A safety device

Abstract

A clamping device (1) for selectively clamping a portion (15) of a strap (12) in response to an increase in the strap tension, the locking device comprising a base element (2) having a first clamping surface (6); a spring element (8) having a second clamping surface (10) and mounted with respect to the base element so that the first and second clamping surfaces face, and are spaced apart from one another; an elongate element (12) which is fixed in place at a first end (13) thereof, and has a first portion (14) near the first end which has a first tensile modulus, and a second portion (15), further from the first end than the first portion, which has a second tensile modulus, which is higher than the first tensile modulus, and wherein the second portion (15) of the elongate element (12) is positioned between the first and second clamping surfaces (6, 10); and a guide component (16) having a guide surface (17) over which the elongate element (12) passes, wherein, when the elongate element is pulled in a first direction, the elongate element exerts a force on the guide surface (17), which tends to deflect the first clamping (6) surface towards the second clamping surface (10).

Description

[0001] A Safety Device

[0002] This invention relates to a safety device, and in particular concerns a device for selectively locking elongate elements, such as straps, which are used to secure protective equipment to a user’s body.

[0003] Background

[0004] Wearable safety equipment such as padding must often be secured tightly to the body using elongate elements such as straps to provide maximum protection to the wearer. Straps are commonly used with safety equipment including helmets, knee and elbow pads, wristguards and spineboards. Fastening devices like straps must be tensioned to fasten devices securely to a wearer. However, straps that tensioned to provide a secure fit often cause discomfort and movement restriction to the wearer. A wearer may secure equipment relatively loosely for comfort and ease of movement during normal use, but a loose fit of this kind will often not secure safety equipment adequately, leading to increased risk of injury in the event of an accident.

[0005] Whilst safety devices are worn over extended periods, their protection is typically only required during specific events such as a fall or vehicle crash.

[0006] It is therefore advantageous to provide a device to fasten equipment to a user with sufficient “slack” for adequate comfort and freedom of movement, whilst also providing means to selectively reduce the available slack from securing straps to provide a secure fit when required. The addition of such a device to existing equipment should also not add significant cost and weight. Current devices such as that disclosed in EP2496102B1 , offer a complex, bulky, and expensive means by which to adjust the length of straps in a protective helmet. This document discloses a device with a spool and means to wind / unwind a strap to achieve a desired length, and after an external push-button is released block the winding / unwinding to prevent further changes to strap length.

[0007] It is an object of the invention to provide an improved mechanism for selectively locking straps.

[0008] Summary of the Invention

[0009] One aspect of the present invention provides a selective clamping device according to claim 1.

[0010] Further features of the invention are set out in the dependent claims.

[0011] In order that the present disclosure may be more readily understood, embodiments thereof will now be described, with reference to the accompanying drawings, in which:

[0012] Figures 1 and 2 show a locking device according to a first embodiment of the invention.

[0013] Figure 3 shows a locking device according to a second embodiment of the invention, installed in a helmet.

[0014] Figure 4 shows the locking device of figures 1 and 2 in a deformed configuration.

[0015] With reference to figures 1 and 2, the principal features of a first locking device 1 embodying the invention are shown.

[0016] The first locking device 1 includes a base element 2. In the example shown the base element 2 comprises a rectangular sheet of a sturdy material, such as metal or plastic. The base element 2 has a first end 3 and a second end 4. On a first side 18 of the base element 2, near its second end 4, there is a raised feature 5. In this example the raised feature 5 takes the form of a rib which extends across the width of the first side 18 of the base element 2.

[0017] Also on the first side 18, there is a first clamping surface 6. In this example, the first clamping surface 6 is positioned between the raised feature 5 and the second end 4. In the example of figures 1 and 2 the first clamping surface 6 occupies all or substantially all of the region between the raised feature 5 and the second end 4, although this is not essential and in other examples the first clamping surface 6 occupies only a part of this region. The first clamping surface 6 may have different surface topology characteristics to the remainder of the first side 18 of the base element 2. In the example shown in figure 1 , the first clamping surface 6 has a number of protruding barbs 7. These barbs 7 protrude from the first clamping surface 6, preferably in a direction which has a component towards the first end 3 of the base element 2.

