Abstract:
The subject invention is an apparatus and method for installing a cushion into a cover to provide for a uniform and consistent thickness of cushion between an inflator/horn assembly and the cover such that variation in the amount of force applied to the cover is minimized. The apparatus for installing the cushion to the cover includes a base for supporting the cover, a housing defining a cavity and having an upper and a lower platform, an air bag housing and a mock inflator attached to a piston. The method includes the steps of attaching the cushion assembly to a mock inflator, securing the cover, compacting the cushion into the cover and around the mock inflator, such that the cushion fills the cavity of the cover; then removing the mock inflator from the cushion to form a cavity within the cushion for the inflator/horn assembly.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This application discloses an apparatus and method of automatically folding a cushion (air bag) and installing an inflator/assembly within an air bag module.  
           [0002]    The major components of an air bag module include a cushion and a cover containing the horn assembly. A horn assembly comprising membrane switches is mounted to the cover and is actuated by pressing the exterior of the cover. Such a configuration requires that the cushion be folded in a specific uniform manner. This process however does not produce consistent results. As appreciated, the cushion applies a specific amount of resistance force on the horn assembly. If the cushion is not installed in a consistent uniform manner, the force that needs to be applied to activate the horn will be different from assembly to assembly. Some assemblies may require an excessive amount of force to operate the horn, while others may be activated in a spurious manner simply by the force exerted by the cushion on the horn assembly, which varies over time. For example, after the cushion is installed, there is a settling period wherein the air bag attempts to unfold into a more natural uncompressed state. Such settling may change the amount of force required to activate the horn. In the worst cases the horn may sound without any applied force on the cover. As appreciated, such circumstances create a great deal of customer dissatisfaction.  
           [0003]    One configuration that corrects the above problem is to relocate the horn assembly from being between the cover and the cushion to being between the cushion and the inflator. Such a configuration provides for a consistent amount of force applied between the inflator and the horn assembly. However, the problem of consistent cushion folding or compression and the tendency to uncompress still creates unwanted and undesirable variations in the required force that must be applied to the cover to activate the horn mechanism.  
           [0004]    For these reasons, an apparatus and method for installing an air bag into a cover that can produce a consistent cushion fold in the area where the horn is located is needed.  
         SUMMARY OF THE INVENTION  
         [0005]    The subject invention is an apparatus and method for installing a cushion (also referred to as an air bag) into a cover so that a uniform and consistent thickness of the cushion will lie between an inflator/horn assembly and an under surface of the top of the cover. In this manner, variations in the level of force applied to the under surface of the cover, and to the inflator/horn assembly, are minimized.  
           [0006]    The invention includes a folding apparatus, machine or assembly for installing the cushion to the cover. The assembly includes a base for supporting the cover, a housing or tube defining an internal cavity and an upper and a lower platform. In one embodiment, an air bag housing and a mock inflator are attached to a piston slidably disposed within the assembly&#39;s cavity and movable between the upper platform and the lower platform.  
           [0007]    The method of the invention includes the steps of attaching the air bag housing, cushion, and a retaining ring to the mock inflator (in another embodiment just to the piston), placing the cover in the folding assembly, compacting the cushion into the cover and around the mock inflator (if used), such that the cushion fills the interior of the cover, and removing the mock inflator from the cushion thereby forming a cavity or depression within the folded cushion. The actual inflator or inflator/horn assembly is then placed within the depression and secured to the air bag housing. Other folding methods are also disclosed.  
