Patent Publication Number: US-2012038197-A1

Title: Leg support insert for seating apparatus

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to seating applications, and more particularly to a structure and method for attaching a leg support structure to a seat body in an institutional seating application. 
     Institutional chairs are well known for use in a variety of applications in which it is desired to have multiple, and often very many, chairs that are durable and easy to arrange in a variety of configurations. For instance, institutional chairs are commonly arranged in rows and used in classroom and office applications. 
     A typical institutional chair includes a seat body portion that includes a generally horizontal seat portion and a generally vertical seat back portion extending upwardly from the seat portion. The seat body portion may be formed from a variety of materials, such as molded plastic, fiberglass or metal, and is often with a curved shape to provide a degree of comfort to a user sitting in the chair. The seat body portion is supported above the ground at a desired height by a leg support structure, which is generally formed from metal and includes legs that are connected together at their upper ends by one or more cross pieces. 
     Problems often arise in the attachment of the leg support structure to the seat body. Many institutional chairs include self tapping screw holes formed in the lower surface of the plastic seat portion, such that fasteners can extend through the leg support structure directly into the plastic seat body. Attachment by this method is relatively easy, but in many cases the threaded screw bosses—which require thicker areas of plastic material on the seat body—show through on the upper surface of the seat body, creating unsightly sink marks on the visible portions of the seat surface. One attempt to overcome this problem is to attach one or more separate plastic pieces to the lower surface of the seat body. The plastic pieces can be attached without creating sink marks on the upper surface of the seat. In one known construction, a steel plate is attached to the plastic pieces and the leg support structure is attached to the steel plate, either by fasteners or by welding the leg support structure to the steel plate. This construction generally overcomes the problem of sink marks, but the additional steel plate adds unwanted cost, manufacturing time and weight to the chair. 
     SUMMARY OF THE INVENTION 
     The present invention provides a chair construction including seat inserts that attach to the lower surface of a seat body and are capable of receiving the leg support structure without a separate metal plate. 
     In one embodiment, the chair includes four plastic seat inserts molded to the lower surface of a plastic seat body. The inserts each include a notch that is sized to receive a portion of the leg support structure, such as a cross member. The cross member can fit into the notch and attach to the insert without attaching directly to the seat body. 
     In a more particular embodiment, the seat inserts each include a cone shaped sidewall with an upper portion that is molded into a similarly shaped receptacle on the lower surface of the seat body. The inserts may each include a fastener hole that extends through a lower wall of the insert and into an upper wall of the notch without extending completely through the upper wall of the insert. The inserts may be spaced apart on the lower surface of the seat body such that a first leg support cross member can be inserted into the notches of two of the inserts and a second leg support cross member can be inserted into the notches of the other two inserts. The cross members may include holes aligned with the holes in the inserts to enable insertion of fasteners through the inserts and the cross member. In one embodiment, the notches may include a curved cross section that is shaped to correspond to the tubular shape of the leg support cross members. The notches may additionally include a mouth that is slightly narrower than the central portion of the notch to prevent the leg support cross member from pulling out of the notch after it has been inserted. 
     The attachment of inserts to the lower surface of the seat body enables the use of thinner materials within the seat body, reducing the potential for sink marks in the upper surface of the seat body. At the same time, the notches in the inserts can eliminate the need for a plate or similar structure for attaching a leg support structure to the seat body. These and other objects, advantages, and features of the invention will be more fully understood and appreciated by reference to the description of the current embodiment and the drawings. 
     Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited to the details of operation or to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention may be implemented in various other embodiments and of being practiced or being carried out in alternative ways not expressly disclosed herein. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. Further, enumeration may be used in the description of various embodiments. Unless otherwise expressly stated, the use of enumeration should not be construed as limiting the invention to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the invention any additional steps or components that might be combined with or into the enumerated steps or components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a bottom perspective view of a chair including seat inserts according to one embodiment of the present invention. 
         FIG. 2  is an exploded view of a chair including seat inserts according to one embodiment. 
         FIG. 3  is a cross sectional view of a portion of a seat surface, a seat insert and a portion of a chair leg. 
