Abstract:
Protective helmet comprising a two piece shell, an electric motor and impeller useful for creating a positive pressure environment in the head space, and a filter for removing particulates and other substances. The impeller introduces atmospheric air into an air channel defined by two detachably attached shell pieces. The air is pushed through a particulate filter in the air channel and then through at least one aperture into the head space. A heating element may be used to heat the air flow.

Description:
RELATED APPLICATIONS 
   The present application is related to a U.S. patent application entitled “Positive Pressure Protective Helmet” by the same inventor and filed on an even date herewith. 
   The present application is also related to a U.S. patent application entitled “Protective Helmet with Detachable Shell Piece” by the same inventor and filed on an even date herewith. 
   The entire disclosures of the above mentioned applications are hereby incorporated by reference in their entirety. 
   FIELD OF THE INVENTION 
   The present invention relates generally to protective helmets. More particularly, the present invention relates to protective helmets for use when operating recreational vehicles. 
   BACKGROUND OF THE INVENTION 
   In the field of recreational vehicles (e.g., motorcycles, all terrain vehicles (ATVs), snowmobiles, sport trucks, dune buggies, sandrails, and the like) protective helmets are often worn to protect the user&#39;s head. Particulates such as sand and dust may enter the helmet during use and interfere with the user&#39;s ability to operate the vehicle. The more particulates a helmet keeps away from the user&#39;s face and eyes, the more comfortable the user will be. Even a few particulates in a user&#39;s eye may cause great discomfort. 
   Protective helmets are typically subjected to standardized performance tests to ensure the user is as safe as possible if a collision occurs. The Department of Transportation (DOT) and Snell are two major organizations that set safety standards for crash-helmets in the United States. DOT sets minimum standards for all helmets designed for motorcyclists and other motor vehicle users. The standard is Federal Motor Vehicle Safety Standard 218 and is codified at 49 C.F.R. § 571.218. The Snell 2000 Standard for Protective Headgear establishes performance characteristics for helmets for use in open motorized vehicles such as motorcycles, ATVs, and snowmobiles. 
   The DOT subjects crash-helmets to an impact attenuation test. Impact attenuation is determined by measuring the acceleration experienced by a helmeted test headform during a collision. The helmeted headform is dropped on both a hemispherical and flat steel anvil. The height for the helmet and test headform combination fall onto the hemispherical anvil is set so that the impact speed is 5.2 m/sec. The minimum drop height is 138.4 cm. The guided freefall drop height for the helmet and test headform combination unto the flat anvil is set so that the minimum impact speed is 6.0 m/sec, with a minimum drop height of 182.9 cm. 
   When an impact attenuation test is conducted as described above, the following criteria are used to determine if a helmet passes; the test headform must not experience a peak acceleration over 400 G, accelerations in excess of 200 G must not exceed a cumulative duration of 2.0 milliseconds, and accelerations over 150 G must not exceed a cumulative duration of 4.0 milliseconds. The Snell impact management test involves a series of controlled impacts. First, the helmet is positioned on a head test platform. The helmeted headform is then dropped in guided falls onto test anvils. The impact energy must be a minimum of 150 Joules. If the peak acceleration imparted to the headform exceeds 300 G, the helmet fails. 
   SUMMARY OF THE INVENTION 
   A protective helmet in accordance with an exemplary embodiment of the present invention comprises a first shell piece defining a head space and at least one aperture communicating with the head space. In one aspect of this exemplary embodiment, a blower may communicate with the aperture via a channel defined in part by a second shell piece that is detachably attached to the first shell piece at an interface. In an additional aspect of this exemplary embodiment, the second shell piece selectively covers the at least one aperture while the second shell piece is attached to the first shell piece. In certain advantageous implementations, the at least one aperture has a maximum span of less than about 13.0 millimeters. 
   In one feature of the present invention, the blower may be used to provide a positive pressure environment. When the protective helmet is used in conjunction with recreational vehicles (e.g., motorcycles, all terrain vehicles (ATVs), snowmobiles, sport trucks, dune buggies, sandrails, and the like), this positive pressure environment may preclude particulates from entering the head space. Examples of particulates that may be encountered when operating a recreational vehicle include sand, dust, dirt, snow, water droplets, and ice crystals. The more particulates a helmet keeps away from the user&#39;s face and eyes, the more comfortable the user will be. 
