The invention relates to a device which exhibits a moisture response, in particular to change between a first state and a second state mechanically to perform an operation, for example to serve as a moisture operated valve, switch, sensor, actuator or the like, and to a method of use.

In one embodiment the invention relates to a valve device and method for regulating the outflow of fluid from a hose or conduit supply into a receiving reservoir, tank, trough, tray, channel, receptacle, and also onto and into the ground or a growing medium at the outflow ends of an irrigation hose distribution system, for example in farming. In another embodiment the invention relates to a sensing or switching device capable of providing a signal means in response to a change in moisture level, for example as a part of a flood alarm system and in a further embodiment the invention relates to an actuator means where one or a number of the devices may be employed to generate a pilot operative change of condition, in a hydraulic and/ or pneumatic system to initiate by hydraulic and/ or pneumatic means a sequence capable of closing off and/ or opening a significant fluid conduit.

The invention, and the prior art, are largely discussed in these preferred contexts but the more general applicability of the invention will be understood.

In the case of hose-fed agricultural irrigation the overall benefits of current Dripper Irrigation systems (i.e. where the Dripper valves employed do not possess moisture-activation properties) tail off significantly when the number of Dripper valve water outflows are reduced from many thousands to a lesser number and/ or where it is necessary to water mixed species and/ or ages of trees, shrubs and vines with wide-ranging watering requirements from a common hose-fed distribution system i.e. when conventionally all the Dripper valve outlets have a standard rate of outflow. The general principle of how a Dripper valve works is revealed in patent US 3,604,728 Blass, et al. 1969, where a pressurised hose distribution system may preferably include a number of spaced apart specialised fluid outlet valves and where each valve incorporates a micro-scale labyrinthine fluid pathway to cause a pressure drop and deliberately attenuate the natural rate of outflow of fluid to a preferred lower value in common with all of the valves present in the system, to achieve the uniform watering of uniform crops. The micro-scale, labyrinthine water paths dictate that these pressurised systems will only operate successfully for any length of time, when clean filtered water is employed, which in many regions of the world is neither available nor necessary for the irrigation of crops. When clean water is used these systems still need regular maintenance and cleaning due to biological growths and chemical agglomerations and sediment deposits which accumulate inside the hoses and dripper valves.

There are also known Prior Art moisture-activated watering devices such as; patents; US 4,121 ,608 MacLeod 1977, US 4,182,357 Ornstein 1978, US 4,214,701 Beckmann 1978, US 5,382,270 Graham, et al. 1995 and US 5,794,848 Nunn, et al. 1994, which when employed in conjunction with a continuous supply of irrigation fluid exhibit drawbacks and are generally biased towards cycling narrowly between some partially-open state and their closed-off state. Crucially for these valves even minor in-line debris has been observed to accumulate and cause a fluid flow restriction, detrimental to the plant or plants being watered. Many of the drawbacks are similar to those outlined for dripper valves. When used in conjunction with irrigation timers set to switch on and off periodically, i.e., where water may be switched-on for perhaps only one hour in every twenty-four hours, the slow incremental re-opening of these prior art valves, i.e. moisture-activated watering devices, from their tightly- closed positions may so overlap the timer cycle that a plant in need of water misses out on a watering opportunity. This is exacerbated when inline debris accumulates to partially clog up the nip zone inside these valves.

Whether supplied from a continuous head of water or timed to receive water periodically the motion of these earlier moisture-activated watering devices is often virtually imperceptible to the human eye and very sluggish. Given a free-choice a designer skilled in the art would not select this type of motion for a moisture-activated, water irrigation valve. A preferred motion would have a snappier action and more closely resemble the positive opening and closing of an electrical bi-metal micro-switch. One way of achieving this is demonstrated in my earlier published International Patent Application WO 2008/068496 A1. This reveals that conventional pressurised hose-fed irrigation systems may be replaced with low-head, gravity hose-fed water supplies of a half to two metre water head, and that the multitude of conventional dripper valve outlets, so dependant on a high working pressure, may then be replaced with moisture-activated polymer valves which all open independently, to fully satisfy the individual requirements of each, for example, tree, shrub or vine, and also freely purge out any accumulations.

However, some of these same drawbacks also exist in relation to moisture responsive devices which, rather than being directly actuatable valves, would be designed to constitute moisture actuated sensors and/or switches, for example electronic sensors and/or switches, based on similar principles, where the fundamental underlying moisture response is effected by relative distortion of a hydroscopic or otherwise moisture absorbent material. Thus, although the invention is discussed primarily in the context of devices where such a distortion produces a direct mechanical "valve" effect, it will be understood that the same principles could be applied for example where the mechanical distortion is employed indirectly to produce a sensor detection or switching effect, and in particular to generate and/ or modify an electrical sensor signal and/or actuate an electrical switch.

Further the invention can be incorporated into a hydraulic and/ or pneumatic circuit to function directly as a pilot actuator providing a useful fluid force or pulse within a larger hydraulic and/ or pneumatic arrangement which would be capable of switching, for example a pressurised municipal water supply off, and even back on again without any requirement for electrical energy.

In accordance with the invention in a first aspect there is provided moisture responsive device having: a generally domed or raised three dimensional moisture responsive structure comprising at least a moisture responsive formation of a first material in association with a less moisture responsive formation of a second material, in that the first material has a greater tendency to absorb moisture, and to increase in volume as a result, than the second material, the two formations being so arranged together with the first material outermost on a hollow or three dimensional inner surface, that such differential change in volume tends to cause mechanical deformation of the moisture responsive structure to change in formation from a generally domed or three dimensional state to a generally opposite domed or three dimensional state so that the first material is outermost on a domed or three dimensional outer surface of the moisture responsive structure; and a flexibly elongate actuation member of flexibly resilient material situated in close mechanical association with the second material of the moisture responsive structure, so that deformation of the moisture responsive structure in the presence of moisture, tends to change the shape of the actuation member and thereby cause the actuation member to change between at least a first functional state and a second functional state.

