Abstract:
An efficient method for making a vehicle seat. A vehicle seat is molded in a mold set which includes a base element and a series of upper elements with the cover supported in the mold cavity and layers of resins being molded thereon. The resultant seat, which is particularly well-suited for use on motorcycles, includes a cover, a cellular cushioning layer self-bonded directly to the cover, a generally ring-shaped support element disposed on the cellular cushioning layer, and a seat base layer self-bonded directly to the cellular cushioning layer and the skirt portion of the cover layer.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to vehicle seats, and more particularly to a multi-layer vehicle seat that is made and assembled without requiring adhesives. The invention also relates to a method of making such vehicle seats. 
     Seats for vehicles such as motorcycles usually have a supporting base layer, a cushion layer, and an exterior cover layer. Traditionally, a molded cushion is formed on the base layer and a cover is stitched and fitted over the cushion. While seats of this type are high in quality and have excellent durability, it would be useful to develop a seat of similar quality which can be formed more efficiently. 
     It is an object of the invention to provide a novel method for making a durable vehicle seat at a reduced production cost. 
     Another object is to provide a vehicle seat that can be fabricated without the use of adhesive coatings. 
     A further object is to provide a method for a high quality vehicle seat that can be molded using a mold set comprised of a base mold and a multiplicity of separate upper molds. 
     Yet another object is to provide a method of making a vehicle seat which results in minimal emissions of volatile oxygen compounds (VOCs). 
     SUMMARY OF THE INVENTION 
     It has now been found that the foregoing and related objects may be readily attained in a novel method of making a vehicle seat. The method comprises the steps of providing a seat mold having a lower element, and a plurality of upper elements, applying a seat cover to the surface of the lower element of the seat mold, the seat cover including a seating portion and a skirt portion extending upwardly along the inside periphery of the lower element of the mold and outwardly thereof, introducing a first foamable synthetic resin into the lower element on the seating portion of the seat cover, interfitting a first upper element of the seat mold on the lower element, and at least partially curing the first foamable synthetic resin to form a cushioning layer. The first upper mold element is removed, and a generally ring-shaped support element is formed on the cushioning layer about its periphery. The skirt portion of the seat cover is then folded inwardly over the generally ring-shaped support element, and a second synthetic resin is introduced into the lower element of the seat mold on the first foamable synthetic resin. A second upper mold element of the mold is interfitted on the lower element of the mold, and the second synthetic resin is cured to produce the seat base layer. Any additional curing required for the first synthetic resin takes place simultaneously. The vehicle seat is then removed from the mold. 
     Preferably, the generally ring-shaped support layer is reaction injection molded directly onto the cushioning layer. The step of forming a generally ring-shaped support layer preferably includes the steps of interfitting a ring-forming upper mold element on the lower element of the seat mold, injecting a reaction injection moldable resin into the mold between the ring-forming upper element and the cushioning layer, and removing the ring-forming upper element. The reaction injection moldable material bonds to the cushion layer during reaction. 
     In one preferred form of the invention, the second upper element has hardware receiving cavities therein in which are placed seat hardware. In this embodiment, the step of interfitting the second upper mold element on the lower element of the mold embeds the seat hardware into the second synthetic resin. 
     Thus, it can be seen that vehicle seat has the cellular cushioning layer self-bonded directly to the cover, and the generally ring-shaped support element disposed adjacent to the cushioning and is self bonded to it. The seat base layer self-bonded directly to the cushioning layer and to the generally ring-shaped support element and the skirt portion of the cover. 
     The cushioning layer preferably comprises a foamed thermoset resin, and more preferably comprises a thermosetting polyurethane. The seat base layer preferably comprises a thermosetting resin. Desirably, the cover layer comprises natural leather, a synthetic resin sheet material or canvas. 
