Abstract:
A seat assembly having a tunable tie bar is provided and includes a main pivot and a housing operably supporting the tie bar. The housing is fixedly attached to a seatback of the seat assembly and includes C-shaped members fixedly joined together to provide a space in which the tie bar is disposed. The tie bar is fixedly attached to the housing and is in engagement with the main pivot, whereby the tie bar reacts against the main pivot to provide the seatback with sufficient support. The tie bar serves to strengthen the housing and ultimately provide the seatback with sufficient strength to support an occupant and the accompanying seatbelt loads associated with a seat-mounted retractor assembly. The tie bar is tunable between different seating applications and as such, allows the housing to be used in various seating applications and does not require extensive design and tooling for each application.

Description:
FIELD OF THE INVENTION 
     The present invention relates to seat assemblies and, more particularly, to a support structure for a seat assembly. 
     BACKGROUND OF THE INVENTION 
     Seat assemblies, such as those used in vehicles, generally include a support structure interconnected between a seatback and a seat bottom for strengthening the seat assembly and providing support to an occupant. Many seat assemblies further include a mounting location integrally formed of the support structure for fixedly attaching a seatbelt retractor assembly thereto. Attaching a retractor assembly directly to the support structure of a seat assembly enhances occupant comfort and improves passenger compartment aesthetics. For example, mounting the seatbelt retractor to a seat assembly improves occupant comfort as the relationship of the seatbelt to the occupant remains constant throughout a range of angular adjustments of the seatback relative to the seat bottom. In addition to appearance and occupant comfort, mounting the retractor assembly directly to the seat assembly reduces assembly time and provides manufacturing flexibility. For example, vehicles such as convertibles, which generally do not have an upwardly extending B-pillar, do not include a convenient location on which to mount the retractor assembly, but can be manufactured with a seat assembly having an integrated retractor assembly. 
     In such an arrangement, the structure of the seat assembly must be of sufficient strength to accommodate the potentially high loads that may be generated as a result of vehicle deceleration from impact, severe braking, or the like. In these situations, the seatback plays a role as many seatbelt assemblies are shoulder mounted requiring mounting on an upper portion of the seatback. Alternatively, some seatbelt assemblies mount the retractor assembly to the seat bottom or other vehicle structure while still routing seatbelt webbing through the seatback to provide a shoulder-type restraint integral with the seatback. In either situation, loading of a shoulder-mounted seatbelt assembly causes a force to be applied at the interface of the seatbelt and the seatback under deceleration of the vehicle. 
     The force applied to the seatback is typically transmitted through the seatback structure to the seat bottom and ultimately to the structure of the vehicle through a pivotal connection of the seatback and the seat bottom. For shoulder-mounted seatbelt assemblies the force is magnified due to the moment arm extending from the seatback pivot to the point at which the seatbelt loads the seatback. As such, the seatback structure must be strong enough to transmit the generally high loads resulting from vehicle deceleration while also accommodating articulation of the seatback relative to the seat bottom. 
     Known seat assemblies providing for attachment of a seat belt retractor assembly to a vehicle seat suffer from the disadvantage of not efficiently and effectively transferring deceleration loads received by the seatback to the vehicle structure. More specifically, known designs for structured seat assemblies have been unable to fully retain the operation features demanded by consumers without requiring complex arrangements for pivotally mounting the seatback to the seat bottom. Further, known seat assemblies require a seat structure specific to each application, including design time and tooling for each independent application. While functionally acceptable, these complex arrangements are often weight prohibitive, cost prohibitive, or both. 
     Therefore, a seat assembly having a structure capable of pivotably supporting a seatback relative a seat bottom while providing enough strength to support a seatbelt assembly and the loads associated therewith is desirable in the industry. Furthermore, providing a seatback structure capable of adjustment and modification for use in various seating applications and varying vehicle seat designs while minimizing design time and tooling investment is also desirable. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a seat assembly with a tunable tie bar including a housing operably supporting the tie bar and a main pivot for interaction with the tie bar under a loading condition. The housing is fixedly attached to a seatback of the seat assembly and includes first and second C-shaped members fixedly joined together to form the housing and provide a space therebetween in which the tie bar is disposed. The housing further includes an extension for receiving the main pivot, whereby the main pivot receives a seat structure from a seat bottom and provides for relative rotation between the seatback and the seat bottom. The tie bar is an elongate support arm having a U-shaped extension and attachment apertures disposed along its length. The tie bar is fixedly attached to the housing and is in engagement with the main pivot, whereby the U-shaped extension reacts against the main pivot to provide the seatback with sufficient strength. 
