WO1990004932A1

WO1990004932A1 - Device for securing a crash helmet

Info

Publication number: WO1990004932A1
Application number: PCT/FR1989/000567
Authority: WO
Inventors: Vittorio Bianchi
Original assignee: Atys S.A.
Priority date: 1988-11-04
Filing date: 1989-11-02
Publication date: 1990-05-17
Also published as: FR2638618A1; AU4623289A

Abstract

The device comprises a water-tight circuit having, on the two sides, of a check valve (2), on the one side a cavity (3) with flexible or mobile walls filled with a fluid (4), on the other side at least one unit forming a bladder (5, 5b) with flexible or mobile walls connected by at least one channel (6) to the check valve (2) and capable of being inflated by the fluid (4) coming from the cavity (3); the valve (2) normally checks the return of the fluid from the bladder (5, 5b) towards the cavity (3), but can be opened, the bladder (5, 5b) being secured to said object at a point where, when inflated, it rests on the object and said support in order to secure the object to the latter, while leaving the object free, when not inflated, in relation to its support. The fluid is a liquid, the volume of the liquid (4) contained in the circuit roughly corresponds to the volume inside the cavity (3) and the bladder (5, 5b) is designed in such a manner and secured to the object at a point such that, when inflated, it prevents the object from being removed from the support. The device is used in particular for retaining a movable object on a support, especially a protective accessory on said support, and more particularly a crash helmet on the head of a motor cyclist.

Description

Securing device for protective helmet

The present invention relates to a device for retaining a removable object on a support, in particular an accessory for protecting said support, as well as an accessory for protection, in particular a helmet, comprising such a device.

The invention relates in particular to a device for retaining an object on a support, comprising means which, in the service position, bear on both said object and said support. The invention relates in particular to a device for rete-, bare of protective accessories such as a helmet on the head of the person who wears it.

Many devices of the aforementioned type are known for retaining removable objects on a support, in particular protective accessories such as gloves, shoes, helmets: among the known and commonly used devices, there may be mentioned devices with discontinuous adjustment by buttons, snaps, strap and buckle, or continuously adjustable devices such as laces, straps, adhesive tapes (for example VELCRO tapes), elastic bands, etc. These various devices all have drawbacks, particularly if the object to remember is an accessory to protect the human body: some devices are too rigid and can injure, for example in the case of a helmet chin strap; others are bulky and do not allow to adapt easily to small objects or to small parts of the body. Still others, in particular elastic devices, do not resist a tearing force. Others finally, such as for example so-called full face helmets for motorcyclists, have a movable part around external pivots liable to break in the event of an impact, so that the helmet no longer holds, is removed, and ceases to protect the head of the motorcyclist. US-A-3,866,243 discloses a in the case of a helmet ^s' ystem helmet adjustment on the head comprising at least one chamber connected to a fluid source compres¬ sible. When a user places the helmet on his head, the latter comes into contact with the compressible fluid source, which is a reservoir, and drives the fluid from this reservoir into the chamber, a non-return valve preventing the return of the fluid from the chamber in the tank. The space intended to receive the head, inside the helmet, is thus permanently modified. Such a system has several drawbacks: the reservoir and the chamber - or the chambers - exert on the places of the head on which they are based respec¬ tively a certain pressure which can quickly become unbearable and which risks interfering with the circulation of blood . In addition, due to the compressibility of the fluid, the chambers do not retain the helmet on the head in the event of a fall or impact, so that the head is no longer prote¬ ged when it should be.

The system described in the aforementioned patent is therefore not capable of successfully undergoing the tearing resistance tests prescribed in particular by the standards for the approval of helmets of motorcyclists sold on the market: the helmet thus equipped must therefore be provided with a chinstrap whose drawbacks have been recalled above.

The object of the present invention is to remedy the drawbacks of known devices and to propose a device for retaining a removable object on a support, in particular an accessory for protecting said support, which does not injure, which resists the efforts of , which can easily adapt to objects or small parts of the body, which can obviously be very easily and quickly implemented and released, which does not contain any fragile element capable of breaking and ceasing to act in the event of shock, and that is economical.

The device for retaining a removable object on a support, in particular an accessory for protecting said support, targeted by the invention comprises a sealed circuit comprising, on either side of a non-return valve, on one side a bag with flexible or movable walls filled with a fluid, on the other at least one bladder with flexible or movable walls connected by at least one channel to the non-return valve, and capable of being inflated by the fluid coming of the pocket, the non-return valve normally preventing the return of fluid from the bladder to the pocket, but which can be opened, the bladder being fixed on said object in a place where, in the inflated state, it is supported on the object and said support to subject the object to the latter, while leaving, in the deflated state, the object free relative to the support.

According to the invention, this device is characterized in that the fluid is a liquid, in that the volume of the liquid contained in the circuit corresponds substantially to the interior volume of the bag, and in that the bladder is shaped in such a way and is fixed on the object in a place such that, in the inflated state, it prevents the object from being able to be removed from the support.

The liquid contained in the sealed circuit being incompressible, the bladder once inflated and in appμi on the object on the one hand and on its support on the other hand, has a constant volume and ensures a locking of the removable object on its support. Just open the non-return valve to unlock it. In the locked inflated position, it is not necessary for the bladder to exert any pressure on the object and / or the support or even be actually in contact with one or the other to ensure the abovementioned locking: no discomfort is therefore to be feared in the case of an accessory for protecting the human body.

The bladder can have any desired size and adapt to any shape of the object and its support. It has no sharp edges or rigid edges and cannot injure. The quantity of liquid sent into the bladder can be adjusted as desired, so that the object's retaining force can be very precisely adjusted so that the device resists tearing forces. Furthermore, the device is very easy to make and can be very economical.

According to a first version of the invention, the pocket with flexible or movable walls, after having been flattened to expel the liquid, is capable of resuming its initial inflated configuration while exerting a suction effect to facilitate the return of said liquid in the pocket.

This characteristic is likely to facilitate the release of the device and the object. Thus, for example, the walls of the pocket can be flexible and tend to return to their inflated position. One can also place a spring between two opposite walls of the pocket.

According to another aspect of the invention, the removable protective accessory, in particular of the human body, is characterized in that it comprises a retaining device according to the invention for retaining said- acces¬ soire in place. This accessory is in particular a helmet, in particular for a motorcyclist.

The helmet can thus be retained on the motorcyclist's head in the event of a fall or impact, and ensure full- protective function without causing any discomfort to it.

According to an advantageous version of the invention, the helmet comprises at least one bladder fixed to the carcass of the helmet under a flap pivotally mounted on said carcass and which, when inflated, pushes the flap under the lower jaw.

According to an advantageous version of the invention, a second flap is articulated at the free end of the first flap, and the second flap has lugs which project laterally in the direction of the axis of articulation thereof and which are respectively received in grooves of the helmet casing.

According to a preferred version of the invention, the wall of each groove on which the corresponding lug rests when the helmet is subjected to a tearing force comprises means for retaining the lug as long as said force l 'tearing. This groove is for example of a semi-hard plastic material in which the lug can penetrate and anchor.

The tearing forces exerted on the helmet, in particular in the event of a fall of the helmet wearer or of impact, are thus transmitted essentially to the carcass of the helmet and not to the sealed circuit containing the liquid. This circuit is thus not subject to significant overpressures, and can therefore be simple and economical.

Other characteristics and advantages of the invention will become apparent in the description below.

In the appended drawings, given by way of nonlimiting examples:

- Figure 1 is an overall perspective view of an adjustable device according to the present invention; - Figures 2A and 2B are respectively enlarged sectional views along II-II of Figure 1, the bladder being in the inflated state and in the deflated state;

- Figure 3 is an enlarged sectional view following III-III of Figure 1;

- Figure 4 is a sectional view along IV-IV of Figure 3;

- Figure 5 is an axial sectional .longitu¬ dinal view of an open type helmet with chin strap, provided with the device of Figure 1;

- Figure 6 is a view similar to Figure 5 of an integral type helmet with the device of Figure 1;

- Figure 7 is- a sectional view along VU-VU of Figure 6;

- Figure 8 is a partial sectional view sui¬ vant VIII-VIII of Figure 6, the helmet being in place on the head, the bladder being in the inflated state;

- Figures 9A and 9B are views similar to Figure 8 of a variant of the invention, the bladder actuating the flap being respectively in the inflated state and in the deflated state;

- Figures 10A and 10B are partial cross-sectional views along X-X in Figure XI, showing a particular embodiment of the bladder actuating the flap respectively in the inflated state and in the deflated state;

- Figure 11 is a partial sectional view sui¬ vant XI-XI in Figure 10A; - Figure 12 is a view similar to the - igure

10A of another embodiment of the invention, the second part not being shown for clarity of the figure;

- Figure 13 is a view similar to Figure 12 of another embodiment of the invention; - Figure 14 is a partial sectional view along XIV-XIV in Figure 13.

