Patent Publication Number: US-9420842-B2

Title: Protective helmet

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Ser. No. 13/721,186 filed Dec. 20, 2015, now U.S. Pat. No. 9,113,672, which claims priority to and the benefit of U.S. Provisional Application No. 61/631,549 filed on Jan. 6, 2012. The entire disclosure of each of the above applications is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates generally to a protective helmet and, more particularly to a protective helmet comprised of an outer shell and a controlled air dissipation assembly that can be installed within the outer shell. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Protective helmets are used in a variety of sporting and racing activities, in addition to military duty, to assist in protecting the wearer&#39;s head from impact related injuries. Such protective helmets are most commonly used in sporting activities such as, for example without limitation, football, hockey, lacrosse, cycling and baseball. Likewise, protective helmets are used in both on-road and off-road racing activities such as, for example without limitation, stock car and open-wheel racing, drag-racing, motorcycle racing, moto-cross racing and go-cart racing. 
     A primary function of protective helmets is to protect the wearer from head injuries associated with high impact forces that may be sustained during the above-noted sporting and racing activities. Conventional protective helmets consist of a rigid outer shell and an impact damping or cushioning assembly disposed between the outer shell and the wearer&#39;s head. Many known damping assemblies utilize a compressible material to absorb and dissipate the impact force. Typically, such compressible materials have included pressurized air, viscous gel-like mediums, foam or a combination thereof. 
     While such conventional protective helmets perform satisfactorily for their intended purpose, recent awareness regarding the detrimental long-term effects that head impacts may have on athletes, particularly football and hockey players, has led to a need for continued development of improved impact damping technology. Accordingly, there is a recognized need in the art to design and develop alternative technologies that advance the protection afforded to those wearing a protective helmet. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In accordance with one aspect of the present disclosure, a protective helmet is disclosed which incorporates an energy dissipation system for dissipating the energy associated with an impact force applied to the protective helmet and embodying a unique and non-obvious dual-stage air dissipation technology. 
     In accordance with a related aspect of the present disclosure, the protective helmet includes an outer shell and a controlled air dissipation (“CAD”) assembly installed within the outer shell and which utilizes the dual-stage air dissipation technology. 
     In accordance with these and other aspect, features and objects, the present disclosure relates to a protective helmet having the CAD assembly removeably installed in the interior cavity of the outer shell. The CAD assembly includes a primary or outer bellows unit, a secondary or inner bellows unit, and an inner shell liner disposed between the primary and secondary bellows units. The primary bellows unit is secured in a sealed air-tight manner to an outer surface of the inner shell liner. The primary bellows unit includes a plurality of primary bellows chambers which are interconnected by primary air bridge channels to facilitate the transfer of air between adjacent primary bellows chambers. The primary bellows chambers are defined between the outer surface of the inner shell liner and a series of interconnected first stage air-filled pad sections. The first stage pad sections are adapted to engage an inner surface of the outer shell. A primary air charge hole extends through each of the first stage pad sections to permit ambient air to be in fluid communication with the corresponding primary bellows chamber. The secondary bellows unit is secured in a sealed air-tight manner to an inner surface of the inner shell liner. The secondary bellows unit includes a plurality of secondary bellows chambers which are interconnected by secondary air bridge channels to facilitate the transfer of air between adjacent secondary bellow chambers. The secondary bellow chambers are defined between the inner surface of the inner shell liner and a series of interconnected second stage air-filled pad sections. The second stage pad sections are adapted to engage the head of a person wearing the protective helmet. A secondary air charge hole extends through each of the second stage pad sections to permit ambient air to be in fluid communication with the corresponding secondary bellows chamber. Air transfer holes extending through the inner shell liner facilitate the transfer of air between corresponding pairs of primary and secondary bellow chambers. 
     In accordance with one exemplary embodiment of the CAD assembly, the primary bellows chambers and the secondary bellows chambers associated with the primary and secondary bellows units are configured in a substantially mirror-image arrangement such that each primary bellows chamber is in fluid communication with a similarly configured secondary bellows chamber via the air transfer hole formed through the inner shell liner. 
     In accordance with another exemplary embodiment of the CAD assembly, the inner shell liner includes front and rear mounting flanges for releasably mounting the CAD assembly to the outer shell of the protective helmet. In addition, baffle projections are formed within the primary and secondary bellows chambers to facilitate directional flow of air therein during an air transfer event caused by resilient deflection of the first stage pad sections and/or the second stage pad sections in response to an impact force being imparted on the outer shell of the protective helmet. 
     In accordance with another exemplary embodiment of the CAD system, the primary bellows unit includes a plurality of interconnected primary bellows chambers configured and arranged to define at least one primary crown bellows chamber, at least one primary front bellows chamber, at least one primary rear bellows chamber, a plurality of primary side bellows chambers, and a pair of primary ear bellows chambers. The at least one primary crown bellows chamber defines a first stage crown pad section that is generally aligned with a crown region of the outer shell. The at least one primary front bellows chamber defines a first stage front pad section that is generally aligned with a frontal region of the outer shell. The at least one primary rear bellows chamber defines a first stage rear pad section that is generally aligned with an aft region of the outer shell. The plurality of primary side bellows chambers define a plurality of first stage side pad sections disposed below the first stage crown pad and between the first stage front and rear pad sections and which are generally aligned with side regions of the outer shell. Finally, the pair of primary ear bellows chambers define a pair of first stage ear pad sections disposed below the first stage side pad sections and which are generally aligned with an ear/jaw region of the outer shell. 
