Abstract:
A modular helmet system having a helmet base to protect from impacts the crown of a wearer&#39;s head and terminating basally in a rear rim and side rims; a C-shaped extension detachably connected to said rims to protect from impacts, when fitted to the helmet base, the base of a wearer&#39;s skull; and a crown comb detachably connected centrally over the crown of the helmet base. The helmet base is provided with ventilation windows centrally located over its crown. The comb covers and seals said ventilation windows. The comb is also employed to secure the extension in place, when fitted on the helmet base.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a continuation of PCT International Application No. PCT/GB03/01411, filed Apr. 1, 2003 (now abandoned). 

   BACKGROUND 
   The present invention relates to helmets, and in particular to helmets adaptable to different situations. 
   In the rescue services there are various levels of protection needed depending on the situation personnel are likely to find themselves. 
   Thus firefighters need maximum protection against impacts to the head coming from both above and to the sides and from behind the head. They also need effective all-round flame and heat protection. 
   On the other hand, paramedics need less protection, on the whole, when entering a fire or accident situation to treat a victim. It is not likely that they will expose themselves to the same risks as firefighters because it is not their role to bring fires under control. They are not interfering with building structures, at least not to the same extent as firefighters. Moreover, they need all their senses, including hearing to treat patients effectively. 
   Finally, in mountain rescue, the helmet is primarily to protect against falls (rather than against falling object impacts) and the operator is often exerting more physical effort. Thus different levels of protection, and ventilation, are again required. 
   U.S. Pat. No. 4,975,980 discloses a firefighter helmet having an integral adjustable fire-resistant ear flap and hood. U.S. Pat. No. 6,032,297 discloses a helmet constructed from a number of components. GB-A-2361408 discloses a motorcycle helmet constructed from component parts that clip together. DE-A-3214020 and GB-A-2175490 both show a modular crash helmet comprising a base helmet and various components that can be added to configure the helmet in different ways, for example by the addition of a ring element to convert the helmet from open-face to full-face protection. 
   Presently commercially available helmets permit attachment of various items such as head lamps, cameras, visors etc. 
   SUMMARY 
   It is an object of the present invention therefore to provide a helmet capable of meeting the demands of different applications. 
   In accordance with the present invention there is provided a modular helmet system comprising:
         i) a helmet base to protect from impacts to the crown of a wearer&#39;s head and terminating basally in a rear rim and side rims;   ii) a C-shaped extension detachably connected to the rims to protect from impacts, when fitted to the helmet base, to the side and rear of a wearer&#39;s skull; and   iii) a crown comb detachably connectable centrally over the crown of the helmet base and arranged, when the extension is employed, to secure the extension in place on the helmet base.       

   Preferably said helmet base is provided with ventilation windows. The windows may be centrally located over the crown of the helmet base. 
   The comb may cover and seal said ventilation windows. Preferably, the comb is detachably connectable to the helmet base independently of the extension. 
   Preferably, the extension has two arms and a body, at the end of each arm there being provided an upstanding catch element, and the side rims have a slot to receive the catch elements when the base and extension are moved towards one another in an engagement direction. 
   Preferably, the catch elements engage catch lugs in the slots by movement transverse to the engagement direction after moving the catch elements into the slots. 
   Preferably, the comb has a sleeve at its base to receive a pin, and the helmet base has a pair of open-sided cups facing one another at the back of the helmet base, the open sides opening towards the front of the helmet base, whereby the comb is connected to the helmet base by inserting said pin in said sleeve, engaging the ends of the pin in the cups, and rotating the comb so as to lever it over the crown of the helmet base. 
   Preferably, the comb has a latch on its front end remote from said sleeve and adapted to engage a corresponding element on the front of the helmet base. The latch may comprise a pair of transversely and outwardly facing barbs on the end of resilient prongs. The corresponding element in this event may comprise a slot opening in the front wall of the helmet base, into which opening the prongs can enter, the barbs snapping into engagement with the ends of the slot opening. The prongs are preferably engageable to release the comb from the helmet base from under and inside the front of the helmet base. 
