Patent Publication Number: US-9845938-B1

Title: Shock absorbing flashlight

Description:
BACKGROUND AND SUMMARY 
     When a flashlight is dropped, the resulting abrupt impact with a hard surface can damage both the external and internal parts of the flashlight. That is, the impulse applied to a flashlight upon impact can break the lens, light source, light switch and casing, as well as damage the batteries and internal electrical circuits. While some flashlights have been provided with resilient covers, none is known to be able to withstand the impact from a fall of up to 100 feet. 
     This disclosure is directed to a shock absorbing system for a flashlight and to a flashlight fitted with the shock absorbing system that can withstand the impact from a fall of up to 100 feet. Potentially damaging impacts are absorbed from all directions with a shock absorbing system that includes an external shock absorber on both the head or front portion of a flashlight and on the tail or rear portion of a flashlight. Each external shock absorber includes a series of axially-extending flexible fins which are designed to resiliently flex and bend upon impact so as to reduce impact impulses and provide a more gradual deceleration of the flashlight. The flexing and bending of the fins dampens the impact by providing a predetermined distance over which the fins can deform while absorbing, distributing and dissipating the kinetic energy of a falling flashlight. 
     This absorption of energy by resilient deformation of the fins can be augmented with the provision of an optional axial and radial clearance zone around each end of a flashlight. These open clearance spaces allow for additional deflection of the fins and provide a space through which impacts and impulse forces are absorbed by additional resilient deformation of a series of circumferentially-spaced-apart fins. In effect, an annular “safety zone” or “crumple zone” is formed around the front crown of a flashlight as well as around the rear tail cap of a flashlight. That is, in one embodiment, before any contact occurs between the fins and the flashlight, the fins resiliently deflect over a predetermined distance so as to absorb shock forces. In this manner, reduced shock forces are transferred to the flashlight. 
     Additional shock absorbing protection is provided on both the front and rear shock absorbers in the form of axially-extending resilient ribs which protrude radially outwardly away from the body of a flashlight. In this manner, the ribs make first contact with any impact surface before any contact is made against the underlying flashlight body or casing. In one embodiment, the ribs can extend axially into each respective fin so as to provide supplemental support to each fin and to further distribute impact forces over a larger surface area around the flashlight casing. 
     In the case of the front shock absorber, the bottom of the fins are formed with radially-inwardly extending engagement surfaces which overlie the leading circular edge of the flashlight crown. The engagement surfaces can be homogeneously molded with a front annular flange having a bottom wall axially spaced over the edge of the flashlight crown. In this manner, impact forces are first absorbed by deformation of the fins and then reduced forces are distributed circumferentially around the flashlight crown by the front annular flange and a cylindrical front side band which interconnects the fins and spaces the front shock absorber from the flashlight crown. 
     The front annular flange and the cylindrical front side band tend to distribute impact forces circumferentially around the flashlight crown so as to reduce localized stresses adjacent the point of first contact between the front of the flashlight and the ground or any other hard impact surface. This cushioning is effective for absorbing both axial and radial impact forces applied to the front shock absorber. An annular resilient rubber or elastomeric cap can be provided between the bottom of the front fins and the top edge of the flashlight crown to further absorb and distribute impact forces around the flashlight crown. 
     Impact forces received by the fins and circumferentially distributed by the front annular flange and the front side band are further absorbed by the axially-extending ribs which can be molded homogeneously with the front fins, front annular flange and front side band. The ribs can extend radially outwardly from the outer surface of the front side band and extend axially from the front fins to a rear annular or cylindrical band which surrounds and grips a rear portion of the flashlight head portion. The rear band anchors the front shock absorber on the flashlight crown. 
     With the ribs interconnecting the front and rear bands, forces received by the fins are transferred to the front side band and also to the rear band via the axially-extending ribs to further dissipate shock throughout the front shock absorber. That is, the rear band can circumferentially grip the flashlight body and further distribute forces to a portion of the flashlight axially spaced rearwardly from the front side band. 
