Abstract:
A modular handguard device configured to be slidably mated to an outer surface of an existing or affixed handguard. The handguard of the present invention may be configured to mate with any handguard to provide an extension of the handguard for purposes including mitigation of detectable heat signature, operator safety and increased reconfigurability of firearms for mission specific needs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit to provisional patent application No. 62/360,924, entitled “MODULAR HANDGUARD DEVICE FOR A FIREARM”, filed Jul. 11, 2016, which is incorporated by reference in its entirety for all purposes. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention pertains in general to shielding of surfaces as associated with firearms with elevated surface temperatures with a heat mitigation and shielding device to reduce the risk of injury to an operating user. 
       BACKGROUND OF THE INVENTION 
       [0003]    Firearms are weapons designed to fire a projectile, or round, at a high rate of speed toward an intended target. A rapidly combusting or explosive charge is initiated within the firearm to generate a rapidly expanding gas, which is controlled and directed through a barrel. The rapidly expanding gas propels a projectile out of the muzzle-end of the barrel at high velocity. The combustion of the explosive charge within the firearm subjects parts of the firearm to high pressures and temperatures. 
         [0004]    A common problem with operation of a firearm surrounds elevated surface temperature of parts of the firearm. Parts which are in contact with the explosive charge used to fire a projectile from the firearm typically exhibit the highest surface temperatures. According to ASTM C1055 (Standard Guide for Heated System Surface Conditions that Produce Contact Burn Injuries), an average person may touch a 60° C. (140° F.) surface for up to 5-seconds without sustaining an irreversible burn. When considering metallic surfaces, as commonly found on a firearm, contact with a surface over 70° C. (158° F.) results in near instantaneous tissue damage. Some portions of a firearm may exhibit temperatures in excess of 426 ° C. (800° F.). 
         [0005]    Direct contact with a surface having elevated temperatures, such as by the operator or others in near proximity of the firearm, may cause injury and/or distraction to the operator. Distractions in certain scenarios, such as covert operations or dynamic threat situations, can result in life-threatening consequences or mission failure. Distractions is such scenarios may cost an operator their life, or the life of those surrounding the operator—such as members of the operator&#39;s team. 
         [0006]    Due to the nature of a firearm, each explosive charge associated with a fired round transfers heat energy into parts of the firearm. This heat energy transfer increases the surface temperature of firearm surfaces beyond safe levels. Contact with such surfaces may injure or distract any individual that contacts such a surface. Furthermore, such surfaces increase in temperature with the firing of additional rounds, and the temperature increases more rapidly as rounds fired from the firearm are fired in more rapid succession. 
       SUMMARY OF THE INVENTION 
       [0007]    Handguards are devices affixed to a firearm, typically long-arms, which serve many purposes. One purpose of a handguard is to protect an operator and those in close proximity from injury due to contacting surfaces with elevated temperature surfaces, particularly firearm barrels. Handguards also provide attachment points to mount peripheral devices such as fore-grips, flashlights, and laser sights. Handguards also shield accessories that may be heat-sensitive from excess heat. 
         [0008]    As barrel length varies according to intended purpose, so do handguards. For instance, a short barrel may be used for increased maneuverability in close-quarters battle such as within a building. A longer barrel may be used for increased accuracy and precision for more distant targets. It is common for an operator to change a barrel within the scope of a single mission. Changing barrels to a longer barrel exposes more barrel surface, which may reach elevated temperatures and injure the operator or others in near proximity. It is common for an operator to add a suppressor, such as disclosed in U.S. application Ser. No. 15/408,224, Firearm Suppression Device, to Garst, et al., incorporated in its entirety by reference. Adding a suppressor extends the effective length of a barrel and exposes surfaces, which may reach elevated temperatures and injure the operator or others in near proximity. Changing barrels to a shorter barrel may result in the handguard extending beyond the muzzle-end of the barrel. In certain scenarios, a handguard that extends beyond the muzzle end of a barrel allows an operator to grasp a firearm in close-proximity to the muzzle end of the firearm. Grasping a firearm in close-proximity to the muzzle-end may expose the operator to potential injury from direct exposure to the muzzle blast of the firearm. Furthermore, a handguard that extends beyond the muzzle end of a firearm may result in a firearm that is heavier than necessary, and longer than necessary. A firearm that is longer than necessary is typically more difficult to maneuver in situations such as those that the operator is within a building or vehicle. 
