Patent Document

RELATED APPLICATION 
     The present application claims priority to, and the benefits of, U.S. Ser. No. 60/691,307, filed Jun. 17, 2005, the entire disclosure of which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to safety helmets, and in particular to attachment of accessories that may be optionally mounted onto the helmet. 
     BACKGROUND OF THE INVENTION 
     Helmets for head protection are worn in a variety of environments and for various purposes. Accessories may be added to the helmet according to the needs of the wearer and the demands of the use environment. Such accessories may, for example, provide additional protection, as in the case of a face shield, or additional capability such as night vision. The prior art includes two approaches to attachment of accessories: through-holes and clamps. U.S. Pat. Nos. 6,009,562, 6,009,561, 4,222,123, and 5,978,973, for example, describe attachment to the shell of a helmet by means of a through-hole and specialized grommets. While the through-holes provide secure attachment, they do not lend themselves to easy affixation and removal, are not adjustable in position, and may compromise the integrity of the helmet shell. Clamping devices are taught, for example, in U.S. Pat. Nos. 4,788,724 and 4,224,694. While these designs accommodate some positional adjustment and do not require through-holes in the shell, the security of the attachment is limited, and they do not provide for multiple accessories. In law-enforcement, fire-fighting, and military applications, for example, the ability to attach multiple accessories may be important. Therefore, there exists a need to facilitate convenient attachment and detachment of multiple accessories to a helmet. 
     SUMMARY OF THE INVENTION 
     The present invention provides a platform herein referred to as a “mounting rail” that accepts one or multiple optional accessories to a safety helmet at desired locations and with positional security. The mounting rail may have slides, threaded holes, or other mounting fixtures suited to securing the accessories. The mounting rail of the present invention may be configured to present a relatively low-profile protrusion from the helmet using physical surfaces that offer low risk of snagging or being caught in external devices when accessories are not in place. The invention allows for adjustment of the position of the accessories when they are attached to the mounting rail, which desirably accepts more than one optional accessory. 
     The mounting rail of the present invention utilizes an interface structure secured to the outer shell of the helmet, providing surfaces for mounting accessories onto the mounting rail instead of directly onto the helmet. In some embodiments, the mounting rail may be secured to the helmet shell using existing through-holes in the helmet shell and the fasteners already employed in connection with helmet-retention components such as straps or headbands. The fasteners may be, for example, rivets or nuts and bolts and may be made from plastic (for light-duty applications), stainless steel, or forge-hardened steel (for helmets providing ballistic protection). 
     A preferred embodiment of the mounting rail comprises a molded component conforming to the shape of the outer shell of the helmet. In some versions, the bottom edge of the rail fixture (which itself includes one or more rails) conforms to the bottom edge of the helmet, while in other versions, the entire fixture is raised on the side of the helmet, residing, for example, over (and conforming to at least a portion of) a bulge or other protrusion or discontinuity in the helmet. The rail fixture desirably spans a sufficient circumference of the helmet shell to overlap at least two existing through-holes provided for securing retention components thereto. The mounting rail may then be secured to the helmet shell by sharing fasteners with the retention components using these through-holes. A benefit of this embodiment is that the mounting rail can be added to already-manufactured helmets by providing the appropriate mounting rail with mounting holes at the dimensions of the existing through-holes in the helmet. If necessary, modified fasteners, which may be longer than the standard fasteners, can be provided to secure both the mounting rail and the existing retention components using the existing through-holes. Avoiding the need for additional through-holes to secure the mounting rail means that the safety features of the shell are not altered. It should be stressed, however, that the use of existing through-holes is by no means necessary. Other approaches such as co-molding or thermo-bonding with the shell, bonding using adhesives, or a combination of adhesives and one or more fasteners can be used to secure the mounting rail to the helmet shell (or to fabricate it integrally therewith). 
     As used herein, the term “rail” refers to a mounting facility with parallel boundaries, and which slidably accepts a complementary engagement member. The preferred embodiment of the mounting rail includes a recessed groove open on at least one end and preferably on both ends. Accessories having an engagement member complementary to the recessed groove may be attached to the mounting rail by sliding the engagement member into the mounting-rail groove and securing it in place. The preferred cross-sectional profile for the groove is flat on the surface toward the helmet with angular side walls; this configuration is sometimes referred to as a dove-tail recessed groove. The opening width of the groove may range from 0.25 to 1.0 inch (and is preferably 0.75 inch) with walls angled inward from 30° to 60° (and preferably at 45°). The dovetail shape retains the attaching component by means of the angled walls, but the profile may be any suitably retentive shape (such as an “L” or “T” shape) having edges that slidably retain an attaching component, allowing it to reach a desired position where it is secured into place. Means for securing the position of the mounting element are well known in the art and may include, for example, a “thumbscrew” tightener or a “tab-and-slot” engagement mechanism. 