     The tie bar is tunable for different seating applications by adjusting the material properties of the bar, varying the stiffness of the bar by varying the number of apertures formed thereon, or by modifying the interaction of the U-shaped extension and the main pivot. As such, the tunable tie bar allows the use of a common housing in various seating applications and does not require design and tooling of a new housing for each application. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a seatback support structure in accordance with the principals of the present invention; 
     FIG. 2 is an exploded view of the seatback support structure of FIG. 1; 
     FIG. 3 is a side elevational view of the seatback support structure with part of a housing removed to show the internal workings of the seatback support structure; and 
     FIG. 4 is a side view of the seatback support structure in a seat assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     With reference to the drawings, a seat support structure  10  is provided and includes a housing  12 , a tie bar  14 , and a main pivot  16 . The tie bar  14  is in abutting engagement with the main pivot  16  and serves to strengthen the housing  12 . The housing includes first and second housing plates  18 , 20 , between which the tie bar  14  and main pivot  16  are supported. 
     The tie bar  14  is an elongate member operably supported by the housing  12  and includes attachment apertures  24  and an extension  26 . The extension  26  includes a recess  28  having an arcuate surface and extends from the tie bar  14  at the second end as best shown in FIG.  2 . The recess  28  includes a reaction surface  30  for mating engagement with the main pivot  16 , as will be discussed further below. The tie bar  14  further includes attachment apertures  32  for attachment to the housing  12  and optional adjustment apertures  31  for adjusting the overall strength of the tie bar  14 . 
     The housing  12  is an elongate member and includes the first and second housing plates  18 , 20 , and an extension  22 . The first housing plate  18  is a generally C-shaped member having a first portion of the extension  22  integrally formed therewith. The first housing plate  18  includes a series of attachment apertures  34  and first and second pivot apertures  36 , 37 . The attachment apertures  34  include a recess  35  for receiving the head of a fastener (not shown) such that as the fastener is received by the attachment aperture  34  the head does not extend beyond an outer surface of the first housing plate  18 . In one embodiment, the attachment apertures  34  receive a fastener to fixedly attach the housing  12  directly to a seatback. Alternatively, the attachment apertures  34  receive a fastener to fixedly attach the housing  12  to the frame of a seatback. In either situation, providing the housing  12  with a generally smooth outer surface prevents the housing  12  from snagging on the internal workings of a seatback and causing damage. In addition, the attachment apertures  34  include a flange  33  extending on an inner surface of the first housing plate  18  to strengthen the attachment apertures  34  and prevent deformation thereof. 
     The first pivot aperture  36  is disposed generally at the base of the extension  22  and includes a recess  44  and a flange  46  for interaction with a pivot  48 . The pivot  48  includes a head  50  and a cylindrical body  52  as best shown in FIG.  2 . The pivot  48  is received by second housing plate  20  having the head  50  disposed thereon while the first pivot aperture  36  of the first housing plate  18  receives the cylindrical body  52  including a tapered leading edge  54  to facilitate insertion into the first pivot aperture  36 . While the second housing plate  20  is disclosed as receiving the cylindrical body  52  and the head  50 , it should be understood that the first pivot aperture  36  could alternatively receive the head  50  and should be considered within the scope of the present invention. In either situation, the head  50  is received by the recess  44  to provide an outer surface of the housing  12  with a generally smooth outer surface. 
     The first housing plate  18  further includes first and second recesses  38 , 39  having attachment apertures  40  formed therein and a flange  56  generally surrounding the perimeter of the first housing plate  18 . The flange  56  extends from the first housing plate  18  and includes attachment posts  58  and a tab  60 . The flange  56  extends generally around the perimeter of the first housing plate  18  with the exception of an area surrounding the first pivot aperture  36  and an area on either side of the tab  60 , as best shown in FIG.  1 . The flange  56  is removed from the area surrounding the first pivot aperture  36  so as to provide clearance for rotation of the housing  12 , as will be discussed further below. 
