IMPROVEMENTS IN PROTECTIVE HELMETS

Abstract: A protective helmet (60) having a circumferential support (61) mounting a helmet shell (62) and visor guides (81), a visor (80) movable within the shell (62) between lowered and raised positions and guided by the visor guides (81), a head harness (75) carried by the support (61) and ear defenders (90, 91) movably mounted at opposite sides of the helmet. The helmet has a removable air filter unit (71) which is fitted in an interference fit within an air inlet cavity of the helmet.

Description: Improvements in Protective Helmets This invention relates to a protective helmet used by operatives in industrial environments, e.g. in the mining or quarrying industries. The invention also relates to a filter unit for such a protective helmet. A known protective helmet, disclosed in US-A-5283914, is provided with a retractable visor, a fan for providing filtered airflow through ducting within the shell to regions in front of the wearer's face and ear defenders movably mounted at each side of the helmet. The present invention seeks to provide improvements to the known designs of protective helmets. According to one aspect of the present invention there is provided a helmet filter unit intended to be received in an air inlet cavity of a helmet defined by cavity side walls, the filter unit comprising a support frame having frame side walls and defining at least one air inlet and flexible filter material extending across the air inlet(s) for filtering air passing through the air inlet(s), characterised in that the filter material is secured to outer surfaces of the frame side walls and in that in use the filter unit is intended to be received in an interference fit in the air inlet cavity with the filter material sandwiched between, so as to provide an air seal between, the cavity side walls and the frame side walls. According to another aspect of the present invention there is provided a protective helmet having support means at each side of the helmet and ear defenders carried by the support means and movable between inner and outer positions, each support means comprising a pair of wire supports pivotable about spaced apart parallel pivot axes and each having an offset portion between its ends, each ear defender being carried between the offset portions of the associated pair of wire supports, the offset portions moving through dead centre positions as the wire supports pivot in opposite directions about their respective pivot axes during movement of the ear defender from either one to the other of said inner and outer positions, the support means further comprising resilient means acting on the offset portions of each pair of wire supports to urge the associated ear defender away from the dead centre positions towards one or the other of its inner and outer positions. Preferably the offset portions, when in their dead centre positions, are spaced a maximum distance apart from each other which is greater than the separation of the pivot axes of the wire supports. In this case the resilient means act to urge the offset portions towards each other and resist movement of the wire supports through over centre positions. Conveniently the resilient means comprise metallic spring clips positioned outwardly of the offset portions. According to another aspect of the present invention there is provided a protective helmet comprising a shell and a harness for supporting the helmet on a wearer's head, characterised in that the helmet further comprises a circumferential support on which the shell is mounted and which carries the harness so that it is spaced from the inside of the shell. Preferably the helmet also comprises a retractable visor and visor guides at the sides of the helmet for guiding the visor during movement of the latter between a lowered position and a raised position retracted within the shell, the visor being movable between the harness and the shell on movement of the visor between its lowered and raised positions. Conveniently the helmet has ducting spaced inwardly from the shell for supplying filtered air to a region at the front of the helmet. If the helmet has a retractable visor, the ducting is positioned so as not to interfere with the visor on movement of the latter between its lowered and raised positions. Preferably, the ducting is provided in a ducting member connected to a rear part of the circumferential support, provided with at least one air inlet, and a front part of the circumferential support, provided with at least one air outlet. The helmet suitably also comprises air filtering means including an electrically operable motor for supplying filtered air inside the helmet. If a visor is provided, switch means for controlling operation of the motor, may be arranged to be actuated on movement of the visor between its lowered and raised positions. An embodiment of the invention will now be described, by way of example only, with particular reference to the accompanying drawings, in which: Figure 1 is a side view, partly in section, of a known protective helmet on a wearer's head; Figure 2 is an interior view of the protective