   In certain advantageous implementations of the present invention, the second shell piece is detachably attached to the first shell piece at an interface. In some advantageous implementations of the present invention, the first shell piece has sufficient strength to pass the DOT and Snell impact management tests whether or not the second shell piece is detachably attached. This may be accomplished by providing a wall of first shell piece having a desired combination of material strength and wall thickness. 
   In some exemplary implementations, the second shell piece defines the top portion of a channel while the second shell piece is detachably attached to the first shell piece. In an exemplary implementation, the second shell piece comprises a first edge flange and a second edge flange. The flanges preferably contact the first edge and second edge of the first shell piece to help detachably attach the first shell piece and the second shell piece. The second shell piece also comprises an intermediate portion which has a curved shape in lateral cross-section and which extends between the first edge flange and the second edge flange 
   The blower assembly may comprise an electric motor AND an impeller. The electric motor rotateS an impeller which introduces atmospheric air into the air channel defined by the first shell piece and the second shell piece, through the air filter, through the at least one aperture defined by the first shell piece, and into the head space defined by the first shell piece, creating a positive pressure environment useful for reducing particulate entry into the head space. The electric motor may be powered by at least one battery housed inside or outside the protective helmet. A heating element may be included in some implementations of the present invention. The heating element may be powered by the battery and placed in contact with the air stream to warm the air stream during cold weather usage of the protective helmet to reduce fogging of the face shield. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a helmet in accordance with an exemplary embodiment of the present Invention. 
       FIG. 2  is an additional perspective view of helmet shown in the previous figure. 
       FIG. 3  is a plan view of a helmet in accordance with an exemplary embodiment of the present invention. 
       FIG. 4  is an additional plan view of helmet shown in the previous figure. 
       FIG. 5  is an additional plan view of helmet shown in the previous figure. 
       FIG. 6  is an exploded assembly view of a helmet in accordance with an exemplary embodiment of the present invention. 
       FIG. 7  is a cross sectional view of a helmet in accordance with the present invention. 
       FIG. 8  is a plan view of a back side of a protective helmet in accordance with an exemplary embodiment of the present invention. 
       FIG. 9  is a partial cross sectional view of a helmet in accordance with an exemplary embodiment of the present invention. 
       FIG. 10  is a partial cross sectional view of a helmet in accordance with an exemplary embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Accordingly, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. 
     FIG. 1  is a perspective view of a helmet  100  in accordance with an exemplary embodiment of the present invention. Helmet  100  comprises a first shell piece  102  defining a front opening  104 . First shell piece  102  may advantageously include an inner shell comprising an energy absorbing material and an outer shell. The inner shell of first shell piece  102  may define a head space. In the embodiment of  FIG. 1 , a shield  106  is disposed over front opening  104 . Also in the embodiment of  FIG. 1 , helmet  100  includes a visor  108 . Visor  108  and shield  106  are preferably detachably attached to first shell piece  102  of helmet  100 . 
     FIG. 2  is an additional perspective view of helmet  100  shown in the previous figure. In the embodiment of  FIG. 2 , visor  108  has been detached from first shell piece  102 . In  FIG. 2  it may be appreciated that helmet  100  includes a second shell piece  120 . In some advantageous embodiments of the present invention, second shell piece  120  is detachably coupled to first shell piece  102  at an interface  122 . In the embodiment of  FIG. 2 , interface  122  comprises a plurality of fasteners  124 . Various types of fasteners may be utilized without deviating from the spirit and scope of the present invention. Examples of fasteners that may be suitable in some applications include hook and loop fasteners, snaps, pins, rivets, screws, and adhesives. 
   In  FIG. 2 , it maybe appreciated that second shell piece  120  comprises a front flange  126 , a first edge flange  128 , and a second edge flange  130 . An intermediate portion  132  of second shell piece  120  is shown extending between first edge flange  128  and second edge flange  130 . In some embodiments of the present invention, intermediate portion  132  of second shell piece  120  has a curved shape in lateral cross-section. In the embodiment of  FIG. 2 , an outer surface of each flange is substantially flush with an outer surface  136  of first shell piece  102 . 
     FIG. 3  is a plan view of a helmet  100  in accordance with an exemplary embodiment of the present invention. Helmet  100  comprises a first shell piece  102  and a second shell piece  120 . In the embodiment of  FIG. 3 , first shell piece  102  and second shell piece  120  define an air flow channel  138 . 
