JP2556232Y2 - Fine flow rate adjustment device for chemicals - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for diluting and mixing a certain amount of a liquid chemical such as a liquid fertilizer in an automatic irrigation system or a hydroponic system at a constant rate. The present invention relates to an apparatus capable of adjusting a minute flow rate of a chemical solution with the same accuracy as a system using a high-sensitivity precision flow rate sensor by appropriately combining an inexpensive general-purpose flow rate sensor without using the same.

[0002]

2. Description of the Related Art When cultivating plants such as vegetables using an automatic irrigation system or a hydroponic system, various systems have been proposed for mixing chemical liquids such as liquid fertilizer into raw water in a predetermined desired amount. Have been. For example,
429 can be cited. In this publication, as shown in FIG. 2, the flow rate of raw water flowing through the main pipe 1 is detected by a pulse type main pipe flow sensor 2, while the liquid fertilizer is pressurized by a pump 7 from a liquid fertilizer tank 6 and sent out. At the same time as they are mixed and mixed in the main pipe 1, the flow rate of the liquid fertilizer is also detected by the pulse-type liquid fertilizer flow rate sensor 3. The detection results of these two sensors 2 and 3 are successively sent to the controller 4 to be compared and calculated, and the control valve 5 is controlled so that the dilution ratio (liquid fertilizer flow rate) determined by the pulse generator 8 for setting the external magnification is obtained. Is adjusted. In other words, the predetermined indicated magnification is determined by the ratio of the detection values of the respective flow sensors 2 and 3, and the range of the indicated magnification is largely affected by the characteristics of the individual flow sensors 2 and 3, and the Magnification is also generally several hundred to 1,000 times.

[0003]

[Problems to be Solved by the Invention] Today, when plants such as vegetables are cultivated using an automatic irrigation system or a hydroponic cultivation system, depending on the stage of development, the state of development, or the type of plant, Often, careful consideration of the supply of chemicals such as liquid fertilizers, that is, fine adjustment, is required. In addition, even when cultivating general plants, it is required to increase the dilution ratio of chemical liquids such as liquid fertilizers in recent years with high performance, that is, with high concentration per unit amount.

[0004] In such a case, it is easy to increase the dilution ratio because the flow rate of the raw water flowing through the main pipe is quite large in a fairly large-scale irrigation system. The liquid fertilizer flow rate sensor 3 used has a minute flow rate of a chemical solution such as a liquid fertilizer, for example, several cc per minute.
A means for detecting the flow rate from the degree is required. However, in a general-purpose type flow sensor for detecting a normal flow rate, as conventionally used in a configuration as shown in FIG.
Since the lower limit of the sensitivity is about several tens of cc per minute,
Detection of minute flow rates was not possible.

[0005] That is, such a rotary flow sensor 2
Or 3 responds well to a good response within the dynamic range, for example, a change amount of about 1 cc,
In a very low flow rate range such as out of this range, the rotating plate 10 in the sensor 2 or 3 shown in FIG.
The fluid 12 cannot rotate the rotary plate 10 due to friction loss of the shaft portion 13 of the
Cannot generate an accurate detection signal, and has a structurally inevitable problem that the fluid 12 leaks from the primary side 14 to the secondary side 15 of the flow sensor 2 or 3.

Therefore, in order to finely adjust the flow rate of the liquid fertilizer in the system shown in FIG. 2, it is necessary to equip the liquid fertilizer flow rate sensor 3 with a high-precision precision flow rate sensor capable of obtaining a stable operation even in a low flow rate range. Is required. The controller 4 controls the control valve 5 of the liquid fertilizer on the basis of the detection result obtained by this and the detection result of the main pipe flow sensor 2 to adjust the minute flow rate of the liquid fertilizer.

However, a high-precision precision flow sensor is
Not only is it very expensive per se, but also complicating detection circuits and the like that accompany it. For this reason, the entire system is extremely expensive, and the precision equipment increases the occurrence of troubles such as breakdowns, which imposes a considerable burden on farmers in terms of capital investment and equipment management. I was

The present invention has been developed in view of such a situation, and the object thereof is to realize a stable operation of the flow sensor by a simple configuration appropriately combining an inexpensive general-purpose flow sensor. By effectively utilizing the point, that is, good characteristics within the dynamic range, it is possible to obtain detection accuracy equivalent to that of a high-sensitivity precision flow sensor, and far more than a system using a high-sensitivity precision flow sensor. It is an object of the present invention to provide an inexpensive device for adjusting the minute flow rate of a chemical solution.

[0009]

In order to achieve the above-mentioned object, according to the present invention, at an appropriate position of a main pipe through which raw water flows,
An apparatus for proportional mixing any flow of the chemical solution, the main flow rate detecting means in this main pipe, a bypass passage provided, and the bypass flow rate constant flow means in the bypass passage, mixed confluence amount control for mixing chemicals into the bypass passage Means for detecting the flow rate of the chemical solution mixed therewith, and calculating means for calculating the detection result of the main pipe flow rate detecting means and the detection result of the mixing flow rate detecting means. The configuration is such that control of the control means is performed. In this case, a bypass flow path is provided at an appropriate position of the main pipe together with the main pipe flow rate detecting means and branches off from the main pipe and joins the main pipe again downstream of the branch point. In order, a bypass flow rate detecting means, a bypass flow rate controlling means, and a mixed flow rate detecting means are provided. On the other hand, a mixed flow rate controlling means is provided at an appropriate position of a chemical solution pipe led from a chemical solution tank. The outflow side of the control means is connected at a midpoint between the bypass flow rate control means and the mixed flow rate detection means of the bypass flow path so as to be mixable with raw water flowing through the bypass flow path, and the detection result of the main pipe flow rate detection means is provided. And a calculating means for appropriately calculating the detection result of the mixed flow rate detecting means, and controlling the mixed flow rate controlling means based on the calculated result. Flow rate detecting means, mixed flow rate detecting means, and main flow rate detection means with the same members, respectively, also the bypass flow rate control means, the mixed flow rate control means is preferably used, respectively identical members.

[0010]

With the above arrangement, the present invention performs the following operations.
First, the main pipe flow rate detecting means detects the main pipe flow rate F, and a constant offset value Fo is given to the mixed flow rate detecting means by the bypass flow rate constant flow means of the raw water led from the main pipe through the bypass flow path. Then, an arbitrary flow rate of the liquid medicine ΔF is added to the offset value Fo in the bypass flow path. As a result, the mixed flow rate detection means detects Fo + ΔF = Fm. Then, a desired dilution ratio is obtained by appropriately calculating the detection result Fm of the mixed flow rate detection means and the detection result F of the main pipe flow rate detection means and controlling the flow rate ΔF of the chemical solution.

That is, in the present invention, since a portion having a good response within the dynamic range of the mixed flow rate detecting means is used, a minute change in the flow rate of the chemical solution is replaced within this dynamic range. For this reason, the flow rate of the bypass flow path is kept at a constant value at least equal to or greater than the minimum effective sensitivity of the mixed flow rate detecting means by the bypass flow rate constant flow means, and this is given to the mixed flow rate detecting means as an offset value Fo. Since the outflow-side pipe end of the chemical solution pipe led from the chemical solution tank is connected so as to be able to mix between the bypass flow rate constant flow means and the mixed flow rate detection means, the chemical solution is adjusted to the above-described offset value Fo. Mixed flow value Fm to which the flow rate ΔF is added
Are detected with the maximum effective sensitivity Fmax of the mixed flow rate detecting means as an upper limit. The flow rate ΔF of the chemical solution to be added is 0 ≦ ΔF ≦ (Fmax−Fo). The detection result Fm of the mixed flow rate detection means and the detection result F of the main pipe flow rate detection means are appropriately calculated to control the mixed flow rate control means, thereby adjusting the chemical solution at a minute flow rate.

[0012]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, which is specifically configured as follows. First, the main pipe 20 through which raw water flows while being pressurized and sent to the pump 31.
A bypass flow path 21 is provided at an appropriate position of the main pipe 20 for branching from the main pipe 20 and rejoining the main pipe 20 downstream of the branch point. In this bypass flow path 21, a bypass flow rate sensor 22, a bypass flow rate control valve 23, and a mixed flow rate sensor 24 are arranged in this order from the side closer to the branch point.
A mixing flow rate control valve 25 is disposed at an appropriate position of the chemical liquid pipe 27 led from the chemical liquid tank 26, and the outlet pipe end of the chemical liquid pipe 27 is mixed with the bypass flow rate control valve of the bypass flow path 21. An intermediate point of the flow sensor 24 is connected so as to be mixable with raw water flowing through the bypass flow path 21.

The main pipe 20 has the above-mentioned bypass passage 21.
A second bypass passage 29 is provided downstream of the junction of
The main pipe 20 is provided with a main pipe flow sensor 30. The check valve 3 is provided at an intermediate position between the branch point and the junction of the bypass flow path 21 of the main pipe 20.
2 are provided. Each detection output of the main pipe flow sensor 30, the bypass flow sensor 23, and the mixed flow sensor 24 is connected to the controller 28, and the control output of this controller is connected to the bypass flow control valve 23 and the mixed flow control valve 25. .

Next, the operation of this embodiment will be described. In the present invention, as described above, the mixed flow rate sensor 24
Since a portion having a good response within the dynamic range of, for example, a range of 35 cc to 1000 cc is used, the minute flow rate change ΔF of the liquid fertilizer is replaced so as to change within this dynamic range. Therefore, by controlling the bypass flow rate valve 23 with the detection output of the bypass flow rate sensor 22, the flow rate of the bypass flow path 21 is set to at least the minimum effective sensitivity of the mixed flow rate sensor 24, that is, 35c.
c / min or more, and this is supplied to the mixed flow sensor 24 as an offset flow value Fo.