     In accordance with a related exemplary embodiment of the CAD assembly, the secondary bellows unit includes a plurality of interconnected secondary bellows chambers configured and arranged to define at least one secondary crown bellows chamber, at least one secondary front bellows chamber, at least one secondary rear bellows chamber, a plurality of secondary side bellows chambers, and a pair of secondary ear bellows chambers. The at least one secondary crown bellows chamber defines a second stage crown pad section that is generally aligned with a crown region of the helmet wearer&#39;s head. The at least one secondary front bellows chamber defines a second stage front pad section that is generally aligned with a front region of the helmet wearer&#39;s head. The at least one secondary rear bellows chamber defines a second stage rear pad section that is generally aligned with a rear region of the helmet wearer&#39;s head. The plurality of secondary side bellows chambers define a plurality of second stage side pad sections disposed below the second stage crown pad section and between the second stage front and rear pad sections and which are generally aligned with side regions of the helmet wearer&#39;s head. Finally, the pair of secondary ear bellows chambers define a pair of second stage ear pad sections disposed below the second stage side pad sections and which are generally aligned with an ear/jaw region of the helmet wearer&#39;s head. 
     In accordance with a still further related embodiment of the CAD assembly, the first stage pad sections associated with the primary bellows unit extend outwardly from the outer surface of the inner shell liner while the second stage pad sections associated with the secondary bellows unit extend inwardly from the inner surface of the inner shell liner. Air transfer holes extending through the inner shell liner facilitate the transfer of air between aligned sets of the bellows chambers associated with corresponding first stage pad sections and second stage pad sections. 
     In accordance with yet another exemplary embodiment of the CAD assembly, the first stage pad sections provide an initial cushion of air and function to dampen an impact applied to the outer shell by delaying the impact force from being transferred to the head of the wearer of the protective helmet. Specifically, collapse of the first stage pad sections upon the impact acts to forcibly transfer air between the interconnected primary bellows chambers so as to spread the impact force and dissipate the magnitude of the impact force transferred from the outer shell to the primary bellows unit. In addition, air is forcibly transferred through the air transfer holes into the secondary bellows chambers of the corresponding second stage pad sections. Subsequent collapse of the second stage pad sections upon engagement with the wearer&#39;s head acts to forcibly transfer air between the interconnected secondary bellows chambers. Air is then transferred from the secondary bellows chambers through the air charge holes and back into the primary bellows chambers, thereby continuously filling and refilling interconnected pairs of primary and secondary bellows chambers so as to disperse the impact forces around and out of the protective helmet. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is an isometric view of a protective helmet configured and constructed in accordance with the teachings of the present disclosure to include a rigid outer shell and a controlled air dissipation (“CAD”) assembly attached within the outer shell; 
         FIG. 2  is a sectional view of the protective helmet shown in  FIG. 1  and which illustrates the mounting structure utilized to removeably attach the CAD assembly within the rigid outer shell; 
         FIG. 3  is an isometric view of the CAD assembly removed from the outer shell of the protective helmet and showing the CAD assembly to include a primary bellows unit, a secondary bellows unit, and an inner shell liner disposed between the primary and secondary bellows units; 
         FIG. 4  is a frontal isometric view of the CAD assembly, with portions of the mounting structure associated with the inner shell liner removed for additional clarity; 
         FIG. 5  is a sectional view taken generally along line A-A of  FIG. 4 ; 
         FIG. 6  is generally similar to  FIG. 4  except that the secondary bellows unit has been removed for purposes of additional clarity regarding various features of the CAD assembly; 
         FIG. 7  is a side isometric view of the CAD assembly shown in  FIG. 6 ; 
         FIG. 8  is a rear isometric view of the CAD assembly shown in  FIGS. 6 and 7 ; 
         FIG. 9  is a top isometric view of the CAD assembly shown in  FIGS. 6 through 8 ; 
         FIGS. 10A and 10B  are vertical sectional views of the primary bellows unit associated with the CAD assembly of the present disclosure; 
         FIGS. 11A and 11B  are views of the inner shell liner associated with the CAD assembly of the present disclosure; 
         FIG. 12  is an isometric view of the secondary bellows unit associated with the CAD assembly of the present disclosure; 
         FIG. 13  is a side isometric view of the secondary bellows unit installed in the inner shell liner, which is shown in phantom for improved clarity of the illustration; 
         FIG. 14  is a rear isometric view of the secondary bellows unit and inner shell liner shown in  FIG. 13 ; 
         FIG. 15  is a sectional view taken through a portion of the secondary bellows unit; 
         FIG. 16  is a sectional view taken through a portion of the CAD assembly; and 
         FIGS. 17A and 17B  graphically illustrates action of the CAD assembly in response to a rotational acceleration condition. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments are solely provided so that this disclosure will be thorough and fully convey the scope of the present disclosure to those who are skilled in the art. To this end, numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The present disclosure is generally directed to a protective helmet incorporating a novel and unobvious air transfer and metering technology, hereinafter referred to as “dual-stage air dissipation technology”, for use in absorbing and/or transferring impact loads imparted onto the helmet&#39;s outer shell prior to transmission of such impact loads to the head of the helmet wearer. While a specific type of protective helmet is shown in the drawings, particularly a football helmet, those skilled in the art will appreciate and acknowledge that the dual-stage air dissipation technology of the present disclosure can be readily incorporated into any other types of protective helmets used by a wearer to provide head protection. To this end, it is contemplated that the teachings of the present disclosure are applicable to protective helmets used for other activities including, but not limited to, baseball, hockey, lacrosse, cycling, motor racing (i.e., on-road and off-road), moto-cross and motorcycles as well as for use in military applications. 