   In  FIG. 3  a portion of a blower  140  can be seen extending beyond second shell piece  120 . In an advantageous embodiment of the present invention, blower  140  is adapted draw air from the atmosphere  142  surrounding helmet  100 . This air may be blown through flow channel  138  and may enter a head space  146  of helmet  100  via one or more apertures defined by first shell piece  102 . In some advantageous embodiments of the present invention, blower  140  is capable of producing an air flow through flow channel  138  that is sufficient to provide a positive pressure inside head space  146 . In these advantageous embodiments, the positive pressure inside head space  146  is preferably greater than an ambient pressure found in atmosphere  142  outside of first shell piece  102 . 
   In the embodiment of  FIG. 3 , blower  140  comprises a motor  150  which may be used to turn an impeller. In the embodiment of  FIG. 3 , a battery pack  152  is coupled to motor  150  of blower  140  via a cable  154 . Battery pack  152  may be worn, for example, clipped to the belt of a rider. In the embodiment of  FIG. 3 , blower  140  is disposed proximate a back side  156  of first shell piece  102 . In  FIG. 3 , it may be appreciated that blower  140  is disposed proximate a bottom extent  158  of first shell piece  102 . 
     FIG. 4  is an additional plan view of helmet  100  shown in the previous figure. In the embodiment of  FIG. 4 , second shell piece  120  has been separated from first shell piece  102 . The previous position of second shell piece  120  is illustrated with a dashed line in FIG.  4 . Thus, in  FIG. 4  it may be appreciated that second shell piece  120  and first shell piece  102  cooperate to define flow channel  138 . 
   In  FIG. 4  it may be appreciated that first shell piece  102  defines a trough  160 . An outer shell  166  of first shell piece  102  defines a plurality of apertures  162  that fluidly communicate with flow channel  138 . In some advantageous embodiments of the present invention, apertures  162  are dimensioned such that they will not allow objects having a particular size to pass into head space  146  defined by first shell piece  102 . In some embodiments, for example, the maximum span of each aperture  162  is less than about 13.0 millimeters. 
     FIG. 5  is an additional plan view of helmet  100  shown in the previous figure. An inner shell  170  of first shell piece  102  is visible in FIG.  5 . In some advantageous embodiments of the present invention inner shell  170  comprises an energy absorbing material. In the embodiment of  FIG. 5 , inner shell  170  of first shell piece  102  defines a head space  146 . In  FIG. 5  it may be appreciated that inner shell  170  of first shell piece  102  defines a plurality of lumens  174 . Each lumen  174  preferably communicates with an aperture defined by an outer shell  166  of first shell piece  102 . 
   In  FIG. 5  it may be appreciated that second shell piece  120  comprises a front flange  126 , a first edge flange  128  and a second edge flange  130 . An intermediate portion  132  of second shell piece  120  is shown extending between first edge flange  128  and second edge flange  130 . In some embodiments of the present invention, intermediate portion  132  of second shell piece  120  has a curved shape in lateral cross-section. In the embodiment of  FIG. 5 , second shell piece  120  also includes a front flange  126 . In  FIG. 5 , it may be appreciated that an outer surface of each flange is substantially flush with an outer surface  136  of first shell piece  102 . 
     FIG. 6  is an exploded assembly view of a helmet  200  in accordance with an exemplary embodiment of the present invention. Helmet  200  of  FIG. 6  includes a blower  240 . In the embodiment of  FIG. 6 , blower  240  comprises a motor  250  for turning an impeller  276 . In the embodiment of  FIG. 6 , impeller  276  is disposed within a shroud  278 . Also in the embodiment of  FIG. 6 , a filter frame  280  is coupled to blower  240 . 
   Helmet  200  also includes a filter sock  282  defining a cavity  284  that is preferably dimensioned to receive filter frame  280 . A proximal end of filter sock  282  may be fixed around the circumference of blower  240  using an elastic ring  286 . Blower  240  may be advantageously utilized to create an air stream flowing through filter sock  282 . Filtered air may then enter a head space  246  defined by a first shell piece  202  of helmet  200 . A second shell piece  220  may be selectively coupled to first shell piece  202  utilizing a plurality of fasteners  224 . In the embodiment of  FIG. 6 , each fastener  224  has a shaft  290 . 
