Helmet shield attaching mechanism and protective helmet comprising such a shield attaching mechanism

Abstract

A helmet shield attaching mechanism including a shield attaching base member and a shield. The shield attaching base member includes a stationary base member designed to be fastened to the shell, and a movable base member coupled to the stationary base member and to the shield. The shield attaching base member further includes an actuating base member pivotally connected to the stationary base member so that the actuating base member is adapted to rotate along a curved path and to abut against the movable base member, thereby moving the movable base member with respect to the stationary base member during a rotation of the shield. Also, a protective helmet including such a shield attaching mechanism.

Description

[0001] The present invention relates to a helmet shield attaching mechanism. In particular, even though not exclusively, the present invention relates to a helmet shield attaching mechanism configured to be used in combination with a motorcycle protective helmet.

[0002] The present invention also relates to a protective helmet comprising such a shield attaching mechanism.

[0003] As it is known in the art, the shell of a full-face helmet has generally a front opening called “eye port” which allows the user to see in front of him. Many helmets have this opening covered by a shield attached to the shell.

[0004] The shield is a transparent protective screen extending over the user's eyes and covering all or part of his / her face.

[0005] The shield must be maneuverable between at least two positions: the “fully closed” position, wherein the shield closes the eye port and protects the user's face, and the “fully open” position, wherein the shield is moved upwards so as not to longer close the eye port, leaving unprotected the user's face.

[0006] As required by the safety helmet standards currently in force (see for example Regulation UN ECE 22.06—clause 6.16.1), the shield needs to be removably attached to the shell of the helmet. At the same time, the shield needs to be maneuvered out of the field of vision with a simple movement of one hand.

[0007] Generally, the shield is attached to the helmet by means of a shield attaching mechanism.

[0008] Such a mechanism must be durable and precise in the movements. Moreover, it must allow an easy and quick removal and attachment of the shield.

[0009] Common mechanisms permit the shield to rotate around a fixed point so as to move along a circular trajectory. However, this configuration has some drawbacks.

[0010] The first one is that during the movement, when the shield reaches the “fully closed” position, it rubs against the gasket used to seal the eye port. This leads to an early wear of the gasket.

[0011] A further drawback is that, once the shield reaches the “fully open” position, it projects from the outer surface of the shell, being spaced apart from the latter. This causes an increase in the overall volume of the helmet.

[0012] Attaching mechanisms allowing a roto-translation movement of the shield are also known.

[0013] These mechanisms permit to overcome the drawbacks described above. They are generally formed by a base member, attached to the shell of the helmet, and the shield itself. The base member in turn comprises a stationary base member fixed to the shell of the helmet and a movable base member attached to the stationary base member so as to be reciprocally movable with respect to the stationary base member along a linear axis.

[0014] The shield is pivotally supported by the movable base member and in this way the center of rotation of the shield is moved in a controlled way by the mechanism itself during the movements of the shield.

[0015] In particular, at the beginning of the opening of the shield, namely when the latter starts to move from the “fully closed” position towards the “fully open” position, the shield can move forward, by spacing itself apart from the shell of a distance which is usually of about 3 mm.

[0016] The possibility to have this forward movement permits to obtain a specific intermediate position, the so-called “city position” of the shield. In the “city position” a reduced flow of air can enter inside the helmet. Such a flow of air is helpful in acting as anti-fog and in providing a cooling down effect.

[0017] When the shield is moved upwards from the “city position” towards the “open” position it substantially undergoes a rotation movement.

[0018] Finally, in proximity of the final position, namely when the “fully open” position is almost reached, the shield moves backward, towards the outer shell, so as to reduce the distance from the outer shell and consequently the overall volume of the helmet.

[0019] The movements from the “fully open” position towards the “fully closed” position take place in the same way, but in reverse order.

[0020] Advantageously, when the shield reaches the “fully closed” position from the “city position”, it undergoes a backward movement so that it does not rub against the sealing gasket of the eye port of the shell, thereby preventing an early wearing of the gasket.

[0021] A first example of roto-translation attaching mechanism is disclosed in EP 1856999B1.

[0022] In the shield attaching mechanism of EP1856999B1, a cam surface is provided on the shield and a cam follower portion is provided on the stationary base member so as to be able to abut against the cam surface.

[0023] When a force in a substantially rising direction is applied to the shield in the “fully closed” position, the cam follower portion follows the cam surface, and the shield can thus move forward to a front side together with the movable base member.

[0024] Once the shield reaches the “open” position, the cam follower is located in a recess of the cam surface and thanks to the provision of resilient means provided between the movable base member and the stationary base member, the shield can be retracted backward towards the outer shell.

[0025] A second example of roto-translation attaching mechanism is disclosed in EP2810577B1.

[0026] The mechanism of EP2810577B1 differs from the mechanism of EP1856999B1 in that the stationary base member comprises stopper means designed to interact with corresponding stopped means provided in the movable base member.

[0027] By varying the mutual position between the stopper means and the stopped means the position of the shield with respect to the outer shell at least in the fully closed position can be adjusted.

[0028] Both mechanisms, even if appreciated, are not free from drawbacks.

[0029] As a matter of fact, the above-mentioned mechanisms have a complex structure which makes the assembling of the mechanism and the subsequent attachment thereof to the helmet difficult.

[0030] Moreover, the adjustment operations to reach a satisfactory positioning of the shield with respect to the outer shell, in order to have a reliable “fully closed” position and to obtain reliable intermediate positions are time consuming and need to be carried out by skilled persons.

[0031] Furthermore, the interaction between a cam surface and a cam follower, even if reliable, can cause a jerky movement, which can hinder the user during the operation of the shield.

[0032] Lastly, the sliding between cam surface and cam follower can cause early wear of these components.

[0033] The main object of the present invention is therefore to provide a helmet shield attaching mechanism which solves at least partially the above-mentioned problems and drawbacks.

[0034] In particular, an aim of the present invention is to provide a helmet shield attaching mechanism which can be operated easily and quickly.

[0035] Another aim of the present invention is to provide a helmet shield attaching mechanism having a simplified and reliable structure.

[0036] Furthermore, an aim of the present invention is to provide a helmet shield attaching mechanism having a structure allowing a precise movement of the shield, reducing the risk of wear due to a mutual sliding friction between the components of the mechanism.

[0037] Lastly, an aim of the present invention is to provide a protective helmet having a shield which can be easily operated without affecting the outer dimensions of the helmet.

[0038] These and other objects and aims, that will better appear in the following description, are achieved by the helmet shield attaching mechanism according to claim 1 and by the protective helmet according to claim 18.

[0039] The advantages and the characteristic features of the invention will appear more clearly from the following description of preferred, but not exclusive, embodiments of the invention which refer to the accompanying figures in which:

[0040] FIG. 1 is a side view of the protective helmet of the present invention with the shield in the “fully closed” position;

[0041] FIG. 2 is a side view of the protective helmet of FIG. 1 with the shield in an “intermediate” position, the so-called “city position”;

[0042] FIG. 3 is a side view of the protective helmet of FIG. 1 with the shield in the “fully open” position;

[0043] FIG. 4 is a simplified side view of the protective helmet of FIG. 1, wherein the mutual arrangement between the guide portions of the shield and the helmet is schematically shown;

[0044] FIG. 5 is a view similar to FIG. 1, wherein the shield has been removed from the helmet;

[0045] FIG. 6 is a perspective view of the shield of the helmet shield attaching mechanism of the present invention;

[0046] FIG. 6A is an enlarged view of the particular of FIG. 6 indicated by the letter A;

[0047] FIG. 7 is an exploded view of the shield attaching base member of the helmet shield attaching mechanism of the present invention;

[0048] FIG. 8 is a side view of the shield attaching base member of FIG. 7;

[0049] FIG. 9 is a view similar to FIG. 8, wherein the movable base member of the shield attaching base member has been removed;

[0050] FIG. 10 is a view similar to FIG. 9, wherein the actuating base member has been removed;

[0051] FIG. 11 is a side view of an actuating base member of the shield attaching base member according to the present invention;

[0052] FIGS. 12 and 13 are respectively rear views of the components of FIGS. 10 and 11;

[0053] FIG. 14 is a side view of the assembly formed by the movable base member and the locking element of the shield attaching base member of the present invention;

[0054] FIGS. 15 and 16 are respectively separate side views of the movable base member and the locking element of the assembly shown in FIG. 14;

[0055] FIGS. 17, 18 and 19 are respectively rear views of FIGS. 14, 15 and 16;

[0056] FIG. 20 is a side view of the shield attaching mechanism of the present invention;

[0057] FIGS. 21-23 schematically show the mutual movements of the components of the shield attaching base member during the movements of the shield schematically shown in FIGS. 24-26;

[0058] FIG. 27 is a simplified view of FIG. 20;

[0059] FIG. 28 is similar to FIG. 27, wherein the axis, along which the movable base member of the shield attaching base member moves, has been positioned horizontally;

[0060] FIG. 29 schematically represents the roto-translation movement undergone by the shield of the helmet shield attaching mechanism of the present invention with respect to a simply rotational movement;

[0061] FIGS. 30-33 represent schematic views of the movements undergone by the movable base member and the actuating member of the helmet shield attaching mechanism of the present invention.

[0062] With reference to the attached figures, the present invention relates to a helmet shield attaching mechanism 10.

[0063] In the following, the term “upper” will indicate the area of the attaching mechanism and its individual components relatively further from the ground during the use, while the term “lower” will indicate the area of the attaching mechanism and its individual components relatively closer to the ground during the use.

[0064] The term “front” will indicate the area of the attaching mechanism and its individual components relatively closer to the face of the user, while the term “rear” will indicate the area of the attaching mechanism and its individual components relatively further from the face of the user.

[0065] The term “inner” will indicate the area of the attaching mechanism and its individual components relatively closer to the helmet to which the attaching mechanism is fastened, while the term “outer” will indicate the area of the attaching mechanism and its individual components relatively further from the helmet.

[0066] The attaching mechanism 10 comprises a shield attaching base member 12, designed to be fastened to a shell 2 of a protective helmet 1, and a shield 14, having at least one side portion 16 fastened to the shield attaching base member 12 (see FIGS. 1-4).

[0067] The shield 14 is a transparent protective screen. Once the shield 14 is attached by means of the mechanism 10 to the protective helmet 1, the shield 14 is designed to extend over the eyes of the helmet's user and to cover all or part of his / her face.

[0068] The shield attaching base member 12 in turn comprises a stationary base member 18, designed to be fastened to the shell 2 of the protective helmet 1, and a movable base member 20, coupled to the stationary base member 18 (see FIGS. 7-8) and to the shield 14 (see FIGS. 6 and 6A). The movable base member 20 is movable with respect to the stationary base member 18.

[0069] According to the invention, the shield attaching base member 12 further comprises an actuating base member 22 (see FIGS. 7 and 9).

[0070] The actuating base member 22 is pivotally connected to the stationary base member 18 (see FIG. 9), so that the actuating base member 22 is adapted to rotate along a curved path and to abut against the movable base member 20 thereby moving the movable base member 20 with respect to the stationary base member 18 during a rotation of the shield 14. Preferably, an operating end of the actuating base member 22 abuts against the movable base member 20 for moving the movable base member 20 with respect to the stationary base member 18 during a rotation of the shield 14.

[0071] As it will appear clear from the following description, the interaction between the actuating base member 22 and the movable base member 20 and the way in which the shield 14 is connected to the actuating base member 22 and to the movable base member 20 permit to obtain a helmet shield attaching mechanism 10 allowing a reliable roto-translation movement of the shield 14 with respect to the shell 2 of the helmet 1.

[0072] In particular, thanks to the provision of the actuating base member 22, the shield 14 can be easily operated by the user, so as to move from a “fully closed” position (see FIG. 1) to a “fully open” position (see FIG. 3) and vice versa, being also able to get into a specific “intermediate position” (see FIG. 2), the so-called “city position”, wherein the shield 14 is spaced apart from the shell 2 of the helmet 1.

[0073] As shown in FIGS. 1-4, the attaching mechanism 10 of the present invention is designed to be applied to the shell 2 of the protective helmet 1.

[0074] In particular, the protective helmet 1 can be provided with two helmet shield attaching mechanisms 10, a first helmet shield attaching mechanism 10 being applied on a left side portion of the shell 2 and a second helmet shield attaching mechanism 10 being applied on a right side portion of the shell 2.

[0075] Preferably the protective helmet 1 is a full-face helmet adapted to be worn by motorcyclists. Nevertheless, the protective helmet 1 can also be advantageously used by cyclists, skiers or in other sport fields where an effective protection of the user's head is needed.

[0076] As it is known in the art, the protective helmet 1 in addition to the shell 2, made preferably of a composite or thermoplastic material, also comprises a comfort liner, designed to be in contact with the user's head when the protective helmet 1 is worn by the user, and an impact absorbing liner, interposed between the shell 2 and the comfort liner.

[0077] The comfort liner and the impact absorbing liner are positioned inside the shell 2 and are not visible in the attached figures.

[0078] The shell 2 comprises a front opening 3, the so-called “eye port”, which allows the user to see in front of him (see FIG. 5).

[0079] In the fully closed position the shield 14 covers the front opening 3 so as to protect the user's face and to adhere to the outer shell 2 (see FIG. 1), while, in the fully open position, the shield 14 does not cover the front opening 3, leaving unprotected the user's face (see FIG. 3).

[0080] As it will be explained in detail in the following, also in the fully open position the shield 14 is close to the shell 2 thanks to the roto-translation movement imparted to it by the attaching mechanism 10. As a matter of fact, in proximity of the fully open position, the shield 14 undergoes a backward movement. Such a backward movement is indicated by the letter B in FIG. 3.

[0081] As anticipated, during the passage from the fully closed position to the fully open position the shield 14 can also get into an intermediate position (the city position) wherein the shield is spaced apart, of about 3 mm, from the front opening 3, so as not to longer adhere to the outer shell and to allow the entrance of a reduced flow of air inside the protective helmet 1 (see FIG. 2). Such an intermediate position is reached thanks to the possibility of the shield 14 to undergo a forward movement, schematically indicated by the letter F in FIG. 2.

[0082] As it is well known in the art, the shield 14 is made of a rigid transparent material which is preferably chosen in the group comprising acrylic material or polycarbonate.

[0083] The shield 14 has an arcuate shape so as to match with the underlying surface of the shell 2 of the protective helmet 1.

[0084] As clearly shown in FIGS. 6 and 6A, the shield 14 preferably comprises a first guide portion 24, suitable for being connected to the movable base member 20, and a second guide portion 26, suitable for being connected to the actuating base member 22.

[0085] The mutual positioning of the shield 14 with respect to the movable base member 20 and the actuating base member 22 is shown in FIGS. 20 and 27.

[0086] As schematically shown in FIGS. 24-26, during the passage from the fully closed position (FIG. 24) to the fully open position (FIG. 26) the shield 14 is adapted to rotate around the first guide portion 24.

[0087] Preferably, the first guide portion 24 and the second guide portion 26 are integral with the shield 14.

[0088] First and second guide portions 24, 26 are positioned at both side portions 16 of the shield 14 and are designed to be coupled to corresponding shield attaching base members 12, positioned at the left side portion and at the right side portion of the shell 2.

[0089] Preferably, the first guide portion 24 and the second guide portion 26 of the shield 14 are projecting portions provided at an inner surface 15 of the shield 14. Consequently, during the normal use of the helmet 1, such guide portions 24, 26 are not in sight.

[0090] As shown in detail in FIG. 6A, the first guide portion 24 advantageously consists of a cylindrical projecting portion 25. The cylindrical projecting portion 25 preferably extends along a longitudinal axis X1, having its origin in the center C1 (see FIGS. 1-4). Advantageously, said longitudinal axis X1 is perpendicular to the region of the inner surface 15 of the shield 14 on which the first guide portion 24 is arranged.

[0091] Preferably, the cylindrical projecting portion 25 is hollow.

[0092] At the distal end of the first guide portion 24, namely the end situated away from the shield 14, at least one protrusion 28 is provided. Said protrusion 28 extends outwardly from the first guide portion 24 substantially perpendicularly to the longitudinal axis X1.

[0093] In a preferred embodiment, the first guide portion 24 is provided with at least two protrusions 28 positioned on opposite sides of the cylindrical projecting portion 25.

[0094] As it will be explained in the following, the function of the protrusions 28 is to allow a safe and easy attachment and removal of the shield 14 from the attaching mechanism 10 and thus to permit a safe and easy attachment and removal of the shield 14 from the helmet 1.

[0095] The second guide portion 26 is spaced apart from the first guide portion 24, being positioned towards the central portion of the shield 14.

[0096] The second guide portion 26 preferably consists of a projecting pin 30 extending along a longitudinal axis X2, having its origin in the center C2 (see FIGS. 1-4). Preferably, the projecting pin 30 extends perpendicularly to the region of the inner surface 15 of the shield 14 on which the pin is arranged.

[0097] Preferably, the center C2 is spaced apart from the center C1 of a distance SR (see FIGS. 4 and 24-26). Such a distance SR can vary between 20 and 60 mm, depending on the geometry of the shield 14.

[0098] As shown in FIG. 6A, in a preferred embodiment, the projecting pin 30 is provided with a support member 32 at the end proximal to the inner surface 15 of the shield 14.

[0099] The support member 32 has larger dimensions than that of the projecting pin 30. The support member 32 extends along a transversal axis Y, which is substantially parallel to the inner surface 15 of the shield 14 and perpendicular to the longitudinal axis X2 of the projecting pin 30 (see FIG. 4).

[0100] Advantageously, the side surface of the support member 32 is provided with at least one indentation 33 (see FIGS. 4 and 6A).

[0101] As it will be explained in the following, the function of the projecting pin 30 is to permit the coupling between the shield 14 and the actuating base member 22, while the function of the support member 32, which is designed for engaging the movable base member 20, is to improve the guidance of the shield 14 during the rotations around the first guide portion 24 of the movable base member 20.

[0102] With reference to FIGS. 7 and 10, the stationary base member 18 of the shield attaching base member 12 has preferably a plate-like base structure 19 which is delimited by a projecting perimetral boundary 34. The boundary 34 protrudes from the outer surface of the base structure 19.

[0103] The stationary base member 18 is preferably designed to be removably fastened to the shell 2 of the helmet 1 by means of removable fastening means 36A, 36B, 36C. Advantageously the fastening means 36A, 36B, 36C are adapted to be inserted inside corresponding through holes 38A, 38B, 38C provided in the plate-like base structure 19 so as to be fixed inside corresponding fastening seats (not shown in the attached figures) positioned at the shell 2.

[0104] With reference to FIG. 9, the stationary base member 18 can comprise a first guide portion 40.

[0105] The first guide portion 40 is preferably a recess formed in the stationary base member 18. As shown in FIG. 9, the first guide portion 40 can have an elongated shape whose major axis extends along an axis T representing the travel direction of the movable base member 20. As a matter of fact, as it will be explained in detail in the following, during the movements of the shield 14, the movable base member 20 moves back and forth along the axis T.

[0106] Preferably, the first guide portion 40 is delimited by two substantially linear surfaces 41A, which extend parallel to the axis T. These linear surfaces 41A can be at least partially closed by a front curved surface 41B and rear curved surface 41C. Advantageously, front and rear curved surfaces 41B, 41C have the same radius.

[0107] In a preferred embodiment, the perimeter profile of the first guide portion 40 is provided with one or more openings, not visible in the following figures, having the function to ease the coupling of the movable base member 20 to the stationary base member 18.

[0108] Moreover, the first guide portion 40 can be delimited by a perimeter edge. Such an edge in some parts can be provided with a retention small tooth having the function to guarantee a firm connection between the movable base member 20 and the stationary base member 18.

[0109] Preferably, in the first guide portion 40 a center C4, which lies on the axis T and is equally distant from the front curved surface 41B, can be identified.

[0110] Similarly, in the first guide portion 40 a center C5, which lies on the axis T and is equally distant from the rear curved surface 41C, can be identified.

[0111] The stationary base member 18 can also comprise a second guide portion 42. The second guide portion 42 can be a curved slot centered on a center C3 and having radius R (see FIGS. 9 and 10).

[0112] As shown in FIGS. 27 and 28, once the shield 14 is attached to the shield attaching base member 12, the center C3 is spaced from the center C1 of a distance x, measured along a line parallel to the axis T. Moreover, the center C3 is spaced from the axis T of a distance y, measured along a line perpendicular to the axis T.

[0113] The stationary base member 18 can further comprise first fastening means 44 which are preferably positioned at the upper portion and at the lower portion of the base member 18 (see FIGS. 5 and 9).

[0114] Advantageously, the first fastening means 44 comprise at least one elongated guide track 45 directed along a direction T1, T2 parallel to the axis T representing the travel direction. Preferably, the first fastening means 44 comprise a couple of elongated guide tracks 45 spaced to each other and directed along the axis T (see FIG. 10).

[0115] Furthermore, the stationary base member 18 can comprise second fastening means 46 positioned at the front portion of the base member 18 (see FIGS. 5 and 9).

[0116] Preferably the second fastening means 46 comprise a single elongated guide track 47 directed along a direction parallel to the axis T1 and T (see FIGS. 9 and 10).

[0117] Advantageously, similarly to the first guide portion 40, the second fastening means 46 can be provided with a retention small tooth having the function to guarantee a firm connection between the movable base member 20 and the stationary base member 18. As it will be explained in the following, first and second fastening means 44, 46 permit the movable coupling between the stationary base member 18 and the movable base member 20.

[0118] Furthermore, the stationary base member 18 is provided with coupling means 48 for pivotally connection of the actuating member 22 to the stationary base member 18 (see FIGS. 7 and 10).

[0119] The coupling means 48 can consist of a projecting pin 49 centered on the center C3 (see FIGS. 7 and 10).

[0120] The movable base member 20, similarly to the stationary base member 18, has preferably a plate-like base structure 50 (see FIGS. 7 and 15).

[0121] As shown in FIG. 8, the movable base member 20 has a perimeter profile 51 designed to remain inside the projecting boundary 34 of the stationary base member 18 when the movable member 20 and the base member 18 are coupled to each other.

[0122] The movable base member 20 preferably comprises first guide seats 52 which are preferably positioned at the upper portion and at the lower portion of the movable base member 20 (see FIGS. 7, 14-15, 17-18).

[0123] The first guide seats 52 are designed to slidably engage the first fastening means 44 of the stationary base member 18.

[0124] Advantageously, the first guide seat 52 can consist of through openings. Each opening can have an upper edge 54A and a lower edge 54B (see FIGS. 14-15).

[0125] The upper edge 54A and lower edge 54B of each opening 52 are designed to slidably engage the elongated guide tracks 45 of the first fastening means 44 so as to permit a translation movement of the movable base member 20 with respect to the stationary base member 18 along the axis T representing the travel direction.

[0126] As shown in FIG. 7, a rear wall of the opening 52 provided at the lower portion of the movable base member 20 can be provided with a projection 55 designed to engage a repulsive coil 59, such a repulsive coil 59 being interposed between the movable base member 20 and a front edge of the stationary base member 18.

[0127] The movable base member 20 can further comprise second guide seats 56 provided at the front upper portion of the perimeter profile 51 (see FIGS. 14-15 and 17-18).

[0128] Preferably, such second guide seats 56 consist of at least one indentation 57 of the perimeter profile 51.

[0129] The second guide seats 56 are designed to engage the second fastening means 46 of the stationary base member 18. In particular, the indentation 57 is adapted to slidably engage the elongated guide track 47.

[0130] The second guide seats 56 work in combination with the first guide seats 52 in guiding the translation movements of the movable base member 20 with respect to the stationary base member 18 along the axis T.

[0131] Preferably, the movable base member 20 also comprises a coupling portion 58 for coupling the movable base member 20 to the first guide portion 24 of the shield 14.

[0132] Advantageously, the coupling portion 58 consists of a recess provided in the movable base member 20. The profile of the coupling portion 58 is designed to match the outer profile of the first guide portion 24.

[0133] In particular the coupling portion 58 has a circular profile suitable for matching the outer profile of the cylindrical projecting body 25 of the shield 14, so as to permit a rotation of the latter when it is inserted inside the coupling portion 58. In detail, the first guide portion 24 of the shield 14 is designed to rotate around a center C8 defined in the coupling portion 58 of the movable base member 20 (see FIGS. 14-15).

[0134] The coupling portion 58 has a top edge 60 which is provided with retaining means 62 (see FIG. 7). The retaining means 62, which preferably consist in an undercut provided at the top edge 60, are adapted to engage with the protrusions 28 of the first guide portion 24, so as to assure that no unintentional release of the shield 14 from the movable base member 20 can happen.

[0135] As shown in FIGS. 7 and 15, the top edge 60 of the coupling portion 58 can also have a slit 64 which, as it will be explained in the following, is designed to be selectively closed by a first stop member 66 provided in a separate locking element 68. The inner surface of the coupling portion 58 can project from the inner surface of the movable base member 20 to abut against the stationary base member 18 so as to be slidably housed inside the first guide portion 40.

[0136] Preferably, the inner surface of the coupling portion 58 has a circular profile having a radius corresponding to the radius of the front and rear curved surfaces 41B, 41C of the first guide portion 40.

[0137] Consequently, due to the mutual arrangement between the coupling portion 58 of the movable base member 20 and the first guide portion 40 of the stationary base member 18, the front and rear curved surfaces 41B, 41C can act as stop limits of the sliding movements along the axis T of the movable base member 20 with respect to the stationary base member 18. Moreover, the extension of the linear surfaces 41A of the first guide portion 40 can define the maximum distance which can be covered by the movable base member 20 with respect to the stationary base member 18 along the axis T.

[0138] Furthermore, as it is shown for example in FIGS. 14-15, the movable base member 20 can be provided with a guiding track 70. The guiding track 70 comprises a groove 71 having a curved profile. The curved groove 71 extends preferably along a circumference segment centered on the center C8 of the coupling portion 58 and having a radius SR, corresponding to the distance between the center C1 of the first guide portion 24 and the center C2 of the second guide portion 26 of the shield 14. Consequently, the center C8 of the curved groove 71 coincides with the center C1 of the first guide portion 24 when the shield 14 is coupled to the movable base member 20 (see FIG. 20).

[0139] Preferably, the guiding track 70 has a width which corresponds to the width of the support member 32. Moreover, the internal surface of the groove 71 of the guiding track is provided with indentations 72 (see FIGS. 14-15) corresponding to the indentation 33 of the support member 32 so as to permit a better guidance of the support member 32 inside the curved groove 71 of the guiding track 70.

[0140] In particular, the engagement between the internal surface of the groove 71 with the indentation 33 of the support member 32 advantageously permits to maintain the shield 14 parallel to the movable base member 20, and consequently to the stationary base member 18, when the shield 14 moves up and down.

[0141] Furthermore, the interaction between the indentations 72 of the curved groove 71 and the support member 32 permits to easily block the shield 14 in various intermediate positions between the fully closed position and the fully open position.

[0142] Preferably, the guiding track 70 has a height which corresponds to the height of the second guide portion 26 of the shield 14. In this way the inner surface 15 of the shield 14 is in close proximity with the outer surface of the guiding track 70 when the shield 14 is coupled to the movable base member 20.

[0143] Advantageously, the contour of the guiding track 70 is open. Preferably, the contour of the guiding track 70 is open at its upper end. Advantageously, the contour of the guiding track 70 is provided at the upper end with a slit 73 which, as it will be explained in the following, is designed to be selectively closed by a second stop member 97 provided in the locking element 68 (see FIGS. 14-16).

[0144] Furthermore, with reference to FIGS. 7, 8, and 14, the movable base member 20 can also be provided with a first releasing guide 74, provided at the upper portion of the movable base member 20, and a second releasing guide 76, provided at the lower portion of the movable base member 20.

[0145] Preferably, the first releasing guide 74 is positioned close to the upper end of the guiding track 70. The second releasing guide 76 can be positioned close to the lower end of the guiding track 70.

[0146] First and second releasing guides 74, 76 consist of projecting elements having a jutting distal end.

[0147] As it will be explained in detail in the following, such releasing guides 74, 76 are designed to keep in position a further element, a locking element 68, of the helmet shield attaching mechanism 12.

[0148] With reference to FIGS. 7 and 9, the shield attaching mechanism 12 also comprises an actuating base member 22. Preferably the actuating base member 22 is a separate element which is interposed between the stationary base member 18 and the movable base member 20.

[0149] Advantageously, as it is shown in detail in FIGS. 11 and 13, the actuating base member 22 can be a lever or rod having a first end 77, designed to be pivotally connected to the stationary base member 18, and a second end 81, designed to be connected to the second guide portion 26 of the shield 14.

[0150] Preferably, the actuating base member 22 is pivotally connected to the stationary base member 18 at the coupling means 48 so as to be able to rotate around the center C3 (see FIG. 9).

[0151] In detail, the actuating member 22 can have at the first end 77 a first through hole 78 designed to be engaged by the projecting pin 49.

[0152] The actuating member 22 can be pivotally connected to the projecting pin 49 by means of a sleeve nut 79 having an internal thread on which a corresponding bolt 80 can be screwed after having engaged the pin 49 and the hole 78 (see FIG. 7).

[0153] The sleeve bolt 80 secures the actuating member 22 to the stationary base member 18 allowing the actuating member 22 to pivot around the center C3.

[0154] Preferably the actuating base member 22 has the second end 81, opposite to the first end 77, provided with coupling means 82 by means of which the actuating member 22 can be removably coupled to the second guide portion 26 of the shield 14.

[0155] Preferably, the coupling means 82 are engaged by the second guide portion 26 of the shield 14 through the groove 71 provided in the guiding track 70. In detail, the coupling means 82 comprises a through hole 84 designed to be engaged by the projecting pin 30 of the second guide portion 26. As a matter of fact, even if the actuating base member 22 is interposed between the stationary base member 18 and the movable base member 20, the through hole 84 is accessible through the groove 71 of the guiding track 70.

[0156] Preferably, the second end 81 is also provided with a shoe 86 designed to slidably engage the inner portion of the guiding track 70 provided in the movable base member 20, when the movable base member 20 is coupled to the stationary base member 18.

[0157] In particular, during the rotation of the actuating base member 22, the shoe 86 is able to slide along the external profile of the inner portion of the guiding track 70.

[0158] Preferably, the shoe 86 encircles partially the coupling means 82. In a preferred embodiment, the shoe 86 consists of walls projecting from the outer surface of the actuating member 22.

[0159] The function of the shoe 86 is to maintain the actuating base member 22 coupled to the movable base member 20, once the shield 14 is removed from the helmet shield attaching mechanism 10.

[0160] As shown in FIG. 9, the second end 81 of the actuating member 22 is designed to move along a curved profile having radius R. In this way, the second end 81 is designed to cover a curved surface which corresponds to the second guide portion 42 of the stationary base member 18.

[0161] Advantageously, in a further embodiment, the shoe 86 can also project from the inner surface of the actuating member 22, so as to be able to slidably engage with the secondary guide portion 42 of the stationary base member 18, when the actuating base member 22 is coupled to the stationary base member 18.

[0162] As anticipated, the helmet shield attaching mechanism 12 of the invention can also comprise a locking element 68. In detail, the locking element 68 is designed to interact with the movable base member 20.

[0163] The locking element 68 can be a manipulation lever designed to be pivotally connected to the movable base member 20.

[0164] Preferably, the locking element 68 can be pivotally fixed to the movable base member 20 by means of removable fastening means, for example a screw, designed to engage a corresponding seat provided in the movable base member 20.

[0165] Alternatively, the locking element 68 can be provided at its intermediate portion with a projecting portion 88 extending from the inner surface of the locking element 68 and designed to be inserted inside a corresponding seat 90 arranged in the movable base member 20. Preferably, the projecting portion 88 is a retention tooth.

[0166] The locking element 68 has a first engaging pawl 92, positioned at the upper portion of the locking element 68, and a second engaging pawl 94, positioned at the lower portion of the locking element 68 (see FIG. 7).

[0167] Additionally, the locking element 68 can have a third engaging pawl 93, provided at the rear portion of the locking element 68 (see FIGS. 16 and 19).

[0168] First engaging pawl 92 and second engaging pawl 94 are designed to slidably engage respectively the first releasing guide 74 and the second releasing guide 76 of the movable base member 20 so that, during the normal use, the locking element 68 can remain affixed to the movable base member 20.

[0169] Similarly, the third engaging pawl 93 is designed to slidably engage a corresponding releasing guide 75 provided on the movable base member 20 (see FIG. 15).

[0170] Moreover, as anticipated, the locking element 68 comprises a first stop member 66, provided at the rear surface of the locking element, and a second stop member 97, provided at the front surface of the locking element (see FIGS. 14 and 16).

[0171] The first stop member 66 is designed to selectively close the slit 64 provided at the top edge 60 of the coupling portion 58, while the second stop member 97 is designed to selectively close the slit 73 provided at the upper end of the guiding track 70.

[0172] The locking element 68 can pivot around an axis which passes for the projecting portion 88 or for the seat on which the fastening means connecting the element 68 to the movable member 20 are fixed.

[0173] Such projecting portion 88 or seat acts as a fulcrum, being centered on a center C6 (see FIG. 8). The locking element 68 is movable against the force exerted by a repulsive coil 96, partially visible in FIG. 8, interposed between abutting surfaces provided in the locking element 68 and in the movable base member 20.

[0174] In particular, by rotating around its center of rotation C6, the locking element 68 can move from a first position, wherein the first stop member 66 closes the slit 64 and the second stop member 97 closes the slit 73, and a second position, wherein the first stop member 66 and the second stop member 97 are respectively spaced apart from the slit 64 and the slit 73, and vice versa.

[0175] The locking element 68 is also provided with a grip portion 98 designed to be grasped by the fingers of the user (see FIGS. 7 and 16).

[0176] Preferably, the stationary base member 18, the movable base member 20 and the actuating base member 22 are made of polymeric material.

[0177] Advantageously, the locking element 68 can be made of metallic material.

[0178] It is now disclosed how the various elements of the helmet shield attaching mechanism 10 can be assembled.

[0179] Firstly, the actuating base member 22 is connected to the stationary base member 18 by inserting the through hole 78 inside the projecting pin 49 and by blocking it by means of the sleeve nut 79 and the bolt 80.

[0180] Afterwards, the assembly formed by the stationary base member 18 and the actuating base member 22, which is shown in FIG. 9, is fastened to the shell 2 by inserting the fastening means 36A, 36B, 36C inside the corresponding through holes 38A, 38B, 38C.

[0181] In a subsequent step, the locking element 68 is coupled to the movable base member 20 by means of a screw or by inserting the retention teeth 88 inside the seat 90 and by compressing the repulsive coil 96 positioned between the locking element 68 and the movable base member 20.

[0182] After the coupling, the locking element 68 is rotated around the center C6 so that the first engaging pawl 92 and the second engaging pawl 94 are slidably inserted inside the corresponding first releasing means 74 and the second releasing means 76 of the movable base member 20.

[0183] Following such a rotation of the locking element 68 which is favored by the force of the repulsive coil 96, the first stop member 66, provided at the rear surface of the locking element 68, moves in proximity to the coupling portion 58 so as to close the slit 64 provided at the top edge 60 of the coupling portion 58.

[0184] Similarly, following the rotation of the locking element 68, the second stop member 97, provided at the front surface of the locking element 68, moves in proximity to the guiding track 70 so as to close the slit 73.

[0185] In this way, the top edge 60 of the coupling portion 58 and the contour of the guiding track 70 are completed. Such an assembly is shown in FIGS. 14 and 17. Subsequently, the movable base member 20 with the locking element 68 is coupled to the assembly formed by the stationary base member 18 and the actuating base member 22 by means of the engagement of the first guide seats 52 and the second guide seats 56 with the corresponding first fastening means 44 and the second fastening means 46. During such a coupling operation a repulsive coil 59 is interposed between the base stationary member 18 and the movable base member 20, so that when the latter moves forward with respect to the stationary base member 18 along the axis T, the repulsive force exerted by the coil 59 is suitable to push the movable base member 20 back.

[0186] The mutual positioning between first and second guide seats 52, 56 with respect to first and second fastening means 44 and 46 guarantees that, once the movable base member 20 is coupled to the stationary base member 18, the inner surface, namely the bottom section, of the coupling portion 58 is slidably housed, in an abutment relationship, inside the first guide portion 40 of the stationary base member 18. It is also guaranteed that the inner portion of the guiding track 70 engages the shoe 86 provided at the second end 81 of the actuating base member 22.

[0187] In a subsequent step, the locking element 68 is rotated against the force exerted by the repulsive coil 96, around its center of rotation C6, so as to respectively space apart the first stop member 66 from the slit 64 provided at the top edge 60 of the coupling portion 58 and the second stop member 97 from the slit 73 of the guiding track 70.

[0188] In this way the coupling of the shield 14 with the movable base member 20 and the actuating base member 22 is permitted. In particular, such a coupling is carried out by inserting the first guide portion 24 inside the coupling portion 58 of the movable base member 20 and by inserting, through the slit 73, the second guide portion 26 inside the coupling means 82 provided at the second end 81 of the actuating base member 22.

[0189] Preferably, such a coupling step is carried out by maintaining the shield 14 in a fully open position with respect to the shell 2.

[0190] Then the locking element 68 is released and due to the force exerted by the repulsive coil 96, the first stop member 66 moves in proximity to the coupling portion 58 so as to close the slit 64 and the second stop member 97 moves in proximity to the guiding track 70 so as to close the slit 73.

[0191] In this way, the top edge 60 of the coupling portion 58 and the contour of the guiding track 70 are completed and it is no longer possible the releasing of the shield 14 from the movable base member 20 and the actuating base member 22. In particular, the protrusions 28 of the first guide portion 24 are firmly locked inside the coupling portion 58 and the second guide portion 26 is firmly locked inside the guiding track 70. In detail, with reference to the second guide portion 26, the support member 32 is firmly blocked inside the guiding track 70.

[0192] In this way, all the components of the actuating mechanism 12 are held together.

[0193] Now, the operation of the helmet shield attaching mechanism 10 will be described by referring to FIGS. 20-33.

[0194] In particular, the movements undergone by the shield 14 during the passage from a “fully closed” position, schematically shown in FIG. 24, to a “fully open” position, schematically shown in FIG. 26, will be disclosed. The movements from the “fully open” position towards the fully closed position take place in the same way, but in a reverse order.

[0195] As previously mentioned, the axis T represents the travel direction along which the movable base member 20 moves back and forth with respect to the stationary base member 18.

[0196] The center C7 schematically represents the center of the shoe 86 of the actuating member 22. Once the shield 14 is coupled to the actuating base member 22 the center C7 of the actuating base member 22 coincides with the center C2 of the second coupling portion 26.

[0197] In FIGS. 27 and 28, as angle α it is indicated the angle formed by the longitudinal axis of the actuating base member 22 and the axis T.

[0198] As radius R it is indicated the distance between the center C3, namely the center of rotation of the actuating base member 22, and the center C7.

[0199] Once the shield 14 is coupled to the movable base member 20, as angle β it is indicated the angle formed by the axis T and the radius SR, namely the radius joining the center C8, defined in the movable base member 20 and coinciding with the center C1 of the first guide portion 24 of the shield 14, and the center C7 of the actuating base member22.

[0200] It is assumed that in the “fully close” position the center C8, and thus the center C1, coincides with the center C5 of the first guide portion 40. In this configuration, the coupling portion 58 is abutting against the rear curved surface 41C. However, such a condition is not indispensable for the correct functioning of the helmet shield attaching mechanism 10.

[0201] FIG. 28 is similar to FIG. 27 but for clarity reason the axis T has been put on a horizontal line.

[0202] When the shield 14 is moved upwards from the “fully close” position of FIG. 24, the first guide portion 24 of the shield 14, which is positioned inside the coupling portion 58, starts to rotate around the center C1, and thus around the center C8 (see FIG. 25).

[0203] Such a rotation of the first guide portion 24 also causes a corresponding rotation of the second guide portion 26 which is engaged at the center C7 inside the coupling means 82 of the actuating base member 22. Such an engagement is carried out through the guiding track 70 of the movable base member 20.

[0204] The rotation of the second guiding portion 26 causes as a consequence a rotation of the actuating base member 22 around the center C3.

[0205] Due to the offset position between the centers C8 and C3 and due to the difference between the radius R, connecting the center C3 with the center C7, and the radius SR, connecting the center C8 with the center C7 and defining the curve along which the guide track 70 extends (see FIGS. 27 and 28), the second guide portion 26, causes the rotation of the shoe 86 which exerts during its movements a forward force against the guide track 70 of the movable base member 20.

[0206] Since the movable base member 20 is movable with respect to the stationary base member 18, such a forward force causes a forward sliding of the movable base member 20 with respect to the stationary base member 18 along the axis T.

[0207] The coupling portion 58 starts to space apart from the rear curved surface 41C and thus the center C5 does not longer coincide with the center C1 and C8.

[0208] Following such a forward sliding movement the initial distance between the center C8 (and C1) and the center C3 decreases, as it is schematically shown in FIGS. 31 and 32, wherein it is visible how the second guide portion 26 of the shield moves along a curved path which progressively distances itself from the center C5.

[0209] Consequently, thanks to this forward movement, the shield undergoes a forward translation so as to assume an intermediate position, shown in FIG. 2, wherein it is spaced apart from the shell.

[0210] If the shield continues to rotate around the first guide portion 24, the second guide portion 26 in turn continues to roto-translate around the center C3. The second guide portion 26 is still engaged inside the guiding track 70 and the shoe 86 continues in exerting a forward force against the movable base member 20 which moves forward along the axis T.

[0211] As a matter of fact, as schematically shown in FIGS. 31-32, the second guide portion 26 of the shield 14 still moves along the curved path defined by the guiding track 70 resulting in an increase of the distance between the center C5 and the center C7.

[0212] The combination of the rotation of the second guide portion 26 of the shield 14 around the center C3 and the rotation of the first guide portion 24 around the center C8 results in a roto-translational movement of the shield 14 with respect to the shell of the helmet.

[0213] The difference between such a roto-translation movement and a simple rotational movement is schematically shown in FIG. 29, wherein the roto-translation trajectory followed by the shield 14 of the present invention is indicated by the letter RT, while a trajectory which would be followed by a shield able to simply rotate is indicated by the letter R.

[0214] Due to the mutual positioning between the stationary base member 18, the actuating base member 22 and the movable base member 20, the forward movement of the movable base member 20 continues until the distance between the center C8 and the center C3 reaches a minimum value.

[0215] It is assumed that in such a configuration (schematically shown in FIG. 32) the inner surface of the coupling portion 58 abuts against the front curved surface 41B of the first guide portion 40 of the stationary base member 18 and that the center C8 coincides with the center C4. However, such a mutual condition between coupling portion 58 and front curved surface 41B is not indispensable for the correct functioning of the helmet shield attaching mechanism 10.

[0216] The difference between the maximum and the minimum distance between the center C8 and the center C3 can vary in a range of about 3 mm, depending on the geometry of the actuating member and the movable member. Obviously, such a value can be varied if required.

[0217] The distance traveled by the movable base member thus corresponds to the distance between the center C4 and the center C5 of the first guide portion 40.

[0218] Furthermore, since the distance between the center C8 and the center C3 depends on the angles αand β, which are linked to each other by a trigonometric relationship, the variation of the distance between the center C8 and the center C3 is not linear but higher at the beginning and at the end of the rotation of the shield.

[0219] If the shield 14 still rotates upwards around the first guide portion 24, the distance between the center C8 and the center C3 tends to increase, so that the movable base member 20 is pushed backward by the actuating base member 22, in particular by the shoe 86.

[0220] Such a backward movement, which is schematically indicated by the letter B in FIG. 26, allows the shield 14 to be positioned close to the shell 2 of the helmet 1 when the shield reaches the “fully open” position.

