JP2018033333A - Liquid supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide liquid supply devices that can control the fertilizer component concentration of nutrient solution.SOLUTION: A raw water supply part 12 supplies raw water w. A fertilizer supply part 13 supplies fertilizers fa and fb. A mix part 14 mixes the raw water w supplied from the raw water supply part 12, and the fertilizers fa and fb supplied from the fertilizer supply part 13 to make a nutrient solution. A first electric conductivity measuring part 40 measures the electric conductivity of the raw water w supplied by the raw water supply part 12. A second electric conductivity measuring part 61 measures the electric conductivity of the nutrient solution mixed by the mix part 14. A controller 16 controls the supply of the fertilizers fa and fb from the fertilizer supply part 13 based on the electric conductivity of the raw water w measured by the first electric conductivity measuring part 40 and the electric conductivity of the nutrient solution measured by the second electric conductivity measuring part 61.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nutrient solution supply apparatus.

  2. Description of the Related Art Conventionally, for example, in a nutrient solution supply apparatus used for nutrient cultivation of agricultural crops, raw nutrient solution is prepared by mixing raw water and fertilizer, and this nutrient solution is supplied to the culture medium of the cultivation bed.

  In such a nutrient solution feeder, it is known to perform flow rate proportional control or electrical conductivity proportional control in order to make the concentration of the fertilizer component of the nutrient solution constant. In the flow proportional control, the amount of fertilizer introduced into the raw water is controlled in proportion to the flow rate of the raw water. In addition, in the electrical conductivity proportional control, the electrical conductivity of the nutrient solution that is proportional to the fertilizer component concentration of the nutrient solution is measured by an electrical conductivity measurement unit provided on the supply outlet side of the nutrient solution, and the measured electrical conductivity is measured. The amount of fertilizer introduced into the raw water is controlled so that the conductivity becomes the target electrical conductivity.

  And in electrical conductivity proportional control, it is intended to manage the fertilizer component concentration of the actual nutrient solution by measuring the electrical conductivity of the nutrient solution, but when measuring the electrical conductivity of the nutrient solution Also, fertilizer components and ion concentrations contained in the raw water itself are measured.

  Therefore, in the electrical conductivity proportional control, when the electrical conductivity of the raw water itself is high, it may be difficult to accurately manage the fertilizer component concentration of the nutrient solution, such as decreasing the fertilizer concentration of the nutrient solution.

JP 2004-298055 A

  An object of this invention is to provide the liquid supply apparatus which can manage the fertilizer component density | concentration of a nutrient solution correctly.

  The liquid supply apparatus according to claim 1, a raw water supply unit that supplies raw water, a fertilizer supply unit that supplies fertilizer, the raw water supplied from the raw water supply unit, and the fertilizer supplied from the fertilizer supply unit. A mixing unit for preparing a nutrient solution, a first electrical conductivity measuring unit for measuring the electrical conductivity of the raw water supplied by the raw water supply unit, and an electrical conductivity of the nutrient solution mixed in the mixing unit A second electrical conductivity measuring unit for measuring the degree of electrical conductivity, an electrical conductivity of the raw water measured by the first electrical conductivity measuring unit, and an electrical conductivity of the nutrient solution measured by the second electrical conductivity measuring unit And a controller for controlling the supply of the fertilizer by the fertilizer supply unit based on the degree.

  The liquid supply apparatus according to claim 2, wherein the raw water supply unit includes a raw water supply path for supplying raw water, and the first electrical conductivity measurement unit is configured to supply the raw water supply. It is provided on the road.

  The liquid supply device according to claim 3 is the liquid supply device according to claim 1 or 2, further comprising a flow meter for measuring a flow rate of the raw water supplied by the raw water supply unit, wherein the controller includes the raw water supply unit. The supply of the fertilizer by the fertilizer supply unit is controlled in proportion to the flow rate of the raw water measured by the flow meter at the start of the supply of the raw water, and after a predetermined time has elapsed from the start of the supply of the raw water, Based on the electrical conductivity of the raw water measured by one electrical conductivity measurement unit and the electrical conductivity of the nutrient solution measured by the second electrical conductivity measurement unit, supply of the fertilizer by the fertilizer supply unit It is something to control.

