BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a system for sewing a multi-piece air bag.

Many air bags, used in vehicle supplemental safety restrint systems, comprise a number of panels of material which are often manually sewn together. The present invention presents a device which will enable the automation of the sewing process .

Accordingly the invention comprises: a device for holding a plurality of pieces of fabric in a preferred orientation to enable adjacent pieces to be sewn together along pre-determined sew lines comprising: a plate including a plurality of slits, the positions of each slit corresponding to the location of the desired sew lines and an outer frame 64 secured about the periphery of the plate. The fabric to be sewn is laid upon the plate with edges of adjacent pieces overlaying each other and above a corresponding slit . The device further includes locating means for locating certain pieces of fabric on the plate in a predetermined orientation and at least one positioning frame movably secured relative to the outer frame or plate. Each positioning frame including specified sets of bars closely spaced one to the other and positioned such that when each positioning frame is lowered upon the plate the spacing between designated set of bars is above a corresponding slit and above the location of the overlaid fabric pieces. A needle of a sewing head is moved between the spacing of the bars to sew various pieces of fabric together.

Many other objects and purposes of the invention will be clear from the following detailed description of the drawings .

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings :

FIGURE 1 diagrammatically illustrates a cross- sectional view of a multi-piece air bag.

FIGURE 2 illustrates a cross-sectional view of the air bag shown in FIGURE 1 mounted to a cylindrical retainer.

FIGURE 3 illustrates a sewing platform used in the present invention.

FIGURE 4 is a plan view of a plurality of pieces of fabric which are used to form an air bag.

FIGURE 5 diagrammatically illustrates a cross sectional view showing the relative position of a plurality of fabric pieces upon the platform.

FIGURE 6 shows a more detailed view of a sewing platform.

FIGURE 7-10 show top plan views of positioning frames . FIGURE 11 illustrate cross-sectional view of part of a positioning frame.

FIGURES 12 & 13 illustrates a cross-sectional view showing a locking mechanism.

FIGURE 14 shows a sewing head. FIGURE 15 shows a strke plate.

DETAILED DESCRIPTION OF THE DRAWINS

FIGURES 1 and 2 show a prior art air bag and housing. While these FIGURES generally do not pertain to the present invention they are helpful in identifying the general structure of an air bag. FIGURE 1 diagrammatically illustrates a multi-piece air bag 30 comprising a main panel 32 sewn to a first neck panel 34 and to a second neck panel 36. Positioned inside the air bag is a continuous loop piece of fabric 38 the ends 39a,b of which are sewn to the main panel 32. Those skilled in the art will recognize that the panel 38 provides tethers 40a and 40b which restrict the expansion of and also controls the trajectory the air bag 30 will take upon inflation. Each of the neck panels 34 and 36 include a plurality openings 42 and 44. Similarly the panel 38 at its middle 46 includes a like plurality of openings 48. As can be appreciated the sides of the various panels are sewn together giving the air bag its sack-like appearance.

FIGURE 2 illustrates the air bag shown in FIGURE 1 mounted to a cylindrical retainer or housing 50. Retainers are typically used in air bag systems especially on the passenger side of the vehicle and support a gas generator (not shown), of known variety. The exemplary retainer 50 includes a plurality of fasteners 52 to typically four, extending therefrom. As can be seen from FIGURE 2 , the retainer 50 is positioned in the middle 46 of the panel 38 with each fastener 52 inserted into a corresponding one of the openings 48. The neck flaps 42 and 44 are secured about the fasteners 52 in overlapping relationship with a fastener 52 extending through each of the openings 42 and 44. The

air bag 30 is subsequently folded (not shown) into a compact package about the retainer.

Reference is made to FIGURE 3 which illustrates a sewing platform 60 comprising a plate 62 and a frame 64 secured about the periphery of the plate 62. The plate includes a plurality of slots or slits such as 66a-66i, the purpose of which will be clear from the description below. Positioned near slot 66a are a plurality of fingers or pins 70a-70d extending upwardly f om plate 62. Similarly, positioned proximate slit 66i is another plurality of fingers or pins 72a-72d. The number of pins 70a-d and 72a-d correspond to the number of openings 42 and 44 in each neck piece 34 and 36. Also visible in FIGURE 3 are a plurality of hinges 74a,b and 76a-d, and 78a,b.