[0221] In this position, by acting on the locking element 68 it is also possible to release the shield from the movable base member 20.

[0222] As a matter of fact, the user, by acting on the grip portion 98, can rotate the locking element 68 around its center C6 so that the first stop member 66 is spaced apart from the slit 64 of the coupling portion 58 leaving open the top edge 60 of the coupling portion 58 and the second stop member 97 is spaced apart from the guiding track 70 leaving open the slit 73.

[0223] Through such apertures, it is possible for the user to detach the shield 14 from the movable base member 20 since the protrusions 28 are no longer retained by the retaining means 62 and the second guide portion 26, in particular the projecting pin 30 and the support member 32, are no longer blocked inside the guiding track 70.

[0224] It is clear now how the present invention allows to achieve the predefined objects.

[0225] As a matter of fact, thanks to the provision of the pivoting actuating member, separated from the stationary base member and the movable base member, the helmet shield attaching mechanism can be operated easily and quickly.

[0226] Moreover, the provision of the actuating base member permits to simplify the structure of the helmet shield attaching mechanism providing at the same time a reliable structure able to guide in a secure and precise way the movements of the shield.

[0227] Furthermore, the provision of a separate actuating member permits to reduce the contact stresses between the stationary base member and the movable base member so as to reduce the wear of these components.

[0228] Lastly, the provision of the actuating base member does neither affect the dimensions of the attaching mechanism nor the dimensions of the helmet.

[0229] Regarding the embodiments of the helmet shield attaching mechanism and of the protective helmet described above, the person skilled in the art may, in order to satisfy specific requirements, make modifications to and / or replace elements described with equivalent elements, without thereby departing from the scope of the accompanying claims.

Claims

1. A helmet shield attaching mechanism comprising a shield attaching base member designed to be fastened to a shell of a protective helmet, and a shield having at least one side portion fastened to said shield attaching base member, the shield attaching base member comprising a stationary base member designed to be fastened to the shell of the protective helmet, and a movable base member coupled to said stationary base member and to the shield, said movable base member being movable with respect to the stationary base member, wherein said shield attaching base member further comprises an actuating base member pivotally connected to the stationary base member so that the actuating base member is adapted to rotate along a curved path and to abut against the movable base member thereby moving the movable base member with respect to the stationary base member during a rotation of the shield.

2. The helmet shield attaching mechanism according to claim 1, characterized in that the actuating base member is a separate element which is interposed between the stationary base member and the movable base member.

3. The helmet shield attaching mechanism according to claim 1, characterized in that the shield comprises a first guide portion connected to said movable base member, and a second guide portion connected to said actuating base member.

4. The helmet shield attaching mechanism according to claim 1, characterized in that the actuating base member is a lever having a first end pivotally connected to the stationary base member, and a second end connected to the second guide portion of the shield.

5. The helmet shield attaching mechanism according to claim 4, characterized in that the second end of the actuating base member is provided with a shoe slidably engaging an inner portion of a guiding track provided in the movable base member.

6. The helmet shield attaching mechanism according to claim 4, characterized in that the second end of the actuating base member is provided with coupling means engaged by the second guide portion of the shield through a groove provided in the guiding track.

7. The helmet shield attaching mechanism according to claim 4, characterized in that the second end of the actuating base member moves along a curved profile having a radius and a center, the center being centered on coupling means by means of which the actuating base member is pivotally connected to the stationary base member.

8. The helmet shield attaching mechanism according to claim 1, characterized in that a groove of a guiding track has a curved profile having a radius, corresponding to the distance between a first guide portion and a second guide portion of the shield, and a center coinciding with a center of the first guide portion of the shield once the shield is coupled to the movable base member.

9. The helmet shield attaching mechanism according to claim 1, characterized in that the stationary base member comprises first fastening means positioned at an upper portion and at a lower portion of the stationary base member.

10. The helmet shield attaching mechanism according to claim 1, characterized in that the stationary base member comprises second fastening means positioned at a front portion of the stationary base member.

11. The helmet shield attaching mechanism according to claim 1, characterized in that the stationary base member comprises first fastening means positioned at an upper portion and at a lower portion of the stationary base member and in that the stationary base member comprises second fastening means positioned at a front portion of the stationary base member, wherein each of said first fastening means and each of said second fastening means comprises at least one elongated track directed along an axis representing the travel direction of the movable base member with respect to the stationary base member.

12. The helmet shield attaching mechanism according to claim 11, characterized in that the movable base member comprises first guide seats positioned at a upper portion and at a lower portion of the movable base member, said first guide seats slidably engaging the first fastening means of the stationary base member, thereby allowing a translation movement of the movable base member with respect to the stationary base member along said axis.

13. The helmet shield attaching mechanism according to claim 1, characterized in that the movable base member comprises second guide seats provided at a front upper portion of a perimeter profile of the movable base member, said second guide seats engaging the second fastening means of the stationary base member, so as to work in combination with the first guide seats in guiding the translation movements of the movable base member with respect to the stationary base member.

14. The helmet shield attaching mechanism according to claim 1, characterized in that the movable base member comprises a coupling portion for coupling the movable base member to a first guide portion of the shield, said coupling portion consisting of a recess provided in the movable base member and having a profile designed to match an outer profile of the first guide portion.

15. The helmet shield attaching mechanism according to claim 1, characterized in that a bottom surface of a coupling portion projects from the inner surface of the movable base member to abut against the stationary base member so as to be slidably housed inside a first guide portion of the stationary base member.

16. The helmet shield attaching mechanism according to claim 15, characterized in that said first guide portion of the stationary base member has an elongated shape whose major axis extends along the axis, the first guide portion being delimited by two linear surfaces extending parallel to said axis wherein said linear surfaces are closed by a front curved surface and a rear curved surface.

17. The helmet shield attaching mechanism according to claim 1, characterized in that a first guide portion and a second guide portion of the shield are projecting portions provided at an inner surface of the shield, the first guide portion consisting of a cylindrical projecting portion and the second guide portion consisting of a projecting pin provided with a support member comprising at least one indentation, said at least one indentation corresponding to indentation provided at the internal surface of the groove of the guiding track.

18. A protective helmet comprising a shell and two helmet shield attaching mechanisms according to claim 1, and further comprising a first helmet shield attaching mechanism being applied on a left side portion of the shell and a second helmet shield attaching mechanism being applied on a right side portion of the shell.

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