CA3120169A1 - Helmet liner - Google Patents

Abstract

A helmet liner includes a liner body having an impact absorbing bottom layer, a slippery intermediate layer and a top fabric layer. The intermediate layer overlies and is secured to the bottom layer. The top fabric layer overlies the intermediate layer. The top fabric layer has a perimeter and a central portion. The top fabric layer is secured on the perimeter leaving the central portion of the top fabric layer free to accommodate relative sliding movement of the intermediate layer. In the event of an impact, the slippery intermediate layer moves with a head of a wearer and kinetic energy is absorbed by the top fabric layer which remains stationary anchored to an interior surface of a helmet.

Description

TITLE
[0001] Helmet Liner FIELD

[0002] There is described a helmet liner, used to line a helmet which serves as protective head gear.
BACKGROUND

[0003] United States Patent 10,143,255 (Golnaraghi et al) describes a danger of injuries occurring to a head of a person wearing protective head gear as a result of rotational acceleration. The reason for this is that, upon impact, an outer interior surface of the protective head gear stops instantly, while the head keeps moving. The solution proposed by Golnaraghi et al is to provide an impact diverting mechanism which includes a top layer which attaches to the interior surface of the helmet and a bottom layer that attaches to the liner of the helmet.
The top layer is disposed adjacent to and mechanically connected to the bottom layer. Upon impact, the top layer shifts relative to the bottom layer. This relative movement dissipates kinetic energy. A preferred embodiment is described by Golnaraghi et al that has an intermediate layer positioned between the top layer and the bottom layer. The intermediate layer may include a liquid-gel lubricant to facilitate slipping movement of the top layer relative to the bottom layer.

[0004] This document is the culmination of several years of research into lubricants and other materials to facilitate slipping movement of the top layer relative to the bottom layer.
SUMMARY

[0005] There is provided a helmet liner which includes a liner body having an impact absorbing bottom layer, a slippery intermediate layer and a top fabric layer.
The intermediate layer overlies and is secured to the bottom layer. The top fabric layer overlies the intermediate layer. The top fabric layer has a perimeter and a central portion. The top fabric layer is secured on the perimeter leaving the central portion of the top fabric layer free to accommodate relative sliding movement of the intermediate layer.

Date Recue/Date Received 2021-05-28

[0006] The innovative aspect of the helmet liner described above is the use of a top fabric layer. At the start of the research, fabric would not have been considered suitable for the top layer. This was particularly the case when a liquid-gel lubricant was being used. However, the slippery intermediate layer slides freely on fabric. Even when the fabric is secured at the perimeter, the central portion of the fabric still accommodates sliding movement of the slippery intermediate layer. It is important to note that the research conducted in arriving at the above-described helmet liner determined that only a limited movement of 5mm to 15mm was sufficient to dissipate some of the kinetic energy and reduce rotational acceleration of the head.

[0007] If a greater range of movement is required to dissipate more kinetic energy in an intended application, there are a number of ways that this can be accommodated. For example, one could make the top fabric layer stretchable, such that the top fabric layer facilitates increased sliding movement of the slippery intermediate layer.

[0008] There are some immediate benefits in the use of the helmet liner, as described above. The helmet liners that use the liquid-gel lubricant are more difficult and more expensive to manufacture. More things can go wrong with helmet liners that use the liquid-gel lubricant.
If the seal confining the liquid-gel lubricant is compromised, the liquid-gel lubricant will leak out or the liquid-gel lubricant will dry out when exposed to air. In either event, movement of the top layer in relation to the bottom layer was adversely affected.

[0009] In all of the research, the helmet liner was attached to an interior surface of a helmet through the use of hoop and loop fasteners, commonly known by the Trademark brand name VELCRO fasteners. This attachment can be simplified when the top fabric layer is capable of serving as a loop portion of a hook and loop fastener and mates with a hook portion of the hook and loop fastener. The use of hook and loop fasteners actually improves the performance of the helmet liner when the top fabric layer serves as the loop portion of the hook and loop fastener. The hook portion anchors the top fabric layer which tends to localize the impact force (thus the sliding motion) and also ensures the sliding motion happens optimally in specific locations on the liner.

Date Recue/Date Received 2021-05-28 BRIEF DESCRIPTION OF THE DRAWINGS

[0010] These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:

[0011] FIG. 1 is atop plan view of a helmet liner.

[0012] FIG. 2 is a side elevation view, in section, of the helmet liner of FIG. 1.
DETAILED DESCRIPTION

[0013] A helmet liner generally identified by reference numeral 10, will now be described with reference to FIG. 1 and FIG. 2.
Structure and Relationship of Parts:

[0014] Referring to FIG. 1, helmet liner 10 has a liner body 12.
Referring to FIG. 2, when viewed in section, it can be seen that liner body 12 has an impact absorbing bottom layer 14, a slippery intermediate layer 16 and a top fabric layer 18. Slippery intermediate layer 16 overlies and is secured to bottom layer 14. Top fabric layer 18 overlies slippery intermediate layer 16.

