Abstract
The present invention provides a head protection helmet comprising an impact resistant shell comprising: a cavity for accommodating a user's head and an array of crushable bodies having a hollow closed configuration, e.g. flutes in corrugated material 14,16, the crushable bodies each having an axis that extends outwardly from the cavity to absorb impact forces exerted along the direction of the axis.
Claims
1. A head protection helmet comprising an impact resistant shell comprising: a cavity for accommodating a user's head; and an array of cells, each having four sides and an axis that extends outwardly from the cavity to absorb impact forces exerted along the direction of the axis; wherein the cells are formed by a plurality of intersecting arc-shaped ribs overlying the cavity, wherein each rib of the plurality of ribs extends outwards from the cavity and includes an array of crushable bodies, each crushable body having a hollow closed configuration.
2. A helmet as claimed in claim 2, wherein each rib of the plurality of ribs is formed of crushable sheet material including a plurality of sheets of crushable board, the plurality of sheets of crushable board including a first sheet extending outwards from the cavity and a second sheet extending outwards from the cavity adjacent the first sheet; and wherein each rib of the plurality of ribs also includes a first connector body connecting the first sheet to the second sheet; wherein the first sheet, the second sheet and the first connector body form the array of crushable bodies.
3. A helmet as claimed in claim 3, wherein the crushable sheet material includes a single layer of crushable bodies.
4. A helmet as claimed in claim 3, wherein the ribs each include multiple layers of crushable bodies, the plurality of sheets of crushable board of each rib including a third sheet extending outwards from the cavity adjacent the second sheet opposite the first sheet, and each rib of the plurality of ribs includes a second connector body connecting the second sheet to the third sheet forming a second array of crushable bodies.
5. A helmet as claimed in claim 2, wherein the crushable bodies have an axis that lies generally orthogonal to the plane of the ribs.
6. A helmet as claimed in claim 2, wherein the plurality of ribs comprises ribs extending axially between the front and back of the head cavity and ribs extending laterally between two opposed sides of the head cavity, the axial and lateral ribs intersecting at crossed halved joints.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0035] There will now be described, by way of example only, several embodiments of the present invention by reference to the accompanying drawings in which:
[0036] FIG. 1 shows part of a helmet, that is to say an impact resistant shell in accordance with the present invention, viewed from the front and one side;
[0037] FIG. 2 shows the helmet of FIG. 1 viewed from below;
[0038] FIG. 3 is an end view of corrugated fibre board that may be used in the helmet of FIGS. 1 and 2;
[0039] FIG. 4 is a partly cutaway view of part of an arc-shaped rib made of fibre board having a honeycomb core that may be used in the helmet of FIGS. 1 and 2;
[0040] FIG. 5 shows the joint between two arc-shaped ribs used in the helmet of FIGS. 1 and 2.
[0041] FIG. 6 is a schematic view of a helmet in accordance with the present invention using the shell shown in FIGS. 1 and 2;
[0042] FIGS. 7 and 8 show, schematically, an alternative arrangement to the impact resistant shell of FIGS. 1 and 2; and
[0043] FIGS. 9a and 9b shows schematically a shock indicator for use as a helmet.
DETAILED DESCRIPTION
[0044] The helmet of the present invention includes an impact resistant shell that is able to absorb some of the forces exerted on a helmet during a collision with another object, which may be the road, a pavement, a pedestrian or another vehicle. As mentioned above, the present invention is not limited to a cycling helmet but cycling will be used to exemplify the diverse applications for which the helmet may be used, some of which are set out above.
[0045] Referring initially to FIGS. 1 and 2, which show the shell from one side and from below, respectively, the impact resistant shell 10 of the helmet includes a rim 12 made of a solid fibre board. The rim may be made in a single piece or in multiple pieces (as shown in FIGS. 1 and 2) that are joined together at connection 13, which is most clearly shown in FIG. 2. The joint 13 is a simple tongue-and-groove joint that includes a tongue 13a on one piece of the rim that slots into a groove 13b cut into the end of a second piece of the rim.
[0046] The rest of the impact resistant shell 10 is made up (a) of series of axial ribs 14 extending between the front 18 and the back 19 of the helmet and (b) a series of lateral ribs 16 extending between the two sides 20 of the helmet. As can be seen, the ribs are arranged in planes that extend radially outwards from the helmet and form an intersecting lattice of shock absorbing ribs; the lattice can be seen as an array of 4-sided shock-absorbing cells 23. The axial ribs 1 of FIGS. 1 and 2 come together at the front 18 and the rear 1 of the helmet. Likewise, the lateral ribs 16 come together at the two sides 20 of the helmet. The ends of the ribs 14, 16 slot into grooves 21 in the rim 12. They may be held in the grooves 21 by adhesive.