     Referring primarily to  FIG. 1 , a protective helmet  10  constructed in accordance with the teachings of the present disclosure is shown to generally include an outer shell  12  and a controlled air dissipation assembly, hereafter referred to as CAD assembly  14 . Outer shell  12  is an otherwise conventional helmet configuration of the type commonly used as part of a football helmet and is shown to include ear holes  16  and a plurality of vent holes  18 . Those skilled in the art will recognize that a face mask (not shown) can be secured to an open front portion of outer shell  12  in a known manner. Additionally, outer shell  12  can include snaps (not shown) to facilitate attachment of a chin strap thereto. While not specifically limited thereto, outer shell can be fabricated from a suitable rigid material, such as polycarbonate or ABS. As will be detailed, CAD assembly  14  is removeably secured within an inner cavity of outer shell  12  in proximity to an inner wall surface  20  thereof. 
     Referring now primarily to  FIGS. 2 and 3 , CAD assembly  14  is shown generally as a three component assembly comprised of an outer or primary bellows unit  100 , an inner or secondary bellows unit  200 , and an inner shell liner  300  that is disposed between primary bellows unit  100  and secondary bellows unit  200 . Inner shell liner  300  is shown to include a front U-shaped mounting flange  302  and a rear U-shaped mounting flange  304 , each having a corresponding mounting groove  302 A,  304 A that is sized to accept and retain front and rear portions of outer shell  12  therein. While not shown, fasteners can be used to secure mounting flanges  302  and  304  to outer shell  12 . Based on this exemplary construction, CAD assembly  14  can be easily installed or removed from the internal cavity of outer shell  12  using the mounting structure associated with inner shell liner  300 . 
     As will be detailed hereinafter with much greater specificity, primary bellows unit  100  includes a plurality of first stage pad sections each defining a primary bellows chamber that is in fluid communication with at least one other adjacent primary bellows chamber and which are each in communication with ambient air via primary air charge holes. An outer surface of the first stage pad sections is configured to engage, or be located in close proximity to, inner surface  20  of outer shell  12 . Likewise, secondary bellows unit  200  includes a plurality of second stage pad sections each defining a secondary bellows chamber that is in fluid communication with at least one other adjacent secondary bellows chamber and which are each in communication with ambient air via secondary air charge holes. The second stage pad sections are configured to engage, or be in close proximity to, the head of a person wearing protective helmet  10 . Inner shell liner  300  includes a plurality of air transfer holes that facilitate the transfer of air between corresponding sets of aligned primary and second bellows chambers. Accordingly, CAD assembly  14  is configured to define a dual stage air dissipation system which, upon an impact force being applied to outer shell  12 , facilitates: A) the transfer of air between adjacent primary bellows chambers; B) the transfer of air between adjacent secondary bellows; and C) the transfer of air between aligned sets of primary and secondary bellows chambers. 
     In accordance with the dual stage air dissipation system, the above-noted transfer of ambient air is controlled and regulated to dissipate the impact forces applied to helmet  10 . Upon the head of the helmet wearer encountering an impact, one or more of the first stage pad sections and, subsequently, one or more of the second stage pad sections are resiliently deflected to cause a regulated and controlled transfer of air between adjacent bellows chambers. This regulated air transfer is operable to react against the forces associated with the impact and create an air-cushioned energy dissipation process. This energy dissipation process is operable to spread the impact forces to a much larger area, thereby delaying the time between actual impact and the subsequent release of the energy created and ultimately transferred to the wearer&#39;s head. 
     Primary bellows unit  100  of CAD assembly  14  is generally shown to include a plurality of first stage pad sections extending outwardly from a primary base section  102  that, in turn, is secured in an air-tight manner to an outer surface  306  of inner shell liner  300 . Since the first stage pad sections are normally filled with non-pressurized ambient air, they are configured to deflect in response to an impact load applied to outer shell  12 . It is contemplated that primary bellows unit  100  can be a one-piece molded component formed from a suitably semi-rigid, yet resilient material. One suitable material may include TPU (Thermal Plastic Urethane), TPE (Thermal Polyester Elastollen) or a blended Thermal Elastomer. 