  According to the liquid supply apparatus of the present invention, the fertilizer component concentration of the nutrient solution can be accurately managed.

It is a circuit diagram of a liquid supply apparatus showing an embodiment of the present invention. It is a graph which shows the relationship between electrical conductivity same as the above and a fertilizer component density | concentration.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the liquid supply device 10 is used for nutrient solution cultivation of agricultural crops, and mixes raw water w and fertilizers fa and fb to produce a nutrient solution, and this nutrient solution is used as a cultivation bed. It supplies to the culture medium.

  The liquid supply device 10 mixes the water receiving part 11 that receives the raw water w, the raw water supply part 12 that supplies the raw water w, the fertilizer supply part 13 that supplies the fertilizer fa and fb, and the raw water w and the fertilizers fa and fb. And a controller 16 for controlling the liquid supply apparatus 10.

  And the water receiving part 11 is provided with the water receiving tank 20 which stores raw | natural water w, such as well water and a tap water, for example. Raw water w is introduced into the water receiving tank 20 through the water supply valve 21, and a certain amount of raw water w is stored by the float switch 22. The water receiving tank 20 is provided with a level switch 23 for detecting the water level of the raw water w, and a drain valve 24 for discharging the raw water w in the water receiving tank 20 is connected. The raw water w stored in the water receiving tank 20 is taken out by the raw water supply unit 12.

  Note that the water receiving unit 11 may not be used, and in this case, the raw water w may be directly guided to the raw water supply unit 12.

  In addition, the raw water supply unit 12 includes a raw water supply path 27 constituted by a pipe for supplying the raw water w. The upstream side of the raw water supply path 27 is connected to the water receiving tank 20, and the downstream side is connected to the mixing unit 14. In the raw water supply path 27, water supply valve 28, a strainer 29 for removing foreign matter mixed in the raw water w, and the raw water w in the receiving tank 20 are sent to the downstream side of the raw water supply path 27 in order from the upstream side. A check valve 31 for preventing a back flow of the pump 30 and the raw water w is provided.

  A pressure tank 34 connected via a valve 33 is connected to the raw water supply path 27 downstream of the check valve 31. The pressure tank 34 absorbs an instantaneous pressure fluctuation of the raw water w in the raw water supply path 27 by, for example, an internal diaphragm. A drain valve 35 that is opened during draining is connected between the valve 33 and the pressure tank 34.

  A pressure sensor 37 that detects the pressure of the raw water w is connected to the raw water supply path 27 downstream of the connection location of the pressure tank 34 connected via the valve 33.

  A flow meter 39 for measuring the flow rate of the raw water w flowing through the raw water supply passage 27 is connected to the raw water supply passage 27 downstream of the pressure sensor 37.

  The raw water supply path 27 is provided with a first electrical conductivity measurement unit (first EC measurement unit) 40 configured by an electrical conductivity sensor (EC sensor) that measures the electrical conductivity (EC) of the raw water w. In the present embodiment, the first electrical conductivity measuring unit 40 is provided in the raw water supply path 27 on the downstream side of the water pump 30 and on the upstream side of the pressure tank 34, the pressure sensor 37, the flow meter 39, and the like. ing.

  As shown in FIG. 2, since electrical conductivity and fertilizer component concentration are in a proportional relationship (A: B), the fertilizer component concentration contained in raw water w is determined by measuring the electrical conductivity of raw water w. Can be measured. In addition, the value of the electrical conductivity measured by the first electrical conductivity measuring unit 40 includes the electrical conductivity according to the ion concentration in water in addition to the electrical conductivity value according to the fertilizer component contained in the raw water w. The value of is also included.

  The fertilizer supply unit 13 includes a plurality of fertilizer tanks 44a and 44b that store liquid fertilizers fa and fb. In these fertilizer tanks 44a and 44b, different types of fertilizers fa and fb are respectively stored in the present embodiment, but the same type of fertilizer may be stored. Further, although two fertilizer tanks 44a and 44b are shown in the present embodiment, the number is not limited to this, and may be one or three or more.

