WO2014023953A1

WO2014023953A1 - An air-release trigger

Info

Publication number: WO2014023953A1
Application number: PCT/GB2013/052101
Authority: WO
Inventors: Warren Stanley
Original assignee: AIRBAG TECHNOLOGIES Ltd
Current assignee: AIRBAG TECHNOLOGIES Ltd
Priority date: 2012-08-08
Filing date: 2013-08-07
Publication date: 2014-02-13
Anticipated expiration: 2015-02-08
Also published as: GB2504740A; GB201214190D0

Description

An Air-Release Trigger

FIELD OF THE INVENTION

The present invention relates to an air-release trigger and a body protector for use with such an air-release trigger.

BACKGROUND OF THE INVENTION

Falls that occur in a wide range of sporting activities and workplace environments can result in serious injuries and even fatality. To reduce the impact of a fall, it is known to provide an inflatable body protector, such as a jacket. The body protector comprises an inner air bag and an outer fabric layer. Attached to the body protector is an air-release trigger which is connected to a gas canister via a threaded connection. The air-release trigger is configured to inflate the airbag of the body protector as the user falls. In use, the user wears the body protector and attaches one end of a lanyard to the air- release trigger of the body protector and the other end to a part of a vehicle or animal, or the like, from which the user may fall. In the event that the user falls, the lanyard pulls on the air-release trigger which in response releases the gas from the gas canister so that the body protector inflates and absorbs some of the forces of the fall.

SUMMMARY OF THE INVENTION

The present invention seeks to provide an improved air-release trigger for use with a body protector. According to the present invention, there is provided an air-release trigger for an inflatable body protector, comprising a housing, a piston slidably received in the housing, a biasing member configured to urge the piston along a path in the housing, and a release element having an engaging surface locatable against a contact surface of the piston so as to act against the force of the biasing member, wherein a portion of the engaging surface extends away from the contact surface of the piston when the release element acts on the piston.

Preferably, the piston comprises a recess formed with the contact surface, and the release element is receivable in the recess. Conveniently, the release element comprises a body having an end surface and a peripheral surface, and the portion of the engaging surface extends between the end surface and the peripheral surface. In one embodiment, the portion of the engaging surface extends away from the contact surface at an angle of 8o° relative to the end surface.

Preferably, the portion of the engaging surface extends between 20% and 80% of a height of the contact surface of the recess.

The air release trigger may further comprise an air release valve configured to selectively release air from an inflated body protector so that the body protector deflates. According to another aspect of the invention, there is provided an air-release trigger for an inflatable body protector, comprising a housing mountable to an inflatable body protector, a trigger mechanism disposed in the housing configured to actuate a pressurised gas supply so that the inflatable body protector inflates, and an air release valve configured to selectively release air from the inflated body protector so that the body protector deflates.

Conveniently, the housing comprises an air flow passage for directing pressurised gas supply to an inflatable body protector and the air release valve is formed on the housing such that it connects to the air flow passage.

In one embodiment, the housing comprises a bore, and the triggering mechanism comprises a piston slidably received in the bore and a biasing member configured to urge the piston in a direction of the bore, and a release element configured to act on the piston against the force of the biasing member, wherein the air release valve is formed on the housing so that air is released via the bore through the air release valve.

Preferably, the air release valve comprises an air outlet and a slideable cover configured to selectively seal the air outlet. According to yet another aspect of the invention, there is provided an air-release trigger for an inflatable body protector, comprising a housing formed with a bore, a piston having a piercing element, the piston being slidably received in the bore, a biasing member configured to act on the piston to urge it towards an end of the housing, and a release element configured to act on the piston against the force of the biasing member, wherein the housing comprises an air outlet for directing air into an inflatable body protector, wherein the air outlet has a cross-sectional area that is at least 6.3 times greater than the cross-sectional area of the piercing element.

In one embodiment, the housing comprises a bayonet fitting for receiving a gas canister having a cooperating bayonet fitting.

In another embodiment, the air-release trigger further comprises an adapter converting a threaded connection of a gas canister to a bayonet fitting such that it can be connected to the bayonet fitting of the housing. The adapter may comprise a cylindrical wall having an internal threaded surface and an outer surface formed with a protrusion, a free end of the cylindrical wall is formed with a flange having a cut out portion.