[0047] The ribs 14,16 are arc shaped and the insides of the ribs forms a head cavity 30. As is clear from FIGS. 1 and 2, the ribs 14, 16 intersect with each other. The joints at these intersecting points are shown in an exploded view in FIG. 5. The axial ribs 14 have a groove 34 cut in the concave side of the rib while the lateral ribs 14 have a groove 32 cut in their convex faces. The grooves 32, 34 can then be slotted into each other together to form a halved cross joint, which means that neither of the ribs 14, 16 is cut completely through in order to provide the intersection. The grooves in the ribs 14,16 can extend radially from the centre of the cavity 30. In FIG. 5, the grooves 32,34 are shown to extend at right angles to the plane of the respective ribs but, as can be seen in FIG. 1, the groove may extend in a non-orthogonal direction to the plane of the ribs that forming an intersection. The sizes of the grooves 32, 34 should accommodate the other rib and the ribs may be held in place either by friction or by adhesive or by a mechanical element. As can be seen in FIG. 1, some of the grooves 34 in the ribs 14 (as indicated by the reference number 34a in FIG. 1) are larger than necessary to accommodate the corresponding lateral ribs 16 and this provides some play between the ribs which can therefore absorb more impact energy in the case of an accident. Furthermore, it assists in assembling the shell 10.
[0048] The ribs 14, 16 may be made of corrugated fibre board, as shown in FIG. 3. Corrugated fibreboard includes at least one undulating section 28 sandwiched between flat fibre board layers 31 to form a series of flutes 29. It possible to build up a number of such layers in a unitary corrugated fibre board (FIG. 3 includes two such undulating sections). The thickness of the material forming the undulations 28 and the thickness of the flat board 1 should be chosen to give the degree of shock resistance and crumpling need to absorb the type of forces exerted during a collision.
[0049] Alternatively, the ribs can be made from honeycomb fibreboard, which is shown in FIG. 4 and has a pair of fibreboard face sheets 31; only one face sheets is shown in FIG. 4 and that face sheet is shown partly cut away so that the internal honeycomb array 33 is visible. The honeycomb connects together the face sheets 31 and may be made of plastic or paper or cardboard. It is glued to the face sheets 31 in a known manner. Again, it possible to build up a number of sheets and honeycomb layers in a unitary corrugated fibre board so that three or more sheets 31 are included in each rib, each adjacent pair of sheets sandwiching between them a honeycomb layer.
[0050] Turning back to FIGS. 1 and 2 and dealing with the case in which the ribs are made of corrugated fibreboard, the flutes 29 in the ribs may extend in horizontal, vertical, axial or lateral directions or diagonally within the helmet. The flutes in alternate lateral ribs 1 extend horizontally (i.e. in the direction between the two sides of the helmet) and such flutes resist especially lateral forces on the helmet. The flutes in the other lateral ribs 16 extend vertically and such flutes resist vertically acting forces. Likewise in some of the axial ribs 14, the flutes extend horizontally which are resistant to forces impacting on the front or rear of the helmet while the flutes on the other ribs extend vertically and such flutes resist vertically acting forces. Generally, alternate ribs should have vertically-extending flutes and the remaining ribs should have horizontally-extending flutes, although the two central axial ribs 14 may have vertically extending ribs to resist forces exerted down onto the crown of the helmet.
[0051] When the ribs are made of the honeycomb material shown in FIG. 4, the honeycomb cells will extend at right angles to the plane of the ribs.
[0052] The impact resistant shell shown in FIGS. 1 and 2 can absorb impact forces from any direction and can crumple as a result, thereby absorbing the energy of the impact and protecting the user's head.
[0053] In order to provide waterproofing to the fibre board, an outer shell or layer 50 (see FIG. 6) can overlay the shell 10 shown in FIGS. 1 and 2 and which can be fastened to the shell 10, either permanently or temporary. The outer shell 50 should be provided with ventilation holes (not shown) that preferably line up with the spaces between the ribs 14, 16 of the shell 10. In addition, the cardboard used to make the shell 10 may be waterproof by the application of a waterproofing or water resistance layer (not shown).