[0018] In preferred embodiments the height of the barbs 7 is such that they do not protrude above the level of the raised feature 5, with respect to the first side 18 of the base element 2.

[0019] The first clamping surface 6 may alternatively have a high-friction surface finish, coating or geometry, such as particulates imbedded or bonded to the surface, a textured pattern cut into the surface, sandpaper of a suitable roughness, rubber or rubberdike polymer, an array of microhooks, or a textured metallic coating.

[0020] Preferably, over all or substantially all of the first side 18 of the base element 2, between the first end 3 and the raised feature 5, the first side 18 is smooth or substantially smooth, and is also preferably free from protruding features.

[0021] The first locking device also includes a spring element 8. In the example shown, the spring element 8 is a cantilever spring, fixed at a first end 9 such that it extends parallel or generally parallel with the base element 2.

[0022] In this example the first end 9 of the spring element 8 is fixed with respect to the first end 3 of the base element 2. The spring element 8 also has a second end 11 , which is a free end. In the embodiment of figures 1 and 2 the base element 2 and spring element 8 are integrally formed, for instance by being moulded from the same polymer or metal. A connecting element 20 extends between the first ends 3, 9 of the base element 2 and spring element 8.

[0023] The base element 2 and spring element 8 may be formed from different components, which are formed and then connected together in any suitable way, e.g. by welding or adhesive. In such embodiments the base element 2 and spring element 8 may be formed from different materials.

[0024] In the example shown the spring element 8 is generally rectangular, although this need not be the case. The spring element 8 has a first side 19 that faces towards the base element 2. The first side 19 of the spring element 8 has a second clamping surface 10 near the second end 11 . In the first example, the second clamping surface 10 is a raised section which protrudes from the first side of the spring element 8. The second clamping surface 10 faces, and is spaced apart from, the first clamping surface 6. The second clamping 10 surface may be fabricated from the same material as the spring element 8.

[0025] The second clamping surface 10 may comprise a high-friction surface finish, coating or geometry, similar to that of the first clamping surface 6 (or to the other examples discussed above in relation to the first clamping surface). Optionally, the second clamping surface 10 may have surface characteristics that match or interface with those of the first clamping surface 6. For example, some or all of the second clamping 10 surface may have an inverse or substantially inverse surface relief to that of the first clamping surface 6, such that the two surfaces may fit together with substantially full contact if pressed together.

[0026] In some embodiments, one of the first and second clamping surfaces 6, 10 may be smooth or substantially smooth. The smooth surface may not have a high coefficient of friction with the second portion 15 of the elongate element 12. In such embodiments, the smooth surface acts to press the second portion 15 of the elongate element 12 against the other one of the clamping surfaces 6, 10.

[0027] A flexible elongate element 12 extends between the base element 2 and the spring element 8 and is fixed at a first end 13, which in this example is located at or near the first end 9 of the spring element 8 and the first end 3 of the base element 2. In the example shown the first end 13 of the elongate element 12 is fixed to the connecting element 20, although this is not essential.

[0028] In the example shown the elongate element 12 has a width which is the same as, or similar to, the width of the base element 2 and the spring element 8. In examples where the base element 2 and spring element 8 are not of constant width, the elongate element 12 preferably has a width which is the same as, or similar to, that of the first clamping surface 6.

[0029] The elongate element 12 preferably takes the form of a flexible strap or ribbon.

[0030] The elongate element 12 extends beyond the second end 4 of the base element 2 and the second end 11 of the spring element 8.

[0031] In the example of figures 1 and 2, the elongate element 12 has a first portion 14 and a second portion 15. The first portion 14 of the elongate element 12 is positioned closer to the first end 13, and preferably extends from the first end 13. The second portion 15 is positioned further from the first end 13 than the first portion 14.

[0032] The first portion 14 has a first tensile modulus, which is less than the tensile modulus of the second portion 15.