     Accordingly, in a first aspect, the invention comprises a mounting facility for a safety helmet. The mounting facility comprises a rail, securable to the helmet, for slidably receiving an accessory therein. An inner surface of the rail may have a contour conforming to the helmet, or the rail may be formed integrally with the helmet. The mounting facility desirably has sloped ends. In general, the mounting facility of the present invention will comprise a recessed retaining groove, e.g., a dovetail arrangement involving a flat inner surface and a pair of angled side walls opposed to the inner surface, or an L or T shape. The retaining groove may be substantially flat in extent, or may have a constant-radius curvature. 
     In a second aspect, the invention comprises safety helmet including a helmet shell, a mounting facility comprising at least one rail, securable to the helmet shell, for slidably receiving an accessory engagement member therein, and at least one accessory engagement member positionable within the at least one rail and securable thereto. In addition to any one or more of the features described above, the mounting facility may have a plurality of apertures aligning with existing through-holes in the helmet shell for facilitating affixation thereto. The mounting facility may further comprise at least one threaded hole for threadably accepting an accessory; means for accepting an element conforming to the rear of the helmet shell; and/or means for accepting a hinged connecting element on the front of the helmet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which: 
         FIG. 1   a  shows the left side of a helmet having an embodiment of the mounting rail of the present invention; 
         FIG. 1   b  shows the left side of a helmet having an alternate embodiment of the mounting rail of the present invention; 
         FIG. 2  is a cross-section of the mounting rail shown in  FIG. 1   b  taken along the section  2 - 2 ; 
         FIG. 3   a  is a cross-section of the mounting rail shown in  FIG. 1   b  taken along the section  3 - 3 ; 
         FIG. 3   b  is a cross-section similar to  FIG. 3   a  showing an alternative form of the mounting rail of  FIG. 1   b;    
         FIG. 4   a  shows the mounting rail of  FIG. 1   b  with two accessories positioned to be attached; 
         FIG. 4   b  shows the mounting rail of  FIG. 4   a  with the two accessories mounted in place; 
         FIG. 5  shows another embodiment of the present invention having additional means of attaching accessories to a first mounting rail; 
         FIG. 6  shows a perspective view of the mounting rail of  FIG. 5  with an accessory mounted to the front; and 
         FIG. 7  is a view from the back of the helmet of  FIG. 5  showing an additional element for containing and/or supporting accessories. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1   a , a helmet shell  51  is shown from the left side of the user&#39;s head (the right side having symmetrical features). A mounting rail  55  in accordance with the invention is included within a fixture preferably fabricated from nylon, polypropylene, or other synthetic plastic using injection molding processes, the bottom edge of which conforms to the bottom edge of the helmet shell  51 . The fixture is secured to the exterior of helmet shell  51  by means of fasteners  53  in the front and back. In another embodiment, illustrated in  FIG. 1   b , mounting rail  55  is included within a fixture having a bottom edge that conforms to a convex extension  56  of helmet shell  51 . 
     A recessed groove  57  in the mounting rail  55  slidably accepts a complementary engagement member  59  of a potential accessory, which may be secured by tightening a securing member  60  (e.g., a standard screw, as illustrated, or a thumbscrew, tab-and-slot system, or other suitable engagement mechanism). The engagement member  59  shown in  FIGS. 1   a  and  1   b  is illustrative only; in practice, it would carry a functional accessory. Virtually any accessory suitable for mounting to the helmet  51  can be designed to have an engagement member complementary to the recessed groove  57 . 
     In  FIG. 2  the mounting rail  55  is shown in cross-section, mounted on helmet shell  51 . In the illustrated embodiment, the cross-sectional profile of the recessed groove  57  is a dove-tail configuration complementary in cross-section to that of an attaching component  59 . The dovetail shape retains the attaching component  59  by means of the angled edges  61 , but allows it to slide within the recessed groove  57  to reach a desired position where it is further secured by a tightening screw  64 . The ends of the mounting rail  55  desirably slope toward the surface of the helmet shell  51 . 
     As shown in  FIG. 3   a , the mounting rail  55  provides a geometrical interface between the curving surface of the helmet shell  51  and a straight groove  57 . A straight groove  57  is beneficial because it allows attaching component  59  to be formed with simple flat surfaces while still allowing adjustment of the position of the accessory along the length of the groove  57 . 