[0054] The outer shell 50 may be made of acrylic material but it could also be made of other materials for example, polypropylene or ABS having a stiffness coefficient higher than that of the material used to make the impact resistant shell 10 and so absorbs part of the initial shock waves when an impact occurs. Slots 52 may he provided in the outer shell in order to attach straps (not shown) that can be secured under the user's chin to hold the helmet on the user's head
[0055] An inner shell 55 may be provided between the user's head and the cavity 30 within the impact resistant shell 10 in order to provide comfort to the user, to dissipate forces being transmitted through the edges of the ribs 14, 16 directly to the user's head and to ensure that the helmet fits snugly. The inner shell may be made of padding, for example a layer of foam and or woven or non-woven fabric.
[0056] As is evident from the discussion above, the impact resistant shell 10 shown in FIGS. 1 and 2, when made with the ribs of corrugated fibreboard, provides strength and impact resistance by means of the flutes within corrugated material. In addition impact strength is provided by holding the ribs in a fixed array of 4-sided cells 23, each cell having an axis that extends away from the inner cavity 30 of the helmet and generally radially outward from the cavity. In the case of the ribs being made of the honeycomb material shown in FIG. 4, the strength of the helmet will mostly be provided by this array of 4-sided cells, with the honeycomb pattern within the ribs resisting the collapse of the ribs and thereby maintaining the face sheets 31 in a space-apart parallel configuration, which increases the impact resistance of the individual ribs. In a variant of the cellular structure just described, the shell 10 may be made of an array of cylindrical tubes (see FIGS. 7 and 8) that are arranged in a dome shape and the under surface (not shown) forms a head cavity. The tubes 100 are collected in array with the inner ends of the tubes lying at different elevations in order to provide the shell with a hollow dome-shape. The axis of the various tubes shown in FIG. 9 all extend vertically and are intended to resist vertical forces. However, they can be embedded in a matrix so that they extend in different directions from the head in order to provide protection against forces from different directions.
[0057] The tubes, instead of being cylindrical, may be frustoconical, which has the advantage that, when the tubes are gathered together with the larger faces φx (see FIG. 8) pointing outwardly and the smaller faces φy pointing inwardly, the axes of the frusto cones point in different radial directions.
[0058] The tubes 100 are hollow and are generally made of fibre board such as paper or cardboard. Tubes made of this configuration can be incredibly strong and can transmit an impact force directly to the user's head without absorbing it. In order to provide some measure of impact absorption, a crumple zone may be introduced in the side walls of the tubes. So that the tubes crumple within their own diameter, it is preferred that the crumple zone is helical in shape and may be formed, as can be seen in FIG. 8, by helically arranged holes 102.
[0059] The tubes 100 formed into an impact resistant shell may be incorporated into a helmet with an outer shell 50 and padding 55 (see FIG. 6).
[0060] The outside and inside surfaces of an impact resistant shell formed from an array of tubes 100 may be sanded to provide the hollow dome shape.
[0061] Turning finally to FIGS. 9a and 9b, an arrangement is shown that can detect when a helmet has been subject to impact forces (or shock) exceeding a threshold, indicating that the helmet should be replaced or at least the impact resistant shell 10 should be replaced. As shown in FIG. 9a, which shows the whole shock indicator; the indicator includes a central chamber 124 having a number of shock indicator flasks 120 spaced around it and preferably evenly spaced around it. FIG. 9b, is a schematic drawing showing one of the flasks 120 and part of the central chamber 124. Each flask includes a space 122 that is filled with coloured liquid that communicates with the central chamber 124 via a capillary bore 128. The common chamber 124 is initially empty. Because of the size of the capillary bore 128 and the viscosity of the liquid, the liquid is generally retained within the space 122. However, if a particular flask is subject to an acceleration or deceleration (in the case of the orientation shown in FIG. 9a in the vertical direction), the coloured liquid can be forced through the capillary bore into the previously empty common chamber 124. The presence of the coloured liquid within the chamber 124 indicates that the flask has been subject to excessive shock and that the helmet therefore needs replacing. The liquid may be such that it adheres to the walls in the common chamber 124 thereby clearly showing that one of the flasks 120 has been subject to an excessive shock. The indicator of FIGS. 9a and 9b can be incorporated into a holder that fits into a cavity within the helmet (not shown) and is held within that cavity by latches (again not shown). The indicator 120 can be small (of the order of a few centimetres) and so it can easily be accommodated in a relatively small cavity within a helmet. The common chamber 124 can be smaller than shown. A transparent or translucent lens (not shown) may be provided on the outside of the helmet to view the common indicator chamber 124; the magnification makes it easier to see whether or not liquid is located within the chamber 124.