         FIG. 4  is a bottom perspective view of a chair including seat inserts according to a second embodiment of the present invention. 
         FIG. 5  is an exploded view of a chair including seat inserts according to the second embodiment. 
         FIG. 6  is a bottom perspective view of a chair including seat inserts according to a third embodiment of the present invention. 
         FIG. 7  is a cross sectional view taken along the line  7 - 7  in  FIG. 6 . 
         FIG. 8  is a cross sectional view taken along the line  8 - 8  in  FIG. 6 . 
     
    
    
     DESCRIPTION OF THE CURRENT EMBODIMENT 
     I. Overview 
     A chair according to one embodiment of the present invention is shown in  FIGS. 1-3  and generally designated  10 . The chair  10  generally includes a seat body  12 , a leg structure  14  and one or more seat inserts  16 . The seat body  12  includes a seat portion  18  and a seat back portion  20  and forms the portion of the seat that contacts the user. The leg structure  14  includes legs  22  that extend downwardly from the seat body  12  to engage the floor and to support the seat body  12  at a desired distance above the floor. The seat inserts  16  attach the seat body  12  to the leg structure  16 . 
     II. Structure 
     The seat body  12  may be formed form a variety of materials, and in one embodiment the seat body  12  is formed from a single piece of molded plastic, such as injection molded polypropylene. In another embodiment, the seat body  12  may be formed form multiple pieces of the same or different materials that are fastened together by conventional methods. As shown in  FIGS. 1 and 2 , the seat body  12  may include a seat portion  18  and a seat back portion  20 . The seat portion  18  may include an upper surface  24  for engaging the user and a lower surface  26  opposite the upper surface  24 . The upper surface  24  is generally horizontal, but may be contoured to provide a comfortable seating surface for a user. As shown in  FIGS. 1 and 3 , the lower surface  26  extends generally horizontally but is contoured to match the shape of the upper surface, and may be configured to attach to the seat inserts  16 . In one embodiment, the seat portion  18  includes a front edge  36 , first and second side edges  38 ,  40 , and a rear edge  42 . The seat back portion  20  may extend upwardly from the rear edge  42 , and may be contoured to comfortably support the back of a user. 
     In the illustrated embodiment, the lower surface includes four receptacles  28   a - d  for attaching to the seat inserts  16 . The receptacles  28   a - d  may be formed integrally with the seat body  12 . For example, they receptacles  28   a - d  may be injection molded with the seat body  12  or the seat portion  18  as a single piece. As illustrated, each receptacle  28   a - d  includes a generally circular sidewall  30  that extends outwardly from the lower surface  26  of the seat portion  18  from a base  32  to a distal edge  34 . The sidewall  30  may angle inwardly from the base  32  to the distal edge  34 , such that each receptacle has a generally frustoconical shape. In an alternative embodiment, the receptacles may have a different shape, or they may be formed from a different material than the seat portion  18  and attached to the seat portion  18 . The receptacles  28   a - d  may be spaced apart on the lower surface  26  of the seat portion  18 , such that a first receptacle  28   a  is located proximate to the corner between the front edge  36  and the first side edge  38 , the second receptacle  28   b  is located proximate to the corner between the front edge  36  and the second side edge  40 , the third receptacle  28   c  is located proximate to the corner between the rear edge  42  and the first side edge  38  and the fourth receptacle  28   d  is located proximate to the corner between the rear edge  42  and the second side edge  40 . Alternatively, the positioning of the receptacles or other attachment structure may vary from application to application. 
