FR2509127A1 - Automatic control system for irrigation installation - contains integrator at sun sensor output to control flow valve when particular energy level received - Google Patents

Abstract

A solar radiation sensor comprises a silicon chip behind a diffusion plate protected by a transparent dome. The radiation entering this assembly is a function of the cosine of the angle between the vertical and the direction of the sun. The sensor output passes through an optical coupler to an integrator where a control circuit acting on frequency dividers provide a signal equal to the radiation received per square metre. The integrator output drives a control circuit for a valve in the pipe leading to the field to be irrigated. The pipe is supplied with water at high pressure from a pump and a flowmeter measures the quantity of water flowing. The flowmeter provides a feedback signal for the integrator control circuit to turn off the water supply when the required quantity has been delivered.

Description

Irrigation installation.

The invention relates generally to computer-controlled irrigation installations, and in particular such installations which rely on sunshine and atmospheric conditions to control irrigation.

Many irrigation facilities are known and used today. Several of these installations either allow the circulation of water continuously as long as water is available, or are controlled manually by opening valves and allow the water to flow on the ground. These facilities do not supply water according to crop needs, and sometimes this results in excess watering, and other times a lack of water.

Recently designed installations use complex and sophisticated detectors and controls to control characteristics such as humidity in plants, in the soil or in the air, and the amount of sunlight hitting plants. These factors are then combined with other factors to provide a signal to start up an irrigation installation, the supply of water and nutritious products to the plants being controlled. The present installation is designed to provide results comparable to those obtained by complex, sophisticated and expensive installations, without having the high cost thereof. The installation according to the invention is very particularly useful in a desert zone or in an environment provided with fully controlled watering, that is to say in greenhouses.

 It has been shown experimentally that the main factor in the water consumption of a plant is the amount of solar radiation reaching the plant over a given time. The amount of solar radiation reaching the plant is therefore a main factor when it comes to determining how much water is required by the plant at any given time. In addition, the temperature of the environment in which the plant grows acts on the amount of water required by the latter. For example, on a day when the temperature is very high, but there is not a large amount of solar radiation, plants may need more water than would seem necessary considering only the amount of radiation Another factor that is best to take into account is the amount of water supplied to plants by rainfall. In other words, when it rains, the plants need less irrigation than what would seem necessary considering only the amount of solar radiation.

Irrigation systems controlled according to the amount of radiation have been proposed in the past. However, these facilities have not proven satisfactory.

They were either too complicated and unsafe, or insufficiently sensitive to the needs of the plants to carry out the adequate control of the irrigation installation under controlled or pseudo-controlled conditions.

An object of the invention is, therefore, to provide new and improved solar control irrigation systems, in which the disadvantages mentioned above are substantially reduced or eliminated.

Another object of the invention is to provide an improved computer-controlled irrigation installation which is based, in addition to sunshine, on the atmospheric temperature and the amount of rain to control the irrigation flow rate and its duration.

These aims are achieved by the installation according to the invention which is characterized in that it comprises: reception means capable of supplying a first signal varying digitally or digitally as a function of the solar radiation striking said receiving means; integration means providing an integrated signal when a predetermined value is reached by the integrated value over time of said signal; control means causing the start of operation of the installation and sensitive to said integrated signal; and means sensitive to a specific condition to stop the operation of the installation.

The invention further provides, in one embodiment, an irrigation installation characterized in that it comprises: receiving means providing a digital or digital output signal yes varies as a function of the solar radiation striking the receiving means; temperature detector means providing a digital or digital output signal which varies as a function of the temperature in the area of the detector; integration means supplying a signal integrated on reaching a predetermined value by the integral over the time of the radiation; temperature compensation means for adjusting the integrated signal; control means sensitive to the signal to start the operation of the installation, and means sensitive to a determined condition to stop the operation of the installation.

 The invention also provides, in one embodiment, an irrigation installation which is characterized in that it also comprises rain detector means providing a digital output signal which varies according to the amount of rain a and the rain compensation means sensitive to the amount of rain to adjust the integrated signal.

When the irrigation liquid passes through the irrigation pipes and through the filters which are arranged in these pipes, mud and other undesirable materials accumulate on the filters over time. It is therefore desirable to have. easy ways to clean the filters without the need to dismantle the entire installation. An embodiment of the invention is therefore equipped with means which automatically clean the filters against the current.

The invention therefore provides an embodiment of an irrigation installation which is characterized in that it comprises integration means providing an integrated signal, control means sensitive to said signal to cause the start of operation of the installation, measuring means sensitive to the passage of a desired quantity of water and supplying a digital output signal to the integration means, and counter-current cleaning means operating in response to a signal coming from the control to clean the irrigation system.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawing, in which Figure 1 is a block diagram showing an irrigation installation controlled by solar radiation, according to.l 'invention; FIG. 2 is a diagram giving other indications on the operation of the control blocks indicated in FIG. 1 FIG. 3 is a schematic representation of a preferred embodiment of the irrigation installation according to the invention, FIG. 4 schematically shows an alternative embodiment of a detector according to the invention; and FIG. 5 shows a detail of the backwashing means according to the invention.

The solar irrigation installation 11 shown in FIG. 1 comprises an assembly 12 for receiving radiation which provides a digitally varying signal. In a form of realization. preferred, the signal varies in frequency depending on the intensity of the radiation striking the assembly. The signal is transmitted by a conductor 13 to interface and integration devices represented globally by block 14. The output of the integration device from block 14 is a digital signal which is led by a conductor 16 to the control circuit. 17 which controls the valve 18 used to allow the irrigation liquid to circulate in the conduit 19 through a measuring device such as a flow meter 21, thanks to an electrical output such as an electrical contact closure , supplied to an irrigation installation, generally designated by the reference 22.

The receiving assembly 12 comprises a silicon chip 26 mounted inside a receptacle in such a way that the intensity of the radiation is a function of the cosine of the angle included between the direction of the sun and the vertical .

The input R. of radiation equal to the value Ro present when the sun is directly vertical, multiplied by the cosine of the angle included between the direction of the sun and the vertical. So, for example, when the sun is directly above the receiver, the maximum radiation is received. The receiving chip 26 is located behind a diffusion plate 27 which diffuses the rays striking it. The diffusion plate 27 is protected by a transparent dome 28.

The chip provides different frequencies depending on the impact that hits it. The chip is sensitive to light in the spectrum that extends from infrared to ultraviolet or, more quantitatively, from 350 to 1200 nanometers, with the peak sensitivity at approximately 800 nanometers.

In a preferred embodiment, the output is equal to one pulse per second for each kilojoule per square meter per second of global incident solar radiation.

Means are provided for coupling an integrated circuit to the receiver. It is more particularly preferred that there is complete isolation between the reception assembly and the circuit which follows it. This is ensured in a preferred embodiment by the coupling means used between the reception assembly 12 and the integration circuit 14.

The coupling means 29 comprise an optical coupler 29 placed between the conductors 13 and 15.

The integration circuit 14 continuously adds the response of the receiver over a period of time, and thus provides a signal which is dimensionally equivalent to kilojoules per square meter. The integration circuit is adjusted for the reception of a certain number of pulses equivalent to a certain number of kilojoules per square meter of global incident solar radiation, after which it provides a control signal at 16. The signal control at 16 works with the control device 17 so as to operate an outlet device such as the valve 18 in the conduit 19 leading to the field to be irrigated from a source of irrigation water such as a pump. Thus, for example, the duct 19 is connected to a source of water under high pressure, and when the valve 18 is open, the water circulates towards the irrigation installation indicated by 22.

The flow of water circulating in the irrigation installation is measured by the flow meter 21. This flow meter sends a signal pulse back to the control circuit 17. The control circuit is adjusted for a certain amount of water by control setting 31, for example. the set quantity is read in display 32. When the quantity of water measured by the flow meter 21 is equal to the adjusted quantity as indicated in reader 32, the valve is then deactivated and closed, stopping circulation d water to the irrigation facility.

At the time of operation of the valve 18, the integration circuit is reset to zero, so that it can continue to operate for the time that the control circuit keeps the valve 18 open.

The circuit shown in Figure 2 shows in greater detail what is happening in blocks 14 and 17 in Figure 1.

In FIG. 2, for example, the output of the photocoupler is coupled to the integration circuit 14 which comprises a multiplicity of frequency dividers. Dividers provide the output signal based on the required or set number of kilojoules per square meter.

The integrator 14 shown comprises three frequency dividers, the first frequency divider 36 being for example a preset divider circuit. The output of receiver 12, in a preferred embodiment, is about 100 kilohertz, and the first divider network is set so as to have an output over a range such that the dividers can provide one cycle per second output. In a preferred embodiment, the first divider circuit is preset to divide by 16.

The second frequency divider 37, which is associated with the output of the first frequency divider by the conductor 38 is an adjustable frequency divider which is able to divide by 1 or 10, 100 or 1000.

The third frequency divider 39, which is connected to the output of the second frequency divider by the conductor 41, is also of the adjustable type and it divides by a value between 1 and 99. The action of the command 23 on the integrator thus adjusts the two frequency dividers 37 and 39 so as to obtain the desired number of kilojoules per square meter. The output of the frequency divider 39 is supplied by the conductor 16 to the control circuit 17. At the input of the control circuit, a clock 42 is provided. The clock considers that there is sufficient time between production of the output signal by the frequency divider 39 and the reset signal for the operation of a counter 43 provided in the control circuit. The output of the clock 42 is connected by the conductor 44 to the input of the counter 43 which counts the number of irrigations provided by the installation.

At the same time, the output of the clock 42 also excites the relay K1 which closes a contact. This contact excites the part of the circuit 17 controlling the valve which then opens the solenoid valve 18 by switching on the irrigation installation by sending a valve activation signal by the conductor 31.

The flow meter 21 measures the quantity of water passing through the irrigation installation and it transmits to the control circuit 17, by the conductor 32, a number of pulses corresponding to the water flow.

When the number of pulses emitted by the flow meter is equal to the number preset at the meter 43, the solenoid valve closes and irrigation stops until another signal is received from the control unit 17 .

Another characteristic of the invention is that the operation of an irrigation installation is continuously controlled over long periods of time. The installation can cause the supply of irrigation water either for short periods1 or for long periods. The installation can also keep the water supply cut off for long periods of time.

The installation can thus spray plants for cooling purposes at intervals of a few seconds, but it can also connect the water at intervals of a few weeks. Thus, in a preferred embodiment, for a maximum incident solar radiation flux density of 1 kilowatt per square meter, the variation in the number of seconds during which the installation is kept out of service or in service is from 1 to 99,000 seconds.

FIG. 3 represents an irrigation installation in a preferred embodiment of the invention, placed in a cultivation area generally designated by 102. A primary irrigation conduit 104 coming from a source of irrigation water such that a pump is connected to a multiplicity of secondary irrigation conduits, sprinklers, drip distributors or other means 108 distributors of irrigation liquid which are aligned in the rows of crops. The primary conduit 104 is equipped with an inlet valve 103. The secondary conduits 108 are equipped with valves 109 which are electrically controlled to be opened and closed on demand to irrigate the growing area. The cultivation zone 102 may include fields or greenhouses.

The control installation comprises an assembly 110 for receiving solar radiation, similar to that which is represented in FIG. 1, which provides a digitally varying signal. Preferably, the frequency of the signal varies as a function of the intensity of the solar radiation striking the assembly.

The signal is transmitted by a conductor 111 to the interface and integration apparatus 120.