     With particular reference to FIG. 2, the second housing plate  20  is shown having a second portion of the extension  22 , a series of attachment apertures  34 , first and second pivot apertures  36 , 37 , and a flange  56   a . In view of the substantial similarity in structure of the first housing plate  18  with the second housing plate  20 , like reference numerals are used hereinafter and in the drawings to identify like components while like reference numerals containing letter extensions are used to identify those components that have been modified. Because the first housing plate  18  is substantially similar to the second housing plate  20 , the description of like components is forgone, whereby modified and new components are described herein below. 
     The flange  56   a  extends from the second housing plate  20  for mating engagement with the flange  56  of the first housing plate  18 . The flange  56   a  is removed at one end of the housing  12  in an area surrounding the first pivot aperture  36  and at a second end as best shown in FIG.  1 . The second housing plate  20  further includes a series of slots  72  for receiving the attachment posts  58  of the first housing plate  20 . The attachment posts  58  guide the first housing plate  18  into mating engagement with the second housing plate  20  and further help to fixedly hold the first and second housing plates  18 , 20  in a fixed relationship to prevent relative rotation therebetween. A recess  74  is formed by the interaction of flange  56  and flange  56   a  and extends longitudinally through the housing  12  as best shown in FIG.  1 . The recess  74  is open at a first end around the first pivot  36  and at a second end near tab  60 . The tie bar  14  is disposed within recess  74  and is held in a fixed relationship thereto by a pair of rivets  76 . 
     The rives  76  include first, second, third, fourth, and fifth cylindrical sections  78 , 80 , 82 , 84 , 86 . The first cylindrical section  78  is received by attachment aperture  40  of the first housing plate  18 . The second cylindrical section  80  is disposed adjacent the first cylindrical section  78  and includes a larger diameter than that of the first cylindrical section  78 , thereby forming a first ridge  79 . The first ridge  79  abuts an inner surface of the first housing plate  18  and as such determines the depth that the first cylindrical section  78  is inserted into the attachment aperture  40 . The third cylindrical section  82  is disposed between the second and fourth cylindrical sections  80 , 84  and includes a larger diameter than that of both the second and fourth cylindrical sections  80 , 84 . The fourth cylindrical section  84  is disposed between the third and fifth cylindrical sections  82 , 86  and includes a larger diameter than that of the fifth cylindrical section  86 , thereby forming a second ridge  87 . The fifth cylindrical section  86  is received by the attachment aperture  40  of the second housing plate  20  such that the second ridge  87  abuts an inner surface of the second housing plate  20 , thereby determining the depth that the fifth cylindrical section  86  is inserted into the attachment aperture  40 . 
     The first and second ridges  78 , 87  serve as a spacer between the first and second housing plates  18 , 20 , thereby defining the width of the recess  74 . The second cylindrical section  80  is received by the attachment aperture  32  of the tie bar  14  to fixedly attach the tie bar  14  to the housing  12 . The third cylindrical section  82  cooperates with an inner surface of the first housing plate  18  to fixedly hold the tie bar  14  therebetween and prevent movement of the tie bar  14  along the second cylindrical section  80 . As previously mentioned, the first and fifth cylindrical sections  78 , 86  are received by attachment apertures  40  of the first and second housing plates  18 , 20 . In this manner, a portion of the first and fifth cylindrical sections  78 , 86  extend from the attachment aperture  40  and are received by the recesses  38 , 39  to prevent the first and fifth cylindrical sections  78 , 86  from extending beyond an outer surface of the housing  12 . 
     It should be noted that the recesses  38 , 39  are designed to incorporate different locations of rivets  76  on the tie bar  14 . Specifically, as the length of the tie bar  14  is adjusted for different seating applications, it is necessary to provide attachment to the housing and accommodate the changing location of the attachment apertures  32 . To prevent the need for new housing  12  tooling for each specific seating application, the recesses  38 , 39  are large enough so that any change in the location of the attachment apertures  32  on the tie bar  14  is accommodated by the housing  12 , as best shown in FIG.  2 . 