     Because the ribs extend radially outwardly from the flashlight body, they protect the underlying side walls of the flashlight body from the shocks applied radially to the flashlight. The ribs can be dimensioned to either extend in contact with the underlying flashlight body and/or overlie the underlying flashlight body with a small clearance. In one embodiment, a clearance space between the ribs and the flashlight body allows the ribs to flex radially inwardly and absorb shock prior to transferring radial shock forces to the flashlight body. 
     The rear band is designed to radially grip and clamp around the rear crown portion of a flashlight. This can be achieved by forming the front shock absorber in two generally semi-cylindrical half shells. The half shells can be clamped together with any suitable fasteners such as screws, rivets or with an integrally formed snap fit connection. A tongue and groove connection can also be molded into the contacting surfaces of each half shell to provide an axially-sliding friction connection therebetween. Adhesive bonding can also be used. 
     Modern high intensity flashlights can generate a significant amount of heat around the flashlight crown which houses one or more incandescent bulbs or one or more light emitting diodes (LEDs). In order to allow for the efficient transfer of heat from the flashlight crown to ambient, the ribs are spaced apart with large open spaces between them to allow direct contact between the flashlight crown and the surrounding ambient air. Such open spaces are not as necessary around the cooler tail end of the flashlight. 
     The rear shock absorber has a structure similar to the front shock absorber. A series of rear fins projects axially rearwardly from the rear shock absorber to absorb both axial and radial impact forces applied to the tail portion of a flashlight. The rear fins are supported on an end cap formed with a cylindrical side wall and an annular end wall. The end wall extends radially inwardly from the side wall to a central axially-raised circular wall surrounding a circular opening. An elastic or rubber thimble cap serving as a switch cover and switch actuator extends rearwardly through the circular opening from within the end cap for actuating an on-off switch mounted on the tail of the flashlight. 
     As with the front shock absorber, the rear shock absorber is provided with a series of circumferentially-spaced-apart radially-projecting ribs which extend along the cylindrical side wall of the rear shock absorber. An axial and radial clearance fit can be provided between the end cap and the rear or tail portion of a flashlight. The ribs can extend from the fins as described above. 
     The rear shock absorber can also be mounted to the tail of a flashlight with a simple friction fit or with a separate locking ring. The locking ring can be formed as a frustoconical or axially tapered band which encircles and radially grips the tail of a flashlight. Axially-extending locking tabs are formed on the locking ring to engage the inner end of the cylindrical side wall of the end cap with one or more snap fit connections. External ribs can be formed on the locking ring to match and align with the ribs on the end cap. Axial and radial clearances can be maintained between the rear shock absorber and the rear portion of the flashlight to provide a “safety zone” similar to that provided around the front portion of the flashlight. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a rear perspective view of a representative embodiment of a flashlight fitted with front and rear shock absorbers; 
         FIG. 2  is a central axially-sectioned view of the front portion of the flashlight of  FIG. 1 ; 
         FIG. 3  is a rear end perspective view of the rear end cap of  FIG. 1 ; 
         FIG. 4  is a rear perspective view of the locking ring of  FIG. 1 ; 
         FIG. 5  is a front perspective view of the end cap of  FIG. 3 ; 
         FIG. 6  is a side perspective view in axial section through the center of the rear shock absorber; 
         FIG. 7  is a rear perspective view in central axial section of the flashlight of  FIG. 1  with a front portion of the flashlight modified as shown in  FIG. 8 ; and 
         FIG. 8  is a view similar to  FIG. 2  showing the ribs of the front shock absorber in direct contact with the outer surface of the front portion of the flashlight. 
     
    
    
     DESCRIPTION OF REPRESENTATIVE EMBODIMENTS 
     As shown in  FIG. 1 , a flashlight  10  includes a front portion  12 , a central portion  14  and a rear portion  16 . A front shock absorber  18  is provided on the front portion  12  and a rear shock absorber  22  is provided on the rear portion  16 . The central portion  14  extends between the front and rear portions and can include a grooved outer gripping surface, such as a spiral grooved portion  26  which can be provided as a sleeve or plastic molded portion over an underlying tubular body  28 . 
