Abstract:
A seat assembly includes a hinge assembly having a linear adjustment mechanism including a recliner rod slidably supported by a housing and a pawl rotatably supported by the housing. The recliner rod preferably has a toothed portion that interfaces with a toothed portion of the pawl to prohibit the recliner rod from sliding. The pawl is pivotable relative the housing such that it may be disengaged to enable the recliner rod to slide freely. When the pawl engages the recliner rod in a locked position, a first force component generally normal to the engagement of the pawl and the recliner rod and a second force component generally through the pawl pivot reduce play and improve the load-carrying capacity of the linear adjustment mechanism.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to recliner assemblies for seats and more particular to an improved linear recliner assembly for reducing undesirable movement when the assembly is locked. 
     BACKGROUND OF THE INVENTION 
     Occupant safety and comfort are paramount concerns for automobile manufacturers. In particular, vehicle seating systems are a significant focus for improved comfort and safety even as manufacturers add more functions and improve versatility of seat assemblies. For example, conventional vehicle seating systems include reclining seats that enable comfort adjustment by a vehicle occupant. As more functions and features are added, manufacturing a reliable, safe, and cost-effective seat assembly becomes an increasing challenge. 
     In many reclining seats, a linear recliner mechanism includes a recliner rod that reciprocates relative a recliner mechanism housing. The reciprocating recliner rod is pivotally connected at one end to a long lever arm, usually the seatback, against which various forces are applied. The linear recliner mechanism in a vehicle seat is quite small when compared with the length of a seatback, and vehicle vibration or movement of an occupant may impose various forces upon that lever arm during use. Because these forces are applied along such a lengthy lever arm, a large moment is imposed about the recliner rod&#39;s pivotal connection to the lever arm, whereby the effects of any variations in the components of the recliner mechanism are magnified. Such play or backlash between the engaging teeth or clearances in the mechanism components allow the seatback to move a miniscule amount even when the mechanism is locked. These small excursions are magnified by the length of the lever arm and become noticeable at the upper end of the seatback. For example, the seatback of an unoccupied seat may tend to oscillate When the vehicle encounters rough road conditions. This magnified play in a recliner mechanism has been termed “chucking” and refers to any manufacturing variation or play in the mechanism components that allows movement of the lever arm or seatback while the mechanism is in a locked condition. 
     Additionally, as seat assemblies have been improved by automobile manufacturers, increased seatback loading has resulted from seatbelt systems attached to a top portion of the seatback. In the event of an accident, the forward inertia of an occupant&#39;s body pulls the seatbelt with an extremely large force. Such a large force on the seatback, acting as a lever arm, results in a significant strain within. the recliner mechanism. As a result, recliner mechanisms used with such “all belts-to-seat” applications (i.e., stand-alone structural seats.) must be sufficiently strong to protect and restrain an occupant during a crash. 
     Further, as seat assemblies have evolved to include more functions and a greater range of motion, packaging has become a concern. When including a linear recliner mechanism in a seat assembly, a recliner rod that reciprocates relative to the recliner mechanism housing is preferred over a threaded rod that rotates a nut relative the recliner mechanism housing because of these packaging concerns. Also, in such linear recliner mechanisms, an expansion spring is usually mounted coaxially with the recliner rod to bias the seatback to its upright position. Expansion springs generally increase the recliner rod length and limit the packaging options. Further, increased recliner rod length reduces the compressive strength of the recliner rod based upon the principle of column loading. 
     Therefore, it is desirable in the industry to provide a recliner mechanism that significantly reduces or eliminates chucking of a seat assembly. It is further desirable that such a recliner mechanism be sufficiently strong, providing adequate occupant protection in the event of an accident. 
     SUMMARY OF THE INVENTION 
     Generally, the present invention provides an improved linear adjustment mechanism for implementation with a recliner mechanism of a seat assembly. The linear adjustment mechanism directs the forces within the locking mechanism to reduce the overall clearances within the recliner mechanism. One advantage of the present invention is the reduced clearances translate into reduced chucking of the seatback relative to the seat. As a result, overall occupant comfort and safety is increased. Another advantage of the present invention is the improved crash performance of the seat assembly. The linear recliner mechanism&#39;s directed forces result in increased strength of the locking members, such that the seatback maintains its position relative to a seat in the event of an accident. This is especially desirable with seatback-mounted seatbelt systems. 