[0033] In preferred embodiments the first portion 14 is formed from an elastic material, which exhibits a relatively large extension when subject to relatively limited force. For example, the elastic material may have a tensile modulus of 6-12 MPa. The second portion 15 is preferably relatively inextensible, requiring significantly more force to deform. The second portion 15 may have a tensile modulus of approximately 2000 MPa, and may be formed from a robust webbing material, such as woven nylon or polyester. Stretching of the first portion 14 allows for extension of the elongate element 12 under a relatively low tensile load T. Tension T applied beyond the elastic limit of the first portion 14 results in minimal further extension of the elongate element 12.

[0034] In preferred embodiments, when the elongate element 12 is at rest, i.e. not under any tensile load, a part of the second portion 15 is positioned between the first and second clamping surfaces 6, 10. It is also preferred that, when the first portion 14 reaches its elastic limit, a part of the second portion 15 is positioned between the first and second clamping surfaces 6, 10.

[0035] A guide component 16 rigidly adjoins, or is integrally formed with, the spring element 8 at the second end 11. In this example the guide component 16 includes an aperture 21 through which the elongate element 12 passes. A side of the aperture 21 comprises a guide surface 17. The elongate element 12 passes over the guide surface 17, such that it then extends in a direction which has a component towards the plane of the base element 2. It will be understood that the elongate element 12 therefore engages the guide surface 17 such that tension T in the elongate element 12 will exert a force on the guide component 16, where this force has a component F towards the plane of the base element 2.

[0036] The skilled person will realise that the guide surface 17 may vary in orientation depending on the anticipated path of the elongate element 12. In the example shown the guide surface 17 comprises at least part of the side of the aperture 21 which lies furthest from first end 9 of the spring element 8. In this example the side of the aperture 21 that forms the guide surface 17 is generally straight, and has a length which is at least equal to the width of the elongate element 12, so that the elongate element 12 can contact the guide surface 17 across its width.

[0037] In the example shown the guide component 16 comprises a planar or substantially planar element which has a free end [ref] and protrudes at the second end 11 of the spring element 8, at an angle to the first side 19 of the spring element 8, such that the free end [] lies closer to the plane of the base element 2 than the point at which the guide component 16 joins the spring element 8. The aperture 21 is formed through this planar element. In preferred embodiments, when the spring element 8 is at rest and not under any deflection, the elongate element 12 extends from its first end 13, and passes over the guide surface 17, along a plane which passes between, but preferably does not contact, the clamping surfaces 6, 10. In this configuration the region of the elongate element 12 between its first end 13 and the guide surface 17 is at an angle which is parallel or substantially parallel with the clamping surfaces 6, 10.

[0038] When a tension T is applied to the elongate element 12, the guide component 16 imparts the resulting component F of the force to the spring element 8, which will lead to deflection of the spring element 8 towards the base element 2. With sufficient tension T, the spring element 8 deforms into a deformed configuration (shown in figure 4), in which the first clamping 6 surface and the second clamping surface 10 are close enough to securely engage the elongate element 12 therebetween. As mentioned above, a part of the second portion 15 of the elongate element will be gripped between the clamping surfaces 6, 10, and the first portion 14 of the elongate element 12 cannot extend further. In this configuration, therefore, the length of the elongate element 12 that protrudes from the clamping device 1 , which comprises the relatively inextensible second portion 15, cannot substantially increase any further.

[0039] The tensile moduli and lengths of the portions 14, 15 of the elongate element 12 may be chosen to alter the amount of extension of the elongate element 12 that occurs before imparting sufficient force F to the guide surface 17 for the spring element 8 to reach its deformed configuration.

[0040] In use, the amount of deflection of the spring element 8 is dependent on the rate or acceleration at which the elongate element 12 is extended. Extension of the elongate element 12 will occur due to tensile load applied to the elongate element 12, causing it to stretch. The elongate element 12 will stretch approximately elastically until the elastic limit of the first portion 14 is reached, or until it is clamped by the clamping surfaces 6, 10.