According to yet a further aspect of the invention, there is provided an inflatable body protector comprising an air release trigger as described above.

The inflatable body protector may comprise an inner air bag and an outer layer, wherein the air release trigger is mounted to a base plate disposed in the inner air bag such that the outer layer and the inner air bag is layered between the air release trigger and the base plate.

According to another aspect of the invention, there is provided a kit for use with an air- release trigger of a body protector comprising a set of interchangeable release elements having an engaging surface configured to be locatable against a contact surface of a piston that forms part of a trigger mechanism of an air-release trigger, wherein a portion of the engaging surface of each release element is tapered such that in use, the portion extends away from the contact surface of the piston.

The release element may comprise a body having an end surface and a peripheral surface, and the portion of the engaging surface extends between the end surface and the peripheral surface. According to a further aspect of the invention, there is provided a kit for use with a body protector comprising the kit described above and an air-release trigger.

In one embodiment, the air release trigger comprises a housing, a piston slidably received in the housing, a biasing member configured to urge the piston along a path in the housing, and the release element having the engaging surface is locatable against the surface of the piston so as to act against the force of the biasing member.

Preferably, the piston comprises a recess formed with the contact surface , the release element is receivable in the recess.

In one embodiment, the portion of the engaging surface extends away from the contact surface at an angle of 8o° relative to the end surface. The portion of the engaging surface may extend between 20% and 80% of a height of the contact surface of the recess.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which;

Figure 1 shows an exploded view of an air-release trigger according to the present embodiment;

Figure 2 shows a perspective view from above of a housing of the air-release trigger; Figure 3 shows a perspective view from below of the housing of the air-release trigger; Figure 4 shows a perspective view of a thread to bayonet adapter;

Figure 5 shows a piston;

Figure 6 shows a cross-sectional view of a release element in a recess;

Figure 7 shows a cross-sectional view of a release element partially withdrawn from a recess;

Figure 8 shows a transparent view of an embodiment of a release element;

Figure 9 shows a transparent view of another embodiment of the release element; and

Figure 10 shows a transparent of a further embodiment of the release element. DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to figure l, an air-release trigger l for use with a gas canister comprising compressed gas is shown. The air-release trigger 1 is attachable to an inflatable body protector such as a jacket so that in use, the air-release trigger 1 in combination with the gas canister can inflate a body protector in response to the air-release trigger being actuated by, for example, the user falling off a vehicle or an animal.

The air-release trigger l comprises a housing 3 having a cylindrical bore 6 which is defined by a wall 5. The bore 6 extends along a longitudinal axis 'A' of the housing 3. The wall 5 is integrally formed with a rectangular shaped platform 7 wherein a longitudinal axis 'B' of the platform is parallel to the longitudinal axis 'A' of the bore 6 as seen in figure 1. The bore 6 comprises two opposing coaxial openings 6a, 6b. In an upper facing part of the wall 5, a hole 8 for receiving a release element 52 is formed. Adjacent to the hole 8, a dent 9 engaging a sliding cover 40 and a second air outlet 11 are formed as can be appreciated from Figure 2. On an opposing side of the wall 5 to the second air outlet 11, a first air outlet 13 is formed as can best be seen in Figure 2. The first air outlet 13 is defined by a tube 14 that extends from the bore 6 perpendicular to the longitudinal axis 'A' of the housing 3 as seen in Figure 3. The diameter of the second air outlet is 13.8mm. The free end of the tube 14 extends beyond the plane of a bottom surface 7a of the platform 7. Surrounding the tube 14, is an outer wall 12 that is integrally formed with the housing 3. A space is formed between the tube 14 and the outer wall 12 for receiving a step 38 of a base plate 30 as explained in more detail below. The platform 7 is further formed with four mounting holes 10 as seen in Figures 1 to 3. More specifically, two holes 10 are formed along each of the longitudinal edges of the platform 7.

The wall 5 defining the bore 6 has two opposing ends. A first end 14 is threaded so as to receive a corresponding threaded screw cap 15 as illustrated in Figure 1. An outer surface of the screw cap 15 is formed with ribs 16 so as to enable a user to screw the screw cap 15 by hand. The screw cap 15 is also formed with an integral nut 17 on a surface of the screw cap facing away from the bore 6. The integral nut 17 enables a user to either use a corresponding hex key (not shown) or a spanner (not shown) to screw the screw cap on or off the threaded first end 14. Marks 18a, 18b can be formed on the screw cap and the upper part of the wall 5 of the housing 3 which align when the screw cap has been fully screwed onto the threaded first end 14.

At the opposite end 19 to the threaded first end 14 of the wall 5 of the housing 3, a female bayonet fitting 4 is formed as best seen in Figure 2. The female bayonet fitting 19 comprises two opposing widened regions 21 which accommodate for corresponding male bayonet protrusions 22 of a male bayonet fitting 23 to be connected to the female bayonet fitting 4. The female bayonet fitting 4 further comprises two opposing slots 24 that are formed in the w^Tall 5 of the housing 3 immediately adjacent to the widened regions 21 and that extend in a rotational direction about the 'A' axis of the housing 3. When the male bayonet fitting 23 is connected to the female bayonet fitting 4, the protrusions 22 of the male bayonet fitting locate in a part of the respective slot that extend away from the widened regions 21 thereby preventing the male bayonet fitting from disconnecting from the female bayonet fitting in a direction parallel to the 'A' axis of the housing 3. An inner surface of the female bayonet fitting 4 is formed with a 2mm lip (not shown) which creates an air tight seal when a male bayonet fitting 23 is connected to the female bayonet fitting 4.

On an end surface of the female bayonet fitting 4, two small projections 25 are formed (see Figure 2) that engage with corresponding cut outs 26 formed in a flange 27 of the male bayonet fitting 23 as can best be seen in Figures 3 and 4. This is explained in more detail below.

The male bayonet fitting 23 may be formed directly on a gas canister or as a separate component wherein it functions as an adapter for gas canisters having a threaded connection. A separate male bayonet adapter 20 is shown in Figure 4 and it comprises a cylindrical wall 28 having an internal threaded surface 29 for receiving a corresponding threaded end of a gas canister. On one end of the cylindrical wall 28, the flange 27 is formed with two cut out portions 26 and on a peripheral outer surface of the cylindrical wall 28 towards the opposite end of the flange 27 the two protrusions 22 are formed.

The male bayonet adapter 20 is used by first screwing it onto a threaded connection end of a gas canister and thereafter the gas canister is ready to be used with the air- release trigger 1 described above. To connect the male bayonet fitting 23 with the female bayonet fitting 4, the protrusions 22 of the male bayonet fitting 23 are aligned with the widened regions 21 of the female bayonet fitting 4. The male bayonet fitting 23 is thereafter pushed into the female bayonet fitting 4 such that the protrusions 22 are located in the slots 24. Finally the male bayonet fitting 23 is rotated clockwise until the protrusions 22 locate in a part of the slots 24 that extend away from the widened regions 21 and the small projections 25 locate in the cut outs 26 of the flange 27 of the male bayonet fitting 23. The small projections 25 locating in the cut outs 26 prevent the male bayonet fitting 23 from inadvertently rotating and disconnecting from the female bayonet fitting 4.

The bayonet fitting of the air-release trigger 1 provides the advantage that a gas canister is easy to connect and disconnect as the gas canister only has to be turned

approximately a quarter of a turn for it to be connected or disconnected from the air- release trigger. Furthermore, there is a smaller margin for a user to incorrectly connect the gas canister to the air-release trigger in comparison to a threaded connection as is known from the prior art, because there is only a quarter of a turn that is required for the connection to be secure and the engagement of the projections 25 and the cut outs 26 in the flanges 27 gives a visual and audible reassurance to the user that the gas canister has been properly secured to the air-release trigger 1.

The air-release trigger 1 further comprises a cover 40 that locates on an outer surface of the wall 5 of the housing 3. The cover 40 is slideable between first and second positions so as to form an air-release valve together with the second air out let 11. More specifically, in the first position the cover 40 covers the air outlet 11. This setting is used when the air-release trigger 1 has been loaded and not yet actuated. After the air-release trigger 1 has been actuated and the body protector has been inflated, a user can slide the cover 40 in a direction parallel to the 'A' axis of the housing 3 towards the first threaded end 14 so as to expose the air outlet 11. This enables a user to easily and quickly deflate the body protector so that it can be reused. A lower surface (not shown) of the cover 40 comprises a raised bead (not shown) which locates in the dent 9 of the upper part of the housing 3 when the cover 40 is in its first position so as to ensure the user that the air outlet 11 has been properly closed.