A temperature detection apparatus 112 is further provided, and it provides a digitally varying signal. Preferably, the frequency of the signal varies as a function of the temperature at the location of the detection device 112. The signal is transmitted by the conductor 113 to the interface and integration apparatus 120. The i20 integration device includes temperature compensation means which regulate the output signal as a function of the temperature.

The output of the integration apparatus 120 is a digital signal which is transmitted by the conductor 123 to the control circuit 124. The integration carried out by the apparatus 120 follows an empirical formula which is a function of the two main variables, the solar radiation and temperature. The control circuit 124 controls the valves 109 to allow the irrigation liquid to circulate in the primary conduit 104 passing through a measuring device such as a flow meter 126 with electrical output such as an electrical contact closure, for finally reach the secondary conduit 108.

A rain sensor apparatus 114 is further provided which provides a digital output signal which varies depending on the amount of rain. The signal is transmitted by the conductor 113 to the interface and integration apparatus 120.

In one embodiment of the invention, the integration device 120 further comprises rain compensating means which regulate the output signal as a function of the amount of rain.

An alternative embodiment of a rain detector device is shown in Figure 3. The device of Figure 3 adds the water received by rain to the water supplied through the flow meter 21. More specifically, a detector Quantitative rainfall 20 is provided to provide the driver 35 with a signal which is a function of the amount of rain. The output of the flow meter 21 and the output of the detector 20 are both associated with an addition circuit 25 by respective conductors 30 and 35. The quantity of water is then supplied to the conductor 32 for the operation of the comparator circuit.

Thus, for example, if the amount of rain is greater than the predetermined amount of water, the valve 18 remains closed.

If the amount of rain is less than the preset amount, the valve 18 is opened and the amount of water supplied by the rain is completed.

The receiver assembly 110 includes a photodiode and a microprocessor which provides different frequencies depending on the solar radiation striking it.

The temperature detector apparatus 112 comprises a thermistor or any other suitable temperature detection device, and a microprocessor provided with a calibration circuit and which supplies different frequencies as a function of the temperature.

The rain sensor apparatus 114 includes a quantitative rain sensor which provides a signal which is a function of the amount of rain.

The integration apparatus 120 continuously performs the sum of the response of the receiver assembly 110 over a determined duration, and it thus provides a signal which is dimensionally equivalent to kilojoules per square meter. This output signal is then modified to take into account the signal from the temperature detector device 112 and, if desired, the signal from the rain detector device 114. The integration apparatus 120 preferably includes a multiplicity of frequency dividers to provide the output signal in response to the required or set number of kilojoules per square meter, as described in connection with Figure 1.

The final output signal from the integration apparatus 120 acts through the control circuit 124 so as to operate the irrigation installation.

The conductor 125 operates to open and close the valves 109 in response to signals from the control circuit 124. The control circuit 124 further includes a comparator circuit that compares. the desired and preset quantity of irrigation liquid to the actual quantity of liquid measured by the measuring device 126. When the two quantities are equal, the control circuit 124 sends a signal to close the valves 109. In the alternative embodiment shown in Figure 4, the output of the rain sensor device enters directly into the comparator circuit of the control circuit 124. (rather than passing through the integration device 120). The amount of rain is thus added to the amount of water that has already passed the flow meter, and this total is compared to the desired preset amount.

FIG. 5 represents an embodiment of the installation for cleaning the filters against the current according to the invention. The secondary conduit 108 is equipped with a bypass 150 which starts from the conduit 108 on one side of the filter 116 and which joins this conduit on the other side of the filter. The bypass 150 is provided, at each end, with valves 152, such as three-way valves, to allow the isolation of the bypass 150 when the installation is not descaled by counter current. The secondary conduit 108 is also provided with an outlet 154 with associated valve 156. When a certain predetermined quantity of irrigation liquid has circulated in the irrigation installation, or when the control circuit 124 receives a signal indicating that the water pressure in the conduit 108 has dropped by a certain value, I control circuit 124 sends a signal by the conductor 144, to start the backwashing. The valves 152 and 156 open to allow the liquid to enter the bypass 150 from the primary conduit 104, to circulate in the conduit 108 and in the filter 116 in the direction opposite to the flow during irrigation ( as indicated by the arrows), and to escape via exit 154. When the backwashing is finished, the control circuit 124 sends a signal to close the valves 152 and 156, thus isolating the bypass 150 prior to continuing irrigation.

 The installation provided by the invention thus allows exact and economical control of the irrigation installation.

The receiver 28 provides a cosine function in response to the solar radiation striking it. The coupling of the solar radiation receiver to the rest of the circuit is carried out without charging the receiver. The coupling shown is carried out by a photocoupler of the type supplied by the Motorola Company (MOC lot0). The integration circuit dividers also allow the integration of the digital output of the receiver to be controlled. The fixed divider is a 4040 unit available on the market. The adjustable dividers and the integrated circuits are units 4018. The clock circuit of the control circuit 17 is a circuit 555. The counter 43 is of the electromagnetic type.

Claims (11)

Claims. 1. Irrigation installation controlled by solar radiation, characterized in that it comprises receiving means (12) supplying a digital output signal varying as a function of the solar radiation striking said receiving means integrating means (14) providing an integral signal when the sum over time of said radiation reaches a preset value of the control means (17) causing the start of operation of the installation in response to said signal; and means for stopping the operation of said installation in response to a determined condition. 2. Irrigation installation according to claim 1, characterized in that the receiving means (12) provide an output signal whose frequency varies as a function of the intensity of the solar radiation striking the receiving means. 3. Irrigation installation according to claim 2, characterized in that the receiving means (12) are designed such that the intensity of the radiation striking them is a function of the cosine of the angle included between the direction of the sun and an ortnogonal vertical on the horizon. 4. Irrigation installation according to any one of the preceding claims, characterized in that the operation of the installation begins in response to the opening of valve means (18) allowing the irrigation water to circulate in irrigation means (19), and in that the operation ceases in response to the passage of a determined quantity of water through the valve means. 5. Irrigation installation according to any one of the preceding claims, characterized in that the integration means (14) comprise at least one frequency divider network (36, 37, 39) capable of dividing the frequency of the signal supplied by the receiving means (12). 6. Irrigation installation according to any one of the preceding claims, characterized in that the control means (17) comprise a counter for the signals supplied by the integration means and delivering an electrical signal in response to a determined account. 7. Irrigation installation according to any one of claims 4 to 6, characterized in that it comprises flow measurement means (21) placed in the conduit of the irrigation installation to determine the amount of water circulating in the irrigation installation (22), and means sensitive to the circulation of a desired quantity of water to operate said valve (18) and close it. 8. Irrigation installation according to any one of claims 5 to 7, characterized in that said frequency divider is reset to zero in response to the signal opening said valve. 9. Irrigation installation, characterized in that it comprises receiving means (110) providing a digital output signal which varies as a function of the solar radiation striking the receiving means of the temperature detecting means (112) providing an output signal digital which varies according to the temperature at the location of the detector of the integration means (120) supplying an integral signal when the sum in time of the radiation reaches a predetermined value of the temperature compensation means for adjusting the signal integral control means (124) for causing the start of operation of the installation in response to the signal; and means for terminating the operation of the installation in response to a determined condition. 10. Irrigation installation according to claim 9, characterized in that it further comprises rain detector means (114) providing a digital output signal which varies according to the amount of rain, and means for compensating for rain to adjust the full signal based on the amount of rain. 11. Irrigation installation characterized in that it comprises integration means (14, 120) providing an integral signal from the control means (17, 124) causing the start of operation of the installation in response to said signal; measuring means (21, 126) providing a digital output signal to the integrating means in response to the passage of a desired amount of irrigation liquid; and backwash filter cleaning means operating in response to a signal from the control means. to clean the irrigation system.