JPH0553455U - Micro flow rate adjusting device for chemicals - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an apparatus capable of adjusting the mixing of a minute flow rate of a chemical solution into raw water by using only a flow rate sensor that detects a normal flow rate. [Configuration] The flow rate of the bypass flow passage 21 is kept constant by a bypass flow rate sensor 22 and a bypass flow rate control valve 23,
An offset value is given to the mixed flow rate sensor 24 in the range of the normal flow rate. Then, the main pipe flow sensor 30 provided in the main pipe 20.
Then, the controller 28 calculates the respective flow rate ratios of the mixed flow rate sensor 24 and detects a minute flow rate change with respect to the offset value, thereby controlling the mixed flow rate control valve 25 provided in the chemical liquid pipe 27.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a device for diluting and mixing a chemical liquid such as liquid fertilizer at an arbitrary flow rate at a constant ratio in an automatic irrigation system, a hydroponic cultivation system, etc., in particular, without using an expensive high-sensitive precise flow sensor, The present invention relates to a device 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 general popular type flow rate sensors.

[0002]

[Prior Art]

 When cultivating plants such as vegetables using an automatic irrigation system, a hydroponic cultivation system, etc., various systems have been proposed for mixing a chemical solution such as a liquid fertilizer into raw water in a desired amount. For example, Japanese Utility Model Laid-Open No. 64-429 can be cited. In the publication, as shown in FIG. 2, the flow rate of the raw water flowing through the main pipe 1 is detected by a pulse type main pipe flow rate sensor 2, while the liquid fertilizer is sent from a liquid fertilizer tank 6 under pressure by a pump 7. The flow rate of the liquid fertilizer is also detected by the pulse type liquid fertilizer flow rate sensor 3 at the same time when the main pipe 1 merges and mixes. Then, the detection results of these two sensors 2 and 3 are sequentially sent to the controller 4 for comparison calculation, and the control valve is controlled so that the dilution ratio (liquid fertilizer flow rate) determined by the external magnification setting pulse oscillator 8 is obtained. 5 is adjusted. That is, the ratio of the detection values of the respective flow rate sensors 2 and 3 determines the predetermined designated magnification, and the range of this designated magnification is largely dependent on the characteristics of the individual flow rate sensors 2 and 3. The magnification is generally about several hundreds to 1000 times.

[0003]

[Problems to be solved by the device]

 Today, when plants such as vegetables are cultivated using an automatic irrigation system or a hydroponic cultivation system, a liquid chemical such as liquid fertilizer is often used depending on the stage of development, the state of development, or the type of plant. There is a need for detailed consideration, that is, a minute adjustment, in the supply of water. Further, even in the case of cultivating general plants, it is required to increase the dilution ratio with the recent improvement in the performance of liquid chemicals such as liquid fertilizers, that is, the higher concentration per unit amount.

In such cases, if the irrigation system is fairly large, it is easy to increase the dilution ratio because the flow rate of raw water flowing through the main pipe is quite large. The liquid fertilizer flow rate sensor 3 used in 1) requires a means for detecting a minute flow rate of a chemical liquid such as liquid fertilizer, for example, a flow rate of about several cc per minute. However, in a general-purpose type flow sensor for detecting a normal flow rate, which has a configuration as shown in FIG. 3 and has been conventionally used, the lower limit of its sensitivity is about several tens of cc per minute, so It was impossible to detect a large flow rate.

That is, such a rotary type flow sensor 2 or 3 sensitively responds to a good response within the dynamic range, for example, a change amount of about 1 cc, but is extremely low outside the range. In the flow rate region, the fluid 12 cannot rotate the rotary plate 10 due to friction loss of the shaft portion 13 of the rotary plate 10 in the sensor 2 or 3 shown in FIG. There is an unavoidable structural problem that the fluid 12 cannot emit a signal and the fluid 12 leaks from the primary side 14 of the flow rate sensor 2 or 3 to the secondary side 15.

Therefore, in order to adjust the minute flow rate of the liquid fertilizer with the system as shown in FIG. 2, the liquid fertilizer flow rate sensor 3 is equipped with a high-sensitivity precision flow rate sensor capable of obtaining stable operation even in a low flow rate range. Will be needed. Then, the controller 4 controls the liquid fertilizer control valve 5 to adjust the minute flow rate of the liquid fertilizer based on the detection result thus obtained and the detection result of the main pipe flow rate sensor 2.

However, the high-sensitivity precision flow rate sensor is not only very expensive in itself, but also the detection circuit and the like attached thereto are complicated. For this reason, the system as a whole is extremely expensive, and since it is a precision device, the occurrence of troubles such as breakdowns will increase, which imposes a considerable burden on the farmer in terms of capital investment and facility management. Was becoming.