     To achieve the above described advantages, the present invention provides a linear adjustment mechanism including a bar rack slidably supported in a housing having inner and outer plates. A pawl is pivotably supported between the inner and outer plates for selectively locking the bar rack in one of a plurality of positions relative to the pawl. The pawl is disposed substantially parallel to the bar rack such that in a locked position a linear force applied to the bar rack produces a resultant linear force to the pawl, wherein clearances between the pawl and a pivot of the pawl are reduced. 
     In a preferred embodiment of the present invention, the linear adjustment mechanism is included in a seat assembly having inner and outer supports and an arm supporting a seatback and rotatably mounted between the inner and outer supports. The arm pivotally interfaces the bar rack such that the arm, and thus the seatback, can be positioned in a plurality of rotatable positions relative to the inner and outer supports, as well as the seat bottom, corresponding to the plurality of positions of the bar rack. Preferably, a return spring biases the arm, and thus the seatback, in a first position corresponding to a dump position of the seatback. Further, the return spring minimizes the length of the bar rack, thus maximizing its column loading strength. 
     Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various advantages of the present invention will become apparent to those skilled in the art by reading the following specification and reference to the drawings in which: 
     FIG. 1 is a perspective view of a linear adjustment mechanism according to the present invention; 
     FIG. 2 is an exploded view detailing individual components of the linear adjustment mechanism of FIG. 1; 
     FIG. 3 is a side view of the linear adjustment mechanism of FIGS. 1 and 2 in a locked position; 
     FIG. 4 is a perspective view of a seat assembly implementing control-and-remote side linear recliner assemblies according to the present invention; 
     FIG. 5 is a schematic view illustrating the relationship of the linear recliner assemblies of FIG. 4; and 
     FIG. 6 is a side view of the control-side linear recliner assembly of the seat assembly of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIGS. 1 and 2, a linear adjustment mechanism  10  will be described in detail. The linear adjustment mechanism  10  generally includes inner and outer plates  12 , 14 , a recliner rod or bar rack  16 , a pawl  18 , inner and outer cam plates  20 , 22  and a spindle  24 . 
     The inner and outer plates  12 , 14  slidably support the bar rack  16  and pivotally support the pawl  18 . More particularly, first and second bar supports  26 , 28  are supported between the inner and outer plates  12 , 14  for slidably supporting the bar rack  16  therebetween. Additionally, the inner plate  12  forms an upper bar support  30  for guiding a top face  32  of the bar rack  16 . The inner and outer plates  12 , 14  further include vertically disposed inner and outer pawl pin slots  36 , 38 , respectively for guiding the pawl  18  with respect to the cam plates  20 , 22 . 
     The pawl  18  is pivotally supported on a first end by a pawl rivet  34  extending between the inner and outer plates  12 , 14  and is positioned above and generally parallel to the bar rack  16 . The bar rack  16  includes a toothed portion  40  that selectively interfaces with a toothed portion  42  of the pawl  18 , which moves between engaged and disengaged positions. The bar rack  16  further includes an aperture  44  for pivotally connecting to a support arm  114  of a seatback, as will be described below. The pawl  18  selectively locks the bar rack  16  to prohibit sliding movement of the bar rack  16  between the inner and outer plates  12 , 14 . The toothed portions  40 , 42  of both the pawl and the bar rack  16  are configured such that the teeth are numerous and small. As a result, the pawl  18  and bar rack  16  engagement is capable of fine adjustment. 
     The inner cam plate  20  is pivotally supported between the inner and outer plates  12 , 14  on the inner plate side of the pawl  18  and includes an inner cam slot  46  and a keyed slot  47 . The inner cam plate  20  also has a cable mount  48  formed in an upper portion. The outer cam plate  22  is pivotally supported between the inner and outer plates  12 , 14  on the outer plate side of the pawl  18  and includes an outer cam slot  50  and a keyed slot  51 . The inner and outer cam slots  46 , 50  are identical in form (generally peanut-shaped) and run at an angle on the inner and outer cam plates  20 , 22  (see FIGS.  2  and  3 ). The inner and outer cam plates  20 , 22  are supported on, and fixed for rotation with, the spindle  24  through reception of the spindle  24  in the keyed slots  49 ,  51 . 