           [0008]    The subject method provides for the consistent and automatic installation of the cushion into a cover to yield a consistent cushion fold in particular at or near the top of the inflator/horn assembly. It should be appreciated that the folding method therein can be used independent of the type of horn switch, nor does the method require that a horn switch be placed within the cover. With this invention a consistent predetermined amount of cushion fabric is disposed between the underside of the cover and region of the inflator/horn assembly so that a predetermined level of force applied to the cover will activate the horn (if used). 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows:  
         [0010]    [0010]FIG. 1 is an exploded view of the folding mechanism;  
         [0011]    [0011]FIG. 2 is a perspective view of the cushion mounted to the air bag housing;  
         [0012]    [0012]FIG. 2 a  shows the cushion and air bag housing attached to a spacer or mock inflator FIG. 3 is a perspective view of the folding mechanism in the load position with the cushion in a free state;  
         [0013]    [0013]FIG. 4 is a view of the folding mechanism in the closed compacting position that shows the cushion prior to installation into the cover;  
         [0014]    [0014]FIG. 5 is a view of the folding mechanism in the compacting position;  
         [0015]    [0015]FIG. 6 is a partial cross-sectional view of the folding mechanism in the compacting position;  
         [0016]    [0016]FIG. 7 is a cross-sectional view of the cover with the cushion installed; and  
         [0017]    [0017]FIG. 8 is a cross-sectional view of the cover with the cushion and the inflator/horn assembly.  
         [0018]    [0018]FIG. 9 shows an alternative embodiment of the invention.  
         [0019]    [0019]FIG. 10 shows an alternate piston.  
         [0020]    [0020]FIG. 11 is an alternate embodiment of the invention.  
         [0021]    [0021]FIG. 12 shows an inflator installed in the embodiment of FIG. 11.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]    Referring to the FIGUREs, wherein like numerals indicate like or corresponding parts throughout the several views, the subject invention is an apparatus and method for installing a cushion  12  into a cover  14 . Upon installation of the inflator the module is virtually complete except for permanently fixing the cover and air bag housing together (if needed). The method of folding the cushion and folding apparatus can be used with many different air bag module configurations. In the preferred embodiment of the invention it is contemplated the inflator will be part of an inflator/horn assembly  36 . This construction places a pressure horn mechanism or switch upon the top, typically flat surface of the inflator. Those familiar with the construction of air bag modules, and as mentioned above, know that many modules fasten a membrane horn switch to the undersurface of the cover with the air bag resting on the membrane switch while other modules do not contain a horn switch within the module. Other modules float relative to an external horn switch. The folding apparatus and method can be used with these other types of modules as well.  
         [0023]    Referring to FIG. 1, the folding apparatus  10  includes a tubular housing or tube  16  having an internal cavity  18 . The apparatus also includes an upper and lower platform  20 ,  22  disposed on opposite ends of the tube  16 . It is preferable that at least the front side of the tube  16  is transparent. In practice the tube can be made from extruded clear plastic (one such plastic is Lexan), so all of the walls or sides of the tube are transparent. A base  24  disposed below the lower platform  22  receives and secures the cover  14  and matingly engages with the lower platform  22  of the tube  16 . The base includes a cavity  24   a  having a shape that conforms to the exterior shape of the air bag cover  14 . As can be appreciated, the cover is shown elevated relative to the cavity  24   a . The tube  16  is movable between a loading position where the lower platform  22  of the housing is pulled or otherwise moved away from the base  24  and an installing position where the lower platform  22  is engaged with the base  24 . This can be accomplished in many ways. For example, the base  24  can include a plurality of locating pins  25  that are received within mating apertures in the lower platform  22 . The tube can be supported by rails exterior to the tube. As a further alternate, the tube and all of the structure associated with it can be physically lifted from the base to provide access to the base. Alternatively, the pins  15  can be relatively long and the tube can be slid upwardly on these pins while still remaining attached to the pins, again to provide access to the base to permit the cover to be placed upon the base.  
         [0024]    The internal cavity or inside  18  of the tube  16  is shaped to mate or conform with the perimeter of the housing  28  and guides the cushion  12  into the interior, cup-shaped cavity  26  of the cover  14  as the housing is lowered. The air bag housing  28  is slidable within the interior  18  of the tube  16  and is movable between the upper and lower platforms  20 ,  22 . The air bag housing also includes a central opening  30 . As shown in the illustrated embodiment, the air bag housing is generally square-shaped but other exterior profiles can be used. As also shown in FIG. 1, the cushion  12  includes an opening  13  in a neck portion  12   a  thereof. The neck portion also includes a plurality of small openings  15 . The folding apparatus  10  further includes a piston  32  that is movable through the upper platform and through the interior or interior cavity of the tube. Preferably, the piston  32  is actuated pneumatically but the piston can be manually moved or activated by mechanical, electrical or other means. This is also true for the tube. A mock or substitute inflator  34 , also shown in FIGS. 1 and 6, is attached to the lower end of the piston  32  and is sized to fit into the opening  30  of the air bag housing  28 .  
