CA1107902A - Protective helmet - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A helmet for the protection of sportsmen and/or workers in potentially hazardous occupations is disclosed. In one embodiment the helmet comprises a protective head shell and means to position the helmet on a users head in which the head shell has an outer section slidably connected to an inner section. The outer section is adapted to move relative to the inner section on impact with an object. In another embodiment the helmet comprises an outer shell and cushioning means on the inside of the inner shell. The cushioning means includes an inner shell that is spaced apart from the outer shell and which is adapted to move relative to the outer shells.
A plurality of projections is located between the two shells, each projection being integrally connected to one of the shells.
The projections are elongated and substantially rigid and are adapted to flex when subjected to compressive force.

Description

~ 1~ 7 ~ ~ 2 The present invention relates to a protective helmet and in p~rticular to a helmet for the protection of sportsmen and/or workers in potentially hazardous occupations.
Helmets having a rigid or substantially rigid outer shell are used by sportsmen and workers involved in activities in which there is a risk o~ injury to the head. For example, the use of such helmets may be compulsory or recommended protection in some ~ports e.g. footb&ll as played in North America, ice hockey/ auto racing and the like, or occupations e.g. the con-struction industry. In ice hockey potentially serious or e~enfatal inJuries can reæult ~rom, ~or example, a puck or a hoc~ey ætick striking the head o~ a player or a player striking his head on the boards around the hockey rink or o~ the goal posts. -~
Slmilarly in the conætructio~ industry such in~uries could re~ult -~rom falling ob~ectse e Ehape and design of protective helmets may vary accordlng to the intended use o~ the protective helmet. In general, however, conventional protective helmets have a rigid or substantially rigid outer shell, cushioning means, ~or example, ~oam padding and/or straps, and frequently means, for example, chin ~traps, to attach the helmet to the users head. In ~uch helmetæ a maJor amount of the energy absorbed by th~ helmet on impact with an ob~ect is by virtue of the presence of ~he cushioning means inside the helmet. ~nhile conYentional protective helmets af~crd signific~t p~otection for the head o~ the user, such helmets are capable of improvement especiall~ with respect to the amount Or energy that may ~e absorbed by ~he shell of the helmet.
Protective helmet~ having two shells are ~nown. For example, a protective helmet having internal and external shells interco~nected with VELCR0~ strips is disclosed in U~S. Patent * denotes trade mark ~ 2 3 413 656 of G. Vogliano and D. Beckman, issued December 3, 1968.
A helmet h~ing two shells and adapted for circulatlon of air between the shells for cooling is disclosed in Canadian Patent 693 175 Or R.~. Denton, issued August 25, 1964.
A protective helmet having two shells adapted for the absorption o~ energy on impact with an ob~ect has now been found.
Accordingl~ the present invention provides R pro-tective helmet comprising ~ protective he~d æhell of thermoplastic materlal and support means adapted to poRition said helmet on a users head~ said head shell ha~ing an inner section and an outer section, said outer section being superimposed on part of said inner section and being slidably connected to the inner section at at least two locations ~u~taposed to the edge of the outer sec~ion, the outer section being spaced apart from the ; inner section away from said locations, said outer section being adapted to move relative to the inner section on impact Or an ob~ect with said outer shell.
The present invention aiso provides a protective helme~
comprising:
(a) an outer shell;
(b) cushioning me~ns located on the inside o~ said outer shell, said cushionlng means including an inner shell spaced apart ~rom the ou~er shell and being adapted to move relative to the outer shell, (c) a plurality of pro~ections located between the inner shell and the outer shell, eaeh o~ said pro~ections being integrally connected to a base selected ~rom the group consisting - of (i) the outer shell, (ii~ the inner shell, and (iii) a base independent of said ~hells and which is loca~ed between said shells, æaid projectlons being elongated and substantially rigid and being adapted to flex when subjected to co~pressive ~orce, the pro-~ections having free ends that contact or are ~uxtaposed to P

~a~7~02 shell; and (d) æupport means adapted to position sa~d helmet on a users head.
~ he present invention is illustrated by the embodlments in the drawings in whlch:
Fig. 1 is a schematic representation of a protective helmet having two shells when viewed ~rom the rear;
Fig. 2 is a schematlc representation of a croæ~-section Or the helmet of Fig. 1 along the line 2-2.
Fig. 3 is a schematic representation Or a crosæ-section of a protect~ve helmet having inner and outer shells, the inner shell having a plurality of pro~ections;
Fig. 4 and Fig. ~ are schematic representations of ; embodiments of pro~ections in cross-sectio~.
F~g. 6 is a schematic representation o~ a plan view of an embodiment of the pro~ect~ons~ -; Fig. 7 is a schematic representation o~ a cross-section o~ the projection~ of Fig. 6.
Fig. 8 is a schematic representat~on o~ ~n alternate to the pro~ections shown in Fig~ 3, and Fig. 9 and Fig. 10 are schematic representations o~ a portion o~ & cross-section o~ the helmet o~ Fig. 3 be~ore and after impact, respectively, with an ob~ect.
: With reference to the dra~ings, Fig. 1 sh~ws a protective helmet, generally indicated by 10, having an outer shell 11 and an iDner shell 12. Ou~er shell 11 is superimposed o~ inner shell 12 and partially co~ers inner æhell 12. As shown in the drawing outer shell 11 haæ two elon~ated orifices 13 near the outer edge Or the shell. Plns 14 that are attached(not shown) to ~nner shell 12 pro~ect through elongated ori~ices 13 and slidably ~ttach outer shell 11 to inner shell 12.

~ '7~ ~ ~

The protective helmet of Flg. 1 ls shown in cross-section in Fig. 2. Outer shell 11 i5 ~uperimposed Gn inner shell 12, belng slidQbly attached to inner shell 12 by means of plns 14 through elongated orifices 13. Away from pins 14~ outer æhell 11 is spaced apart from inner shell 12, forming space 15 therebetween.
When outer shell 11 is struck by an obJect, outer shell 11 is forced towards inner shell 12. Air in space 15 acts as a cushion to absorb part of the energy of lmpact. In add~tion outer shell 11 moves relative to inner shell 12~ such movement - 10 being facilitated by pins 14 in elongated orifices 13, thereby absorbing an additionalpart of the energy of impact. Sub-sequently outer shell 11 will return to its original position.
Although not shown in Fig. 1 or Fig. 2 the protective helmet may have additional cushioning means e.g. foam pads and/or elastic straps located within the helmet ~or ~urther absorptio~
of energy. The helmet will normally also haYe support means, e.g. straps, adapted to posltion the helmet on a u~ers head. The helmet may also have attachment means, e.g. a chin ~trap~ adapted to retain the helmet on the users head.
~ig. 3 shows a protective helmet, general~y indicated by 20, hsving an outer shell ~1 and an inner shell 22. In the embodiment shown, inner shell 22 is attached to outer shell 21 by means of snap pro~ections 23 being pushed through snap orifices 24 in inner ~hell 22, snap orifice~ 24 being located at each end of inner shell 22. Snap pro~ections 23 are shown to be integxally attached to outer shell 21. It will~ however~ be understood by those skilled in the art that various other means m~y be u~ed to locate inner shell 22 within outer shell 21.
Inner shell 22 has a plurality o~ projections 25 on the sur~ace of inner shell 22 facing outer shell 21. Pro~ections 25 are integrally attached to lnner ~hell 22 and extend so that 7~3~)2 the ends thereo~ contact or are Juxtaposed to the in~er surface of outer shell 21. Pro~ections 25, which are elongated and taper towards their free end, are adapted to flex when sub~ected to a compressive force and revert to essentially their original shape when relieved of the effects of such a force. Such pro~ections are referred to hereln as being substantially rigid.
In the embodlment shown in Fig. 3 cushioning means 26, ln the form of foam pads, are located on the i~side, i.e.
the side which would contact a users head, of inner shell 22.
Cushioning means 26 are attached to innar shell 22 by means o~
~8pS 27 inserted through ori~ices 28 in inner she~l 22. Other means of attaching cushion~ng means 26 to inner hell 22 may be used, AS will be understood by those skilled in the art. In the embodiment of Fig~ 3, air vents 29 are shown to pass through cushioning means 26 and inner shell 22. ~ir vents 29 facili~ate the circulation o~ air, for cooling, between the inside o~ ~he helmet and the space 30 between inner shell 22 and outer shell 21.
External air ve~ts 31 connecting to space 30 may be pro~ided in .
outer shell 21.
Although ~ot shown in Fig~ 3 the protective helmet may have addit~onal cushioning means e.g. elastic straps, located within the helmet ~or further absorptlon o~ energy. The helmet preferably has 6upport means e.g. straps, adapted to position the helmet on a users head. ~he hel~et may also have attachment means e.g. a chin ~trapJ adapted ~o retain the helmet on the users head.
me protective helmet o~ Fig. 3 may have an outer shell 21 with an inner shell 22 ~uxtaposed to es~entially the entire inner sur~ac~ thereof. However in a preferred embodiment, especially for economics of construction of the helmet and to lighten the helmet, the inner shell 22 may be ~uxtaposed to only part of outer shell 21, such p~rt being in particular at those 7~

parts of the helmet that protect especially ~ulnerable portions o~ the user's head e.g. ~orehead, temples and the like. Inner shell 22 may there~ore be of an lrregular shape, depending on which parts of the head it i8 particularly deslrable to protect ln the light o~ the intended end u~e of the helmet. For example in a construction helmet ob~ects will tend to strlke the helmet on the top whereas in a hockey helmet greater emphasi~ may be necessary on the sides, front and back of the helmet. Other cushionin~ e.g. foam pads, may be located at some or all of tho~e parts where ~nner shell 22 is ~ot present.
Examples o~ pro~ections 25 are shown in ~i~. 4 and Fig. 5. In Fig. 4 the proJection 32 is essentially at right angles to the base 33 of the projection, base 33 being part of inner shell 22 of F~g. 3. Projection 32 iæ upright and tapers towards pro~ection end 34. In contrast pro~ection 35 o~ Flg. 4 is not at right angles to base 33 and ln the embodiment shown - pro~ection 35 is curved. In cross-section proJections 32 and 35 may be circular, square or another convenient shape, including elongated rectangular.
A pre~erred example o~ a pro~ection i8 shown in Fig. 6 and Fig. 7. The pro~ection, generally indicated by 36, ls com-prised o~ a plurality o~ protrusions 37, eight in the embodiment shown, arranged in a circle, the outæide sections 38 o~ protruslon~
37 being on the circumference of the circle. ProJectiDn 36 is shown in cross-section-in ~ig. 7 to be cylindrical with outside sectlons 38 thereo~ ~orming the edge o~ the cylinder. Protrusions 37 taper towards protrusion end 390 Pro~ection 36 resembles a cro~n in ge~eral æhape.
In the embodiment o~ the protective helmet shown in Fig. 3 the proJections 25 are shown to be integrally attached to inner shell 22. Alternatively some or all o~ pro~ectio~s 25 may ~ 7 ~ 2 be attached to outer shell 21 or each o~ outer shell 21 ~d inner shell 22 may have projection~ 25 attached thereto. In another embodiment both inner shell 22 and outer shell 21 may be ~ree of pro~ections 25; in such an embodiment proJections 25 are positioned on a sep~rate base and the base with its pro~ections is located between inner shell 22 and outer ~hell 21. Such pro-~ections may he on one or both sides of the base.
Another embodiment of the present lnvention is sho~ in Fig. 8. In Fig~ 8 nelther outer shell 21 nor ~nner shell 22 haæ
pro~ectlons. me pro~ections have been replaced with rib 40, rib 40 being substantially sinusoidal in shape. ~ib 4C may be used in con~unction with pro~ections 25 described previously.
The e~fect of an impact is shown ln Fig. 9 and Fig. 10.
Fi~ 9 represents a partial section of Fig. 3. Under ~he influence o~ an impact, shown generally by arrows 41 in Fig. 10, outer shell 21 is forced towards inner shell 22. Pro~ection~ 25 bend, or flex, under the compressive ~orce generated~ thereby becoming distorted from ~heir original shape and absorbing some o~ the energy. Subsequently pro~ections 25 return to essentially their orig~nal shape.
While the use o~ pro~ections has not been shown in the embodiment of Fig. 1 and ~ig. 2, one or bsth of outer shell 11 and ~nner ~hell 12 may have pro~ections ~ntegrally attached thereto.
~lternatively pro~ections on a separate base may be placed in ~pace ~5. The use o~ pro~ections in the embodiment o~ Fig. 1 and Fig. 2 must be selective so as not to significantly hinder - the relative movement o~ outer shell 11 with respect to inner shell 12 on impact of an ob~ect with outer shell 11.
The protective helm~ts of the present i~vention may be ~abricated from a var~ety of thermoplastic and thermoset poly-mers, the particular polymer depending on in particular the 1~(''7~3~2 intended end-use of the helmet ~nd the required properties of the helmet; thermoplastlc polymers are preferably used to rabricate the pro~ections. The outer and lnner shells of the protective helmet may be fabricated ~rom the same or different polymers, the location and type Or pro~ections used, and the properties thereo~, being factors in the selection of the polymers for the shells. Examples of polymeræ are poly-O--olefins e.g. polypro-pylene, homopolymers of ethylene and copolymers of ethylene and other o~-olefins e.g. butene~l and vinyl acetate, and mixtures thereo~; polyamide~, especially polyhexameth~-lene adipamide and blends thereof ~ith a compatible elastomeric or rubber material, polycarbonate, acrylonitrile/butadiene/styrene polymers; polyvinyl chloride, cellulo~e acetobutyrate; polybutylene terephthalate, polyoxymethylene polymers; polyester or epoxy polymers rein~orced with glass or KEVIAR* aramid ~ibre~, and the like. In preferred embodiments the outer shell i8 fabricated ~rom a polyethylene, or a blend o~ polyethylenes, havi~g a density of at least 0.950 and ~ melt index ln the range 1 to 12, especially 4 to 63 melt index being mea~ured b~ the method of ASTM D-1238 (~ondition E), and the inner ~hell iæ fabr~cated from a similar p~lyethylene or a blend of 50-70%, by weight, o~ such a p~lyethy-lene and 30-5~ by weight, of an ethylene/vinyl acetate copolymer having 15 to 20% o~ vinyl acetate ccmonomer. Preferably the polymer-is æelected æo that ~nJection moulding techniques may be used in the manufacture of the helmet.
ProJections 36 shown in ~ig. 6 and Fig. 7 may be obtained using in~ection mouldi~g technique~. In inJection moulding, e~ector pins are used to facilitate removal of the ~n~ection moulded article from the mould. While relatlvely few pins are normally used in an in~ection moulding process, a plurality of e~ector pins may be utilized to obtain pro~ection~

* denotes trade mark ~ 1~ 7 ~ 0 ~

36. In order to do so, the e~ector pin may be machined to the shape required to obtain protrusions 37 o~ pro~ection 36. A
plurality of e~ector pin~ ~o machlned may be used in the formation of a plurality of proJections 36 on the article that is inJection moulded.
The size and number of the pro~ections 2~ of the helmet of Fig. 3 will depend on the particular thermoplastic material and on the required properties o~ the helmet. In embodiments the pro~ections illustrated in Fig. 5 may have a height of 0.5-1.5 cm and a thickness of 0.050-0.150 cm, whereas the proJections of Fig. 6 and Flg. 7 ma~ have a height of 0.25-0.75 cm. Other embodiments are exemplifled hereina~ter.
The number o~ pro~ections per unit area may vary dependi~g on the location within the protectiue helmet and the desired properties of the helmet. Embodiments are exempli~ied hereinafter.
In an embodiment the pro~ections o~ Fig. 6 and Fig. 7 are allgned so that the ~entres o~ the pro~ections are at the corn~rs Q~
squares. Additlonal pro~ections may be placed at the centres of such squares. The diameter of the circles formed by the pro~ectlons shown in Fig. 6 and Fig. 7 may be important in the location of the pro~ections. Examples of such diameters are gi~en hereinafter.
The present i~vention i~ illustrated by the ~ollowing exa~ples.
EXAMPLE I
The procedure used to test helmets in this ~xample `~ ~as th~t specl~ied in Canadian Standards Association Standard X 26~ 1975 "~ockey Helmetsn. In summary the procedure ~nvolves a Brinell impact test in ~Jhich a ~irch striker block we~ghing 4.5~ kg ralls freely from a height o~ 61 cm to strike a teæt sample (helmet) located on a polyurethane headform. me ~orce transmitted by the test sample i8 determined by means of the impres-"sion made in an aluminum bar of a Brinell penetrator assembly.

~ 7 ~ ~

Using the above procedure a commercial hockey helmet was tested~ the impact of the ætriker block being on the top o~ the helmet. The helmet had a polycarbonate shell o~ thlc~ness o~ 0.25 cm and apolyurethane roam pad o~ a thick~ess o~ 1.76 cm at the top o~ the helmet. The force transmitted was 4~9 k Newtons.
When the foam pad was removed and the shell alone was tested the ~orce transmitted was 14.8 k Newtons.
Cushlon p~d~, hereinafter referred to aæ pi~ cushion~, having pro~ections of the type shown in Fig. 6 and Fig. 7 were manu~actured by in~ection moulding techniques. The polymer uæed was a blend of 67 parts o~ SC1AIR* 29Q7 polyeth~lene, an ethylens homopolymer of a denslty of o.960 g/cm3 and a melt index o~ 5, and 33 parts of ALATH0~* 3170, an ethylene/vin~l aceta~e copolymer containing 18% by weight of Y~nyl acetate and having a melt index of 2.5 and a dengity of 0.940 g/cm3. The pin cushions either had "long teeth" i~8~ proJections of a length of 0.475 cm and a thickness at their base of Orl cm, or "short ~eeth" i.e.
pro~ections of a length o~ 0.30 cm and a thicknes~ at their base of 0.1 cm. In each case, the pin cushion~ were approxlmately 7.5 cm square with the pro~ections aligned in row~ ~nd spaced apart at 1 cm centres. The d~ameter of the circle o~ pro~ections was o.6 cm~ The thi~kness o~ the bas~ of the pin cushion was 0.150 cm.
A pin cushion was placed in the centre of th~ shell of ~he hockey helmet i.e. the shell without foam pads~ r~ferred to above and a pad of a foamed polyurethane o~ den~ity of 0.115 was placea under the pin cushion thereb~ producing a con~tructlo~
of shell/pin cushion/pad. The resultant co~struction was then tested and the results obtained were as follow~:

* denotes trade mark 1~79~2 Run Pln Cushion Pad Thicknes~Force Transmltted ~type) ~ ~k Newto 1 long - 12.4

2 long 0.45 11.1

3 long 0.88 6.4

4 ~ong 1.33 4.7 long~* o.45 9.1 ** two pin cushions placed face-to-face w~re u~ed ~he above procedure wa~ repeated ~ith a commercially avallable hockey helmet manufactured by a di~erent ~anufacturer.
This commercial helmet also has a polycarbonate shell o~ a thic -ness of 0.25 cm but the foamRd polyuretha~e pad wa8 1.4 cm in - thickness. me force tr~nsmitted by the helmet wa8 4.8 k Newton~.
When the shell alone wa8 tested the ~orc2 tra~smitted wa~ 14~8 k Newt~ns.
T~iæ helmet ~as also tested using the pin cushions ~ith and without polyurethane pads. The results obtained were a~
~ollows:
Run P~n ~ushion Pad ThicknesæForce Transmitted (t~pe) (cm) ~~ ~ewton~J~
6 ~hort - 10.3 7 lon~ _ 9.4 -. 8 short 0,~5 6.7 9 long 0.45 6.4 short 0.88 5~1 11 long ~.88 4.9 12 long** - 7.7 ** ~wo pin cushions placed ~ace-to face were u~ed.
EXAMPLE II
Pin cushions with short teeth, a~ described in Example I, were m2nu~actured from (a) SCLAIR 2907 polyethylene, (b) a blend o~ SCLAIR 2907 polyeth~lene (2 part~) and ALAT~0~

:~o~

3170 ethylene/vinyl acetate copol~mer (1 part) and (c) a blend of SCLAIR 2~07 polyethylene (1 part) and ALATHON 3170 copolymer (1 psrt). The pin cushions wera tested by dropplng a 4.54 kg weight having a rounded end from a height of 61 cm onto a test sample. The test sample had the following constructlon: a o.63 cm thick steel plate measuring 15.24 cm by 15.24 cm/0.63 cm o~ a ~oamed material/an area of pin cushion with the ~eeth facing away from thc foamed material/ a 0.23 cm thick sheet oP high density polyethylene. The force transmitted on impact o~ the weight was measured using a Brinell penetrator assembly.
In a series of exper~ments the tot~l area o~ the pin cushions was v~riedg the centre Or the Prea of the pin cushion~
be~ng a~ the poin~ of impact of the weight.
The results ob~ained, expressed a~ ~orce transmitted in k Newtons~ were as follo~s:
Area of Pol~mer Pin Cushion (cm~) ~~~ AIATHON 3170(1:1) Alathon 3170(2:1) 29 6.5 6.9 6.7 (8.9)*
20 58 6.o 5.9 5.~ (8-o) 87 5.8 6.o 5.5 (7-8) 131 _ 6~9 6.8 (8~5) * the figures ~n brackets are comparative ~igures ror test samples in which the ~oamed matsrial was omltted.
The above procedure wa~ repeated wlth pin cu~hions that had pro~ections loc~ted bet~ee~ the rows in addition to the p~oJections ~ligned in rows ~s in the pin cushion~ o~
Ex&mple I. me additional pro~ections were identical to those of Example I except that the diameter o~ the clrcle o~ the additional pro~ections ~as 0.5 cm.
The results obtained were as follows:

11~79¢~2 Area o~ Polsnner Pin CushlonSCLAXR 2907 SCLAIR 2907/ SZ~ 29~77-(cm2) ALAT~ON 3170(1:1) ALAl~ION 3170(2:1) 29 6.1 6.8 6.6 58 4.9 5.2 5.3 87 4.8 5.2 5.2 131 6.o 7.0 EXAMPIE III
A pin cushion with short teeth, as described in Example I, a~d manu~ctured f`rom SCLAIR 2907 po~yeth;s~lene was tested by dropping a 0.80 k~s weight from a height of 127 cm onto a test sam~?le. ~he test sample had the following constructio~
a o.63 cm steel plate/a 0.23 cm sheet of high density polyethy-lene/pin cushion with pro~ectlons ~acing the polyet~ylene sheet.
me area of the pin cushion wa~ 58 cm2.
me test sample was te~ted at intervalæ o~ sixt~
seconds, ~he ~eæultæ obtained were, in æe~uen~e, as ~ollows:
3.4, 3.5, 3.5, 302 and 3.6 k Newl;ons.
E~ I~1 Pin cuæhions were manufactured rrom either SCLAIR 2907 or the blend o~ SCLAIR 2907/ALATEIQN 3170 referred to in E~cample I.
~he pin cushions were teæted using the procedure o~ Example III.
The results were as follo~:
Run Polymer P~n Cushion Force Tran~mitted (type) (k Newton~
1 SCLAIR 2907 short 3.3 2 SCLAIR 2907 lon~ 3.2 3 SCLAIR 2907/AhAT~ON 3170short 3.0 4 SCIAI~ 2907/ALATHON 3170long 3.0 3~ EXAUoeIE V
Pin cushio~8 manu~actured ~rom a number o~ polym~rs were tested using the procedure o~ Example III. me results were as follows: (all samples had short teeth).

1 1~ 7 ~ 2 Run Polymer** Force Transmitted ~ (k Newtons) l A 2.8*
2` B 3.1 3 C 3.3 E 3.3 6 F 3.1 * sample was warped ** A ...... SCLAIR 2709 polyeth~lene, a polyethylene ha~ing a density o~ 0.950 and a melt lndex o~ 14.5 ~ .
B ...... SCLA B 2507 polyethylene, a polyethylene ha~ing a denslty o~ 0.940 and a melt index o~ ~.0 C ...... SCLAIR 2706 B polyethylene, a polyethylene ha~ing a dens~ty of 0.950 and a melt index o~ o.65 - D ~o~ SCLAIR 8405 polyethylene, a polyethylene haYing a densi~y of 0.937 and a melt index o~ 2.7 E ...... SCLAIR 8107 polyethylene, a polyethylene having a de~slty o~ 0.924 a~d a melt index o~ 5.1 F ...... ALATEON 3170 ethylene/~inyl acetate copolymer. :
.-`

.

Claims (15)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A protective helmet comprising:
(a) an outer shell;
(b) cushioning means located on the inside of said outer shell, said cushioning means including an inner shell spaced apart from the outer shell and being adapted to move relative to the outer shell;
(c) a plurality of projections located between the inner shell and the outer shell, each of said projections being inte-grally connected to a base selected from the group consisting of at least one of (i) the outer shell, (ii) the inner shell, and (iii) a base independent of said shells and which is located between said shells, said projections being elongated, substantially rigid and being adapted to flex when subjected to compressive force and to revert to essentially their original shape when relieved of the effects of such a force, the projec-tions having free ends that contact or are juxtaposed to a shell; and (d) support means adapted to position said helmet on a users head.

2. The helmet of Claim 1 in which there is a chin strap adapted to retain the helmet on a users head.

3. The helmet of Claim 2 in which there is addi-tional cushioning means selected from the group consisting of foam pads and elastic straps, and mixtures thereof.

4. The helmet of any one of Claim 1, Claim 2 and Claim 3 in which the projections are integrally connected to the outer shell.

5. The helmet of any one of Claim 1, Claim 2 and Claim 3 in which the projections are integrally connected to the inner shell.

6. The helmet of any one of Claim 1, Claim 2 and Claim 3 in which the projections are integrally connected to a base independent of said shells and which is located between said shells.

7. The helmet of any one of Claim 1, Claim 2 and Claim 3 in which the outer shell and the inner shell are each manufactured from material selected from the group consisting of poly- .alpha.-olefins, polyamides, polycarbonate, acrylonitrile/
butadiene/styrene polymers, polyvinyl chloride, cellulose acetobutyrate, polybutylene terephthalate, polyoxymethylene polymers, reinforced polyester polymers and reinforced epoxy polymers, said reinforced polymers being reinforced with glass or aramid fibres.

8. The helmet of any one of Claim 1, Claim 2 and Claim 3 in which the projections are integrally connected to the inner shell and said outer shell is manufactured from a material selected from the group consisting of poly-.alpha.-olefin, polyamide and polycarbonate.

9. The helmet of Claim 2 in which the projections are integrally connected to a base selected from the group consisting of the outer shell and the inner shell and said outer shell and said inner shell are each fabricated from a poly-.alpha.-olefin.

10. The helmet of Claim 9 in which said poly-.alpha.-olefin is polyethylene having a density of at least 0.950 and a melt index in the range 1-12.

11. The helmet of Claim 2 in which the projections are integrally connected to the inner shell and said inner shell is fabricated from a material selected from the group consisting of (a) polyethylene having a density of at least 0.950 and a melt index in the range 1-12 and (b) a blend of the polyethylene of (a) with an ethylene/vinyl acetate copolymer having 15-20% of vinyl acetate comonomer.

12. The helmet of Claim 10 or Claim 11 in which said melt index is in the range 4-6.

13. The helmet of any one of Claim 9, Claim 10 and Claim 11 in which the projections have a height of 0.5-1.5 cm.

14. The helmet of any one of Claim 9, Claim 10 and Claim 11 in which the projections are located on peri-pheries of circles.

15. The helmet of any one of Claim 9, Claim 10 and Claim 11 in which the projections are located on peripher-ies of circles, said circles being aligned so that the centres thereof are located at the corners of squares.