Reference is made to FIGURE 4 which shows a top plan view of plurality of pieces of material or fabric, used to form an air bag. In the present invention, each of the pieces of material is laid flat upon the platform 60 in a predetermined manner and orientation and then sewn together along designated sew lines or seams . As be also seen from FIGURE 4 the neck panel includes extending wings 51a,b. In FIGURE 6 these wings are folded inwardly so that they do not extend beyond the sides of the platform 60. The various pieces of fabric described in FIGURE 4 are also shown in FIGURE 6 positioned upon the plate 62. The air bag shown in FIGURE 4 also includes the two neck pieces 34 and 36 and a main panel 32. The tether panel 38 is positioned generally in the middle of the main panel 32. The ends 39a,b of panel 38 are laid flat upon the main panel 38 to facilitate sewing. The rest of panel 38 is bunched together, as can be seen from

FIGURE 5. As illustrated the air bag as shown in FIGURE 4 may include more than the four pieces of fabric diagrammatically illustrated in FIGURES 1 and 2. The air bag 30 of this FIGURE utilizes additional layers of fabric 41a,b placed upon each of the neck pieces 34 and 36 respectively. These additional pieces 41a,b provide additional strength and also function as a heat shield. The rows of lines 47a-h show the location of each sew lines or seams. The placement of the sew lines correspond to the locations of the slots 66a-66i in the plate 62.

With reference to FIGURE 6, and as mentioned above, prior to beginning sewing the main panel 32 and the panels 34, 36 are laid flat upon the plate 62 so that respective ends 43a,b of the main panel overlap with corresponding ends 49a, 49b of panels 34,36. In order to obtain the correct lateral placement of panels 32, 34 and 36 relative to the plate 62, The plate 62 (see FIGURES 3 and 6) further includes a plurality of locating bars or blocks 130 which are useful in defining the proper placement of the panels. As can be seen a side edge 45 of the main panel 32 is positioned adjacent the blocks. Similarly side edges of the other panels are laid next to other blocks 130. The blocks can be positioned straight or skewed following the contour of the panels. The correct positioning of the neck panel 34 is insured by placing the neck panel 34 upon the retaining pins 70a-d. As can be seen the ends of the neck panel and main panel overlay slits 66a, c. The heat shield 41a is also positioned about the pins 70a-d and laid flat upon the neck panel 34 to overlay slits 66a,b. Panel 36 is similarly positioned about the other sets of pins 72a, d and overlays slits 66g,i. The heat shield 41b is

positioned on top of the panel 36, about pins 72a-d and overlays slits 66h and 66i. The plate 62, as shown in FIGURES 3 and 6 may also include a plurality of pins such as 132a,b which also serve to insure the proper lateral position the various panels.

Reference is again made to FIGURE 6. Secured to the hinges 74a,b is a first positioning platform or frame 80 which is shown in greater detail in FIGURE 7. Located near the middle of the platform 60 is a composite positioning frame 82 shown in greater detail in FIGURES

8 and 9. The composite frame is attached to hinges 76a, d and 76b, c. Positioned on the left side of the platform 60 is a third positioning frame 84 attached to hinges 78a,b. The various platforms 80,82 and 84 provide a means to clamp the panels to the plate 62 prior to and during sewing. As can be appreciated after the panels have been placed on the plate 64 the various positioning platforms 80,82 and 84 are moved downwardly and latched or locked in place. With reference to FIGURE 7 the positioning frame 80 comprises four outer frame members

90a-d. Members 90a and 90b are secured to and movable with hinges 74a and b respectively. Positioned upon frame members 90a, 90d, which are U-shaped in cross- section, are four sets of bars 98a, and 98b, 100a, and 100b, 102a, and 102b, 104a and 104b. Each set of bars 98-104 is slidable within the frame pieces 90c, 90d and positioned at a determinable location. The bars 98-104 can be fixed in place to the frame members 90c and 90d using fasteners such as pins or screws. Reference is briefly made to FIGURE 3, as can be seen four of the slits 66a-d are positioned of the left hand side of the plate 62. The respective sets of bars 98-104 are positioned within frame pieces 90c and 90d so they the bars will reside on each side of a respective one of the

slits 66a-d. As can be seen the bars of each set are generally spaced from each other defining a channel or space 51. Each channel is positioned over the overlaid panels at the location of the corresponding sew line 47. Each sew line 47 is above a corresponding silt 66. As will be seen below, the bars 98-104 are used to clamp various panels to the plate 62 at a respective sewn line location facilitating the sewing of the various pieces together.

Reference is now made to FIGURES 8 and 9 which illustrate the components of the composite positioning frame 82. The frame 82 includes an outer frame 82 ' . The frame 82 ' comprises four support members llOa-d. Members 110a and 110b are attached to hinges 76a and 76d as shown in FIGURE 3 and rotatable therewith. Frame 82 ' also supports at least one set of bars 112a,b slidable in members 110c and llOd. The bars 112 a,b are positioned and then fixed generally at the left of larger slit 66e shown in FIGURE 3. Typically, one narrow slit is positioned below each sew line. However, in the case of slit 66e it with spans two closely spaced sew lines. FIGURE 9 illustrates the second component of frame 82, that is, an inner positioning frame 82". Frame 82" is constructed of a plurality of frame members or pieces 114a-d. Frame pieces or member 114a,b are secured to hinges 76b and 76c (see FIGURE 3) . Positioning frame 82" also utilizes supports 116a, 116b and 116c ^' secured between members 114a,b and d. Positioned within and spanning the frame members 114c, d are sets closely spaced bars 118a,b and 119a,b. The set of bars 118a,b is positioned on the right hand side of the larger slit 66e while the set of bars 119a,b is positioned about the narrow slit 66f (see FIGURE 3) . FIGURE 10 shows an

isolated view of positioning frame 84 with frame members 122a-d and sets of bars 124a,b 126a,b and 128a,b. The bars will be positioned about slits 66g, 66h and 66i.

As mentioned above the platforms 80,82 and 84 are lowered are latched or locked in place. FIGURE 11 shows portions of the frame 64 and plate 62, one of the hinges such as 74a and one of the members of one of the positioning frames such as 90a. Also shown is a portion of the member 90c which includes a strke plate 141 (see FIGURE 15) with a notch or opening 140 positioned opposite a corresponding locking mechanism 142. The other frame member include similar openings and mechanisms. Various locking mechanisms 142 (two per positioning frame) are fitted into the front portion 144 of the frame 64. Each locking mechanism 142 is substantially identical to a latch used on a conventional door comprising a spring loaded triangular tongue 146 is moved inwardly when engaged by a strke plate. When each frame is lowered the tongue 150 will rest before the strke plate in opening 140 preventing it from raising. As with a convention door each tongue is retractable as a handle is rotated. Rather than using individual handles for each locking mechanism, the present invention uses a single handle 150 and bar 152. When the handle 150 is turned, the bar 152 slides in blocks 154 frame 64. Rotatable links 156 join the bar to each tongue 146. As the bar slides the links 154 rotate simultaneously withdrawing each of the tongues 146 thereby releasing each positioning platform.

Each of the positioning frames 80, 82 and 84 are biased upwardly by a pair of lifting devices such as 120a,b attached to the positioning frames by brackets

121a-f . The other end of each lifting device is attached to the frame 62. A single lifting device 120g is used to lift the inner frame 82". To prevent each of the positioning frames from oscillating as they raise due to the force of its spring, each of the devices 120a,b and may include a dampener similar to a shock absorber.

Reference is made FIGURES 12 and 13 which illustrate cross-sectional views through one of the various bars 98a of positioning frame 80. Each of the other bars of each frame is of similar construction. FIGURE 12 also shows an end edge, representative of the edges of the panels 34 and 41a, which is shown in exaggerated thickness for purposes of illustration. As can be seen, each bar 98a is generally U-shaped and includes sides 150a,b and a top 150c. Positioned interior to the bar 98a are a plurality of clamping members 152a-n. In the preferred embodiment of the invention these clamping members 152 are fabricated of metal pieces or blocks and may be of the same or varying length. Each clamping member 152a-n is resiliently coupled to the top 150c of its associated bar by two springs 154a and 150b. As can be seen, the blocks 152 bias the panels on to the plate 62. By utilizing the dual springs 154a,b and each block or clamping member 152a-n will achieve a flat or angled orientation depending upon the number of layers of fabric extending thereunder. This feature is especially desirable in transition regions of differing material thicknesses such as between the plate and a panel or between a thin panel portion and a thicker panel portion.

Having described the sewing platform 60 and how the various panels are positioned thereon the panels are now sewed together. Reference is now made to FIGURE 14 which

diagrammatically illustrates a quilting machine or a multi-axis sewing machine 160. Many such machines comprise a sewing head 162 and a table 164. As it is known in the art, these types of machines may be controlled such that the sewing head 162 or table 164 or both are movable. In the present invention the sewing platform 60 is placed upon the table 164. The table 164 or sewing head 162 are moved to position the needle 166 in the spaces 51 between a particular set of bars such as 98a,b. Thereafter the sewing head is lowered and caused to sew the various panels together which are held in place by the adjacent set of bars. The needle is progressively moved between other sets of bars to sew each sewn line or seam.

Many changes and modifications in the above described embodiment of the invention can, of course, be carried out without departing from the scope thereof. Accordingly, that scope is intended to be limited only by the scope of the appended claims.'