As the second air-outlet 11 connects to the bore 6, air is released from the body protector by sliding the cover 40 to its second position such that air is expelled from the body protector through the first air-outlet 13 into the bore 6, and then out through the second air-outlet 11. It should be appreciated that the second air-outlet may be formed along any passage of the housing that directs the pressurised air to the inflatable body and so is not limited to being formed on the housing and connecting to the bore 6. It is also envisaged that an air release valve may be formed on the platform 7 of the housing 3.

It should be understood that the cover is not limited to being slidable. It may alternatively be removably attachable. Furthermore, it should be appreciated that the cover 40 and the second air outlet 11 are optional. For example, in an alternative embodiment, the housing is not formed with a second air outlet or a cover. Instead, the gas is expelled by removing the gas canister 2 so that the air can escape via the female bayonet fitting 4. The air-release trigger 1 is configured to be mounted onto a base plate 3. The base plate is shown in Figure 1 and it comprises a first 31 and a second surface 32. The first surface 31 is formed with a rectangular shaped lip 33 that corresponds to the platform 7 of the housing 3 such that when the air-release trigger 1 locates onto the first surface 31 of the base plate 30 the lip 33 is received inside the platform 7 so as to create a seal and to prevent the air-release trigger 1 from sliding relative to the base plate 30. The base plate 30 is further formed with four holes 34 that correspond to the mounting holes 10 in the platform 7 of the air-release trigger 1. Bolts 36 are configured to be received in each of the paired holes 10, 34 so as to secure the air-release trigger 1 to the base plate 30. A large aperture 37 defined by a step 38 is formed inside the rectangular lip 33 as seen in Figure 1. The large aperture 37 receives the tube 14 of the air outlet 13 of the air- release trigger 1 when the air-release trigger 1 is mounted to the base plate 30. The outer wall 12 of the air-release trigger 1 locates on the outside of the step 38 such that the step is sandwiched between the tube 14 and the outer wall 12. This arrangement creates an air tight seal between the air-release trigger 1 and the base plate 30.

In use, the air-release trigger 1 is attached to an inflatable body protector such as a jacket. The body protector (not shown) comprises an inner air bag and an outer layer. The inner air bag is air tight and inflates when the air-release trigger has been actuated. The outer layer is a protective layer which is typically formed out of a fabric. To attach the air-release trigger 1 according to the present invention to a body protector the base plate 30 is located within the air bag and there after the air bag is sealed. An air inlet and four bolt receiving holes are formed in the bag that correspond to the large aperture 38 and the four holes 34 in the base plate 30. Thereafter, the outer layer of the body protector is laid on top of the air bag and base plate, and corresponding holes is formed in said outer layer. Finally, the air-release trigger 1 is mounted to the base plate 30 such that the air bag and the outer layer are sandwiched between said base plate 30 and air-release trigger 1. The air-release trigger 1 is mounted to the base plate 30 by positioning the platform 7 of the housing 3 around the rectangular lip 33 formed on the base plate 30. The air inlet formed in the air bag is sandwiched between the tube 14 of the air outlet 13 of the housing 3 and the step 38 of the base plate 30 such that an air tight seal is formed between the air-release trigger 1 and the air bag.

The trigger mechanism of the air-release trigger 1 will now be described with reference to Figures 1 and 5. The trigger mechanism comprises a piston 50, a biasing member such as a 50kg compression spring (not shown) and a release element52. The piston 50 is located in the bore 6 of the housing 3 and is movable along the longitudinal axis Ά'. The piston 50 is in the shape of a cylinder and on its peripheral surface a release element receiving recess 53 is formed as seen in Figure 5. On the end surface of the piston facing towards the bayonet fitting end 4 of the housing 3 a piercing element 54 is provided and on the opposite end surface of the piston 50 a retaining pin 55 is formed. The biasing member (not shown) is located around the retaining pin 55 and within the screw cap 15. On the peripheral surface of the piston 50 adjacent to the end surface formed with a piston point 54, a piston seal 56 is formed. Preferably, the piston seal 56 is made out of polytetrafluoroethylene (PTFE). The piston seal 56 creates an air tight seal between the wall 5 of the housing 3 and the piston 50.

The release element 52 locates in the release element receiving recess 53 formed on the piston 50 via the hole 8 formed on the wall 5 of the housing 3. The release element 52 comprises a cylindrical body 60 having a central axis 'C and the body is 11.25mm long in a direction of the central axis 'C as illustrated in Figures 8 to 10'. A passage 61 is formed along the central axis 'C of the cylindrical body 60. The passage 61 has a circular cross-section with varying diameter. From an end surface 66 the diameter of the passage 61 is larger and is referred to as D2, the diameter is thereafter reduced to a smaller diameter Di, until the passage turns into a funnelled end 62. A lanyard (not shown) is received in the passage 61. An end portion of the lanyard is provided with a cylindrical element having the same diameter as the larger diameter D2 of the passage 61. The lanyard is received in the passage such that the cylindrical element locates in the part of the passage having the larger diameter D2 with the lanyard extending through the funnelled end 62. This arrangement enables the release element 52 to move along the lanyard in a first direction along the central axis 'C and away from the cylindrical element, but prevents the release element 52 from moving along the lanyard in the opposite direction.

The cylindrical body 60 is further formed with an outer engaging surface that extends between the funnelled end 62 and an opposing end surface 66 of the body as can be appreciated in Figures 6 to 10. More specifically, the engaging surface includes at least a portion of the peripheral surface 67 and a tapered surface 63, 64, 65, and the engaging surface is defined as the surface of the release element 52 that engages a contact surface 70 of the recess 53 of the piston when the release element is located therein. Furthermore, the tapered surface 63, 64, 65 is a portion of the engaging surface that is tapered or angled in such a way that it extends away from the contact surface 70 of the piston when the release element acts on the piston. The contact surface 70 of the piston is shown in Figures 5 to 7 and it is the surface of the recess that engages with the engaging surface of the release element 52. Figure 6 shows a cross-sectional view of the release element 52 located in the recess 53 and Figure 7 shows a cross-sectional view of the release element 52 as it is partially withdrawn from the recess 53. The arrows in these two figures represent the urging force of the biasing member acting on the piston 50. The release element 52 also acts on the piston 50 but against the force of the biasing member. This is achieved by the release element 52 being held in its position by the hole 11 formed in the housing 3. Thus, the release element 52 prevents the piston 50 from being urged along the bore 6 of the housing 3. As the force of the piston 50 acts perpendicular to the central axis C of the release element 52, the engaging surface includes at least a portion of the peripheral surface 67 of the body when the release member is located in the recess 53. This engaging surface engages the contact surface 70 of the recess 53.

As the release element 52 is withdrawn from the recess 53 the peripheral surface 67 continues to engage the contact surface 70 of the recess 53. When the release element 52 has been partially withdrawn as illustrated in Figure 7, the tapered surface 63, 64, 65 is in contact with a small upper part 71 of the contact surface 70 of the recess 53 such that it is the tapered surface 63, 64, 65 that is the engaging surface of the release element 52. Due to the fact that the engaging surface is at this stage tapered and contacts only a small part of the contacting surface 70 of the recess 53 there is less frictional force between the two components and so less force is required to pull out the release element 52 from the recess 53.

Figures 8, 9 and 10 show different embodiments of the release element 52 wherein the tapered surface 63, 64, 65 is of the same angle but differs in the length that they extend relative to the central axis 'C. In the embodiment illustrated in Figure 9, the

dimensions of the tapered surface are .32 x 8o° such that it is of an angle of 8o° relative to the end surface 66 of the body (shown as 'G' in the drawings) and it extends for 2.20mm (shown as 'J' in Figure 9) from the end surface 66 relative to the central axis 'C\ In the embodiment illustrated in Figure 8, the tapered surface has the same angle of 8o° ('G') relative to the end surface 66 and it extends for 1.20mm (T) relative to the central axis 'C and in the embodiment shown in Figure 10, the tapered surface has an angle of 8o° ('G') and extends for 2.80mm ('Κ') relative to the central axis 'C Although not shown in any of the drawings, it shall be understood that the release element receiving recess 53 may be formed with a corresponding shape so that the release element 52 fits snugly in the release element receiving recess 53, however this is optional.

By altering the length that the tapered surface 63, 64, 65 extends relative to the height Ή' of the contact surface 70 of the recess, the force required to pull the release element 52 out of the recess 53 can be changed. In the embodiments shown in Figures 8 to 10, the height Ή' of the contact surface 70 of the recess 53 is 3.9mm. Therefore, the tapered surface extending for 1.20mm relative to its central axis of the embodiment shown in Figure 8 corresponds to 30.8% of the height of the contact surface. The tapered surface extending for 2.20mm as shown in Figure 9 corresponds to 56.4% of the height of the contact surface and the tapered surface extending for 2.80mm as shown in Figure 19 corresponds to 71.8% of the height of the contact surface.

Due to the varying lengths of which the tapered surface extends relative to the height of the contact surface, the release element shown in Figure 8 having a tapered surface extending for 30.8% of the height of the contact surface, requires a weight of 29±ikg so as to be disconnected from the piston 50, whereas the embodiment shown in Figures 9 and 10 require a weight of 25±ikg and 2i±ikg, respectively. Therefore, by altering the length of which the tapered surface extends relative to the height of the contact surface, the air-release trigger can be adapted to the weight of the rider. Thus, a child typically weighing less than an adult requires a more sensitive triggering mechanism and so the release element is formed with a tapered surface that extends for a greater length relative to the height of the contact surface than those adapted for adults.

The configuration of the release element 52 enables, for example, two users having different weights to share the same inflatable body protector as they can easily change the release element suitable for their weight when they are to where the body protector. Thus, it is envisaged that the present invention includes an embodiment comprising a kit of release elements having different tapered surfaces such that a body protector can be used by people having different weights. It should be understood that the tapered surface is not limited to the dimensions described above, but can be of any dimension that is suitable for the weight of a user. Thus, the tapered surface relative to the central axis can extend between 20% and 80% of the length of the contact surface 71 of the recess 53. For example, the tapered surface may extend relative to the central axis for 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80% of the length of the contact surface. It shall also be understood that the tapered surface is not limited to having an angle of 8o° relative to the end surface 66 but can be adjusted to any other suitable angle so as to adapt the release element to the weight of the user. It is envisaged that the air release element is not limited to being cylindrical.

Alternatively, it may be cubical or oval formed with a tapered surface.

Loading of the air-release trigger 1 will now be described. The screw cap 15 is unscrewed from the threaded first end 14 of the housing 3 either by hand or by using a tool such as a hex key or a spanner. The screw cap 15 is unscrewed until the recess 53 in the piston 50 is visible through the hole 8 formed in the upper part of the wall 5 of the housing 3. The recess 53 is aligned with the hole 8 and the release element 52 is located in the recess 53. The screw cap 15 is thereafter tightened until the marking 18b on the screw cap aligns with the corresponding marking 18a on the housing 3. This fully compresses the compression spring and as a result potential energy is stored in the compression spring. A full unused gas canister 2 having a male bayonet fitting 23 (or in the case of a threaded male fitting; a bayonet male adapter 20 is attached to the threaded male fitting) is attached to the female bayonet fitting 4 of the air-release trigger 1 by the protrusions 22 of the male bayonet fitting 22 being aligned with the widened areas 21 of the female bayonet fitting 4 of the housing 3 and thereafter the male bayonet fitting 23 is pushed into the female bayonet fitting 4 so that the protrusions 22 locate in their respective slots 24. The gas canister is thereafter rotated clockwise until the protrusions 22 locate in a part of the slots 24 that extend away from the widened regions 21 and so that the projections 25 of the housing 3 locate in the cut outs 26 of the flange 27 of the male bayonet fitting 23. The gas canister 2 is now held in place and can only be disconnected from the air-release trigger 1 by rotating the gas canister 2 in an anti-clockwise direction for approximately a quarter of a turn so that the protrusions 22 align with the widened regions 21 of the female bayonet fitting 4.

Operation of the air-release trigger 1 will now be described. The air-release trigger 1 is attached to a body protector (not shown) and loaded as described above. It is envisaged that the release element 52 is attached to an end of a lanyard (not shown) and that the opposite end is connected to a vehicle or animal (not shown) that the user is riding. As the user falls off, the lanyard pulls the release element 52 out of the recess 53 such that there is nothing urging the piston 50 against the force of the compression spring. Thus, the compression spring releases its stored energy and pushes the piston 50 along the bore 6 towards the gas canister 2. The piercing element 54 pierces a seal of the gas canister 2 so that the compressed gas in the gas canister is released. The compressed gas forces the piston 50 back in a direction towards the screw cap 15. The compressed gas cannot escape pass the piston 50 in the bore 6 due to the PTFE piston seal 56 creating an air tight seal between the wall 5 of the housing 3 and the piston 50. As the piston 50 is pushed back a free air flow passage is formed between the gas canister 2 and the first air outlet 13 of the housing 3 such that the air flows from the gas canister 2 into the housing 3 through the first air outlet 13 into the air bag of the body protector. The air bag of the body protector is fully inflated within milliseconds and so protects the user from the impact of the fall.

The piercing element 54 has a diameter of 5.5mm and so creates a corresponding opening in the seal of the gas canister. This diameter is the smallest diameter along the air flow passage as the bore has a diameter of 16.20mm and the second air outlet 13 has a diameter of 13.8mm. Thus, the cross-sectional areas of the piercing element and the air outlet are 23.8mm² and 149.6mm², respectively, and so the ratio therebetween is 1:6.3. The advantage of having such a larger air outlet 13 relative to the piercing element 54 is that the air can quickly flow along the air passage into the body protector such that the body protector is quickly inflated.

After the body protector has been used and it is inflated it can be deflated by sliding the cover 40 in a direction towards the threaded first end 14 so that the second air outlet 11 is exposed. The air in the air bag can then easily be expelled from the air bag via the first air outlet 13 into the housing 3 and then through the second air outlet 11.

It is envisaged that the gas canister used with the air-release device contains compressed carbon dioxide, however it should be understood that any alternative gas can be used that is suitable for use with any gas canister that can be safely compressed and used with a body protector. Furthermore, it should be understood that the term "air" used herein includes any gas suitable for inflating a body protector.

Although not illustrated, the piston and the bore are not limited to having a circular cross-section. They can be of any cross-section such as square or oval. Furthermore, in another un-illustrated embodiment, the bayonet fitting is reverse such that the female bayonet fitting is formed on the gas canister and the male bayonet fitting is formed on the air-release trigger.

The air-release trigger according to the present invention can be used with a body protector for any sporting activity or workplace environment, for example, motorcycle or horse riding, wherein the impact of a user's fall can be reduced by an inflatable body protector.

Although embodiments of the invention have been shown and described, it will be appreciated by those skilled in the art that variations may be made to the above exemplary embodiments that lie within the scope of the invention, as defined in the following claims

Claims

1. An air-release trigger (1) for an inflatable body protector, comprising a housing (3)_> a piston (50) slidably received in the housing (3), a biasing member configured to urge the piston (50) along a path in the housing (3), and a release element (52) having an engaging surface locatable against a contact surface (70) of the piston (50) so as to act against the force of the biasing member, wherein a portion (63, 64, 65) of the engaging surface extends away from the contact surface of the piston when the release element (52) acts on the piston (50).

2. An air-release trigger according to claim l, wherein the piston (50) comprises a recess (53) formed with the contact surface, and the release element (52) is receivable in the recess (53).

3. An air-release trigger according to claim 2, wherein the release element (52) comprises a body having an end surface (66) and a peripheral surface (67), and the portion (63, 64, 65) of the engaging surface extends between the end surface (66) and the peripheral surface (67).

4. An air-release trigger according to claim 3, wherein the portion (63, 64, 65) of the engaging surface extends away from the contact surface (70) at an angle of 8o° relative to the end surface (66).

5. An air-release trigger according to claim 3 or 4, wherein the portion (63, 64, 65) of the engaging surface extends between 20% and 80% of a height of the contact surface (70) of the recess.