     The extension  22  includes the second pivot aperture  37  and an arcuate surface  62 . The second pivot aperture  37  fixedly receives the main pivot  16  for interaction with the tie bar  14 . The main pivot  16  includes a central cylindrical section  64  flanked by first and second cylindrical sections  66 , 68  having a bore  65  formed therethrough. The first and second cylindrical sections  66 , 68  are received by the first and second housing plates  18 , 20  to fixedly attach the main pivot  16  thereto, while central cylindrical section  64  acts as a spacer between the first and second housing plates  18 , 20  and further includes a reaction surface  70  for interaction with the extension  26  of the tie bar  14 . In one embodiment, the seat support structure  10  is pivotably supported by a seat frame in a seatback having a seat bottom attached thereto. In this manner, the central cylindrical section  64  receives a seat structure of the seat bottom such that the seatback pivots relative the seat bottom about the bore  65  of the central cylindrical section  64 . 
     With reference to FIG. 4, the operation of the seat support structure  10  will be described in detail. In one embodiment, the seat support structure  10  is fixedly mounted to a vehicle seat assembly  100 . The vehicle seat assembly  100  includes a seatback  102 , a seat bottom  104 , and a recliner mechanism  106 . The seat support structure  10  can be either mounted directly to the frame (not shown) of a seatback  102  or integrally formed therewith. 
     The seatback  102  is pivotably supported by the seat bottom  104  about the main pivot  16 . Specifically, the seat bottom  104  is received by the bore  65  of the main pivot  16  and as such permits the seatback  102  to rotate relative the seat bottom  104  about the bore  65 . To selectively rotate the seatback  102  relative the seat bottom  104 , a recliner mechanism  106  is provided and is received by pivot  48  to selectively apply a force to the housing  12  causing the seatback  102  to rotate about the main pivot  16 . More particularly, the recliner mechanism  106  locks the seatback  102  in an angular relationship relative to the seat bottom  104  and prevents movement therebetween in a latched position and allows rotation of the seatback  102  in an unlatched position. 
     When the recliner mechanism  106  is in the unlatched position, the seatback  102  is permitted to rotate relative the seat bottom  104  and will do so under a force applied to the seatback  102  either from an occupant or an internal spring (not shown) depending on the direction of the force and the design of the recliner mechanism  106 . In the latched position, the recliner mechanism  106  prevents rotation of the seatback  102  and ensures that the angular relationship of the seatback  102  to the seat bottom  104  is maintained. In this manner, an external force applied to the seatback  102  either by an occupant or a seat-mounted retractor assembly (not shown) causes a load to be applied through the seatback to the recliner mechanism  106  and ultimately to the structure of a vehicle  108 . 
     The seat support structure  10  provides the seatback  102  with a means for transmitting the externally applied load to a structure of a vehicle  108  without deforming the seatback  102 . As a load is applied to the seatback  102 , the extension  26  of the tie bar  14  reacts against the main pivot  16  and provides the housing  12  with adequate stiffness to resist bending of the housing  12  and ultimately the seatback  102 . In this manner, the energy associated with the load is transmitted from the seatback  102  to the housing  12  and eventually to the structure of a vehicle  108 . By transmitting the energy to the vehicle structure  108 , the integrity of the seat assembly  100  is maintained and can perform as designed to protect the occupant under a deceleration condition. 
     In one embodiment, the tie bar  14  is provided with a plurality of adjustment apertures  31  to adjust the overall stiffness of the tie bar  14 . As previously discussed, the stiffness of the tie bar  14  dictates the strength of the housing  12  and ultimately the strength of the seatback  102 . By providing the tie bar  14  with additional apertures, the tie bar  14  can be adjusted or “tuned” to its particular application without having to alter the housing  12 . As can be appreciated, various seat assemblies have varying requirements with respect to seatback  102  stiffness due to the different applications of vehicle seat assemblies  100 . 
     In another embodiment, the tie bar  14  reacts against the main pivot  16  and is designed to deform under a predetermined load to help absorb energy caused by the loading of the vehicle seat assembly  100 . Again, adjustment apertures  31  may be employed in conjunction with a deformable extension  26  to provide the desired stiffness of the seatback  102 . It should be understood that any combination of material selection, material thickness, number of apertures, and length of the tie bar  14  may be used in combination to adjust the overall stiffness of the tie bar  14 . By providing the tie bar  14  with the aforementioned flexibility, the housing  12  can be used interchangeably with various seat assemblies  100 , thereby reducing design and manufacturing costs. 
     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.