The outflow-side pipe end of the chemical solution pipe 27 having the mixing flow rate control valve 25 led from the chemical solution tank 26 is connected to the bypass flow rate valve 23 and the mixing flow rate sensor 2.
4, the mixture value Fm obtained by adding the flow rate ΔF of the chemical solution to the offset value Fo is the maximum effective sensitivity Fma of the mixture flow rate sensor 24.
x, in the present embodiment, detection is performed with an upper limit of 1000 cc / minute. Since the flow rate ΔF of the liquid fertilizer to be added is 0 ≦ ΔF ≦ (Fmax−Fo), the specific value in this example is as follows: 0 ≦ ΔF ≦ (1000-35) ∴ΔF = 0 cc / minute ~ 965cc / min.

The detection result obtained here is stored in the controller 2
8 and the output Fm = Fo of the mixed flow rate sensor 24
The instruction magnification Fr is calculated from + ΔF and the output F of the main pipe flow sensor 30. This calculation is performed as follows. Fr = (Fm−Fo) / F∴Fr = ΔF / F The mixing flow rate valve 25 is controlled so as to keep a predetermined instruction magnification constant. For example, the indicated magnification is 1/2
0000, the main pipe flow rate F is 100,000 cc / min,
When the offset value Fo is 50 cc / minute, the controller 28 calculates the flow rate ΔF of the liquid fertilizer according to the above equation.
Is controlled to be 5 cc / min.

In this embodiment, in order to minimize these costs, the above-mentioned sensors 22, 24 and 30 are made of the same component. For this reason, in this embodiment, such a sensor that can detect the main pipe flow rate, that is, a sensor that can detect only 35 cc to 1000 cc / min, can detect a large capacity.
Raw water is divided by a second bypass passage 29 provided in the main pipe 20. The check valve 32 of the main pipe 20 is connected to the pump 31
To prevent backflow of raw water when the plant is stopped.

As described above, each of the flow sensors 22, 24, and 30 used here is a conventional inexpensive rotary sensor, and each of the flow control valves 23, 2 is used.
Reference numeral 5 denotes a synthetic resin ball valve on which an electric actuator is mounted, and the controller 28 includes an 8-bit CPU which can perform precise control relatively easily and at low cost. However, such members are not limited to those used here, and can be implemented using various members. For example, other types of flow sensors 22, 24, and 30 are used, and each flow control valve 2
An electric or fluid actuator mounted butterfly valve may be used for 3 and 25, and an analog feedback controller may be used for the controller 28. Therefore, it can be configured in various modes by appropriate selection during implementation.

[0019]

As apparent from the above description, the present invention has a number of excellent effects as described below. That is, since the inexpensive general-use type flow sensor that has been used conventionally is used as it is, the conventional problem that the product price of the entire system is high is effectively solved. In addition, the present invention realizes fine flow rate adjustment with high accuracy, as in the case of using an expensive high-sensitivity precision sensor, despite its simple configuration, and has a simple configuration and a corrosion-resistant member. With the adoption, there is no worry about failure. In addition, the common use of the constituent members has resulted in a further reduction in the product price, and the burden of maintenance management of the system has been greatly reduced. In other words, such a configuration can significantly reduce the economic burden on the production equipment for the agricultural business, and as a result, has the effect of leading to the benefits of general consumers.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional example.

FIG. 3 is a schematic view showing a structure of a rotary flow sensor in a conventional example.

[Explanation of symbols]

 Reference Signs List 20 main pipe 21 bypass flow path 22 bypass flow sensor 23 bypass flow restriction valve 24 mixed flow sensor 25 mixed flow restriction valve 28 controller 30 main pipe flow sensor

Claims (3)

(57) [Scope of request for utility model registration] 1. An apparatus for mixing a chemical solution of an arbitrary flow rate in an appropriate position in a main pipe through which raw water flows, wherein said main pipe is provided with a main pipe flow rate detecting means and a bypass flow path. means, confused merging amount control means for mixing the liquid medicine to bypass flow path, a mixture flow rate detection means is provided, the flow rate of the chemical liquid to be mixed here is a detection result of the main flow rate detecting means, the detection of the mixed flow rate detecting means A minute flow rate adjusting device for chemical liquids, comprising a calculation means for calculating the result, and controlling the mixing flow rate control means based on the calculation result. 2. A bypass flow path is provided at an appropriate position of the main pipe together with a main pipe flow rate detecting means, and branches off from the main pipe and joins the main pipe again downstream of the branch point. The bypass flow rate detecting means, the bypass flow rate controlling means, and the mixed flow rate detecting means are arranged in order from the closest one.On the other hand, the mixed flow rate controlling means is arranged at an appropriate position of the chemical solution pipe led from the chemical solution tank. The outflow side of the mixed flow rate control means is connected to the raw water flowing through the bypass flow path at an intermediate point between the bypass flow rate control means and the mixed flow rate detection means of the bypass flow path so that the main pipe flow rate detection means can be mixed. A calculation means for appropriately calculating the detection result, the bypass flow rate detection means, and the detection result of the mixed flow rate detection means, and controlling the mixed flow rate control means based on the calculation result. Item 6. The minute flow rate adjusting device for a drug solution according to Item 1. 3. The same member is used for each of a bypass flow rate detecting means, a mixed flow rate detecting means, and a main pipe flow rate detecting means.
3. The device according to claim 1, wherein the bypass flow rate control means and the mixed flow rate control means use the same member.