6. An air release trigger according to any of claims 1 to 5, further comprising an air release valve (11, 40) configured to selectively release air from an inflated body protector so that the body protector deflates.

7. An air-release trigger (1) for an inflatable body protector, comprising a housing (3) mountable to an inflatable body protector, a trigger mechanism disposed in the housing (3) configured to actuate a pressurised gas supply so that the inflatable body protector inflates, and an air release valve (11, 40) configured to selectively release air from the inflated body protector so that the body protector deflates.

8. An air-release trigger according to claim 7, wherein the housing (3) comprises an air flow passage for directing pressurised gas supply to an inflatable body protector and the air release valve (11, 40) is formed on the housing (3) such that it connects to the air flow passage.

9. An air release trigger according to claim 7 or 8, wherein the housing (3) comprises a bore (6), and the triggering mechanism comprises a piston (50) slidably received in the bore (6) and a biasing member configured to urge the piston in a direction of the bore, and a release element (52) configured to act on the piston (50) against the force of the biasing member, wherein the air release valve (11, 40) is formed on the housing (3) so that air is released via the bore (6) through the air release valve.

10. An air-release trigger according to any preceding claim, wherein the air release valve comprises an air outlet (11) and a slideable cover (40) configured to selectively seal the air outlet (11).

11. An air-release trigger (1) for an inflatable body protector, comprising a housing (3) formed with a bore (6), a piston (50) having a piercing element (54), the piston being slidably received in the bore (6), a biasing member configured to act on the piston (50) to urge it towards an end (19) of the housing (3), and a release element configured to act on the piston (50) against the force of the biasing member, wherein the housing comprises an air outlet (13) for directing air into an inflatable body protector, wherein the air outlet (13) has a cross-sectional area that is at least 6.3 times greater than the cross-sectional area of the piercing element (54).

12. An air-release trigger according to any of the preceding claims, wherein the housing (3) comprises a bayonet fitting (4) for receiving a gas canister having a cooperating bayonet fitting.

13. An air release trigger according to claim 12, further comprising an adapter (20) converting a threaded connection of a gas canister to a bayonet fitting such that it can be connected to the bayonet fitting (4) of the housing (3).

14. An air release trigger according to claim 13, wherein the adapter (20) comprises a cylindrical wall (28) having an internal threaded surface (29) and an outer surface formed with a protrusion (22), a free end of the cylindrical wall is formed with a flange (27) having a cut out portion (26).

15. An inflatable body protector comprising an air release trigger as claimed in any of claims 1 to 13.

16. An inflatable body protector according to claim 15, comprising an inner air bag and an outer layer, wherein the air release trigger (1) is mounted to a base plate (30) disposed in the inner air bag such that the outer layer and the inner air bag is layered between the air release trigger (1) and the base plate (30).

17. A kit for use with an air-release trigger of a body protector comprising a set of interchangeable release elements (52) having an engaging surface configured to be locatable against a contact surface of a piston that forms part of a trigger mechanism of an air-release trigger, wherein a portion (63, 64, 65) of the engaging surface of each release element is tapered such that in use, the portion extends away from the contact surface of the piston.

18. A kit according to claim 17, wherein release element (52) comprises a body having an end surface (66) and a peripheral surface (67), and the portion of the engaging surface extends between the end surface (66) and the peripheral surface (67).

19. A kit for use with a body protector comprising the kit claimed in claim 17 or 18 and an air-release trigger.

20. A kit according to claim 19, wherein the air release trigger (1) comprises a housing (3), a piston (50) slidably received in the housing (3), a biasing member configured to urge the piston (50) along a path in the housing (3), and the release element (52) having the engaging surface is locatable against the surface of the piston so as to act against the force of the biasing member.

21. A kit according to claim 20, wherein the piston (50) comprises a recess (53) formed with the contact surface (70), the release element (52) is receivable in the recess (53)-

22. A kit according to claim 21, wherein the portion (63, 64, 65) of the engaging surface extends away from the contact surface (70) at an angle of 8o° relative to the end surface (66).

23. A kit according to claim 21 or 22, wherein the portion (63, 64, 65) of the engaging surface extends between 20% and 80% of a height of the contact surface (70) of the recess.