     The front shock absorber  18  and the rear shock absorber  22  can be formed of a flexible, elastic resilient material for absorbing shock and impact forces applied to the flashlight  10 . In one embodiment, the front and rear shock absorbers  18 ,  22  can be homogeneously molded or otherwise formed from a rubber or plastic material. Nylon and high density polyethylene plastics has been found to be well suited for this application. As seen in  FIG. 1 , the front shock absorber  8  forms a protective open cage structure around the front portion  12  of the flashlight  10 . 
     The flashlight  10  has a central axis  31  from which axial and radial directions are referenced. As further shown in  FIGS. 1 and 2 , the front shock absorber  18  includes a series of circumferentially-spaced-apart bumpers in the form of axially-forwardly projecting thin-walled fingers or fins  30 . Each fin  30  can include a base portion  32  extending axially upwardly from a bottom wall portion  34  to an arched apex or tip portion  35 . A radially inwardly and axially-rearwardly sloping edge  37  can extend from the tip portion  35  to the bottom wall portion  34 . Bottom wall portion  34  can be formed as an annular radial flange  36  forming a circular aperture over the front portion  12 . The circular aperture provides an opening for the passage of illuminating light from within the front portion  12 . 
     The bottom wall portion  34  extends radially inwardly above an upper leading edge  38  on a front crown portion  40  of the flashlight  10 . A clearance space  44  can be provided between the bottom of the radial flange  36  and the upper edge  38  of the crown portion  40 . The crown portion  40  may be formed of a rigid plastic or metal material. However, an aluminum material has been found to be well suited for this function due to its ability to conduct heat efficiently from the crown portion  40  to ambient so as to avoid undesirably high temperatures in the crown portion  40 . 
     The clearance space  44  can extend axially over a distance  46  from about one tenth of a millimeter to several millimeters. The cylindrical clearance space  44  provides a crush zone or safety zone over which the fins  30  can axially deflect rearwardly and inwardly upon receiving an axial or radial impact force. That is, the resilient bending of the fins  30  absorbs and dissipates a significant amount of kinetic energy before making contact, if any, with the crown portion  40  of the flashlight  10 . This provides significant protection to the flashlight. 
     In the embodiment of  FIG. 2 , a soft resilient rubber, elastomeric or spongy annular bezel cap  45  can be provided around and over the upper edge  38  of the front crown portion  40 . Cap  45  can be molded from silicone rubber directly on the crown portion  40  or applied as a coating or stretchable sleeve over the crown portion  40 . Localized forces applied to the front shock absorber  18  are transferred to and absorbed and spread out through the cap  45  over a larger surface area of the front portion  12  by compression of the cap  45  caused by the deflection of shock absorber  18 . 
     The cap  45  can include an annular radial lip  47  extending radially over a flashlight lens retainer sleeve  50  which is press fit or threaded into the front crown portion  40  along interface  51 . The lens retainer sleeve  50  secures a lens (not shown) within a lens mounting groove  49 . A small axial clearance  53  can be provided between the top surface of the cap  45  and the bottom wall portion  34 . Alternatively, the axial clearance can be eliminated and the bottom wall portion  34  can engage the cap  45  with a light elastic compression fit. 
     It should be noted that even if only one or two fins  30  are forcefully impacted, the impact force is distributed circumferentially through the annular radial flange  36  all the way around and through the front shock absorber  18 . That is, a cylindrical front band  48  ( FIG. 1 ) extends axially rearwardly or downwardly from the radial flange  36  and receives impact forces transmitted from the fins  30  and the radial flange  36 . 
     As further seen in  FIG. 2 , the front band  48  ( FIG. 1 ) can be dimensioned to surround the crown portion  40  of the flashlight  10  with an annular or cylindrical radial clearance space  52 . This establishes a radial crush zone or safety zone around the outside of the crown portion  40  through which the front band  48  will deflect and absorb impact energy from the fins  30  and/or directly from impact with the front band  48 . The radial clearance space  52  can extend radially from about one millimeter to about one centimeter between the crown portion  40  and the front band  48 , as indicated by spacing arrows  54 . In an alternate embodiment, the front band  48  can make contact with and radially embrace the crown portion  40  without a clearance space  52 , such as shown in  FIG. 8 . 
