Helmet

Abstract

A helmet 100 includes a helmet shell 16, an outer liner layer 14 fixed inside the helmet shell 16; and an inner liner layer 12 positioned against the outer liner layer 14; the outer liner layer 14 having a dome-like concave curved internal surface; the inner liner layer 12 having a dome-like convex curved external surface; the said surfaces of the inner and outer liner layers 12, 14 being substantially spherical where they overlap for allowing rotational sliding movement of the inner liner layer against the outer liner layer; a rotation-limiting mechanism being provided for limiting rotation between the inner and outer liner layers; and at least one of the said surfaces of the inner and outer liner layers 12, 14 having recesses 18 therein for weakening the layer and for facilitating crushing of the layer when a sufficiently large radial force is applied, loosening the inner liner layer 12 within the outer liner layer 14.

Claims

1. A helmet comprising: an ovaloid-shaped helmet shell, an outer liner layer fitted inside the helmet shell; and an inner liner layer positioned against the outer liner layer; the outer liner layer having a concave curved internal surface; the inner liner layer having a convex curved external surface; the outer and inner liner layers each including a front wall section, a back wall section, and two lateral side wall sections, in which the lateral side wall sections of the outer liner layer are truncated compared with the inner liner layer and compared with the front and back wall sections of the outer liner layer; wherein a lower edge of each lateral side wall section of the outer liner layer includes a curve extending towards an apex of the helmet, wherein the outer liner layer has a total height, wherein a peak of the curve of each lower edge is located within a top half of the total height, wherein a midpoint of the curve of each lower edge is located within the top half of the total height, and wherein two endpoints of the curve of each lower edge are located within a bottom half of the total height; said surfaces of the inner and outer liner layers being spherical where said surfaces of the inner and outer liner layers overlap for allowing rotational sliding movement of the inner liner layer against the outer liner layer; and a rotation-limiting mechanism connecting the inner and outer liner layers together, the rotation-limiting mechanism being provided for limiting rotation between the inner and outer liner layers.

2. A helmet as claimed in claim 1, in which at least one of the internal surface of the outer liner layer and the external surface of the inner liner layer has recesses therein for weakening the layer and for facilitating crushing of the layer when a radial force is applied, thereby loosening the inner liner layer within the outer liner layer.

3. A helmet as claimed in claim 2, in which the recesses are a plurality of elongate slots.

4. A helmet as claimed in claim 3, in which the slots are oriented in a front-to-back or side-to-side orientation on one or both of the external surface of the inner liner layer and the internal surface of the outer liner layer(s).

5. A helmet as claimed in claim 2, in which the recesses are formed in the internal surface of the outer liner layer.

6. A helmet as claimed in claim 1, in which the inner and outer liner layers are made from expanded polystyrene.

7. A helmet as claimed in claim 1, in which the lateral side wall sections of the inner liner layer have a non-spherical surface where the outer liner layer is truncated relative to the inner liner layer.

8. A helmet as claimed in claim 1, in which the helmet shell has an interior surface which is non-spherical.

9. A helmet as claimed in claim 8, in which the interior surface of the helmet shell is ovaloid.

10. A helmet as claimed in claim 1, including a chin strap.

11. A helmet as claimed in claim 1, in which the rotation-limiting mechanism for limiting rotation is at least one elastic connector which extends from the inner liner layer to the outer liner layer, across bottom edges of the respective layers.

12. A helmet as claimed in claim 11, in which the at least one elastic connector is an at least one elastic headband.

13. A helmet as claimed in claim 12, in which the at least one elastic headband extends to or across a bottom edge of the helmet shell.

14. A helmet as claimed in claim 11, in which the at least one elastic connector is part of the helmet shell or part of an additional outer liner layer, and the at least one elastic connector extends over an external surface of the outer liner layer.

