Pressure regulator for a pre-charged pneumatic airgun

Abstract

The invention relates to a pressure regulator for a pre-charged pneumatic airgun, and comprises a housing including a regulated pressure chamber and a high-pressure inlet; a regulator piston displaceable within the housing; biasing means for biasing the regulator piston in a first direction; a first sealing member arranged within the regulated pressure chamber for opening and closing the high pressure inlet; wherein the regulator piston is displaceable in the first direction in the same direction as the biasing force of the biasing means, and wherein such displacement actuates the first sealing member to open the high-pressure inlet to allow ingress of pressurized gas into the regulated pressure chamber; and wherein such increased pressure acts upon the regulator piston; wherein the regulator piston displacement in the second direction actuates the first sealing member to close the high pressure inlet, and wherein airflow into the regulated pressure chamber is controlled perpendicularly to the axial displacement of the regulator piston.

Description

[0001] PRESSURE REGULATOR FOR A PRE-CHARGED PNEUMATIC AIRGUN

[0002] INTRODUCTION

[0003] The invention relates to a pressure regulator suitable for use on a pre-charged pneumatic airgun.

[0004] BACKRGOUND TO THE INVENTION

[0005] Airguns, or more generally, gas guns, extract energy from compressed gas to propel a projectile. There are two basic architectures to build an airgun:

[0006] • A spring piston airgun relies on a compressed spring (metallic or pneumatic) which, when the gun is fired, compresses air that drives the projectile down a barrel.

[0007] • The other fundamental architecture uses a high-pressure reservoir as a source of high-pressure air. In small, portable airguns, the reservoir is part of the gun. In large airguns, such as artillery pieces, the reservoir can physically be separate from the gun itself.

[0008] Small PCP (PCP = “Pre-Charged Pneumatic”) airguns have become extremely popular in the last few years, with their internals having evolved to a high degree of sophistication and their accuracy rivaling that of quality conventional firearms. Historically, PCP airgunshave been around for a long time and, while their most common application is in sport shooting (e.g., all modem Olympic air rifles are of the POP type), their concept also found application in warfare and hypervelocity research. In the late 1800’s, for example, the city of San Francisco (USA) was defended by a battery of POP air cannon capable of launching 500 lb. projectiles over a mile out to sea, and POP mortars were used during WWI. While modem artillery displaced POP artillery long ago, sophisticated variations on gas guns are used today to simulate the effects of micro-meteorite impacts, where extremely high velocities must be achieved.

[0009] In addition, paintball guns and airsoft guns also use compressed air, among others, as propellant, although the operating mechanisms of these types of guns tend to be very different than those used in PCP airguns due to the much lower velocities of the projectiles. This application only deals with PCP airguns shooting pellets or slugs for target or hunting purposes.

[0010] 1. Basic operation of a PCP airgun

[0011] Figure 1 (Prior art) shows the basic components of a PCP airgun with a “knock down” or “poppet” valve together with an air regulator. Most PCP’s currently in the market utilize a poppet valve or variations thereof combined with a regulator. The firing cycle of a standard PCP airgun begins when a trigger sear releases a hammer (3), which is held against a compressed hammer spring (4). The hammer (3) accelerates under the force of the hammer spring (4) and, after travelling a short distance, it strikes a valve (1) thatcommunicates with a plenum (6) (i.e., high-pressure air source), either regulated or unregulated. Upon being struck by the hammer (3), the valve (1) briefly opens, allowing a blast of high-pressure air to be routed to a transfer port (7) and from there to a breech (9), where pressure builds up and propels a pellet (8) down a barrel (5).

[0012] Velocity of the pellet (8), and hence power of the airgun, depends on - • Air pressure in the plenum (6)

[0013] • Volume of the plenum (6)

[0014] • Length and diameter (i.e., volume) of the transfer port (7)

[0015] • Time the valve (1) remains open

[0016] • Length of the barrel (5)

[0017] • Weight of the pellet (8)

[0018] In general, for an unregulated airgun (i.e., where there is no regulator present), a user can adjust the power of the gun by increasing the duration of time that the valve (1) remains open, as all other variables (apart from the pellet weight) are fixed during the design process. For a regulated airgun (i.e., where high pressure in an air reservoir (11) is reduced to a lower working pressure), power can be adjusted either by increasing pressure in the plenum (6) via the regulator (10) and / or increasing the time the valve (1) remains open. There are, however, airguns that also allow the user to change the size of the transfer port (7), and hence the volume of air that can be expelled during the firing cycle.Unregulated vs regulated airguns

[0019] Unregulated

[0020] In an unregulated PCP airgun, there is no regulator (10) present, and the valve (1) is directly connected to the high-pressure air reservoir (11). A PCP valve operates best between a certain high- and low-pressure point. The valve (1) will open and remain open long enough to pass air from the reservoir (11) to power a pellet (8) to the same velocity. When the reservoir pressure is high, it acts on the valve (1) to close it faster, but the air that passes through the valve (1) when the gun fires is under very high pressure. As a user continues to shoot and the reservoir pressure continues to drop, it acts with less force and less quickly on the valve (1) to close it, so the valve (1) remains open for slightly longer. The air that passes through the valve (1) before it closes is not pressurized as high, but since the valve (1) remains open for slightly longer, it delivers similar acceleration to the pellet (8). The result is that the pellet (8) stays at the same velocity throughout several shots.

[0021] A string of shots that are at the same velocity are referred to as the “power curve” of the gun. If the reservoir pressure is above the pressure at which this power curve begins, the shots will be slower; if the reservoir pressure is below the pressure at which the power curve ends, the shots will also be slower. A typical power curve of an unregulated airgun is shown in Figure 2. This of course is not ideal. The shots that are fired before the power curve begins are not useful to a hunter or target shooter, nor are the shots after the power curve ends. This reduction in useful shotsdoes not utilize all of the available air in the reservoir (11). As evidenced by the curve in Figure 2, there are only about twelve good shots in this illustrated gun, and even those good shots have quite a large variation between them.

[0022] 2.2 Regulated

[0023] In a regulated PCP airgun, a regulator (10) is installed between the high-pressure air reservoir (11) and the plenum (6) and reduces the pressure to a nearly constant pressure in the plenum (6). The result is a consistent and repeatable movement of the valve (1) as the forces acting on the valve (1) during the firing cycle are consistent from shot to shot, resulting in a consistent pellet velocity from shot to shot. A regulator (10) also increases the number of useful shots as the gun can now utilize all available air in the reservoir (11) until it goes off the regulator (i.e. , the gun goes off the regulator when the reservoir pressure is less than the pressure setpoint in the regulated chamber / plenum). The regulator (10) also decreases variation in pellet velocity from shot to shot, increasing the consistency and hence accuracy of the gun. For this reason, quality airguns are nearly always of the regulated kind as consistent pellet velocity from shot to shot greatly affects accuracy, which is the holy grail of airguns.

[0024] 3. History of airgun regulators

[0025] The history of airgun regulators traces back to the development of modem airguns and the quest for improved consistency and efficiency in performance. Regulators aredevices used in PCP airguns to manage and stabilize the pressure of air supplied to the firing mechanism / valve as explained above. Airguns have been around since the 1600s, with some early designs using compressed air stored in reservoirs to propel projectiles. Examples include the Girandoni air rifle, used in the late 18thcentury. These early airguns lacked any sophisticated mechanism to regulate air pressure. Instead, the performance varied significantly as the reservoir pressure decreased with each shot.

[0026] During the mid-20thcentury PCP airguns became more common. They relied on high-pressure reservoirs for repeated shots, but consistency remained a challenge. Some airguns incorporated basic mechanisms for adjusting airflow manually, but these were not true regulators. At the end of the 20thcentury, as the demand for more accurate and consistent airguns grew, manufacturers and hobbyists began designing regulators to stabilize the pressure. Early regulators for airguns were adaptations of industrial pressure-regulating technology. These were simple devices designed to ensure a steady flow of air to the firing valve regardless of the reservoir pressure.

[0027] Today, regulators are a standard feature in many high-end PCP airguns. They ensure consistent velocity for each shot, improving accuracy and extending the usable pressure range of the reservoir. Modem regulators are compact, efficient, and highly adjustable. They use sophisticated materials and designs to minimize wear and optimize performance. Some regulators now work in tandem with electronic systems to further enhance performance and efficiency.The impact of regulators on airgun shooting addresses two highly desirable characteristics:

[0028] • Accuracy: Regulators have revolutionized airgun shooting by providing consistent shot-to-shot velocities, which is crucial for precision sports like field target and benchrest shooting.

[0029] • Efficiency: By optimizing air usage, regulators allow shooters to get more shots per fill, making airguns more practical and economical to use.

[0030] The development of airgun regulators reflects a broader trend in airgun technology toward greater precision, efficiency, and user control. From crude beginnings to sophisticated modem devices, regulators have played a key role in making PCP airguns the highly capable tools they are today.

[0031] 4. Shortcomings associated with prior art regulators

[0032] As explained hereinbefore, regulators have greatly improved a user’s experience with airguns. However, apart from smaller issues such as temperature sensitivity (i.e., changes in pressure associated with temperature changes in the environment), and wear and tear on seals and other materials (i.e., caused by extended use without proper maintenance or over pressurization), there are four fundamental shortcomings associated with prior art regulators, namely - • Drop in regulated pressure as the reservoir pressure drops

[0033] Variation in regulated pressure from shot to shotInability to decrease the regulated pressure without damaging the sealing surfaces.

[0034] • Regulator Creep

[0035] 4.1 Drop in regulated pressure as the reservoir pressure drops

[0036] Figure 3 shows the basic design of a prior art airgun regulator. The regulator consists of two chambers, a high-pressure chamber (1) and a low (secondary) pressure chamber (2). The two chambers are interconnected by a channel (5) through a piston (3) which allows air to flow from the high-pressure chamber (1) to the low-pressure chamber (2) when a piston edge (6) is lifted from a valve seat (4) by spring (7).

[0037] When a shot is fired, air from the plenum, or secondary pressure (2) in the diagram, is directed by a valve (not shown) into the airgun barrel (not shown) (refer Figure 1). The flow of air from the plenum into the barrel causes the secondary pressure (2) to drop. When the secondary pressure (2) drops, the spring (7) moves the piston (3) forward. This forward motion lifts the piston edge (6) from the valve seat (4), allowing high pressure air to flow through the channel (5) into the plenum or secondary pressure chamber (2). As airflows into the plenum or secondary pressure chamber (2) the pressure in the plenum rises and a pneumatic force acts on the piston (3). The rising pneumatic force opposes the spring force and eventually overcomes the spring force as air continues to flow into the plenum or secondary pressure chamber (2). When this occurs, the pneumatic force pushes the piston back against the spring (7) until it presses the piston edge (6) onto the valve seat (4), cutting off flowof air from the high-pressure chamber (1) into the low-pressure chamber (2). Secondary pressure is controlled by force in the spring: the higher the force in the spring, the higher the secondary pressure (2) and the lower the force in the spring, the lower the secondary pressure (2).

[0038] As shown in Figure 3, the edge (6) is exposed to high-pressure air when the regulator opens. The piston edge (6) has a very small surface area formed between the outside diameter and inside diameter of the piston (3). The high pressure (1) will act on this small area and exert a pneumatic force on the piston edge (6). This force is in the same direction as the force of the spring (7) and opposes the pneumatic force on the piston from the secondary pressure chamber (2). When the high pressure (1) is very high, the pneumatic force on the edge (6) will be high and when the high pressure (1) is low, the pneumatic force on the edge (6) will be low. As a result, the regulated pressure in the secondary pressure chamber (2) will drop as the high pressure (1) drops. This drop in pressure over the range of the regulator will cause a drop in pellet velocity as the air reservoir pressure drops. As the area of the edge (6) is small, the change in secondary pressure (2) is small, but very noticeable and problematic in quality airguns.

[0039] Some airguns try to compensate for this drop in secondary pressure (2) as the air reservoir pressure drops by installing two regulators in series, thereby supplying the final regulator with a more constant high pressure. This practice alleviates theproblem but does not eliminate it. It also increases the cost and complexity of the airgun.

[0040] Finally, the configuration shown in Figure 3 is not externally adjustable and the user must disassemble the regular and change the spring if the user wants to change the secondary pressure (2). This is time-consuming and not very practical. Figure 4 shows a variation of the regulator shown in Figure 3. The regulator shown in Figure 4 is externally adjustable and functions in much the same way as the regulator illustrated in Figure 3. However, in this case the pneumatic force exerted by the high-pressure air on the piston tail (11) is much greater due to the greater area of the piston tail (11), and variation in regulated pressure will increase as the high-pressure air in the reservoir decreases, negatively affecting the pellet velocity over the shot string as the last shots will be slower than the first shots.

[0041] Variation in regulated pressure from shot to shot

[0042] The piston (1) and disc springs (2) form an undamped spring-mass system. The lack of external damping of this system can lead to oscillations in the piston on opening and closing. These oscillations will be slightly different from shot to shot and the piston will cut the airflow slightly differently with each shot. The net effect of the piston oscillations is a slight variance in the regulated pressure from shot to shot and as a result, variance in the pellet velocity.Although there is no external damping, most regulators use either or both of the following to damp the spring-mass system:

[0043] Stick-slip friction between a piston seal (8) and housing (13)

[0044] Stick-slip friction is a damping method that leverages the alternating phases of static and kinetic friction between two surfaces. When relative motion begins, the system must overcome static friction, which is higher than kinetic friction. When the surfaces slip, energy is dissipated as heat and oscillations are reduced. This motion will eventually stop as the static friction overcomes the kinetic friction and the process repeats itself. This movement is visible on a graph as a series of ever decreasing steps. The net effect in the regulator is that the piston does not oscillate, but never comes to rest at the same position, allowing slightly more or slightly less air into the plenum, increasing or decreasing the regulated pressure slightly with each shot.

[0045] Hysteretic damping in the disc spring stack (2)

[0046] Hysteretic damping in a disc spring stack (2) refers to energy dissipation that occurs due to internal material deformation as the springs are cyclically loaded and unloaded. This damping arises from the intrinsic viscoelastic or plastic behavior of the spring material, which causes a lag between the applied force and the resulting deformation. In a stack of disc springs, the combined nonlinear load-deformation characteristics amplify the hysteresis effect, resulting in effective energy dissipation. However, the small size of mostregulators does not allow effective damping considering the high forces, and small oscillations can remain.

[0047] The combined effect of stick-slip friction between a piston seal (8) and housing (13), and hysteretic damping in the disc spring stack (2), are that modem precision regulators can maintain ± 1-2 bar pressure consistency and ± 1-5 fps (i.e., fps = “feet per second”) velocity consistency under optimal conditions (well maintained and lubricated). This is a regulated pressure spread of 2-4 bars, and a pellet velocity spread of between 2-10 fps. These spreads, and sometimes even higher, are very common in most quality airguns and can result in extreme velocity spreads over a string of shots.

[0048] Inability to decrease the regulated pressure without damaging the sealing surfaces. As seen in Figure 4, the regulator will be closed when the seal (3) is forced by the pneumatic force in the plenum, acting on the piston face (10), onto the needle face (12) against the spring force in the disc springs (2). Should the user want to increase pressure in the plenum, an adjustable needle (4) can be screwed outward. By screwing the adjustable needle (4) outward, the seal (3) and needle face (12) will separate, allowing high pressure air into the plenum, increasing the regulated pressure. The increased regulated pressure will act on the piston face (10), pushing the piston (1) to the right. As the adjustable needle has also moved to the right due to being screwed out, the piston (1) needs to travel further to the right against the increasing spring force in the disc springs (2). High pressure airflow is cut off whenthe seal (3) pushes against the needle face (12). The result is an increase in plenum pressure.

[0049] However, should the user want to decrease pressure in the plenum, the adjustable needle (4) must be screwed inward to reduce travel of the piston (1) and hence reduce the opposing force on the disc springs (2), resulting in lower pressure in the plenum. However, when the regulator is closed, the seal (3) is pushed against the needle face (12) by the pneumatic force in the plenum acting on the piston face (10), and screwing the adjustable needle (4) inward is opposed by the large pneumatic force acting on the piston face (10). Screwing the adjustable needle (4) inward will thus lead to damage of the seal (3), severely affecting its ability to seal and damaging the regulator. Accordingly, lowering the plenum pressure can only be achieved by degassing the plenum, then screwing the adjustable needle (4) inward, followed by reapplying the high pressure. This is cumbersome and not user friendly, especially considering the high priority airgun enthusiast place on field adjustability.

[0050] Regulator Creep

[0051] Regulator creep refers to the inability of the regulator to provide effective sealing between the seal (3) and the needle face (12) due to damage (over pressure or reducing the pressure) or lack of maintenance. As a result, the regulated pressure will slowly increase over time. This is problematic as a gun left for a couple of hours could have a plenum pressure much higher than that intended by the user. This will result in a higher pellet velocity for the first shot and sometimes even the secondand third shot and will affect accuracy. It is good practice to not use the first couple of shots, to give the regulator time to “settle”. This reduces shot count. It is also not desirable when hunting, as the needless first shot can startle a target. This problem has largely been solved by modem regulators with the use of more advanced materials being used for the seal (3) but can still occur due to the reasons indicated above.

[0052] 5. Other uses or regulators in gas powered guns

[0053] Paintball guns also rely on regulators to regulate the high reservoir pressure to that reguired by the paintball marker operating mechanism. However, they are fundamentally different from airgun regulators in the following:

[0054] • Airgun Regulators: Prioritize extreme consistency, precision, and adjustability, making them ideal for applications like competitive shooting and hunting.

[0055] • Paintball Regulators: Prioritize robustness, high flow rates, and reliability under rapid-fire conditions, suiting the fast-paced nature of paintball.

[0056] SUMMARY OF THE INVENTION

[0057] The invention relates to a pressure regulator suitable for use on a pre-charged pneumatic airgun wherein the pressure regulator is arranged between a plenum and a source of compressed gas, the pressure regulator comprising - a tubular housing including -a regulated pressure chamber that is arranged in air flow communication with the plenum, and

[0058] a high-pressure inlet extending through a housing wall into the regulated pressure chamber for directing ingress of high-pressure air from the source of compressed gas into the regulated pressure chamber;

[0059] a tubular regulator piston coaxially mounted, and slidingly displaceable, within the housing between a first axial direction and an opposite second axial direction;

[0060] biasing means for biasing the regulator piston resiliently in the first axial direction; a first sealing member being arranged within the regulated pressure chamber for alternately opening and closing the high-pressure inlet against the housing wall, the first sealing member being positioned radially between the regulator piston and the housing wall and being actuated between an open and closed position through displacement of the regulator piston;

[0061] wherein the regulator piston is displaceable in the first axial direction in the same direction as the biasing force of the biasing means under influence of a pressure decrease in the regulated pressure chamber, and wherein such regulator piston displacement in the first direction actuates the first sealing member to open the high-pressure inlet to allow ingress of pressurised gas from the source of compressed gas into the regulated pressure chamber; and wherein such increased pressure from the high-pressure inlet acts upon the regulator piston to exert a pneumatic force on the regulator piston in an opposite direction as the biasing force of the biasing means to displace the regulator piston against the biasing force of the biasing means in a second opposite direction; and wherein suchregulator piston displacement in the second direction actuates the first sealing member to close the high-pressure inlet, and

[0062] wherein airflow into the regulated pressure chamber is controlled perpendicularly to the axial displacement of the piston regulator.

[0063] The first sealing member may radially be displaceable relative to the regulator piston. In particular, displacement of the regulator piston in the first axial direction may radially displace the first sealing member to open the high-pressure inlet, while displacement of the regulator piston in the second axial direction may radially displace the first sealing member to close the high-pressure inlet. In one embodiment of the invention, the first sealing member may angularly be displaceable relative to the axial displacement direction of the regulator piston.

[0064] The pressure regulator further may comprise - a regulated pressure outlet for directing egress of high-pressure air from the regulated pressure chamber to atmosphere through the housing; and

[0065] a second sealing member for alternately opening and closing the regulated pressure outlet and which is actuated between an open and closed position through movement of the regulator piston.

[0066] The second sealing member may be arranged within the regulated pressure chamber, positioned radially between the regulator piston and the housing wall. The second sealing member may radially be displaceable relative to the regulator piston. In one embodimentof the invention, the second sealing member may angularly be displaceable relative to the axial displacement direction of the regulator piston.

[0067] The housing may include a guiding ridge extending radially inwardly from the housing wall into the regulated pressure chamber and positioned for guiding the first and second sealing members between the open and closed positions through movement of the regulator piston. The guiding ridge may include a first angularly disposed guiding face that cooperates with the first sealing member; and a second, oppositely angularly disposed guiding face that cooperates with the second sealing member. Particularly, the first angled guiding face of the guiding ridge guides the first sealing member to open the high-pressure inlet when the regulator piston is displaced in the first direction, and guides the first sealing member to close the high-pressure inlet when the regulator piston is displaced in the second, opposite direction. The second angled guiding face of the guiding ridge guides the second sealing member to open the regulated pressure outlet when the regulator piston is displaced in the second direction, and guides the second sealing member to close the regulated pressure outlet when the regulator piston is displaced in the first direction.

[0068] The pressure regulator may include an open-ended tubular housing cap which is removably insertable into an open end of the tubular housing, and which defines the guiding ridge, such that displacement of the regulator piston in the first direction is limited by the housing cap.The housing further may include a locating groove extending coaxially with the regulator piston within an interior wall of the housing and configured for receiving a complimentarily configured piston guide, such as a locating screw or pin, extending radially outwardly from the regulator piston for axially guiding the regulator piston in the first and second directions within the housing, but preventing rotation of the regulator piston within the housing to ensure consistently accurate location of the piston relative to the high-pressure inlet and the regulated pressure outlet.

[0069] Both the first and second sealing members may be leaf springs.

[0070] The biasing means may be a disc spring stack.

[0071] The pressure regulator may externally be adjustable and may include a rotatable adjustment screw for externally increasing pressure in the regulated pressure chamber by rotating the adjustment screw in a first direction, and externally decreasing pressure in the regulated pressure chamber by rotating the adjustment screw in a second opposite direction. In one embodiment of the invention, the adjustment screw is coaxially aligned with and seated against the disc spring stack. In an alternative embodiment of the invention, the adjustment screw is perpendicularly orientated relative to the disc spring stack and cooperates with an angled nut e which moves up and down when the perpendicular adjustment screw is turned in or out, the arrangement being such that by turning the perpendicular screw in or out, the angled nut acts on the disc spring stackthough the corresponding angle on the adjustment piston, and which increase or decrease the biasing force in the disc spring stack.

[0072] Pressure in the regulated pressure chamber is increased by rotating the adjustment screw in a first direction, thereby increasing the biasing force in the disc spring stack to a force which is greater than the opposing pneumatic force in the regulated pressure chamber, thus forcing the regulator piston in the first direction, which in turn actuates the first sealing member against the guiding ridge to the open position to allow ingress of high-pressure gas through the high-pressure inlet into the regulated pressure chamber. As pressure increases in the regulated pressure chamber, the pneumatic force acting on the regulator piston increases, opposing and eventually overcoming the biasing force in the disc spring stack, thus pushing the regulator piston in the second opposite direction, which in turn actuates the first sealing member against the guiding ridge to the closed position to block ingress of high-pressure gas into the secondary chamber, resulting in higher pressure in the regulated pressure chamber.

[0073] Conversely, pressure in the regulated pressure chamber is decreased by rotating the adjustment screw in a second, opposite direction, thereby decreasing the biasing force in the disc spring stack to a force which is less than the opposing pneumatic force in the regulated pressure chamber, thus forcing the regulator piston in the second direction which in turn actuates the second sealing member against the guiding ridge to the open position, allowing regulated air pressure to escape from the regulated pressure chamber through the regulated pressure outlet. As air escapes from the regulated pressurechamber, the pneumatic force acting on the regulator piston decreases to a point where the force in the disc spring stack eventually overcomes the pneumatic force, thus pushing the regulator piston in the first direction. As the regulator piston is being pushed in the first direction, the second sealing member is actuated against the guiding ridge to the closed position to close the regulated pressure outlet and stop the flow of air, resulting in lower pressure in the regulated pressure chamber.

[0074] The pressure regulator further may include an active hydraulic damping system adapted for reducing regulator piston oscillations, the damping system being coaxially aligned with the regulator piston and comprising - a dashpot chamber A and a dashpot chamber B, both filled with hydraulic fluid, an oil channel for fluidly connecting dashpot chambers A and B; and

[0075] a stationary dashpot piston which is secured to the adjustment screw, and which separates dashpot chambers A and B,

[0076] the arrangement being such that displacement of the regulator piston in the first direction under the biasing force from the disc spring stack increases volume in dashpot chamber A and decreases volume in dashpot chamber B, forcing hydraulic fluid from dashpot chamber B through the oil channel into dashpot chamber A, while displacement of the regulator piston in the second direction under the pneumatic force of the high-pressure inlet decreases volume in dashpot chamber A and increases volume in dashpot chamber B, forcing hydraulic fluid from dashpot chamber A through the oil channel into dashpot chamber B, thereby providing effective oil damping to the regulator piston and thus reducing piston oscillations.The regulator piston may include a radially outwardly extending piston flange that slidingly engages an interior of the housing wall and that defines a piston front face which is orientated towards, and exposed to regulated pressure from, the regulated pressure chamber; and an opposite piston rear face which is orientated towards the disc spring stack and exposed to regulated pressure by means of at least one, but preferably a number of, air channels extending coaxially through the piston flange, the arrangement being such that pressurised air flow from the regulated pressure chamber through the air channels exposes the piston rear face to regulated air pressure which reduces the pneumatic force required to oppose the biasing force in the disc spring stack. In doing so, the maximum regulated air pressure can be increased without damaging the disc spring stack while maintaining a compact size in the disc spring stack (i.e. , use of smaller springs to achieve higher pressures).

[0077] SPECIFIC EMBODIMENT OF THE INVENTION

[0078] Without wishing to be bound thereto, the invention will now further be described by way of non-limiting examples only and with reference to the following drawings in which:

[0079] FIGURE 1 (PRIOR ART) illustrates basic components of a POP airgun;

[0080] FIGURE 2 (PRIOR ART) illustrates a typical power curve of an unregulated airgun; FIGURE 3 (PRIOR ART) illustrates the basic design of an airgun regulator;

[0081] FIGURE 4 (PRIOR ART) illustrates a variation of the airgun regulator of Figure 3;FIGURE 5 is a sectional side elevation of an airgun regulator according to the invention with the regulator in a closed position;

[0082] FIGURE 6 is a sectional side elevation of the airgun regulator of Figure 5 with an inlet leaf spring and seal in an open position;

[0083] FIGURE 7 is a sectional side elevation of the airgun regulator of Figures 5 and 6 with the outlet leaf spring and seal in an open position;

[0084] FIGURE 8 is a perspective view at a one angle of rotation of the airgun regulator of the invention;

[0085] FIGURE 9 is a perspective view at a different angle of rotation of the airgun regulator of Figure 8 with the regulator positioned within its housing; and

[0086] FIGURE 10 is a sectional side elevation of an airgun regulator according to the invention illustrating an alternative embodiment where the coaxial adjustment screw and knob are replaced by an angled nut and adjustment piston with corresponding angle. The angled nut moves up and down when a perpendicular screw is turned in or out adjusting the bias of the disc spring stack.

[0087] Unless otherwise defined, all the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. The terms “first,” “second,” etc., which are used in the present application for disclosure, are not intended to indicate any sequence, amount or importance, but only distinguish various components. Also, the terms such as “a,” “an,”etc., are not intended to limit the amount, but indicate the existence of at least one. The terms “comprise,” “comprising,” “include,” “including,” etc., are intended to specify that the elements or the objects stated before these terms encompass the elements or the objects and equivalents thereof listed after these terms, but do not preclude the other elements or objects. The phrases “connect”, “connected”, “connecting”, etc., are not intended only to define a physical connection or mechanical connection, but may include an electrical connection, directly or indirectly. “On,” “under,” “right,” “left”, “atop”, and the like are only used to indicate relative position relationship, and when the position of the object which is described is changed, the relative position relationship may be changed accordingly.

[0088] A pressure regulator according to the invention is illustrated in Figure 5. The regulator aims to overcome, or at least minimise, the shortfalls associated with prior art airgun regulators, as discussed in par. 4 in the Background to the Invention.

[0089] Regulator structure

[0090] The pressure regulator according to the invention comprises a tubular housing (7) which includes a regulated pressure chamber (26) that is arranged in air flow communication with an airgun plenum, and a high-pressure inlet (14) extending through a housing wall into the regulated pressure chamber (26) for directing ingress of high-pressure air from a source of compressed gas into the regulated pressure chamber (26). The regulator further comprises a tubular regulator piston (1) which is coaxially mounted, and slidingly displaceable, within the housing (7) between a first axial direction and an opposite secondaxial direction; and biasing means (10) for biasing the regulator piston (1 ) resi I iently in the first axial direction. The regulator further comprises a first sealing member (2) which is arranged within the regulated pressure chamber (26) for alternately opening and closing the high-pressure inlet (14) against the housing wall, the first sealing member (2) being positioned radially between the regulator piston (1) and the housing wall and being actuated between an open and closed position through displacement of the regulator piston (1).