     Additional shock absorption and impact protection is provided around the front portion  12  of the flashlight  10  by a circumferentially spaced apart series of ribs  60 . Each rib  60  can extend axially rearwardly from the base portion  32  of each fin  30  to a rear cylindrical band  64  ( FIG. 1 ). Large open spaces  66  are provided between each pair of adjacent ribs and the front and rear bands  48 ,  64 . In the example shown in  FIG. 1 , the open spaces  66  completely surround the front portion  12  and expose more than about half and preferably up to about 90 percent of the outer surface area of the front portion  12 . 
     The open spaces  66  allow for direct contact between the surrounding ambient air and the outer surface of the front portion  12  of the flashlight  10 . Advantageously, more than half of the surface area of the front portion  12  is exposed by the open spaces  66  allowing for effective convective cooling around the front portion  12 . Stated otherwise, more than half of the envelope of the front shock absorber is open to ambient when mounted on the front portion  12  of the flashlight  10 . This helps to prevent excessive heating of the front crown portion  40 . 
     As further seen in  FIG. 2 , an annular or cylindrical clearance space  70  can be maintained between the radially inner surfaces  68  of the ribs  60  and the outer surface  62  of the front portion  12  of the flashlight  10 . As described above with respect to the radial clearance space  52 , clearance space  70  provides a radial crush zone or safety zone through which the ribs  60  can resiliently radially deflect and dissipate impact energy before contacting the outer surface  62  of the front portion  12 . In an alternate embodiment, the ribs  60  can make contact with and embrace the front portion  12  of the flashlight  10  without a clearance space. 
     In yet another embodiment, the soft rubbery annular cap  45  can be formed with elongated tubular sidewalls  71  that extend axially over substantially the entire length of the front crown portion  40  so as to fill the radial clearance spaces  52 , 70  with energy absorbing resilient material, such as silicone rubber. The tubular sidewalls  71  can be provided separately from the cap  45  as a molded elastic sleeve. In either case, the tubular sidewalls  71  allow for the inward radial deflection of the ribs  60 , while providing additional shock absorption and distribution of impact forces. 
     The bottom portions  72  of a pair of diametrically opposed ribs  60  can be provided with connectors  74  for mounting the front shock absorber  18  on the front portion  12  of the flashlight  10 . Similar connectors  78  can be provided on the top portions  80  of these ribs or on the fins  30  as shown. The connectors  74  can be formed as flanges with simple through holes  75  through which a fastener  84  extends. 
     In the embodiment shown in  FIGS. 1 and 2 , the front shock absorber  18  is formed as a pair of homogeneously molded mirror image half shells  88 ,  90 . The half shells  88 ,  90  are anchored or clamped around the lower end of the front portion  12  of the flashlight  10  via the connectors  74 ,  78 . A threaded fastener, rivet or any other suitable fastener can be used to clamp together and hold the half shells  88 ,  90  in a securely fixed position on the front portion  12  of the flashlight  10 . Other types of connectors can be used to hold the half shells together such as pin and socket connectors, snap fit connectors, dovetail connections and adhesive bonds. 
     It is also possible to lightly clamp the half shells  88 ,  90  to the front portion  12  with a light frictional clamping force so that upon impact, the front shock absorber  18  can frictionally rotate around the front portion  12  and thereby dissipate some of the impact force through friction. Alternatively, the front shock absorber can be molded as a single stretchable shell which can be stretched over the front portion  12  in the manner of a sock or molded directly over the front portion  12  as an insert molded assembly. 
     Additional flexibility, resilience and shock absorption can be provided around the front portion  12  of the flashlight  10  by forming openings in the ribs  60 . For example, as seen in  FIG. 2 , elongated slots  92  allow the ribs  60  to flex radially inwardly so as to compress the slots  92  and absorb additional impact energy. As further shown in  FIG. 2 , the front portion  12  of the flashlight  10  can be removably secured to the central portion  14  via a threaded interconnection  96 . An O-ring  98  is clamped between the front and central portions  12 ,  14  for sealing against water and other liquids. 