    
    
     Other features of the present invention, including the methods and operation, related elements of the structure, combination of parts and economics of manufacture will become apparent upon consideration of the following description and claims with reference to the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a motorcycle seat according to the invention, which is the seat being broken apart and in partial cross section to show the interior structures; 
     FIG. 2 is a cross sectional view of a lower mold element used to form the motorcycle seat according to the present invention; 
     FIG. 3 is a similar view of the lower mold element in partially section to view a vacuum system used to position a sheet of cover material thereon; 
     FIG. 4 schematically shows the step of dispensing a foamable synthetic resin into the lower element of the mold; 
     FIG. 5 schematically shows the lowering of a first upper element of the mold onto the lower mold element; 
     FIG. 6 schematically shows the step of curing the foamable synthetic resin to form a cellular cushioning layer; 
     FIG. 7 schematically shows the lowering of a ring-forming upper mold element onto the lower mold element; 
     FIG. 8 schematically shows the step of reaction injection molding the support element; 
     FIG. 9 schematically shows the mold with a second upper element having hardware supported therein; 
     FIG. 10 schematically shows injection molding of the seat base; 
     FIG. 11 schematically shows the ejection of the finished seat by air pressure; and 
     FIG. 12 schematically illustrates an alternative embodiment of a lower mold element to produce a contoured seat cover. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning first to FIG. 1, a vehicle seat embodying the present invention is generally designated by the numeral  10 . The seat  10 , which preferably is a motorcycle seat, includes a seat base layer or platform member  12  that is configured to be secured to the frame or chassis of a motorcycle by brackets  14 ,  15 . The seat base layer  12  is formed from a strong, moldable resin, preferably a polyurethane. A support ring shaped element  16  extends around the perimeter of the seat  10  on the seat base layer  12 . The support ring  16  provides the seat with structural integrity and supports a cushioning layer  18 . The cushioning layer  18  extends across the top and sides of the seat  10  and provides comfort to the rider. The cushioning layer  18  is formed from a resiliently deflectable cellular foamed synthetic resin or any other moldable, resiliently deformable foam material. The seat base layer  12  is self-bonded directly to the cushioning layer  18 , i.e., without the use of a separate adhesive layer. 
     An exterior cover  20  surrounds the cushioning layer  18  and is made of a durable, weather-resistant material such as natural leather, synthetic leather such as a mixture of synthetic fiber and polyurethane, canvas, or other synthetic resin sheet material, a thermoplastic. The cover  20  includes a seating portion  22  configured to support the rider and a skirt portion  23  which is folded around the support element. 
     When the seat  10  is designed for a motorcycle, it preferably is saddle-shaped, and includes a seating area  24  with a rearward concave area  25 , a forward convex area  26 , and a back portion  28 . A pair of side panels  30  extend downwardly from the seating area  24 . 
     In fabricating and assembling the vehicle seat  10 , a mold set  100  having a lower element  102  and several upper elements is employed. The lower element  102 , shown in FIG. 2, includes a first part  104  and a second part  106  that are horizontally disposed and abut one another. The first part  104  has a lower vacuum/pressure line  108  and an upper vacuum/pressure line  116 . Each line is connected to a plurality of air channels  112 , disposed within the first part  104 , shown in FIG.  3 . The second part  106  has a lower vacuum/pressure line  110  and an upper vacuum/pressure line  118 . Similarly, a plurality of air channels (not shown) are disposed within the second part  106  and are connected to lines  110  and  118 . 
     As is shown in FIG. 3, in the first step of the process of the invention, the first and second parts  104 , 106  of the lower element are closed together and the vacuum in lines  108 , 110  is turned on. The pre-cut exterior cover  20  is placed on the lower element  102 . The seating portion  22  is placed within the mold cavity of the lower element  102 , and the surrounding skirt portion  23  extends outwardly from the mold cavity of the lower element  102 . 
     As is illustrated in FIG. 4, a foamable first resin composition  120 , used to form the cushioning layer  18 , is dispensed into the lower element  102  through a nozzle  124 . The resin composition  120  preferably is a castable polyurethane containing a blowing or foaming agent, but foamable synthetic resins may be employed. Subsequently, as is shown in FIGS. 5 and 6, a first upper element  126  of the mold is placed on the lower element  102 . The first upper element  126  has a pair of air inlet lines  128  through which air is introduced to push the skirt portion  23  outwardly as the first upper element  126  is lowered. The first resin composition  120  is subjected to the desired heat cycle to expand the synthetic resin to form the foamed cushioning layer  18 . During curing, the first resin composition  120  chemically and mechanically bonds to the inner surface of the cover  20  and will hold the cover material in the shape of the mold cavity after the seat  10  has been removed from the mold. 