   The extension preferably has a pair of coaxial rings on its body, having an inner separation between them of an amount slightly greater than the length of the sleeve. The cups are separated from one another by an amount slightly greater than the outer separation of the rings; whereby the extension is connectable to said helmet base by (i) engaging the comb with the extension by sliding the pin through the rings and sleeve when the rings are aligned with and surround the sleeve; (ii) engaging the catch elements in the slots by movement of the extension towards the helmet base in the engagement direction and until the extension abuts the rims and the catch elements are aligned with the catch lugs; and (iii) simultaneously engaging the ends of the pin in the mouths of the cups by movement of the extension in the direction transverse the engagement direction and by pivoting the comb around the pins to lever it over the crown of the helmet base, pull the pin into full engagement with the cups, and also pull the catch elements into engagement with the catch lugs, and whereby the pin is prevented from disengaging the cups, the sleeve and rings. 
   Engagement of the crown comb over the helmet base prevents the extension moving opposite the transverse direction to release the elements and lugs. 
   The catch elements may comprise hooks and the lug studs. The opening of the hooks may be rearwardly directed with respect to the helmet base. 
   The studs may be axles of accessory attachment brackets provided on the sides of the base helmet, which axles pass through apertures formed in the sides of said slots. 
   Thus, with the helmet base alone, protection against impacts from above are provided while ventilation can be had to the top and sides of the wearer&#39;s head and up and through the helmet via the ventilation slots. 
   When the crown comb alone is added, a further layer of impact protection, over the most likely area for impacts from falling objects, is provided. Thus, the helmet in this form has application for paramedics, where side impacts are not so likely, good protection from falling objects is desirable, but where ventilation is not such a pressing requirement. 
   Moreover, the central crown line of the helmet is that part most likely to become scuffed, in time. Consequently the facility to exchange crown combs permits the aesthetic appearance of the helmet to be maintained. Indeed, the crown comb provides a convenient location for identification indicia or decals. 
   Finally, when the extension and crown comb are employed maximum protection from impact is provided, while at the same time routes for the passage of flame or hot gases through the helmet are minimized. 
   Indeed, the primary use of the system according to the invention is not so much that different users will always use the system in just one of its forms, but rather that any user can adapt the system to suit different situations. It may be that firefighters might typically use the system in its most protective form, but equally they may from time to time meet situations where less protection is needed and ventilation is wanted. Likewise, paramedics and the like might typically use the system in its lightest form, but may occasionally enter situations where a greater level of protection is needed. 
   Indeed, the invention separately provides a crown comb and an extension for the helmet system of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which: 
       FIGS. 1   a – 1   d  show, respectively, a front view, rear view, plan view and side view of a helmet fully assembled in accordance with the present invention; 
       FIGS. 2   a – 2   d  show, respectively, a front view, rear view, plan view and side view of a helmet base in accordance with the present invention and forming part of the helmet of  FIG. 1 ; 
       FIG. 3  is a detail of the area designated III in  FIG. 1   d;    
       FIGS. 4   a – 4   c  show, respectively, a rear view, plan view and side view of an extension forming part of the helmet of  FIG. 1 ; 
       FIGS. 5   a – 5   d  show, respectively, a front view, rear view, plan view and side view of a crown comb forming part of the helmet of  FIG. 1 ; and 
       FIG. 6  is an exploded perspective view of a preferred form of helmet in accordance with the invention. 
   

   DETAILED DESCRIPTION 
   In the drawings, a helmet  10  is constructed from a helmet system in accordance with the present invention comprising three primary units. The first unit is a base helmet, generally designated  120 , shown alone in  FIGS. 2   a – 2   d . The second unit is C-shaped extension, generally designated  140 , shown alone in  FIGS. 4   a – 4   d , and the third unit is a crown comb, generally designated  160 , shown alone in  FIGS. 5   a – 5   d . Each unit is injection molded from plastics material. 
   Referring first to the helmet base  120  in  FIGS. 2   a – 2   d , this comprises a domed shell  14  designed to fit on a user&#39;s head and provide protection against impacts towards the top of the wearer&#39;s skull. A series of ventilation windows  16   a ,  16   b  are provided over a central trench  18  over the top of the shell  14 . One ventilation window  16   a  faces towards the front, and is relatively large, while four rearwardly facing ventilation windows  16   b  are provided towards the rear of the helmet shell  14 . The front of the helmet base  120  has a peak  17  and side rims  20  merging into a rear rim  22 . Rims  20  and  22  are coplanar. In the center of rim  22  is a hinge seat  24  defined between two C-shaped cups  26 , one at either end of the seat  24 . The cups  26  open towards the front, and have bottoms  25  facing one another. 