helmet shown in Figure 1; Figure 3 is a view from the front of a protective helmet, according to the invention, on a wearer's head, showing ear defenders on opposite sides of the helmet in inner and outer positions, respectively; Figure 4 is a side view of the helmet shown in Figure 3; Figure 5 is a sectional view through part of the helmet shown in Figures 3 and 4; Figure 6 is a partly sectioned view of an ear defender of the helmet shown in Figures 3 to 5; and Figure 7 is an end view, on an enlarged scale, of a replaceable helmet filter unit for use in the helmet shown in Figures 3 to 6. Figures 1 and 2 show a known protective helmet 1, of the type shown in US-A-5283914, in the form of a powered respirator helmet in position on a wearer's head 3, the helmet comprising a protective shell 2 having a rear part 4, a crown 6, a front part 8 and sides 10. A head harness (not shown) is provided within the shell 2 for comfortably seating the helmet on the wearer's head 3. An inner skin 12 extends from the rear part 4 to the front part 8 and defines in the occipital region an air inlet 14 across which there is provided a filter 16 of suitable fibrous material. The filter is clipped into a holder 13 and can be easily removed and replaced. A further inner skin which comprises part of the shell 4, 6, 8 extends through 4 , 6 and downwards through 8 terminating in a plurality of outlets 20 in the form of slots. An air duct 22 is thus defined within the shell 2 between its inner surface and the skins 12 and 4, 6 and 8. A front cover 9 is fixed to the shell 2 to provide a smooth profile to the helmet exterior and, with the front part of the protective shell, provides a space 42 into which the visor 30 may retract. An air mover in the form of two battery-powered fans 24 is located within the duct 22 on sound-absorbing mounts 26 rearwards of the crown 6 of the shell 2. The power for the fans 24 is conveniently provided by a body mounted battery pack (not shown) which is of such capacity as additionally to power a lamp (not shown) releasably fixable to the front part 9 on a bracket 29 provided for that purpose. A visor 30 comprising a carrier 32 which is releasably fixed to a transparent window 34 is slidably and pivotally mounted on supports 38 fixed to the sides of the helmet shell 2, with bushes 39 attached to the visor carrier 32. The supports 38 have curved slots within which the bushes are adapted to slide. The visor is retractable within a space 42 defined between part 8 of the shell 2 and the inside wall of the outer cover 9. The visor 30 has a stop for abutting a cut¬ off switch (not shown) such that when the visor is fully extended in a lowered position in front of the wearer's face, the power to the fan 24 is initiated. Additionally, in this position, the visor is sealed against the inner face of the outer cover 9 by a sealing strip 21. The visor may alternatively seal against the outer face of the shell 8 along its lower edge. A limited pivoting motion about the lower bush 39 may be provided to enable the lower part of the visor to move closer to the wearer's face, and is achieved by a small recess in the slot in the support 38 into which the upper bush may move. In its operative position shown in Figure 1, the visor 30 in conjunction with cheek plates 52 and ear defenders 50 on the sides of the shell 2 gives panoramic protection for the front and sides of the wearer's face. Figures 3 to 7 show a protective helmet 60 according to the present invention which is similar in many respects to the known helmet 1 shown in Figure 1 and 2. In the following description the main differences between the helmets 1 and 60 will be described. The helmet 60 has a main chassis-like circumferential plastics support 61 which carries or mounts the main parts of the helmet 60. In particular, a protective shell 62 is mounted, e.g. adhered, in an upwardly open socket portion 61c of the support 61. A flexible ducting member 63 positioned inside, and spaced from, the shell 62 connects a rear portion 61a of the support to a front portion 61b of the support. The ducting member 63 has a single main inlet chamber 64 connected to an air inlet cavity 65 formed in the rear portion 61a and four outlet ducts 66 (only one of which is shown in Figure 4) connected to a plurality of air outlets 67, 68 in the front portion 61b. The inlet chamber 64 opens into two intermediate ducts 69, in each of which an electric fan 70 is received, and each intermediate duct 69 branches into two of said outlet ducts 66. A removable air filter unit 71 is received in an interference fit in the air inlet cavity 65 and comprises an elongate, e.g. curved or arcuate, channel section plastics support 72 having a base 72a with apertures 72b therein, flanged spaced apart side walls 72c and 72d and flanged end walls 72e and 72f. A pocket-like flexible, cloth- or fabric-like filter medium 73 is carried by the support 72, with the open mouth-like end of the pocket-like filter medium being attached, e.g. adhered, to the outer surfaces of the side and end walls of the plastics support 72. The filter medium is thus positioned across the air inlets