     The leg structure  14  supports the seat body  12  at a desired height above the ground. In one embodiment, the leg structure  14  is formed from steel or another metal; however, the leg structure  14  may be formed from a variety of materials with sufficient strength to support the seat body  12  and the weight of a user sitting on the seat body  12 . A variety of leg configurations are known and may be utilized for supporting the seat body  12 , depending on the desired application. One leg structure configuration is shown in  FIGS. 1-3 . In this embodiment, the leg structure  14  includes a first support member  50  and a second support member  52 . The support member  50  includes a horizontal cross piece  54 . A first leg  60  extends downwardly from the first end and a second leg  62  extends downwardly from the second end. The cross piece  54  may define a pair of holes  66 ,  68  that extend through the cross piece  54  and are spaced apart at approximately the same distance as the receptacles  28   c  and  28   d . The support member  52  includes a horizontal cross piece  74 . A first leg  80  extends downwardly from the first end and a second leg  82  extends downwardly from the second end. The cross piece  74  may define a pair of holes  86 ,  88  that extend through the cross piece  74  and are spaced apart at approximately the same distance as the first  28   a  and second  28   b  receptacles. As shown in  FIG. 3 , the support members  50 ,  52  may be tubular, and may have an oval shaped cross-section, although other cross-sectional shapes may be used. 
     A second leg structure configuration  114  is shown in  FIGS. 4 and 5 . In this embodiment, the leg structure  114  is a cantilever design, including a pair of generally horizontal ground supports  116 ,  118 , a pair of legs  120 ,  122  extending upwardly from the ground supports  116 ,  118 , and a generally U-shaped support member  124  extending from the legs  120 ,  122 . The U-shaped support member  124  may include side members  130 ,  132  that are spaced apart at approximately the same distance as the first  28   a  and second  28   b  receptacles and a front member  134  extending between the side members  130 ,  132  opposite the legs  120 ,  122 . The first side member  130  may define a pair of holes  136 ,  138  that extend through the side member  130  and are spaced apart approximately the distance between the receptacles  28   b  and  28   d . The second side member  132  may define a pair of holes  140 ,  142  that extend through the side member  132  and are spaced apart approximately the distance between the receptacles  28   a  and  28   c.    
     The seat inserts  16  attach between the seat body  12  and the leg structure  14 . The inserts may be formed from a variety of materials, such as plastic or metal. In one embodiment, the inserts are formed from injection molded nylon; however, other plastics may be used. In another embodiment, the inserts  16  are cast metal pieces. In one embodiment, the chair  10  includes four seat inserts  16 , with each seat insert  16  including a circular bottom wall  150 , a generally circular top wall  152 , and a sidewall  154  extending between the top wall  150  and bottom wall  152 . As illustrated, the inserts  16  are generally frustoconical in shape with the sidewall  154  angling inwardly as it extends from the top wall  152  towards the bottom wall  150 . The angle of the sidewall  154  may match the angle of the sidewall  30  of the receptacles  28   a - d  to enable the sidewall  154  of each insert to engage the sidewall  30  of its respective receptacle  28   a - d  to retain the insert  16  within the sidewall  30  of the receptacle  28   a - d . In one embodiment, each insert includes a notch  160  extending into the sidewall  154  between the bottom wall  150  and the top wall  152  for receiving a portion of the leg structure  14 . In the illustrated embodiment, the notch  160  extends into the sidewall  154  a distance approximately equal to ¾ of the diameter of the insert  16 . The notch  16  includes an upper wall  162 , a lower wall  164  and a rear wall  166  that may be curved to match the cross sectional shape of the leg structure  14  when the leg structure  14  is seated against the rear wall  166 . The notch  160  further includes a mouth  168  that may be slightly narrower than the cross section of the leg structure  14  to encourage the leg structure  14  to seat against the rear wall  166  and to prevent the leg structure  14  from pulling out of the notch  160  after it has been inserted. The bottom wall  150  may include a hole  170 , which may extend into the upper wall  162  of the notch  160 , but in one embodiment does not extend entirely through upper wall  162  of the insert  16 . As illustrated, the hole  170  is positioned in the center of the bottom wall  150 . In one embodiment, the top wall  152  is contoured to match the contour of the lower surface  26  of the seat portion to enable the insert  16  to fit flush against the lower surface  26  of the seat portion  18 . The four inserts for each seat may each have a uniform top wall  152 , such that the same insert  16  can be attached to the seat portion  18  in four different locations; however, in one embodiment, each insert  16  may have a different shape to accommodate differences in the contour of the lower surface  26  of the seat portion  18 . 