  Water is supplied into the fertilizer tanks 44a and 44b by opening the water supply valves 46a and 46b of the water supply paths 45a and 45b connected to the raw water supply path 27, respectively. The fertilizer tanks 44a and 44b are respectively provided with level sensors 47a and 47b constituted by pressure sensors for detecting the water level, and connected to drain valves 48a and 48b for draining.

  In the fertilizer tanks 44a and 44b, raw water w and raw fertilizer in solid form or liquid form, for example, are added and mixed at a predetermined ratio, and liquid fertilizers fa and fb having a predetermined fertilizer component concentration are produced. The fertilizer tanks 44a and 44b may be provided with stirrers 49a and 49b that stir the fertilizers fa and fb so that their concentrations are evenly distributed.

  Fertilizer supply paths 50a and 50b configured by piping for supplying the fertilizers fa and fb are connected to the mixing unit 14 from the fertilizer tanks 44a and 44b. The fertilizer supply channels 50a and 50b include injection pumps 51a and 51b that inject the fertilizers fa and fb in the fertilizer tanks 44a and 44b into the mixing unit 14, and check valves 52a and 52b that prevent the fertilizers fa and fb from flowing back. Is provided. As the infusion pumps 51a and 51b, for example, a metering pump such as a diaphragm pump is used. Return passages 53a and 53b are provided between the infusion pumps 51a and 51b and the check valves 52a and 52b to the fertilizer tanks 44a and 44b. 54a and 54b are provided.

  Further, the mixing unit 14 mixes the raw water w supplied from the raw water supply channel 27 and the fertilizers fa and fb supplied from the fertilizer supply channels 50a and 50b to produce a nutrient solution having a predetermined fertilizer component concentration. The mixing unit 14 includes a mixing path 58 formed by a pipe in which the raw water supply path 27 and the fertilizer supply paths 50a and 50b are connected and the raw water w and the fertilizers fa and fb are mixed.

  On the downstream side of the mixing path 58, a mixer 59 for mixing the raw water w and the fertilizers fa and fb, a filter 60 for filtering the nutrient solution, and an electric conduction sensor for measuring the electrical conductivity (EC) of the nutrient solution. A second electrical conductivity measuring unit (first EC measuring unit) 61 composed of (EC sensor) is provided.

  As shown in FIG. 2, since electrical conductivity and fertilizer component concentration are in a proportional relationship (A: B), the nutrient solution is measured by measuring the electrical conductivity of the nutrient solution with the second electrical conductivity measuring unit 61. The fertilizer component concentration can be measured. In addition, the value of the electrical conductivity measured by the second electrical conductivity measuring unit 61 includes the value of the electrical conductivity according to the mixed fertilizer fa and fb, and the electricity according to the fertilizer component contained in the raw water w. In addition to the conductivity value, an electrical conductivity value corresponding to the ion concentration in water is also included.

  Further, the liquid supply unit 15 includes a liquid supply path 63 constituted by a pipe connected to the downstream side of the mixer 59. The liquid supply path 63 is provided with a liquid supply original valve 65 constituted by an electromagnetic valve. A plurality of branched liquid supply paths 66 branched from the liquid supply path 63 are connected to the liquid supply path 63 downstream of the liquid supply source valve 65. A liquid supply valve 67 composed of an electromagnetic valve is provided in each branch liquid supply path 66.

  Since one cultivation line is used for each cultivation bed and two branch liquid supply paths 66 are used for each cultivation bed, the branch liquid supply paths 66 of a plurality of lines 68a to 68h are used corresponding to the plurality of cultivation beds. In the present embodiment, for example, eight systems 68a to 68h are shown, but any number of systems may be used.

  Further, the controller 16 controls the liquid supply apparatus 10 and inputs signals from various sensors of the liquid supply apparatus 10 to operate various drive sources of the liquid supply apparatus 10. FIG. 1 shows only the first electrical conductivity measuring unit 40, the second electrical conductivity measuring unit 61, and the flow meter 39 as various sensors connected to the controller 16, and as various driving sources. Only the water pump 30 and the injection pumps 51a and 51b are shown, and other sensors and other drive sources are not shown.