     FIG. 7  is a cross sectional view of a helmet  300  in accordance with the present invention. In the embodiment of  FIG. 7 , a filter sock  382  is disposed within a flow channel  338  defined by a first shell piece  302  and a second shell piece  320 . In  FIG. 7 , it may be appreciated that an outer shell  366  of first shell piece  302  defines an aperture  362  that provides fluid communication between flow channel  338  and a head space  346  defined by an inner shell  370  of first shell piece  302 . Inner shell  370  defines a lumen  392  in the embodiment of FIG.  7 . 
   In some advantageous implementations, flow channel  338  is shaped to provide smooth airflow with relatively low back pressure. In the embodiment of  FIG. 7 , the lateral cross sectional area of flow channel  338  gradually decreases along an air path extending from blower  340  to aperture  362 . Also in the embodiment of  FIG. 7 , flow channel  338  has a radius of curvature similar to a dimension of a human head. 
   A filter sock  382  defining a cavity  384  is shown disposed within flow channel  338 . A proximal end of filter sock  382  is shown fixed around the circumference of blower  340  by elastic ring  386 . In  FIG. 7  an air stream  394  is shown passing through filter sock  382 . Blower  340  may be advantageously utilized to draw air from an atmosphere  342  surrounding helmet  300  and push this air through filter sock  382 . Filtered air may then enter a head space  346  defined by a first shell piece  302 . 
   In some advantageous embodiments of the present invention inner shell  370  of first shell piece  302  comprises an energy absorbing material. In the embodiment of  FIG. 7 , inner shell  370  defines a head space  346 . In  FIG. 7  it may be appreciated that inner shell  370  defines a lumen  392  that fluidly communicates with aperture  362 . 
   In  FIG. 7 , it may be appreciated that second shell piece substantially covers aperture  362  while second shell piece  320  is attached to first shell piece  302 . In certain advantageous embodiments, first shell piece  302  has sufficient strength to pass the DOT and Snell impact management tests whether or not the second shell piece  320  is detachably attached. This may be accomplished by providing a wall  396  of first shell piece  302  having a desired combination of material strength and wall thickness. 
   In the embodiment of  FIG. 7 , first shell piece  302  defines a trough  360  that is dimensioned to receive second shell piece  320 . Also in the embodiment of  FIG. 7 , second shell piece  320  includes a front flange  326 . Trough  360  of first shell piece  302  includes a shoulder  398  that is dimensioned such that front flange  326  of second shell piece  320  rests on shoulder  398  of trough  360  while second shell piece  320  is attached to first shell piece  302 . 
   In  FIG. 7 , it may be appreciated that shoulder  398  of trough  360  is located at a depth corresponding to a thickness of front flange  326  of second shell piece  320 . Accordingly, an outer surface of front flange  326  is substantially flush with an outer surface  336  of the first shell piece  302  in the embodiment of FIG.  7 . 
     FIG. 8  is a plan view of a back side  456  of a protective helmet  400  in accordance with an exemplary embodiment of the present invention. In the embodiment of  FIG. 8 , a second shell piece  420  of protective helmet  400  includes a housing  488  that is dimensioned to receive a blower  440 . Second shell piece  420  and a first shell piece  402  define a flow channel  438 . Blower  440  may be arranged to urge a stream of air through flow channel  438  and into a head space  446  of helmet  400 . 
   A plurality of fasteners  424  are visible in FIG.  8 . Fasteners  424  may be utilized to selectively attach second shell piece  420  to first shell piece  402 . In some advantageous embodiments of the present invention, blower  440  is fixed to second shell piece  420 , and blower  440  is free from attachment to first shell piece  402 . In these advantageous embodiments, blower  440  separates from first shell piece  402  when second shell piece  420  is separated from first shell piece  402 . 
     FIG. 9  is a partial cross sectional view of a helmet  500  in accordance with an exemplary embodiment of the present invention. Helmet  500  includes a first shell piece  502  comprising an outer shell  566  and an inner shell  570 . In  FIG. 9 , it may be appreciated that first shell piece  502  defines a head space  546 . In the embodiment of  FIG. 9 , first shell piece  502  defines a trough  560  that is dimensioned to receive a second shell piece  520 . In  FIG. 9  it may be appreciated that second shell piece  520  and first shell piece  502  define a flow channel  538 . 