         [0025]    It is preferable that the mock inflator  34  is of the same outer shape as the inflator or of the inflator/horn assembly  36  that will be used in the air bag module. As will become apparent from the discussion below, during the folding process, the mock inflator  34  forms a consistent and uniform depression for the later installation of the inflator or inflator/horn assembly  36 .  
         [0026]    The method of installing or folding the cushion  12  into the cover  14  is as follows. Prior to operating the folding apparatus, a subassembly  31  comprising the air bag housing, retaining ring and cushion is created. The retaining ring is placed within the neck of the cushion with its studs  40  extending through the openings  15  of the cushion. Thereafter the studs  40  are placed through the complementary openings  29  in the air bag housing  28 . In this configuration, shown in FIG. 2, the cushion  12  hangs freely from the air bag housing  28 .  
         [0027]    The subassembly  31  is installed in the folding apparatus by raising or lifting the lower platform  22  (tube  10 , etc.) off the base  24  to a height that is convenient for the operator to install the subassembly  31  and also to install the cover into the base. With the tube in an elevated position, the piston  32  is lowered exposing the spacer or mock inflator  34 . The subassembly including the housing, retainer and cushion is positioned within the folding apparatus by inserting the retainer studs  40  into the corresponding openings  41  in the flange  43  of the mock inflator  34 . This configuration is shown in FIG. 2. As can be appreciated, in the mounted configuration of FIG. 2 a , the air bag housing will become aligned with the interior of tube  16  as the flange  41   a  of the mock inflator, which is attached to the piston (not shown) is aligned to the interior wall of the tube. The subassembly  31  is movable with the piston and mock inflator. Consequently, a means is provided to temporarily connect the subassembly to the mock assembly or piston. The mock inflator or piston can include a permanent magnet, which attracts the metal studs or typically the metal retaining ring or the metal housing. Instead of a magnet, an electromagnet can be installed with the mock assembly or piston. The magnet or electromagnet is diagrammatically shown by numeral  45 . A mechanical fastener, such as a nut, can also be used to secure each threaded fastener  40  to the flange of the mock inflator. A number of other mechanical fasteners can be employed.  
         [0028]    Referring to FIG. 3, installation continues by placing the cover  14  into the cavity  24   a  of the base  24 . As can be appreciated, the cover can be placed within the base prior to attaching the subassembly to the mock inflator.  
         [0029]    Referring to FIG. 4, installation continues by raising the piston  32  within the tube  16  toward the upper platform  20  to prevent any portion of the cushion  12  from becoming trapped between the lower platform  22  and the base  24 . As the piston is raised, the friction between the tube  16  and the cushion will align the cushion to the sides of the tube.  
         [0030]    The tube  16  is then lowered to a closed position to engage the base  24 . The lower platform  22  closes against the base  24  and around the cover  14 . In this position the tube  16  abuts the base  24  and the piston  32  is fully or partially retracted such that the cushion  12  hangs free from the air bag housing  28  within the cavity  18 . The interior of the tube  18  guides the cushion  12  into the interior (cavity)  26  of the cover  14  as the piston  32  is lowered. As can be appreciated, the shape of the tube will determine the final outside shape of the cushion, meaning the folded cushion can be made to fit any geometry of the cover, or to a shape that is completely independent of the shape of the cavity  26  of the cover  14 .  