     On the other hand, as shown in  FIG. 3   b , another embodiment of the mounting rail utilizes a non-straight recessed groove  67 . The inner surface of the mounting rail  65  has a contour that conforms to the helmet shell  51 , and the recessed groove  67  also approximates the curved surface of the helmet shell  51  but with a constant radius. The curved groove  67  has the benefit of reducing the protrusion at the ends of the mounting rail  55  shown in  FIG. 3   a . If the recessed groove  67  has a constant radius, the attaching component  59  can have a matching curved shape and still freely slide within the groove  67 . The mounting rail  65  provides an interface between differently sized helmets having different amounts of curvature and a groove  67  with a common constant radius (independent of the size and curvature of the helmet). For accessories that do not require the flat surface as shown in  FIG. 3   a , and thus the lower profile of mounting rail  65  shown in  FIG. 3   b , a curved mounting rail may be preferred. 
       FIG. 4   a  shows the mounting rail of  FIG. 1  mounted on helmet shell  51  with two accessories  75  and  80  positioned to be attached. As illustrated, accessory  75  is an earphone; a similar earphone can be mounted on the right side of the helmet in a symmetrical mounting rail (not shown). The earphone  75  is attached by a connecting member  77  to the engagement member  79 , which can itself be positioned along recessed groove  57  by sliding engagement member  79  therealong and securing it with the thumbscrew  83 . Accessory  80  is an illuminator that can be similarly attached by sliding the engagement member  89  within recessed groove  57  and securing it with thumbscrew  83 .  FIG. 4   b  shows the mounting rail of  FIG. 4   a  with the two accessories  75 ,  80  mounted in place. 
       FIG. 5  shows another embodiment of the present invention mounted to a helmet shell  51 . In this embodiment the mounting rail  55  on the left side of the helmet (shown) is extended forward by a front connecting element  94 , which joins with the mounting rail  55  on the right side of the helmet (not shown). The entire mounting rail thus encircles three-quarters of the helmet shell  51  and is secured by means of five fasteners  53 , two on each side and one in the front, which desirably penetrate the shell using the through-holes shared with retention components (not shown). This embodiment may comprise additional attaching features, it being understood that any particular version may have some, but not necessarily all of the attaching features illustrated. In addition to the recessed groove  57  already described, this embodiment has one or more threaded holes  97 , which serve as mounting points for an accessory that can be threadably mounted therein. An attachment surface  99  on the front connecting element  94  accepts accessories such as PVS-14 night vision goggles to the front of the helmet. A hole  101   a  on the left side of the front connecting element  94  can be used in conjunction with a similar hole  101   b  on the right side to provide a hinged mounting point in the front for an additional accessory (see  FIG. 6 ). Finally, a slot  103  allows a rear connecting element  107  to be attached as further described in connection with  FIG. 7 . 
       FIG. 6  shows a face-protection accessory  105  hingeably affixed to the mounting rail of the present invention using holes  101   a  and  101   b . The face-protection accessory  105  may be further supported by a bumper  107  that braces against the helmet shell  51 . Mounting holes  101   a ,  100   b  provide a secure, hinged attachment to the helmet, allowing the face-protection accessory  105  to be hinged upward and out of the way when not needed. 
     With reference to  FIGS. 5 and 7 , a rear connecting element  107  is designed to mate with slot  103   a  in mounting rail  55  on the left side and to extend around the back of the helmet shell  51  to a similar slot  103   b  on the mounting rail on the right side of the helmet. The rear connecting element  107  is desirably slightly compliant and conformal with the outer shell  51  such that when a tension is established between the two slots  103   a  and  103   b , the rear connecting element  107  comes into close contact with the shell  51 . This rear connecting element  107 , which creates a bridge under tension between left-side and right-side mounting rails, allows the rails to better resist dislodgement by horizontal or rotational forces. The tension may be established by a pair of over-the-center latches  110   a ,  110   b , which have ends adapted to fit into slots  103   a ,  103   b , respectively, and to move hingeably downward (as indicated by the arrows) so as to snap against connecting element  107 . Alternatively, tension can be provided by other suitable means known in the art such as tightening screws that pull two parts of the rear connecting element  107  together to contract its length. Accessories may be attached externally to the rear connecting element  107  using any of the attaching features as described above in connection with  FIG. 5 . Alternatively, rear connecting element  107  can provide a protected space for smaller accessories, such as electronic components, which can be stored within the space within the rear connecting element  107  or between it and the outer shell  51 . 
     Having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. The described embodiments are to be considered in all respects as only illustrative and not restrictive.

Technology Category: 1