The present invention has been developed in view of such a situation, and an object thereof is to stabilize the flow sensor by a simple structure in which inexpensive general-purpose type flow sensors are appropriately combined. By effectively utilizing the good characteristics in the operating point, that is, in the dynamic range, it is possible to obtain the detection accuracy equivalent to that of the high-sensitivity precision flow sensor, and moreover, compared to the system using the high-sensitivity precision flow sensor. It is to provide a device that adjusts a minute flow rate of a chemical liquid that is far cheaper.

[0009]

[Means for Solving the Problems]

In order to achieve the above object, in the present invention, in a device for proportionally mixing a chemical liquid of an arbitrary flow rate at an appropriate position of the main pipe through which the raw water flows, the main pipe is provided with a main pipe flow rate detecting means and a bypass flow path. a bypass flow rate constant flow means in the bypass passage, and the mixed confluent amount control means for mixing the liquid medicine to bypass flow path is provided with a mixed flow rate detecting means, the flow rate of the chemical to be mixed here, detection of the main flow rate detecting means The configuration is characterized in that a calculation means for calculating the result and the detection result of the mixed flow rate detection means is provided and the mixed flow rate control means is controlled based on this calculation result. In this case, a bypass flow path that branches from this main pipe and joins with the main pipe again downstream of this branch point is provided at an appropriate position on the main pipe together with the main pipe flow rate detection means. In this order, a bypass flow rate detecting means, a bypass flow rate controlling means, and a mixing flow rate detecting means are arranged, while the mixing flow rate controlling means is arranged at an appropriate position of the chemical liquid pipe guided from the chemical liquid tank, and the mixing flow rate controlling means is arranged. The outflow side of the flow rate control means is connected at the midpoint between the bypass flow rate control means and the mixed flow rate detection means of the bypass flow passage so that it can be mixed with the raw water flowing through the bypass flow passage. It is preferable that a detection means, a bypass flow rate detection means, and a calculation means for appropriately calculating the detection result of the mixed flow rate detection means are provided, and the mixed flow rate control means is controlled by the calculation result. Bypass flow rate detecting unit, mixed flow rate detecting means, and main flow sensing hand stage using each same member also the bypass flow rate control means, the mixed flow rate control means is preferably used, respectively identical members.

[0010]

[Action]

 With the above configuration, the present invention operates as follows. First, the main pipe flow rate F is detected by the main pipe flow rate detecting means, 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 introduced from the main pipe by the bypass passage. Then, an arbitrary flow rate of the chemical solution ΔF is added to the offset value Fo in the bypass flow path, and as a result, the mixed flow rate detection means detects Fo + ΔF = Fm. Then, 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, and the flow rate ΔF of the chemical liquid is controlled to obtain a desired dilution ratio.

That is, in the present invention, since the portion of the mixed flow rate detecting means having a good response within the dynamic range is utilized, a minute flow rate change of the chemical liquid is replaced within this dynamic range. For this reason, the constant flow amount of the bypass flow rate means keeps the flow rate of the bypass flow path at least a constant value equal to or higher than the minimum effective sensitivity of the mixed flow rate detection means, and this value is given to the mixed flow rate detection means as the offset value Fo. Further, since the outflow side pipe end of the chemical liquid pipe introduced from the chemical liquid tank is connected so as to be able to mix between the bypass flow rate constant flow means and the mixing flow rate detection means, the chemical liquid has the above offset value Fo. The mixed flow rate value Fm to which the flow rate ΔF of is added is detected with the maximum effective sensitivity F max of the mixed flow rate detection means as the upper limit. The flow rate ΔF of the added chemical liquid 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 and the mixed flow rate control means is controlled to adjust the chemical liquid having a minute flow rate.

[0012]

【Example】

 FIG. 1 is a circuit diagram showing an embodiment of the present invention, which is specifically configured as follows. First, at a suitable position of the main pipe 20 through which the raw water pressurized by the pump 31 is fed, a bypass passage 21 is branched from the main pipe 20 and joined to the main pipe 20 again downstream from the branch point. There is. In this bypass flow passage 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, while the chemical liquid pipe 27 led from a chemical liquid tank 26 is appropriately arranged. A mixing flow rate control valve 25 is disposed at the position, and the outflow side pipe end of the chemical liquid pipe 27 is provided at the intermediate point between the bypass flow rate control valve and the mixing flow rate sensor 24 in the bypass flow channel 21 described above. It is connected so that it can be mixed with the raw water flowing through 21.

Further, a second bypass passage 29 is provided on the downstream side of the confluence point of the bypass passage 21 of the main pipe 20, a main pipe flow sensor 30 is provided there, and a bypass flow of the main pipe 20 is provided. A check valve 32 is provided at an intermediate position between the junction and the branch point of the passage 21. The detection outputs of the main pipe flow rate sensor 30, the bypass flow rate sensor 23, and the mixed flow rate sensor 24 are connected to the controller 28, and the control output of this controller is connected to the bypass flow rate control valve 23 and the mixed flow rate control valve 25. To be done.