provided by the apertures 72b and defined between the side walls of the support. When the air filter unit 71 is in position (as shown in Figure 5), parts of the flexible filter medium 73 are sandwiched between the walls of the air inlet cavity 65 and the side and end walls of the plastics support 72. The spaced apart side walls of the support 72 can be resiliently urged slightly towards each other and, when the filter 71 is in position, these side walls may be slightly resiliently compressed towards each other by the walls of the air inlet 65 so that the sandwiched filter medium is resiliently urged or pressed into air sealing contact with the walls of the air inlet 65 whilst at the same time retaining the air filter in position in an interference fit within the air inlet cavity. Although it is preferred that the support is of channel-section, the apertured base 72a could be dispensed with provided that the side walls of the support are sufficiently rigid to remain spaced apart and provide an air inlet passage between the side walls. A harness arrangement, schematically shown by dashed lines 75, is detachably carried by the support 61 and is positioned inwardly of the ducting member 63. Suitably the harness comprises a plastics headband, adjustable to suit the wearer's head size, and webbing attached thereto which in use is intended to sit on the crown of the wearer's head. The harness has a number of connecting members (not shown) for detachable connection to a number of connection sockets 76 on the support 61. A bulbous, e.g. part-spherical, visor 80 is movable from a lowered position (shown in Figures 3 and 4) in front of a wearer's face to a raised position (not shown) retracted within the helmet. The visor 80 is movably guided by guide members 81 carried by the support 61 at each side of the helmet immediately above ear defenders 90 and 91 (to be described in greater detail hereafter) . Each guide member has a curved, e.g. arcuate, slot 82 and bushes 83 and 84, connected to wing portions of the visor, are slidably received in this slot 82 during movement of the visor between it raised and lowered positions. It will be appreciated that the visor 80 is moved inside the shell 62 in the space between the shell and the ducting member 63. Unlike many helmets, the harness 75 is not carried by the shell 62 but instead is carried by the support 61. Thus the harness 75 does not interfere with the visor during movement of the latter between its raised and lowered positions. By arranging the guide members 81 relatively far back on the helmet, i.e. above the ear defenders about half way between the front and back of the helmet, the bulbous visor 80 can be pivoted fully within the helmet shell whilst remaining in the space defined between the inside of the shell and the ducting member 63. At the front of the helmet, on the shell 62, a light mounting, generally designated 85, is provided for detachably mounting a lamp (not shown) to the helmet. Although not shown, a belt-carried battery pack with a length of cable is connected to the lamp and, when the lamp is fitted to the helmet, the cable is clipped to the helmet by a cable clamp 86. Various electrical leads are shown in Figure 4 extending between the light mounting 85, the electric fans 70 and a switch 87 mounted to one of the guide members 81. The switch 86 has a switch arm 88 moved by the bush 84 for controlling operation of the fans 70 and the helmet-mounted lamp which are designed to be turned on as the visor is moved into its lowered position and to be turned off as the visor is moved upwardly out of its lowered position. The position of the arm 88 after the visor 80 has been raised from its lowered position is shown in dashed lines in Figure 4. The ear defenders 90 and 91 are mounted at each side of the helmet for movement between an outer position (see ear defender 90) and an inner position (see ear defender 91). Since both ear defenders and their mounting to the helmet are similar, only one ear defender 90 and its mounting will be described in detail hereinafter. The ear defender 90 comprises a hollow plastics casing 92 (see Figure 6) in which sound absorbing material 93, e.g. plastics foam material, is received. A flexible resilient pad 94 intended to be pressed against a wearer's head around the ear is fixed to the front of the ear defender about an opening 95 in the casing 92. The ear defender 90 is mounted to the helmet by a pair of wire supports 96 and 97 each having axially aligned opposite end portions 96a and 96b (97a and 97b) and an offset portion 96c (97c) between its end portions. Each offset portion 96c, 97c has an inwardly turned connecting portion 96d, 97d, respectively. The end portions of the wire supports 96 and 97 are pivotally received in rear and front socket members 98 and 99, respectively. The front socket member 99 is carried by a downwardly extending portion 100 of the support 61 and the rear socket member 98 is carried by a bracket 101 depending downwardly from the support 61. Each socket member 98, 99 has upper and lower sockets, the two upper sockets being axially aligned and receiving the end portions 