  The control by the controller 16 includes a function of controlling the supply of the fertilizers fa and fb by the fertilizer supply unit 13 so that the fertilizer component concentration of the nutrient solution to be supplied becomes a predetermined target fertilizer component concentration. . That is, based on the electrical conductivity of the raw water w measured by the first electrical conductivity measurement unit 40 and the electrical conductivity of the nutrient solution measured by the second electrical conductivity measurement unit 61, the fertilizer fa by the fertilizer supply unit 13 , Fb are controlled by electric conductivity proportional control (hereinafter referred to as EC proportional control).

  In this EC proportional control, for example, a value obtained by subtracting the electrical conductivity of the raw water w measured by the first electrical conductivity measuring unit 40 from the electrical conductivity of the nutrient solution measured by the second electrical conductivity measuring unit 61 ( Δ electric conductivity) is used as a target value, and this target value is arbitrarily set corresponding to the target component concentration. Then, when the liquid supply apparatus 10 is in operation, the fertilizer supply unit is set so that the Δ electrical conductivity obtained according to the measurement by the first electrical conductivity measurement unit 40 and the second electrical conductivity measurement unit 61 becomes the target value. 13 to control the supply of fertilizer fa, fb.

  Alternatively, a value obtained by multiplying the electrical conductivity of the raw water w measured by the first electrical conductivity measuring unit 40 by a certain coefficient (the electrical conductivity other than the fertilizer component of the raw water w, for example, the electrical conductivity corresponding to the ion concentration in water) The value (Δ conductivity) subtracted from the electrical conductivity of the nutrient solution measured by the second electrical conductivity measuring unit 61 is used as a target value, and this target value corresponds to the target component concentration. Set as desired. Then, when the liquid supply apparatus 10 is in operation, the fertilizer supply unit is set so that the Δ electrical conductivity obtained according to the measurement by the first electrical conductivity measurement unit 40 and the second electrical conductivity measurement unit 61 becomes the target value. 13 to control the supply of fertilizer fa, fb.

  Furthermore, the control by the controller 16 controls the supply of the fertilizers fa and fb by the fertilizer supply unit 13 in proportion to the flow rate of the raw water w measured by the flow meter 39 when the supply of the raw water w by the raw water supply unit 12 is started. A function of performing proportional flow control and performing EC proportional control after the elapse of a predetermined time from the start of supply of raw water w is included.

  Next, the liquid supply operation under the control of the controller 16 will be described.

  At the start of feeding the nutrient solution, driving of the water supply pump 30 of the raw water supply unit 12 is started and driving of the injection pumps 51a and 51b of the fertilizer supply unit 13 is started.

  The water supply pump 30 sucks the raw water w in the water receiving tank 20 into the raw water supply path 27, and supplies the raw water from the raw water supply path 27 toward the mixing path 58 of the mixing unit 14 and the terminal branch liquid supply path 66. The rotation speed of the water supply pump 30 is controlled so that the water supply amount or the water supply pressure of the raw water w becomes a predetermined water supply amount or water supply pressure.

  The infusion pumps 51a and 51b suck the fertilizers fa and fb in the fertilizer tanks 44a and 44b into the fertilizer supply paths 50a and 50b, and supply the fertilizers fa and fb from the fertilizer supply paths 50a and 50b to the mixing path 58 of the mixing unit 14. To do.

  In the mixing unit 14, the raw water w supplied from the raw water supply unit 12 and the fertilizers fa and fb supplied from the fertilizer supply unit 13 merge in the mixing path 58, and the raw water w and the fertilizers fa and fb are combined in the mixer 59. Mix to make nutrient solution. The nutrient solution prepared by the mixing unit 14 is supplied to the liquid supply path 63 of the liquid supply unit 15.

  In the liquid supply unit 15, the nutrient solution is distributed to the branch supply channels 66 of the respective systems 68a to 68h, and the nutrient solution is supplied from the branch supply channels 66 of the respective systems 68a to 68h to the culture medium of the cultivation bed.

  Then, the controller 16 controls the supply of the fertilizers fa and fb by the fertilizer supply unit 13 by a flow rate proportional control until a predetermined time has elapsed from the start of the supply of the raw water w by the raw water supply unit 12, and the target fertilizer component Make a nutrient solution of concentration.

  In the flow proportional control, the flow rate of the raw water w, which is the nutrient solution of the target fertilizer component concentration, is proportional to the supply amount of the fertilizers fa and fb, and is proportional to the flow rate of the raw water w measured by the flow meter 39. Then, the supply amount of the fertilizers fa and fb by the fertilizer supply unit 13 is controlled. And at the start of supply of the raw water w, as the flow rate of the raw water w increases as the rotational speed of the water pump 30 increases, the supply amount of the fertilizers fa and fb by the fertilizer supply unit 13 also increases. Make a nutrient solution of fertilizer component concentration.

  At the start of supply of raw water w by the raw water supply unit 12, the flow rate of the raw water w increases rapidly, so that control delay is likely to occur in EC proportional control. A nutrient solution having a fertilizer component concentration can be prepared.

  In addition, after a predetermined time has elapsed since the raw water supply unit 12 started supplying raw water w, the flow rate proportional control is switched to EC proportional control to control the supply of fertilizer fa and fb by the fertilizer supply unit 13, and target fertilizer components Make a nutrient solution of concentration. In addition, about the predetermined time from the supply start of the raw water w, it is set as the elapsed time counted by the timer with which the controller 16 is provided, for example, when the water pump 30 becomes a predetermined rotational speed and the water supply amount of the raw water w becomes constant. Sufficient elapsed time.

  In the EC proportional control, the electrical conductivity of the raw water w measured by the first electrical conductivity measuring unit 40 and the electrical conductivity of the nutrient solution measured by the second electrical conductivity measuring unit 61 are monitored. Based on the monitoring, the supply amounts of the fertilizers fa and fb by the fertilizer supply unit 13 are controlled so that the fertilizer component concentration of the nutrient solution to be supplied becomes a predetermined target fertilizer component concentration.

  Specifically, for example, a value obtained by subtracting the electrical conductivity of the raw water w measured by the first electrical conductivity measuring unit 40 from the electrical conductivity of the nutrient solution measured by the second electrical conductivity measuring unit 61 (Δ Electrical conductivity) is used as a target value, and this target value is arbitrarily set according to the target component concentration. Then, during the EC proportional control, the fertilizer by the fertilizer supply unit 13 is set so that the Δ electrical conductivity obtained according to the measurement by the first electrical conductivity measurement unit 40 and the second electrical conductivity measurement unit 61 becomes a target value. Controls the supply of fa and fb. By this control, it is possible to accurately adjust the fertilizer component concentration of the nutrient solution to be supplied to the target fertilizer component concentration.

  Alternatively, a value obtained by multiplying the electrical conductivity of the raw water w measured by the first electrical conductivity measuring unit 40 by a certain coefficient (the electrical conductivity other than the fertilizer component of the raw water w, for example, the electrical conductivity corresponding to the ion concentration in water) The value (Δ conductivity) subtracted from the electrical conductivity of the nutrient solution measured by the second electrical conductivity measuring unit 61 is used as a target value, and this target value corresponds to the target component concentration. Set as desired. Then, during the EC proportional control, the fertilizer by the fertilizer supply unit 13 is set so that the Δ electrical conductivity obtained according to the measurement by the first electrical conductivity measurement unit 40 and the second electrical conductivity measurement unit 61 becomes a target value. Controls the supply of fa and fb. With this control, the fertilizer component concentration in the nutrient solution can be managed with high accuracy including the fertilizer component contained in the raw water w, and the fertilizer component concentration of the nutrient solution to be fed can be accurately adjusted to the target fertilizer component concentration can do.

  In addition, if the first electrical conductivity measuring unit 40 is not provided, and the fertilizer component or ion concentration of the raw water w is changed, the second electrical conductivity measuring unit 61 may change the electrical conductivity of the nutrient solution. Since the ratio of fertilizers fa and fb to be mixed with raw water w after detection will be adjusted, control of the fertilizer component concentration of the nutrient solution is likely to be delayed, and the fertilizer component concentration of the nutrient solution is kept constant May not be possible.

  On the other hand, in the present embodiment, the first electrical conductivity measuring unit 40 is provided, and the electrical conductivity of the raw water w is measured in real time by the first electrical conductivity measuring unit 40. Even when the ion concentration fluctuates, the supply amount of the fertilizers fa and fb by the fertilizer supply unit 13 can be corrected and controlled quickly.

  According to the liquid supply apparatus 10 configured as described above, since the first electrical conductivity measuring unit 40 that measures the electrical conductivity of the raw water w supplied from the raw water supply unit 12 is provided, the first electrical conductivity is provided. Based on the electrical conductivity of the raw water w measured by the measurement unit 40 and the electrical conductivity of the nutrient solution measured by the second electrical conductivity measurement unit 61, the supply amount of the fertilizers fa and fb by the fertilizer supply unit 13 is controlled. Therefore, it is possible to accurately manage the fertilizer component concentration of the nutrient solution considering the electrical conductivity of the raw water w. In addition, it is possible to quickly follow changes in fertilizer components and ion concentrations in the raw water w, and the fertilizer component concentrations in the nutrient solution can be kept constant.

  Moreover, since the 1st electrical conductivity measurement part 40 is provided in the raw | natural water supply path 27 of the raw | natural water supply part 12, the 1st electrical conductivity measurement part 40 can measure the electrical conductivity of the raw | natural water w in real time, It is possible to quickly follow changes in fertilizer components and ion concentration, and to maintain a constant fertilizer component concentration in the nutrient solution.

  Further, the flow rate for controlling the supply amount of the fertilizers fa and fb by the fertilizer supply unit 13 in proportion to the flow rate of the raw water w measured by the flow meter 39 for a predetermined time from the start of supply of the raw water w by the raw water supply unit 12 Since proportional control is performed, there is little delay in control of the flow rate of the raw water w, and a nutrient solution having a target fertilizer component concentration can be created. Furthermore, after a predetermined time from the start of supply of the raw water w by the raw water supply unit 12, the electrical conductivity of the raw water w measured by the first electrical conductivity measurement unit 40 and the nutrient measured by the second electrical conductivity measurement unit 61 are measured. Since it switches to EC proportional control based on the electrical conductivity of the liquid, the fertilizer component concentration of the nutrient solution can be accurately adjusted to the target fertilizer component concentration.

  The first electrical conductivity measuring unit 40 is not limited to being provided in the raw water supply path 27, and may be provided in the water receiving tank 20, for example.

10 Liquid supply device
12 Raw water supply section
13 Fertilizer supply section
14 Mixing section
16 controller
27 Raw water supply channel
39 Flow meter
40 First electrical conductivity measurement unit
61 Second electrical conductivity measurement unit
fa, fb fertilizer w raw water

Claims (3)

A raw water supply section for supplying raw water;
A fertilizer supply section for supplying fertilizer;
A mixing unit that mixes the raw water supplied from the raw water supply unit and the fertilizer supplied from the fertilizer supply unit into a nutrient solution;
A first electrical conductivity measurement unit for measuring electrical conductivity of the raw water supplied by the raw water supply unit;
A second electrical conductivity measuring unit for measuring the electrical conductivity of the nutrient solution mixed in the mixing unit;
Based on the electrical conductivity of the raw water measured by the first electrical conductivity measurement unit and the electrical conductivity of the nutrient solution measured by the second electrical conductivity measurement unit, the fertilizer by the fertilizer supply unit A liquid supply device comprising: a controller for controlling supply. The raw water supply unit has a raw water supply path for supplying raw water,
The liquid supply apparatus according to claim 1, wherein the first electrical conductivity measurement unit is provided in the raw water supply path. Comprising a flow meter for measuring the flow rate of the raw water supplied by the raw water supply unit;
The controller controls the supply of the fertilizer by the fertilizer supply unit in proportion to the flow rate of the raw water measured by the flow meter at the start of supply of the raw water by the raw water supply unit, from the start of supply of the raw water After the elapse of a predetermined time, the fertilizer is based on the electric conductivity of the raw water measured by the first electric conductivity measuring unit and the electric conductivity of the nutrient solution measured by the second electric conductivity measuring unit. The supply of the fertilizer by a supply part is controlled. The liquid supply apparatus of Claim 1 or 2 characterized by the above-mentioned.

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