Collapsible helmet and corresponding production method
A collapsible helmet is formed as an arcuate layered structure openable into a honeycomb protective configuration. The arcuate layered structure is formed from a number of arcuate segments each covering only part of the helmet. Each segment is oriented so that an extensional cell direction of the honeycomb structure is radial for a middle-region. The arcuate layered structure is preferably bounded by arcuate end plates which engage with each other when the helmet is open to form a rigid loop encircling a bottom edge of the helmet.
1 . A collapsible helmet deployable for protecting a head of a user, the helmet comprising:
an arcuate layered structure configured to have a collapsed state and openable therefrom into a honeycomb protective configuration for encompassing at least an upper part of the head, said arcuate layered structure spanning an angular range from a first end to a second end in both said collapsed state and in said protective configuration,
said arcuate layered structure being formed at least in part from a plurality of arcuate segments each having an angular span less than said angular range, each segment having a plurality of layers, each of said layers being joined to adjacent layers along lines of attachment, said lines of attachment being staggered between successive of said layers so as to define, when opened, a honeycomb structure with an extensional cell direction, said extensional cell direction being a radial direction for a mid-region of each of said arcuate segments,
said arcuate layered structure including at least two of said arcuate segments deployed sequentially between said first end and said second end so that said extensional cell directions form an angle of no more than 45 degrees to radial directions of said arcuate layered structure across said angular range, wherein said arcuate layered structure has a helmet thickness in the radial direction, and wherein adjacent of said arcuate segments are formed with complementary overlap regions, each of said overlap regions having a thickness less than said helmet thickness, said complementary overlap regions being deployed in overlapping relation so as to provide a combined thickness greater than said thickness of each of said overlap regions.
2 . The collapsible helmet of claim 1 , wherein said thickness of each of said complementary overlap regions is tapered.
3 . The collapsible helmet of claim 1 , wherein said arcuate layered structure comprises a first plurality of said arcuate segments spanning said angular range from said first end to said second end and a second plurality of said arcuate segments spanning said angular range from said first end to said second end, said second plurality of said arcuate segments being bonded to said first plurality of said arcuate segments such that each of said first and second pluralities of said arcuate segments provides a part of an overall width of said honeycomb protective configuration, and wherein said overlap regions of said first plurality of said arcuate segments do not coincide with said overlap regions of said second plurality of said arcuate segments.
4 . The collapsible helmet of claim 1 , wherein said at least two arcuate segments are deployed so that said extensional cell directions form an angle of no more than 40 degrees to radial directions of said arcuate layered structure across said angular range.
5 . The collapsible helmet of claim 1 , wherein said at least two arcuate segments are deployed so that said extensional cell directions form an angle of no more than 35 degrees to radial directions of said arcuate layered structure across said angular range.
6 . The collapsible helmet of claim 1 , wherein said at least two arcuate segments include at least three arcuate segments deployed sequentially between said first end and said second end so that said extensional cell directions form an angle of no more than 30 degrees to radial directions of said arcuate layered structure across said angular range.
7 . The collapsible helmet of claim 1 , wherein said arcuate layered structure includes a first set of at least two of said arcuate segments deployed sequentially between said first end and said second end and a second set of at least three of said arcuate segments deployed sequentially between said first end and said second end, said first set of arcuate segments and said second set of arcuate segments being deployed in overlapping relation so that joints between adjacent arcuate segments of said second set are staggered relative to joints between adjacent arcuate segments of said first set.
8 . A collapsible helmet deployable for protecting a head of a user, the helmet comprising:
an arcuate layered structure configured to have a collapsed state and openable therefrom into a honeycomb protective configuration for encompassing at least an upper part of the head, said arcuate layered structure spanning an angular range from a first end to a second end in both said collapsed state and in said protective configuration,
said arcuate layered structure being formed at least in part from a plurality of arcuate segments each having an angular span less than said angular range, each segment having a plurality of layers, each of said layers being joined to adjacent layers along lines of attachment, said lines of attachment being staggered between successive of said layers so as to define, when opened, a honeycomb structure with an extensional cell direction, said extensional cell direction being a radial direction for a mid-region of each of said arcuate segments,
said arcuate layered structure including at least two of said arcuate segments deployed sequentially between said first end and said second end so that said extensional cell directions form an angle of no more than 45 degrees to radial directions of said arcuate layered structure across said angular range;
a pair of arcuate end plates bonded to outer surfaces of said arcuate layered structure, opposite ends of each of said arcuate end plates carrying complementary parts of an engagement configuration,
wherein, in a collapsed stated of the helmet, said arcuate end plates are brought together with said arcuate layered structure between them,
and wherein, when said honeycomb structure is open, said engagement configurations at ends of said arcuate end plates engage so that said arcuate end plates form a rigid loop encircling a bottom edge of the helmet, wherein, in said rigid loop, said arcuate end plates form a locking angle between them greater than 180 degrees around which said honeycomb structure is stretched.
9 . The collapsible helmet of claim 8 , wherein said engagement configurations are configured to allow engagement of said complementary parts of said engagement configurations when said arcuate end plates are temporarily brought to an engagement angle which is greater than said locking angle, and wherein resilient tension in said honeycomb structure biases said arcuate end plates to return from said engagement angle to said locking angle.
10 . A collapsible helmet deployable for protecting a head of a user, the helmet comprising:
an arcuate layered structure openable into a honeycomb protective configuration for encompassing at least an upper part of the head, said arcuate layered structure being formed from layers joined to adjacent layers along staggered lines of attachment so as to define, when opened, a honeycomb structure; and
a pair of arcuate end plates bonded to outer surfaces of said arcuate layered structure, opposite ends of each of said arcuate end plates carrying complementary parts of an engagement configuration,
wherein, in a collapsed stated of the helmet, said arcuate end plates are brought together with said arcuate layered structure between them,
and wherein, when said honeycomb structure is open, each said engagement configurations at ends of said arcuate end plates engages so that said arcuate end plates form a rigid loop encircling a bottom edge of the helmet.
11 . The collapsible helmet of claim 10 , wherein, in said rigid loop, said arcuate end plates form a locking angle between them greater than 180 degrees around which said honeycomb structure is stretched.
12 . The collapsible helmet of claim 11 , wherein said engagement configurations are configured to allow engagement of said complementary parts of said engagement configurations when said arcuate end plates are temporarily brought to an engagement angle which is greater than said locking angle, and wherein resilient tension in said honeycomb structure biases said arcuate end plates to return from said engagement angle to said locking angle.