     After the first resin composition  120  is substantially cured, the first upper element  126  is removed and the support ring  16  is formed on the cushioning layer  18 . In one embodiment, a preformed support ring  16  made of polyurethane, or another suitable thermoset or thermoplastic material, is placed on the cushioning layer  18  and the lower element  102 . However, in the preferred embodiment as illustrated in FIGS. 7-8, the support ring  16  is formed in the mold. More particularly, a ring-forming upper element  136  is placed on the lower element  102 . When the mold is closed, a ring-shaped cavity is defined by part of the top surface of cured first resin composition  120  and by walls  137 ,  138  of the ring forming element  136 . A reaction injection moldable resin  142  is then injected into the closed mold through a plurality of ring material inlet lines  140  in the second upper element  136 . The reaction injection moldable resin  142  is one which will form a durable ring upon curing. In a particularly preferred form of the invention, this material is a thermosetting polyurethane. The reaction injection moldable material  142  chemically and mechanically bonds to the cushioning layer  18  during reaction. 
     The ring-forming upper mold element  136  is subsequently removed and a base-forming upper element  144  is now coupled to the lower element in order to form the seat base. The base-forming upper element  144  has cavities therein in which are seated a pair of supports  146 ,  147  for supporting brackets  14 ,  15 . The ends of brackets  14 ,  15  which are to be encapsulated in the seat base layer  12  extend downwardly from the base-forming upper mold element  144 , as is shown in FIG.  9 . 
     After the base-forming upper element  144  secured to the lower element  102  as is shown in FIG. 10, a seat base resin  150  is injected into the mold through a plurality of injection lines  152  which are formed in the base-forming upper element  144 . After injection, the seat base material  150  chemically and mechanically bonds to the cushioning layer  18  and inner edge of the support ring  16 . The seat base material  150  is a rigid, high modulus moldable material, and preferably is an injection moldable material. Suitable resins include polyurethanes, epoxy and polyesters, with or without fillers or reinforcing fibers. It is noted that the seat base resin alternatively can be injection or compression moldable so long as an appropriate type of base-forming upper mold element is used. 
     In the particularly preferred embodiment of the invention shown in FIGS. 9 and 10, the skirt portion  23  of the exterior cover  20  is folded inwardly before the base-forming upper element  144  is lowered. Preferably, the skirt portion  23  is folded manually, or by injecting air inwardly through lines  116 ,  118 . The seat base material  150  covers the skirt portion, thereby holding the skirt portion in place around the support ring  16 . Alternatively, the seat base material  150  can be applied in two layers and the skirt portion  23  can be folded inward after application of the first layer in order to sandwich it between the two layers. 
     After curing of the seat base resin  150 , the base-forming upper mold element  144  is removed and the first and second parts  104 ,  106  of the lower elements  102  are separated. Air pressure optionally is used in lines  108 ,  110  the lower element  102  to eject the vehicle seat  10  from the mold. The completed vehicle seat  10  is ready for installation on the motorcycle using brackets  14 ,  15 . 
     An alternative embodiment of the lower element of the mold is shown in FIG.  12  and is designated as  102 . The inner mold surface has a patterned surface with embossing areas  154  which effectively emboss the outer surface of the seat base layer  12  during the molding process. The flexible foam of the cushioning layer mechanically and chemically bonds to the cover  20  when the cover  20  is pressed in the protrusions  154 , causing the cover  20  to retain indentations  156  corresponding to the protrusions  154  upon removal from the mold set  100 . As is well known, the mold elements can be heated by a heat exchange fluid or by resistance hiatus included therewithin. 
     Thus, it can be seen from the foregoing detailed specification and attached drawings that the method of the present invention provides a high quality vehicle seat that can be made efficiently using a single mold set. All operations are performed using the same lower mold element and a series of upper mold elements which cooperate therewith. Excellent shape retention of the cushioned seat is obtained by molding the cushioning layer  18  directly onto the cover  20 . Reaction injection molding of the support ring, resulting in chemical and mechanical bonding of the ring to the cushioning layer  18 , contributes to the durability of the seat. The skirt portion or cover layer is effectively held in place by sandwiching it within the base layer. Encapsulation of the brackets into the seat base layer further contributes to the stability of the resulting vehicle seat.