The new invention exhibits at least four advantages over the previous invention described in earlier published International Patent Application WO 2008/068496 by way of its significantly different geometry and mode of operation:

In the first of these there is the potential for reducing the time taken to wet- up and to dry out, as the same quantity of moisture responsive material in the moisture responsive structure can be distributed in a different way, i.e. the invention provides for a greatly increased exposed surface area by way of a circular disk-like formation and more generously in three dimensions. By employing in one arrangement a thin-walled hollow, shallow spherical sector or the like, including a saddle-shape plane conforming to a hyperbolic paraboloid, and in a second arrangement a thin-walled shallow formation of generally truncated cone appearance of plain or radially corrugated or scalloped surface.

It is therefore possible to reduce the thickness of the moisture responsive material and so make the invention respond faster. This is a preferred property for use in quick response devices such as in the case of a flood alarm. My earlier invention made use of the properties of a generally elongate, flat moisture responsive structure with a limited surface area or footprint, and therefore was constrained towards having a relatively thick material cross-section to generate forces large enough to initiate the collapse of the actuation member - to form a kink closure. In a number of applications thin material cross-sections are more desirable in order to improve the response of the device. With the limitation on the earlier footprint the distorting forces could only become greater in magnitude by increasing the material thickness, as a consequence the device took a significantly longer time to wet-up and subsequently dry out again.

Secondly, in this new invention the more complex three dimensional geometry is designed to exploit the novel combination of at least two distinct shape-changing effects (which effects are reversible when experienced within the elastic limits of each of the materials) originating from within (i) the concave or recessed three dimensional moisture responsive structure and (ii) the resilient actuator tube member, for example as the moisture responsive structure absorbs moisture and develops internal forces, sufficient eventually, to self-invert its geometrical shape, by the action of moisture alone, the act of inversion triggers the collapse of the actuator tube member to form a kink. My earlier invention had a simple elongate moisture responsive structure which when dry was generally flat and aligned along the axis of the actuation member. In the presence of moisture the moisture responsive structure extended and also curled over time to form a pronounced arc and subsequent drying out exhibited the reverse of this process. The snap action "effect" sought after did not originate in the moisture responsive structure. The "effect" was created by the actuation tube member itself as it yielded to the pincer action created by the developing arc formation of the moisture responsive structure, the actuation tube member collapsed upon its self and a kink closure was formed. Thirdly, in this new invention the life expectancy of the device is considerably increased by the different mode of operation, for example incorporated into a hose-fed irrigation system, the device will need to remain in a collapsed closed-off state for most of the time, which condition may cause eventual permanent distortion or "set" in one or all of the materials. Beneficially as the moisture responsive structure changes its attitude from a dry relaxed state to a wetted invert state, it experiences a maximum expansive stress as it progresses through an unstable most flattened out state, before coming to rest in an opposite state of rest where the expansive forces are considerably diminished. As a consequence the device can remain in the collapsed closed-off state for considerably longer periods without loss of mechanical response. In my earlier invention the moisture responsive elongate member curled to form a pronounced arc, i.e. in a condition of activation and maximum stress, which arc and stress prevailed for as long as the device was wetted and in a closed-off state.

Fourthly, there is the potential to incorporate a delay effect into the resilient connections provided by the two or more 'stand-offs' or webs located between the moisture responsive structure and the actuation member, by way of flexible linkages or pivots selectively incorporated to influence the mechanical behaviour of the invention as the moisture responsive structure progresses from one state of equilibrium to its inverse state of equilibrium.

By introducing a degree of slackness, play or delay into the region of the stand-offs. There is a benefit to be gained, especially when the device dries out to reopen the actuator tube, which may have experienced a closed-off state for an extended period of time, which time has the potential to induce an undesirable permanent distortion in the polymeric material of the actuator tube. This is because it allows the motion of the geometrical inversion to become well advanced, and thus provide free space for the actuator tube to resiliency reopen, from its compressed condition, of its own accord, before facilitating this motion further by imposing a direct mechanical action as the two main parts of the device are realigned to their original configuration, i.e. in a dry state of rest and where the actuator tube may preferentially experience a minimal longitudinal tension, inherent in the design and manufacture of the device.

These new features were absent from the earlier invention described in published International Patent Application WO 2008/068496.

The present invention thus provides a moisture responsive device, and a method of use of the same, in which are mitigated at least some of the disadvantages of at least some of the prior art systems described earlier, and are included one or more of the advantages described hereinabove.

In a particularly preferred case the present invention provides a moisture responsive device, and a method of use of the same exploiting at least one beneficial combination of mechanical perturbations of a moisture responsive means which exhibits improved response to changing moisture levels both in its opening period and in its closing period, and where the precise nature of the opening and closing actions can be independently engineered to achieve a preferred operational performance for a particular application.

In a particularly preferred case the invention provides an irrigation control device and method of employing the device, which involves fewer complex moving parts and a reduced chance of mechanical fouling and failure in use. As described, in accordance with the invention in a first aspect there is provided a moisture responsive device having a generally donned or raised three dimensional moisture responsive structure. The moisture responsive structure is generally domed or raised in a convenient case in that it comprises a sheet-like structure extending in two dimensions and shaped such that in a first state being in use a relatively dry state, and for example constituting an at-rest or undistorted state, the structure projects out of the notional plane of the sheet to form a domed or like structure. For example, the perimeter of the sheet-like structure lies in a plane and the sheet-like structure projects out of that plane in an at-rest undistorted state to define a domed or raised configuration. This defines an inner or concave surface and an outer or convex surface.

The moisture responsive structure comprises at least a moisture responsive formation of a first material in association with a less moisture responsive formation of a second material, for example forming a sheet- like combination. The relative moisture responsiveness is defined in that the first material has a greater tendency to absorb moisture, and to increase in volume as a result, than the second material, which may conveniently be flexibly resilient

The two formations are so mechanically arranged together and for example intimately connected together with the first material outermost on a hollow or concave inner surface of the three dimensional structure that such differential change in volume tends to cause mechanical deformation of the moisture responsive structure to cause it to change in formation from a generally domed or raised first state as above described to a generally opposite domed or raised second state in which opposite state the first material is outermost on a domed or convex three dimensional outer surface of the three dimensional moisture responsive structure. Most preferably, the moisture responsive structure is so configured that said differential change in volume tends to cause mechanical deformation of the moisture responsive structure to invert the geometric orientation of the moisture responsive structure. The second state corresponds to a state following exposure to moisture, hence being a relatively wetted state.

It has been found that with proper design of the moisture responsive structure such a response can be engineered to be particularly decisive, for example when compared with the response of a linear strip as described in WO 2008/068496. In effect, the moisture responsive structure can be made to flip between a pair of bistable states. This potentially more decisive response is the basis of many of the advantages of the device set out herein.

In a broadest aspect, the device is completed by provision of a flexibly elongate actuation member of flexibly resilient material situated in close mechanical association with the second material of the moisture responsive structure, so that deformation of the moisture responsive structure in the presence of moisture tends to change the shape of the actuation member and thereby cause the actuation member to change between at least a first functional state and a second functional state. For example, deformation of the moisture responsive structure in the presence of moisture tends to invert the geometric orientation of the moisture responsive structure and also change the shape of the actuation member and thereby cause the actuation member to change between at least a first functional state of rest and a second functional state of rest, and where the maximum material stresses generated by the deformation process are partially diminished. The invention thus lies in the very simple combination of a moisture responsive structure which deforms inherently as moisture levels vary and is capable when in contact, for a period of time with moisture, of inverting its geometry, and a flexibly resilient actuation member which is mechanically coupled to this structure in such a manner that this deformation tends in use to mechanically distort the actuation member, and for example to introduce directional changes such as bends or kinks into the actuation member. The flexibly elongate actuation member is so configured that this distortion of the actuation member is such as to initiate a desired effect either directly within the actuation member or by effecting transmission of a signal from the actuation member. In particular, the actuation member thus effects a change between at least a first and at least second state, which change may be either analogue and progressive or digital and discontinuous, as the moisture responsive structure deforms. The change is revertable as the deformation of the moisture responsive structure reverts to its initial state with changed moisture levels. In this way, the device of the invention acts as a moisture operated switching means in the general sense, in that a detectable and optionally directly functional state change is induced in an actuation member as the moisture conditions change.

In a particularly preferred application, the switching action provided by the combination of the geometrical inversion of the moisture responsive structure and the distortion of the actuation member is intended to operate as a moisture-actuated closure for a fluid conduit system, and for example, an automatic moisture-actuated closure for an irrigation system. The device preferably includes an operable closure formation, actuatable by and for example including or constituted as a part of the actuation member. That is to say, the device is so configured that a culminating functional change in an actuation member effects selective operation (i.e. selective opening and closing in a moisture responsive manner) of the operable closure formation and in a preferred embodiment, the actuation member is or constitutes at least a part of the operable closure formation so that the functional change directly effects at least in part, operation of the operable closure formation.

The device of the invention lends itself particularly to this mode of operation, in accordance with a preferred embodiment, wherein the flexibly resilient elongate actuation member is a conduit member serving as a portion of a fluid transfer conduit which is directly deformable as the moisture responsive structure deforms to introduce directional changes such as bends or kinks in the flexibly resilient conduit, and to tend to occlude a fluid channel within the conduit and so inhibit fluid flow therealong. Thus, the actuation member itself constitutes a closure formation. Subsequent discussion of embodiments of the invention will focus on a limited number of such examples.

However, it will be understood that the principles of the invention can be applied to any switching system whereby it is desired to produce a reversible state change from one state to another in the actuation member as the moisture level changes at the device and effects deformation of the moisture responsive structure. For example, an application can be envisaged as an electrical moisture sensor or moisture actuated switch wherein the flexibly elongate actuation member includes within it and in place of a fluid, a conductor or conductors, piezoelectric material, or any like functionality so as to generate or modify an electrical signal and/or change conditions in an electronic circuit of which the device forms a part as the element deforms. In this type of assembly the flexibly elongate actuation member might be made with a different hollow cross-section such as lozenge shaped, to provide more internal space, and also be sealed at each end to reliably house, for example, electronic circuits, a battery power source, RFID circuitry and wireless means to exchange data with an external transceiver means. Thus, the principles of the invention can be applied to any system of moisture sensor or moisture activated switch where a mechanical distortion of the elongate functional member can effect actuation of the sensor or switch.

In accordance with the invention in a preferred embodiment there is provided a device for regulation of irrigation fluid comprising a domed or three-dimensional moisture responsive structure comprising at least a moisture responsive formation of a first moisture responsive material constituting some or all of the outermost material on the inside hollow surface of a domed or three dimensional structure in direct mechanical association with a less moisture responsive formation of a second less moisture responsive and for example relatively unresponsive and/or hydrophobic material which is flexibly resilient and on the outermost, outward facing surface of a domed or three dimensional structure, in that the first material has a greater tendency to absorb moisture and to increase in volume as a result than the second material, the two formations being so mechanically arranged together that such differential change in volume tends to cause mechanical deformation giving rise to geometrical inversion of the moisture responsive structure; and a fluid conduit of flexibly resilient material in such mechanical association with the moisture responsive structure that the combined effect of the geometrical inversion of the moisture responsive structure in the presence of moisture and the distortion of the actuation member tends to mechanically distort the fluid conduit to introduce one or more kinks therein and thus to inhibit fluid flow. Again, the invention thus lies in the very simple combination of a moisture responsive structure which deforms inherently as moisture levels vary and is capable when in contact with moisture of inverting its geometry, and a flexibly resilient conduit, such as an elongate tube or the like, which is mechanically coupled to this structure in such a manner that this distortion tends in use to introduce directional changes such as bends or kinks into the conduit. By virtue of the nature of the conduit, such directional changes are likely to constitute flow restrictions in a conduit bore, and to tend to inhibit the passage of fluid through the conduit bore.

For example, in a most usual mode of operation of this embodiment, a conduit, preferably in the form of a flexibly resilient tubular member, with a tube bore acting as a passage for irrigation fluid in use, will be so constructed that the conduit member lies generally straight in a generally dry and open-bore state, in a tangential alignment crosswise, over the outside top surface of the domed or raised three dimensional structure, but is caused to become kinked, resulting in at least partial closure of the bore, under the mechanical action of the moisture responsive structure as the more moisture absorbent first material swells.

