Abstract:
A method of fabricating a plurality of seat elements is provided. The plurality of seat elements are styled to have a range of styling features. The method includes a step of determining the range of styling feature by selecting characteristics of a middle ply of foam and/or the exterior ply of the trim cover and selecting a number and position of panels that are sewn to form the trim cover. The seat elements are fabricated on a common mold apparatus.

Description:
[0001]    This application claims the benefits of U.S. Provisional Application No. 60/837,480, filed Aug. 14, 2006. 
     
     FIELD OF THE INVENTION  
       [0002]    The present invention relates to seat assemblies for a motor vehicle. More particularly, the invention relates to a seat element having a foam body bonded with a trim cover. 
       DESCRIPTION OF THE RELATED ART  
       [0003]    A seat assembly includes a seat cushion and seat back for supporting an occupant within a motor vehicle. One method for the fabrication of the each seat element (seat cushion or seat back) includes the formation of a foam body within a trim cover, using a foam-in-place process. This process is well known in the art and fully described in U.S. Pat. Nos. 4,964,794; 5,098,270; 5,107,576; 5,231,746; 5,324,462; 5,466,404; 5,468,434; 5,614,226; and 6,994,812. 
         [0004]    During the process, the trim cover is placed into a mold cavity having a predetermined shape. The mold cavity includes a mold surface defining the mirror image of the supporting surface of the seat cushion or scat back and also any design features to be included on the supporting surface. The material of the trim cover includes an exterior surface ply of fabric, a middle ply of foam material, and an imperforate interior surface ply. The imperforate interior surface ply allows the trim cover to be drawn into conformity with the mold surface by a vacuum. Thereafter, an expandable foam substrate is poured or injected into the mold cavity wherein the foam substrate undergoes a chemical reaction thereby causing the foam substrate to expand, solidify and adhere to the interior surface of the trim cover. 
         [0005]    If a plurality of segments of material is used for the trim cover thereby creating seams, an imperforate tape must be used along the seams in sealed relation with the imperforate interior surface ply. The imperforate tape seals the seams allowing the trim cover to be drawn into conformity with the mold surface by the vacuum without the danger of the vacuum drawing unwanted portions of the foam substrate through the seams between the segments of material, which could result in undesired hard spots in the completed seat cushion or seat back. 
         [0006]    The foam-in-place process has been utilized very successfully for many years for the manufacture of seats for the Chrysler minivan. The disadvantage of the foam-in-place process is that each time a refreshed or new styling is implemented new molds are required to be manufactured. The design and styling features of the seat element are defined by the mold surface; each seat element having different design features requires a different mold, thus adding significant cost to the production 
         [0007]    Further, if different design features are implemented for the same model year, additional molds must be manufactured. If different molds are utilized then the first set of molds must be removed from the production line and a second set of molds must be installed before the seats with a second styling can be produced. With just-in-time delivery to the customer, this staged production requires an inventory of seats to be produced so that there are sufficient stocks of each type of seat available for delivery to the customer. Additional inventory adds costs to the production of the seats. 
         [0008]    Heretofore, leather seats were not suitable for production with a foam-in-place method. To maintain sufficient quality in leather seats, a more traditional method of providing pre-formed foam buns and covering the foam buns with sewn leather covers was utilized. This separate production added costs for the program. 
         [0009]    Therefore, it would be desirable to provide a seat element, and a method of fabricating a seat element, having specific design features determined by the construction of the trim cover itself rather than the mold surface of the mold, enabling a fill range of seating to be manufactured from a single set of tooling. 
       SUMMARY OF THE INVENTION  
       [0010]    According to one aspect of the invention, there is provided a method of fabricating a plurality of seat elements with a common mold assembly comprising an upper mold portion and a lower mold portion. The method comprising the steps of: 
         [0011]    providing a lower mold portion having a lower mold surface contoured to define an occupant support surface between side bolters; 
         [0012]    providing a trim cover having a plurality of panels sewn together, at least one of the panels comprising at least two plies of material including an exterior ply and a middle ply of foam; 
         [0013]    positioning the trim cover onto the lower mold surface; 
         [0014]    applying an imperforate film on the trim cover; 
         [0015]    closing the mold assembly to define a mold cavity therebetween and retain the trim cover relative to said lower mold portion; 
         [0016]    applying a negative pressure between the lower mold surface and the imperforate film so as to conform the trim cover and the imperforate film to the lower mold surface; 
         [0017]    pouring a charge of foam substrate into the mold cavity and allowing the charge to cure and form a foam body and bond at least a portion of the trim cover to the foam body; and 
         [0018]    removing the foam body with the trim cover bonded thereto from the mold cavity. 