15. A helmet as claimed in claim 11, in which the at least one elastic connector is made from elastane.

16. A helmet as claimed in claim 1, in which the helmet shell is rigid.

17. A helmet as claimed in claim 1, in which the helmet shell is flexible.

18. A helmet comprising: an ovaloid-shaped helmet shell, an outer liner layer fitted inside the helmet shell; an inner liner layer positioned against the outer liner layer; the outer liner layer having a concave curved internal surface, the outer liner layer having a front wall section, a back wall section, and two lateral side wall sections; the inner liner layer having a convex curved external surface; said surfaces of the inner and outer liner layers being spherical where said surfaces of the inner and outer liner layers overlap for allowing rotational sliding movement of the inner liner layer against the outer liner layer; the helmet shell having a non-spherical interior surface, and the outer liner layer being rotatable against the non-spherical interior surface of the helmet shell for absorbing rotational forces; wherein a lower edge of each lateral side wall section of the outer liner layer includes a curve extending towards an apex of the helmet, wherein the outer liner layer has a total height, wherein a peak of the curve of each lower edge is located within a top half of the total height, wherein a midpoint of the curve of each lower edge is located within the top half of the total height, and wherein two endpoints of the curve of each lower edge are located within a bottom half of the total height; and at least one elastic connector comprising a stretchable rotation-limiting member connecting the inner and outer liner layers together, the stretchable rotation-limiting member being provided for limiting rotation between the inner and outer liner layers.

19. A helmet comprising: an ovaloid-shaped helmet shell, an outer liner layer fitted inside the helmet shell; and an inner liner layer positioned against the outer liner layer; the outer liner layer having a concave curved internal surface; the inner liner layer having a convex curved external surface; the outer and inner liner layers each including a front wall section, a back wall section, and two lateral side wall sections, in which the lateral side wall sections of the outer liner layer are truncated compared with the inner liner layer and compared with the front and back wall sections of the outer liner layer; said surfaces of the inner and outer liner layers being spherical where said surfaces of the inner and outer liner layers overlap for allowing rotational sliding movement of the inner liner layer against the outer liner layer; the helmet shell having a non-spherical interior surface, and the outer liner layer being rotatable against the non-spherical interior surface of the helmet shell for absorbing rotational forces; wherein a lower edge of each lateral side wall section of the outer liner layer includes a curve extending towards an apex of the helmet, wherein the outer liner layer has a total height, wherein a peak of the curve of each lower edge is located within a top half of the total height, wherein a midpoint of the curve of each lower edge is located within the top half of the total height, and wherein two endpoints of the curve of each lower edge are located within a bottom half of the total height; and at least one elastic connector comprising a rotation-limiting mechanism connecting the inner and outer liner layers together, the rotation-limiting mechanism being provided for limiting rotation between the inner and outer liner layers.

20. A helmet as claimed in claim 19, in which at least one of the internal surface of the outer liner layer and the external surface of the inner liner layer has recesses therein for weakening the layer and for facilitating crushing of the layer when a radial force is applied, thereby loosening the inner liner layer within the outer liner layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which:

(2) FIG. 1a shows a perspective view of a helmet liner according to the invention, the inner and outer liner layers being located in a substantially central position;

(3) FIG. 1b shows a perspective view of the helmet liner of FIG. 1a, the inner liner layer having been rotated within the outer liner layer;

(4) FIG. 2 shows the interior surface of the outer liner layer of the helmet liner of FIGS. 1a and 1b;

(5) FIG. 3 shows a side view of the helmet liner of FIGS. 1a and 1b;

(6) FIG. 4 shows a helmet incorporating the helmet liner of FIGS. 1a and 1b, in use on a person's head; and

(7) FIG. 5 shows an underside view of the helmet of FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENT(S)

(8) Referring firstly to FIGS. 1a and 1b, a helmet liner is indicated generally at 10. The liner includes an inner liner layer 12 which is positioned against and rotatable within an outer liner layer 14. In FIG. 1b the inner liner layer 12 is seen rotated about the Y axis as indicated on the Figures, but it can also be rotated about the X axis in the same way. The outer surface of the inner liner layer and the inner surface of the outer liner layer are substantially spherical where they overlap, allowing rotation of the surfaces against each other. There are no components disposed between the inner and outer liner layers. The liner 10 is designed to fit within a helmet shell 16, seen in FIG. 4.

(9) FIGS. 2 and 3 more clearly show the shape of the inner 12 and outer 14 liner layers. In particular, from FIG. 2 it can be seen that the outer liner layer 14 includes a central section 14a, which in use is at the top of the helmet, above the wearer's head. A front wall section 14b and a rear wall section 14c extend from the central section 14a, the front and rear wall sections 14b, 14c being substantially vertical, in front and behind a wearer's head in use. The outer liner layer 14 also includes lateral side sections 14d and 14e. FIG. 2 shows that the lateral side sections 14d, 14e are substantially truncated, and do not extend a significant vertical distance down the sides of the wearer's head in use.

(10) The central portion and the front, back and lateral side wall portions of the inner liner layer are similarly labelled 12a, 12b, 12c, 12d, 12e.

(11) It is clear from FIG. 2 that the interior surface of the outer liner layer is not the same shape as the exterior surface of the outer liner layer. The interior surface is substantially spherical, where it rotates against the inner liner 12. The exterior surface is substantially ovaloid, to conform with the shape of the outer shell 16 which is seen in FIG. 4. Likewise, as seen in FIGS. 1a and 1b, the inner liner 12 has a substantially ovaloid interior shape for conforming to the shape of a human head. The exterior shape of the inner liner 12 is substantially spherical where it overlaps with the outer liner layer, but at the lateral sides in the positions where the outer liner layer is cut away, the spherical shape of the surface is interrupted. The overall shape of the inner and outer liners, joined together, is substantially ovaloid for fitting inside a helmet shell 16 of that general shape.

(12) A lower edge of each lateral side wall section of the outer liner layer 14 includes a curve extending towards an apex of the helmet 100, wherein the outer liner layer 14 has a total height, wherein a peak of the curve of each lower edge is located within a top half of the total height, wherein a midpoint of the curve of each lower edge is located within the top half of the total height, and wherein two endpoints of the curve of each lower edge are located within a bottom half of the total height.

(13) Because the helmet liner 10 as a whole has substantially ovaloid exterior and interior surfaces, but the interface surfaces between the inner and outer liner layers 12, 14 are substantially spherical, the outer liner layer 14 has generally thicker front and back end walls 14b, 14c, whereas the inner liner layer has generally thicker lateral side walls 12d, 12e.

(14) Recesses 18 are provided in the interior surface of the outer liner layer 14. In this embodiment, the recesses 18 are elongate slots and all the recesses run in straight lines on the X-Y plane, projected onto the curved surface of the outer liner layer 14. Recesses run between the lateral sides 14d, 14e of the outer liner layer 14 and between the front and back edges of the outer liner layer. Other arrangements of recesses are possible, but this arrangement is found to be particularly advantageous.

(15) FIG. 3 shows a side view of the complete helmet liner 10, and shows the substantial portion of the side wall 12e of the inner liner layer 12 which is not positioned against the interior surface of the outer liner layer 14. When the liner forms part of a helmet, as shown in FIGS. 4 and 5, this part of the inner liner layer is disposed directly against the hard outer shell 16.

(16) FIGS. 4 and 5 show a complete helmet 100 which incorporates the helmet liner 10. This embodiment includes a hard outer shell 16, and is particularly designed for use in horse riding. The outer appearance of the helmet is a similar in size and shape to many known horse riding helmets.

(17) It is envisaged that different types of outer shell 16 may be provided for different types of helmet. For example, a cycle helmet incorporating the invention may have a much thinner and more flexible outer shell than the hard outer shell 16 shown in this embodiment.

(18) The helmet 100 further includes an elastane headband 20, which is fixed around an edge of the interior surface of the inner liner layer 12 and around an edge of the outer surface of the outer liner layer 14. In other words, the elastane headband 20 holds the inner and outer liner layers 12, 14 together at their edges, and stretches as the layers 12, 14 rotate with respect to each other. In this way, the elastane headband 20 provides increasing resistance to rotation as the layers rotate relative to each other during an impact and acts as an elastic connector.

(19) A chin strap 22 is provided for holding the helmet on the wearer's head. The chin strap 22 is of a common design for horse riding helmets.

(20) In use, during an impact, the helmet protects the head against rotational forces by providing an extremely fast response to reduce peak rotational acceleration. The elastane headband and scraping of the outer liner layer 14 against the helmet shell 16 absorb the rotational forces, protecting the head. If the impact is particularly severe, the ribs formed between the recesses 18 in the outer liner layer 14 will collapse, loosening the rotational interface between the layers 12, 14 and reducing the resistance to rotation.

(21) At the same time, the ribs between the layers increase the performance of the helmet in terms of protection from radial impact. The ribs form a weakened region between the outer and inner surfaces of the helmet, allowing the helmet liner to absorb energy by plastic deformation substantially throughout its entire thickness.

(22) The words comprises/comprising and the words having/including when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

(23) It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

(24) The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims.