Helmets

Abstract: A helmet (10) has a visor (12) mounted on pivot posts (18) fixed to the helmet. A visor driving and latching mechanism (24) acts both to allow the wearer to move the visor (12) between its lowered and raised positions and also to hold the visor in either position. The mechanism (24) has an operating lever (22) which is pivoted to the visor (12) at a point (30) spaced from the pivot post (18). The operating lever (22) has a slightly elongated aperture (28) which receives the pivot posts (18), and a hollowed out portion (32) which receives a cam (38) fixed in relation to the pivot post (18). The operating lever (22) has a first tooth (36) which engages in a first recess (44) in the cam (38) to hold the visor (10) in its lowered position, and a second tooth (34) which engages in a second recess (42) in the cam (38) to hold the visor (12) in its raised position. To move the visor (12) from its lowered to its raised position, the wearer manually rotates the operating lever (22) in the appropriate direction. Initial rotation of the operating lever about its pivotal connection (30) to the visor (10) withdraws the first tooth (36) of the operating lever (22) from the first recess (44) in the cam (38), to release the visor (10). Further rotation of the operating lever (22) rotates the visor (10) about the pivot post (18) until the second tooth (34) reaches the second recess (42) in the cam (38), whereupon the operating lever (22) rotates about its pivotal connection (30) to the visor (10) so as to move the second tooth (34) into the second recess (42), to latch the visor in the raised position. Similarly, to move the visor (10) to its lower position, the wearer rotates the operating lever (22) in the opposite direction, to disengage the second tooth (34) from the second recess (42), to then rotate the visor (10) to the lower position and to move the first tooth back into engagement with the first recess (44). The cam (38) has compliant projections (60 and 61), a respective one of which is engaged, in each of the lowered and raised positions of the visor (10), by the tooth (34) or (36) not engaged in the corresponding recess (42 or 44) in the cam (38), and which must be compressed during the initial movement of the operating lever (22), to inhibit inadvertent release of the latching engagement of the other tooth in the recess. The helmet may be provided with twin visors, each visor having its own driving and latching mechanism, the two mechanisms being located on opposite sides of the helmet.

Description: This invention relates to helmets and more particularly helmets having visors pivotably mounted thereon. Certain helmets, for example aircrew helmets are fitted with two visors. In an aircrew helmet it is often necessary to quickly move one or both of the visors from a retracted position to an operative position and to lock the visor in the required position. To facilitate this lever mechanisms have been proposed. For example, EP-A-0 270 368 representing the closest prior art discloses a helmet having a visor rotatably mounted on pivot means secured to the helmet and a visor displacement and latching mechanism for rotatably moving said visor between a lowered operative and a raised retracted position thereof, said mechanism comprising an operating lever which is rotatably mounted in relation to the visor pivot means; cooperating latching elements respectively and immovably fixed in relation to the helmet which engage and disengage upon rotation of the lever, in opposite senses, when said visor is disposed in the operative or retracted position; and cooperating visor driving elements respectively provided on the lever, which upon rotation of the lever about the visor pivot means, with said latching elements disengaged, cooperate to effect rotation of the visor from one to the other of the operative and retracted positions. This mechanism involving, as it does, a lot of moving parts is complex, and expensive to produce. One object of the present invention is to provide a helmet having an improved visor operating mechanism. The present invention consists in a helmet having a visor rotatably mounted on pivot means secured to the helmet and a visor displacement and latching mechanism for rotatably moving said visor between a lowered operative and a raised retracted position thereof, said mechanism comprising an operating lever which is rotatably mounted in relation to the visor pivot means and is also rotatable on a further pivot means secured to the visor and offset from said visor pivot means; pairs of cooperating latching elements, one element of each pair being provided on the lever and the other element of each pair being immovably fixed in relation to the helmet, which engage and disengage upon rotation of the lever, in opposite senses, about the further pivot means, when said visor is disposed in the operative or retracted position; and pairs of cooperating visor driving elements one element of each pair being respectively provided on the lever and the other element of each pair being immovably fixed in relation to the helmet, which upon rotation of the lever about the visor pivot means, with said latching elements disengaged, cooperate to effect rotation of the visor from one to the other of the operative and retracted positions. Preferably the cooperating latching elements comprise two angularly spaced pairs of cooperating latching elements said pairs respectively serving to latch the visor in the operative and retracted positions thereof. Also preferably the cooperating visor driving elements comprise two angularly spaced pairs of cooperating visor driving elements. Advantageously the elements of the pairs of the latching and visor driving elements which are immovably fixed in relation to the helmet are arranged with the latching elements adjacent respective of the visor driving elements so that as the lever is rotated to the point where it locates the visor in one of said operative or retracted positions by engagement of one pair of the cooperating visor driving elements, the latching element, adjacent the visor driving element which is secured to the helmet and is not engaged with its cooperating element, is engaged with its cooperating latching element. Also advantageously two visors are rotatably mounted on the helmet on coaxial visor pivot means at opposite sides of the helmet said visor displacement and latching mechanisms being provided at each side of the helmet for the respective visors and each visor being freely pivoted at the side of the helmet opposite the visor displacement and latching mechanism thereof on the visor pivot means. The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is a side view of a helmet with a visor in an operative position; Figure 2 is a side view of the helmet of Figure 1 with the visor in an intermediate position; Figure 3 is a side view of the helmet of Figures 1 and 2 showing the visor in a completely retracted position; Figure 4 is a side view of a helmet showing two visors, one in an operative position, one in a retracted position; Figure 5 is an exploded view of a visor mechanism according to the present invention; and Figure 6 is a diagram for showing the operation of the visor mechanism. In the drawings like parts are given the same reference numerals. Referring to the figures a helmet shown generally at (10) is provided with a first visor (12). A second visor (14) may further be provided. The visor (12) is pivotably mounted to the helmet by means of an arm (16) which is mounted on a pivot post (18), and the visor (14) is pivotally mounted on the helmet by means of an arm (15) also mounted on the pivot post. The pivot post extends from a plate (20) which is rigidly fixed to the side of the helmet in any known manner. It is preferred that the plate (20) should be secured at two points namely (20') and (20''). The double point mounting protects the shell of the helmet imposing less stress when the visor is moved by means of a lever (22). The lever (22) forms part of a visor displacement and latching mechanism shown generally at (24). The visor displacement and latching mechanism (24) includes the plate (20) and upstanding pivot post (18). The pivot post has a circular cross-section inner part (18') and a keyed part (18''). The keyed part includes two keying tracks (19). Arm (16) of the visor (12) is pivotally mounted on the pivot post. The visor is attached to the arm by means of any appropriate attachment at end (16') of the arm. The arm also includes an aperture (26), the function of which is referred to below. The lever (22) is mounted atop arm (16) on the pivot post (18), the post (18) passing through an aperture (28) in the lever so the lever is rotatable in relation to the post. The lever (22) is also pivotally mounted with respect to the arm (16). This further pivotal mounting is effected by a pivot means comprising a projection (30) which is received in the aperture (26) on the arm (16). The aperture (28) in the lever (22) is somewhat elongated to allow the lever to move relative to the pivot post (18) as the lever pivots on the arm (16). The lever further includes a hollowed out portion (32) into which project two teeth or projections (34) and (36). A profiled cam (38) is received within the hollowed out portion (32) of the lever (22). The cam is keyed on the key tracks (19) of the pivot post (18), so as to be immovably fixed to the plate (20). The cam includes two recesses (42) and (44) which are shaped to receive teeth (34) and (36) respectively. A second visor arm associated with the second visor is also pivotally mounted on the pivot arm above the lever. The above described elements are all held mounted on the pivot post (18) by any appropriate means, for example by a fixing plate (46). Referring to Figure 6, the lever (22) and the cam (38) are shown in more detail, with the lever (22) and lever arm (16) in the position they occupy when the visor is in the operative position. Tooth (36) and recess (44) form cooperating latching elements. Tooth (36) is located within recess (44) to hold the visor arm (16) against rotation in relation to the helmet shell. To move the visor from this position i.e. the operative position to the retracted position the helmet wearer moves lever (22). Initial movement of the lever in the clockwise direction causes the lever to pivot relative to the visor arm (16), about pivot means (26, 30). This causes the tooth (36) to move out of engagement with the recess (44), thereby disengaging the latching elements. Rotation of the lever (22) relative to visor arm (16) continues until the tooth (34) moves into engagement with profiled surface (52). Further movement of lever (22) causes the lever to rotate about pivot post (18), and to apply a turning moment to the visor arm (16), through engagement of the cooperating visor driving elements, namely the tooth (34) and profiled surface (52) of the cam, and engagement of lever (22) with arm (16) at projection (30). The visor arm (16) is therefore rotated with the lever (22), to move the visor upwards towards its retracted position. During this rotation, the tooth (34) slides along the cam surface (52), and is moved radially outwards by the increasing radius of the surface (52), until the tooth (34) reaches the recess (42). At this point, the other tooth (36), which has been moved inwards for engagement with the profiled surface (58) of the cam, engages an inwardly directed face (56) on the cam. This engagement prevents further rotation of the visor arm (16), so that continued movement of the lever (22) causes the lever to rotate about projection (30) to move the tooth (34) into engagement with the recess (42). The visor arm (16) is now held against rotation by the latching engagement of tooth (34) in recess (42), so holding the visor latched in the retracted position. As the tooth (34) moves into engagement with the recess (42), the other tooth (36) moves radially outwards. A compliant projection (61) is located on face (56) of the cam which is engaged by the tooth (36) just before the tooth (34) is aligned with the recess (42). The compliance of the projection (61) is provided by a slit (62) in the cam adjacent the projection. The compliant projection (61) is compressed by the tooth (36) as the tooth (34) is moved into the recess (42). As the tooth (36) moves radially outwards it becomes disengaged from the compliant projection. The tooth (36) must overcome the compliance of the projection before it can be moved radially inwards to disengage the tooth (34) from recess (42) to allow the visor to be moved from its retracted position. The compliant projection reduces the likelihood of inadvertent movement of the visor. When the helmet wearer wishes to move the visor from the retracted to the operative position the lever (22) is rotated in an anti-clockwise direction, to disengage tooth (34) from recess (42). Further rotation of the lever causes tooth (36) to engage and slide along profiled surface (58) until the tooth (34) engages inwardly directing face (50) of the cam, and tooth (36) is reseated in recess (44). The face (50) has a compliant projection (60) which provides a stop against tooth (34) in an anti-clockwise direction of movement of the lever (22) whilst recess (44) is engaged by tooth (36). Likewise compliant projection (61) on the face (56) of the cam is engaged by tooth (36) to prevent further clockwise rotation of lever (22) whilst tooth (34) engages cam recess (42). It is preferred that the teeth (34) and (36) also have a degree of compliance to allow the cooperation between faces (50) and (56) to be a relatively tight fit with the tooth extending slightly into a gap beyond each face (50) and (56). When two visors are used on the same helmet, each may have its own visor displacement and latching mechanism. For example, visor (12) will have visor displacement and latching mechanism (24) on the left-hand side of the helmet, whilst visor (14) will have a similar visor displacement and latching mechanism (24') on the right-hand side of the helmet. The only difference between these two mechanisms (24) and (24') is the relative positions of the elements making up the mechanism. Each visor is also pivotally mounted on the pivot post (18) at the side of the helmet opposite that at which the visor displacement and latching mechanism is provided. The mechanism can be axially loaded by means of a spring washer (not shown) to provide frictional location of the visor between the operative and retracted positions. It should be noted that the lever (22) need not be rotatably mounted directly on the visor pivot post (18), but only needs to be rotatable relatively to that post. It will be appreciated that additional visors may be provided on the helmet, each additional visor having a latching mechanism in accordance with the invention, or a more conventional latching mechanism.

Claims: A helmet (10) having a visor (12) rotatably mounted on pivot means (18) secured to the helmet (10) and a visor displacement and latching mechanism for rotatably moving said visor (12) between a lowered operative and a raised retracted position thereof, said mechanism comprising an operating lever (22) which is rotatably mounted in relation to the visor pivot means (18) and is also rotatable on a further pivot means (26, 30) secured to the visor (12) and offset from said visor pivot means (18); pairs of cooperating latching elements, (34,36,42,44) one element (34,36) of each pair being provided on the lever (22) and the other element of each pair being immovably fixed in relation to the helmet (10), which engage and disengage upon rotation of the lever (22), in opposite senses, about the further pivot means (26,30), when said visor (12) is disposed in the operative or retracted position; and pairs of cooperating visor driving elements (34,36,52,58) one element of each pair being respectively provided on the lever (22) and the other element (52,58) of each pair being immovably fixed in relation to the helmet (10), which upon rotation of the lever (22) about the visor pivot means (18), with said latching elements (34,36,42,44) disengaged, cooperate to effect rotation of the visor (12) from one to the other of the operative and retracted positions. A helmet (10) according to Claim 1, characterised in that the cooperative latching elements (34,36,42,44) comprise two angularly spaced pairs of cooperating latching elements (34,42,36,44) said pairs respectively serving to latch the visor (12) in the operative and retracted positions thereof. A helmet (10) according to Claim 2, characterised in that the cooperating visor driving elements (34,36,52,58) comprise two angularly spaced pairs of cooperating visor driving elements (34,52,36,58). A helmet (10) according to Claim 3, characterised in that the elements of the pairs of the latching (42,44) and visor driving elements (52,58) which are immovably fixed in relation to the helmet are arranged with the latching elements adjacent respective of the visor driving elements so that as the lever (22) is rotated to the point where it locates the visor in one of said operative or retracted positions by engagement of one pair of the cooperating visor driving elements, the latching element, adjacent the visor driving element which is secured to the helmet and is not engaged with its cooperating element, is engaged with its cooperating latching element. A helmet (10) according to Claim 4, characterised in that the elements of the pairs of cooperating latching (34,36) and visor driving elements (34,36) which are provided on the lever (22) each serve as both an element of each pair of latching elements and an element of each pair of visor driving elements. A helmet (10) according to Claim 4 or Claim 5, characterised in that the elements of the pairs of the latching (42,44) and visor driving elements (52,58) which are secured to the helmet (10) are provided on a profile of a cam (38) secured immovably to the helmet (10). A helmet (10) as claimed in Claim 6, characterised in that the elements of the visor driving elements (52,58) which are secured to the helmet comprise angularly spaced arcuate sections of said cam profile (38) and the latching elements on the profile comprise respective recesses (42,44) respectively adjoining said arcuate profile sections. A helmet (10) as claimed in Claim 7, characterised in that the elements of the pairs of latching elements provided on the lever comprise respective tooth projections (34,36) arcuately spaced apart, said projections serving also as an element respectively of the pairs of visor driving elements. A helmet (10) as claimed in any preceding claim, characterised in that the elements of the pairs of latching (42,44) and visor driving elements (52,58) provided on the lever (22) are integral with said lever (22). A helmet (10) as claimed in any preceding claim, characterised in that two visors (12,14) are rotatably mounted on the helmet (10) on coaxial visor pivot means (18) at opposite sides of the helmet, said visor displacement and latching mechanisms being provided at each side of the helmet for the respective visors and each visor being freely pivoted at the side of the helmet opposite the visor displacement and latching mechanism thereof on the visor pivot means. A helmet (10) according to Claim 8, characterised in that each tooth projection (34,36) has an inwardly directed face (48,54) which engages an inwardly directed face (50,56) on the cam (38) as the other tooth protection is moved into alignment with its respective recess. A helmet (10) according to Claim 11, characterised in that the inwardly directed face of the cam (50,56) has a compliant projection (60,61) which is compressed by the inwardly directed face of (48,54) of the tooth projection engaging the inwardly directed face of the cam as the other tooth projection is moved out of engagement with its respective recess, to inhibit inadvertent release of the latching engagement of the other tooth projection in the recess.

Inventors: DAMPNEY IAN TREVOR, DAMPNEY, IAN TREVOR
Applicants: HELMETS LTD, HELMETS LIMITED
Application year: 1992
Main classification: A42B3
IPC codes: A42B3