[0015] Referring to FIG. 2, top fabric layer 18 has a perimeter 20 and a central portion 22.
Top fabric layer 18 is secured to either bottom layer 14, slippery intermediate layer 16, or both only at locations along perimeter 20. This leaves central portion 22 of top fabric layer 18 free to accommodate relating sliding movement of slippery intermediate layer 16. In order to suit most applications, a sliding movement of at least * must be achieved. Some fabrics are inherently more "slippery" and more readily accommodate sliding movement than other fabrics. The selection of the fabric material for top fabric layer 18 can, therefore, impact performance. Where increased sliding movement is desired, a stretchable fabric material may be selected for top fabric layer 18. This enables top fabric layer 18 to facilitate increased sliding movement of slipper intermediate layer 16 as top fabric layer 18 stretches.

[0016] Referring to FIG. 2, it is preferred that top fabric layer 18 is being capable of serving as a loop portion of a hook and loop fastener and mating with a hook portion 100 of the hook and loop fastener for the purpose of connecting to an interior surface 102 of a helmet 104.

Date Recue/Date Received 2021-05-28

[0017] After experimenting with various fabric materials looking for a fabric that is slippery, provides the desired amount of movement and is capable of serving as a loop portion of a hook and loop fastener, nylon and spandex blend fabrics and polyester and spandex blend fabrics were found to provide beneficial results.

[0018] There are various materials that are suitable for impact absorbing bottom layer 14.
The preferred material used during testing was a polymer foam and, more particularly, an open celled polymer foam. It will be appreciated that there are elastic materials and auxetic materials that would also be suitable.

[0019] There are various materials that are suitable for slippery intermediate layer 16. The preferred material used during testing was a polymer plastic and, more particularly, a thermoplastic.

[0020] Referring to FIG. 2, it was preferred that bottom layer 14 not be placed in direct contact with a human head. For that reason, a second fabric layer 24 was adhered to bottom layer 14. Second fabric layer 24 is for the comfort of the wearer and does not contribute to performance of helmet liner 10 in the event of an impact.
Operation:

[0021] Referring to FIG 2, in the event of an impact, interior surface 102 of helmet 104 will commence movement in a direction indicated by arrow 106 and then will come to an abrupt stop upon impact. A head 108 of a wearer will have commenced movement in the direction indicated by arrow 106. Helmet liner 10 protects head 108 of wearer by dissipating kinetic energy. Top fabric layer 18 is anchored to interior surface 102 of helmet 104 by hook portion 100 of a hook and loop fastener, which engages top fabric layer 18. As previously described, top fabric layer 18 serves as the loop portion of the hook and loop fastener. Impact absorbing bottom layer 14 with attached slippery intermediate layer 16 are attached to head 108 of the wearer. However, there is relative sliding movement between slippery intermediate layer 16 and top fabric layer 18. This results in slippery intermediate layer 16 moving with Date Recue/Date Received 2021-05-28 head 108 and kinetic energy being absorbed by top fabric layer 18 which remains stationary with interior surface 102 of helmet 104.
Test Data:

[0022] Helmet impact tests were performed using a guided free-fall oblique impact test rig dropping a helmet against an anvil at an impact angle of 45 degrees. The impact speed generated was 6.5 meters per second. A test was first conducted with a helmet having a standard helmet liner. This established a base line for comparing the performance of the helmet line described above. Tests were conducted in five impact locations and orientations:
1. front, 2. right side toward back, 3. left side toward back, 4. left side toward front, and 5. right side toward front. The rotational acceleration percentage reduction achieved by helmet liner 10 was as follows: 1. front an improvement of 22%, 2. right side toward back an improvement of 35%, 3. left side toward back an improvement of 6%, 4. left side toward front an improvement of 31% and 5. right side toward front an improvement of 45%. It is to be noted that in orientation #3 that improvement gained was only 6%. The reason for this is believed to be due to the shape of the helmet tested, which created a geometric lock reducing the amount of motion possible.

[0023] In this patent document, the word "comprising" is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article "a" does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements.

[0024] The scope of the claims should not be limited by the illustrated embodiments set forth as examples but should be given the broadest interpretation consistent with a purposive construction of the claims in view of the description as a whole.

Date Recue/Date Received 2021-05-28

Claims

What is Claimed is:
1. A helmet liner, comprising:
a liner body comprising an impact absorbing bottom layer, a slippery intermediate layer and a top fabric layer, the slippery intermediate layer overlying and being secured to the bottom layer, the top fabric layer overlying the intermediate layer, the top fabric layer having a perimeter and a central portion, the top fabric layer being secured on the perimeter leaving the central portion of the top fabric layer free to accommodate relative sliding movement of the intermediate layer.
2. The helmet liner of Claim 1, wherein the top fabric layer is stretchable, such that the top fabric layer accommodates increased sliding movement of the intermediate layer as the top fabric layer stretches.
4. The helmet liner of Claim 1, wherein the top fabric layer is being capable of serving as a loop portion of a hook and loop fastener and mating with a hook portion of the hook and loop fastener for the purpose of being anchored to an interior surface of a helmet.
5. The helmet liner of Claim 1, wherein the bottom layer is a polymer foam.
6. The helmet liner of Claim 1, wherein the intermediate layer is a polymer plastic.