WO2010143016A1

WO2010143016A1 - Control apparatus for irrigation systems

Info

Publication number: WO2010143016A1
Application number: PCT/IB2009/052452
Authority: WO
Inventors: Giandomenico Dorigo
Original assignee: Prato Verde Spa
Priority date: 2009-06-09
Filing date: 2009-06-09
Publication date: 2010-12-16

Abstract

A new control system for irrigation plants with optimised automatic operation comprising, in its main parts, at least one irrigation control unit (A), suitable for activating/de-activating one or more sectionalisation valves or solenoid valves and/or irrigation devices (U), and one single sensor (S) suitable for detecting the humidity in the ground, wherein the values detected (U1, U2, U3) are compared with at least one pre-set minimum humidity reference value (Ur). When the irrigation has started, the irrigation cycle is not interrupted even if said sensor (S) detects an increase in the humidity value (U2) of the ground above said pre-set minimum reference value (Ur).

Description

CONTROL APPARATUS FOR IRRIGATION SYSTEMS

DESCRIPTION

The present patent concerns control systems and circuits for irrigation plants and in particular concerns a new control system for irrigation plants. Irrigation plants for land and green areas in general are known, suitable for distributing irrigation water in a uniform manner over the entire surface in question.

Said plants generally comprise pipes and irrigators distributed over said surface in a uniform manner and furthermore generally comprise two or more valves or solenoid valves for sectionalisation of said surface, where the opening/closing of said valves is controlled by means of a control system which determines start-up of the irrigation cycles.

The irrigation systems are controlled by a control system comprising a control unit which starts or interrupts the irrigation cycles and one or more humidity sensors planted in the ground in each sector in order to detect the humidity in the ground at a certain depth in said sector.

Said control systems, comprising a control unit and at least one sensor for each valve or sector, are extremely complex for said single control unit to manage and, in order to guarantee efficient correct operation in the long term, top quality sensors have to be used, thus entailing very high costs.

Said sensors determine the humidity value in the ground to be irrigated and said value detected is compared with a pre-set minimum reference value, for example 25% humidity.

When the value detected is below said minimum value, it means that the ground is dry and therefore requires irrigation. On the contrary, when the value detected is above the reference value, the ground is moist and the irrigation is therefore immediately interrupted. In general in the known systems the irrigation cycles are programmed to be started at certain times of the day and at regular intervals, for example every

24 hours, always at the same time.

In the known systems, the irrigation cycle can be of the type with split cycles, supplying water in a certain sequence and independently from one sector to another, according to the different and specific irrigation requirements of each sector.

A drawback of the known systems consists in the fact that if one of the sensors detects a humidity value greater than the reference value, the irrigation is suspended at any time in the cycle, even if the ground has not been sufficiently irrigated in all the sectors, as occurs especially in the case of uneven ground, ground with variations in level or zones that are more or less sheltered than others, where there is a different rainwater influx, etc.

In said case, in fact, the irrigation could be suspended even though it would be expedient to continue it, therefore running the risk of ruining entire areas of the ground to be irrigated due to a poor or insufficient water supply.

Furthermore, interruption of the irrigation, even momentary, for example in one single sector, can cause damage to the pumps, which in the meantime continue to operate, therefore requiring maintenance and involving related costs.

Control systems where the humidity values detected by one or more probes or sensors are compared with a lower reference value and an upper reference value are also known.

When the value detected is below said lower reference value, the control unit switches on the irrigation plant and starts the irrigation cycle, which is interrupted when one or more probes detect that said upper reference value has been reached. The object of said type of system is to minimise water consumption, aiming to maintain the humidity value detected within a certain range.

To remedy all the above-mentioned drawbacks, a new type of control system for irrigation plants has been designed and produced with optimised automatic operation.

The main aim of the present invention is to automatically control operation of the irrigation control unit by one single sensor for detection of the ground humidity level.

A further object of the present invention is to optimise water consumption, according to the ground humidity value, while always guaranteeing a sufficient water supply throughout the entire surface to be irrigated.

A further object is to drastically reduce plant costs, since one single humidity sensor is used, furthermore simplifying the management of said plant. A further advantage of the present invention is to guarantee correct efficient operation in the long term.