96a and 96b of the wire support 96 and the two lower sockets being axially aligned and receiving the end portions 97a and 97b of the wire support 97. In this manner the two wire supports are pivotally movable about parallel axes defined by the aligned end portions 96a and 96b and the aligned end portions 97a and 97b. The inwardly turned portions 96d and 97d of the wire supports are received in upper and lower sockets 104 and 105, respectively, formed in the casing 92 and are retained in these sockets by spring clips 106 and 107, respectively. Each spring clip is preferably a metallic spring clip which has a mounting portion 108 received between two upwardly and inwardly open slots formed in the casing 92 and which is releasably locked in position by a stud on the casing which enters a locating hole in the mounting portion 108 and a spring portion 109 positioned outside the offset portion 96c (97c) of the wire support. The portions 96d and 97d and the sockets 104 and 105 are aligned on an axis 106. In the outer position of the ear defender, the offset portions 96c and 97c of the wire supports are not coplanar but are disposed in planes at an angle, e.g. of about 125°, to each other. The ear defender 90 can be moved inwards from its outer position by manually pushing a gripping member 110 of the ear defender in the direction A (see Figure 3) so that the wire supports 96 and 97 pivot in opposite directions and the offset positions 96c and 97c are moved towards "dead centre" positions in which they occupy a plane containing the pivot axes of the two wire supports. During this movement towards the dead centre position of the offset portions, the inwardly turned portions 96d and 97d move outwardly in the sockets 104 and 105, respectively, and resiliently urge the spring portions 109 of the spring clips 106 and 107 outwardly. The spring clips 106 and 107 thus provide a resilient force acting to resist movement of the ear defender 90 in the direction A. As the offset portions move through their "dead centre" positions, in which the inwardly turned portions 96d and 97d are at a maximum spacing from each other, the inwardly turned portions move back towards each other within the sockets 104 and 105. The resilient or spring force provided by the spring clips 106 and 107 now assists inward movement of the ear defender towards an innermost position of the latter. In practice, in use of the helmet, the flexible resilient pad 94 contacts the wearer's head before the ear defender reaches its innermost position so that the spring clips 106, 107 provide a resilient pressing force pushing the ear defender against the wearer's head around the ear of the wearer's head. In this position, the offset portions 96e and 97e are disposed at an angle of typically about 150° to each other, as opposed to an angle of about 135° when the ear defender is in its innermost position (e.g. when its inward movement is not limited by contacting a wearer's head) . The ear defender 90 can be moved back to its outer position by pulling the gripping member 110 against the resilient force provided by the spring clips 106, 107 so that the wire supports 96, 97 pivot in opposite directions. As the offset portions 96c, 97c pass through the "dead centre" position, the resilient force of the spring clips urge the ear defender 90 back to its outer position. Thus the ear defender 90 moves into or towards its inner or outer positions with a "snap action" as the offset portions move through their dead centre positions. The ear defender 90 is able to pivot slightly about the axis 106 and about the pivot axes of the wire supports so as to provide a "floating" mounting. This enables the ear defender 90 to orientate itself properly against a wearer's head in use. The novel concepts covered by the present invention over, for example, the helmet shown in US-A-5283914, are: 1. The mounting of the ear defenders to the sides of the helmet providing reliable snap-action mountings for moving the ear defenders between inner and outer positions. 2. The provision of a chassis-like circumferential support which carries the main elements of the helmet such as the helmet shell and a head harness. If a retractable visor is provided, mounting means for movably supporting and guiding the visor as it is raised and lowered are also carried by the support. By supporting the head harness from the circumferential support instead of from the helmet shell, a clearance space is provided immediately inside the helmet shell into which the visor, if provided, can be retracted. 3. The provision of arcuate visor guides at the sides of the helmet so that the turning axis of the visor in moving between its lowered and raised positions is set relatively far back, substantially mid-way between the front and back of the helmet. This allows the bulbous or approximately part-spherical visor to closely follow the contour of the shell as it is moved inside the shell on movement between its raised and lowered positions. 4. The provision of a replaceable filter unit which uses material of the filter medium to provide an air seal with walls of an air inlet chamber of the helmet.

Claims: CLAIMS 1. A helmet filter unit (71) intended to be received in an air inlet cavity (65) of a helmet defined by cavity side walls, the filter unit (71) comprising a support frame (72) having frame side walls 72c-72f and defining at least one air inlet (72b) and flexible filter material (73) extending across the air inlet(s) (72b) for filtering air passing through the air inlet(s), characterised in that the filter material (73) is secured to outer surfaces of the frame side walls and in that in use the filter unit (71) is intended to be received in an interference fit in the air inlet cavity (65) with the filter material (75) sandwiched between, so as to provide an air seal between, the cavity side walls and the frame side walls (72c-72f). 2. A helmet filter unit according to claim 1, characterised in that the frame side walls are flanged. 3. A helmet filter unit according to claim 1 or 2, characterised in that the support frame is of elongate, e.g. arcuate elongate, generally channel section, shape, the frame side walls providing spaced apart, e.g. arcuate, sides and opposite ends. 4. A helmet filter according to any of claims 1 to 3, characterised in that the support frame has an apertured bottom wall. 5. A helmet filter according to any of claims 1 to 4, characterised in that said side walls are resiliently deflectable towards each other. 6. A protective helmet having an air inlet cavity defined by cavity side walls and fitted with a removable air filter unit as claimed in any of claims 1 to 5, the flexible filter material being sandwiched between the cavity side walls and the frame side walls to provide an air seal between these walls. 7. A protective helmet (60) having support means at each side of the helmet and ear defenders (90) carried by the support means and movable between inner and outer positions, characterised in that each support means comprises a pair of wire supports (96,97) pivotable about spaced apart parallel pivot axes and each having an offset portion (96c,97c) between its ends (96a,97a), each ear defender (90) being carried between the offset portions of the associated pair of wire supports, the offset portions (96c,97c) moving through dead centre positions as the wire supports (96,97) pivot in opposite directions about their respective pivot axes during movement of the ear defender (90) from either one to the other of said inner and outer positions, and in that the support means further comprises resilient means (106,107) acting on the offset portions (96c,97c) of each pair of wire supports (96,97) to urge the associated ear defender (90) away from the dead centre positions towards one or the other of its inner and outer positions. 8. A protective helmet (60) according to claim 7, characterised in that the offset portions (96c,97c), when in their dead centre positions, are spaced a maximum distance apart from each other which is greater than the separation of the pivot axes of the wire supports. 9. A protective helmet (60) according to claim 8, characterised in that the resilient means (106,107) act to urge the offset portions (96c,97c) towards each other and resist movement of the wire supports (96,97) through over centre positions. 10. A protective helmet according to claim 8 or 9, characterised in that the resilient means comprise metallic spring clips (106,107) positioned outwardly of the offset portions (96c,97c) . 11. A protective helmet (60) comprising a shell (62), and a harness (75) for supporting the helmet on a wearer's head, characterised in that the helmet further comprises a circumferential support (61) on which the shell (62) is mounted and which carries the harness (75) so that it is spaced from the inside of the shell. 12. A protective helmet according to claim 11, characterised in that it further comprises a retractable visor (80) and visor mounting means (81) carried by said circumferential support (61), the visor (80) being movable between the harness (75) and the shell (62) on movement of the visor (80) between its lowered and raised positions. 13. A protective helmet according to claim 12, characterised in that ducting (63) is spaced inwardly from the shell (62) for supplying filtered air to a region at the front of the helmet, the ducting (63) being positioned so as not to interfere with the visor (80) on movement of the latter between its lowered and raised positions. 14. A protective helmet according to claim 13, characterised in that the ducting (63) is provided in a ducting member connected to a rear part of the circumferential support (61), provided with at least one air inlet (65), and a front part of the circumferential support (61), provided with at least one air outlet (68).

Inventors: BULBROOK LEE GEORGE, FORREST JACQUES WILLIAM, PATON COLIN ANDREW, BULBROOK, LEE, GEORGE, FORREST, JACQUES, WILLIAM, PATON, COLIN, ANDREW
Applicants: BULBROOK LEE GEORGE, FORREST JACQUES WILLIAM, PATON COLIN ANDREW, THETFORD MOULDED PROD LTD, BULBROOK, LEE, GEORGE, FORREST, JACQUES, WILLIAM, PATON, COLIN, ANDREW, THETFORD MOULDED PRODUCTS LIMITED
Application year: 1996
Main classification: A42B3
IPC codes: A42B3, A62B18