Valves

Abstract

A valve for a bicycle tyre inflator has first and second main body parts, which slide relative to one another, and which are preferably biased, by a spring, towards a closed position. The first main b

Description

This invention relates to valves, and in particular, but without limitation, to valves suitable for inflating bicycle tyres. Most modern bicycle tyres are pneumatic and comprise a tyre, which is sealingly fitted to the rim of a wheel. A one-way / check valve passes through a wall of the wheel and permits the interior of the tyre to be inflated by compressed gas. Modern bicycles have tubeless tyres, that is to say, without an inner tube as this has various advantages in terms of reducing weight and inertia, as well as the ability to absorb greater amounts of shock loading. However, if the rim of the tyre unseats from the rim of the wheel, this can break the seal causing the inflation gas within the tyre to escape, causing a flat tyre. This situation can be remedied by using a pump or compressed air supply to re-inflate the tyre via the filling valve. In a "pit" situation, re-inflation of the tyre using a compressed gas source is relatively straightforward. However, mid-race, this is much more difficult. A conventional bicycle pump could, of course, be used to re-inflate the tyre, but it is disadvantageous to fit the bicycle with a pump due to various reasons including adding weight. The most common solution, and in particular for endurance racing bicycles, is for the rider to have on their person a compressed gas cylinder, which contains sufficient air to re-inflate a single tyre. This can be a relatively compact cylinder, namely around 10cm in length and is light weight. The cannister is essentially a single-used device, which can be offered up to the filling valve of the bicycle wheel fora one-time, rapid inflation of the tyre. Indeed, the gas from the cannister is dispensed in a matter of seconds, thereby almost instantly re-inflating the tyre and allowing the rider to continue the race with minimal disruption. Various types of nozzle / valve are known for this particular application and most of them have a screw-on hub, which connects to the gas cannister. The cannister can be partially screwed onto the device to hold it in position temporarily, or fully screwed in and by doing so, a needle spigot within the device punctures a hole into the cannister allowing the compressed gas therein to escape via the spigot and ultimately into the tyre. A check valve is nevertheless needed to prevent the gas from escaping from the cannister once the cannister has been punctured, but before the other end of the device has been sealingly offered up to the filling valve of the tyre. Such valves are generally spring-loaded devices, which are maintained in a closed position thereby containing the gas within the cannister, but which can be displaced by pushing the tip of the device onto the valve stem of the tyre so as to open the valve and cause the gas from the cannister to flow from the cannister into the tyre upon the application of axial stress. The majority of valves of this general type have a ball closure mechanism in them by which a ball bearing is used to form an airtight seal against an opening in the valve body. The pressurised gas within the cannister holds the ball bearing in position, but when the ball bearing is displaced from its valve seat, it enables gas to escape around it and out through the outlet of the device. Other types of valve of this general type are similar in operation, albeit having a flat disc or plate, which seats against an O-ring so as to form a seal. When the disc is compressed against the 0-ring, it forms a gas-type seal which prevents the egress of the compression gas. However, unseating the plate from the O-ring forms a gap enabling the inflation gas to escape from the cannister into the tyre. Such devices are well known and are available in in-line and right-angled versions - in-line versions being preferred because they reduce the likelihood of off-axis forces being applied to the valve stem and / or the neck of the cannister in use. This invention aims to provide an improved and / or alternative valving system for a rapid tyre inflator, as set out in the appended independent or dependent claims. The invention is set forth in the appended independent claim. Preferred and / or optional features are set forth in the appended dependent claims. It will be appreciated that the invention provides an alternative type of valve, which is suitable, in particular, for inflating bicycle tyres, which does not have the ball valve arrangement of known inflator valves. This addresses the problem of the ball occasionally becoming stuck or jammed, due to the ingress of dirt, debris or moisture into the device during normal use. By providing a system whereby there is a fluid pathway that is selectively opened or closed by relative movement of the first and the second main body parts, this provides a reliable on / off valve mechanism whilst obviating the need for any lose parts within the device. Suitably, O-ring seals are used throughout the valve, and in particular, for forming a seal between the first opening and the valve stem, and between the second opening and source of inflation gas, which is typically a gas cannister. The source of inflation gas is preferably a gas cannister which usually comes as a sealed container with a screw-threaded neck. In orderto accommodate this type of arrangement, the second opening suitably comprises a screw thread, and in particular, an internal screw thread, which engages the external screw thread at the neck of the gas cannister. Thus, the gas cannister can be offered up to the second main body part and screwed into position, thereby forming a sealed, detachable connection between the two. Preferably, the stem or the second main body part comprises a spike, which pierces the gas cannister as it is screwed into position. This enables the gas cannister to be engaged with the second main body part but not fully screwed home thus preserving the seal, or it enables the gas cannister to be fully screwed in and pierced by the spike, but with the fluid passageway between the gas cannister and the valve stem being blocked by the valve being in the first position. This particular arrangement facilitates quick and straightforward replacement of gas cannisters, which can be an advantage. Preferably, the first and second main body parts are biased towards the first position, that is to say the position in which the fluid passageway between the first and second openings is blocked by the O-rings. The advantage of biasing is that even if the cannister is screwed fully in and pierced, inflation gas will not escape unless and until the first and second main body parts have been moved to the second position. In practice, this means that the gas cannister can be screwed onto the device and pierced and then the valve offered up to a valve stem. It is only when the valve stem is axially pushed into the first opening and pushed fully home so as to move the first and second main body parts to the second position, that the inflation gas is allowed to flow into the tyre. For simplicity, the biasing means comprises a spring, such as a coil spring. In order to prevent the first and second main body parts from falling apart, the stem suitably comprises an end stop, which limits the extent of relative movement for the first and second main body parts. The maximum extent of movement is suitably the first and second positions, and this gives rise to a more reliable system in which there are only two possible modes of operation. The first and second openings are co-axial, or substantially co-axial. This means that the axis of the inflation cannister, the valve itself and the valve stem of the tyre to be inflated are all aligned, which avoids placing sheer forces or twisting moments onto the valve stem during operation of the valve. Ideally, the valve is of a construction that permits relatively easy assembly and / or disassembly for cleaning, maintenance and repair, etc. This is suitably accomplished, as shown in the following description and drawings, by providing screw-threaded connections between the various components and O-ring seals therebetween. This configuration usefully enables the valve to be taken apart and cleaned internally and / or for the O-ring seals to be replaced as they become word or abraded in use. An embodiment in the invention shall now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side view of an embodiment of a valve in accordance with the invention; Figure 2 is a cross-section of Figure 1 on A-A; Figure 3 is a partial, perspective view of the valve of Figures 1 and 2 in a closed position; and Figure 4 is a partial, perspective view of the valve of Figures 1 and 2 in an open position. An embodiment of a valve 10 in accordance with the invention has a main body 12, which is formed from a first part 14 and a second part 16, which are screw-threadingly 18 connected to one another, with an O-ring seal 20 therebetween. The first part 14 has an axial opening 22, into which a valve stem (not shown) can be inserted. A relatively large O-ring is provided around the axial opening 22 to form a radial seal between the first part 14 and the valve stem (not shown) when inserted into the axial opening 22. The axial opening has a blind end stop 26, again which the valve stem (not shown) engages when pushed into the axial opening 22. A coil spring 28 engages an internal shoulder 30 of the first part 14 and its opposite end engages the end face 32 of a stem 34. The stem 34 is axially moveable relative to the second part 16 and a pair of spaced apart O-rings 36, 38 are provided to form a radial seal between an outer surface of the stem 34 and the second part 16 of the main body 10. As can be seen in Figure 2 of the drawings, there is a small gap 40 between an end face 42 of the stem and an end face 44 of the second part 16 of the main body 10. This space 40 accommodates relative sliding of the stem 34 and main body 16. There is also a similar space 46 between a rear surface 48 of an end face 32 of the stem 34 and an internal end face 50 of the second part. It will be appreciated that these two spaces 40, 46 determine the extent of sliding movement of the stem 34 relative to the main body 10, with the respective end faces 42 / 44, 48 / 50 providing end stops to limit that movement. The stem 34 has a blind hole 54 in it, which has an egress hole 56 towards its end. The egress hole 56 provides a fluid communication pathway between the internal bore 54 and the outer surface of the stem 34, and hence the interior of the second part 16 of the main body 10. Extending axially within the stem 34 is a spike 58 which pierces a gas canister (not shown) when screwed onto the internal screw thread 60 of the stem 34. First 62 and second 64 O-rings are provided for forming a radial and end face seal, respectively, between the gas canister (not shown) and the stem 34 when screwed into position. It will be appreciated that the gas canister can be screwed into the screw thread 60 and a radial seal is formed by the first O-ring 62. Further screwing in of the gas cartridge causes the end of the cartridge to engage the second O-ring 64 thereby forming an end face seal. Further screwing causes the spike 58 to pierce the end of the gas canister enabling gas to flow through the bore 54 and towards the egress aperture 56. The end of the stem 34 preferably has wing formation 66, which facilitate screwing the gas canister onto the stem 34. When the gas canister has been screwed on and pierced by the spike 58, pressurised gas flows from the canister into the conduit 54. Gas escapes through the egress aperture 56 and fills an annular space between the O-rings 36, 38. This configuration is shown in Figure 3 of the drawings for clarity. Due to the gas pressure, the stem 34 is pushed away from the main body 10 and this causes the egress aperture 56 to lie at an axial position located between the upper O-ring 36 and the lower O-ring 38. The O-rings 36, 38 prevent egress of gas from the canister into the main body 16. The spring 28 also urges the main body 10 away from the stem 34, ensuring that the "at rest" position of the valve 10 is in the "closed" position, namely with the egress aperture 56 being located between the seals 36, 38. However, when a valve stem (not shown) is inserted into the end opening 22 of the upper part 14 of the main body 10, a radial seal around the valve stem is formed by the O-ring 24, and further insertion of the valve stem into the opening 22 causes the valve stem to engage with the end face 26. Further axial movement of the valve stem relative to the main body 10 causes the spring 28 to compress, allowing the stem 34 to move towards the main body 10 into a position as shown in Figure 4 of the drawings. Referring to Figure 4, it can be seen that the egress aperture 56 is now located above the upper O-ring 36, and this permits the passage of compressed gas from the gas canister (not shown) via the conduit 54, out through the egress aperture 56 and into the interior of the second part 16 of the main body 10. Gas is thus able to get into the valve stem (not shown) which is pushed into the end opening 22 thereby inflating a tyre (or other inflatable volume) connected to the valve stem. Once the gas pressure in the canister (not shown) has equalised with that in the tyre (not shown), the flow of gas will cease, at which point, the main body 10 can be pulled off the valve stem (not shown), which causes the spring 28 to expand and move the valve back into the "closed" position as shown in Figure 3 of the drawings. If there is any compressed air remaining in the gas canister, it can be reused in a further inflation operation. If the gas canister is empty, then it can be replaced by a fresh gas canister for the next inflation operation. The invention is not restricted to the details of the foregoing embodiment, which is merely exemplary of one embodiment of the invention.

Claims

1. A valve comprising:a first main body part with a first opening into which, in use, a valve stem of a tyre to be inflated can be sealingly inserted, the opening having a blind end stop, against which the valve stem engages when pushed axially into the opening;a second main body part with a second opening to which, in use, a source of inflation gas can be sealingly affixed, and a stem with an internal bore and an egress aperture located at a distance from a distal end of the stem; andfirst and second sealing members forming respective axially spaced-apart seals between a surface of the first main body part and an outer surface of the stem;the first and second main body parts being relatively moveable between a first position in which the egress aperture of the stem is located between the first and second sealing members, and a second position in which the egress aperture of the stem is located distally beyond both the first and second sealing members; whereinthe first and second openings are substantially coaxial; and whereinwhen the first and second main body parts are in the first position, a fluid pathway between the first and second openings is blocked by the first and second sealing members, butwhen the first and second main body parts are in the second position, a fluid pathway between the first and second openings is open thus permitting inflation gas to flow between the source of inflation gas and the valve stem.

2. The valve of claim 1, comprising an O-ring seal at the first opening to form the seal, in use, between the first main body part and the valve stem.

3. The valve of claim 1 or claim 2, comprising an O-ring seal at the second opening to form the seal, in use, between the second main body part and the source of inflation gas.

4. The valve of claim 1, 2 or 3, comprising a screw thread at the second opening, which is complementary with the screw thread of a gas canister, thus permitting a gas canister to be screw-threadingly, detachably, and sealingly affixed to the second main body part.

5. The valve of claim 4, wherein the stem comprises a spike projection, which pierces the gas canister as the gas canister is screw-threadingly affixed to the second main body part.

6. The valve of any preceding claim, further comprising biasing means adapted, in use, to bias the first and second main body parts towards the first position.

7. The valve of claim 6, wherein the biasing means comprises a coil spring.

8. The valve of any preceding claim, wherein the stem comprises an end stop, which limits the extent of relative movement of the first and second main body parts.

9. The valve of any preceding claim, wherein the first main body part comprises first and second components, which are screw threadingly connected to one another.

10. The valve of any preceding claim, wherein the second main body part and the stem are screw threadingly connected to one another.

11. The valve of claim 10 or claim 10, which can be disassembled and reassembled for maintenance, servicing and / or repair by sequentially unscrewing / screwing the respective parts with O-ring seals therebetween.

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