[0091] The regulator piston (1) is displaceable in the first axial direction in the same direction as the biasing force of the biasing means (10) under influence of a pressure decrease in the regulated pressure chamber (26), wherein such regulator piston (1) displacement in the first direction actuates the first sealing member (2) to open the high-pressure inlet (14) to allow ingress of pressurised gas from the source of compressed gas into the regulated pressure chamber (26); and wherein such increased pressure from the high-pressure inlet (14) acts upon the regulator piston (1) to exert a pneumatic force on the regulator piston (1) in an opposite direction as the biasing force of the biasing means (10) to displace the regulator piston (1) against the biasing force of the biasing means (10) in a second opposite direction. Such regulator piston (1) displacement in the second direction actuates the first sealing member (2) to close the high-pressure inlet (14).

[0092] The first sealing member (2) is radially displaceable relative to the regulator piston (1). In the illustrated embodiment of the invention, the first sealing member (2) is angularly displaceable relative to the axial displacement direction of the regulator piston (1).The pressure regulator further comprises a regulated pressure outlet (15) for directing egress of high-pressure air from the regulated pressure chamber (26) to atmosphere through the housing (7); and a second sealing member (3) for alternately opening and closing the regulated pressure outlet (15) and which is actuated between an open and closed position through movement of the regulator piston (1). The second sealing member (3) is arranged within the regulated pressure chamber (26), positioned radially between the regulator piston (1) and the housing wall. The second sealing member (3) is radially displaceable relative to the regulator piston (1). In the illustrated embodiment of the invention, the second sealing member (3) is angularly displaceable relative to the axial displacement direction of the regulator piston (1).

[0093] The housing (7) includes a guiding ridge (18) extending radially inwardly from the housing wall into the regulated pressure chamber (26) and positioned for guiding the first and second sealing members between the open and closed positions through movement of the regulator piston (1). The guiding ridge (18) includes a first angularly disposed guiding face that cooperates with the first sealing member (2); and a second, oppositely angularly disposed guiding face that cooperates with the second sealing member (3). Particularly, the first angled guiding face of the guiding ridge (18) guides the first sealing member (2) to open the high-pressure inlet (14) when the regulator piston (1) is displaced in the first direction, and guides the first sealing member (2) to close the high-pressure inlet (14) when the regulator piston (1) is displaced in the second, opposite direction. The second angled guiding face of the guiding ridge (18) guides the second sealing member (3) toopen the regulated pressure outlet (15) when the regulator piston (1) is displaced in the second direction and guides the second sealing member (3) to close the regulated pressure outlet (15) when the regulator piston (1) is displaced in the first direction.

[0094] The pressure regulator includes an open-ended tubular housing cap (8) which is removably insertable into an open end of the tubular housing (7), and which defines the guiding ridge (18), such that displacement of the regulator piston (1) in the first direction is limited by the housing cap (8).

[0095] The housing (7) further includes a locating groove (26) extending coaxially with the regulator piston (1) within an interior wall of the housing (7) and configured for receiving a complimentarily configured piston guide (24), such as a locating screw or pin, extending radially outwardly from the regulator piston (1) for axially guiding the regulator piston (1) in the first and second directions within the housing (7), but preventing rotation of the regulator piston (1) within the housing (7) to ensure consistently accurate location of the piston relative to the high-pressure inlet (14) and the regulated pressure outlet (15).

[0096] In the illustrated embodiment the first sealing member (2) is an inlet leaf spring and seal, and the second sealing member (3) is an outlet leaf spring and seal. The biasing means (10) is a disc spring stack.

[0097] Referring to Figures 5 - 9, the pressure regulator is externally adjustable and includes a rotatable adjustment screw (6) and adjustment knob (12) which is seated against the discspring stack (10) for externally increasing pressure in the regulated pressure chamber (26) by rotating the adjustment screw (6) in a first direction, and externally decreasing pressure in the regulated pressure chamber (26) by rotating the adjustment screw (6) in a second opposite direction. In particular, pressure in the regulated pressure chamber (26) is increased by rotating the adjustment screw (6) in the first direction, thereby increasing the biasing force in the disc spring stack (10) to a force which is greater than the opposing pneumatic force in the regulated pressure chamber (26), thus forcing the regulator piston (1) in the first direction, which in turn actuates the first sealing member (2) against the guiding ridge (18) to the open position to allow ingress of high-pressure gas through the high-pressure inlet (14) into the regulated pressure chamber (26). As pressure increases in the regulated pressure chamber (26), the pneumatic force acting on the regulator piston (1) increases, opposing and eventually overcoming the biasing force in the disc spring stack (10), thus pushing the regulator piston (1) in the second opposite direction, which in turn actuates the first sealing member (2) against the guiding ridge (18) to the closed position to block ingress of high-pressure gas into the secondary chamber, resulting in higher pressure in the regulated pressure chamber (26).

[0098] Conversely, pressure in the regulated pressure chamber (26) is decreased by rotating the adjustment screw (6) in a second, opposite direction, thereby decreasing the biasing force in the disc spring stack (10) to a force which is less than the opposing pneumatic force in the regulated pressure chamber (26), thus forcing the regulator piston (1) in the second direction which in turn actuates the second sealing member (3) against the guiding ridge (18) to the open position, allowing regulated air pressure to escape from the regulatedpressure chamber (26) through the regulated pressure outlet (15). As air escapes from the regulated pressure chamber (26), the pneumatic force acting on the regulator piston (1) decreases to a point where the force in the disc spring stack (10) eventually overcomes the pneumatic force, thus pushing the regulator piston (1) in the first direction. As the regulator piston (1) is being pushed in the first direction, the second sealing member (3) is actuated against the guiding ridge (18) to the closed position to close the regulated pressure outlet (15) and stop the flow of air, resulting in lower pressure in the regulated pressure chamber (26).

[0099] In an alternative embodiment of the invention, illustrated in Figure 10, the adjustment screw (6) is perpendicularly orientated relative to the disc spring stack (10) and cooperates with an angled nut (28) which moves up and down when the perpendicular adjustment screw (6) is turned in or out, the arrangement being such that by turning the perpendicular screw (6) in or out, the angled nut (28) acts on the adjustment piston (27) with a corresponding angle through the angled surface (30), increasing or decreasing the biasing force in the disc spring stack (10), The effect is the same as if the coaxial adjustment screw is being turned in or out. This embodiment makes the regulator adaptable to thousands of airguns already in the market where the adjustment knob (12) is not accessible from the outside. In these guns, the regulator is placed inside the air reservoir (not shown), and the setting must be guessed before assembly of the gun. This embodiment allows the regulator to be installed in the air reservoir, while still being adjustable from the outside through a small, sealed opening in the air reservoir.The pressure regulator further includes an active hydraulic damping system adapted for reducing regulator piston (1 ) oscillations, the damping system being coaxially aligned with the regulator piston (1 ) and comprising a dashpot chamber A (21 ) and a dashpot chamber B (22), both filled with hydraulic fluid; an oil channel (23) for fluidly connecting dashpot chambers A and B; and a stationary dashpot piston which is secured to the adjustment screw (6), and which separates dashpot chambers A and B. The arrangement is such that displacement of the regulator piston (1) in the first direction under the biasing force from the disc spring stack (10) increases volume in dashpot chamber A (21) and decreases volume in dashpot chamber B (22), forcing hydraulic fluid from dashpot chamber B (22) through the oil channel (23) into dashpot chamber A (21), while displacement of the regulator piston (1) in the second direction under the pneumatic force of the high-pressure inlet (14) decreases volume in dashpot chamber A (21) and increases volume in dashpot chamber B (22), forcing hydraulic fluid from dashpot chamber A (21) through the oil channel (23) into dashpot chamber B (22), thereby providing effective oil damping to the regulator piston (1) and thus reducing piston oscillations.

[0100] The regulator piston (1) includes a radially outwardly extending piston flange (27) that slidingly engages an interior of the housing wall and that defines a piston front face (16) which is orientated towards, and exposed to regulated pressure from, the regulated pressure chamber (26); and an opposite piston rear face (17) which is orientated towards the disc spring stack (10) and exposed to regulated pressure by means of at least one, but preferably a number of, air channels (25) extending coaxially through the piston flange(27), the arrangement being such that pressurised air flow from the regulated pressure chamber (26) through the air channels (25) exposes the piston rear face (17) to regulated air pressure which reduces the pneumatic force required to oppose the biasing force in the disc spring stack (10). In doing so, the maximum regulated air pressure can be increased without damaging the disc spring stack (10) while maintaining a compact size in the disc spring stack (10) (i.e. , use of smaller springs to achieve higher pressures).

[0101] Comparison to prior art regulators

[0102] The regulator of the invention comprises a number of significant structural differences of prior art regulators, which is comparatively summarized as follows:

[0103]

[0104]

[0105] Specifically, in the regulator of the invention, incoming high-pressure air (14) does not have a piston surface area to act on, and only regulated pressure can act on areas that oppose the disc spring stack (10). High pressure air is allowed into the regulated pressure chamber (26) by the inlet leaf spring and seal (2) that is opened when the piston (1 ) moves forward and is closed by the tension in the leaf spring and seal (2) when the piston (1) is forced back by the increasing pressure in the regulated pressure chamber (26) (plenum). Hence a change in pressure in the high-pressure reservoir cannot introduce a small drop in the regulated air pressure as the reservoir pressure drops.

[0106] The regulator employs an active oil damping system (4; 21 ; 22; 23) which, combined with the natural hysteretic damping of the disc spring stack (10), eliminates piston oscillations. This ensures the piston (1) consistently returns to the same starting position. As a result, the inlet leaf spring and seal (2) always closes the high-pressure inlet (14) at the exactposition, maintaining consistent compression of the disc spring stack (10) and delivering a highly stable regulated pressure from shot to shot.

[0107] In addition to an inlet leaf spring and seal (2), the regulator also features an outlet leaf spring and seal (3). When the adjustment knob (12) is turned outward, tension in the disc spring stack (10) decreases. This reduction in tension causes the piston (1) to move further to the right under the pneumatic force exerted by the regulated pressure on the piston front face (16), lifting the outlet leaf spring and seal (3) from its seat as it contacts the angled face of the guiding ridge (18). This action allows regulated air pressure to escape from the regulated pressure chamber (26) through the regulated pressure outlet (15), thereby reducing the regulated air pressure. Since all surfaces slide relative to one another, no components are subjected to extreme forces that can damage them during the process of reducing the regulated air pressure.

[0108] Finally, should the regulated pressure increase due to regulator creep, the increase in regulated pressure will push the piston (1) to the right. This movement will open the regulated pressure outlet (15) and release the excess pressure. The airgun will thus always be correctly pressurized and can be used from the very first shot.

[0109]

[0110] Figure 5 depicts the pressure regulator in its closed position. When a shot is fired, the pressure in the plenum (regulated pressure chamber (26)) will drop. When the pressurein the plenum drops, the disc spring stack (10) will overcome the pneumatic force applied by the regulated air on the piston (1) front face (16). The resultant imbalance of ferees will allow the disc spring stack (10) to push the piston (1) to the left. As the piston (1) is being pushed to the left, the inlet leaf spring face (2) will contact the angled face of the ridge (18) and the inlet leaf spring and seal (2) will be forced inward (refer Figure 6). When the inlet leaf spring and seal (2) is forced inward, the high-pressure inlet (14) will open, and high-pressure air will enter the plenum. Figure 6 shows the regulator in the open position. The piston (1) movement required to fully open the inlet leaf spring seal (2) is very small.

[0111]

[0112] When high pressure air enters the plenum, the increasing pneumatic force in the plenum will act on the piston front face (16) and push the piston (1) to the right. As the piston (1) is pushed to the right, the inlet leaf spring and seal (2) will be pushed outward by the spring tension in the inlet leaf spring and seal (3) and “ride” along the ridge (18). When the piston (1) reaches its initial position, spring tension in the inlet leaf spring and seal (2) will fully close the high-pressure inlet (14) and stop the flow of air.

[0113]

[0114] Dashpot chamber A (21) and dashpot chamber B (22) are joined by oil channel (23) and are filled with hydraulic fluid. As the piston (1 ) moves left under force from the disc springstack (10), the dashpot piston (1) (4) remains stationary, held in place by the adjustment screw (6), adjustment knob (12) and the interlocking screw (not numbered). Dashpot chamber A (21) will increase in volume and dashpot chamber B (22) will decrease in volume. Hydraulic fluid from dashpot chamber B (22) will be forced through the oil channel (23) into dashpot chamber A (21), providing effective oil damping to the piston (1) and thus eliminating any oscillations from the spring-mass system formed by the piston (1 ) and disc spring stack (10).

[0115] When the piston (1) moves to the right, the opposite takes place and effective damping is applied to the piston (1) during the closing action. Viscosity of the hydraulic fluid in dashpot chambers A and B (21 and 22) as well as the oil channel (23) dimensions have been designed to provide “critical” damping to the mass spring system formed by the piston (1) and the disc spring stack (10). Critical damping ensures that the piston (1) returns to its starting position in the shortest possible time without overshooting or undershooting yielding the best possible result.

[0116]

[0117] To increase the plenum pressure, the adjustment knob (12) is turned inwards. This will increase the force in the disc spring stack (10). This increase in force will be greater than the pneumatic force in the regulated air chamber (plenum) and the resultant imbalance of force will allow the piston (1) to move to the left. As the piston (1) is being pushed to the left, the inlet leaf spring and seal face (20) will contact the angled face of the ridge(18) and the inlet leaf spring and seal (2) will be forced inward. When the inlet leaf spring and seal (2) is forced inward, the high-pressure inlet (14) will open, and high-pressure air will enter the plenum increasing the pressure in the plenum. As pressure increases in the plenum, the pneumatic force on the piston (1) face (16) will increase, opposing the force in the disc spring stack (10). As the pressure in the plenum continues to rise, it will eventually overcome the force in the disc spring stack (10) and start pushing the piston (1) to the right. As the piston (1) is pushed to the right, the inlet leaf spring and seal (2) will be pushed outward by the spring tension in the inlet leaf spring and seal (3) and “ride” along the ridge (18). When the piston (1) reaches its initial position, spring tension in the inlet leaf spring and seal (2) will fully close the high-pressure inlet (14) and stop the flow of air. The result is higher pressure in the regulated air pressure chamber. Figure 6 shows the regulator with the inlet leaf spring and seal in the open position.

[0118]

[0119] To decrease the plenum pressure, the adjustment knob (12) is turned outward. This will decrease the force in the disc spring stack (10). The decrease in force will result in the pneumatic force acting on the piston (1) face (16) now being higher than that in the disc spring stack (10) and the piston (1) will be pushed to the right. As the piston (1) is being pushed to the right, the outlet leaf spring and seal bump (19) will contact the angled face on the ridge (18) and lift the outlet leaf spring and seal (3) from its seat. This action allows regulated air pressure to escape from the regulated pressure chamber (26) through the regulated pressure outlet (15). As air escapes the regulated pressure chamber (26)(plenum), the pneumatic force acting on the piston (1) face (16) will decrease. As the pneumatic force decreases, the force in the disc spring stack (10) will eventually overcome the pneumatic force and start pushing the piston (1) to the left. As the piston (1) is being pushed to the left, the outlet leaf spring and seal (3) will be pushed outward by the spring tension in the outlet leaf spring and seal (3) and “ride” along the angled face of the ridge (18). When the piston (1) reaches its initial position, the outlet leaf spring and seal will close the regulated pressure outlet (15) and stop the flow of air. The result is lower pressure in the regulated air pressure chamber. Figure 7 shows the regulator with the outlet leaf spring and seal (3) in the open position.

[0120] Notable features

[0121] The high-pressure air does not act on any part of the movable piston (1 ) responsible for opening and closing the high-pressure air inlet (14). All internal parts slide relative to each other, hence there is no sealing surface that can be damaged when adjusting the regulated pressure up or down. This allows the pressure regulator of the invention to be externally adjusted up or down over its full range of pressure regulation, which is ideal for the airgun enthusiast.

[0122] The addition of oil damping to the already existent hysteretic damping provided by the disc spring stack (10) allows precise control of the piston (1) position and hence repeatable and accurate opening and closing of the high-pressure inlet valve. Viscosity of the hydraulic fluid in dashpot chambers A and B (21 and 22) as well as the oil channel (23) dimensions have been designed to provide “critical” damping tothe mass spring system formed by the piston (1 ) and the disc spring stack (10). The expected result is that regulated air pressure will have a variation of a couple of millibars, which will be an order of magnitude better than current generation airgun regulators and airgun manufactures can do away with the practice of installing two or sometimes three regulators in a single gun.

[0123] The position of the inlet leaf spring and seal face (20) and outlet leaf spring and seal bump (19) with respect to the angled sides of the ridge (18) and the small piston (1) movement required to open and close them provides for very sensitive control of the regulator - small changes in regulated pressure will open either the high pressure inlet (14) or the regulated pressure outlet (15), precisely maintaining the regulated pressure at its set value.

[0124] Most current regulators suffer from “regulator creep” as indicated previously. Should this occur, the increase in regulated pressure will push the piston (1) to the right. This movement will open the regulated pressure outlet (15) and release the excess pressure. The airgun will thus always be correctly pressurized and can be used from the very first shot.

[0125] Should there be an increase in the regulated pressure chamber (26) due to an increase in the ambient temperature, the leaf regulator will release this excess pressure in the same way as for “regulator creep”.

[0126] It is not possible to overpressure the regulated pressure chamber (26). As the regulated pressure is controlled by compression in the disc spring stack (10), increasing compression in the disc spring stack (10) will lead to higher pressures. The leaf regulator prevents overpressure by:o Limiting movement of the adjustment knob with a hard stop, i.e. , the disc spring stack (10) cannot be compressed further than that allowed by design; and o Should overpressure occur, the piston (1) will move right and open the regulated pressure outlet (15) and release the excess pressure.

[0127] Many airgun enthusiasts in the search for more power or shooting heavier projectiles, increase the pressure in the regulated pressure chamber (26) to beyond that recommended by the manufacturer. To use higher pressures, the disc spring stack must be compressed beyond its elastic limit which will damage the individual disc springs in the stack. Further, regulators tend to be small and the disc springs available in such small sizes cannot accommodate the high pressures demanded by the users. The net effect is that current regulators are limited by physical size to maximum regulated air pressures between 160 to 180 bars depending on the design. The pressure regulator overcomes this problem, by introducing a rear piston (1 ) face (17), exposed to the regulated air pressure through four coaxial channels (not shown). The rear piston (1) face (17) reduces the total frontal face (16) area and hence the pneumatic force required to oppose the force in the disc spring stack (10) for a given pressure setting. In doing so, the maximum regulated air pressure can be increased without damaging the disc spring stack (10) while maintaining a compact size. This effectively extends the working pressure range of the regulator.Advantages

[0128] • Precise regulated pressure control with predicted fluctuations in the millibar range from shot to shot

[0129] • Externally adjustable regulated pressure up, regulated pressure down

[0130] • Extended regulated pressure working range

[0131] • Eliminate regulator creep and over pressure issues

[0132] • Does not need a second regulator for precise regulated pressure control

[0133] • Self-adjust to changes in the ambient temperature

[0134] It will be appreciated that alternative embodiments of the invention are possible without departing from the spirit or scope of the invention as defined in the claims.

Claims

1. CLAIMS1. A pressure regulator suitable for use on a pre-charged pneumatic airgun wherein the pressure regulator is arranged between a plenum and a source of compressed gas, the pressure regulator comprising - a tubular housing (7) including - a regulated pressure chamber (26) that is arranged in air flow communication with the plenum, anda high-pressure inlet (14) extending through a housing (7) wall into the regulated pressure chamber (26) for directing ingress of high-pressure air from the source of compressed gas into the regulated pressure chamber (26); a tubular regulator piston (1) coaxially mounted, and slidingly displaceable, within the housing (7) between a first axial direction and an opposite second axial direction;biasing means (10) for biasing the regulator piston (1) resiliently in the first axial direction;a first sealing member (2) being arranged within the regulated pressure chamber (26) for alternately opening and closing the high-pressure inlet (14) against the housing (7) wall, the first sealing member (2) being positioned radially between the regulator piston (1) and the housing (7) wall and being actuated between an open and closed position through displacement of the regulator piston (1);wherein the regulator piston (1) is displaceable in the first axial direction in the same direction as the biasing force of the biasing means (10) under influence ofa pressure decrease in the regulated pressure chamber (26), and wherein such regulator piston (1) displacement in the first direction actuates the first sealing member (2) to open the high-pressure inlet (14) to allow ingress of pressurised gas from the source of compressed gas into the regulated pressure chamber (26); and wherein such increased pressure from the high-pressure inlet (14) acts upon the regulator piston (1) to exert a pneumatic force on the regulator piston (1) in an opposite direction as the biasing force of the biasing means (10) to displace the regulator piston (1) against the biasing force of the biasing means (10) in a second opposite direction; and wherein such regulator piston (1 ) displacement in the second direction actuates the first sealing member (2) to close the high-pressure inlet (14), andwherein airflow into the regulated pressure chamber (26) is controlled perpendicularly to the axial displacement of the regulator piston (1).

2. The pressure regulator according to claim 1 wherein the first sealing member (2) is radially displaceable relative to the regulator piston (1).

3. The pressure regulator according to claim 2 wherein displacement of the regulator piston (1) in the first axial direction radially displaces the first sealing member (2) to open the high-pressure inlet (14), while displacement of the regulator piston (1) in the second axial direction radially displaces the first sealing member (2) to close the high-pressure inlet (14).

4. The pressure regulator according to claim 3 wherein the first sealing member (2) is angularly displaceable relative to the axial displacement direction of the regulator piston (1).

5. The pressure regulator according to claim 3 wherein the pressure regulator further comprises - a regulated pressure outlet (15) for directing egress of high-pressure air from the regulated pressure chamber (26) to atmosphere through the housing (7); and a second sealing member (3) for alternately opening and closing the regulated pressure outlet (15) and which is actuated between an open and closed position through movement of the regulator piston (1).

6. The pressure regulator according to claim 5 wherein the second sealing member (3) is arranged within the regulated pressure chamber, positioned radially between the regulator piston (1) and the housing (7) wall.

7. The pressure regulator according to claim 6 wherein the second sealing member (3) is either radially displaceable relative to the regulator piston (1); or the second sealing member (3) is angularly displaceable relative to the axial displacement direction of the regulator piston (1).

8. The pressure regulator according to claim 7 wherein the housing (7) includes a guiding ridge (18) extending radially inwardly from the housing (7) wall into theregulated pressure chamber (26) and positioned for guiding the first and second sealing members (2; 3) between the open and closed positions through movement of the regulator piston (1).

9. The pressure regulator according to claim 8 wherein the guiding ridge (18) includes a first angularly disposed guiding face that cooperates with the first sealing member (2); and a second, oppositely angularly disposed guiding face that cooperates with the second sealing member (3).

10. The pressure regulator according to claim 9 wherein the first angled guiding face of the guiding ridge (18) guides the first sealing member (2) to open the high-pressure inlet (14) when the regulator piston (1) is displaced in the first direction, and guides the first sealing member (2) to close the high-pressure inlet (14) when the regulator piston (1) is displaced in the second, opposite direction; while the second angled guiding face of the guiding ridge (18) guides the second sealing member (3) to open the regulated pressure outlet (15) when the regulator piston (1) is displaced in the second direction, and guides the second sealing member (3) to close the regulated pressure outlet (15) when the regulator piston (1) is displaced in the first direction.

11. The pressure regulator according to claim 10 wherein the pressure regulator includes an open-ended tubular housing cap (8) which is removably insertable into an open end of the tubular housing (7), and which defines the guiding ridge (18),such that displacement of the regulator piston (1) in the first direction is limited by the housing cap (8).

12. The pressure regulator according to claim 11 wherein the housing (7) includes a locating groove (26) extending coaxially with the regulator piston (1) within an interior wall of the housing (7) and configured for receiving a complimentarily configured piston guide (24) extending radially outwardly from the regulator piston (1 ) for axially guiding the regulator piston (1 ) in the first and second directions within the housing (7), but preventing rotation of the regulator piston (1) within the housing (7) to ensure consistently accurate location of the piston relative to the high-pressure inlet (14) and the regulated pressure outlet (15).

13. The pressure regulator according to claim 12 wherein both the first and second sealing members (2; 3) are leaf springs.

14. The pressure regulator according to claim 13 wherein the biasing means (10) is a disc spring stack.

15. The pressure regulator according to claim 14 wherein the pressure regulator is externally adjustable and includes a rotatable adjustment screw (6) for externally increasing pressure in the regulated pressure chamber (26) by rotating the adjustment screw (6) in a first direction, and externally decreasing pressure in theregulated pressure chamber (26) by rotating the adjustment screw (6) in a second opposite direction.

16. The pressure regulator according to claim 15 wherein the adjustment screw (6) is coaxially aligned with and seated against the disc spring stack (10).

17. The pressure regulator according to claim 15 wherein the adjustment screw (6) is perpendicularly orientated relative to the disc spring stack (10) and cooperates with an angled nut (28) which moves up and down when the perpendicular adjustment screw (6) is turned in or out, the arrangement being such that by turning the perpendicular screw (6) in or out, the angled nut (28) acts on an adjustment piston (27) with a corresponding angle through an angled surface (30), increasing or decreasing the biasing force in the disc spring stack (10).

18. The pressure regulator according to anyone of claims 15 to 17 wherein pressure in the regulated pressure chamber (26) is increased by rotating the adjustment screw (6) in a first direction, thereby increasing the biasing force in the disc spring stack (10) to a force which is greater than the opposing pneumatic force in the regulated pressure chamber, thus forcing the regulator piston (1) in the first direction, which in turn actuates the first sealing member (2) against the guiding ridge (18) to the open position to allow ingress of high-pressure gas through the high-pressure inlet (14) into the regulated pressure chamber (26), so that as pressure increases in the regulated pressure chamber (26), the pneumatic force acting on the regulator piston(1) increases, opposing and eventually overcoming the biasing force in the disc spring stack (10), thus pushing the regulator piston (1) in the second opposite direction, which in turn actuates the first sealing member (2) against the guiding ridge (18) to the closed position to block ingress of high-pressure gas into the secondary chamber, resulting in higher pressure in the regulated pressure chamber (26).

19. The pressure regulator according to anyone of claims 15 to 17 wherein pressure in the regulated pressure chamber (26) is decreased by rotating the adjustment screw (6) in a second, opposite direction, thereby decreasing the biasing force in the disc spring stack (10) to a force which is less than the opposing pneumatic force in the regulated pressure chamber, thus forcing the regulator piston (1) in the second direction which in turn actuates the second sealing member (3) against the guiding ridge (18) to the open position, allowing regulated air pressure to escape from the regulated pressure chamber (26) through the regulated pressure outlet (15), so that as air escapes from the regulated pressure chamber (26), the pneumatic force acting on the regulator piston (1) decreases to a point where the force in the disc spring stack (10) eventually overcomes the pneumatic force, thus pushing the regulator piston (1) in the first direction, while the second sealing member (3) is actuated against the guiding ridge (18) to the closed position to close the regulated pressure outlet (15) and stop the flow of air, resulting in lower pressure in the regulated pressure chamber.

20. The pressure regulator according to anyone of claims 15 to 17 wherein the pressure regulator further includes an active hydraulic damping system adapted for reducing regulator piston (1) oscillations, the damping system being coaxially aligned with the regulator piston (1) and comprising - a dashpot chamber A (21) and a dashpot chamber B (22), both filled with hydraulic fluid,an oil channel (23) for fluidly connecting dashpot chambersAand B (21 ; 22); anda stationary dashpot piston which is secured to the adjustment screw (6), and which separates dashpot chambers A and B,the arrangement being such that displacement of the regulator piston (1) in the first direction under the biasing force from the disc spring stack (10) increases volume in dashpot chamber A (21) and decreases volume in dashpot chamber B (22), forcing hydraulic fluid from dashpot chamber B (22) through the oil channel (23) into dashpot chamber A (21), while displacement of the regulator piston (1) in the second direction under the pneumatic force of the high-pressure inlet (14) decreases volume in dashpot chamber A (21) and increases volume in dashpot chamber B (22), forcing hydraulic fluid from dashpot chamber A (21) through the oil channel (23) into dashpot chamber B (22), thereby providing effective oil damping to the regulator piston (1) and thus reducing piston oscillations.

21. The pressure regulator according to claim 20 wherein the regulator piston (1) includes a radially outwardly extending piston flange (27) that slidingly engages aninterior of the housing (7) wall and that defines a piston front face (16) which is orientated towards, and exposed to regulated pressure from, the regulated pressure chamber; and an opposite piston rear face (17) which is orientated towards the disc spring stack (10) and exposed to regulated pressure by means of at least one, but preferably a number of, air channels (25) extending coaxially through the piston flange (27), the arrangement being such that pressurised air flow from the regulated pressure chamber (26) through the air channels (25) exposes the piston rear face (17) to regulated air pressure which reduces the pneumatic force required to oppose the biasing force in the disc spring stack (10).

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