members which may be employed in connection with the chair control mechanism. In this manner, the same chair control mechanism and receiver is used for each available chair back mounting member, and it is only necessary to position the desired insert within the opening in the receiver according to the configuration of the chair back mounting member to be used for a particular chair. 
     In another form, the invention contemplates a mounting area for a chair back support member which includes a pair of spaced sidewalls together with an engagement wall which extends between the pair of spaced sidewalls. Inwardly extending protrusions are provided on each of the sidewalls. The sidewalls, engagement wall and protrusions are configured so as to define a mounting area adapted to receive the lower end of a chair back support member having a maximum width and thickness. When a chair back support member having a lesser width and/or thickness is to be used with the chair control mechanism, a set of inserts are engageable within the protrusions to alter the configuration of the mounting area to accommodate the lesser thickness and/or width of the chair back support member. Each set of inserts is specifically configured for a particular width and thickness of chair back support member which is adapted to be used in combination with the chair control mechanism. With this arrangement, the same basic structure of the chair control mechanism is employed, and the inserts are used as needed according to the configuration of the chair back mounting member to be used for a particular chair. The mounting area again includes an engagement arrangement for securing the chair back mounting member to the chair control mechanism, which may either be a fixed-position or adjustable engagement arrangement. 
     Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate the best mode presently contemplated of carrying out the invention. 
     In the drawings: 
     FIG. 1 is a partial side elevation view of a chair incorporating a first embodiment of the chair back mounting system of the invention; 
     FIG. 2 is an exploded isometric view showing the components of the chair back mounting system of FIG. 1; 
     FIG. 3 is a partial bottom plan view of the chair back mounting system of FIG. 1, with reference to line  3 — 3  of FIG. 1; 
     FIG. 4 is a partial section view taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a view similar to FIG. 1, showing a second embodiment of the chair back mounting system of the invention; 
     FIG. 6 is a partial bottom plan view of the chair back mounting system of FIG. 5, with reference to line  6 — 6  of FIG. 5; 
     FIG. 7 is a partial section view taken along line  7 — 7  of FIG. 6, showing the mounting area for engaging a chair back support member having a first configuration; 
     FIG. 8 is a view similar to FIG. 7, showing inserts for altering the configuration of the mounting area according to a different configuration of the chair back mounting member; and 
     FIG. 9 is a partial exploded isometric view showing the manner in which inserts are employed to alter the configuration of the mounting area as in FIG.  8 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 illustrates a chair  10  having a seat  12  and a back  14 . A chair control mechanism  16  is mounted to the underside of seat  12 . Chair control mechanism  16  is mounted to the upper end of a support column  18 , which may be in the form of a gas cylinder forming a part of a conventional chair base for supporting seat  12  above a supporting surface such as a floor. The basic components and construction of chair control mechanism  16  are known to those skilled in the art, and chair control mechanism  16  may be that such as is disclosed in Miotto et al U.S. Pat. No. 5,280,998 issued Jan. 25, 1994, the disclosure of which is hereby incorporated by reference. 
     Chair back  14  is mounted to a back support member  20 , which defines an upright back mounting section  22  to which back  14  is secured, and a lower seat mounting section  24 . Back support member  20  is generally known as a J-bar, which is commonly used to mount a chair back such as  14  to the underside of seat  12  or to a chair control mechanism such as  16 . 
     Chair control mechanism  16  generally includes a pair of mounting arms  26  secured to the underside of seat  12 , and a rigid support section  28  secured at its rearward end to the upper end of support column  18 . Mounting arms  26  are pivotably mounted to the forward end of support section  28  by means of a pivot pin  30 . The longitudinal axis of pivot pin  30  defines a pivot axis about which seat  12  is pivotable relative to support section  28 , for providing rearward pivoting movement of seat  12  relative to support column  18 . A spring  32  biases mounting arms  26  away from support section  28 , for urging seat  12  toward an upright position as shown in FIG.  1 . 
     A receiver  32  is mounted to the rearward ends of mounting arms  26  for securing seat mounting section  24  of back support member  20  to chair control mechanism  16 . Receiver  32  includes a pair of spaced apart side mounting sections  34 , each of which is mounted to one of mounting arms  26  by means of a pair of bolts or other threaded fasteners  36 . A rear end section  38  extends between mounting sections  34 . Rear end section  38  defines an end wall  40 , which extends between a pair of sidewalls  42  defined by mounting sections  34 . Rear end section  38  defines an upper wall  44 , and a mounting area  46  is stamped into upper wall  44 . Mounting area  46  is adapted for use in engaging seat mounting section  24  of back support member  20 , in a manner to be explained. Mounting area  46  defines an engagement surface  48  having a series of threaded apertures  50 . 