   Notches  23  are disposed on the inside of the rims  20  extending into the rims  22 . A slot-opening  27  is formed in the bottom of trench  18  and penetrates the peak  17  of the shell  14 . 
   Turning to  FIGS. 4   a – 4   c , the extension  140  is C-shaped and comprises side arms  30  merging into body  32 . The extension  140  likewise has a coplanar rim in the form of side rims  34  and merging into rear rim  36 . Upstanding from the end of each arm  30 , from the side rim  34 , are two catch elements  38 , comprising hooks  39  that are rearwardly opening. The rims  34  are provided with tongues  40  that extend into the rear rims  36 . The tongues  40  correspond in size, shape and orientation with the notches  23  on the rims  20 , 22  in the helmet base  120  (see  FIG. 2   a ). 
   Across the rear rim  36  are disposed two spaced, closed rings  42  integrally formed with the rest of the extension  140 . The rings  42  have open bores  44 . 
   Turning to  FIGS. 5   a – 5   d , the crown comb  160  comprises a curved channel section  60  having downwardly depending lips  61 . At a rear end of the comb  160  is formed a sleeve  62  having a bore  64  of the same diameter as both the bore  44  of the rings  42  on the extension  140  (see  FIG. 4   c ), and the cups  26  of the helmet base  120  (see  FIGS. 2   a ,  2   b ,  2   d ). A hole  66  is formed in the side of the sleeve  62 . This is to permit a ball (not shown) spring-loaded in a pin (not shown, but visible at  126  in  FIG. 1   a ) to snap into the hole  66  and locate the pin in the sleeve  62  when the pin is inserted therein. The pin is of such a length that it extends beyond the ends of the sleeve  62 . It is, in fact, the same length as the distance between the facing bottoms  25  of the cups  26  of the helmet base  120  (see  FIG. 2   a ). 
   On the end of front  68  of the crown comb  160  is formed a latch  70 . The latch  70  comprises two transversely and outwardly facing barbs  72  and a central support  74  adapted to support the barbs  72  and prevent excessive deflection thereof, as explained further below. 
   The helmet base illustrated in  FIG. 2  has application in its own right, without further adaptation as explained below. The helmet is light, it provides a minimum level of head protection, and it has ventilation slots to permit a cooling airflow to the head of the user. Nevertheless, its primary application is as part of the overall system explained below. In this respect firefighters taking part in a rope rescue might employ the helmet in this configuration. 
   The helmet is not shown with the normal accoutrements of a helmet, such as the internal lining or the straps to retain the helmet in position, or an integral visor. These accoutrements are within the ambit of the person skilled in the art and form no part of the present invention. 
   The paramedic services generally require a greater level of protection, particularly from falling objects. On the other hand, they do not, on the whole, require side impact protection. Instead, they have a need to be able to communicate effectively with victims of an accident or fire to which they have been called. Moreover, paramedic personnel are not, on the whole, exerting themselves excessively, and therefore do not require helmet ventilation. Accordingly, in a first adaptation of the base helmet, the crown comb  160  can be connected to the base helmet  120 . This is achieved by inserting the pin  126  into the sleeve  62  and then, from underneath the helmet base, clipping the ends of the pin extending from the sleeve  62  into the cups  26 . The crown comb  160  is then pivoted over the top of the helmet base shell  14  until the latch  70  snaps into the slot-opening  27  in the bottom of trench  18  of the shell  14 . 
   In this position, the lips  61  of the crown comb  160  abut sides  19  of the trench  18 . In so doing, the ventilation windows  16  are sealed. Furthermore, the crown comb itself provides further impact resistance at this most vulnerable part of the helmet. Finally, the crown comb  160  also protects the helmet from everyday scuffs and scratches, so that replacement thereof from time to time has the effect of renovating the helmet. 
   The front surface  68  of the crown comb  160  is also an ideal location for indicia or decals to be applied, so that helmets can be personalized, and simply by connecting the appropriate crown comb  160 . 
   Equally, however, firefighters might use the helmet in this configuration when full protection from side impacts and from flame and heat is not required. 
   Finally, firefighters in many situations require maximum protection, not only from objects falling vertically and impacting the crown of the helmet, but also frequently from the side. When building structures and the like collapse, they frequently throw objects with a horizontal trajectory. Firefighters also require heat and flame protection to the back and sides of the skull and neck region above the collar of their overcoat protection. Accordingly, the present invention provides the extension  140 . 
   To connect this to the helmet base  120 , the crown comb  160  is first connected to the extension  140 . This is achieved by sliding the pin  126  through the bores  44  of the rings  42  while the sleeve  62  of the crown comb  160  is disposed between them. Again, once the ball in the pin snaps into engagement with the hole  66  in the sleeve  62 , the crown comb  160  is securely connected to the extension  140 . 
   The next stage is for the catch elements  38  to be inserted in a slot or pocket  29  (see  FIG. 3 ) formed in the side of the shell  14  and opening downwardly in the front of the rim  20 . Across the slot  29  there spans a catch lug  31  in the form of an axle for a bracket (not shown). The bracket would be provided for various accessories, useful to the rescue services, to be connected to the helmet. Such accessories include lamps and cameras, although that is not an exhaustive list. 
   In order to pass the hook  39  of the catch element  38  over the axle  31 , the slot  29  is wider than the width of the catch element  38 . Thus, the catch element is first inserted in an engagement direction that is essentially perpendicular to the plane of the rims  20 , 34 . Then, the extension  140  is moved transversely to that engagement direction (that is to say, rearwardly with respect to the helmet base  120 ). At the same time, the ends of the pin  126  extending from the rings  42  are snapped into the mouths of the cups  26 . Also at this time, the tongues  40  snap into engagement with the corresponding grooves in the side and rear rims  20 ,  22  of the helmet base shell  14 . Thus three connections are effected substantially simultaneously: the hook  39  engages the axle  31 ; the tongues  40  engage the grooves in the helmet rims  20 , 22 ; and the pin  126  snaps into the cups  26 . 
   To complete the connection and prevent corresponding disconnection of the extension from the helmet base  120 , the crown comb  160  is pivoted over the top of the helmet, in the same way as described above, until the latch  72  engages the slot  27 . This prevents the pin  127  from moving forward to disengage from cups  26 . Indeed, in  FIG. 1   a , the pin  126  is illustrated in engagement with the cups  26 , rings  42  and sleeves  62 . 
   Also visible in  FIG. 1   a  are the tips of the barbs  72 . It is a feature of the present invention that these can be released from the slot opening  28  from inside the front of the helmet using a gloved hand by pressing them together. Because a wearer&#39;s touch sensitivity is limited through gloves, the support  74  prevents the wearer from deflecting the barbs, when they are pinched together, by an amount that will cause yielding of the plastics material. 
   Turning to  FIG. 6 , this shows a preferred form of helmet which has the following modifications with respect to that described above. 
   In the first place, a modified latch  70 ′ is provided for the comb  160 ′. Here, the latch is a simple barbed tab  72 ′ adapted to hook under the lip of slot-opening  27  in the base helmet  120 ′. Secondly, pin  126 ′ is here a hollow tube provided with an integral tongue hinged in its side having a lateral projection  131  that snaps into engagement with aperture  66 ′ when the pin is slid into the sleeve  62 ′ of the comb  160 ′. 
   In  FIG. 6 , helmet  120 ′ is shown with an integral visor  200  which is pivoted in the helmet by any convenient means within the ambit of a person skilled in the art. Therefore, the visor is not described further, save to say that, in this case, it is provided with three arcuate rails (not visible in the drawings), two on either side and one in the middle at its top. The helmet base is likewise provided with three correspondingly positioned tracks (also not shown) through which the rails can slide to move the visor between the operative position shown in  FIG. 6  and a stowed position inside the helmet base  120 ′. Space is provided for this purpose between the shell of the helmet base and the seating for the users head retained inside the helmet. 
   A lamp  202  is shown received in a lamp bracket  204  connectable to the side of the helmet by being screwed into a thread formed in axle  31 . Axle  31  is not visible in  FIG. 6  because a cover-blank  206  hides connection port  208 , and the axle  31 , for the bracket  204  when it is not employed. 
   Finally, extension  140 ′ differs little from that described above except that catch elements  38 ′ are here separate components from the extension and constructed from different material to provide extra strength and rigidity. They are pressed/snapped into slots  210  formed in the rim faces  34  and are provided with barbs to prevent their subsequent removal. 
   Although the extension provides protection from a number of attacks, including heat and flame, nevertheless, ventilation slots  212  are provided through which cooling air may be drawn. 
   While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention.