GB2097555A - Electronically controlled irrigation system - Google Patents

Abstract

In an electronically controlled irrigation system, the actuation of a plurality of solenoid controlled distributor valves (6) is controlled by a central processor unit (P, Q, R, S) connected to a plurality of slave units (A.B.C.D) by way of a common signal bus (11) providing control signals and power supply to the solenoid valves. An interface (37) of the central control unit is caused to modulate the power supply by means of binary address signals, and each slave unit incorporates a code reading circuit and fixed address logic (2) arranged to respond to a corresponding coded address signal in order to actuate the solenoid (4) by way of appropriate control electronics (3). <IMAGE>

Description

SPECIFICATION Electronically controlled irrigation system This invention relates to the regular and controlled watering of golf courses, gardens, parks, greens, greenhouses, farm plantations and the like, and wherever there is a need for a number of water outlets such as sprinklers, sprayers, hoses, or any other form of watering device or outlet. Such outlet devices usually being situated at various points over the area to be irrigated, and such outlet devices being controlled, or turned on and off, eithersimul- taneously or sequentially by means of a remote electrical or electronic control system or device. Such systems are presently well known and are commercially available. However, these systems suffer inherent disadvantages which this invention is designed to overcome.

In order to illustrate the numerous advantages of this invention, present day practice will firstly be described hereunder, and the disadvantages of presently used systems will be stated in order that the advantages of this invention may be more readily recognised. The following example describes a typical system which is currently available, and in this example the system is assumed to be installed onto a golf course, although the principle as described is not necessarily restricted to use on golf courses.

It is common practice for golf courses to have watering devices on their tees, greens, and fairways.

These devices can total several hundred in number depending on the size of the golf course, the length of the fairways and so forth.

These outlet devices are more usually connected to a common water supply, usually by means of a rubber or plastic pipe network which is buried underground. The water-pipe network usually receives its water supply from a header tank which is in turn supplied by natural wells, springs, or the national water supply grid. The water outlet devices situated around the golf course contain electricallyoperated solenoid valves which enable the outlet devices to be switched on and off at some remote point, usually a Greenkeepers' Office or part of the golf club's building. Owing to the various limitations of the water supply network such as pipe sizes, water pressure and so forth it is usually possible to operate all of the water outlet devices simultaneously.Thus in order to maintain required water pressures and satisfactory performance of sprayers and other watering devices it is usual practice to turn the devices on and off in some sequential order. Further, since some parts of the golf course may require a longer watering time than other parts of the course, it is common practice for some form of electrical or electronic timing device to be associated with each water outlet solenoid-operated device. The above referred to timing devices are usually housed on, or in, a central control panel situated in a building such as a Greenkeeper's Office together with a mu Itiway switching device such as a uni-selector which is used to sequentially select, or switch, individual solenoid devices via a pair of cables dedicated to each solenoid device.

Figure 1 illustrates a typical electrical arrangement for a system such as that described above. For simplicity, a system capable of sequentially operating only four water outlet devices has been illustrated although in practice a typical system would operate several hundred devices in similar manner.

Referring now to Figure 1, all circuitry contained within the control panel is drawn in the area M-N-P4-M. The mains electricity supply is fed via a mainswitch 1 and fuse 2 to the primary P of transformer 3, the secondary 5 of which produces a lower and safer working voltage for the solenoid drive system. An electric or electronic clock mechanism 4 records the time of day continuously and is the type which contains pairs of contacts which can be preset to operate at a chosen time. This clock 4 is mounted on the panel and is used to pre-setthe time at which a watering cycle is due to start. At the chosen time clockmotor 4 causes contact pairs 5 and 6 to close. This in turn energises relay coils 7 and 8, and simultaneously, operates uni-selector motor 9 which in turn causes uni-selector arm 10 to rotate one "step" to position A.Relay 8 now deenergises closing contacts 11 whilst relay 7 remains energised via its own contacts 12 and contacts 11. A short time later (typically one minute) clock motor 4 further advances and re-opens contacts 5 and 6 in readiness for repeat operation 24 hours later, but relay 7 and uni-selector arm 10 still have a voltage feed maintained owing to contacts 11 and 12 being closed. As soon as uni-selector arm 10 has reached position A, the first watering device 13 is energised together with electronic pre-settabletiming device 14. Watering device 13 will now remain energised until the preset time lapse on timer 14 expires, whereupon timer output contacts 15 close which in turn causes uni-selector motor 9 to step the uni-selector arm 10 onto position B.Thus first watering device 13 and timer 14 become de-energised, contacts 15 re-open, and the second watering device 16 and timer 17 become energized.

The above-described process is repeated, timer 17 actuating contacts 18 at the expiry of its preset time period, causing uni-selector arm 10 to be switched to position C. The process is repeated for third watering device 19 for a duration of time preset on timer 20, and again for fourth watering device 21 and timer 22.

At the end of the time duration for the fourth watering device 21, timer 22 causes the uni-selector arm 10 to be returned to position E. This causes energisation of relay 8, which opens contacts 11 thereby de-energising relay 7 which opens contacts 12. Thus the uni-selector and watering control low voltage circuit remains in its resting state until clock motor4 re-closes contacts 5 and 6 and initiates the whole cycle again the following day. The wires 25, 26,27, 28, 29,30,31,32 feeding the watering device solenoids are more usually fed underground to their destination points and the use of multicore, or multiway cable is common with electrical junctions and terminal boxes at various points around the golf course.

The main disadvantages of previous systems as described above are: (i) The use of multiway cables and separate wires for each solenoid device is expensive from the view point of cable cost and installation, which can total several miles of wire on a large complex.

(ii) If a wire becomes broken it is difficult to deter- mine exactly where the break has taken place. By way of example, referring now to Figure 1 assume that wire 29 becomes corroded or broken at some unknown point beneath the golf course. Now because this break will prevent the third watering device 19 from operating in the example illustrated, all that can be deduced by reasonable intelligence is that the fault has occured somewhere between the panel and the third watering point This could cover a considerable distance and the cable could be laid under numerous greens and fairways. The job of tracing, excavating and replacing cable is very expensive, time consuming, and disturbes the very grass and plantation which the system is intended to preserve.Furthermore, the task of tracing and rectifying such faults is often traditionally carried out by Greenkeepers and contractors who are better trained in aspects of lawn keeping than in aspects of electrical engineering. It is quite common for the equipment to suffer damage owing to the ignorant but well intended efforts of a Greenkeeperto repair a multiway cable which has become accidentally severed by means of a tractor, spade, or even occasionally by digging animals, such as a badger. Referring nowto Figure 1, it can be seen thatthe shorting of wires 25 and 26 for example would possibly cause irrepairable damage to transformer3.Such occurence is not unknown, particularly if a multiway cable becomes severed at some point by means of a clean steel blade or implement (iii) Use of a control system as described is fairly restrictive insofar that a watering sequence must take place in the order set by wiring to the uniselector outputs. By way of example, and referring to Figure 1, the watering sequence will always be device 13 first, followed by 16, then device 19 and finally device 21. If, for example, it was desired to give a second watering period at (say) outlet 21; then the whole cycle would need to be initiated for a second time within the 24 hour period. Since watering usuallytakes place by night, this would normally require the attention of a Greenkeeper during abnormal hours.

(iv) In the event of a mains supply power cut, then the main clock would cease to be energised. When the mains supply subsequently becomes restored, the automatic watering cycle would now commence later than intended, with somewhat disasterous consequences if a Golf Tournament was taking place at the time.

(v) It was stated earlierthatthe irrigation water system is supplied from a header tank, via a pump which provides water pressure and flow. The pump is normally switched automatically via a relay which is in turn operated from the low voltage circuit within the control panel, so that the pump is operated for the duration of the automatic period. Referring now to Figure 1, a suitable output drive for such a pump relay would be item 33. A disadvantage of this typical system is in the case where a Greenkeeper during his daily journey of inspection may well decide to use water for some purpose at some remote point on the golf course complex. This decision would normally require him to return to the pump station or control panel in orderto operate a manual pump switch, and then return to the location where water is required.At the completion of his work he then has to return once more to the control point in order to switch the pump off. The whole operation can involve a total of much time and distance.

(vi) Awater outlet device cannot normally be used electrically at anytime at will by a Greenkeeper unless he first returns to the control panel and resets the panel clock and timer sequence to suit his immediate needs. He is then later required to return once more to the control panel in ordertoturn off the selected device and re-programme the clock and timers. This can be very time consuming and if he forgets to reset the clock and timer devices, the next intended watering cycle will not take place.

(vii) Since on current practice systems, the control panel requires a separate timer, and separate wires for each individual solenoid operated device, it can be seen that a typical installation becomes somewhat expensive and complex both in terms of equipment contained within the panel, and in terms of outdoor wiring.

(viii) The typical system as described above operates independently of prevailing weather conditions.

Thus with the system as described above, the automatic daily watering cycle would take place even on days which had had a heavy rainfall, and would thus distribute water unnecessarily.

(ix) If for some unforeseen reason one or more of the water distribution pipes beneath the golf course were to become corroded, cracked or severed, the typical system as described would merely pump water away through the pipe break during the automatic watering cycle, thus wasting water; possibly causing flood damage at one point, whilst not providing any or sufficient watering at other points. This fault condition could go undetected and unrealized for some considerable period of time on a large complex and possibly result in long term damage which is not apparent initially.

(x) In the above-described typical system, if for any reason the header tank becomes empty owing to a leak, or non-replenishment it would be possible for pump damage to occur when it next became actuated.

(xi) Afurtherserious disadvantage of typical present day systems occurs when a normal long watering sequence takes place during the busy golfing season. It may well be that for a period of two or three weeks in (say) August there is a programme of long all-day golfing to take place, each to commence in the early morning and to end not until well into the evening. This in turn may well allow insufficient "out of play" time to enable the complete watering sequence to take place throughout the night. This normally gives a Greenkeeperthe choice between: (a) Aborting the automatic cycle before it is completed, or (b) resetting the sequence each day so that all points get watered over (say) three of four days total period.

With choice (a), the inevitable result is that the last most points in the automatic cycle will not become watered at all. With choice (b) the Greenkeeper needs to attend and re-programme the panel each day during a period when his services are very much required elsewhere and time is valuable.

(xii) A further disadvantage of currently used systems such as described above is that the system cannot be easily modified or extended without considerable alteration and addition to the buried multicore cables and without alteration to, or extension of, or the replacement of the central control panel.

(xiii) With the requirement of one pre-settable timer for each solenoid driven watering outlet, in addition to the main clock controls and so forth, it can be seen that with a large multistation complex the number of panel controls, dials, etc, is high and hence operation and setting up of the control panel becomes complicated and time consuming.

(xiv) In many cases where control panels are situated, the environment is far from ideal. The buildings may be dirty and/or damp. The building may be used for other purposes such as storing tools ortractors, or fertilizers and chemicals, or boiler house fuel.

In the case of a granary fine dust in the air can cause problems since it is one further intention of th is invention that the solenoids could be used to operate heater air flaps and the like for the purpose of drying grain. Thus the entry of dirt and moisture to the interior of the control panel via front panel switches is common experience; as is accidental damage to protruding parts such as switch control knobs and toggle levers.

(xv) A further disadvantage of currently-used systems lies in the difficulties of driving solenoids over both short and long feeder wires. A solenoid which is situated a long distance from the control panel may well be under powered owing to voltage drops and power losses along the feeder cable. If the panel output voltage is raised in order to overcome this problem, then these solenoids which are fairly close to the control panel may be overpowered with consequential damage owing to heat generated in the coil of the solenoid.

(xvi) During the winter months when a typical system can be out of use for several months, the effects of dampness can cause corrosion to relays and uniselectors and to switch contacts located within the control panel. Switches and uni-selector devices are difficult to seal hermetically whilst still rendering them accessible for lubrication and servicing. Thus after a winter period it is quite common for internal dampness and corrosion effects to renderthe control panel both unreliable and potentially dangerous.

It is the purpose of the present invention to overcome all of the above listed disadvantages inherent in previous systems in addition to providing a more flexible and useful concept. One embodiment of the present invention will now be described, by way of example, making reference to Figures 2 and 3. To be consistent in description with the previous example, the inventions use as applied with a golf course will be assumed; however, no such restriction of use for the invention is envisaged and other uses are foreseen in greenhouses, farming, granary-control (wherein the solenoids may be used to actuate air flaps), and certain industrial applications are also envisaged in the fields of process control, streetlamp switching and other applications wherein a number of electrical loads need to be switched remotely via a common control wire.By way of example, Figure 2 illustrates the simplified outdoor wiring required with one embodiment of the present invention as could be applied to part of a golf course. Items T1, G1, F1.1, F1.2, T2, G2, F3, G4 are all solenoidoperated water outlet devices each of which contains, in addition to an electrically operated water valve, an electronic circuit which is so designed and constructed asto respond and react only upon receipt of a unique digital code, particularto itself.

Each solenoid device therefore is designated its own individual "address code", or binary pattern. This binary pattern may be transmitted in several alternative forms. In one embodiment of the present invention, the address codes are transmitted via a common control wire which is connected to each solenoid which forms part of the network. The digital codes may be transmitted in such manner that a logical "1" is represented by one voltage, and a logical "0" is represented by a different voltage. In a further embodiment of this invention the digital codes may be transmitted in an alternative manner in which a logical "1" is represented by a voltage of one polarity with respect to earth, or reference 0 volts, whilst a logical "0" would be represented by a voltage of the opposite polarity.In one further embodiment of the present invention, the digital codes may be transimt ted in such manner whereby the logical "1 " and the logical "0" are transmitted as two different frequencies, or alternatively may be two similar voltages or frequencies, but wherein the difference between a logical "0" and a logical "1 " is determined by differ- ences in pulse width or signal time duration. The control wire over which the solenoid address codes are transmitted may be a signal wire which is quite independent of the power cables which convey electrical energy to the solenoids, and may or may not share a common earth, or 0 volt return wire in common with the solenoid power.

In a further embodiment of this invention, a separate command, or signal, wire is not used, but instead the digital intelligence is superimposed upon, and transmitted via the same cable, or wire, which is used to convey power to the solenoids. In the case wherein the address-code wire, and the solenoid power wire are one and the same, then the method of transmitting logical "0"'s and logical "1 "'s can be based upon any of the above-described methods of digital coding, and further, the electrical energy used to power the solenoid coils, and to power the electronic "address circuits" may be in either alternating or direct current form. Each of the electronic circuits associated with the solenoids may be constructed so as to "recognise" more than one code so that one code may be used to turn a particular solenoid "on" whilst another may be used in order to cause the same solenoid to switch of again.

In one embodiment of this invention, each solenoid drive-electronic assembly may contain a rechargable battery which is charged via the power feed cable, or alternatively may contain a bistable latching type relay in order that the last received digital code command is not lost should the power feed become temporarily interrupted. In an alternative embodiment of this invention, no batteries or latching devices are contained within the solenoid address circuitry, and the electric codes are used only to switch solenoids "on". In order to reset, or turn solenoids off again, the power supply is tem porarily interrupted at source.

Referring again to Figure 2, it will be seen that in this example of the invention, all of the solenoid/electronic-address units are connected by a common 2core cable which conveys all digital code signals as well as solenoid and circuit operating power. This 2core cable is likely to be a twin-core cable in the normally accepted sense, however this is not necessarily so because in one further embodiment of the invention, only one power/signal wire is used; the electrical "return" path utilizing the earth; and water contained within the water pipe network which feeds the outlet devices.In yet one further embodiment of the invention steel or other metal is used for water piping and thus the pipe acts as one of the signal cables, or earth, and in still one further embodiment, the water is completely contained within pipes of plastic or other insulating material, and the water system is so engineered as to ensure that the water in the system is electrically isolated from the earth. In this particular embodiment the water may be used as one supply/signal conductor; the earth constituting the other. The essential cable requirements of the embodiment illustrated in Figure 2 is that all of the devices are connected together by way of a common 2core and also, by way of the same cable, to the output of a special-purpose control panel, which is likely to be situated in a build ing such as a Greenkeeper's Office or storeroom.To achieve this requirement it is only essential to install the cable from output A to the first solenoid device at B, continue on via C, D, E, F, G, H and J. The continuation of the cable from pointJ in Fig. 2 back to the control panel output K is not essential, but is considered desirable for the following reasons: (i) The power loading on cables is shared via two current paths in similar manner to a "ring main" in the normally accepted sense.

(ii) With the cable system connected as a "completed ring", then one complete cable breakage could occur without detriment to the system operation provided that the cables broken ends were not to become shorted together. To illustrate further, suppose that a cable break were to occur between points F and G in Figure 2. The electrical feed to solenoid T2 would be A-B-C-D-E-F whilst the feed to solenoid G2 would be via K-J-H-G. Thus with this one breakage in the electrical cable network, the system operation will not be diminished. If at some sub sequent time a second breakage occur in the cable at, say at point Yin Figure 2, then the only solenoids which will receive neither power or command sign als will be those which are electrically situated between the two points of wire breakage; namely devices G2 and F3 in the example shown in Figure 2.

By simple logical deductions a Greenkeeper or contractor could easily calculate that one wire breakage must be between G4 and F3 in the example illustrated, and that the other must be between T2 and G2. In the case of the system not being connected as a complete ring, i.e. wire J-K not installed; then if a single wire breakage were to occur, then all devices on the outward side of the breakage would fail to operate; i.e. devices G2, F3, G4 in the case of the example.

(iii) If the breakage were to occur between points F and G as previously described. In this case tracing a faulty cable is simply a matter of knowing that a break has occurred between the outermost working device and the innermost non-working device.

Referring again to Figure 2, since all of the solenois devices are connected in parallel across a common pair of wires, then it follows thatthe geographical route taken by the cable, and the order in which it encounters solenoid devices to which it is connected, does not necessarily have to follow the normally accepted route and location numbering system used to identify various places around the complex from the viewpoint of playing a game of golf. For example, it is normal to commence a game of golf from a point known as the "First Tee" and then to proceed via greens, fairways and tees in ascending numerical order. The cable is likely, but does not necessarily have to follow the same route, but may well take shorter geographical routes and thus encounter the various solenoids en route in a "non-golf" order.This is most likely to occur whenever the older multicore systems are being substituted by the present invention. It is envisaged in this case that a two wire distribution system will be made up by utilizing individual wires which have remained intact between various points around the complex in which most of the remaining multicore conductors have become broken, corroded, damaged or lost.Thus by salvaging at least some of the wiring from an existing installation which has deteriorated beyond multicore use, it may be possibleto "patch up" a 2-wire system for use with the present invention, without the need to excavate the whole of the golf course mute. Referring again to Figure 2 it will be seen that the method used for numbering the individual solenoid devices does not necessarily proceed in numerical ascending order, 1,2,3,4,5 N N where N= total number of sol- enoids. For example, to speak of "Water Outlet No.

273" does not give any clue to its geographical location on the golf course complex. Thus in coding the devices and in programming their desired operating times and sequence, to be described later, a numbering system has been devised for use with those embodiments of the invention which are intended for golf course use. In the example of Figure 2, device 'T1" is that which is used to water Tee No. 1, "T2" is that for Tee No.2, and soon "G1", "G2" and "G4" are those devices used to irrigate greens 1, 2 and 4, respectively. Fairways being long strips of land may well contain more than one solenoid device, and in the example of Figure 2, then the device number F1.1 or Fl -1 or F1/1 would be taken to be that which is used as the first water outlet device on the first fairway, whilst F1.2, F1 -2 or F1/2 would be used to designate the "second device on Fairway No. 1". In similar manner a solenoid device which is coded "G3-2" would be taken as "Green 3, device 2", whereas "F14/6"would be taken as "Device No.6" on the fourteenth fairway.Referring again to Figure 2, the dotted device, designated G15, as an example, represents a device to be added at some future date, whereupon the only addition to the network, apart from the device itself would be to "break in" to the twin wire feeder in order to connect the new device and the addition of any extension water piping which may be necessary depending upon the new devices intended geographical location in relation to the previously installed plumbing. The object of adding one further device to the system example of Figure 2 is to illustrate that any future addition of solenoids/watering devices (up to a maximum number) required no mechanical, electrical, or design alterations to the central control panel as would have been the case in previously systems prior to this invention.Neither is there a requirement to install an extra feed wire beneath the ground from the control panel to the newly selected location as there would have been with previously used systems. The only task to perform at the control panel, following the installation of an additional device to the system is to "key-in" or programme its number (e.g. "G15") and operating time duration in a mannerto be later described.

In the previous examples of this invention stated above, individual solenoid devices are operated sequentially by the regular transmission of "address" or "command" codes which are transmitted from the central control panel to be later described. In order to operate more than one device simultaneously, it is necessary only to ensure that these solenoid devices intended for simultaneous operation contain identical electrical address codes, although this feature would not necessarily be necessary (or useful) in the case of a golf course since in one embodiment of the present invention, several devices could be turned on in rapid succession merely be serially transmitting all of their individual codes.Similarly they could be turned off in the same manner in one emboidment of the invention, or alternatively in another embodiment of the invention they could be simultaneously deenergised merely by causing a momentary interruption to the power supply. One embodiment of the control panel and associated equipment which forms a part of this invention will now be described, by way of example, with reference to Figure 3. For consistency of description with previosuly stated example, reference will be made to the inventions use as applied to a golf course: however, no such restrictions of use is proposed or intended.

Referring nowto Figure 3, the apparatus contained within the area A-B-C-D-A is, in simplified form, that which constitutes a "solenoid-operated watering device" and comprises a voltage regulator 1, a code-reading circuit and fixed address logic2 which electrically identifies the device; control electronics 3 which responds to the correctly received address code and switches solenoid 4 by means of S.C.R. or similar electronic switch 5. Regulator circuit 1 is to reduce the incoming line voltage to a level suitable for solenoid energisation: thus the transmitted power line voltage can be sufficiently high to overcome volt drop problems associated with long cables, whereas the regulator prevents damage to those solenoids which may be geographically close to the transmission point where the line voltage may be high.In one embodiment of the invention regulator 1 allows a high voltage to be impressed across the solenoid when it is first energised in order to obtain high Ampere-Turns, but reduces the level once the solenoid valve has completed its travel and requires only a maintaining current.

Referring again to Figure 3, the energisation of solenoid 4 causes valve 6 to open and distribute water via outlet device 7 which could be a sprinkler; the water entering by way of pipe 8. Pipe 9 continues around the complex to feed other and similar devices. Solenoid 4, when energised also closes contacts 10 in one embodiment of the invention and by-passes the electronics circuitry in orderto minimise use of electronics circuitry once the solenoid has been energised in order to minimise the need for electronic component heat-sinking; power consumption and so forth. In the example of Figure 3, wire 11 is the conveyor for both solenoid power, and for command data signalsto all solenoid devices connected to the system.Each solenoid device may have a push button 12 attached to it and so wired internally that when pressed, the electronics circuitry is by-passed and the solenoid is turned on. The solenoid may then be "latched" on the way of contacts 10, or by electronic means. Thus a Greenkeeper may be provided with means of switching the solenoid device on locally at any time without the need to return to the control-panel point. This feature will be especially useful when "priming" the water system after a long period of dis-use when it may have been previously drained for winter shut down.Similarly, a further button 13 (which has two poles in the example of Figure 3) may be installed as part of the watering device apparatus which enables that device to be turned off at any time (locally) without the need to return to the control panel location, irrespective of whether it had been previosulyturned on manually by means of its local button 12 or alternatively by means of command signals previously transmitted by the central control panel. Referring again to Figure 3, the apparatus contained within the area E-F-G-H-E, is likely to be contained in and around the building in which the control panel is situated and constitutes parts of a completely installed system, as applied to golf courses and similar applications. In this example, the systems water supply is stored in header tank 15 which also contains an electrical float switch 14 used to inform the central control panel thatthere is (or is not) enough water to enable the pumps to be actuated without the risk of damage which might otherwise occur if for some reason the header tank becomes empty and the pumps are run dry. Water pressure in the pipe distribution network 8,9, is provided, when required, by means of main pump 16 which in a large capacity system may need to be initially "primed" by means of a smaller "priming" pump 17. The two pumps are normally oper ated from a one, two, or three phase electrical supply and are switched via heavy duty contactors 18 and 19 which in turn are switched from the control panel to be later described.All electrical power is derived from mains supply 20 and is fed via main switches and safety trips and fuses 21. Three pressure sensing devices, each containing electrical contacts and each calibrated to switch at different pressures are fitted to the outlet side of main pump 16. These pressure sensors are designated in Figure 3 as item 22 for very "low" pressure; 23 to sense an intermediate, or "medium" pressure, and 24 to sense a "high", or maximum pressure.

One further apparatus connected as a peripheral device to the main panel consists of a plastic (or insulating material) bucket fitted outside of a building. This plastic bucket 25 contains two electrodes 28 and 29. During heavy rainfall, the electrical resistance between electrodes 28 and 29 reduces owing to the bucket 25 becoming full of water. This information is "used" by the control panel to detect a recent fall of heavy rain and so abort an intended watering cycle. At regular intervals of time, the panel can be programmed to operate solenoid valve 26 allowing any collected rainwater to be discharged by way of drain 27 in order to avoid the same rainfall from being "sensed" more than once.

One embodiment of the control panel which forms part of this invention is represented in Figure 3 wherein the apparatus which, in total, constitutes the control panel assembly is illustrated in simplified form within the area designated P4-R-S-P. The more essential features contained within the control panel assembly are: (i) Power supply unit which produces all voltage levels required internally by the control electronics: the various sensing devices 25, 14,22,23,24 and others which may be added; and the solenoid operating voltage which is distributed via cable 11 to the various and numerous solenoid operated devices around the complex. The power supply unit is shown as item 28.

(ii) Mainswitch 29 and panel main fuse or protective device 30 which is in turn fed from mains supply 20 via main switchboard 21.

(iii) Interfacing electronics which interfaces the various externally connected sensors and pump contactors with the remaining internal electronics circuitry.

This interfacing is shown in block form as item 31 in Figure 3.

(iv) A microprocessor device 32 which forms the "heart" of the control system; in addition to memory circuits 33. Some of the memory locations in 33 will store fixed and unalterable instructions which control the systems basic behaviour and characteristics, whereas other parts of the memory 33 will store coded information and instructions relating to a chosen pattern of behaviour, or watering sequence cho sen by the operator, or Greenkeeper. Other parts of memory 33 will be used to temporarily store data whilst the microprocessor 32 is in the process of executing its instructions. In the example of Figure 3, essential circuitry such as microprocessor system clock pulse generation and so forth, is deemed to be included as part and parcel of the microprocessor circuitry 32.

(v) Real time clock-integrated circuit device which accurately records the time of day on either a 24 hour basis or a 12 + 12 hour basis, in addition to recording the day of the week 34. The real time clock circuitry and associated parts is represented by block 34 in Figure 3.

(vi) Rechargeable battery,35, (together with associated charging circuitry) which is normally kept charged by way of power supply unit 28. This battery 35 in one embodiment of the invention is to maintain the status of all memory 33 and real time calendar clock 34 in the event of the main supply 20 being temporarily disconnected, or in the event of mains witch 29 being turned off, thereby maintaining all programmed instructions intact; in addition to preventing the late starting of a watering cycle subsequentto a power cut.

(vii) Code pattern generator 36 which receives instructions from microprocessor 32 and memory 33 and formulates address codes in suitable format for subsequent recognition by the solenoid devices. For example, what may be programmed by a greenkeeper as Fl 1/3, to use the previously explained notation, may well be represented by a differnt and individual binary pattern for the purpose of data transmission along cable 11.

(viii) Power-tocable and code-to-cable interface electronics 37 which receives and combines both coded command signals and solenoid power voltage and enables both to be transmitted outward via a cable or conductor 11, and which can further be switched by way of microprocessor 32 so as to cause a momentary interruption of all transmission in order that all powered and energised watering devices may be reset to "Off" in one embodiment of this invention, as previously described.

(ix) Display means which may be in the form of various types of indicator lights; light -emitting diodes; numerical displays (either L.E.D. or L.C.D.) or suitable combinations thereof; the purpose of which are to indicate the time of day; status of system; water pressures and all other useful and relevant data required by an operative. In an alternative embodiment of the invention, some of data readout devices 38 can be replaced with a video c.r.t and associated circuitry and the microprocessor system is programmed in order that the information to be displayed is characterised in the mother tongue of the country in which the system is to be used. By way of example the video system could be caused to generate a word pattern such as: "Device No. F18/2 operating 3 minutes to run Time now 04.00 Hrs.

Day: Monday" and alternatively other messages such as: "Low pressure - suspect broken pipe or Pump failure" and other messages in addition such as "No cycletoday-rain gauge full".

Word generation and video presentation is of course well known art; however, its use as part of the present invention is unique.

(x) Data bus, or data highway 39 which is a system of interconnecting conductors in the accepted sense of microprocessor and computer technology and which is used to interface the various internal circuits with each other within the control panel assembly.

(xi) A keyboard comprising a number of press buttons used to programme a desired watering sequence; to set the real-time clock initially, to alter any variable and to request information. This keyboard 40 may be made from normally accepted push buttons: however, in at least one embodiment of the present invention it is more likely that all front panel control and operating buttons will each be incorporated as a "touch-sense", flat assembly, and which form an integral part of the panel itself. This concept is further illustrated in Figure 4 and will be more fully described later.

Using, by way of example, one embodiment of the invention illustrated in Figure 3, some of its operating features will now be more fully described, from the Greenkeeper's, or users, viewpoint.

Various restrictions may be "typed into" the memory by way of keyboard 40. One such restriction will be what shall be known as the "forbidden time period", which are two times in a particular day or days (say, 08.00 hrs. to 17.30 hrs. on Sunday) between which no automatic watering shall take place.

Other data entered via keyboard 40 will includethe sequence in which the various solenoids are to be driven; the time duration for which each solenoid is to be energised; the number of times per day (or night) which each sequence, or part of a sequence, is to be repeated, and so forth. In operation; owing to the high number of watering devices connected to the system it is possible that the total watering time programmed may exceed the time available throughout the night, and before the start of the next "FORBIDDEN TIME PERIOD", the desired sequence may not have been completed. This problem will be compounded if there has, in addition, been a temporary power failure during a night, or "safe" period.

A feature of this invention is that when the start of a "FORBIDDEN TIME PERIOD" is reached, the point in the watering sequence is "remembered" until the forbidden period is past whereupon watering can recommence again. For example it may be that "Tees" are watered twice per night for3 minutes; "Greens" once per night for a number of different time periods depending on soil conditions; and that the fairways be lastly watered in sequential order up until the start of the "FORBIDDEN PERIOD". On the next occasion, all "Tees" and "Greens" are sequentially watered again, whereas the watering of fairways is started from the point at which the cycle was halted on the previous day. Thus over a period of several watering cycles, all fairways would have at some time received water.

By way of example the following could be a typical golf course watering programme to be instructed by means of suitable operation of keyboard 40: "Forbidden Times - 08.00 through 16.00 Sunday.

08.00 through 18.00 Mon, Tue, Wed.

09.00 through 18.00 Thu, Fri.

No watering Saturday.

Watering sequence: T1 through T18 -3 minutes each Repeat T1 through T18 3 times daily.

G1 -3 minutes.

G2, G3, G4 - 5 minutes each.

G6 -4 minutes.

Repeat G2 through G6 4 times daily.

G7 through G18 -7 minutes each.

Fi-1 through F3-6:-15 mins. each everyday.

F4-1 through F17:-30 mins. each one day in every 5 days.

F18-1 through F186:-30 mins. each".

In this example, if the planned irrigation program had not been completed by the time of start of the forbidden period (say, 09.00 hrs. on Thursday, for example), then the watering would be halted. If in this example device No. F14-1 had been the last operated device at this instant in time; then at the following allowable period the system would commence by irrigating all Tees and Greens; followed by F1-l through F3-6 and would then"skip" to drive device No. F14-2 thus continuing the pattern which had been previously halted.

It is a further embodiment of this invention that any programmed sequence can be revised by way of keyboard 40 at anytime without the need for complete reprogramming of an entire sequence, or set of instructions; and further, that all programmed instructions and all evets which are taking place at any one instant in time can be easily read and noted by display means which may consist of a video c.r.t., L.C.D. or L.E.D. displays, lamps or other display means or any combination thereof. Thus a versatile control means is provided allowing a variable and complex set of instructions to be carried out; and furthermore, a sequence which is running late, or a sequence which requires a longer time period than that allowed is (a) prevented from continuing during "forbidden hours", and: (b) is completed during a later (allowable) time period.

A further feature of the present invention will be now described, again with reference to Figure 3, and will establish the purpose of the three pressure sensing devices 22,23 and 24.

Device 24 senses the normal high pressure which the pump is required to maintain for efficient system operation. During an automatic irrigation cycle pump 16 is caused to maintain the water supply and will only switch off if device 24 senses excessive pressure. When device 24 senses the pressure to have fallen below "normal" working pressure, then the pump will again be energised by way of electronics control 31 and contactor 19. In a large capacity system incorporating a priming pump, then at the start of an automatic irrigation cycle, the priming pump may first be caused to operate until the system has achieved some lower pressure before main pump 16 is allowed to operate. Such arrangement could be achieved whereby pump 17 is a priming pump, switched by way of electronics control 31 and contactor 18; and whereby device 22 is used to sense the (low) priming pressure which must be achieved before pump 16 can operate.

It is a further feature of this invention that if, once primed, the water pressure falls to the low level sensed by device 22, or alternatively if the priming pump runs for more than an allowable preset-time period (which time period may be programmable by way of keyboard 40 and which may be retainable in memory 33 of by other means) without the low pressure level being surpassed, or re-surpassed, then the entire irrigation system shall be shut down, pumps 16 and 17 shall be inhibited and suitable indication shall be displayed on the control panel visual means.

Such indication could read or indicate the message: "Low Pressure - suspect pump failure of broken pipe".

It is one further feature of this invention that if during a non-automatic-irrigation period, the water pressure should fall to some "medium" pressure, (less than that sensed by device 24 but more than that sensed by device 22), then main pump 16 shall be actuated so as to cause the pressure to be increased once more to the maximum pressure as sensed by device 24 and maintained for a minimum time period of, for example, 15 minutes. The above so-called "medium" pressure is sensed by way of a third pressure sensor 23.Therefore, if a Greenkeeper connects a hose pipe to the system at some remote point on the golf course, or alternatively if he manually operates one or more of the solenoid devices either locally on site, or by means of control panel keyboard 40, then the decrease in system pressure so caused will be sensed by device 23 and subse quentlythe system water pressure will be restored.

The above-described feature will also compensate at regular intervals, or irregular intervals for any small or gradual leaks in the water pipe network. This feature also eliminates the Greenkeeper's need to switch on pumps when drawing water from the sys tem and further eliminates his need to switch a pump off when his task is completed.

It is a further feature of one embodiment of this invention that, just before the start of an automatic irrigation cycle, or sequence, or at any other pre determined regular daily time, the electrical power supply to the feed wire 11 can be momentarily interrupted by means of microprocessor 32 control such that any solenoid device which is connected to the system, and which may at that time be operating, is nowde-energised. One use of this feature is to switch off a watering device which may previously have been inadvertently left on.It is a further feature of this invention that, referring again to Figure 3, rainwater may be collected in a suitably placed plastic bucket 25 containing electrodes 28,29, as previously described and connected to the control system via suitable interface circuitry 31 such that an intended irrigation cycle is aborted if electrodes 28 and 29 sense the presence of collected rainwater. In such event, the control panel display can be caused to to display a suitable message, or lamp, to indicate that the cycle was aborted due to adequate collection of rainwater. The above-described rainwater device can be drained at regular intervals by way of the micro-processor system causing actuation of drain solenoid valve 26.

It is one further feature of this invention, referring again to Figure 3, that a water supply header tank 15 may contain a floatoperated electrical switch device 14 which is connected to the main panel control system by way of interface electronics circuitry 31. The purpose of this feature is to prevent any water pump from being enabled to operate in the event of an insufficient supply of waster in the tank 15. Such an event could cause an illuminated display or message to be produced by the display means 38; such message could read, or indicate "Low water supply" or similar.

Referring again to Figure 3, it is still one further feature of the present invention that a form of electrical current limiting be incorporated within the output-interface circuitry 37 contained within the central control panel. The purpose of this feature is to prevent damage occurring to any part of the system if for any reason the feeder cable 11 becomes earthed or shortcircuited at any point, or alternatively in the eventthatthe number of solenoid operated devices connected to the system and which may be energised simultaneously require a total amount of electrical energy which exceeds the capability of power supply 28, interface electronics 37 or cable 11. The detection of such described short circuit, or low impedance, could be caused to activate a display device, or lamp, on the front panel display system 38.Such message could read "Line Faultoverload" or similar.

A further feature of this invention is that, in similar manner to the previosly described feature, output currents can at all times be monitored such that an indication may be given when the output current in line 11 becomes abnormally low, such indication suggestion that the feeder wire 11 could have, at some point, become open circuited, or that a solenoid operated device has failed or become disconnected. An advantage of the above-described last two features is that by study of presented data on the display means 38 (which has been derived from line current monitoring at all times), an accurate assessment with regard to geographical location of a line or solenoid fault may be made.By way of example, display means 38, which may incorporate a video c.r.t., could be arranged to present messages such as: "Fl -2: Current not sensed - suspect cable break" or "G7-2: device switched but over-current sensed suspect faulty" and similar.

In one or more embodiments of the present invention, referring again to Figure 3, much of the contents of the main control panel P-Q-R-S-P will consist of printed wiring board type of assemblies common with many, or most, electroncially based systems and will contain no mechanically moving parts. Similar construction will apply to items 1,2,3 and 5 contained within the solenoid devices, an example of which is drawn in Figure 3 within the area A-B-C-D-A.

An advantage of such a constructional method enables a further feature of the invention, or embodiments of it, which is that all of the electronics circuitry may be completely encapsulated in some form of resin-based compound, or alternatively may be completely immersed in a form of varnish or otherinsulative material in order that damage and malfunction due to dampness or wet surroundings may be avoided.In one or more embodiments of the present invention there will be a requirement: for the operating controls and keyboard to be constructed in such a manner that there are no protruding parts such as switch knobs or toggle levers, and further to be constructed in such a mannerthatthe ingress of dust, dirt, and moisture to internal parts of the control panel is avoided, and a further requirement that any engraving or legend, or printing which forms a permanent feature of front panel design shall not be easily erasable or removable, or disintegratable in damp environments. Afurther requirement may be that cleaning of the front panel be possible to achieve in an easy manner with no protrusions or dirt-collecting crevices or indentations, nor with the inclusion of easily broken protrusions.

A feature of one or more embodiments of this present invention is designed to comply with the all of the above requirements in respect of operating controls and its principle will now be described with reference to Figure 4, which illustrates part of a typical operating panel of the type to be hereinunder described. The assembly is constucted upon a flat insulating card of glass fibre or of resin bonded paper which carries electrically conductive paths, or tracks, attached to it and what is known commonly as a printed wiring board.

Referring nowto Figure 4, the base printed circuit board 1 carries "printed wiring" associated with the control panel function on the top side of the board and may also carry associated conductive tracking 2 on the underside together with link pins or electroplating or some other conductive filling 3 situated in holes through the board 1 in order to electrically join tracking on both sides of board 1 where necessary.

An essential part of the printed wiring is that whereverthe geographical position of a switch element occurs, then two separate conductive tracks 4, 5 shall be placed on the top side of the board in close proximity, but not in contact, with each other. The "top" side of the board 1 is laminated with a sheet of insulating material 6 into which holes have been cut wherever the geographical position of a switching element is to occur. Indicator lamps, display devices and L.E.D's 7 may also be attached to the printed wiring board 1 in such manner that the illuminating surface of each such device protrudes through board 1 and preferably through spacer sheet 6 although in the case of a display device the illuminating surface of a display device 7 could alternatively protrude through board 1 only if spacer 7 were to be of suitable transparent material.The laminated assembly consisting of board 1 and spacer 6 is now further laminated with a layer of polyester or similar flexible material 8 onto which printed patterns and printed information has been deposited onto the underside to be attached to the spacer layer 6, in such manner so that the printed patterns and legends are sandwiched between the flexible material 8 and the spacer 6. Parts of the printed material could form, by way of example and referring again to Figure 4, base colour 9; alternative clear or translucent colour areas 10 through which display devices 7 may be easily viewed via the transparent layer 8; coloured rectangles or other shapes whenever the geographical location of a switch layer is to occur 11. Printed legend, characters and symbols of identification 12.The reverse (or underside) of the printed material is further laminated with areas of conductive foil, or over printed with conductive ink 13 which is normally maintained at a small distance from conductive tracks 4 and 5 by means of spacer layer 6. When a switching action is required, the polyester membrane 8 is pressed manually at a point where the appropriate printed legend 11,12 is located above suitable hole, or cutout, in spacer layer 6. This action causes the membrane 8 to distort, or deflect such that conductive film, or layer 13 contacts areas 4 and 5, so causing them to become electrically shorted, or linked. When manual pressure is removed from the membrane 8, the latter returns to its original undistorted position thus terminating the switching together of contacts4 and 5 via conductive area 13.

In the foregoing example a control panel, or operating means, has been provided which satisfactorily complies with previously mentioned requirements with respect to the prevention of ingress of dirt, dampness and foreign matter; and with respect to the avoidance of protrusions, and with respect of ease of cleaning without the erosion of printed legend and characters.

It will be appreciated that various further alterations and modifications may be made to the system as described above without departing from the scope of the invention. In one advantageous arrangement, not shown in the drawing, the solenoid powervoltage supplied to the signal bus 11 of Figure 3 may comprise the normal a.c. mains power supply, which is modulated by the interface device 37 under the influence of the encoding device 36, in order to provide binary address signals. For example, suppression of a positive going half cycle of the a.c. mains waveform may be utilised to represent one binary value, e.g. binary "1", whereas suppresion of a negative going half cycle of the waveform may be utilised to represent the other binary value, e.g. binary "0". Preferably, in order to avoid false recognition of a binary address signal due to corruption of the data signal, each binary address signal intended to actuate a corresponding solenoid valve is transmitted a predetermined number, for example 10, times, and the code-reading circuit of each solenoid-operated watering device is required to recognise a plurality of identical consecutive address signals, for example 4 signals, before causing actuation of the solenoid valve.

Claims (13)

1. An electronically controlled irrigation system, comprising a subterranean water supply conduit provided with a plurality of distributor outlets arranged at predetermined locations spaced apart over an area of ground to be watered, each said outlet being coupled to a corresponding irrigation outlet device including an electrically actuatable solenoid valve for controlling the flow of water through said outlet device, and a control system for controlling the operation of all of said solenoid valves according to a predetermined watering control programme wherein said valves are actuated in timed relation to one another, either individually or in groups, said control system comprising a central processor unit and a plurality of slave units all connected to said central processor unit by means of a common signal bus and each individually associated with a corres ponding solenoid valve, the arrangement being such that during the said control programme the said central processor unit transmits onto said common signal bus a plurality of control commands each in the form of a coded digital signal representing an address code of a corresponding one or more of said slave units, and each slave unit incorporating means for recognising the digital signal corresponding to its own individual address and responding thereto to actuate the corresponding solenoid valve associated therewith.

2. A system as claimed in Claim 1, wherein all of said slave units and said solenoid valves are connected in parallel to a common subterranean ring main power supply forming the said signal bus and connected to a source of solenoid power voltage by way of an interface device controlled by said central processor unit and arranged to superimpose the said digital address signals upon the solenoid power voltage, the arrangement further being such that each solenoid is enabled to respond to its supply voltage only upon recognition of the corresponding digital address signal by its associated slave unit.

3. A system as claimed in Claim 2, wherein each solenoid valve is associated with latching means for maintaining energisation of the solenoid after the initial response of the associated slave unit, and the central processor unit is arranged to close all solenoid valves at the termination of each watering step in the control programme by causing said interface device temporarily to interrupt solenoid voltage applied to said ring main.

4. A system as claimed in any one of Claims 1 - 3, wherein said central processor unit comprises a microprocessor system associated with a visual display unit (V.D.U.) arranged to display information relating to the status of the watering control programme being effected.

5. A system as claimed in Claim 4, wherein said microprocessor system is associated with a manual keyboard enabling optional selection of a desired control programme sequence, and/or interrogation of the central processor unit.

6. A system as claimed in Claim 4 or 5, wherein said microprocessor is connected to one or more sensors for detecting control parameters governing the watering control programme.

7. A system as claimed in Claim 6, wherein the or one of the sensors comprises means for monitoring the water supply connected to said conduit.

8. A system as claimed in Claim 6 or 7, wherein the or one of the sensors comprises means for detecting rainfall in the area to be irrigated.

9. A system as claimed in Claim 2, wherein said source of power supply voltage is an a.c. mains voltage, and the said interface device is arranged to modulate the said a.c. mains waveform to provide binary encoded address signals.

10. A system as claimed in Claim 9, wherein the arrangement is such that suppression of a positive ha If cycle of the mains waveform is utilised to represent one binary value and suppression of a negative half cycle of the mains a.c. waveform is utilised to represent the other binary value.

11. A system as claimed in Claim 9 or 10, wherein the arrangement is such that each said binary encoded address signal is transmitted consecutively a first predetermined number of times, and each said slave unit is required to recognise a second predetermined number of consecutive address signals before causing actuation of its associated solenoid valve, said second predetermined number being less than the first.

12. Asystem as claimed in Claim 11, wherein said second predetermined number is at least 4 and said first is at least 10.

13. An electronically controlled irrigation system substantially as described herein with reference to Figures 2 - 4 of the accompanying drawings.