         [0000]    The plurality of seat elements are styled to have a range of styling features. The method includes a step of determining the range of styling feature by selecting characteristics of the middle ply of foam and selecting a number and position of the plurality of panels. 
         [0019]    According to another aspect of the invention, there is provided an apparatus for fabricating a plurality of seat elements. The apparatus includes an upper mold portion and a lower mold portion. The upper mold portion being movable relative to said lower mold portion to define a mold cavity therebetween. The lower mold portion has a lower mold surface contoured to define an occupant support surface between side bolters and a ridge between said occupant support surface and each of said side bolsters. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0020]    Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0021]      FIG. 1  is a perspective view of a seat assembly including a seat element having a trim cover according to a first embodiment of the invention; 
           [0022]      FIG. 2  is a perspective view of a featureless foam body for use with the seat element; 
           [0023]      FIG. 3  is a cross-section view of the seat element including the foam body, an imperforate urethane film, and the trim cover; 
           [0024]      FIG. 4  is a perspective view of a mold assembly in an open position; 
           [0025]      FIG. 5  is a perspective view of the mold assembly in the open position including the trim cover and imperforate urethane film laid onto a lower mold surface; 
           [0026]      FIG. 6  is a cross-sectional view of the mold assembly in a closed position; and 
           [0027]      FIG. 7  is a cross-section view of an alternative embodiment of the seat element including the foam body, an imperforate urethane film, and the trim cover. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    Referring to  FIGS. 1 and 2 , a seat assembly for use in a motor vehicle is generally shown at  10 . The seat assembly  10  includes two seat elements, namely a seat cushion  12 , and a seat back  14 . The seat cushion  12  includes a conventional frame structure (not shown) for supporting a foam body  16  having a trim cover  18 . In the preferred embodiment the foam body  16  of the seat cushion  12  is formed with a seating surface  20  between integral side bolsters  22 . 
         [0029]    Similarly, the seat back  14  includes a frame structure (not shown) for supporting a foam body  24  having a trim cover  26 . The frame structure of the seat back  14  is pivotally coupled to the frame structure of the seat cushion  12  for providing selective angular adjustment of the seat back  12  between a plurality of reclined seating positions. In the preferred embodiment the foam body  24  of the seat back  14  is formed with a supporting surface  28  between integral side bolsters  30 . 
         [0030]    The seat elements may be fabricated using the same foam-in-place process as described below. Therefore, while the following description applies to the seat back  14  and the method of fabrication of the seat back  14 , it will be understood that the description also applies to the seat cushion  12  and the method of fabrication of the seat cushion  12 . 
         [0031]    The trim cover  26  includes an occupant-engaging panel  34 , bonded with the supporting surface  28  of the foam body  24 . The occupant-engaging panel  34  includes two segments  38 ,  40  joined together, providing a contrasting appearance along an elongated styling line  42 . In the embodiment shown, the two segments  38 ,  40  are sewn together, although other methods known to one skilled in the art may be used. 
         [0032]    Bolster panels  44  are sewn to the occupant-engaging panel  34  along adjacent vertical edges  46  of the periphery  36  and are also bonded with the integral side bolsters  30  of the foam body  24 . Side panels  48  are sewn to the bolster panels  44  along an exterior edge  50 . A top panel  52  is sewn to the occupant-engaging panel  34  along an upper horizontal edge  54  of the periphery  36  and to the bolster panels  44  along upper edges  56 . 
         [0033]    Referring to  FIG. 3 , a three-ply material  32  forming each panel of the trim cover  26  extends between an exterior surface  58  and an interior surface  60 . An exterior ply  62  of the three-ply material  32  can be a woven fabric, a non-woven fabric, leather, vinyl, or a combination thereof to provide the required color, texture, or both to the exterior surface  58 . 
         [0034]    A middle ply  64  of urethane foam is laminated to the exterior ply  62 . The type, thickness and density of the urethane foam can be selected to vary the degree of comfort that is to be provided. The foam can be closed cell foam, such as memory foam or open cell foam. 
         [0035]    An inner ply  66  of a thermally activated adhesive film is laminated to the middle ply  64  of polyurethane foam. 
         [0036]    An imperforate urethane film  68 , known by its trade name Shawmut, is disposed between the trim cover  26  and the foam body  24 . A single, continuous piece of the imperforate urethane film  68  is disposed between the interior surface  60  of the occupant-engaging panel  34  and the supporting surface  28  of the foam body  24 , and also between the interior surface  60  of the bolster panels  44  and the integral bolsters  30  of the foam body  24 , defining a barrier therebetween. A bond between the inner ply  66  of the trim cover  26 , the imperforate urethane film  68 , and the foam body  24  is established during the foam-in-place process. Alternatively, the imperforate film  68  can be treated so that a portion of the trim cover  26  does not adhere to the foam body  24 . This process enables a portion of the trim cover  26  to float relative to the foam body  24 , which is particularly useful in avoiding wrinkles in the bolster panels  44 , when the exterior ply  52  is leather. 