     An opening  52  is formed in end wall  40  of rear end section  38 . Opening  52  is rectangular in shape, and is in alignment with engagement surface  48  of mounting area  46  in a front-rear direction relative to seat  12 . Opening  52  has a width greater than that of mounting area  46 , and one of a series of inserts  54   a,    54   b,    54   c  is adapted for placement within opening  52 . FIGS. 3 and 4 illustrate insert  54   a  engaged within opening  52 . Inserts  54   a,    54   b  and  54   c  are similar in overall configuration, in that each is adapted for mounting to receiver  32  by engagement within opening  52  as illustrated in FIGS. 3 and 4 with respect to insert  54   a.  Inserts  54   a,    54   b  and  54   c  differ in that each includes a differently configured passage  56   a,    56   b  and  56   c,  respectively, for receiving a respective lower seat mounting section  24   a,    24   b,    24   c  of differently dimensioned back support members  20 . In a manner to be explained, seat mounting sections  24   a,    24   b  and  24   c  differ from each other in width and/or thickness. 
     FIGS. 3 and 4 illustrate insert  54   a  mounted within opening  52 , and it is understood that the following description applies equally to engagement of inserts  54   b,    54   c  within opening  52 . 
     As shown in FIGS. 3 and 4, insert  54   a  includes a rear face section  58  and a mounting section  60  extending forwardly from rear face section  58 . Mounting section  60  defines an external configuration which matches that of opening  52 . As illustrated, mounting section  60  has a rectangular shape, and defines walls in close proximity to the edges of opening  52  when mounting section  60  is received within opening  52 . As shown in FIG. 4, mounting section  60  includes upper and lower walls  62 ,  64 , respectively, and end walls extend between and interconnect upper and lower walls  62 ,  64 . A series of mounting tabs  66 ,  68  are formed on upper and lower walls  62 ,  64 , respectively. Mounting tabs  66 ,  68  are divergent in a forward-rearward direction, and provide a snap-fit engagement of insert  54   a  within opening  52  upon application of a forward push-on force by which insert  54   a  is moved into opening  52 . A space is defined between the rearward ends of mounting tabs  66 ,  68  and the forward surface of rear face section  58 , to securely engage insert  54   a  within recess  52 . When insert  54   a  is mounted within opening  52  in this manner, the downwardly facing surface of upper wall  62 , shown at  70 , is substantially coplanar with engagement surface  48  of mounting area  46 . 
     Passage  56   a  in insert  54   a  is configured such that the height of passage  56   a  closely matches the thickness of seat mounting section  24 , shown at X in FIG. 2, and the width of passage  56   a  closely matches the width of seat mounting section  24   a,  shown at Y. After engagement of insert  54   a  within opening  52 , seat mounting section  24   a  is inserted into and through passage  56   a  such that openings in seat mounting section  24   a,  shown at  72   a,  are in alignment with openings  50  in mounting area  46  and a central slot  74   a  in seat mounting section  24   a  is in alignment with the central one of openings  50  in mounting area  46 . Threaded fasteners  76  (FIG. 4) are then engaged with openings  50  through openings  72   a,  as shown in FIG. 4, to fixedly secure back support member  20  to receiver  32 . Alternatively, a hand screw  78  may be employed in place of fasteners  76  for engagement with the central one of openings  50  through slot  74   a,  to provide an adjustable mounting of back support member  20  to receiver  32 . In either a fixed mounting or an adjustable mounting, insert  54   a  functions to fix seat mounting section  24   a  in position relative to receiver  32  due to the close tolerances between the edges of passage  56   a  and the facing surfaces of seat mounting section  24   a.    
     Seat mounting section  24   b  has a height X′ which is greater than height X of seat mounting section  24   a,  and has a width Y similar to that of seat mounting section  24   a.  Seat mounting section  24   c  has a height X′ and a width Y′ is less than width Y of seat mounting sections  24   a,    24   b.  Passage  56   b  of insert  54   b  has a configuration which closely matches that of seat mounting section  24   b,  and passage  56   c  of insert  54   c  has a configuration which closely matches that of seat mounting section  24   c.  When a back support member  20  having seat mounting section  24   b  or  24   c  is employed, the appropriate insert  54   b  or  54   c  is engaged within opening  52  in the same manner as described above with respect to insert  54   a.  Inserts  54   b  and  54   c  function to fix the position of seat mounting sections  24   b,    24   c,  respectively, relative to receiver  32 , and to guide inward and outward movement of seat mounting sections  24   b,    24   c  relative to receiver  32 . 
     This arrangement enables a manufacturer to provide a single structure for receiver  32  which can be used with a back support member  20  having a lower seat mounting section  24  of varying configurations such as  24   a,    24   b,    24   c,  simply by engaging the appropriate insert, such as  54   a - 54   c,  within the opening  52  formed in rear end wall  40  of receiver  32 . The manufacturer need only ensure that opening  52  is dimensioned so as to accommodate the maximum width and thickness of each seat mounting section  24  which will be used, and the inserts such as  54   a - 54   c  is molded to accommodate such mounting within opening  52  and to define a passage having the appropriate configuration for each seat mounting section. In addition, this system enables a user to change out inserts  54   a - 54   c  as needed if it is desired to replace an existing back support member  20  with another having a different seat mounting section configuration. 