         [0009]    The present invention surrounds a device to provide a modular handguard for use with existing firearms having affixed handguards to mitigate the risk of injury surrounding contacting surfaces of elevated temperature. It will be appreciated that an affixed handguard is a handguard affixed to a firearm or firearm barrel, typically with tools, fasteners, or adapters. An exemplary affixed handguard is disclosed by U.S. Patent Application No. 2014/0130390, Modular Rifle Handguard, to Geissele (“Geissele”), incorporated by reference in its entirety. 
         [0010]    Certain embodiments of the present invention surround a modular handguard, providing an extension of affixed handguards to alleviate problems associated with elevated surface temperatures. Certain embodiments of the present invention are manufactured from material compositions with heat mitigating characteristics. Materials having heat mitigating characteristics typically have low heat transfer properties. Materials having low heat transfer properties have reduced transmittance of heat energy through the material. The use of such a material in the manufacture of a modular handguard limits the transfer of heat energy to an external surface of a modular handguard, thus mitigating the external surface temperature of a modular handguard. Such material compositions may comprise ceramic, polymeric or other materials with a low heat transfer coefficients. In certain embodiments, a modular handguard comprises a polymeric material, and it may be preferred that the polymer has a melting point above 200° C. (392° F.). 
         [0011]    Certain embodiments comprise a modular handguard having an additional heat mitigation feature such as an intermediate insulative barrier. An intermediate insulative barrier is applied as a buffer of reduced heat transfer properties between a modular handguard and portions of an affixed handguard or firearm. Intermediate insulative barriers reduce the transmittance of heat from a firearm to an outer surface of a modular handguard which an operator may contact. An intermediate insulative barrier may comprise a material having lower heat transfer properties than materials from which the firearm or affixed handguard are made. Other forms of an intermediate insulative barrier include a sealed volume comprising a pressure lower than that of the ambient environment such as a partial vacuum or full vacuum. Alternative embodiments comprise an additional heat mitigation feature comprising strategic air-pockets designed to prevent or mitigate the passage of heat. 
         [0012]    The modular handguard of the present invention may shield parts of a firearm, reducing detectable heat signature. Detectable heat signature is typically associated with infrared radiation from surfaces having elevated surface temperatures. Detectable heat signature, transmitted by surfaces with an elevated temperature such as a barrel or suppressor, is undesired in certain scenarios. It will be further appreciated that a modular handguard made from material having heat mitigating characteristics may further reduce detectable heat signature. 
         [0013]    Certain embodiments comprise a modular handguard configured to slidably interface with an affixed handguard while maintaining a similar outer surface boundary as the affixed handguard. A modular handguard as disclosed, typically mates with an outer surface of an affixed handguard. However, it will be appreciated that a modular handguard may slidably interface with an internal or outer surface of an affixed handguard. 
         [0014]    Certain embodiments comprise a modular handguard incorporating attachment features including but not limited to: a tactical rail, Picatinny Rail as defined by MIL-STD-1913 (Military Standard [MIL-STD]-1913, Dimensioning of Accessory Mounting Rail for Small Arms Weapons, Department of Defense, 3 Feb. 1995), KeyMod rails and/or M-Lok® rails. It will be appreciated that the modular handguard may utilize attachment features known to those skilled in the art surrounding the affixing of accessories to firearms. It will be further appreciated by those skilled in the art that a modular handguard may include a plurality of attachment features. 
         [0015]    Certain embodiments of the present invention comprise a modular handguard incorporating electrically powered elements, such as lights, at the distal end of the handguard. The lights may be integrated into the body of the modular handguard during the manufacturing process. It will be appreciated that optical imaging capability and other electrically powered elements may be integrated into the body of the modular handguard. Certain technologies provide power to electrically powered elements with electrical connections such as those disclosed by U.S. Pat. No. 7,627,975 to Hines (“Hines”). However, Hines is limited to providing power to peripheral devices mounted to an attachment feature of an attached handguard. Hines does not provide power to peripheral devices mounted to a slidably attached handguard, such as the modular handguard of the present invention. Furthermore, Hines does not disclose the use of integrated lighting elements in a distal end of a handguard. It will be further appreciated that electrical transmission elements, such as wires, may be integrated into the body of a modular handguard for connection to an electrical power source, such as a battery. Such electrical transmission features provide electrical transmittance through mediums known to those skilled in the art, such as pressure connectors or mechanical interlock connectors. Transmission of electrical power through the modular handguard allows for the supply of remote power for the operation of integrated or attached peripheral devices. Additionally, integrated electronics and accessories may include various energy harvesting and energy storage capabilities known to those skilled in the art. 