The invention is therefore very mechanically simple, with essentially no moving parts. It responds to the environmental moisture levels, tending to effect actuation of the actuation member and in the preferred embodiment close the fluid conduit and for example the tube bore and prevent further watering, on the basis of the automatic response created by mechanical deformation and geometrical inversion of the moisture responsive structure. This is effected in an admirably simple manner, by exploiting the differential physical absorption properties of the two materials, and in particular selecting those two materials such that the first material tends to absorb moisture and increase in volume in a wetter state to a greater extent than the second material.

The materials expand differentially as moisture levels change. For example one material expands as it absorbs moisture, and the other material exhibits relatively little expansion. For example, the first material is a relatively hygroscopic material, and the second material is a relatively less hygroscopic material, and is for example a relatively hydrophobic material. The relatively in-expansive second material is conveniently resiliency deformable to deform as the first material expands and reverts to its original configuration as the first material contracts, so that the moisture responsive structure deforms reversibly without excessive build up of stresses between the two materials and prolongs device lifetime. The first material is conveniently also resiliently deformable. For example, a resiliently deformable material is an elastomeric polymer.

The two materials are mechanically arranged together that such differential swelling of the two formations tends to cause mechanical deformation, i.e. extension, of the moisture responsive structure. In particular the two materials are intimately preferably connected together. In particular they are mechanically engaged together, for example directly by a shared bonded surface. The shared surface may be bonded adhesively, thermally or mechanically, but is preferably bonded in that at least one of the materials is laid down on the other via a melt forming process. For example at least one of the materials is laid down on the other using a twin shot moulding sequence e.g. over-moulded. This gives an intimate contact better able to resist the forces generated as the two formations are differentially distorted in use. Whilst the invention is described in its simplest in terms of two materials with differential properties to make up the moisture responsive structure, the invention is not so limited, and any number of materials may be used provided there is at least a moisture responsive formation of a first material with relatively high moisture absorption and exhibiting a relatively high volume change relative to a less moisture responsive formation (for example a substantially moisture invariant formation) of second material with relatively lower moisture absorption and thus exhibiting a relatively lower volume change with which it is so mechanically engaged that the element undergoes a shape change deformation between a relative dry and a relatively wetted state, and that in the extreme this deformation gives rise to a geometrical inversion such as to distort a flexibly resilient actuation member such as a fluid conduit, which may be of the same second material or comprised of a third material, in mechanical association with the moisture responsive structure in such manner as to tend to actuate the actuation member and for example close a conduit passage to the through transfer of irrigation fluid.

In a particularly convenient embodiment, the moisture responsive bi- polymer formation has a domed or three dimensional structure of generally thin material cross-section that is either continuous or web-like, with the first and second materials being so arranged that it tends to distort, preferably between a generally domed or raised three dimensional state of rest, and a generally inverted or recessed three dimensional state of the same, experiencing during the inversion process, in either direction, a transitory unstable state of maximum distortion and stress midway between the bi-stable states of rest. In particular, the structure is configured such that it adopts a generally domed or three dimensional state of rest in an un-wetted state, and tends to invert to an opposite formation when it is wetted. This is conveniently achieved in that the first material and the second material are essentially disposed alongside one another and bonded directly together, in a domed or three dimensional formation with the first material outermost on the inside hollow surface of the domed or three dimensional structure, such that the increased tendency of the first material to absorb moisture and increase in volume i.e. become swollen, will distort and expand the structure and tend to leave the first material, in the distorted and expanded wetted state, on the outermost, outer surface of a domed or three dimensional structure, and the second material, which material can preferably be elastically-stretched in the process by the action of the first material, outermost on the inner hollow surface of a domed or three dimensional structure which will be somewhat enlarged from the swelling action and in an opposite state of rest or equilibrium.

This arrangement lends itself to ensuring that an actuation member, for example a flexibly resilient fluid conduit such as a tubular member, may be advantageously mechanically engaged upon but laterally distanced in a generally tangential alignment crosswise over the outer top surface of the domed or three dimensional surface by lateral engaging projections or stand-offs. Preferably, at least a pair of such projections or stand-offs is provided. This arrangement not only projects the actuation member such as the flexibly resilient tubular member to such a point where, as the structure tends to its inverted state the process generates the necessary forces in the actuation member to create the desired deformation, and for example a kink, but also, where at least a pair of such projections or stand-offs is provided, tends to provide a mechanical system where a controlled deformation such as a kink in the flexibly resilient tubular member is much more reliably generated, generally at the mid point between the pair or pairs of projections. Said projections are preferably short and may be varied in height, in order to achieve the desired physical clearances within the device and kinking effect for a particular application.

In a preferred embodiment, the moisture responsive structure comprises at least a bi-layer in which at least a first layer or web of the said first material is mechanically associated with at least a second layer or web of said second material. Conveniently, such a bi-layer is formed by an over- moulding or twin-shot moulding process. Alternatively the first and second materials may be manufactured separately for example by injection moulding, compression moulding, slip moulding or stretch or vacuum forming and bonded together using an adhesive or other joining methodology, or fabricated or manufactured via any other suitable process. Preferably, the forming process additionally co-forms the actuation member such as the conduit with the moisture responsive element. When necessary, perforations, apertures and or raised bumps, rims and or ribs to improve air flow and mechanical properties in the final device may be incorporated at a preferred stage in the process in accordance with the invention.

In a preferred embodiment of the invention a tubular conduit is included as an irrigation control device in a practical irrigation system, whether indoors or outdoors, and whether for domestic gardening or commercial horticulture or agriculture, can be readily understood. The simple device of the invention is adapted to distort in the presence of moisture to a point where, once a certain degree of distortion is reached there is a further more observable distortion of the moisture responsive structure as it geometrically inverts, enabling a control signal to be generated by the subsequent consequential distortion of the tubular conduit to control irrigation. In effect, the actuation member generates a switching effect to switch an irrigation flow on and off. This may be indirect, in that the actuation member generates a moisture sensor signal which is used by control means to control irrigation, or direct in that the actuation member serves as part of a mechanical, electromechanical, or electrical valve or valve switch arrangement that closes as moisture levels rise. In the preferred embodiment, the actuation member is a fluid conduit that is so distorted as to inhibit fluid flow within the conduit. The conduit is therefore in itself in effect a valve means that actuates automatically as moisture levels change. Alternatively, switcher actuators, such as wire connectors, may be disposed within the conduit and or the tubular conduit may be incorporated into a hydraulic and or pneumatic system to directly or indirectly open and close a fluid circuit or initiate a change for example by the generation of a useful pressure wave or pulse, via additional apparatus, engaged with and performing the actuation of a very much larger capacity fluid conduit for example piped water supplied under pressure from a municipal water supply.

Clearly, such a device can serve in practice as a moisture responsive valve means within an irrigation system, with a device in accordance with the invention fitted in an irrigation fluid distribution line, typically in the vicinity of a site where irrigation fluid is to be delivered, and thus respond to in situ conditions and selectively allow or inhibit further watering.

The device or multiples thereof may be employed in a first application when plants, vines, shrubs, trees and the like are irrigated on mass via a distribution network of irrigation hoses fed ultimately from a source of either constant head or fixed-volume irrigation fluid. In a second application the device or multiples thereof may be employed in conjunction with a timer based irrigation fluid system which is set to initiate either a time-based or volume-based periodic outflow from a source of irrigation fluid. In either instance, the simple valve in accordance with the invention should prevent over-watering by detecting in situ when moisture levels are relatively high (in that the moisture responsive element will then be distorted) and acting in effect as a valve closure in such circumstances (in that the distortion of the element will introduce the necessary distortion of the conduit to cause partial or complete closure thereof, and inhibit further irrigation fluid flow). The valve mechanism is dynamically responsive, and fully reversible. The absence of mechanical moving parts improves reliability and lifetime. Further, the "valve" is entirely closed to the environment, in that it merely comprises a reversible distortion in the tubular member or other conduit, and so there is no tendency to environmental fouling of the "valve" mechanism.

Similarly the same device perhaps envisaged on a larger scale might be employed close-to or at the out-flowing end of a low pressure, high volume fluid supply pipe or conduit tube used to fill header tanks or the like which in turn may be used to supply gravity-fed water to irrigation systems or replenish drinking troughs for livestock, or any other suitable receptacle, as outlined previously. In which case a tank would preferably be deep enough for the device to be hung or positioned inside the tank at some suitable depth and secured if necessary, so that when dry and open the valve would pass water to commence filling the tank and close shut by forming a kink some time after the water level had passed above it. With the valve remaining closed to the passage of water until some time after the water level had dropped to a level below the valve after which time the valve would again be exposed to air and dry out and open for refilling the tank. In this way the invention might be used in place of a conventional pressurised ball-float valve arrangement which is better suited to higher line pressures and to a clean water supply, to ensure more reliable operation. By their design ball float valves are prone to fouling and block up regularly from debris and accumulations in the supply pipe. In a variant of this the operation of the invention might be augmented with one or more floats or weights or counter-weights to achieve a desired performance.

The invention in a preferred aspect is thus a moisture responsive valve comprising a device in accordance with the foregoing, an operable valve closure, and a means to open and close the valve selectively on actuation of the actuation member and the design is scalable for manufacture in a range of sizes. In a further aspect the invention therefore provides an irrigation system including at least one and preferably a plurality of such moisture responsive valves as above described.

However, in the alternative, the principles of the invention may be employed, for example, in a moisture responsive sensor comprising a device in accordance with any preceding statement and as a means to generate a moisture responsive signal on actuation of the actuation member, or in a moisture responsive switch comprising a device in accordance with any preceding statement, as an operable switch for example comprising a pair of electrical contacts in familiar manner for connection to an electrical circuit, and as a means to open and close a switch selectively on actuation of the actuation member.

Any suitable known operable valve closure, signal generation means, or operable switch can be incorporated, externally and or internally, with the basic device of the invention to give the desired functionality.

In accordance with the invention in a further aspect, a method of detecting and/ or responding to changes in moisture levels in situ in an environment comprises disposing at least one and preferably a plurality of devices in accordance with the first aspect of the invention in an environment as part of a system designed to monitor and/ or control moisture levels in the environment; operating the system over time in such manner that as changes in the moisture levels actuate a change of state in the device in accordance with the first aspect of the invention a response is generated in the system.

The response may merely be observational (i.e. the device acts as a sensor) or may involve an operational response. In a preferred embodiment the response method includes taking steps to alter the moisture level in situ, for example to bring it back towards a desired predetermined level. Preferably, the device itself is configured to effect this, as a switch or valve actuator, and in particular as a valve as above described.

In accordance with this embodiment the method is a method of controlling an irrigation system comprising the steps of: providing an irrigation system comprising a network of irrigation hoses or the like fed from an irrigation fluid source or modifying such a network already existing in situ; incorporating into the network, in particular in the vicinity of one or more irrigation fluid delivery points, at least one device in accordance with the first aspect of the invention so as to act as a valve actuator, and preferably comprising as an actuation member a fluid conduit of flexibly resilient material in such mechanical association with the moisture responsive structure that distortion of the moisture responsive structure in the presence of moisture tends to mechanically distort the fluid conduit to introduce one or more kinks therein and thus to tend to inhibit fluid flow; operating the irrigation system as desired by controlling the delivery of irrigation fluid from the source to the network of hose outlets.

In accordance with the embodiment of the method, the use of the inventive device in situ at, at least one, and preferably at a plurality and for example all, of the irrigation fluid delivery sites in the system, irrigation is only delivered at those sites where it is needed when supplied from the central source. At those sites where moisture level is already relatively high, the device distorts and tends to close the valve/conduit. The valve/conduit is fluidly connected into the hose in the vicinity of the delivery point, and thus acts as a closure to the hose delivering irrigation fluid to that delivery point. Delivery points which deliver to sites that are already sufficiently watered are thus selectively closed in accordance with the method.

The irrigation source may supply irrigation fluid either on a constant-head or fixed volume basis, or on a time-based or volume-based periodic basis in familiar manner.

Precise control can be less critical however, since the use of the method of the invention limits a tendency to over-watering and to under-watering by selectively closing off those sites which are already sufficiently watered and by opening again more quickly and providing a viable opportunity for the further supply of water.