These and other objects, direct and complementary, are achieved by the new control system for irrigation plants with optimised automatic operation comprising, in its main parts, at least one irrigation control unit, suitable for activating/de-activating one or more sectionalisation valves or solenoid valves and/or irrigation devices, and one single sensor suitable for detecting the humidity in the ground, where the values detected are compared with at least one pre-set minimum humidity reference value.

If, prior to the time programmed for the start-up of an irrigation cycle, the value detected is below said reference value, said control unit switches on the irrigation cycle, i.e. the nearest programmed irrigation cycle.

If, on the contrary, prior to the time programmed for the start-up of an irrigation cycle, said sensor detects a humidity value greater than said reference value, the control unit does not start the nearest irrigation cycle, i.e. it does not start irrigation at least until the time programmed for start-up of the next irrigation cycle. When the irrigation has started, the irrigation cycle is not interrupted even if said sensor detects an increase in the humidity value of the ground above said pre-set minimum reference value.

Therefore, for example, even in the case of rain which increases the humidity of the ground, the irrigation cycle, once started, is not interrupted, independently of the subsequent readings of said sensor.

It is also possible to suspend or ignore the sensor reading until the programmed end of the cycle.

In the preferred solution, once the irrigation cycle has started, said sensor is by-passed or the values detected by the sensor are ignored for a set time interval T and reconsidered only after the end of said time interval T.

In this way minimum irrigation of the ground is always guaranteed, independently of the humidity conditions reached in the meantime and independently of the values detected by the sensor.

For example, once the irrigation cycle has started, said humidity detection sensor can be de-activated or disconnected for a set time, for example until the cycle has been completed.

Said new system comprises an electric or electronic circuit which connects said control unit, said sensor and said one or more valves or solenoid valves or devices for irrigation in general. Said circuit can also comprise at least one delay circuit suitable for excluding said sensor after start-up of the irrigation, so that said irrigation cycle is completed in full, independently of the humidity value of the ground.

This is particularly effective if the irrigation cycle comprises one or more split cycles since, if the sensor detects a humidity value in the ground below said reference value, it prevents the cycle re-starting from a random sector or area instead of from the sector or area that must be treated first.

Furthermore the circuit preferably also comprises at least one timer suitable for excluding said sensor for a certain time so that the irrigation programme is completed, for example in the case of split cycles.

Said sensor can be excluded for 12 hours, for example, and during said interval any split cycles of the irrigation cycle will be completed.

The characteristics of the new system will be better clarified by the following description with reference to the drawings, attached by way of non-limiting example.

Figure 1 shows a diagram of a possible embodiment of the circuit (C) according to a first solution.

Figure 2 shows a diagram of another possible embodiment of the circuit (C) also comprising a delay circuit (Cr).

Figure 3 shows a block diagram of a further possible embodiment of the circuit (C) also comprising a timer (Ct). The new control system for irrigation plants comprises at least one irrigation control unit (A) suitable for activating/de-activating one or more sectionalisation valves or solenoid valves and/or irrigation devices (U) of the plant, one single sensor (S) suitable for detecting the humidity in the ground, where the values detected are compared with at least one minimum humidity reference value, and at least one electric or electronic circuit (C) for connection of said control unit (A), said sensor (S) and said one or more solenoid valves or irrigation devices (U). Said circuit (C) comprises at least one output contact (Sl) of said sensor (S), said contact (Sl) being closed (1) when said sensor (S) detects a humidity value below said reference value, thus powering said solenoid valves (U), and open (2) when said sensor (S) detects a humidity value above said reference value, preventing powering of said solenoid valves (U).

Said circuit (C) also comprises at least one relay (R) suitable for being crossed by current when said output contact (Sl) closes (1), where the excitation of said relay (R) causes the closure (4) of at least one second contact (S2), initially open (3). Said second contact (S2) by-passes said first output contact (Sl) of said sensor (S), so that if said output contact (Sl) re-opens, as happens if it detects a humidity value above said reference value, the power supply to said solenoid valves (U) is not interrupted. According to a possible further solution, shown in figure 2, said circuit (C) comprises at least one delay circuit (Cr) suitable for excluding said sensor

(S) throughout the irrigation cycle.