         [0016]    These and other advantages will be apparent from the disclosure of the inventions contained herein. The above-described embodiments, objectives, and configurations are neither complete nor exhaustive. As will be appreciated, other embodiments of the invention are possible using, alone or in combination, one or more of the features set forth above or described in detail below. Further, this Summary is neither intended nor should it be construed as being representative of the full extent and scope of the present invention. The present invention is set forth in various levels of detail in this Summary, as well as in the attached drawings and the detailed description below, and no limitation as to the scope of the present invention is intended to either the inclusion or non-inclusion of elements, components, etc. in this Summary. Additional aspects of the present invention will become more readily apparent from the detailed description, particularly when taken together with the drawings, and the claims provided herein. 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0017]      FIG. 1 —A perspective view of certain embodiments of a modular handguard 
           [0018]      FIG. 2A —A cross-sectional view of certain embodiments of a modular handguard 
           [0019]      FIG. 2B —A cross-sectional view of certain embodiments of an affixed handguard 
           [0020]      FIG. 3A —A perspective view of certain embodiments of a modular handguard prior to assembly with an affixed handguard 
           [0021]      FIG. 3B —A perspective view of certain embodiments of a modular handguard prior to assembly with an affixed handguard 
           [0022]      FIG. 3C —A perspective view of certain embodiments of a modular handguard assembled with an affixed handguard 
           [0023]      FIG. 4A —A view of a second end of certain embodiments of a modular handguard 
           [0024]      FIG. 4B —A side view of certain embodiments of a modular handguard 
           [0025]      FIG. 4C —A view of a first end of certain embodiments of a modular handguard 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Certain embodiments of the invention comprise a modular handguard configured to be disposed over a barrel or suppressor component at a distal end of a barrel. Such embodiments of the modular handguard are configured to mate with an affixed handguard. The modular handguard mitigates accidental contact with distal surfaces of a firearm having elevated temperature such as a barrel or suppressor affixed to the firearm. 
         [0027]    It will be appreciated that an affixed handguard may comprise an existing handguard comprising aluminum or steel, or a heat mitigating handguard as disclosed in U.S. application Ser. No. 14/932,924, Heat Mitigating Handguards for Rifles and Method of Manufacture Thereof, to Garst (“the &#39;924 Application”), incorporated by reference in its entirety. 
         [0028]    Certain embodiments comprise a modular handguard comprising a heat mitigating material composition with a low heat transfer coefficient. Certain embodiments of the present invention are manufactured from materials and heat mitigating strategies as disclosed by the &#39;924 Application. Certain embodiments of the present invention may comprise ceramic, polymeric or other materials with a low heat transfer coefficient. 
         [0029]    In certain embodiments of the present invention, as shown in  FIG. 1 , a modular handguard  100  has a hollow form and further comprises an outer form  110  having a first end  111  axially offset from a first end  121  of an inner form  120 . The outer form  110  further comprises an opening  112 . The outer form  110 , spans the entire length of the modular handguard  100 , while the inner form  120  is shorter than the outer form  110 . This results in an offset between the inner form  120  and an outer form  110 , such that the first end  121  of the inner form is inset from the first end  101  of the modular handguard. The outer form  110  further comprises an outer surface  115  and an inner surface  118 . The inner form  120  further comprises an outer surface  125 , coincident with the inner surface  118  of the outer form. 