         [0037]    Alternatively as shown in  FIG. 7 , each panel of the trim cover  26  may include only the exterior ply  62  and the middle ply  64 . In this particular embodiment of the present invention, the imperforate urethane film  68  includes an adhesive surface and is known by its trade name, Bemis. The adhesive surface of the imperforate urethane film  68  is adjacent to the interior surface  60  of the trim cover  26  when the imperforate urethane film  68  is either partially pre-bonded about the periphery  92  to the interior surface  60  of the trim cover  26  or when the imperforate urethane film  68  is laid onto the interior surface  60  of the trim cover  26 . A bond between the middle ply  64  of the trim cover  26 , the imperforate urethane film  68 , and selectively at desired locations, the foam body  24  is established during the foam-in-place process. 
         [0038]    The required panels of the trim cover  26  are sewn together without a bead or welting strip that is common in the prior art. The trim cover  26  and imperforate urethane film  68  are then placed in a mold assembly, generally shown at  70 . As is now apparent, the seam between adjacent panels will create a styling line once the seat element has been formed. Thus, the seat designer has the option of adding or removing styling lines on the seat  10  element merely by adding or removing seams in the trim cover  26 . 
         [0039]    Referring to  FIGS. 2 through 6 , the mold assembly  70  includes a lower mold cast  72  defining a lower mold surface  74  shaped as the mirror image of the supporting surface  28  and integral side bolsters  30  of the foam body  24 . It is important to note that the portion of the lower mold surface  74  for forming the supporting surface  28  of the foam body  24  is relatively featureless. In particular, the mold surface does not have grooves defining a separation line between the side bolsters  30  and the supporting surface  28 . Featureless means that the lower mold cast  72  is configured to the complement of the basic contours of the seat element, namely occupant contact area, supporting surface  28 , between side bolster  30 . A simple smooth ridge or transitional line  75 ,  77  separate the areas that define the supporting surface  28  and the side bolsters  30 . Therefore, any styling or design features to be provided on the seat back  14  are provided by the construction of the trim cover  26  itself. Thus, the mold assembly  70  can be used to fabricate any number of different seat backs  14  by varying the construction of the trim cover  26 , in particular, by varying the design features provided by the trim cover  26 . 
         [0040]    A flexible component  126  is typically a heating unit or occupant sensor, but can be any component required to be included within the seat back  14 . The heating unit  126  is molded-in-place between the supporting surface  28  of the foam body  24  and the imperforate urethane film  68 . The heating unit  126  includes wires (not shown) extending from the seat back  14  for controlling the heating unit  126 . The heating unit  126  also includes an adhesive surface  128  adjacent to the imperforate urethane film  68  for adhering the heating unit  126  to the imperforate urethane film  68  at the desired location within the periphery  36  of the occupant-engaging panel  34 . The heating unit  126  may be adhered to the imperforate urethane film  68  using the adhesive surface  128  prior to, or subsequent to, laying the trim cover  26  and imperforate urethane film  68  onto the lower mold surface  74  of the mold assembly  70 . Since the heating unit  126  is flexible the source of vacuum draws the trim cover  26 , imperforate urethane film  68 , and heating unit  126  into conformity with the lower mold surface  74 . The adhesive surface  128  maintains the heating unit  126  at the desired location during the foam-in-place process and prevents the heating unit  126  from floating in the foam substrate before the foam substrate cures to form the foam body  24 . The foam substrate fills the mold cavity  88  and is cured to form the foam body  24 , resulting in the heating unit  126  being molded-in-place. 
         [0041]    The lower mold cast  72  includes an interior passage or manifold system, generally indicated at  76 , which communicates between the lower mold surface  74  and a vacuum source through a series of openings  78  extending therethrough. It will also be noted that the lower mold cast  72  includes an outer peripheral surface  80  surrounding the lower mold surface  74 . 
         [0042]    Mold assembly  74  also includes an upper mold cast  82  defining a substantially flat upper mold surface  84 . The upper mold cast  82  is mounted for pivotal movement between an open position, shown in  FIG. 4 , and a closed position, shown in  FIG. 6 , in which a peripheral surface  86  surrounding the upper mold surface  84  is in sealing engagement with the peripheral surface  80  surrounding the lower mold surface  74 . In the closed position, the upper mold cast  82  and lower mold cast  72  define a mold cavity  88  therebetween, wherein the foam-in-place process takes place. The upper mold cast  82  includes at least one foam substrate injector  90  extending through the upper mold cast  82  so as to communicate with the mold cavity  88  when the upper mold cast  82  is in the closed position. 