     The spindle  24  is mounted in spindle holes  25 , 27  which, rotatably support the spindle  24  between the inner and outer plates  12 , 14 . A first end of the spindle  24  includes a spring groove  52  for securing a biasing member or cam return spring  54 . The cam return spring  54  is a coil-type spring commonly known in the art, however, other springs such as linear, can be substituted therefor. An inner end  55  of the cam return spring  54  is secured by the spring groove  52  of the spindle  24  and an outer end of the cam return spring  54  is secured by a spring holder  56  formed on the inner plate  12 . The cam return spring  54  biases the spindle  24  in a first rotational direction (counter-clockwise as shown in FIG.  3 ), thus biasing inner and outer cam plates  20 , 22  in the first rotational direction. A second end of the spindle  24  includes a splined portion  58  (best shown in FIG. 1) for securing a handle, as will be described below. Preferably, the handle is pulled upwardly by an operator for rotating the spindle  24  against the biasing force of the cam return spring  54 . A pair of keyed shoulders  57 ,  59  are disposed intermediately along the spindle  24 . The keyed shoulders  57 ,  59  respectively register in the keyed slots  47 ,  51  of the inner and outer cam plates  20 ,  22  to cause rotation of the inner and outer cam plates  20 ,  22  with the spindle  24 . 
     The pawl  18  is pivotally mounted at a first end by the pivot pin  34  and supports a pawl pin  60  in an aperture  19  at a second end. The pawl pin  60  extends through the inner and outer cam slots  46 , 50  of the inner and outer cam plates  20 , 22 . As such, the pawl pin  60  is slidable along the generally peanut-shaped inner and outer cam slots  46 , 50 . Additionally, the pawl pin  60  includes reduced-diameter outer ends slidably supported in the inner and outer pawl pin slots  36 , 38  of inner and outer plates  12 , 14 . The position of the pawl pin  60  in the cam slots  46 ,  50 , dictates the position of the pawl  18 . Due to the rotational biasing force exerted by the cam return spring  54 , the inner and outer cam plates  20 , 22  bias the pawl pin  60 , and thus the pawl  18 , toward the engaged position, forcing the pawl  18  into meshed engagement with the bar rack  16 . 
     To achieve almost zero free-play in the linear adjustment mechanism  10  the clearances in the pawl  18  and pawl rivet.  34  interface must be eliminated. According to the present invention, this is accomplished through the novel configuration of the linear adjustment mechanism  10 . With particular reference to FIG. 3, the inner and outer cam plates  20 , 22  are rotatable about an axis ‘A’ of the spindle  24  and the pawl  18  is rotatable about an axis ‘B’ of the pawl rivet  34 . As described above, the inner and outer cam plates  20 , 22  are biased in a counter-clockwise direction by the cam return spring  54 . As such, the cam surface of the inner and outer cam slots  46 , 50  bias the pawl pin  60  toward the bar rack  16 . The force exerted through the cam surface of the inner and outer cam slots  46 , 50 , against the pawl pin  60 , can be traced from a center point ‘C’ of the pawl pin  60  and is designated by a vector ‘V’. The vector V is directed toward the pivot point A and is made up of component vectors ‘X’ and ‘Y’. Accordingly, any free-play (causing the aforementioned seatback chucking) associated with pivot point A is eliminated. As will readily be appreciated by those skilled in the art, component force vector X is directed substantially toward pivot point B. Consequently, any free-play (causing the aforementioned seatback chucking) associated with pivot point B is eliminated. Additionally, the ‘Y’ component force vector is directed generally perpendicular to the interface between the pawl  18  and the bar rack  16 , thereby ensuring that the toothed portion  42  of the pawl  18  firmly meshes with the toothed portion  40  of the bar rack  16 . The biased cam plates  20 , 22  have increased leverage to resist any separating force of the pawl  18 , thereby increasing the load carrying capacity of the linear adjustment mechanism  10 . 
     With reference to FIGS. 3 through 6, the implementation of the linear adjustment mechanism  10  in a linear recliner assembly of a seat assembly  100 , will be described in detail. As shown, the seat assembly  100  includes a seatback  102 , a seat  104 , and both control and remote side linear recliner assemblies  106 , 106 ′ each including a linear adjustment mechanism,  10 , 10 ′ for selectively reclining the seatback  102  relative to the seat  104 . It should be noted that control and remote side linear recliner assemblies  106 , 106 ′ are nearly identical in construction and, therefore, like reference numerals will be used to describe identical components of each. However, reference numerals describing the remote side linear recliner assembly  106 ′ will include a prime (′) symbol. 
     There is one notable distinction between the control and remote side linear recliner assemblies  106 , 106 ′. The inner and outer cam slots  46 ′, 50 ′ of the remote side linear adjustment mechanism  10 ′ run across the inner and outer cam plates  20 ′, 22 ′ at an angle opposite to that previously described for the inner and outer cam slots  46 , 50  of the control side linear adjustment mechanism  10 . This is best shown in FIG. 5, which shows both the control side inner cam plate  20  and the remote side inner cam plate  20 ′. As a result when the pawl  18  of the control side is released by rotating the inner and outer cam plates  20 , 22  in a first rotational direction (clockwise as shown), the pawl  18  of the remote side is released by rotating the inner and outer cam plates  20 ′, 22 ′ in a second opposite direction (counter-clockwise as shown). 
     The linear recliner assemblies  106 , 106 ′ each include inner and outer supports  110 , 110 ′ and  112 , 112 ′, respectively, and arms  114 , 114 ′ pivotally supported between the inner and outer supports  110 , 110 ′, 112 , 112 ′ about a first pivot axis Q. Arm return springs, 116 ′ 116 ′ which. are preferably coil springs, pivotally bias the arms  114 , 114 ′, in a first rotational direction about the first pivot axis Q. Further, both the control and remote side linear recliner assemblies  106 , 106 ′ include linear adjustment mechanisms  10 , 10 ′, as noted above. A bottom portion of each arm  114 , 114 ′ is pivotally attached to an end of the respective bar rack  16 , 16 ′ about a second pivot axis R at the aperture  44 , 44 ′ of each bar rack  16 , 16 ′. The control side linear recliner assembly  106  also includes a handle  118  attached to the splined portion  58  of the linear adjustment mechanism  10  for actuating the inner and outer cam plates  20 , 22 . Additionally, a cable  120  is attached to the cable mount  48  of the inner cam plate  20  of the control side linear adjustment mechanism  10 . and runs around a bottom surface of the seat  104  for linking with the cable mount  48 ′ of the inner cam plate  20 ′ of the remote side linear adjustment mechanism  10 ′. 
     With particular reference to FIGS. 3 and 6, operation of the seat assembly  100  will be described in detail. At the outset, the seatback  102  rests at a reclined position relative to the seat. An alternative reclined position of the seatback  102  relative to the seat  104  may be achieved by an operator pulling the handle  118 . in a clockwise direction. As described previously, clockwise rotation of the handle  118  results in clockwise rotation of the control side inner and outer cam plates  20 , 22  against the bias of spring  54 . As a result, the control side pawl pin  60  is biased upward by the inner and outer cam slots  46 , 50 , thus pulling the pawl  18  out of engagement with the bar rack  16 . Concurrently, the cable  120  is pulled as a result of the clockwise pivoting of the inner cam plate  20 . The cable  120  subsequently pulls on the remote side inner cam plate  20 ′, thus causing counter-clockwise rotation of the remote side inner and outer cam plates  20 ′, 22 ′ against the bias of spring  54 ′. As a result, the counter-clockwise rotation of the remote side inner and outer cam plates  20 ′, 22 ′ causes disengagement of the remote side pawl  18 ′ with the bar rack  16 ′. 
     With both the control and remote side bar racks  16 , 16 ′ out of locking engagement with the pawls  18 , 18 ′, the seatback  102  is free to pivot about first pivot axis Q. Due to the biasing force of each arm return spring  116 , 116 ′ the arms  114 , 114 ′ pivot in the first rotational direction (counter-clockwise as shown), whereby the seatback  102  moves toward a dumped position. To achieve pivoting of the arms  114 , 114 ′ in an opposite rotational direction (clockwise) an operator must apply a counter-biasing force greater than the biasing force of the arm return springs  116 , 116 ′. As the arms  114 , 114 ′ of the control and remote side linear recliner assemblies  106 , 106 ′ are caused to pivot, the respective bar racks  16 , 16 ′ slide accordingly. The seatback  102 , being attached to both arms  114 , 114 ′ of the linear recliner assemblies  106 , 106 ′, can be locked at a desired recline position by releasing the handle  118  of the control side linear recliner assembly  106 . Once the handle is released, the inner and outer cam plates  20 , 22  of the control side rotate counter-clockwise due to the biasing force of the cam return spring  54 . As such, tension is relieved from the cable  120  and the remote side inner and outer cam plates  20 ′, 22 ′ rotate clockwise, with the biasing force of the cam return spring  54 ′. As a result, both the control and remote side bar racks  16 , 16 ′ again achieve locked engagement with their respective paws  18 , 18 ′ and the seatback  102  is held in the desired recline position. 
     The novel configuration of the seat assembly  100 , and particularly the linear adjustment mechanism  10 , 10 ′ serves to virtually eliminate any clearances between the various components. As such, chucking of the seatback  102  relative to the seat  104  is greatly reduced, enhancing overall occupant comfort. The novel configuration also results in increased strength of the overall seat assembly  100  enhancing crash performance. 
     While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the description of the appended claims.