In the embodiment shown in Figures 1 to 4, the retaining device comprises a sealed circuit 1 comprising, on either side of a non-return valve 2 capable of being opened, on one side a pocket 3 with flexible walls filled with a liquid 4, for example water, on the other several (seven in the example shown) bladders 5 with flexible walls each connected by a channel 6 to the non-return valve 2 and capable of 'be inflated by the fluid 4 coming from the bag 3. All the elements of the sealed circuit 1 are intended to be fixed, in any known manner, for example by welding or by gluing, on any object , the bladder being fixed in a place where, in the inflated state, it bears on the object and on said support to secure the object to the latter.

These elements are made of any known flexible and tight material, elastic or not, for example a plastic material or rubber, in any known manner, for example by welding, by gluing, by dipping or the like.

The bladders 5 are, as shown in FIGS. 2A and 2B, produced respectively from two walls each cut from a flexible sheet, for example made of plastic; these two walls are assembled along their respective edges in a known manner, for example by gluing or welding. The channels 6 can be made in the same way, in one piece with the bladders 5, or be made for example by extrusion and connected ^ respectively to a bladder for example by gluing. The bag 3 can be made like the bladders 5.

As shown in detail in Figures 3 and 4, the non-return valve 2 is a plastic valve of known type, having a transverse slot 12 on the bottom 13 of an internal tubular element 14 projecting from the side facing the bladders 5 of a dirty transverse partition 15 of the valve 2.

The various elements 2, 3, 5, 6 are assembled in a known manner, for example by gluing or welding, to form the sealed circuit 1 which is fixed in one piece to the inner face of an object to be retained on its support.

When the user of the object presses the walls of the pocket 3, the slot 12 of the non-return valve 2 opens under pressure and the liquid 4 passes through the channels 6 and the bladders 5 which pass to the state inflated shown in Figure 2A. The bladders thus take support on the object and on the support by securing the object to it. In this state, the pressure of the liquid 4 on the side facing the bladders 5 of the partition 15 tends to close the slot 12, and the valve 2 opposes the return of the liquid 4 in the pocket 3.

If, on the other hand, the user pinches the longitudinal ends of the slot 12 between two fingers, he forces the slot 12 to open to let the liquid 4 return to the pocket 3 and bring the bladders 5 back to the degon¬ state flé, shown in particular in Figure 2B.

To facilitate the return of the liquid 4 from the bladders 5 and the channels 6 in the flexible bag 3, the latter is preferably capable of resuming, after having been flattened to expel the liquid 4, its initial swollen configuration while exerting a suction effect facilitating the return of the liquid 4 from the bladders 5 into the pocket 3. Thus, the walls of the pocket 3 can for example be flexible and tend to return to their inflated position. It is also possible to provide, in addition to this characteristic or as a variant of this, a spring 17 located between two opposite walls of the pocket (see FIG. 6), and / or a sponge disposed inside the poached. The volume of liquid contained in this circuit 1 corresponds substantially to the interior volume of the bag 3.

This volume is introduced into the circuit 1 so as to fill the bag 3 while the part of the circuit 1 located on the other side of the check valve 2 and compre¬ ing ^'bladders 5 and the channel 6 is substantially vacuo , the bladders 5 and the channels 6 then having their walls flattened. The volume of the bag 3 is of course at least equal to the total volume of the bladders 5 and the channels 6.

The presence of a small amount of compressible gas can possibly, in certain special cases, facilitate movement and avoid excessive rigidity of the part of the circuit 1 occupied by the liquid and the gas. In the embodiment shown in FIG. 5, the protective accessory is a helmet 18 of the so-called open type, which protects the forehead, the skull and the nape of the neck but not the figure. The helmet 18 comprises in particular a carcass 19, for example of rigid plastic material, internally covered with a flexible protective coating 20 such as a foam of plastic material. The helmet 18 is main¬ held by an adjustable chin strap 21 fixed on the carcass 19, and comprises, on its side intended to come into contact with the jaw, several bladders 5 which, by inflating, tighten the chin strap 21 on the jaw lower. The pocket 3, the non-return valve 2 and the channels 6 connecting the bladders 5 to the valve 2 are fixed to the coating 20 of the helmet 18, in any known manner, for example by gluing. The non-return valve 2 is of a type capable of being easily opened by the wearer and described below.

In the embodiment shown in Figures 6 to 8, the protective accessory is a helmet 22 of the so-called integral type which also protects the figure of the wearer of the helmet. This helmet 22 includes, like the helmet 18, a carcass 23, for example of rigid plastic material, internally covered with a flexible protective coating 24, for example of plastic foam. The carcass 23 has on its front face an opening 25 allowing vision, and on its lower face an opening 26 through which the helmet 22 is put on the head.

To retain the helmet 22 in place on the head, it comprises at the ^' periphery of the opening 26, several bladders with flexible walls 5 of the type described above, connected by channels 6 to a pocket 3 , filled for example with a liquid 4, by means of a non-return valve 2 capable of being opened. In the inflated state, the bladders 5 rest on the neck and on the lower jaw 32 and prevent the helmet from being removed (see FIG. 8).

As shown in FIG. 6, the pocket 3 can be fixed for example to the bottom of the helmet opposite the opening 26: thus, when the helmet 22 is put on, the upper part of the head presses the pocket 3 when the helmet is almost completely threaded, which allows both the adjustment of the position of the helmet on the head and the blocking of this on the neck and lower jaw 32 by adjusting the emptying of the pocket 3 and the filling of the bladders 5.

In this embodiment, the dimensions and the number of bladders 5 can be varied as desired, and have a very small number of elongated bladders such as 5a or 5b, or a larger number of smaller bladders which can cover all of them. or simply part of the periphery of the opening 26 (see FIG. 7).

Furthermore, the check valve 2 is of a type capable of being easily manipulated by the ^'wearer of the helmet, for example a known type of non-repre- sents valve ball kept on its seat by a spring, and provided with a needle such as 27 which can be pressed through a small opening 28 formed in the carcass 23 of the helmet, to separate the ball from its housing.

In the embodiment shown in Figures 9A and 9B, the carcass 23 of the integral helmet 22 has, on either side of the opening 26 and near the edge thereof, a rigid element acting as a flap 29 mounted so pivoting at 30 on the carcass 23. A flexible protective covering 31 is mounted on the flap 29. A bladder 5c is fixed on the carcass 23 under the flap 29. When it inflates, the bladder 5c is supported on the edge of the carcass 23 and pushes the flap 29 of which the covering 31 comes into contact with the lower jaw towards the inside of the helmet

32 to block the helmet 22 thereon (FIG. 9A). When the bladder is deflated, as shown in FIG. 9B, the flap 29 can be brought back against ^" the carcass 23 to release the opening 26 and allow the helmet to be put on the head and removed.

In the embodiment shown in Figures 10A, 10B and 11 to 13, a first flap 33 is articulated along an axis 34 on a base 35 fixed in a known manner quel¬ conch, for example by gluing, on the inner face of the carcass 23 of the helmet 22. The flap 33 carries on its face 36 facing the interior of the helmet, and at least near its free end, padding 37, for example of foam.

A second flap 38 is articulated along an axis 39 parallel to the axis 34 at the free end of the first flap 33. The second flap 38 has two parts arranged substantially in the extension of one another on the one hand and other of its axis of articulation 39 on the first flap

33: a first part 40 carries a padding 41 and is intended to be housed under the lower jaw of the wearer of the helmet 22 in the closed position of the flaps 33, 38 shown in FIG. 10A; a second part 42 pre- feels near its free end 43 of the lugs 44, 45 which project laterally in the direction of the axis of articulation 39 of the flap.

As shown in detail in Figure 11, the lugs 44, 45 are received respectively in grooves 46, 47 formed in respective walls 48, 49 of the base 35. The grooves 46, 47 are bent: they present a first part 46a, 47a substantially in the form of an arc of a circle centered on the axis 34 of the first flap 33; at their end close to the carcass 23 of the helmet, the grooves 46, 47 are extended by a second part 46b, * 47b bent in the direction of the axis 34.

. In the closed position of the flaps 33, 38 shown in particular in FIG. 10A, the two parts 40, 42 of the flap 38 are substantially in the extension of the grooves 46a, 47a, and form with the end part of the flap 33 a angle close to 90 °.

Thus, the direction of the grooves 46a, 47a and the arrangement of the pins 44, 45 are such that a tearing force exerted on the helmet 22 causes a reaction force of the lower jaw of the helmet wearer on the bead 41 (arrow FI ) which tends to push the pins in a direction (arrow F2) substantially perpendicular to that of the grooves 46a, 47a. According to a feature of the invention, the wall

46c, 47c of each groove 46a, 47a on which is supported (arrow F2) the lug 44, 45, corresponding when the helmet 22 is subjected to a tearing force (reaction force indicated by the arrow FI), comprises means for retaining the lug 44, 45 as long as the said effort lasts -, *. tearing. This wall 46c, 47c of the groove 46a, 47a is preferably made of a semi-hard plastic material in which the lug 44, 45 can penetrate and anchor, the second flap then being in the position shown in dashes and indicated by the reference 40a in FIG. 10A. When the lifting force has ceased, the semi-hard plastic material returns to its initial shape by its natural elasticity and replaces the lug 44, 45 corresponding in the respective groove 46a, 47a. Alternatively, the wall 46c, 47c may include a notch (not shown) which penetrate in the lug 44, 45 such notch should have a directed edge to ^'elbow 46b, 47b inclined and rounded to facilitate the output of the 'pin 44, 45 of said notch. In all cases, the stripping forces to which the helmet can be subjected are thus mainly transmitted to the walls 48, 49 and by these to the carcass 23 of the helmet, and only slightly apply the normal actuation means. flaps (see below): the helmet is thus firmly retained on the wearer's head in the event of a fall or impact, and fully exercises its protective function.

On the contrary, during the normal movement of opening the flaps 33, 38, in order to pass from the closed position of FIG. 10A to the open position shown. In FIG. 10B, the whole of the flap 38 is driven in a path. circular centered on the axis 34 (arrow F3), and the lugs 44, 45 slide naturally in the grooves 46a, 47a and slide on the walls 46c, 47c thereof. At the end of the race, the lugs 44, 45, arriving in the bent part 46b, 47b of the grooves 46, 47, rotate the second flap 38 relative to the first flap 33 to arrive in the fully open position of FIG. 10B. In the embodiment of FIGS. 10A and 10B., The flap 33 is secured to a piston 50 movable inside a cylinder 51 secured to the base 35 and therefore to the carcass 23 of the helmet. The cylinder 51 has for example the shape of a toric sector of axis coincident with the axis 34 of the first flap 33, and the piston 50 then has the shape of a circular plate whose edge has in a known manner a groove 52 receiving a seal 53.

The cylinder 51 communicates with the sealed hydraulic circuit through a valve, shown diagrammatically by the washer 54, and conduits (not shown). In known manner, the valve 54 is maintained in the closed position on the bottom 55 of the base 35 by a spring 56: when the pressure of the hydraulic circuit increases upstream of the valve 54, the latter opens and the liquid penetrates to the inside the cylinder 51 and pushes the piston 50 to close the flaps 33 and 38. A stopper 79 secured to the carcass 23 limits the stroke of the flap 33 in the closed position.

The valve 54 can be opened to empty the cylinder 51 by pressing on. the button 57 visible on the outer face of the carcass 23 of the helmet.

In the embodiment of FIG. 12, a flange 58 with a flexible wall capable of folding on itself controls the movements of the flap 33. Part of the wall of the flange 58 is fixed to the bottom 55 of the base 35 in the form of a cradle around the valve 54. Another opposite part of the wall is fixed to a cradle 80 of concave shape projecting from the flap 33. The flange 58 has a general C-shape both in its inflated situation shown in solid lines and in its substantially emptied situation represented in dashes.

In the embodiment of Figure 13, the flaps 33, 38 are placed manually in their closed position shown in the figure. The flap 33 carries on its underside facing the carcass 23 of the helmet a rack 59 in the form of a circular sector centered on the axis 34. The flap 33 is locked in its closed position by a pawl 60 which does not oppose movement of the flap 33 from its open position to its closed position.

As shown in Figure 14, the pawl 60 is pivotally mounted about an axis 61 which passes through walls 62, 63 integral with the base 35. A spring 64 which rests on a wall 65 of the base 35 which connects the walls 62, 63 presses the pawl 60 against the rack 59.

As shown in FIG. 14, the rack 59 preferably has a U-shaped section, the opening of the U being turned towards the pawl 60. The teeth of the rack are formed on the walls 70, 71 forming the branches of the U .

For its part, the pawl 60 has its toothed face which is the entire width of the rack 59. On the other hand, its curved end 69 has a width allowing it to pass between the two walls 70, 71 of the rack 59 so as not to interfere withdrawal thereof.

The flaps 33, 38, the base 35 and its walls 48, 49, the rack 59, the pawl 60, etc. are preferably made of molded plastic and are of course correctly sized, ribs, reinforced to have the necessary resistance. . The hollow elements have the undercuts necessary to allow molding.

The helmet described preferably has two flaps 29, 33 on either side of the face. It could include a single shaped flap surrounding the chin and the jaw of the wearer of the helmet. The two-flap system 33, 38 described above with the lugs 44, 45 and the grooves 46, 47 for guiding and blocking the flap 38 thus makes it possible to transmit to the carcass of the helmet most of the reaction force of the jaw on the flap 38 to an effort to tear off the helmet. Only a small part of this force is

•• * _ transmitted to the piston / cylinder assembly 50, 51 or to the flange 58, so that the liquid which is contained therein is not subjected to significant pressures likely to cause problems of resistance and / or tightness of these elements. The same is true for the mechanical rack system.

The helmet according to the invention is thus able to resist, with simple and inexpensive means, the detachment tests prescribed by the helmet approval regulations before they are made available to the public.

Of course, the invention is not limited to the embodiments which have just been described, and many changes and modifications can be made to them without departing from the scope of the invention.

Thus, the fluid can be a liquid other than water, for example an antifreeze liquid, of the glycol type, or a hydraulic liquid, or even an antiseptic liquid in the event of a circuit breakage during an accident. This fluid can comprise a small volume of any gas compatible with the liquid and the material of the components of the sealed circuit 1, such as air, nitrogen or the like.

Likewise, the non-return valve can be replaced by a valve of any type which is closed to maintain the fluid in the channels and the bladders, and which is opened to allow the return of the fluid in the pocket. .

The bladders can have any shape and dimensions, in particular for example a concave shape or an annular shape, have flexible walls, even elastic in certain cases, or on the contrary rigid walls movable with respect to each other. The sealed circuit 1 can be used under any conditions and with any jobjet other than those described, and its elements, in particular the bag 3 and the bladders 5, can be covered by any flexible sheet which comes into contact. with the skin. ^"

The system of the two flaps 33, 38, the guiding of these by the pins 44, 45 and the ribs 46, 47, the cylinder 51 and piston 50 assembly, the flange 58, the rack 59 and the pawl 60, can of course be replaced by equivalent systems fulfilling the same functions to achieve the same result.

Claims

CLAIMS 1. Device for retaining a removable object on a support, in particular an accessory for protecting said support, this device comprising a sealed circuit (1) comprising, on both sides of a non-return valve ( 2, 34), on one side a pocket (3) with flexible or movable walls filled with a fluid (4), on the other at least one bladder element (5; 5a. 5b; 5c; 50, 51 ; 58) with flexible or movable walls connected by at least one channel (6) to the non-return valve (2, 34) and capable of being inflated by the fluid (4) coming from the pocket (3), the non-return valve ¬ return (2, 34) normally prohibiting the return of fluid from the bladder (5; 5a; 5b; 5c; 50, 51; 58) towards the pocket (3), but being able to be opened, the bladder (5; 5a; 5b; 5c; 50, 51; 58) being fixed on said object in a place where, in the inflated state, it bears on the object and said support to secure the object to the latter, while leaving, at deflated state, free object by ra port to the support, characterized in that the fluid is a liquid, in that the volume of the liquid (4) contained in the circuit (1) corresponds substantially to the interior volume of the pocket (3), and in that the bladder ( 5; 5a; 5b; 5c; 50, 51; 58) is shaped in such a way and is fixed on the object in a place such that, in the inflated state, it prevents the object from being able to be removed from the support.

2. Device according to claim 1, characterized in that the pocket with flexible or movable walls (3), after having been flattened to expel the liquid (4), is capable of resuming its initial inflated configuration while exerting an effect of suction to facilitate the return of said liquid (4) in the pocket (3).

3. Device according to claim 2, characterized in that the walls of the pocket (3) are flexible and tend to return to their inflated position.

4. Device according to one of claims 2 or 3, characterized in that an element acting as a spring (1) is located between two opposite walls of the pocket (3).

5. removable protective accessory, in particular of the human body, characterized in that it comprises a retaining device according to one of claims 1 to 6 for retaining said accessory in place.

6. removable protective accessory according to claim 5, characterized in that this accessory is a helmet (18, 22), in particular of a motorcyclist. _< -

7. Helmet according to claim 6, characterized in that this helmet (18) is of the open type, provided with a chin strap (21), and in that the chin strap (21) has, on its side intended to come in contact with the lower jaw (32), several bladders (5) which, by swelling, tighten the chin strap (21) on the lower jaw (32).

8. Helmet according to claim 6, characterized in that this helmet (22) is of the integral type and comprises, at the periphery of the opening (26) allowing the helmet (22) to be put on the head, several bladders (5, 5a, 5b) which, by inflating, secure the helmet (22) on the neck and / or the lower jaw (32).

9. Helmet according to claim 8, characterized in that this helmet (22) comprises at least one - bladder (5c; 50, 51; 58) fixed to the carcass (23) of the helmet (22) under a flap (29 , 33) pivotally mounted on said carcass (23), and. which by swelling pushes the flap (29, 33) under the lower jaw (32).

10. Helmet according to claim 9, characterized in that the flap (33) is integral with a piston (50) movable inside a cylinder (51) integral with the carcass (23) of the helmet (22 ).

11. Helmet according to one of claims 9 or 10, characterized in that the flap (33) comprises means which, in the inflated position of the bladder (50, 51; 58) cooperate with means complementary to the helmet (22 ) to transmit to the carcass of the helmet most of the sudden tearing forces to which the helmet (22) may be subjected without opposing the usual movements of opening and closing of the flap (33).

12. Helmet according to claim 11, characterized in that a second flap (38) is articulated at the free end of the first flap (33).

13. Helmet according to claim 12, characterized in that the second flap (38) comprises guide means (44, 45) which cooperate with complementary guide means (46, 47) of the carcass (23) of the helmet (22) to guide the second flap (38) in its movements.

14. Helmet according to claim 13, characterized in that the second flap (38) has two parts (40, 42) arranged substantially in the extension of one another on either side of the axis d hinge (39) of the second flap (38) on the first flap (33), a first part (40) which carries a padding (41) and is intended to be housed under the lower jaw of the wearer of the helmet (22) when the bladder (50, 51; 58) is inflated, and a second part (42) which carries the guide means (44, 45).

15. Helmet according to one of claims 13 or 14, characterized in that <ιue the second flap (38) comprises lugs (44, 45) which project laterally in the direction of the axis of articulation (39) thereof and which are respectively received in grooves (46, 47) of the carcass (23) of the helmet (22).

16. Helmet according to claim 15, characterized in that the direction of the parts (46a, 47a) grooves (46, 47) which correspond to the closed position of the flaps (33, 38) and the arrangement of the pins (44, 45) are such that a tearing force exerted on the helmet tends to push the pins ( 44, 45) in a direction (F2) substantially perpendicular to that (F3) of the grooves (46, 47).

17. Helmet according to one of claims 15 or 16, characterized in that the wall (46c, 47c) of each groove (46a, 47a) on which the lug (44, 45) corresponding when the helmet rests (22) is subjected to a tearing force comprises means for retaining the lug (44, 45) as long as said tearing force lasts.

18. Helmet according to claim 17, characterized in that said wall (46c, 47c) of the groove (46a, 47a) is made of a semi-hard plastic material into which the lug (44, 45) can penetrate and s 'anchor.

19. Helmet according to claim 17, characterized in that said wall (46c, 47c) has a notch with rounded edges.

20. Helmet according to one of claims 6 to

19, characterized in that the flexible pocket (3) is fixed to the bottom of the helmet (18, 22) to come into contact with the upper part of the head when the helmet is put on the head.