     FIGS. 5-9 illustrate a chair control mechanism  80  of a different type than chair control mechanism  16  shown in FIGS. 1-4. Chair control mechanism  80  is positioned similarly to chair control mechanism  16  with respect to the general components of chair  10 , in that chair control mechanism  80  is mounted to the underside of seat  12  and is secured to the upper end of support column  18 . The general construction and operation of chair control mechanism  80  is disclosed in copending application Ser. No. 09/197,039 filed Nov. 20, 1998, the disclosure of which is hereby incorporated by reference. Generally, chair control mechanism  80  includes a seat mounting section  82  mounted to the underside of seat  12 , a support section  84  mounted to the upper end of support column  18 , and an intermediate member  86  interconnected with both seat mounting section  82  and support section  84 . Lower seat mounting section  24  of back support member  20  is secured to intermediate member  86  for mounting back  14  relative to seat  12 . Chair control mechanism  80  is a synchronous-type mechanism, in that the angle of back  14  relative to seat  12  changes as seat  12  is pivoted forwardly and rearwardly relative to support column  18 . 
     The above-referenced application discloses lower seat mounting section  24  of back support member  20  as being fixed to intermediate member  86 . In accordance with the present invention, the rearward end of intermediate member  86  is provided with a mounting arrangement for enabling seat mounting sections  24  of varying dimensions to be secured to intermediate member  86 . 
     Referring to FIGS. 6-9, intermediate member  86  includes a pair of sidewalls  88  and an upper wall  90  extending between and interconnecting the upper ends of sidewalls  88 . Inwardly extending pierced protrusions  92  are formed in sidewalls  88  at a location spaced below the lower surface of upper wall  90 . Each protrusion formed in sidewalls  88  is an inwardly pierced member formed from the material of sidewall  88 . Protrusions  92  are located such that a front protrusion  92  and a rear protrusion  92  is formed on each sidewall  88 . The front and rear protrusions  92  on each sidewall  88  are located opposite the front and rear protrusions on the other sidewall  88 . 
     Each protrusion  92  is arcuate in shape, and is spaced from the lower surface of upper wall  90  a predetermined distance which corresponds to the maximum thickness of the seat mounting section  24  of each back support member  20  in connection with which chair control mechanism  80  is to be used. In addition, sidewalls  88  of intermediate member  86  are spaced apart a distance such that the facing surfaces of sidewalls  88  are adapted to receive therebetween the maximum width of lower seat mounting section  24  for each back support member  20  in connection with chair control mechanism  80  is to be used. In this manner, sidewalls  88  in combination with the lower surface of upper wall  90  and the surfaces of protrusions  92  which face upper wall  90 , cooperate to define a mounting area for receiving the inner end of a seat mounting section  24   a  having a maximum width and maximum height. As shown in FIGS. 6 and 7, seat mounting section  24   a  having a maximum thickness X and a width corresponding to the spacing between sidewalls  88  is received within the area defined by sidewalls  88 , upper wall  90  and protrusions  92 . Threaded bosses  94  are formed in upper wall  90 , and are adapted to receive the threads of a set of fasteners  96  which extend through openings in seat mounting section  24   a  in alignment with bosses  94 , for fixedly mounting the inner end of seat mounting section  24   a  to intermediate member  86 . Alternatively, a hand screw  98  may be employed in place of fasteners  96  for engagement with a central one of bosses  94  through a slot  100  formed in seat mounting section  24   a,  for mounting back support member  20  to intermediate member  86  so as to provide adjustability in the forward and rearward position of back  14  relative to seat  12 . 
     Referring to FIGS. 8 and 9, a differently dimensioned seat mounting section  24   a  can be engaged with intermediate member  86  by use of a set of insert members  102 , each of which is adapted for engagement with one of protrusions  92 . Each insert member  102  includes a stem  104  which is configured so as to be received within a space  108  defined between the inner surface of each sidewall  88  and the arcuate inner surface of each protrusion  92 , and a head  106  located at the upper end of stem  104 . Head  106  is dimensioned such that, when stem  104  is received within space  108 , head  104  rests on the upper surface of each protrusion  92 . In this manner, the mounting height for receiving seat mounting section  24   b,  located between each protrusion  92  and the facing lower surface of upper wall  90 , is reduced by the thickness of head  106 . Thus, a seat mounting section  24   b  (FIG.  8 ), having a thickness X′ less than the thickness X of seat mounting section  24   a  (FIG.  7 ), is receivable within the mounting area defined by sidewalls  88 , upper wall  90  and protrusions  92 . 
     It can thus be appreciated that insert members  102  in the embodiment of FIGS. 5-9 function similarly to inserts  54   a - 54   c  to alter the configuration of the area within which the seat mounting section  24  of a back support  20  is received, to accommodate seat mounting sections  24  of varying dimensions. While the drawings illustrate one version of an insert member  102  which can be used to alter the configuration of the receiving area, it should be understood that other configurations can be employed to further alter the height of the receiving area and/or the width of the receiving area. For example, an extension like stem  104  may be formed above head  106  to reduce the width of the receiving area. In such a case, an opening is formed in upper wall  90  so as to enable the stem  104  of such an insert to be inserted in an upward-downward direction into space  108 . 
     Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.