Irrigation fluid will typically be water, optionally including suitable horticultural or agricultural additives, such as a plant feed compositions or the like, water conditioning compositions such as pH control compositions and the like, in conventional manner.

The invention will now be described by way of example only with reference to Figures 1 to 19 of the accompanying drawings in which: Figure 1 is a perspective view from a generally hollow inner surface of a domed structure in a wetted, actuated state of a moisture actuated tube closure in accordance with the principles of the invention; Figure 2 is a perspective view of the same from a generally domed outer surface;

Figure 3 shows the same embodiment as figures 1 and 2 but before activation with moisture and in a perspective front elevation; Figure 4 shows in perspective a plan view of figure 3;

Figure 5 shows in perspective an underside view of figure 3; Figure 6 shows in perspective a frontal cross-section of figure 3; Figure 7 shows in perspective an endwise view of figure 3;

Figure 8 shows a first alternative embodiment of the figures 1 and 2 with a central aperture but before activation with moisture and in a perspective front elevation;

Figure 9 shows in perspective a plan view of figure 8;

Figure 10 shows in perspective an underside view of figure 8; Figure 11 shows in perspective a frontal cross-section of figure 8;

Figure 12 shows in perspective an endwise view of figure 8;

Figure 13 shows a second alternative embodiment, of a truncated cone shape with corrugations, of the figures 1 and 2 but before activation with moisture and in a perspective front elevation;

Figure 14 shows in perspective a plan view of figure 13;

Figure 15 shows in perspective an underside view of figure 13;

Figure 16 shows in perspective a frontal cross-section of figure 13;

Figure 17 shows in perspective an endwise view of figure 13;

Figure 18 shows in perspective a front view of a delaying device which may be incorporated into one or more of the previous embodiments;

Figure 19 shows in perspective an endwise view of the said delaying device in figure 18. Referring first to Figures 1 to 7, a device is shown which comprises a generally donned formation, similar to that of a shallow hollow spherical sector, comprising a thin-walled bi-layer of two polymeric materials (Thermo Plastic Elastomers - TPE's) with different water absorbency properties so configured that the bi-layer structure tends to be generally raised-up or domed when un-wetted refer to figures 3 to 7, and provided with a fluid tube connected crosswise to, on what is the outer surface of the dome when un-wetted, so that the fluid tube is generally straight and open bore, and when wetted, refer to figures 1 and 2, the bi-layer structure becomes geometrically inverted as a self-operating moisture responsive structure, causing the fluid tube to be located on the inner surface of the domed structure, which location distorts the fluid tube to occlude the passage of fluid with a kink formation.

The structure consists of a first layer or web of relatively hygroscopic polymer (1 ), suitably selected from materials including a high moisture regain grade of TPE from the range of commercially available PEBAX® materials also referred to as Polyether Block Amides. A second layer or web of relatively hydrophilic polymer (3) suitably selected from a low moisture regain TPE in the PEBAX® range or similar is, in this example, over moulded with the first layer or web to produce a thin-walled bi-layer moisture responsive structure. With careful tool design an over-moulding or twin-shot moulding process of plastic injection moulding lends itself to incorporating localised discontinuities and or perforation features (if these are required) during the moulding process itself. In an alternative process of manufacture more likened to fabrication as seen in the figures, the layers or webs may be firstly fabricated separately as nestable pre-forms by moulding, stretch or vacuum forming and punched or perforated as desired. The two materials are bonded together to form a moisture responsive structure which tends to change in dimension and to geometrically invert its initial formation, as is illustrated in Figures 1 and 2, when in the wetted state.

Figures 3 to 7 illustrate the invention in an un-deformed state, that is an un-wetted state, and better show the way the two layers interact.

With reference to Figures 1 to 7, an irrigation tube (5) conveniently of suitable waterproof polymeric material such as a low moisture regain TPE, is supported on the moisture responsive flexing member or structure formed by the two layers (1 ) and (3), via pairs of radial-like resilient extensions, projections or stand-offs (7) of the layer or web (3). These are of functional significance in the present embodiment, as in effect they, resiliently hold and restrain the irrigation tube close by each of its ends at a chosen crosswise alignment and distance away from the domed form of the moisture responsive layer or web (3), they also relay and magnify a pincer action to concentrate the compressive forces generated by the geometrical inversion of the moisture responsive structure, the bi-layer combination of (1 ) and (3), and this is enhanced by the mechanically advantaged arrangement of the irrigation tube (5) about its generally central region referred to as the kink zone (Z) roughly at the mid-point in the gap between them, at which point (8) the irrigation tube (5) is most likely to form a kinked discontinuity as it is distorted as the moisture responsive structure geometrically inverts, by the action following a period of wetting-up. This inverted wetted state is best illustrated in Figures l and 2. At this kinked discontinuity, the irrigation channel defined by the bore of the tube (5) tends to be occluded by the kink, and irrigation fluid does not pass freely through this point.

Figures 1 and 2 particularly, show the value of the mechanical advantage gained from off-setting the irrigation tube (5) from the moisture responsive structure i.e. the first layer or web (1 ) and second layer or web (3) in a bi- layer combination. The irrigation tube is mounted a short distance out from the outermost side of the second layer or web formation (3) and orientated and restrained by the radial-like extensions (7), (preferably, as in the figure, two pairs of radial-like extensions are employed).

The kink formation zone (Z) is located between the opposing radial-like extensions (7) and the effect is multiplied by the overall geometry directing the generated forces into a pincer (compressive) action applied through each end of the irrigation tube (5) as a consequence following the initiation of the geometrical inversion process of the moisture responsive structure comprising (1 ) and (3). Only one full kink can be formed in the middle of this zone and this may occur at some time from between a few minutes to several hours of contact with moisture - dependent on the device specification and intended application. By employing a flexible, resilient yet water-resistant second layer or web material (3) the process is fully reversible a great number of times.

This effectiveness and speed of operation is partly attributed to the fact that during the wetting up process and before the formation of a kink the irrigation tube experiences forces generally along its axis. The second layer or web of the moisture responsive structure is measurably stretched as it accumulates internal forces to resist against its progressive stretching as a consequence of the coupled relationship between it and the first layer or web. The moisture responsive polymer which readily expands when in contact with moisture creates expansive and opposing forces to those forces experienced by the second layer or web polymer.

As the wetting up process develops the surface area of the moisture responsive polymer increases to induce a progressive stretching of the lesser moisture responsive polymer. This tends to open out and flatten the geometry of the moisture responsive structure, making it more squat, i.e. as the first material expands and in particular extends and the second material is stretched elastically by this, the expansive forces and lesser resistive forces develop to a magnitude where the moisture responsive structure becomes unstable as it approaches a transitory flattened formation. In this condition the outer rim turns outwards and curls back upon itself to geometrically invert the structure and come to rest in a new opposing state of equilibrium, where the pent up forces are largely diminished. The forces responsible for this action are concentrated more so around the outer rim or periphery where most of the moisture responsive bi-layer material is present. In this state the wetted enlarged surface of the moisture responsive polymer is situated on the transposed outer surface of the dome of the moisture responsive structure, instead of as previously on the outermost inner surface. This is referred to as the first of two dynamic actions exhibited by the device.

This first action affects the stability of the tube member as the distance between its end supports is shortened and it is induced to collapse upon itself and preferably towards the moisture responsive structure to form a kink closure. This is the second of the two dynamic actions exhibited by the device. By careful design and materials selection the device can be optimised such that in practice, this collapse is likely to be a sudden transformation, so that the closure is in practice one half cycle of a bi- stable transition. From a domed appearance with the tube essentially open the valve suddenly inverts its structure into the shape in the figures 1 and 2. The motion can be readily observed and if the valve is laid out in a few millimetres depth of water, there is quite a rippling effect when this happens. The effectiveness of the invention is not dependent on this phenomenon alone as occurring always in the blink of an eye. For a range of device sizes and/ or materials the nature of the response can be tailored somewhat but the device should unless especially desired otherwise, when wetted-out as intended, form a complete and viable kinked closure of the tube.

In use in an irrigation system, the device may be incorporated such that the irrigation tube (5) is fluidly connected into an irrigation hose (not shown) on a distributed irrigation system in the vicinity of a watering point, for example at the outflow of a Tee'd off hose system. Irrigation fluid from a central supply reaching this point may pass through the bore unhindered if there is no kink present, when the vicinity is relatively dry. If the vicinity of the device becomes sufficiently moistened, the device will tend to an inverted and distorted state, and will tend to inhibit the through passage of irrigation fluid, acting as a closure at that point. Thus, the device of the invention acts in practice as a valve effecting automatic and reversible partial or full closure of the irrigation conduit at the point where the device is inserted into an irrigation system.

Figures 8 to 12 illustrate an alternative embodiment of figures 1 to 7 which differs in that the moisture responsive structure, comprising (11 ) and (13), has an aperture (19) in the central region, the purpose of which is to enable the device to be made more compact by reducing the height of the stand-offs (17) and so enable the mid-point (8) in the kink zone (Z) of the actuator tube (15) to partially occupy a space within the aperture.

Figures 13 to 17 illustrate a second alternative embodiment in the form of a radially corrugated, shallow, thin-walled bi-polymer truncated cone comprising material layers or webs of (21 ) and (23) respectively and with accompanying actuator tube (25). The device is capable of developing the same double-action of movement, i.e. its own geometrical inversion followed by the collapse of the actuator tube as in the earlier embodiments illustrated in Figures 1 -12. The purpose of the truncation serves at least two purposes one of which is to create an aperture (28) in the central region similar to that shown in figures 8 to 12 to enable the mid-point (8) in the kink zone (Z) of the actuator tube (25) to occupy a space within the aperture (29). The second purpose is to facilitate the physical provision of a number of corrugations radiating outwards from a central axis. The corrugations in radial arrangement correspond roughly to the elements of a basic truncated cone and provide the opportunity, without increase to the overall size of the device, to increase the area of the bi-layer structure and especially the exposed area of moisture responsive polymer very significantly over that of the previous two embodiments, to either increase the inherent power of response of the device by providing a thicker and more extensive layer of moisture responsive polymer (21 ) or advantageously to speed up the response of the device by thinning the cross-section of the moisture responsive polymer (21 ) whilst retaining the essential quantity of material necessary to ensure effective operation.

Desirably the moisture responsive structure is in a formation where the length of the developed periphery of the inner edge is close to or equal to the developed periphery of the outer edge. This has the effect of providing more moisture responsive material towards the inner region of mobility of the structure where it is most advantageously employed to geometrically invert through its central region, from one state of rest to an opposing state of rest.

A resiliently flexible elongate polymeric actuator tube (25) is again provided, and supported on paired radial like resilient extensions or standoffs of the layer or web (27). The fundamental mode of operation is the same as before, with the stand-offs (27) again serving to define a mechanically advantaged kink zone (Z) at which the tube member (25) is most likely to kink and become occluded in use.

When the whole of the surface of the moisture-responsive first layer is wetted-up, the expansive forces thus generated progressively increase the area of the first material against an escalating resistance from the second less moisture-responsive and resilient material which becomes stretched. This expansion also increases the developed length of the corrugations, around any radial line uniformly distanced from a theoretical central axis at the centre of the structure. If the bi-layer polymers are each of a consistent cross-section, the dimensional change will be disposed equally over the surface of the structure. As a consequence there occurs an outward expansion of the footprint of the structure, which at the start of the wetting process is likened to a corrugated thin-walled shallow, truncated conical structure or hollow radially corrugated raised disk, where the inner central corrugated periphery of the disk is generally displaced or on a different general plane from that of the outer corrugated periphery of the disk.

As the wetting-up progresses the higher concentration of corrugations and as a consequence higher bi-material content towards the central region, around the aperture, expand to force the structure towards a flattened yet still corrugated disc shape, i.e. the ends of the corrugations on the outer periphery expand also and at the same time become less pronounced as corrugations, as the structure is forced radially outwards to become essentially a flattened corrugated disk. This is evidenced only briefly as the condition is very unstable, i.e. when the general plane of the corrugated central portion of the disk aligns with the same plane as the general plane of the corrugated outer periphery of the disk. The axial movement of the structure develops further and causes the structure to invert its shape, through its middle region, and to reach a new state of equilibrium where the stresses are diminished, that is the inverse of its original state, i.e. where the wetted enlarged surface of the moisture responsive polymer is now situated on the outermost raised corrugated surface of the moisture responsive structure, instead of as previously on the innermost or recessed corrugated surface of the said structure.

This mechanical inversion of a corrugated thin-walled shallow, truncated conical structure can be evidenced in bi-metal devices which react to changes in temperature, for example in patent US 1 ,895,590 Spencer 1930.

The current invention is activated by changes in moisture and not temperature and employs polymers and not metals and possesses additional features which in combination achieve a new effect.

This action of the moisture-responsive structure affects the stability of the tube member as the distance between its end supports is shortened and it is induced to collapse generally towards the moisture responsive structure to form a kink closure. By careful design and materials selection the device can be optimised such that in practice, this collapse is likely to be a sudden transformation, so that the closure is in practice one half cycle of a bi-stable transition. From a raised three dimensional appearance with the tube essentially open, the valve suddenly inverts its structure to form a lowered, dished-like three dimensional structure, giving rise to similar if not the very same physical performance as described in the earlier embodiments illustrated in figures 1 to 12, and closes off the tube.

In Figures 1 to 17 the device of the invention is illustrated with the actuation member or tube (5, 15 and 25) supported on pairs of radial or near radial resilient extensions or webs or stand-offs (7, 17 and 27). This is particularly effective, as it holds the actuation member in a position relative to the moisture responsive structure, and defines a zone where the actuation member is most likely to kink when the moisture responsive structure is distorted.

Figures 1 to 17 demonstrate a number of operable embodiments of the device of the invention, as progressing from a relatively straightforward thin-walled bi-polymer domed or raised three dimensional structure, i.e. having the appearance of a hollow shallow spherical sector, to a modified version of same by the inclusion of a central aperture which aperture serves more than one purpose, to a third embodiment comprising a bi- polymer thin-walled, shallow formation of a hollow truncated cone. For anyone skilled in the art it will be evident that a number of further embodiments are possible based upon a raised or three dimensional bi- layer moisture-responsive structure. One of these would preferably combine the beneficial properties of the three embodiments disclosed, in the following manner, i.e. to include; the generally domed structure of the first embodiment, and incorporating the central aperture of the second embodiment, and where the said domed surface is undulated with corrugations similar to those of the third embodiment, but adhering to the general curved surface of the dome. Such a structure could be readily manufactured employing current co-moulding or over-moulding technology and posses a similar determination to invert its shape in the presence of moisture.

However, in a further modification it would be possible to provide a valve or actuator in any of the previous embodiments with the actuation member supported by modified resilient extensions or stand-offs, possessing one or a number of regions of weakness adjacent to one or a number of integral polymer hinges or pivot-like conformations. The purpose of which would be to introduce a time delay between the two mechanical operations namely (i) that of the geometrical inversion of the moisture responsive structure and (ii) the subsequent collapse of the actuator member to form a kink - for example a hysteresis effect to partially isolate the actuator member from the incremental movement of the moisture-responsive structure during the build up to a geometrical inversion, and preferably during at least a part of that inversion so that a more pronounced collapse and reinstatement of the tubular member is achieved by the delay built into the double action effect of the combination of movements (i) and (ii) as described above.

Whereas in my earlier published patent application I did refer many times to efforts to minimise or remove entirely the inherent hysteresis effects - this was a weakness in all of the prior art devices. On this occasion as in the examples described in Figures 1 to 17 it is possible and sometimes desirable to create a beneficial hysteresis effect by way of a delaying feature in the operation of either closing or opening, to ensure snappier transitions, i.e. shortly after the initiation of the geometrical inversion, in either direction of motion of the moisture responsive structure. Which reversions are now better defined in this invention than was the slow uncurling of my earlier invention where the full de-kinking or spring-back of the actuator member was almost entirely dependent upon its own physical properties. By incorporating a suitable delaying feature as illustrated in a general form in Figures 18 and 19 the opening and closing dynamics can be made snappier and more effective especially during the de-kinking part of the duty cycle.

Figures 18 and 19 illustrate the delaying feature which though shown as a modification of the figures 1 to 7 may equally be employed in the other embodi merits of figures 8 to 17 shown and the like. The moisture responsive structure comprising the bi-polymers (31 ) and (33) is resiliently connected to the actuation member (35) by two stubby sets of opposing stand-offs (37) and (39) of resilient polymer. A resilient run-around reinforcing planar rib (36) is also formed between the opposing stand-offs and connected to these to provide stabilisation and create at its generally mid-length a flexible hinge (40) as it turns back upon itself to progress from one stand-off (37) to link together another stand-off (39) creating at the same time open ended apertures or spaces on the outboard side of each hinge. The stand-offs (37) and (39) the rib (36) and the polymer layer or web (33) may be of the same material and preferably manufactured at one and the same time.

The combination of the flexible hinges and free spaces between the two halves of the ribs ensures a degree of movement of the moisture responsive structure independent of the actuator member and vice versa. Unlike my earlier invention, in this invention the delay effect is especially advantageous adjusting the performance of the de-kinking half cycle so that the moisture responsive structure has time to retreat a sufficient distance back from its wet inverted state. This action allows for a quicker and more deliberate full reopening of the actuator tube (to its full cross- section), which is a sought after property in a number of applications including those where the device is used to manage the flow of irrigation fluids.

The above examples are illustrative of moisture responsive devices which may function in effect as moisture actuated valves, in that distortion and dimensional change of the moisture-flexing element or responsive structure acts directly on an irrigation tube or actuator member to effect at least partial closure thereof in a wetter condition by direct mechanically advantaged action. This is a particularly useful embodiment of the invention, in that it uses the direct mechanical effect to minimise moving parts. However, as has been discussed above, the principles of the invention, to make use of the mechanical action of the moisture-flexing element or responsive structure on an actuating member retained thereon, are not limited to such direct closure, and can extend for example to the fabrication of sensors and switches where the distortion generates some other form of mechanical, electromechanical or electrical response, or hydraulic and/ or pneumatic actuation or signalling directly or indirectly, by the effect of the distortion of a suitable actuation member - such a response may originate from within or from without the said member.