         [0031]    The piston  32  is now lowered pushing the cushion  12  into the cavity  26  or interior of the upturned cover. FIG. 5 shows the piston  32  fully lowered and in the orientation in which the cushion is compacted or folded within the cover  14 . As the air bag housing is lowered onto the cover, the cushion is pressed into the interior or cover cavity. The mock inflator prevents the cushion from being placed in the center of the cover as also shown in FIG. 6. FIG. 6 additionally shows a mechanism fastener, such as nut  50 , which secures each retainer stud to the flange of the mock inflator. The mock inflator  34  forms an impression or depression  42  in the air bag cushion  12  into which the actual inflator or inflator/horn assembly  36  will be placed. If the mock inflator (or piston) includes an electromagnet such as  45 , after the magnetic field is removed, both the tube  16  and the piston  32  are raised and the module is then removed from the base. If the design of the folding apparatus does not include a mechanism to hold and release the air bag housing, which can be automatically disconnected from the housing, the sequence of raising the piston and tube will vary. For example, with a mechanical fastener, the tube  16  is first retracted, leaving the piston in its lowered position, the housing is disconnected from the mechanical fastener and the piston withdrawn. If a permanent magnet is used, the tube  16  can be retracted initially leaving the piston in place. Thereafter the operator can grasp the module, holding it in place as the piston is withdrawn, thereby disconnecting the magnetized mock inflator from the air bag housing.  
         [0032]    [0032]FIG. 7 shows the cover, housing and cushion in isolation; the mock inflator has been removed. The depression  42  formed by the mock inflator  34  can be clearly seen. A uniform thickness of cushion material will reside adjacent the undersurface of the cover  12 , therefore a determinable amount of pressure will be needed to activate the horn switch (not shown in FIG. 7). Each air bag cushion  12  will be compacted into the interior  26  of its cover essentially the same way every time without intricate and time-consuming folding techniques. The cover  12  is then secured to the housing  28  in a known manner. For example, rivets can be used to fasten the housing and cover, if needed.  
         [0033]    [0033]FIG. 8 shows a completed air bag module with the assembly  36  (with an inflator  35  and optional horn switch  37 ) installed into the depression  42  of the air bag cushion  12 . The inflator assembly is secured to the housing with fasteners such as nuts  50  or rivets or other means.  
         [0034]    Reference is briefly made to FIGS. 9 and 10. In this embodiment the lower portion of the piston includes only the flange  41   a  with its openings. The mock inflator is not used. In this embodiment, the subassembly  31  also includes the actual inflator  35  and/or assembly  36 . The inflator flange  41  is placed on the retainer studs and inserted within the housing opening  30  into the cushion. Thereafter this subassembly  31  is fitted to the piston flange and is movable therewith. The inflator is received within the opening  41   b  in the flange  41   a  (see FIG. 10). The extending rear of the inflator is positioned in the piston  32 . As can be appreciated, the method of folding the cushion is the same as described above. As can be appreciated, the actual inflator is now automatically installed within the housing and in concert with the automatically folded cushion.  
         [0035]    Reference is now made to FIG. 11, which shows a further embodiment of the invention, which uses neither the mock inflator nor the actual inflator in the process of inserting the cushion and folding the cushion in the cover. In this embodiment, the piston  32  is further modified in that the flange  41   a , shown in FIG. 10, completely encloses the end of the piston; that is, opening  42   d  is removed or closed. In this embodiment, the retainer and cushion and housing are secured to each other as mentioned above and this subassembly is then secured to the flange  41   a  of piston  32 . This subassembly may be secured to the piston by mechanical or electromechanical means. As before, the piston  32  is raised, thereby extending the air bag  18  within the interior walls of the tube. Thereafter, the piston is moved downwardly, placing the air bag  18  and the housing  28  within the cover. Subsequently, the housing is disconnected from the piston and the cover, air bag, housing, etc. are removed from the folding apparatus. As can be seen from the cross-sectional view in FIG. 11, by not using the mock inflator (or the actual inflator) a greater volume is provided into which the cushion (air bag)  18  can be folded.  
         [0036]    Consequently, the folded configuration of the air bag shown in FIG. 11 is less dense than the air bag shown in the earlier drawings. The significance of this is that the air bag or cushion material in the vicinity of the central opening  30  of the housing is rather pliable or cushiony. Therefore, it is relatively easy to insert the forward portion of an inflator, that is that portion with exit ports  39  (such as shown in FIG. 8) through the opening  30  with very little resistance offered by the folded air bag. As before, this inflator would include a flange  41  to receive the studs  40  of the retaining ring  38  and will be secured by fasteners such as  50  in a manner as discussed above.  
         [0037]    The foregoing description is exemplary and not just a material specification. The invention has been described in an illustrative manner, and should be understood that the terminology used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications are within the scope of this invention. It is understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.