     The first stage pad sections can be grouped into distinct sections associated with base section  102 . Specifically, the first stage pad sections may include at least one crown pad section  104 , at least one front pad section  106 , a plurality of peripheral side pad sections  108 A- 108 H, a pair of ear pad sections  110 A,  110 B, and a plurality of rear pad sections  112 A- 112 D.  FIG. 3  illustrates the first stage pad sections mentioned above extending outwardly from primary base section  102 .  FIGS. 4 and 6 through 9  illustrate these first stage pad sections in a generally translucent manner to better define and show one or more internal baffle projections that are formed in each of the corresponding primary bellows chambers. The arrangement and function of such internal baffle projections will be described hereinafter in greater detail. 
     With primary reference to  FIGS. 4 through 10 , the specific construction and features associated with primary bellows unit  100  will now be described in more detail. Upon assembly of CAD assembly  14  into outer shell  12 , crown pad section  104  will be located at a crown region of outer shell  12  and is generally configured to be arcuate and define a generally cylindrical primary crown bellows chamber  114 . An inner surface of crown pad section  104  within primary crown bellows chamber  114  is shown to include a cross-shaped baffle projection  115  extending downwardly therefrom and which projects toward outer surface  306  of inner shell liner  300 . Cross-shaped baffle projection  115  generally segregates primary crown bellows chamber  114  into quadrants and facilitates a radially outward and centrifugal air flow pattern therein. A pair of primary air charge holes  116  extend through crown pad section  104  to permit ambient air to communicate with front and back portions of primary crown bellows chamber  114 . 
     A first primary air bridge channel  118  is shown to interconnect primary crown bellows chamber  114  for fluid communication with a primary side bellows chamber  120  associated with side pad section  108 D while a second primary air bridge channel  122  is shown to interconnect primary crown bellows chamber  114  for fluid communication with a primary side bellows chamber  124  associated with side pad section  108 H. Each of the primary air bridge channels described hereinafter is configured as a tubular passage extending outwardly from base section  102  between a pair of primary bellows chambers. 
     Upon installation of CAD assembly  14  within outer shell  12 , front pad section  106  of primary bellows unit  100  is oriented to be located at a forward region of outer shell  12  and defines a primary front bellows chamber  126 . A plurality of elongated baffle projections  127  extend downwardly into primary front bellows chamber  126  to form a labyrinth type air flow pattern therein ( FIG. 4 ). A third primary air bridge channel  128  is shown to provide fluid communication between primary front bellows chamber  126  and a primary side bellows chamber  130  associated with side pad section  108 A. Likewise a fourth primary air bridge channel  132  provides fluid communication between primary front bellows chamber  126  and primary side bellows chamber  124  associated with side pad section  108 H. A primary air charge hole  134  extends through front pad section  106  to permit ambient air to communicate with primary front bellows chamber  126 . 
     As noted, side pad section  108 A defines primary side bellows chamber  130 . A pair of elongated baffle projections  135  extend downwardly into primary side bellows chamber  130  to establish a labyrinth type air flow pattern therein. A primary air charge hole  136  extends through side pad section  108 A to permit ambient air to communicate with primary side bellows chamber  130 . A fifth primary air bridge channel  138  provides fluid communication between primary side bellows chamber  130  of side pad section  108 A and a primary side bellows chamber  140  associated with side pad section  108 B. A pair of elongated baffle projections  141  extend downwardly into primary side bellows chamber  140  to establish a labyrinth type air flow pattern therein. A primary air charge hole  142  extends through side pad section  108 B to permit ambient air to communicate with primary side bellows chamber  140 . A sixth primary air bridge channel  144  provides fluid communication between primary side bellows chamber  140  of side pad section  108 B and a primary side bellows chamber  146  associated with side pad section  108 C. A pair of elongated baffle projections  147  extend downwardly into primary side bellows chamber  146  to establish a labyrinth type air flow pattern therein. A primary air charge hole  148  extend through side pad section  108 C to permit ambient air to communicate with primary side bellows chamber  146 . 
     A seventh primary air bridge channel  150  provides fluid communication between primary side bellows chamber  146  of side pad section  108 C and primary side bellows chamber  120  associated with side pad section  108 D. A pair of elongated baffle projections  153  extend downwardly into primary side bellows chamber  120  to establish a labyrinth type air flow pattern therein. A primary air charge hole  154  extends through side pad section  108 D to permit ambient air to communicate with primary side bellows chamber  120 . 
     As previously disclosed, primary side bellows chamber  124  of side pad section  108 H is in fluid communication with primary crown bellows chamber  114  of crown pad section  104  via second primary air bridge channel  122  and is also in fluid communication with primary front bellows chamber  126  of front pad section  106  via fourth primary air bridge channel  132 . Primary side bellows chamber  124  of side pad section  108 H is also in fluid communication with a primary side bellows chamber  156  associated with side pad section  108 G via an eighth primary air bridge channel  158 . A pair of elongated baffle projections  159  extend downwardly into primary side bellows chamber  156  so as to establish a labyrinth type air flow pattern therein. A primary air charge hole  160  extends through side pad section  108 G to permit ambient air to communicate with primary side bellows chamber  156 . 