     As further seen in  FIGS. 1, 3 and 4 , the rear shock absorber  22  can include a cup-shaped end cap  100  secured to the rear portion  16  of flashlight  10  with a locking ring  102 . The end cap  100  and locking ring  102  can be formed of the same material as the front shock absorber  18 . That is, they can be each homogeneously molded of a rubber or plastic material such as nylon plastic. 
     The end cap  100  includes a cylindrical side wall  106 . An annular end wall  108  extends radially inwardly from the rear end of the side wall  106  to an annular axially-extending end flange  110 . The end flange  110  encircles a central opening  112  which extends through the end wall  108 . 
     In a manner similar to the front shock absorber  18 , a series of radially-rearwardly extending thin walled fins  116  project rearwardly and radially-outwardly from the annular end wall  108  for absorbing impact forces around the rear portion  16  of the flashlight  10 . A series of axially and radially extending ribs  118  is formed along the side wall  106  of the end cap  100 . The ribs  118  extend rearwardly into the fins  116  for absorbing axial and radial impacts around the rear portion  16  of the flashlight  10 . 
     As shown in  FIG. 5 , the end cap  100  has an inner side wall  120  formed with a circumferentially-spaced series of radial grooves  124  leading axially into radially undercut ledges  126  for receiving resilient locking hooks  130  ( FIG. 4 ) on the locking ring  102 . The locking hooks  130  extend axially into the grooves  124  and snap radially-outwardly over the ledges  126  into the radial undercut pockets  134  adjacent and under the ledges  126 . 
     As further shown in  FIG. 4 , the locking ring  102  includes a fructoconical side wall  136  having a series of circumferentially-spaced radially-outwardly extending ribs  138 . The ribs  138  are arranged to align with and abut the ribs  118  on the end cap  100  when the end cap is fitted over the end portion  16  of the flashlight  10 . That is, the end cap  100  is locked onto the rear portion  16  of the flashlight  10  by pushing the end cap  100  axially forwardly so that the grooves  124  align with the locking hooks  130  causing the resilient locking hooks  130  to deflect radially inwardly and then snap radially outwardly into the undercuts  134 . 
     The locking ring  102  can be located on the rear end portion  16  of the flashlight  10  by unscrewing or otherwise removing the front portion  12  from the central portion  14  and sliding the locking ring  102  over the central portion  14  until the locking ring engages a radially enlarged abutment surface on the end portion  16 . This axial abutment secures the locking ring  102  in place on the rear portion  16  of the flashlight  10 . The end cap  100  can then be connected to the locking ring  102  as described above and as further shown in  FIG. 6 . 
     Additional structural details of the flashlight  10  and front and rear shock absorbers are shown in  FIG. 7  wherein a rubber or plastic switch cover  142  is axially movable through the central opening  112  in the end cap  100  for actuating an on-off switch located within the rear end portion  16  of the flashlight  10 . 
     It should be noted that any or all of the shock absorbing resilient material which is directly carried on the surface of the flashlight  10  including the front and rear shock absorbers  18 ,  22 , the bezel cap  45  and any tubular extension thereof and the spiral grooved portion  26  can be molded onto the flashlight  10  such as by conventional insert molding. Alternatively the front shock absorber  18  can be mounted as described above over an insert molded subassembly with the tubular sleeve  71  molded over the crown portion  40  as described above or applied as an additional insert molded part over the subassembly as a second “shot” or molding in a two shot injection mold or in a separate injection mold. 
     In yet another embodiment, the front and rear shock absorbers  18 , 22  can be molded directly to the flashlight  10  by insert molding with or without any intervening softer shock absorbing material provided therebetween. 
     The embodiment of  FIG. 8  is similar to that of  FIGS. 1 and 2 , but eliminates the axial and radial clearances or crush spaces  53 ,  54  and the slots  92 . 
     It will be appreciated by those skilled in the art that the above shock absorbing flashlight is merely representative of the many possible embodiments of the disclosure and that the scope of the disclosure should not be limited thereto.