Improvements in or relating to actuation systems

Abstract

An apparatus and method for operating with and controlling high-pressure fluid is disclosed. The apparatus includes a dump chamber that receives high-pressure fluid from a high-pressure fluid source, and a dose chamber that receives a flow of high-pressure fluid from the dump chamber via a flow path from the dump chamber to the dose chamber and has an outlet. There is also a work chamber with an inlet end at its end, and a dose valve member with an annular sealing surface surrounding the inlet end. When the dose valve member is in a closed state, the sealing surface abuts an annular seat to seal the outlet, and when the dose valve member is in an open state, a gap is presented between the annular sealing surface and the seat to allow high-pressure fluid to move from the outlet to the inlet. The high-pressure fluid in the dump chamber holds the dose valve member in a closed state, at least in part, until the pressure of the high-pressure fluid in the dump chamber is reduced, thereby allowing the high-pressure fluid in the dose chamber to release the dose valve member to an open state.

Description

[Technical field]

[0001] The present invention relates to an actuation system for a high pressure fluid powered device.

[0002] In particular, but not by way of limitation, the present invention is directed to valves and methods of actuating the valves to release or impart energy. [Background technology]

[0003] There is a need to control and release energy, particularly energy transmitted, delivered or released by high pressure fluids.

[0004] In one example, a high pressure fluid, such as a compressed gas, e.g., air or carbon dioxide, can be used to perform work. In one such example, for example and without limitation, in a tool such as a nail gun, compressed air can be regulated by a valve to drive a piston or the like in a work chamber to perform a task, such as driving a fastener.

[0005] In such cases, energy is extracted from a high pressure fluid source via expansion. Expansion of a gas is always associated with a reduction in pressure unless heating or additional work is performed (compression) or additional gas is added to the system.

[0006] There are air-powered nail guns that are typically attached by a tether to a pneumatic compressor and use gas under pressure to drive a reciprocating piston that then drives the nail or fastener into the material to be fastened. In the systems provided by these compressors, air is continuously supplied through a valve to keep the pressure behind the piston high enough to perform the desired drive function. This valve or another valve then allows the piston to return to a ready position for work.

[0007] Keeping the intake gas cool is important to maintain high efficiency use of compressed gas, but is difficult or impossible after many combustion cycles. This is critical to the function of the tool, as the low pressure may not be sufficient to drive the nail deep if the pressure is not maintained at a high level. This of course depends on the particular substrate, nail type, chamber volume and piston diameter implemented in a particular design.

[0008] These tools (especially the framing variants) are inefficient in their use of compressed gas. They use large amounts of air to drive each nail and return the driving piston. They therefore cannot be operated off of the compressor that provides the compressed air for any meaningful commercial use. For this reason, efficiency is typically not a primary performance indicator for these tools, since the compressor only runs a short time longer with little cost or effort for the user. Instead, power, reliability, ruggedness, compactness, and other amenities take precedence over efficiency, some of which are made possible, directly or indirectly, by the presence of a virtually unlimited supply of air from a tethered compressor.

[0009] A number of different systems have been developed to try to address at least the tethering problem.

[0010] One such system utilizes a combustible gas, such as butane, to provide an explosion to drive the operation of the tool. Such combustion systems have their own safety concerns since the tool usually includes a storage device for the combustible gas and a combustion source in close proximity to each other. Also, gas and gas cartridges tend to be expensive and only available from a select number of suppliers. Furthermore, gas cartridges become waste after use and are not always recycled. Furthermore, they typically require batteries as an ignition source. Again, when these fail, they may not be recycled, even if they are rechargeable. Furthermore, the heat and shock of the explosion tend to wear down the tool significantly, requiring frequent maintenance. Also, electrical components are prone to failure if the tool is exposed to moisture, such as rain. All of these factors add additional cost, waste, and inconvenience to the user. In addition, in fast-burn situations, performance may be compromised since the combustion gases must be vented and a fresh replenishment of properly mixed gas and air must be brought in prior to combustion. In addition, efficiency may be poor because not all of the pressure generated by the combustion replenishment is used. Furthermore, they produce gases that can be dangerous to the user's health, especially in enclosed areas.

[0011] Recently, portable pressure sources have been developed in which a container containing a pressurized fluid, such as carbon dioxide, is connected via a regulator to a tool that is traditionally driven by an air compressor. These systems allow the tool to be used in a more portable manner, without being restricted by the requirement of hose connections of a traditional setup. However, available pneumatic tools are designed for pneumatic setups where the supply of compressed air or gas is virtually unlimited. Therefore, the energy transfer and use of compressed gas is again relatively inefficient, especially in the drive mechanism.

[0012] Typically, such compressed gas driven tools are inefficient, at least because, to simplify their manufacture and assembly, they have an architecture in which one of the valves, which supplies compressed gas to the work-performing drive piston, performs two functions. As a result, for at least a short time, there is a flow path between the main pressurized fluid source and the atmosphere through the chamber in which the driven piston reciprocates. Although pressure areas are generally designed to quickly stop this flow path, there is a direct path from the high pressure source to the atmosphere, even for a short time, which wastes the energy present in this high pressure fluid and can be a significant source of inefficiency in some designs. In these established designs, even when the temporary leak path is effectively minimized, the mechanism still operates in a manner that exhausts a large amount of the full pressure gas to the atmosphere, thus wasting the gas that did not perform any work. This is thermodynamically very inefficient.

[0013] It would therefore be advantageous for the drive mechanisms of pneumatic tools to be more efficient in consuming compressed gas or high pressure fluid.

[0014] One solution to avoid tethering to a remote source of high pressure fluid, or using combustion, or inefficient use of high pressure fluid, is the valving and actuation system disclosed in the inventor's own patent NZ573990. This valving and actuation system can be used in many applications, including impact nailers for wood, concrete and related building materials. However, the same actuation and valving system can find use in many other applications, including, but not limited to, pest control, air motors, or other where highly efficient valve control is desirable.

[0015] In the NZ573990 the valve which releases high pressure fluid into the work chamber is split open by a hammer which strikes the valve open allowing fluid to enter the work chamber to perform work. This is a very efficient system with very little waste of high pressure fluid.

[0016] References herein to patents, other external documents, or other sources are generally for the purpose of providing a context for discussing features of the present invention. Unless otherwise expressly stated, the reference to such external documents shall not be construed as an admission that such documents or such sources are prior art or form part of the common general knowledge in the art in any jurisdiction. Summary of the Invention [Problem to be solved by the invention]

[0017] It is an object of the present invention to provide an improved actuation and / or valving system for high pressure fluids, to provide an improved actuation and / or valving system for high pressure fluids that is more efficient and that is powered predominantly or solely by high pressure fluids or gases, to overcome the above-mentioned shortcomings or address the above-mentioned needs, or at least to provide the public with a useful choice. [Means for solving the problem]

[0018] In a first aspect, the present invention provides an apparatus comprising: a dump chamber for receiving high pressure fluid from a high pressure fluid source; a dose chamber receiving a flow of high pressure fluid from the dump chamber via a flow path from the dump chamber to the dose chamber and having an outlet; a work chamber having an inlet end at an end thereof; a dose valve member having an annular sealing surface surrounding the inlet end; when the dose valve member is in a closed state, the sealing surface contacts the annular seat to seal the outlet, and when the dose valve member is in an open state, a gap is presented between the annular sealing surface and the seat to allow high pressure fluid to move from the outlet to the inlet; The high pressure fluid in the dump chamber resides at least in part in the device holding the dose valve member closed until the pressure of the high pressure fluid in the dump chamber is reduced, thereby allowing the high pressure fluid in the dose chamber to release the dose valve member to an open state.

[0019] Preferably, when the dose valve member is open, flow of high pressure fluid is prevented from entering the dose chamber or the dump chamber.

[0020] Preferably, when the dose valve member is open, flow of high pressure fluid is prevented from entering the dump chamber.

[0021] Preferably, the high pressure fluid entering the work chamber then performs work on a workload within the work chamber, discharging the workload from or moving it to or towards the opposite end of the work chamber.

[0022] Preferably, when the workload is driven from a first end (i.e., the inlet end) to a second end (i.e., the opposite end), there is no fluid connection available from a high pressure fluid source to the workload driving the assembly or chamber.

[0023] Preferably, the dose valve member slides linearly.

[0024] Preferably, the dose valve member slides along a linear axis parallel to the main axis of the device.

[0025] Preferably, the workload, whether captured like a piston or expelled like a projectile, slides linearly along the work chamber, parallel to the primary axis, from the inlet end to or toward the opposite distal end.

[0026] Preferably, the dump chamber, the dose chamber and the work chamber are located coaxially or parallel to the main axis.

[0027] Preferably, there is an exhaust valve at or towards the inlet end that is biased open and closes the exhaust port under actuation by high pressure fluid exiting the dose chamber.

[0028] Preferably, under the action of a bias, the exhaust port is open when the workload is at or near said opposite end.

[0029] Preferably, the exhaust valve is a piston or diaphragm that is at least partially surrounded by the dose valve.

[0030] Preferably, the dose valve is at least partially biased in a closed state.

[0031] Preferably, the dose chamber is a hollow volume radially outward or inward from the work chamber.

[0032] Preferably, the flow path is through a dose chamber.

[0033] Preferably, the flow passage is within the skirt of the dose valve.

[0034] Preferably, there is a restriction in the flow path from the dump chamber to the dose chamber, so that the dump chamber participates in the closing pressure of the dose valve even when the dose chamber is filling.

[0035] Preferably, there is a one-way valve in the flow path from the dump chamber to the dose chamber.

[0036] Preferably, the dump chamber is a hollow cylindrical volume, such as an annular chamber.

[0037] Preferably, the pressure in the dump chamber is reduced by a trigger mechanism or the like.

[0038] Preferably, the trigger mechanism dumps the pressure in the dump chamber to atmosphere.

[0039] Preferably, the workload is returned to the inlet end by a fluid cushion at the rear side, a spring at the rear or front side, or a tension member connected from the front side to or towards the inlet end.

[0040] Preferably, the actuator on the exhaust valve is a spring.

[0041] Preferably here or additionally, the actuator on the exhaust valve is a tension member connected between the workload and the exhaust valve.

[0042] Preferably, there is a relief valve to selectively dump pressure from the dose chamber to prevent operation of the device.

[0043] Preferably, there is a slow leak relief valve that releases fluid pressure from the dose chamber if the high pressure fluid supply pressure drops below the pressure in the dose chamber.

[0044] In another aspect, the present invention provides a method of operating a high pressure fluid device, comprising the steps of: filling the dump chamber with high pressure fluid; increasing a sealing pressure on the valve member by high pressure fluid acting on a rear side of the valve member to hold the valve member closed, the valve member having an annular sealing surface between an outlet from the dose chamber and an inlet to the work chamber; passing high pressure fluid through a flow passage from a dump chamber to a dose chamber; reducing pressure in the dump chamber such that high pressure fluid in the dose chamber acting on a front side of the valve member forces the valve member into an open state presenting a gap between the inlet and the outlet; The high pressure fluid then enters the work chamber from the dose chamber to perform work for a workload in the work chamber.

[0045] Preferably, the dump chamber and the dose chamber are at approximately the same pressure when filled before reducing the pressure.

[0046] Preferably, the exhaust valve is moved to a position where it closes the exhaust port from the work chamber until work for the workload is performed, at which time the exhaust port opens, for example under bias.

[0047] Preferably, the method includes the step of allowing the workload to return to the inlet end of the work chamber, with any fluid between the workload and the inlet end exiting through an exhaust port.

[0048] Preferably, the exhaust port is biased open except when high pressure fluid exits the dose chamber, thereby overcoming the bias and moving the exhaust valve to a closed position of the exhaust port.

[0049] Preferably, as the workload moves to or towards the opposite side, the dose valve member moves to a closed position.

[0050] Preferably, a trigger mechanism reduces the pressure in the dump chamber.

[0051] Preferably, the workload is returned to the inlet end by a force such as, but not limited to, a fluid cushion / pressure forcer, a compressible member on the non-work side behind the workload, and / or a tensile member on the work side in front of the workload.

[0052] Preferably, the dump chamber and the dose chamber are free to fill again when the dose valve member is in the closed position.

[0053] Preferably, here or in addition, filling the dump chamber assists in closing the dose valve member.

[0054] Preferably, the method optionally includes the step of dumping the high pressure fluid in the dose chamber to atmosphere to prevent the device from operating.

[0055] In another aspect, the invention resides in an apparatus as herein described with reference to any one or more of the accompanying drawings.

[0056] In another aspect, the invention resides in a method of operating a high pressure fluid device, as herein described with reference to any one or more of the accompanying drawings.

[0057] As used herein, the term "and / or" means "and" or "or," or both.

[0058] As used herein, "(s)" following a noun refers to the plural and / or singular form of the noun.

[0059] The term "comprise" as used herein means "consisting at least in part of." When interpreting references herein that include the term, the features preceding the term in each reference must all be present, although other features may also be present. Related terms such as "comprise" and "comprised" should be interpreted similarly.

[0060] Reference to a numerical range disclosed herein (e.g., 1 to 10) is also intended to encompass references to all rational numbers within that range (e.g., 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10) and references to any range of rational numbers within that range (e.g., 2 to 8, 1.5 to 5.5, and 3.1 to 4.7).

[0061] The entire disclosures of all applications, patents and publications, cited above and below, if any, are hereby incorporated by reference.

[0062] The present invention may also be broadly described as consisting of the parts, elements and features referred to or shown individually or collectively in the specification of this patent application, and any or all combinations of any two or more of the parts, elements or features, and where a particular integer having a known equivalent in the art to which the invention pertains is described herein, such known equivalent is deemed to be incorporated herein as if it were individually set forth.

[0063] Other aspects of the invention will become apparent from the following detailed description, given by way of example only and with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0064] A preferred form of the present invention will now be described with reference to the accompanying drawings. [Figure 1] 1 shows a vertical section through the device according to the invention in a rest state, without high pressure fluid being applied; [Diagram 2] FIG. 2 shows a view similar to FIG. 1 showing the location of the pressure safety relief valve and the supply and dump ports to the dump chamber. [Diagram 3] FIG. 2 shows a view similar to FIG. 1 showing the filled dump chamber and the flow of filling it from there to the dose chamber. [Figure 4] The next stage in FIG. 3 is shown where the dose chamber is also full. [Diagram 5] The next stage in FIG. 4 is shown where the dump chamber is evacuated. [Figure 6] The next stage in FIG. 5 is shown where the dose valve is open, allowing flow from the outlet of the dose chamber to the inlet of the work chamber. [Figure 7] The next stage in FIG. 6 is shown where the exhaust valve is closed and the work load, in this example a piston, is driven towards the opposite end of the work chamber. [Figure 8] The next stage of the workload, Figure 7, is shown at the opposite end of the work chamber. [Figure 9]The next stage in FIG. 8 is shown where the workpiece, in this example a piston, begins its return stroke along the work chamber and the exhaust valve opens. [Figure 10] The next stage in FIG. 9 is shown where the workload is returned to the valve end of the work chamber. [Figure 11] FIG. 2 is a view similar to FIG. 1 with the addition of a tensioning member to assist in returning the piston, i.e., the workload, and / or function at least in part as an exhaust valve, in which at A the piston is shown ready to return to its work position with the tensioning member under little tension, at B the piston has moved to a position where it has completed its work and the tensioning member extends between the piston and the exhaust valve and is under tension, and at C the piston is shown returning along the work chamber, at least in part, assisted by the tensioning member. [Figure 12] 1 shows an overview of some embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0065] A preferred embodiment will now be described with reference to Figures 1 to 12. The figures shown are vertical cross-sections along a major axis, so that the illustrated embodiment and its components are largely radially symmetric.

[0066] A novel pneumatic force actuated valve design utilizes a pressure dump to trigger the force actuated valve to provide highly efficient energy extraction from high pressure fluids, for example, but not limited to, air or compressed gases such as carbon dioxide. Also proposed is a novel pressure based piston return and exhaust flow control system that allows the pressure behind the workload to be vented, tightly integrated with the force actuated valve, useful in high cycle rate systems that use high pressure fluids with high efficiency.

[0067] The components and features of the device will now be described with reference to FIGS.

[0068] The device 1 receives a supply of high pressure fluid 3 from a fluid source 4. In one preferred form, the fluid source 4 is connected and integrated with the tool of which the device 1 is a part, such as, for example, a handheld nailer or fastener driver, a pest trap, a rescue floatation device launcher, a gas pulse cleaning system, or other assembly requiring the valving arrangement of the present invention. The high pressure fluid source 4 in this example is a pressurized container or tank that holds the high pressure fluid. In other embodiments, the fluid source 4 may be located remotely and fluidly connected, such as in a valve system.

[0069] High pressure fluid 3 is supplied to the dump chamber 2 either directly or through a regulator, safety valve, etc. A regulator is typically required, which in addition to its safety aspects and safety valves ensures that a constant operating pressure is supplied to the trigger system and dump chamber. Typically the high pressure fluid is in a tank or container, which holds high pressure fluid at 4500 psi or more and is regulated down to an operating pressure of, for example, about 400-600 psi. The pressure in the source of high pressure fluid can of course be as high as necessary, for example the desired volume if the device is an off-the-shelf one. The regulator or a valve downstream thereof prevents too low a pressure being supplied to the dump chamber to ensure proper operation of the device.

[0070] The dump chamber 2 is an annular volume as shown, which offers several advantages. This provides a more compact system. Furthermore, given the ring-like nature of the dose valve member 11 and that it slides linearly along the main longitudinal axis of the device, the dump chamber 2 is at least partially formed by the annular space that the dose valve member 11 slides into and out of as it moves to the closed position 13 during firing. Furthermore, having the dump chamber 2 as an annular ring volume allows for a separate exhaust valve 20 and exhaust port 21 (described below) to be located internally, preferably concentrically therein (although they may be offset from the axis of the dose valve member 11 if necessary). This provides for simplified and optimized exhaust timing and control.

[0071] Downstream of the dump chamber 2 is the dose chamber 5. The two are separated by a dose valve member 11. The dose chamber 5 is also an annular ring chamber and may also be described as a hollow cylindrical volume or space. Between the two is the dose valve member 11, which will be described shortly. Between the dump chamber 2 and the dose chamber 5 is a flow path 6. The flow path 6 may pass through the body of the dose valve member 11 or may flow through a separate flow path to the dose chamber 5, for example through one or more ports in the walls of each of these chambers, fluidly connecting these chambers. When the dump chamber 2 is filled with the working fluid 3, usually at high pressure, the dose chamber 5 may also be filled via the flow path 6. In a preferred form, the flow path is provided at least in part by the dose valve member 11, as shown in FIG. 3. Alternatively, it may be provided by a leak path around the dose valve member 11. In one form, the flow path 6 is always open between the dump chamber 2 and the dose chamber 5. However, in other configurations it may only be open when the dose valve member 11 is in a closed position sealing off the dose chamber 5 .

[0072] In a preferred embodiment, there is a restriction 25 in the flow path 6 between the dump chamber 2 and the dose chamber 5. In other embodiments, there may be a check valve or one-way valve 26 between the dose chamber and the dump chamber. In certain applications this is not necessary, but in high cycle rate applications it can be very beneficial. For example, when the pressure in the dump chamber is reduced, without the one-way valve 26 pressure could flow back from the dose chamber 5 to the dump chamber 2 and then potentially to the atmosphere. The check valve may be formed by an O-ring in a groove in the outer periphery of the dose valve member 2, which seats over a single or series of holes in the groove. Air can flow out of the holes by displacing the O-ring, but is prevented from returning through the holes, for example from the dump chamber to the dose chamber, by the O-ring. The check valve may be formed by any other means, such as a poppet valve or a ball check valve. In designs where the flow passage 6 connecting the dump chamber 2 and the dose chamber 5 does not pass through the dose valve member 11, these alternative check valve options are likely to be more suitable.

[0073] Providing this check valve provides the following advantages:

[0074] a) Rapid filling of the dose chamber in applications where fast filling is beneficial, for example in high cycle rate (<1 s cycle) applications such as fastening tools.

[0075] b) Upon triggering and dumping of the pressure in the dump chamber, not allowing the dose chamber gas to flow back into the dump chamber and then to the atmosphere. This increases the reliability of the actuation mechanism by maximizing the opening force bias and increases efficiency as less air is dumped to the atmosphere.

[0076] c) The check valve requires other safety features in some applications (additional check valves, described below).

[0077] d) In the absence of a check valve, if the trigger exhaust flow capacity exceeds the flow capacity through the dump to dose flow path 6, there may be a flow restriction through the dose valve member or another flow path connecting the dump chamber and the dose chamber.

[0078] In a preferred form, the dose chamber 5, like the dump chamber 2, is a ring-shaped or annular chamber which may also be described as a hollow cylindrical volume. In the preferred form as shown in FIG.

[0079] A safety feature is the ability to independently dump pressure from the dose chamber 5 and possibly the dump chamber 2. In this way the valve and actuation system 1 can be placed in a safe or non-operational mode. In the absence of any other lockout system of the dose valve member 11, dumping pressure at least from the dose chamber 5 will prevent firing of the dose valve member 11 and therefore the workload 17.

[0080] In a preferred form, dumping the pressure in the dose chamber 5, which also dumps the pressure in the dump chamber 2 since they are connected by a flow path, is performed sequentially, first the dose chamber and then the dump chamber, or in other controlled manner such that the pressure in the dose chamber cannot override the pressure in the dump chamber and therefore the dose valve member will remain closed and the device will not be able to fire.

[0081] As an example, if the architecture of the present invention is employed in a nail gun, dumping the pressure in the dose chamber 5 will disarm the nail gun and prevent it from firing. There may be a further lockout preventing high pressure fluid from entering the dump chamber 2 (and therefore into the dose chamber) or at least into the dose chamber even if the trigger is pulled until the operator is ready to use the tool again and restarts the tool, thus closing any safety valves from the dose chamber 5 and subsequently allowing working fluid to enter the dump chamber 2 and therefore then into the dose chamber 5, the tool or at least the device 1 being ready to operate again. Simply dumping the dump chamber 2 and not allowing further working fluid to enter it is an option, but this is unsafe as the dose chamber 5 would be armed and would then fire the work chamber 8 and any workload 17 therein. For this reason, the “power off” or “safe” function must not dump pressure from dump chamber 2, but instead must dump or release at least from dose chamber 5 only or dose chamber 5 first.

[0082] In a preferred embodiment, the central axis of the dump chamber 2 and the central axis of the dose chamber 5 are parallel to the main axis 18 of the apparatus, and in a preferred embodiment, they are all concentric, however, in some embodiments, while parallel, they may be offset from one another.

[0083] For added safety, there may be safety check valves 29A and 29B for unintentional pressure loss, a feature that may be required in fastening applications.

[0084] The first of these is a check valve 29A for catastrophic supply failure. In the extreme event that a large leak path occurs upstream of the trigger, this could lead to dump chamber 2 losing pressure. An in-line check valve from the dump chamber into dump chamber 2 would stop dump chamber 2 from dumping back through the leak and triggering a firing event. Depending on the type of housing and the integrity of the system, as well as the flow capacity of other components, this safety feature may be deemed unnecessary, but it should be a very well-thought-out decision.

[0085] The second of these is the slow leak safety check valve 29B. The dose chamber 5 must not be allowed to reach a significantly higher pressure than the dump chamber 2, as an unintentional slow leak, or normal pressure loss through the pressure supply vent, could result in a launch event. A check valve upstream of the catastrophic supply failure check valve achieves this. If the supply pressure drops below the dose chamber pressure, air will flow from the dose chamber into the leak safety check valve and eventually out the failed leak point into the atmosphere.

[0086] The trigger mechanism may utilize a spool valve that dumps the pressure in the dump chamber 2. Alternatively, a spool valve may be used that interrupts the flow of working fluid 3 to the dump chamber 2 and connects the dump chamber 2 to an exhaust to atmosphere. The spool valve may then return to a first state closing the exhaust and reconnecting the supply to the dump chamber 2. This has the effect that in the first position it supplies high pressure fluid to refill the dump chamber and the dose chamber, and then when moved to the second position it completely cuts off the supply of high pressure fluid and then connects the dump chamber to atmospheric pressure or a reference pressure or a lower pressure. This then allows the dump chamber to release its pressure and thus the dose chamber to open the dose valve and later refill the work chamber or workload 31 to perform work.

[0087] Between the dump chamber 2 and the dose chamber 5 is a dose valve member 11. The dose valve member 11 has a closed position 13 as shown in FIG. 2 and an open position 15 as shown in FIG. 7. In one form, the dose valve member 11 is biased closed. The dose valve member 11 has an annular sealing surface 12 which in a preferred form is or is substantially an obtuse or rounded knife edge as shown. The annular sealing surface 12 then seals in the closed position 13 against a sealing member 34. In a preferred form, the sealing member 34 is an O-ring, a square cross-section ring, an X-shaped (or "quad") ring, or an integral co-molded sealing element, or a rubber or rubber-like material of similar cross-section, as shown, although other forms are acceptable as long as they are able to seal as required against the sealing surface 12, and the opposite arrangement can also be utilized as described below. The sealing member 34 may be on or near the wall of the dose chamber, for example as shown in Figure 2. Alternatively, the sealing member 34 may be on the dose valve member 11 and the sealing surface 12 may be on or near the wall of the dose chamber.

[0088] When the dose valve member is in the open position 15 as shown in Figures 6 and 7, a gap 16 is presented or created or formed between the annular sealing surface 12 and the sealing member 34. This forms an outlet 7 from the dose chamber 5 to the work chamber 8. This allows working fluid under pressure to enter into the work chamber 8.

[0089] In a preferred form, the dose valve member 11 is biased closed, for example by a dose spring 35 .

[0090] The dose valve member 11 as shown has an elongated skirt 23 extending along and parallel to its linear axis 18. The elongated skirt 23 is received within the dump chamber 2 when in the open position 15. In a preferred form, the elongated skirt 23 fills the entire dump chamber 2. When in the closed position 13, the elongated skirt partially forms a wall of the annular cavity that is the dump chamber 2. Fluid pressure within the dump chamber acts on the rear face 36 of the dose valve member 11 to hold it partially closed. This fluid pressure therefore acts to urge the dump valve member 11 further into the closed position 13, increasing the seal between the annular sealing surface 12 and the sealing member 34. This may be done in conjunction with or instead of the dose spring 35.

[0091] The front face 37 of the dose valve member 11 is also subjected to pressure from the working fluid 3 in the dose chamber. However, the dose valve member is held in a closed position by this pressure and / or the area difference with the dump chamber. The dose valve member 11 then opens only when this pressure in the dump chamber is reduced. Due to the high pressure, this opening is very fast and occurs in 0.01-2 seconds, preferably less than 0.5 seconds.

[0092] In steady state situations, the pressure between the dose chamber 5 and the dump chamber 2 are substantially the same, and typically will be the same for most high speed firing situations. However, the dump chamber 2 has a larger area over which pressure acts on the rear face 36 than on the front face presented to the dose chamber 5, and therefore the dose valve member 11 remains closed. It is only when the pressure in the dump chamber 2 is reduced, dumped, vented or released, for example by a trigger system as described above, that the dose chamber 5 has sufficient force to open the dose valve member 11.

[0093] Downstream from the dose chamber 5 and its outlet 7 is a work chamber 8. The work chamber has an inlet 9 at an inlet end 10 which receives working fluid 3 from the dose chamber 5 when the dose valve member 11 moves to an open position 15.

[0094] The work chamber 8 contains a workload 17. This workload may be a captured workload, such as, but not limited to, a piston reciprocating within the work chamber, or it may be an uncaptured workload, such as a projectile ejected from the work chamber 8. Alternatively, there may not be any physical item, such as a piston or projectile, within the work chamber, and it may be a pressure wave that is ejected into or out of the chamber to perform work.

[0095] In the preferred form, the workload is preferably located at the inlet end 10 with no void or volume present behind the dose valve member 11 before it opens.

[0096] Similarly, downstream of the dose chamber 5 and dose valve member 11 is an exhaust valve 20. This exhaust valve may be upstream of the work chamber 8 or may be in the same stream position as the work chamber 8, with the working fluid 3 acting on both simultaneously or nearly simultaneously.

[0097] The exhaust valve 20 also has an open position, as shown in Figure 3, and a closed position, as shown in Figure 7. When in the open position, the exhaust valve exposes one or more exhaust ports 21 and when in the closed position, it closes them. In a preferred form, the exhaust valve 20 is biased to the open position, for example, by an exhaust spring 38, or additionally or alternatively by a tension member 28, as described below.

[0098] The exhaust valve 20 is moved to a closed position by the working fluid 3 when the dose valve member 11 is open, thus closing the exhaust port 21 and providing a closed volume in the work chamber 8 .

[0099] When the work chamber 8 is exposed to this pressurized working fluid 3, the workload therein receives energy from the working fluid and is acted upon by the working fluid, for example moving to the opposite end 22 of the work chamber 8. This workload may then be expelled therefrom, for example as a projectile, or may return, for example in the case of a piston.

[0100] As explained above, one way to return the workload to the firing position, i.e. near the dose valve end or inlet end, is to use an air cushion on the front side 31 of the workload, e.g. the front side 31 of the piston. This air cushion is formed by a return chamber 39. On the rear side too, a spring or the like can be used.

[0101] Another method, alternatively or additionally, is to use a tension member 28, for example, on the rear side 32 of a workload, such as a piston, as shown in Figures 11A-11C. The tension member 28 can be a resilient elastic element, such as, for example, but not limited to, silicone rubber or a similar material, that in its relaxed or near relaxed state holds the workload near or against the inlet end of the work chamber.

[0102] As the actuation system 1 is fired and the workload moves along the work chamber 8, the tension element 28 extends. Once the firing stroke is complete, the workload must return to the valve or inlet end 10 of the work chamber 8 and the pressure on the work or back side of the workload is reduced. The tension member will attempt to contract again, either by itself or in conjunction with an air cushion or other stored energy at the front 31 of the workload. In this way, the tension member will pull the workload back towards the inlet end 10 of the work chamber 8 while the air cushion pushes against the tension member.

[0103] Tension member 28 may be connected to the interior of work chamber 8 or may extend through the wall of the work chamber and be connected or restrained by an exterior surface, body, fixture, or fastening method.

[0104] In another form, the tension member may be connected to an exhaust valve 20, such as a seat, piston or movable element, as shown in Figures 11A-11C. The exhaust valve 20 will close the exhaust port 21 as the workload moves along the work chamber 8 upon firing, as described above. At or near the completion of the work stroke, the exhaust valve 20 is timed to open the exhaust port 21 to reduce the pressure at the front of the workload, thus facilitating a return to the starting position at the inlet end 10 of the work chamber 8.

[0105] When the tension member 28 is connected to the exhaust valve 20, the tension member 28 is adjusted to at least partially or completely control the movement of the exhaust valve 20 to assist in opening the exhaust port 21. This is an additional way to adjust and time the opening of the exhaust port 21 by applying a force to the exhaust element based on the position of the workload. This may be used to completely eliminate the piston return chamber 39 (thus reducing part count, potential for sealing failure, and / or complexity) or may provide advantages because it may eliminate some of its components, such as a one-way check valve, or at least allow for a reduction in the size of the piston return chamber 39, or allow the piston return chamber to be effectively operated at a lower pressure.

[0106] Additionally, if tension member 28 is an elastic material, at least for the elongations it will experience, it will typically reduce its cross-sectional area as it elongates and increase its cross-sectional area as it expands, as is clearly shown in Figures 11A-11C.

[0107] The tension member 28 as shown in FIG. 11 may be connected, at least in part, through the exhaust valve 20. Thus, as the tension member 28 extends, it reduces its cross-sectional area as seen in FIG. 11B, typically opening the portion of the exhaust valve 20 through which it is connected when the workload is at the extreme end of its stroke, thus work is being done by the high pressure fluid, and the workload is ready to return. The exhaust valve 20 will then open under the action described above, and optionally further by the tensioning and narrowing of the tension member 28, moving it away from the port 21 to an open position. The narrowing of the tension member 28 then allows for an additional exhaust path through the body of the exhaust valve 20, in this case the center.

[0108] This feature can also be utilized to time the opening of the exhaust valve 20 and the exhaust port 21. In this way, the linear movement required for the exhaust valve 20 to open and close the port 21 can be reduced.

[0109] The device is at least partially contained within and forms some of the described structure by a housing 33. The device has a major axis 18 extending along its major length.

[0110] The method of operation of the valve and actuation system according to the present invention will now be described with reference to Figures 1 to 10. The direction of movement of the valve, workload and working fluid 3 is indicated by arrows and the position of the working fluid is made clear using cross-hatched lines.

[0111] In Figure 3, the dump chamber 2 fills faster than the dose chamber 5, causing the dose valve member 11 to close and create or add a sealing force bias. This difference in filling rates is unavoidable because the dose chamber 5 is fed from the dump chamber 2 via a flow path 6 and any restriction 25 of the valve 26 in that flow path, and the amount of pressure difference that occurs depends on the flow capacity of the flow paths into and out of the dump chamber 2. The dose chamber 5 can also be filled through a one-way valve. In Figure 4, the dose chamber 5 is shown refilled.

[0112] 5, when the trigger mechanism 27 is actuated, the dump chamber 2 is vented or released, in this example to a lower pressure, such as atmospheric or base pressure. The balance of forces in the dose valve member 11 is exchanged by the pressure regions of the inner seal, outer seal and face seal. In another configuration, the dump chamber could vent to the work chamber 8 (which would slightly increase efficiency and partially alleviate the need to make the dose chamber 5 extremely small for efficiency).

[0113] 6, the dose chamber 5 is then opened and pressurized gas flows to fill the small space behind the work load 17, which in this example is a piston as shown. a. Further increase the opening force bias on the dose valve member 11 to open it fully, expelling any remaining gas in the dump chamber 2.

[0114] b. Energizing the exhaust valve, causing it to begin moving toward a closed position.

[0115] c. Begin moving the workload along the work chamber.

[0116] The working fluid 3 in the dose chamber 5 expands as shown in Figure 7, causing a pressure drop and pushing the workload 17 along the work chamber 8. An exhaust valve 20, which is piston shaped as shown, seals against its face seal to seal the exhaust port 21 and therefore the work chamber behind the workload.

[0117] As the work load, a piston in this example, moves it passes through the return chamber one-way valve 40 in Figure 8, allowing the work chamber pressure at the front side 31 of the work load to spread into the piston return chamber 39. If the dose valve member 11 is fitted with a force biasing spring 35 (not shown), it will close the dose valve member 11 slightly before or slightly after that time, depending on the adjustment.

[0118] 9, the exhaust pressure is reached, allowing the exhaust spring 38 to overcome the pressure force and open the exhaust valve 20, and therefore the exhaust port 21. This allows the return or charging of the working fluid 3 in the piston return chamber 39 and / or the workload driven by the tension member 28. If the dose spring 35 is included, the dose valve member 11 will move to the closed position 13 at this stage, but without this spring the dose valve member 11 will remain open and the dose chamber 5 will be fully vented to the work chamber and subsequently to atmosphere after the exhaust is opened.

[0119] The working fluid 3 remaining behind the workload 17 is exhausted to atmosphere through port 21 and the workload 17 returns to the inlet end 10 as shown in FIG.

[0120] Pulling or otherwise actuating the trigger cuts off the supply of working fluid to the firing mechanism, i.e., dump chamber 2. Then, upon release of trigger mechanism 27, dump chamber 2 and dose 5 chamber are quickly refilled. In other configurations, actuating trigger mechanism 27 momentarily cuts off the supply, but then refills dump chamber 2, even if the trigger mechanism is not released.

[0121] The release of the trigger 27 may be automated, latch-driven or spring-driven in some manner to allow reloading while the trigger is still depressed, i.e., the trigger is only effective for a short period of time, or may depend on another trigger element, such as a safety element used in nail guns that ensures that the tool is held against the workpiece as part of the triggering action.

[0122] Exhaust can occur independently of the position of the dose valve member 11 .

[0123] The present invention may have potential applications in penetration type fastening tools, pneumatic motors, projectile launchers, high velocity pulsed air or fluid valves, etc. The working fluid may be a compressed gas, preferably highly compressed using 4500 PSI or more as a source, but may also be regulated and reduced pressure, for example, air, carbon dioxide, nitrogen, etc. In alternative forms, the working fluid may be a hydraulic fluid, a supercritical fluid, etc.

[0124] The present invention offers many advantages over the prior art. The valve is highly efficient and a high percentage of the available energy can be extracted from the high pressure fluid. This allows more repetitions to be obtained from the high pressure fluid source, reducing the costs associated with refilling the source and increasing the convenience of using the motion transmission device. Due to the closed nature of the system and the large reduction in fluid pressure from the start to the end of the cycle, noise generated by the device is significantly reduced, increasing ease of use. Less pressurized fluid required per cycle, allowing more repetitions to be achieved safely. A smaller volume of pressurized fluid is discharged during evacuation of the actuation system, reducing evacuation requirements and potential safety hazards associated with this process. For example, if the pressurized fluid is carbon dioxide, the risk of dry ice being generated during evacuation is reduced. The valve opening area is large relative to the dose chamber volume and the valve area opens rapidly. Thus, the fully refilled high pressure gas leaves the dose chamber very quickly and the valve can return to a closed state immediately after opening. This allows the mechanism to operate effectively at very high cycle rates, allowing the dose and dump chambers to be refilled and ready to fire again even while the workload is moving along the chambers. Enables high power density, extremely efficient pneumatic force actuation with reliable pressure dumps, force activated seals and triggers.

[0125] The above description of the invention includes preferred forms thereof. Modifications can be made thereto without departing from the scope of the invention.

Claims

1. An apparatus comprising: a dump chamber having an annular shape and configured to receive high pressure fluid from a high pressure fluid source; a dose chamber configured to receive a flow of the high pressure fluid from the dump chamber via a flow path from the dump chamber to the dose chamber, the dose chamber having an outlet; a work chamber having an inlet at an inlet end; a dose valve member having an annular sealing surface surrounding said inlet end; when the dose valve member is in a closed state, the sealing surface abuts an annular seat to seal the outlet, and when the dose valve member is in an open state, a gap is presented between the annular sealing surface and the seat to allow high pressure fluid to move from the outlet to the inlet and to prevent flow of the high pressure fluid from entering the dose chamber or the dump chamber; The high pressure fluid in the dump chamber at least partially holds the dose valve member in the closed state until the pressure of the high pressure fluid in the dump chamber is reduced thereby causing the high pressure fluid in the dose chamber to release the dose valve member to the open state.

2. 2. The apparatus of claim 1, wherein when the dose valve member is open, flow of the high pressure fluid is prevented from entering the dump chamber.

3. The high pressure fluid entering the work chamber then performs work on a workload in the work chamber, discharging the workload from an opposite end of the work chamber or moving the workload to or towards the opposite end, or 3. The apparatus of claim 1 or 2, wherein the high pressure fluid entering the work chamber then performs work on a workload in the work chamber, discharging the workload from or moving it to or towards the opposite end of the work chamber, and wherein there is no fluid connection available from any high pressure fluid source to an assembly or chamber driving the workload as the workload is driven from a first end (or inlet end) to a second end (or opposite end).

4. An apparatus according to any one of claims 1 to 3, wherein the dose valve member is configured to slide linearly.

5. A device according to any preceding claim, wherein the dose valve member is arranged to slide along a linear axis parallel to a main axis of the device.

6. 6. The apparatus of any one of claims 3 to 5, wherein the workload, whether captured such as a piston or expelled such as a projectile, is configured to slide linearly along the work chamber from the inlet end to or towards the opposite or distal end, parallel to a major axis of the device.

7. The apparatus of any one of claims 1 to 6, wherein the dump chamber, the dose chamber and the work chamber lie coaxially or parallel to a main axis of the apparatus.

8. an exhaust valve configured to be biased open at or toward the inlet end and close an exhaust port under actuation by the high pressure fluid exiting the dose chamber; or 8. The apparatus of claim 1, wherein there is an exhaust valve configured to be biased open at or towards the inlet end and to close an exhaust port under actuation by the high pressure fluid exiting the dose chamber, and wherein the exhaust port is configured to open under the action of the bias when the workload is at or near the opposite end.

9. 9. The apparatus of claim 8, wherein the exhaust valve is a piston or a diaphragm at least partially surrounded by the dose valve member.

10. An apparatus according to any preceding claim, wherein the dose valve member is at least partially biased in the closed state.

11. An apparatus according to any preceding claim, wherein the dose chamber is a hollow volume radially outward or inward from the work chamber.

12. the flow path is through the dose valve member, or An apparatus according to any preceding claim, wherein the flow passage is through the dose valve member, the flow passage being within a skirt of the dose valve member.

13. 13. The apparatus of claim 1, wherein a restriction is present in the flow path from the dump chamber to the dose chamber, whereby the dump chamber participates in the closing pressure of the dose valve member even when filling the dose chamber.

14. a one-way valve is present in the flow path from the dump chamber to the dose chamber; or 14. The apparatus of claim 1, further comprising a check valve in a flow path from the dump chamber to the dose chamber, the check valve configured to prevent flow of the high pressure fluid from the dose chamber to the dump chamber in response to the apparatus being triggered.

15. The pressure in the dump chamber is reduced by a trigger mechanism or the like; or An apparatus as claimed in any preceding claim, wherein pressure in the dump chamber is reduced by a trigger mechanism or the like, which dumps the pressure in the dump chamber to atmosphere.

16. 16. The apparatus of claim 1, wherein the workload is returned to the inlet end by a fluid cushion at the rear side, or a spring at the rear or front side, or a tension member connected from the front side to or towards the inlet end.

17. The actuator in the exhaust valve is a spring, or 10. The apparatus of claim 8 or 9, wherein the actuator on the exhaust valve is a spring and the actuator on the exhaust valve is a tension member connected between the workload and the exhaust valve.

18. a relief valve configured to selectively dump pressure from the dose chamber to prevent operation of the device; or 18. The apparatus of claim 1, further comprising a slow leak safety valve configured to release fluid pressure from the dose chamber when the supply pressure of the high pressure fluid drops below the pressure in the dose chamber.

19. 1. A method of operating a high pressure fluid device, comprising: filling an annular shaped dump chamber with high pressure fluid; increasing a sealing pressure of a dose valve member by the high pressure fluid acting on a rear side of the dose valve member to hold the dose valve member closed, the dose valve member having an annular sealing surface between an outlet from the dose chamber and an inlet to the work chamber at an inlet end of the work chamber; passing the high pressure fluid through a flow passage from the dump chamber to the dose chamber; reducing pressure in the dump chamber whereby the high pressure fluid in the dose chamber acting on a front side of the dose valve member forces the dose valve member into an open state presenting a gap between the inlet and the outlet; preventing flow of the high pressure fluid from entering the dose chamber or the dump chamber when the dose valve member is open; the high pressure fluid then enters the work chamber from the dose chamber to perform work for a workload in the work chamber.

20. The method of claim 19, further comprising preventing a flow of the high pressure fluid from entering the dose chamber when the valve member is open.

21. 21. The method of claim 19 or 20, wherein the dump chamber and the dose chamber are at approximately the same pressure when filled before reducing the pressure. an exhaust valve is moved to a position that closes the exhaust port from the work chamber until work for the workload is performed, such that the exhaust port is open, e.g., under bias; or 22. A method according to any one of claims 19 to 21, wherein an exhaust valve is moved to a position closing the exhaust port from the work chamber until work on the workload is performed, whereby the exhaust port opens, for example under bias, and the method includes the step of allowing the workload to return to the inlet end of the work chamber, with any fluid between the workload and the inlet end exiting through the exhaust port.

23. 23. The method of claim 22, wherein the exhaust port is biased open except when the high pressure fluid exits the dose chamber, thereby overcoming the bias and moving the exhaust valve to a closed position of the exhaust port.

24. A method according to any one of claims 19 to 23, wherein the dose valve member moves to the closed position as the workload moves to or towards the opposite end.

25. A method as claimed in any one of claims 19 to 24, wherein a trigger mechanism reduces pressure in the dump chamber.

26. 26. The method of any one of claims 19 to 25, wherein the workload is returned to the inlet end by a forcer such as, but not limited to, a fluid cushion / pressure forcer or a compressible member on a rear non-work side of the workload and / or a tensile member on a front work side of the workload.

27. A method according to any one of claims 19 to 26, wherein the dump chamber and the dose chamber are free to fill again when the dose valve member is in the closed position.

28. A method according to any one of claims 19 to 27, wherein filling the dump chamber assists in closing the dose valve member.

29. The method of any one of claims 19 to 28, optionally comprising dumping the high pressure fluid in the dose chamber to atmosphere to prevent the device from operating.

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