     A ninth primary air bridge channel  162  provides fluid communication between primary side bellows chamber  156  of side pad section  108 G and a primary side bellows chamber  164  associated with side pad section  108 F. A pair of elongated baffle projections  165  extend into primary side bellows chamber  164  and establish a labyrinth type air flow pattern therein. A primary air charge hole  166  extends through side pad section  108 F to permit ambient air to communicate with side bellows chamber  164 . A tenth primary air bridge channel  168  provides fluid communication between primary side bellows chamber  164  of side pad sections  108 F and a primary side bellows chamber  170  associated with side pad section  108 E. Baffle projections  169  extend into side bellows chamber  170  to establish a labyrinth type air flow pattern therein. A primary air charge hole  172  extends through side pad sections  108 E to permit ambient air to communicate with primary side bellows chamber  170 . 
     Right ear pad section  110 A of primary bellows unit  100  defines a primary ear bellows chamber  174  having one or more elongated baffle projections  175  for establishing a labyrinth type air flow pattern therein. Primary ear bellows chamber  174  is in fluid communication with primary side bellows chamber  140  of side pad section  108 B via an eleventh primary air bridge channel  176 . A primary air charge hole  177  extends through ear pad section  110 A to permit ambient air to communicate with primary ear bellows chamber  174 . Similarly, left ear pad section  110 B of primary bellows unit  100  defines a primary ear bellows chamber  178  having one or more elongated baffle projections  179  for establishing a labyrinth type air flow pattern therein. Primary ear bellows chamber  178  is in fluid communication with side bellows chamber  156  of side pad section  108 G via a twelfth primary air bridge channel  180 . A primary air charge hole  181  extends through ear pad section  110 B to permit ambient air to communicate with primary ear bellows chamber  178 . 
     Upon assembly of CAD assembly  14  into outer shell  12 , back pad sections  112 A- 112 D of primary bellows unit  100  are aligned and position adjacent to a back region of inner surface  20  of outer shell  12 . Upper back pad sections  112 A and  112 C are located above lower back pad sections  112 B and  112 D, respectively. Upper back pad section  112 A defines a first primary upper back bellows chamber  182  that is in fluid communication with side bellows chamber  120  of side pad section  108 D via a thirteenth primary air bridge channel  184 . A pair of transversely oriented elongated baffle projections  185  extend into first primary upper back bellows chamber  182  and are arranged to establish a non-laminar air flow pattern therein. A primary air charge hole  186  extends through upper back pad section  112 A to permit ambient air to communicate with first primary upper back bellows chamber  182 . First primary upper back bellows chamber  182  of upper back pad section  112 A is in fluid communication with a first primary lower back bellows chamber  188  associated with lower back pad section  112 B via a fourteenth air bridge channel  190 . A pair of transversely oriented elongated baffle projections  191  extend into first primary lower back bellows chamber  188  and are arranged to establish a non-laminar air flow pattern therein. A primary air charge hole  192  extends through lower back pad section  112 B to permit ambient air to communicate with first primary lower back bellows chamber  188 . 
     Similarly, upper back pad section  112 C defines a second primary upper back bellows chamber  194  that is in fluid communication with primary side bellows chamber  170  of side pad section  108 E via a fifteenth air bridge channel  195 . A pair of transversely oriented elongated baffle projections  193  extend into second primary upper back bellows chamber  194  and are arranged to establish a non-laminar flow pattern therein. A primary air charge hole  196  extends through upper back pad section  112 C to permit ambient air to communicate with second primary upper back bellows chamber  194 . Second primary upper back bellows chamber  194  of upper back pad section  112 C is in fluid communication with a second primary lower back bellows chamber  198  associated with lower back pad section  112 D via a sixteenth air bridge channel  197 . A pair of transversely oriented elongated baffle projections  199  are arranged to establish a non-laminar air flow pattern within second primary lower back bellows chamber  198 . A primary air charge hole  187  extends through lower back pad section  112 D to permit ambient air to communicate with second primary lower back bellows chamber  198 . 
     As described above, primary bellows unit  100  of CAD assembly  14  includes a plurality of primary bellows chambers that are each in fluid communication with at least one other primary bellows chamber via a primary air bridge channel. When base section  102  is attached to outer surface  302  of inner shell liner  300 , the primary bellows chambers and the primary air bridge channel cooperate to define a continuous primary air flow circuit. While each of the primary air charge holes is noted to facilitate transfer of ambient air into and out of each of the primary bellows chamber, they also function to permit the release of moisture or condensation therefrom. It will be noted that a plurality of cut-outs  103  are formed in base section  102  of primary bellows unit  100  between first stage crown pad section  104  and first stage side pad sections  108 A- 108 H to provide mass reduction and facilitate improved ventilation. These cut-outs  103  are matched in size and configuration to similar cut-outs  303  formed in inner shell liner  300  and cut-out  203  formed in secondary bellows unit  200 . Additional cut-outs may be provided between the ear pad sections and the lower back pad sections if desired. 