According to the preferred solution, shown in figure 3, said circuit (C) comprises at least one timer (Ct) suitable for excluding said humidity sensor (S) for a pre-set time after the beginning of said irrigation cycle. Figures 4a and 4b contain diagrams illustrating operation of the new control system for irrigation plants during an irrigation cycle. As shown in figure 4a, if, before the time programmed for the start-up (I) of an irrigation cycle, the humidity value detected (Ul) is below a reference value (Ur), said control unit (A) switches on the irrigation cycle, i.e. the nearest programmed irrigation cycle.

When the irrigation has started, the irrigation cycle continues to its normal conclusion (E) and is not interrupted even if said sensor detects a humidity value (U2) in the ground above said reference value (Ur). On the contrary, as schematised in figure 4b, if, before the time programmed for start-up (I) of an irrigation cycle, said sensor (S) detects a humidity value (IJl) above said reference value (Ur), the control unit (A) does not start the nearest irrigation cycle, i.e. it does not determine start-up of the irrigation at least until the time programmed for start-up of the next irrigation cycle (F). Therefore, irrigation does not start before the subsequent irrigation cycle even if the sensor (S) detects one or more values (U2, U3) below said reference value (Ur). Therefore with reference to the preceding description and the attached drawings the following claims are made.

Claims

1. Control system for irrigation plants, comprising at least one irrigation control unit (A) suitable for activating/de-activating one or more sectionalisation valves or solenoid valves and/or irrigation devices (U) of the plant, at least one sensor (S) suitable for detecting the humidity in the ground, where the values detected are compared with at least one minimum humidity reference value, and at least one electric or electronic circuit (C) for connection of said control unit (A), said sensor (S) and said one or more solenoid valves (U), characterised in that if one or more of said values detected by said sensor (S) are below said reference value, said control unit

(A) starts an irrigation cycle and switches on said solenoid valves (U), wherein, after the start of said irrigation cycle, said sensor (S) is by-passed or excluded from said circuit (C) for at least a set time interval T, so that the cycle continues for said set time T, independently of the humidity values of the ground subsequently detected by said sensor (S).

2. Control system for irrigation plants according to claim I₅ characterised in that, with irrigation cycles with start programmed at preset times and intervals, if one or more of said values detected (Ul) by said sensor (S) are below said reference value (Ur), said control unit (A) permits start-up of the nearest irrigation cycle, as programmed at pre-set times and intervals.

3. Control system for irrigation plants according to claims I₅ 2, characterised in that if said sensor (S) detects at least one humidity value (Ul) of the ground greater than said reference value (Ur), said control unit (A) does not start the nearest irrigation cycle, as programmed at pre-set times and intervals.

4, Control system for irrigation plants according to claims 1, 2, 3, characterised in that it comprises one single sensor (S).

5, Control system for irrigation plants according to claims 1, 2, characterised in that, after start-up of said irrigation cycle, said sensor (S) is by-passed or excluded from said circuit (C) until conclusion of the cycle.

6, Control system for irrigation plants according to the preceding claims, characterised in that said circuit (C) comprises: at least one output contact (Sl) for said sensor (S), said contact (Sl) being closed when said sensor (S) detects a humidity value below said reference value, thus powering said solenoid valves (U), and open when said sensor (S) detects a humidity value higher than said reference value, preventing powering of said solenoid valves (U);

• at least one relay (R) suitable for being crossed by current when said output contact (Sl) closes, and wherein the excitation of said relay (R) causes the closure of at least one second contact (S2) which by-passes said first output contact (Sl) so that, if said output contact (Sl) reopens, the power supply to said solenoid valves (U) is not interrupted for said set time interval T or until the conclusion of the irrigation cycle.

7, Control system for irrigation plants according to the preceding claims, characterised in that said circuit (C) comprises at least one delay circuit (Cr) suitable for by-passing or excluding said sensor (S) throughout the irrigation cycle. 8. Control system for irrigation plants according to the preceding claims, characterised in that said circuit (C) comprises at least one timer (Ct) suitable for by-passing or excluding said sensor (S) for said set time interval T after the beginning of said irrigation cycle.