   In  FIG. 9  it may be appreciated that second shell piece  520  is attached to first shell piece  502  at an interface  522 . In the embodiment of  FIG. 9 , interface  522  comprises a strip  544  that is disposed between first shell piece  502  and second shell piece  520 . In some advantageous embodiments of the present invention, strip  544  provides a water tight seal between first shell piece  502  and second shell piece  520 . Strip  544  may comprise various elements without deviating from the spirit and scope of the present invention. Examples of elements that suitable in some applications include a gasket, a bead of adhesive material, double sided foam tape, hook and loop fastener strips, and the like. 
   A first edge flange  528  and an intermediate portion  532  of second shell piece  520  are visible in FIG.  9 . Second shell piece  520  of helmet  500  may comprise a first edge flange, a second edge flange, and an intermediate portion  532  extending between the first edge flange and the second edge flange. In the embodiment of  FIG. 9 , intermediate portion  532  of second shell piece  520  has a curved shape in lateral cross-section. 
   In the embodiment of  FIG. 9 , trough  560  includes a shoulder  598  that is dimensioned such that first edge flange  528  of the second shell piece  520  rests on shoulder  598  of trough  560  while second shell piece  520  is attached to first shell piece  502 . In  FIG. 9 , it may be appreciated that shoulder  598  of trough  560  is located at a depth corresponding to a thickness of first edge flange  528  of second shell piece  520 . Accordingly, an outer surface  537  of first edge flange  528  is substantially flush with an outer surface  536  of first shell piece  502  in the embodiment of FIG.  9 . 
   In certain advantageous embodiments of the present invention, interface  522  has a pre-selected separation force. When this is the case, first shell piece  502  and second shell piece  520  will separate if the force applied across interface  522  exceeds a pre-selected value. In some embodiments, the pre-selected separation force may be selected to reduce the likelihood that a vehicle rider will be dislodged from a vehicle by a force applied to second shell piece  520  during riding. Embodiments of the present invention are possible in which the material forming strip  544  is selected such that an adhesive joint is broken if the force applied across interface  522  exceeds the pre-selected level. Embodiments of the present invention are also possible in which strip  544  breaks if the force applied across interface  522  exceeds a pre-selected level. 
     FIG. 10  is a partial cross sectional view of a helmet  600  in accordance with an exemplary embodiment of the present invention. Helmet  600  of  FIG. 10  includes a second shell piece  620  that is attached to a first shell piece  602  at an interface  622 . In the embodiment of  FIG. 10 , interface  622  comprises a fastener  624 . In the embodiment of  FIG. 10 , fastener  624  comprises a shaft  690 . 
   In the embodiment of  FIG. 10 , second shell piece  620  is disposed within a trough  660  defined by first shell piece  602  so that second shell piece  620  and first shell piece  602  define a flow channel  638 . In the embodiment of  FIG. 10 , trough  660  includes a shoulder  698  that is dimensioned such that a first edge flange  628  of the second shell piece  620  rests on shoulder  698  of trough  660  while second shell piece  620  is attached to first shell piece  602 . In  FIG. 10 , it may be appreciated that shoulder  698  of trough  660  is located at a depth corresponding to a thickness of first edge flange  628  of second shell piece  620 . Accordingly, an outer surface  637  of first edge flange  628  is substantially flush with an outer surface  636  of first shell piece  602  in the embodiment of FIG.  10 . 
   In certain advantageous embodiments of the present invention, interface  622  has a pre-selected separation force. When this is the case, first shell piece  602  and second shell piece  620  will separate if the force applied across interface  622  exceeds a pre-selected value. In some embodiments, the pre-selected separation force may be selected to reduce the likelihood that a vehicle rider will be dislodged from a vehicle by a force applied to second shell piece  620  during riding. Embodiments of the present invention are possible in which each fastener  624  may be adapted to release at a pre-selected force. Embodiments of the present invention are also possible in which shaft  690  of fastener  624  is adapted to break when a pre-selected breaking force is applied thereto. For example, the material forming fastener  624  and the diameter of shaft  690  may be selected so that shaft  690  breaks when the pre-selected breaking force is applied to the shaft. The pre-selected breaking force may be, for example, an axial force. The pre-selected breaking force may also be, for example, a shear force. 
   While the invention has been described in conjunction with specific embodiments thereof, it is evident that other alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the invention.