     Secondary bellows unit  200  of CAD assembly  14  is generally shown to include a plurality of second stage pad sections extending from a secondary base section  202  that, in turn, is secured in an air-tight manner to an inner surface  308  of inner shell liner  300 . Since the second stage pad sections are filled with non-pressurized ambient air, they are configured to deflect in response to an impact load applied by the head of the helmet wearer. It is contemplated that secondary bellows unit  200  can be a one-piece molded component formed from a suitably semi-rigid, yet resilient material. One suitable material may include TPE. 
     The second stage pad sections can be grouped into distinct sections associated with base section  202 . Specifically, the second stage pad sections may include at least one crown pad section  204 , at least one front pad section  206 , a plurality of peripheral side pad sections  208 A- 208 H, a pair of ear pad sections  210 A,  210 B, and a plurality of rear pad sections  212 A- 212 D.  FIGS. 2 and 3  illustrate the second stage pad sections mentioned above extending inwardly from secondary base section  202 .  FIGS. 12 through 16  illustrate these second stage pad sections, some shown in a generally translucent manner, to better define and show one or more internal baffle projections that are formed in each of the corresponding secondary bellows chambers. In a preferred arrangement, the second pad sections are mirror-image versions of the first pad sections so as to be symmetrical relative to a plane through inner shell liner  300 . 
     Upon assembly of CAD assembly  14  into outer shell  12 , second stage crown pad section  204  will be located at a crown region of the helmet wearer&#39;s head and is generally configured to be arcuate and define a generally cylindrical secondary crown bellows chamber  214 . Secondary crown bellows chamber  214  is shown to include cross-shaped baffle projections  215  extending upwardly therefrom and which projects toward inner surface  308  of inner shell liner  300 . Cross-shaped baffle  215  generally segregates secondary crown bellows chamber  214  into quadrants and facilitates a radially outward and centrifugal air flow pattern therein. A pair of secondary air charge holes  216  extend through crown pad section  204  to permit ambient air to communicate with secondary crown bellows chamber  214 . 
     A first secondary air bridge channel  218  is shown to interconnect secondary crown bellows chamber  214  for fluid communication with a secondary side bellows chamber  220  associated with side pad section  208 D while a second primary air bridge channel  222  is shown to interconnect secondary crown bellows chamber  214  for fluid communication with a secondary side bellows chamber  224  associated with side pad section  208 H. Each of the secondary air bridge channels described hereinafter is configured as a tubular air flow passage extending from base section  202 . 
     Upon installation of CAD assembly  14  within outer shell  12 , second stage front pad section  206  of secondary bellows unit  200  is oriented to be located at a forward region of helmet  10  and defines a secondary front bellows chamber  226 . A plurality of elongated baffle projections  227  extend into secondary front bellows chamber  226  to form a labyrinth type air flow pattern therein. A third secondary air bridge channel  228  is shown to provide fluid communication between secondary front bellows chamber  226  of front pad section  206  and a secondary side bellows chamber  230  associated with side pad section  208 A. Likewise a fourth secondary air bridge channel  232  provides fluid communication between secondary front bellows chamber  226  of front pad section  206  and secondary side bellows chamber  224  of side pad section  208 H. A secondary air charge hole  234  extends through front pad section  206  to permit ambient air to communicate with secondary front bellows chamber  226 . 
     As noted, side pad section  208 A defines secondary side bellows chamber  230 . A pair of elongated baffle projections  235  extend into secondary side bellows chamber  230  to establish a labyrinth type air flow pattern therein. A secondary air charge hole  236  extends through side pad section  208 A to permit ambient air to communicate with secondary side bellows chamber  230 . A fifth secondary air bridge channel  238  provides fluid communication between secondary side bellows chamber  230  of side pad section  208 A and a secondary side bellows chamber  240  associated with side pad section  208 B. A pair of elongated baffle projections  241  extend into secondary side bellows chamber  240  to establish a labyrinth type air flow pattern therein. A secondary air charge hole  242  extends through side pad section  208 B to permit ambient air to communicate with secondary side bellows chamber  240 . A sixth secondary air bridge channel  244  provides fluid communication between secondary side bellows chamber  240  of side pad section  208 B and a secondary side bellows chamber  246  associated with side pad section  208 C. A pair of elongated baffle projections  247  extend into secondary side bellows chamber  246  to establish a labyrinth type air flow pattern therein. A secondary air charge hole  248  extends through side pad section  208 C to permit ambient air to communicate with secondary side bellows chamber  246 . 
     A seventh secondary air bridge channel  250  provides fluid communication between secondary side bellows chamber  246  of side pad section  208 C and secondary side bellows chamber  220  associated with side pad section  208 D. A pair of elongated baffle projections  253  extend into secondary side bellows chamber  220  to establish a labyrinth type air flow pattern therein. A secondary air charge hole  254  extends through side pad section  208 D to permit ambient air to communicate with secondary side bellows chamber  220 . 