         [0030]    Shown in  FIG. 2A  and  FIG. 2B , a modular handguard  100  has an inner form  120  of substantially similar cross-sectional profile as an attached handguard  200 . An outer profile dimension  1130  of the inner form  120  ( FIG. 2A ) is substantially similar to an outer profile dimension  2130  of an affixed handguard  200  ( FIG. 2B ). The inner surface  118  of the outer form, referenced in  FIG. 1 , is configured to slidably mate with the outer surface  205  of the attached handguard, referenced in  FIG. 2B . This slidable mating is typically performed with an engineering fit. It will be appreciated that an engineering fit may comprise a running fit, locational clearance fit, RC fit, or other engineering fits such as those specified by ANSI B4.1 (Standard Tolerance Limits and Fits). It will be further appreciated that other engineering fits or assembly strategies known to those skilled in the art may be used while maintaining the inventive spirit of the present invention. 
         [0031]    In certain embodiments of the present invention, as shown in  FIG. 1 , an outer form  110  is offset along a longitudinal axis  105 , from an inner form  120 . As a result, the inner form  120  is inset from a first end  101  of the modular handguard. This inset provides a surface orthogonal to the longitudinal axis  105  of the modular handguard  100  inset from the first end  101  of the modular handguard. This orthogonal surface serves as a mechanical stop  130 . The mechanical stop  130 , inset from the first end  101  of the modular handguard  100 , provides an abutting surface for an affixed handguard  200  ( FIG. 3A-3C ) when mated with the modular handguard  100 . 
         [0032]    Certain embodiments of the present invention, as seen in  FIG. 3A-3C , comprise a modular handguard  100  further comprising a plurality of slide features  140  for interfacing with grooves  220  of an affixed handguard  200 . Slide features  140  provide rotational constraint of the modular handguard  100  about the longitudinal axis  105  when mated to an affixed handguard  200 . It will be appreciated that slide features  140  may comprise other engagement features known to those skilled in the art to provide slidable engagement. It will be further appreciated that the mating of a modular handguard is not limited to a slidable mating and may utilize other mating features known to those skilled in the art. 
         [0033]    Referring to  FIG. 3A  and  FIG. 3B , certain embodiments comprise a modular handguard having apertures  160  through an outer surface  115  of the modular handguard  100 . These apertures  160  are provided for increased ventilation to the modular handguard  100  and a firearm to which the modular handguard  100  is affixed. Such apertures  160  may also be used for fixation purposes by inserting fastening hardware through an aperture  160  to affix an object to the modular handguard  100 . The modular handguard  100  may further comprise threaded apertures  165  for attachment of accessories or peripheral devices using threaded fasteners. It may be desired for a modular handguard  100  to have apertures  160  and threaded apertures  165  configured to match the apertures  160  and threaded apertures  165  of an affixed handguard, as shown in  FIG. 3A . However, some embodiments seen in,  FIG. 3B , have apertures  160  and threaded apertures  165  which differ in configuration from that of the affixed handguard  200 . Threaded apertures  165  may further comprise mechanical interface features such as counter-bores or countersinks. The use of such mechanical interface features may be used to provide increased fixation of a modular handguard  100  to an affixed handguard  200 . The use of such mechanical interface features may also be used to provide increased fixation of accessories or peripheral devices to the modular handguard  100 . 
         [0034]    As shown in  FIG. 3A  and  FIG. 3B , an inner surface  118  of the outer form  110  of the modular handguard  100  is configured to slidably interface with the outer surface  210  of an affixed handguard  200 . In such embodiments, the cross-sectional profile of the internal surface  118  of the outer form  110  of the modular handguard  100 , mimics the cross-sectional profile of the outer surface  210  of the affixed handguard. Furthermore, the slide features  140  mate with grooves  220  in the outer surface  210  of the affixed handguard  200 . This configuration allows the modular handguard  100  to slide over the outer surface  210  of the affixed handguard. The mating of a modular handguard  100  with an affixed handguard  200  provides an extension of the affixed handguard  200 . It will be appreciated that a modular handguard  100  may be configured so the attachment feature  150  of the modular handguard mates with the attachment feature  250  of the affixed handguard so the attachment feature  150  of the modular handguard and the attachment feature  250  of the affixed handguard are contiguous. 
         [0035]    While it will be appreciated that the inner surface  118  of the outer form, referenced in  FIG. 3B , is configured to slidably mate with the outer surface  205  of an attached handguard, it will be further appreciated that the outer surface  115  of the outer form need not mimic the outer surface  205  of the affixed handguard. The outer surface  115  of the outer form and the outer surface  125  of the inner form may be configured independently of an affixed handguard  200 . In certain embodiments, the outer surface  115  of the outer form and the outer surface  125  of the inner form comprise profile shapes and features designed to promote increased airflow for cooling purposes or redirection of muzzle blast away from an operator and the firearm. 