     As shown in  FIGS. 1-3 , in one embodiment, the seat inserts  16  are attached to the receptacles  28   a - d  in a manner that will enable the inserts  16  to receive the leg structure  14  shown in  FIGS. 1-3 . In this embodiment, the inserts  16  in the receptacles  28   a  and  28   b  are positioned with their notches  160  facing in the same direction, towards the receptacles  28   c  and  28   d  respectively. The inserts  16  in the receptacles  28   c  and  28   d  face towards the receptacles  28   a  and  28   b  respectively. The inserts  16  in the receptacles  28   a  and  28   b  are spaced apart to receive the cross piece  74  of the second support member  52  with the holes  86 ,  88  in the cross piece  74  aligned with the holes  170  in the respective inserts  16 . The seat inserts  16  in the receptacles  28   c  and  28   d  are spaced apart to receive the cross piece  54  of the first support member  50  with the holes  66 ,  68  in the cross piece  54  aligned with the holes  170  in the respective inserts  16 . In another embodiment, the inserts  16  may be attached to the receptacles  28   a - d  with the notches  160  facing in other directions not shown in the drawings, with pairs of inserts  16  having their notches aligned along a common axis such that the cross pieces  54 ,  74  can each be inserted into the notches  160  of two of the seat inserts  16 . The inserts  16  may be attached to the receptacles  28   a - d , or to another portion of the seat body  12  by any conventional method. 
     In one embodiment, the sidewall  30  of each receptacle  28   a - d  extends around an upper portion of the sidewall  154  of an insert  16  to retain the insert  16  in the receptacle  28   a - d . The sidewall  30  may be molded about the sidewall  154  of the insert  16 , for example, by placing the insert  16  into a mold and forming the seat body  12  in the mold with one of the receptacles  28   a - d  being molded about the insert  16 . Alternatively, the seat inserts  16  may be attached to the seat body  12  by adhesive, sonic welding, one or more fasteners, or another conventional attachment method. When the cross pieces  54  and  74  are positioned within the notches  160 , fasteners  200  may be inserted through the holes  66 ,  68 ,  86  and  88  respectively and into the cross pieces  54 ,  74  to attach the cross pieces  54 ,  74  to the inserts  16 . 
     The configuration of the inserts  16  may be varied depending on the type of leg structure to be connected to the seat body  12 . For instance, as shown in  FIGS. 4-5 , when attaching the leg structure  114  to the seat body  12 , the inserts  16  may all be positioned to face in the same direction to enable insertion of the each of the side members  130 ,  132  into the notches  160  of two of the inserts  16 . The inserts  16  are spaced apart such that the holes  170  in the inserts each align with one of the holes  136 ,  138 ,  140 ,  142  in one of the side members  130 ,  132 . 
     Another embodiment is shown in  FIGS. 6-8 . Some attributes of this embodiment may be configured similar to the other embodiments and will not be described here. In the illustrated embodiment, the receptacles  28   a ′- d ′ define two notches  160 ′ substantially perpendicular to one another in their bottom surfaces for receiving the leg structure  14 . This configuration allows the receptacles  28   a ′- d ′ to receive the leg structure  14  in either notch  160 ′, which allows the leg structure  14  to be received in multiple orientations. For example, the leg structure  14  may be received in the orientation shown in  FIG. 6 , or may be received in three other orientations, each orientation obtained by rotating the leg structure  14  by 90°. Optionally, the receptacles  28   a ′- d ′ may define more than two notches  160 ′, which would increase the number of possible orientations of leg structure  14 . 
     In this embodiment, the seat inserts  16 ′ are formed separately from the seat portion  18 ′ and are secured over the leg structure  14  to secure the leg structure  14  to the seat portion  18 ′. As with the other embodiments and as shown in  FIGS. 7-8 , the angle of the sidewall  154 ′ may match the angle of the sidewall  30 ′ of the receptacles  28   a ′- d ′. The seat inserts  16 ′ may be secured using any method described in connection with the other embodiments. 
     As shown in  FIGS. 7 and 8 , the receptacle  28 ′ includes a bottom surface  302  and the seat insert  16 ′ includes a top surface  300 . In the illustrated embodiment, the two surfaces  300 ,  302  are spaced from one another. In other embodiments, the two surfaces  300 ,  302  may engage or interface with one another. The seat inserts  16 ′ may be made of any material described in connection with the other embodiments and may be made using any manufacturing process described in connection with the other embodiments. 