     As previously disclosed, secondary side bellows chamber  224  of side pad section  208 H is in fluid communication with secondary crown bellows chamber  214  of crown pad section  204  via second secondary air bridge channel  222  and is also in fluid communication with secondary front bellows chamber  226  of front pad section  206  via fourth secondary air bridge channel  232 . Secondary side bellows chamber  224  of side pad section  208 H is also in fluid communication with a secondary side bellows chamber  256  associated with side pad section  208 G via an eighth secondary air bridge channel  258 . A pair of elongated baffle projections  259  extend into secondary side bellows chamber  256  so as to establish a labyrinth type air flow pattern therein. A secondary air charge hole  260  extends through side pad section  208 G to permit ambient air to communicate with secondary side bellows chamber  256 . 
     A ninth secondary air bridge channel  262  provides fluid communication between secondary side bellows chamber  256  of side pad section  208 G and a secondary side bellows chamber  264  associated with side pad section  208 F. A pair of elongated baffle projections  265  extend into secondary side bellows chamber  264  and establish a labyrinth type air flow pattern therein. A secondary air charge hole  266  extends through side pad section  108 F to permit ambient air to communicate with secondary side bellows chamber  264 . A tenth primary air bridge channel  268  provides fluid communication between secondary side bellows chamber  264  of side pad section  208 F and a secondary side bellows chamber  270  associated with side pad section  208 E. Baffle projections  269  extend into secondary side bellows chamber  270  to establish a labyrinth type air flow pattern therein. A secondary air charge hole  272  extends through side pad section  208 E to permit ambient air to communicate with secondary side bellows chamber  270 . 
     Right ear pad section  210 A of secondary bellows unit  200  defines a secondary ear bellows chamber  274  having one or more elongated baffle projections  275  for establishing a labyrinth type air flow pattern therein. Secondary ear bellows chamber  274  of ear pad section  210 A is in fluid communication with secondary side bellows chamber  240  of side pad section  208 B via an eleventh air bridge channel  276 . A secondary air charge hole  272  extends through ear pad section  210 A to permit ambient air to communicate with secondary ear bellows chamber  274 . Similarly, left ear pad section  210 B of secondary bellows unit  200  defines a secondary ear bellows chamber  278  having one or more elongated baffle projections  279  for establishing a labyrinth type air flow pattern therein. Secondary ear bellows chamber  278  of left ear pad section  210 B is in fluid communication with secondary side bellows chamber  256  of side pad section  208 G via a twelfth air bridge channel  280 . A secondary air charge hole  281  extends through ear pad section  210 B to permit ambient air to communicate with secondary ear bellows chamber  178 . 
     Upon assembly of CAD assembly  14  into outer shell  12 , back pad sections  212 A- 212 D of secondary bellows unit  200  are aligned and positioned adjacent to a back region of helmet  10 . Upper back pad sections  212 A and  212 C are located above lower back pad sections  212 B and  212 D, respectively. Upper back pad section  212 A defines a first secondary upper back bellows chamber  282  that is in fluid communication with secondary side bellows chamber  220  of side pad section  208 D via a thirteenth air bridge channel  284 . A pair of transversely oriented elongated baffle projections  285  extend into first secondary upper back bellows chamber  282  and are arranged to establish a non-laminar air flow pattern therein. A secondary air charge hole  286  extends through upper back pad section  212 A to permit ambient air to communicate with first secondary upper back bellows chamber  282 . First secondary upper back bellows chamber  282  of upper back pad section  212 A is in fluid communication with a first secondary lower back bellows chamber  288  associated with back pad section  212 B via a fourteenth air bridge channel  290 . A pair of transversely oriented elongated baffle projections  291  extend into first secondary lower back bellows chamber  288  and are arranged to establish a non-laminar air flow pattern therein. A secondary air charge hole  292  extends through lower back pad section  212 B to permit ambient air to communicate with first secondary lower back bellows chamber  288 . 
     Similarly, upper back pad section  212 C defines a second secondary upper back bellows chamber  294  that is in fluid communication with secondary side bellows chamber  270  of side pad section  208 E via a fifteenth air bridge channel  295 . A pair of transversely oriented elongated baffle projections  293  extend into second secondary upper back bellows chamber  294  and are arranged to establish a non-laminar flow pattern therein. A secondary air charge hole  296  extends through upper back pad section  212 C to permit ambient air to communicate with second secondary upper back bellows chamber  294 . Second secondary upper back bellows chamber  294  of upper back pad section  212 C is in fluid communication with a second secondary lower back bellows chamber  298  associated with lower back pad section  212 D via a sixteenth air bridge channel  297 . A pair of transversely oriented elongated baffle projections  299  are arranged to establish a non-laminar air flow pattern within second secondary lower back bellows chamber  298 . A secondary air charge hole  287  extends through lower back pad section  212 D to permit ambient air to communicate with second secondary lower back bellows chamber  298 . 
     As described above, secondary bellows unit  200  of CAD assembly  14  includes a plurality of secondary bellows chambers that are each in fluid communication with at least one other secondary bellows chamber via a secondary air bridge channel. When base section  202  is attached to inner surface  308  of inner shell liner  300 , the secondary bellows chamber and the secondary air bridge channels define a continuous secondary air flow circuit. While each of the secondary air charge holes is noted to facilitate transfer of ambient air into and out of each of the secondary bellows chambers, they also function to permit the release of moisture or condensation therefrom. 
     As noted, each of the primary bellows chambers is in fluid communication with a corresponding one of the secondary bellows chambers via an air transfer hole extending through the inner shell liner.  FIGS. 6, 7, 11, 13 and 14  illustrate many of these air transfer holes. Air transfer holes  310  provide fluid communication between the aligned primary crown bellows chamber and the secondary crown bellows chamber. Similarly, air transfer holes  312  provide fluid communication between aligned sets of the primary side bellows chambers and secondary side bellows chambers. Air transfer holes  314 A,  314 B provide fluid communication between the upper and lower sets of primary back and secondary back bellows chambers, respectively. Finally, air transfer holes  316  provide fluid communication between the aligned primary ear bellows chambers and secondary ear bellows chambers. Inner shell liner  300  is preferably made of a material having sufficient rigidity to support primary bellows unit  100  and secondary bellows unit  200 , and yet have a hardness less than outer shell  12 . One suitable material for inner shell  300  is a more dense or stiffer blend of the same material used for the bellows units (i.e., TPE or TPU). Most importantly, inner shell  300  must be more rigid than the stage one and stage two pad sections so as to permit a plurality of pad sections to compress at a time and spread the energy over a larger area. 
     Referring to  FIG. 5 , baffle projections  127  associated with first stage front pad section  106  and baffle projections  227  associate with second stage front pad section  206  are shown to have a generally common “thickness” dimension across their entire height and length. While such common or “straight” baffle projections are acceptable, it has been determined that use of “variable” thickness projections may be useful in controlling the deflection characteristic of the first and second stage pad sections. Accordingly,  FIG. 5  illustrates tapered thickness profiles (in phantom) of baffles  127  and  227 . Specifically, baffles  127 ,  227  have a greater thickness dimension near their interface with outer shell liner  300 . Such a tapered configuration may permit the pad sections to start collapsing at the surfaces engaging outer shell  10  and the wearer&#39;s head, while resisting/attenuating the linear and rotational impact forces. 
     According to the present disclosure, CAD assembly  14  provides a first stage air transfer and energy dissipation mechanism in association with primary bellows unit  100  as well as a second stage air transfer and energy dissipation mechanism in association with secondary bellows unit  200 . In this regard, the primary air flow circuit of primary bellows unit  100  and the secondary air flow circuit of secondary bellows unit  200  facilitate this dual stage air transfer and energy dissipation system. The first and second air flow circuits are interconnected via the air transfer holes in the inner shell liner. Those skilled in the art will appreciate that the specific number, arrangement, size and configuration of the first stage pads (and corresponding primary bellows chambers) and specific number, arrangement, size and configuration of the second stage pads (and corresponding secondary bellows chambers) shown are merely intended to be exemplary in nature. Likewise, the size and air flow characteristics associated with the air charge holes, the air bridge channels, and the air transfer holes can be selected to provide metered and controlled air transfer through CAD assembly  14  to assist in optimizing impact damping and energy dissipation. 
     In operation, compression of CAD assembly  14  occurs when the head of a wearer of protective helmet  10  encounters an impact which forces the head to move in relation to an angle of impact. This action results in resilient collapse of the pad sections and forces a resilient cushion of regulated and controlled ambient air to be transferred to adjacent bellows chambers, thereby distributing the impact force over a larger area so as to delay and dissipate the impact away from the head of the helmet wearer. CAD assembly  14  creates a multi-stage “time delayed” impact dissipation that is operable for continuously transferring air by filling and subsequently refilling the bellows chambers until the impact has been dispersed. 
     Referring to  FIGS. 17A and 17B , the movement of CAD assembly  14  during, or in response to, a rotational force/acceleration impact exerted on protective helmet  10  is addressed. While linearly directed forces/accelerations of CAD assembly  14  are addressed above, the present disclosure provides a further benefit when helmet  10  is exposed to a rotational impact. Much like a boxer getting hit with a hook, the head of a person wearing helmet  10  can twist. Such rotational and centrifugal movement of the head within helmet  10  is minimized due to CAD assembly  14  providing a “suspended” function due to the elasticity of the stage one and stage two pad sections associated with outer bellows unit  100  and inner bellows unit  200  relative to inner shell liner  300 . An example of angular movement of CAD assembly  14  relative to the wearer&#39;s head is shown by alpha “α” in  FIG. 17B . Accordingly, compression of adjacent pad sections in concert with elastic deflection thereof, functions to limit the intensity of a rotational force exerted on outer shell  12  of helmet  10 . 
     CAD assembly  14  can be a modular assembly that can be easily installed in, or removed from virtually any type of outer shell portion of a helmet. This modularity permits different impact damping characteristics to be established by simply selecting from one or more differently sized or configured primary bellows unit  100 , secondary bellows units  200  and inner shell liners  300  to provide optimal comfort and address both adult and youth requirements. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.