         [0043]    A plurality of heat lines (not shown) within the upper mold cast  82  and the lower mold cast  72  are disposed adjacent to the respective upper and lower mold surfaces  84 ,  74  for providing heat to the mold cavity  88  during the foam-in-place process. The reaction that the foam substrate undergoes during the foam-in-place process in the mold cavity  88  is an exothermic reaction, which produces heat during the foam-in-place process. 
         [0044]    Prior to laying the trim cover  26  and imperforate urethane film  68  onto the lower mold surface  74  of the mold assembly  70 , as shown in  FIG. 5 , the imperforate urethane film  68  may be partially pre-bonded about a periphery  92  of the imperforate urethane film  68  to the interior surface  60  of the trim cover  26 . Pre-bonding the imperforate urethane film  68  to the trim cover  26  allows for ease of material handling and reduces the cycle time for loading the trim cover  26  and imperforate urethane film  68  onto the mold assembly  70 . 
         [0045]    With the upper mold cast  82  in the open position, a mold release agent, as is well known to one skilled in the art, is sprayed onto the upper and lower mold surfaces  84 ,  74  for preventing the trim cover  26  and the foam body  24  from sticking to the upper and lower mold surfaces  84 ,  74  after the foam-in-place process is complete. Subsequent to applying the mold release agent, the trim cover  26  with the imperforate urethane film  68  partially pre-bonded thereto is laid onto the lower mold surface  74  with the exterior surface  58  of the trim cover  26  adjacent to the lower mold surface  74 . Alternatively, if the imperforate urethane film  68  is not partially pre-bonded to the interior surface  60  of the trim cover  26 , the trim cover  26  is first laid onto the lower mold surface  74  with the exterior surface  58  adjacent to the lower mold surface  74  and then the imperforate urethane film  68  is laid onto the interior surface  60  of the trim cover  26 . 
         [0046]    A source of vacuum (not shown) is communicated with the manifold system  76  to create a negative pressure condition between the lower mold surface  74  and the imperforate urethane film  68 , which draws the occupant-engaging panel  34  and bolster panels  44  of the trim cover  26  into conformity with the lower mold surface  74 . The negative pressure also causes any design features and seams provided by the construction of the trim cover  26  to compress into conformity with the lower mold surface  74 . Thereafter, the upper mold cast  82  is moved into the closed position, in which the peripheral surface  86  surrounding the upper mold surface  84  is in mating engagement with the peripheral surface  80  surrounding the lower mold surface  74 , creating the mold cavity  88  therebetween. Panels of the trim cover  26  which are not bonded with the foam body  24  during the foam-in-place process extend from the mold cavity  88  and are disposed between the peripheral surface  86  surrounding the upper mold surface  84  and the peripheral surface  80  of the lower mold surface  74 . In the embodiment shown, the occupant-engaging panel  34  and the bolster panels  44  are disposed within the mold cavity  88  for bonding with the foam body  24  during the foam-in-place process. The side panels  48  and top panel  52  extend from the mold cavity  88  and therefore will not be bonded with the foam body  24 . 
         [0047]    Next, a charge of the foam substrate is injected through the foam substrate injector  90  into the mold cavity  88 . The mold cavity  88  is heated by circulating heated fluid through the plurality of heat lines within the upper and lower mold casts  82 ,  72 . The heat and pressure from the mold assembly  70  initiates a chemical reaction of the foam substrate causing the foam substrate to fill the mold cavity  88 , thereby forming the foam body  24 . At the same time, the heat and pressure from the mold assembly  70  and the heat produced by the exothermic chemical reaction of the foam substrate causes the inner ply  66 , or alternatively the middle ply  64 , of the trim cover  26 , the imperforate urethane film  68 , and the foam body  24  to bond together. 
         [0048]    After the foam body  24  has cured, the upper mold cast  82  is moved into the open position and the seat back  14  including the trim cover  26  bonded with the foam body  24  is removed from the mold assembly  70 . The removal of the seat back  14  from the lower mold surface  74  allows any previously vacuum-compressed design features provided by the construction of the trim cover  26  to recover to their original shape. The side panels  48  and top panel  52  are then wrapped around the foam body  24  and fixedly secured thereto. Alternatively, the side panels  48  and top panel  52  are wrapped around the foam body  24  and a back panel (not shown) is sewn to the side panels  48  and top panel  52 , enclosing the foam body  24  within the trim cover  26 . It will be understood that, after the seat back  14  has been completed in the manner described above, it is then mounted to the frame structure and secured in its operative position. 
         [0049]    The invention has been described in an illustrative manner. It is to be understood that the terminology, which has been used, is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.