[0041] In practice, the clamping device 1 permits a greater amount of extension of the elongate element 12 when a lower force is applied to the elongate element (and hence when acceleration of the elongate element 12 is lower), and only a lesser amount of extension of the elongate element when a larger force is applied to the elongate element 12 (and hence when acceleration of the elongate element 12 is higher), before the spring element 8 reaches its deformed configuration. As a result, if a user pulls on the elongate element 12 with a relatively low force, a first length of the elongate element 12 can be withdrawn from the clamping device 1 before the elongate element 12 is clamped between the clamping surfaces 6, 10. However, if the user pulls on the elongate element 12 with a higher force, a second length of the elongate element 12 can be withdrawn from the clamping device 1 before the elongate element 12 is clamped between the clamping surfaces 6, 10, where the second length is less than the first length.

[0042] It is envisaged that the clamping device 1 may be used to secure protective safety equipment to a user.

[0043] The device 1 allows the elongate element 12 to reach a relatively long extension when the user is donning protective equipment (and therefore extends the elongate element 12 relatively slowly). The wearer can easily don the protective equipment, and the elasticity of the first portion 14 of the elongate element 12 ensures a comfortable, non-restrictive fit during normal wear.

[0044] Conversely, under faster rates of extension of the elongate element 12 (for example during a vehicle crash) only a relatively short portion of the elongate element 12 will extend from the clamping device 1 before the spring element 8 reaches its deformed configuration and clamps the elongate element 12. This ensures that the protective equipment is tightly secured to the wearer during scenarios such as vehicle crashes or falls (where a tight, securely fit is most crucial and comfort is of relatively diminished importance).

[0045] Once the spring element 8 has reached its deformed configuration and has clamped the elongate element, further significant extension of the elongate element 12 may not occur until the tensile force on the elongate element 12 is reduced such that the clamping surfaces 6, 10 no longer engage the elongate element 12. Once the tension is sufficiently reduced, the clamping surfaces 6, 10 will release the elongate element 12, which is again free to extend. One example use case for the clamping device may be used to provide means to fasten a helmet 31 to a wearer with sufficient slack / elasticity for adequate comfort and movement freedom, whilst also providing means to selectively remove slack from helmet straps 32 to provide a secure fit when required. This embodiment of the invention is illustrated in Figure 3.

[0046] Whilst the clamping device 1 is depicted in the rear of the helmet 31 , it should be noted that the clamping device 1 may be positioned anywhere suitable within the helmet 31 . In the example shown the helmet 31 had conventional straps 32, which extend from each side of the helmet 31 and are of a suitable length to pass under the user’s chin when the helmet 31 is worn.

[0047] The elongate element 12 must connected to the helmet straps 32 such that tension in the straps 32 is transferred to the elongate element 12. In a preferred example, a part of a strap 32 of the helmet forms, or is connected securely to, the second portion of the elongate element.

[0048] The clamping device 1 must be positioned and oriented within the helmet 31 such that the trajectory of the elongate element 12 exerts a force on the spring element 8, via the guide surface 17 of the guide component 16, in a direction to deflect the spring element 8 towards the base element 2, as discussed above.

[0049] Figure 3 shows an embodiment of the clamping device 1 where the first portion 14 of the elongate element 12 is a metal extension spring. It should be noted that this spring schematically represents the relatively extensible first portion 14 of the elongate element 12, and that this first portion 14 may take any suitable form, for instance a cord, strip or ribbon of an elastic material, e.g. as shown in figures 1 and 2. Indeed, for the example of a helmet, it is envisaged that the overall dimensions of the clamping device 1 should be as small as possible, and so length of an elastic material may be preferable to an extension spring.

[0050] In this example, there may be one or more clamping devices 1 in positioned in the helmet 31 , each clamping device being connected to, or integrally formed with the helmet straps 32 via a respective elongate element 12. Preferably, the one or more helmet straps 32, themselves, form the relatively inextensible second portions of one or more elongate elements 12. Alternatively, the one or more helmet straps 32 may be integrally joined to the elongate elements 12 of one or more clamping devices 1.

[0051] When donning of the helmet 31 , and during normal use of the helmet 31 , the rate of extension of the first portion 14 of the elongate element 12 or straps 32 will occurs at a relatively slow rate. Therefore, under these conditions, the spring element 8 does not reach its deformed configuration and thus allows a relatively large amount of extension of the elongate element 12. Conversely, when the elongate element 12 is extended at a faster rate (for example under conditions of a crash or fall) sufficient force F is imparted into the spring element 8 such that it reaches its deformed configuration more rapidly and traps the elongate element 12 between the clamping surfaces 10, 6. This prevents further extension and therefore ensures that the helmet 31 is secured to the wearer’s head tightly and securely during these circumstances.

[0052] It is envisaged that, for a helmet 31 which uses one or more clamping devices 1 embodying the invention, it may be possible to avoid the need for a clip, buckle or similar which joins two separate lengths of strap under the wearer’s chin. Instead, there can be a single strap (which may be of unitary construction, although this is not essential) which passes under the wearer’s chin. Under low rates of extension, this strap can be stretched by a sufficient amount for the helmet to be put on easily, and will then retract to give a secure and comfortable fit during normal wear.

[0053] Avoiding a clip or buckle will be preferred by many users. Clips or buckles can be uncomfortable during wear, and may be difficult to operate for children or users with reduced dexterity, or by users wearing gloves in colder weather.

[0054] In the example shown in figure 3 the clamping device 1 is positioned in a rear portion of the helmet 31 . The skilled reader will appreciate that, in this example, the elongate element 12 and / or straps 32 will be guided from the clamping device in a suitable way to the desired locations on the helmet. In other examples, a clamping device may be positioned on one side of the helmet, to simplify its connection to a strap that extends from that side of the helmet. In some examples two clamping devices are provided, one on each side of the helmet, with each clamping device being connected to a strap on the respective side. The skilled reader will understand that the or each clamping device can be placed in any suitable position.

[0055] The skilled person will understand that the clamping device 1 may be used in conjunction with a variety of wearable equipment including but not limited to wrist guards, knee pads, and elbow pads. Consistent with the embodiments previously discussed, the clamping device 1 can offer means to secure a range of items comfortably and flexibly to a wearer with the ability to restrict flexibility as the acceleration of the item (with respect to the wearer) increases beyond a threshold.

[0056] In yet another embodiment of the invention, the clamping device 1 is deployed in a safety belt, the skilled reader will appreciate that greater extension of the elongate element may be required for a comfortable and unrestrictive fit in this embodiment, as compared to (for example) use of the clamping device in a helmet. A lengthening of the clamping device 1 along with the first portion 14 of the elongate element 12 would allow for greater extension of the elongate element 12. Preferably, the material (e,g, webbing) of the safety belt itself forms, or is joined securely to, the second portion 15 of the elongate element 12. There may also be multiple clamping devices 1 (for example one at each end of each safety belt). Consistent with previously discussed embodiments, the clamping device permits relatively long extension of the elongate element 12 under lower rates of extension (for example when the user is putting on the seat belt, or leaning forward during normal use). At higher rates of extension of the elongate element 12 (for example during a vehicle crash), the device permits very little extension and thus secures the user in position.

[0057] In the discussion above the clamping device comprises a base element and a spring element. It is not necessary for the spring element to be more flexible, or prone to deformation, than the base element. These terms are used to designate that the spring element is arranged to deform primarily during use. The skilled reader will understand that the base element may be secured to a larger object (such as part of a helmet), so that it in use it will not deform to a significant extent, whereas the spring element is arranged so that it has a free end, which is not secured to any other object in a way that will significantly prevent it from deflecting towards the base element. In preferred examples, the spring element is more flexible than the base element, i.e. it can be deflected towards the base element under a lower force than the base element can be deflected towards the spring element.

[0058] In some examples the base element and spring element may be formed from the same material, and may be formed integrally. In the example shown in figures 1 and 2, the spring element 8 is thinner than the base element 2, in a direction perpendicular to the plane of the base and spring elements 2, 8. In other embodiments, the spring element may have a width that is less than that of the base element, over some or all of its length. In some examples there is a portion of the spring element, between its first end 9 and the second clamping surface 10, that has a reduced width, thus making it easier to deflect the spring element towards the base element.

[0059] In further examples some or all of the spring element is formed from a different material from the base element. In such examples it is preferred that the spring element is formed from a material that is more flexible than the material from which the base element is principally formed.

[0060] In embodiments of the invention at least one of the first and second clamping surfaces has a surface which has one or more protrusions, or is otherwise textured or roughened, as discussed above, such that it will have a relatively high coefficient of friction with the second portion of the elongate element. Alternatively, or in combination with this, one or both of the first and second clamping surfaces may be formed from a material which is smooth or substantially smooth but which will have a relatively high coefficient of friction with the second portion of the elongate element, such as a surface formed from a rubber material.

[0061] In preferred embodiments of the invention, the coefficient of friction between at least one of the clamping surfaces and the second portion of the elongate element is at least 0.75.

[0062] In the examples shown above the elongate element takes the form of a strap or ribbon, which has a width that is much greater than its depth. However, this is not essential, and the elongate element may take the form of a cord or similar, which has a width of comparable size to its depth (although such configurations may not be preferred, as it will be more difficult to clamp and arrest the motion of a cord effectively.

[0063] It should also be noted that the cross-sectional shape of the elongate element does not need to be the same along its length. For instance, in some examples the elongate element may have a clamping region, which is the region that will be between the clamping surfaces when the spring element is in its deformed position, where the clamping region takes the form of a strap or ribbon having a width that is much greater than its depth. However, on one or both sides of the clamping region, the elongate element may take a different form, for instance that of a cord or similar.

[0064] In the examples above the elongate element has a first portion 14, which has a first tensile modulus and is closer to the fixed first end 13 of the elongate element 12, and a second portion 15, which has a second, higher tensile modulus and is further from the fixed first end 13. However, this does not exclude the presence of other regions or portions of the elongate element 12. For instance, there may be a third portion (not shown), which is positioned between the fixed end 13 and the first portion 14. This third portion may be relatively inelastic, having a higher tensile modulus than the first portion. Having a third portion of this kind may assist in fixing the elongate element securely to the other components of the clamping device.

[0065] Alternatively, the third portion may be more elastic than the first portion (i.e. have a lower tensile modulus). Including a third portion of this kind may allow a controlled amount of additional extension when tension is applied to the elongate element.

[0066] Further portions, having any required amount of elasticity, may be provided in any suitable locations, for instance between the first and second portions, or further from the fixed end than the second portion.

[0067] The invention provides a clamping device, as defined in the appended claims, in isolation, and also provides safety devices which include such a clamping device. The skilled reader will appreciate that clamping devices and safety devices embodying the invention will provide relatively simple and robust arrangements for selectively gripping an elongate element, that will find use in many different safety devices.

[0068] When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

[0069] The invention may also broadly consist in the parts, elements, steps, examples and / or features referred to or indicated in the specification individually or collectively in any and all combinations of two or more said parts, elements, steps, examples and / or features. In particular, one or more features in any of the embodiments described herein may be combined with one or more features from any other embodiment(s) described herein.

[0070] Protection may be sought for any features disclosed in any one or more published documents referenced herein in combination with the present disclosure.

[0071] Although certain example embodiments of the invention have been described, the scope of the appended claims is not intended to be limited solely to these embodiments. The claims are to be construed literally, purposively, and / or to encompass equivalents.

[0072] Preferred features of the invention are set out in the following clauses:

[0073] 1 . A clamping device for selectively clamping a portion of a strap in response to an increase in the strap tension, the locking device comprising: a base element having a first clamping surface; a spring element having a second clamping surface and mounted with respect to the base element so that the first and second clamping surfaces face, and are spaced apart from one another; an elongate element which is fixed in place at a first end thereof, and has a first portion near the first end which has a first tensile modulus, and a second portion, further from the first end than the first portion, which has a second tensile modulus, which is higher than the first tensile modulus, and wherein the second portion of the elongate element is positioned between the first and second clamping surfaces; and a guide component having a guide surface over which the elongate element passes, wherein, when the elongate element is pulled in a first direction, the elongate element exerts a force on the guide surface, which tends to deflect the first clamping surface towards the second clamping surface. The clamping device of clause 1 , wherein one or both of the clamping surfaces has a coefficient of friction with the second portion of the elongate element of at least 0.75. The clamping device of clause 1 or 2, wherein one or both of the clamping surfaces comprises a plurality of protrusions to engage the second portion of the elongate element. The clamping device of any previous clause, wherein one or both of the clamping surfaces comprises a high friction coating or finish. The clamping device of any previous clause, wherein the clamping surfaces have complementary or substantially complementary surface profiles. The clamping device of any previous clause wherein one of the base element or spring element comprise a raised feature, protruding from a surface thereof that faces towards the other one of the base element and spring element, wherein the first or second clamping surface is between the raised feature and the free end of the one of the base element or spring element. The clamping device of clause 6, wherein one of the base element or spring element has one or more protrusions which protrude from the first or second clamping surface, and wherein the raised feature protrudes above the surface of the one of the base element or spring element by a greater distance than the protrusions. The clamping device of any previous clause, wherein the guide component comprises an enclosed loop, through which the elongate element passes. The clamping device of any previous clause, wherein the spring element is a cantilever spring. The locking device of any previous clause, wherein the spring element is a leaf spring. The locking device of any previous clause, wherein the spring element is a coil spring. The clamping device of any previous clause, wherein the spring element and the base element are joined together. The clamping device of clause 12, wherein the base element and spring element each have a first end and a second end, and wherein the base element and spring element are joined together at respective first ends thereof. The clamping device of any previous clause, wherein the elongate element comprises a third portion, the third portion having a third tensile modulus. The clamping device of clause 14, wherein the third tensile modulus is lower than the first tensile modulus. The clamping device of any previous clause, wherein the guide component is a part of the spring element. The clamping device of any previous clause, wherein the first portion of the elongate element is an extension spring. The clamping device of any previous clause, wherein the first portion of the elongate element has a tensile modulus of less than 10 Mpa. The clamping device of any previous clause, wherein the second portion of the elongate element has a tensile modulus of at least 2000 Mpa. The clamping device of any previous clause, wherein the base element is a part of, or is connected to, a wearable article. A helmet, including a clamping device according to any preceding clause. A helmet according to clause 21 , wherein the second portion of the elongate element is connected to, or formed integrally with, a chin strap of the helmet. A protective pad, including a clamping device according to any one of clauses 1 to 20. A vehicle restraint system, including a clamping device according to any one of clauses 1 to 20. A vehicle restraint system according to clause 24, including a seat belt which is connected to, or formed integrally with, the second portion of the elongate element.

Claims

Claims1 . A clamping device for selectively clamping a portion of a strap in response to an increase in the strap tension, the locking device comprising: a base element having a first clamping surface; a spring element having a second clamping surface and mounted with respect to the base element so that the first and second clamping surfaces face, and are spaced apart from one another; an elongate element which is fixed in place at a first end thereof, and has a first portion near the first end which has a first tensile modulus, and a second portion, further from the first end than the first portion, which has a second tensile modulus, which is higher than the first tensile modulus, and wherein the second portion of the elongate element is positioned between the first and second clamping surfaces; and a guide component having a guide surface over which the elongate element passes, wherein, when the elongate element is pulled in a first direction, the elongate element exerts a force on the guide surface, which tends to deflect the first clamping surface towards the second clamping surface.

2. The clamping device of claim 1 or 2, wherein one or both of the clamping surfaces comprises a plurality of protrusions to engage the second portion of the elongate element.

3. The clamping device of any previous claim, wherein one or both of the clamping surfaces comprises a high friction coating or finish.

4. The clamping device of any previous claim, wherein the clamping surfaces have complementary or substantially complementary surface profiles.

5. The clamping device of any previous claim wherein one of the base element or spring element comprise a raised feature, protruding from a surface thereof that faces towards the other one of the base element and spring element, wherein the first or second clamping surface is between the raised feature and the free end of the one of the base element or spring element.

6. The clamping device of any previous claim, wherein the guide component comprises an enclosed loop, through which the elongate element passes.

7. The clamping device of any previous claim, wherein the spring element and the base element are joined together.

8. The clamping device of any previous claim, wherein the elongate element comprises a third portion, the third portion having a third tensile modulus.

9. The clamping device of any previous claim, wherein the guide component is a part of the spring element.

10. A helmet, including a clamping device according to any preceding claim.

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