This invention relates to protective helmets of a type used by motor cycle riders and racing car drivers.

The problem to which this invention is directed arises from investigative work in which there appears to be substantial potential that the design presently being used for protective helmets may be a causative factor in some fatalities.

A full face helmet of conventional current design normally includes a chin bar (sometimes referred to as a face bar) which is a projecting part extending around the chin of a user and having as its purpose protection against abrasion of the lower face.

Following our investigative work, it appears that this arrangement causes fatal injuries in certain circumstances.

We have deduced that the reason for this arises firstly because of the essentially rigid nature of the chin bar, the way that this is connected through to a remainder of the helmet, and the way in which it is connected to a chin strap.

In some accidents an impact on the chin bar can be transmitted directly as a lifting force through the chin strap on to the jaw of the user and through this through the mandibular condyles in such a way that there is a force transmitted through to the skull base which in turn causes a fracture along the floor of the middle cranial fossa on which the brain rests.

With a lifting of the skull base, this will cause separation of the brain from the brain stem which causes immediate death.

According to this invention there is a proposed helmet including a chin bar and chin strap characterized in that there are means to effect substantial energy absorption upon deformation of parts of the helmet in the event of a frontal force being effected against the chin bar.

Preferably the helmet includes means to interengage with respect to the cheek bones of a user whereby to impede rearward movement of the helmet relative to the head of a wearer in the event of a rearward pressure on the helmet through a chin bar.

In preference, such an arrangement includes two cheek bars one of which extends from each respective side of the helmet and each of which is located so as to be normally in a sufficiently close relationship with the cheek bone of a user so that in the event of significant forces occurring on the helmet in a rearward direction, these will inevitably intersect against the cheek and significantly retard such further movement.

The cause of the fatalities hitherto has been a combination of the arrangement of the outer helmet which includes a rigidly connected chin bar, and an interconnected strap which extends below the chin which of course transmits the substantially upward force in the event of an accident trauma.

fn preference, the cheek bars are arranged firstly so that they will retard the relative motion of a helmet from a rearward upward direction.

One difficulty with such an arrangement is that there a number of different sizes of heads that will have to be accommodated and to this end, there is firstly provided a cushioning material on a rear face of such cheek bars so as to spread the load in the event of any accident occurring over a significant part of the respective cheek bone.

Further however there is envisaged the concept of cheek bars that can be varied in position and can be interlocked in selected positions which are appropriately comfortable for a user but adequately positioned in the event of an accident for the purposes stated.

Within this general concept, there can be provided further means by which to separate any forces resulting from impingement of the chin bar against an impacting obstacle and the chin strap.

In a further arrangement in accord with this invention, there is provided an inner helmet means incorporating respective cheek bars adapted to engage against respective cheek bones of a user and to be integrally secured one with respect to the other by an inner helmet part, an outer helmet including a forwardly extending chin bar, and an elastomeric connector between said inner helmet means and said outer helmet means.

In preference, such inner helmet means and outer helmet define a space there between which is filled with an appropriate shock absorbing material.

According to a further arrangement, there are provided energy absorption means within the structure of the face bar and further, the chin strap is anchored in such a way that it will cause substantial inward defamation of the helmet at its anchor point, and such therefore that, energy absorption occurs by such means.

For a better understanding of this invention reference will now be made to two embodiments which are described with the assistance of drawings in which:

FIGURE 1 is a side elevation in which the shape of the helmet according to a standard design is shown in outline with the details of the human head is also shown in continuous outline so that the forces effective during the impact on the chin bar can be seen,

FIGURE 2 is the same view as in Figure 1 with, however, the further stage being reached in which the fractures expected are shown,

FIGURE 3 is a cross sectional view looking from above of a helmet according to the first embodiment located around in schematic layout, the skull of the user,

FIGURE 4 is a side elevation in part cross section and partly schematic showing the arrangement of the same helmet as in FIGURE 3 located on the head of the user,

FIGURE 5 shows the arrangement for a second embodiment showing in schematic detail the use of chin bars attached to a helmet, and showing the a

position at which the cheek bars are in their normal position.

FIGURE 6, is the same cross sectional view as in FIGURE 5 showing however the cheek bars in a diverted position.

FIGURE 7 is a side view of the helmet of the second embodiment.

Referring in detail to the drawings and in particular FIGURES 3 and 4, there is shown here a helmet 1 which includes an inner helmet means 2 which is comprised of relatively rigid plastics materials in relatively thin sheet form but adapted to conform to the external shape of the skull of the user and in particular such that there are two cheek bars at 3 and 4 which are adapted to fit around and both engage against and slightly underneath the cheeks of the person shown at 5.

This inner helmet means 2 is secured and maintained with respect to the head of the person 5 by a chin strap 6.

This includes means to tighten the strap which are not specifically shown.

An outer helmet 7 is connected to the inner helmet means 2 by two blocks 8 and 9 which are comprised of an elastomeric material such as polyurethane plastics material or such that in the event of significant relative forces occurring between the outer helmet means 7 and the inner helmet means 2, then these elastomeric blocks 8 and 9 will be caused to deform and provide significant energy losses as well as relative loss of impact forces between the two.

In addition to this however there is energy loss absorbing material interposed between the respective shells comprising the inner helmet means 2 and the outer helmet means 7 and this is shown at 10 and comprises foam semi-rigid plastics material.

With such an arrangement, the chin bar 11 it is rigidly connected to the outer helmet means 7, but nonetheless there are significant energy absorbing means between the outer helmet and the inner helmet means and the cheek bars retard further rearward relative movement action.

Referring to the second embodiment as shown in especially FIGURES 5, 6, and 7, this includes cheek bars 12 and 13 which are comprised integrally with the external shell of a crash helmet of traditional dimensions and type.

In particular then there are cheek bars 12 and 13 which project across the respective cheeks 14 and 15 of a user and there is provided a cushioning material of a resilient urethane foam at 16 and 17.

The energy losses are caused by deflection of the cheek bars to a position as shown in FIGURE 6 in dotted outline at 18 and 19 which is of course given simply by way of example.

An additional feature can be provided in this arrangement in which the chin strap is changed in position to become a neck strap and has its anchor point changed so that it is either at a rear of the helmet shape at 20 or in preference, it encircles some of the energy absorbing materials at 21 so that there is firstly a differing anchor point and more particularly, more energy absorption being caused by a compression of this material by a tightening of the chin strap or neck strap as the case might be.

With such an arrangement, the number of turns and shapes of the strap can be selected as appropriate.

From these two examples however, it will be seen that there can now be provided significant devices by which significant retardation of frontal forces against a chin bar by reason of engagement or interlocking or intersection with the cheek of a user.

From the description thus far given, it will be seen that the problem is to avoid transmission of the forces against the chin bar from being transmitted though the jaw bone to the skull base.

Referring then to Figures 1 and 2, there is shown according to the conventional helmet, a helmet 31 which as is traditionally the case is made of a material to resist substantial abrasion but which at the same time is manufactured to be

substantially rigid and to provide a substantially rigid interconnection through to the chin straps 33.

The chin strap 33 is conventionally made of a leather or substantially non extensible but pliable material by means which allow for pivotable freedom about a substantially horizontal axis at 34 but which otherwise will now allow any other freedom of movement.

The mandibular condyles 36 are therefore trapped into forcing part of the skull base which in turn causes a fracture along the floor of the middle cranial fossa with the result that the brain 38 will be lifted fracturing the spinal column at 39.

This then describes the problem to which the respective embodiments apply.