         [0036]    After slidable mating, certain embodiments of the invention (seen in  FIG. 3C ) may be constrained to prevent unintentional disassembly. The constraining of a modular handguard  100  to an affixed handguard  200  may be accomplished with threaded fasteners engaged through an aperture  160  or threaded aperture  165 . When threaded fasteners are threaded through the threaded apertures  165 , the threaded fasteners may be advanced until they contact the outer surface  210  of the affixed handguard  200 . In certain embodiments, threaded fasteners are passed through apertures  160  to engage threaded apertures  165  in the affixed handguard. It will be appreciated that other methods of fixation may be used to constrain a modular handguard  100  to a fixed handguard  200 . Certain methods of fixation may be used to affix a modular handguard  100  to an affixed handguard  200 , which allow an operator to more easily remove a modular handguard  100  from an affixed handguard  200 . Other methods of fixation may be used to affix a modular handguard  100  to an affixed handguard  200 , which provides a more permanent attachment of the modular handguard  100  to an affixed handguard  200 . 
         [0037]    Certain embodiments of the present invention, shown in  FIG. 4A , comprise modular handguard  100  having an overall height  1000  of 6.77 cm (2.667 in) having a profile of a multi-faceted form, such as an octagon, and an attachment feature  150 . Such embodiments further comprise an overall width  1010  of 6.1 cm (2.4 in). The modular handguard  100 , further comprises a hollow form with a substantially circular profile having a radius  1040  of 2.4 cm (0.95 in). Furthermore, such embodiments comprise a first facet width  1030  of 1.98 cm (0.779 in) and a second facet width  1020  of 2.4 cm (0.932 in). It will be appreciated that a modular handguard  100  may comprise other profiles, such as those consistent with the profile of an attached handguard. 
         [0038]    Certain embodiments of the present invention, shown in  FIG. 4B , comprise a handguard having an overall height  1000  of 6.78 cm (2.667 in) and overall length  1070  of 12.7 cm (5.0 in). Other embodiments comprise an overall length  1070  of 22.9 cm (9.0 in). It will be appreciated that the overall length  1070  of the modular handguard may be of any length, but preferably of a length that extends the handguard no further than the muzzle-end of a barrel. It will be further appreciated that the muzzle-end of a barrel may be extended with the addition of a suppressor or other devices which may affix to the muzzle end of a barrel. Such embodiments have an inner form  120  offset from an outer form  110  at an offset length  1080  of 2.54 cm (1.0 in). It will be appreciated that the offset length  1080  may vary. 
         [0039]    Certain embodiments as shown in  FIG. 4B , have apertures  160  and threaded apertures  165  through an outer surface  115  of the modular handguard. In certain embodiments, the aperture distance  1110  between a first and second aperture  160  is 2.54 cm (1.0 in). The distance between threaded apertures  165  and an adjacent aperture  160  is 1.23 cm (0.485 in). 
         [0040]    Certain embodiments, as shown in  FIG. 4C , comprise an octagonal profile with an outer form  110  having an internal width  1130  of 5.50 cm (2.164 in), and a facet width  1180  of 1.78 cm (0.7 in). Such embodiments further comprise slide features  140  having a tapered form with a top width  1160  of 0.295 cm (0.116 in), a height  1190  of 0.24 cm (0.094 in), and a base fillet radius  1170  of 11 mm (0.042 in). Such embodiments have an opposing slide feature spacing  1150  of 5.16 cm (2.03 in) and opposing facet distance  1130  of 5.50 cm (2.164 in). It will be appreciated that such embodiments are configured to slidably mate with an affixed handguard. The above disclosed dimensions may vary dependent upon the affixed handguard for which the modular handguard  100  is configured to engage with. 
         [0041]    While various embodiments of the present invention have been described in detail, it is apparent that modifications and alterations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and alterations are within the scope and spirit of the present invention. Further, the inventions described herein are capable of other embodiments and of being practiced or of being carried out in various ways. In addition, it is to be understood that the phraseology and terminology used herein is for the purposes of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” or “adding” and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof, as well as, additional items