     III. Manufacture 
     In one embodiment, the present invention is manufactured by the steps of: (a) forming the seat inserts  16 , (b) forming the seat body  12 , (c) forming the leg structure  14 , (d) attaching the seat inserts  16  to the seat body and (e) attaching the leg structure  14  to the seat inserts  16 . 
     The seat inserts  16  may be formed from a variety of conventional methods. In one embodiment, the seat inserts  16  are formed by injection molding. Similarly, the seat body  12  may be formed by any conventional method, and in one embodiment the seat body  12  is formed by injection molding the seat body  12  as a single piece of material, including the receptacles  28   a - d  on the lower surface  26  of the seat portion  18 . In one embodiment, the seat inserts  16  are formed in a first mold, and then removed from the first mold and inserted into a second mold. The second mold may be shaped to form the seat body  12 . The plastic is injected into the second mold such that it forms the receptacles  28   a - d  extending around the seat inserts  16 , with one insert  16  positioned in each receptacle  28   a - d  and with the inserts  16  each facing in the desired direction with respect to the seat body  12 . In another embodiment, the inserts  16  may be formed after the seat body  12 , and attached to the seat body  12  by another method. For example, in the embodiment shown in  FIGS. 6-8 , the inserts  16 ′ may be separately attached to the seat portion  18  after the inserts  16 ′ are formed. 
     The leg structure  14  is attached to the seat inserts  16  by inserting each of the cross pieces  54 ,  74  into two of the notches  160  in the inserts  16 . In one embodiment, the cross piece  54  is inserted into the notches  160  of the inserts  16  in the receptacles  28   a - b  and the cross piece  74  is inserted into the notches  160  of the inserts  16  in the receptacles  28   c - d . The curved cross sectional shape of the notches  160 , with a mouth  168  that is slightly narrower than the remaining portion of the notch  160  enables the cross pieces  54 ,  74  to snap fit into the notches  160  and prevents unwanted removal from the notches  160 . After the cross pieces  54 ,  74  are inserted into the notches  160  of the seat inserts  16 , fasteners  200  can be inserted into the holes  170  in each of the seat inserts  16  and through the holes  66 ,  68 ,  86 ,  88  in the cross pieces  54 ,  74  and into the holes in the upper wall  162  of each notch  160  to secure the cross pieces  54 ,  74  within the seat inserts  16 . Similarly, the leg structure  114  may be secured to the inserts  16  by inserting the side members  130 ,  132  into notches  160  in the seat inserts  16  and inserting fasteners  200  through the holes  170  and into the holes  136 ,  138 ,  140 ,  142  in the side members. In the embodiment shown in  FIGS. 6-8 , the leg structure  14  may be inserted into one or more selected notches  160 ′ in a selected orientation. The seat inserts  16 ′ may be placed over the leg structure  14 , aligned with a respective receptacle  28   a ′- d ′, and secured by inserting one or more fasteners  200 ′ into holes  170 ′. 
     Directional terms, such as “vertical,” “horizontal,” “top,” “bottom,” “upper,” “lower,” “inner,” “inwardly,” “outer” and “outwardly,” are used to assist in describing the invention based on the orientation of the embodiments shown in the illustrations. The use of directional terms should not be interpreted to limit the invention to packages of any specific orientation(s). 
     The above description is that of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments of the invention or to limit the scope of the claims to the specific elements illustrated or described in connection with these embodiments. For example, and without limitation, any individual element(s) of the described invention may be replaced by alternative elements that provide substantially similar functionality or otherwise provide adequate operation. This includes, for example, presently known alternative elements, such as those that might be currently known to one skilled in the art, and alternative elements that may be developed in the future, such as those that one skilled in the art might, upon development, recognize as an alternative. Further, the disclosed embodiments include a plurality of features that are described in concert and that might cooperatively provide a collection of benefits. The present invention is not limited to only those embodiments that include all of these features or that provide all of the stated benefits, except to the extent otherwise expressly set forth in the issued claims. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.