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

The outflow side pipe end of the chemical liquid pipe 27 having the mixing flow rate control valve 25, which is guided from the chemical liquid tank 26, is connected between the bypass flow valve 23 and the mixing flow sensor 24 so that mixing can be performed. Therefore, the mixed value Fm obtained by adding the flow rate ΔF of the chemical liquid to the offset value Fo is detected with the upper limit of the maximum effective sensitivity Fmax of the mixed flow sensor 24, which is 1000 cc / min in this embodiment. 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 / min ~ 965 cc / min.

The detection result obtained here is sent to the controller 28, and the indicated magnification F r is calculated by the output Fm = Fo + ΔF of the mixed flow rate sensor 24 and the output F of the main pipe flow rate sensor 30. This calculation is performed as follows: Fr = (Fm-Fo) / F∴Fr = ΔF / F The mixed flow rate valve 25 is controlled so as to keep a predetermined designated magnification constant. For example, when the designated magnification is 1/20000, the main pipe flow rate F is 100,000 cc / min, and the offset value Fo is 50 cc / min, the controller 28 calculates the liquid fertilizer flow rate ΔF by 5 cc / min according to the above equation. The mixed flow rate limiting valve 25 is controlled so that

In the present embodiment, in order to suppress these costs as much as possible, the above-mentioned sensors 22, 24, and 30 are the same parts. For this reason, in the present embodiment, the raw water is diverted in the second bypass flow passage 29 provided in the main pipe 20 so that the main pipe flow rate can be detected by such a sensor, that is, a sensor capable of detecting only 35 cc to 1000 cc / min. I am letting you. Further, the check valve 32 of the main pipe 20 prevents the reverse flow of raw water when the pump 31 is stopped.

As described above, each of the flow rate sensors 22, 24, and 30 used here is an inexpensive rotary sensor that has been conventionally used, and each of the flow rate control valves 23 and 25 is equipped with an electric actuator. The above-mentioned synthetic resin ball valve is used, and the controller 28 is composed of an 8-bit CPU that can perform precise control relatively easily and at low cost. However, such members are not limited to those used here, and various members can be used. For example, other types are used for the flow rate sensors 22, 24, and 30, but electric or fluid-actuator-mounted butterfly valves are used for the flow rate control valves 23 and 25, and an analog type is used for the controller 28. You may use the feedback controller of. Therefore, it can be configured in various modes by appropriately selecting it at the time of implementation.

[0019]

[Effect of the device]

 As is clear from the above description, the present invention has various excellent effects as described below. In other words, the low-priced general-purpose type flow sensor that has been used in the past is used as it is, so the conventional problem that the product price of the entire system is high is effectively solved. Moreover, the present invention realizes a minute flow rate adjustment with high accuracy as well as the case of using an expensive high-sensitivity precision sensor, although it has a simple structure, and has a simple structure and a corrosion-resistant member. Thanks to the adoption, there is no fear of failure. In addition, by sharing the components, it is possible to further reduce the product price and significantly reduce the system maintenance burden. In other words, such a structure can significantly reduce the economic burden on the production equipment for the agricultural business, and as a result, have the effect of contributing to the interests of general consumers. There is.

[Brief description of 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 diagram showing the structure of a rotary flow sensor in a conventional example.

[Explanation of symbols]

 20 Main Pipe 21 Bypass Flow Path 22 Bypass Flow Rate Sensor 23 Bypass Flow Rate Limiting Valve 24 Mixing Flow Rate Sensor 25 Mixing Flow Rate Limiting Valve 28 Controller 30 Main Pipe Flow Rate Sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G05D 11/02 7001-3H

Claims (3)

[Scope of utility model registration request] 1. A device for proportionally mixing a chemical solution at an arbitrary flow rate at an appropriate position of a main pipe through which raw water flows, in which a main pipe flow rate detection means and a bypass flow passage are provided, and a bypass flow constant flow is provided in this bypass flow passage. 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 a chemical liquid, characterized in that a calculation means for calculating a result is provided and the mixed flow rate control means is controlled by the calculation result. 2. A bypass flow path is provided at an appropriate position of the main pipe together with the main pipe flow rate detection means, and a bypass flow path that branches from this main pipe and joins the main pipe again downstream from this branch point is provided at this branch flow path. 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 closer one, while the mixing flow rate controlling means is arranged at an appropriate position of the chemical liquid pipe led from the chemical liquid tank. The outflow side of the mixed flow rate control means is connected at an intermediate point between the bypass flow rate control means and the mixed flow rate detection means of the bypass flow passage so that it can be mixed with the raw water flowing through the bypass flow passage, It is characterized in that a detection means, a bypass flow rate detection means, and a calculation means for appropriately calculating the detection result of the mixed flow rate detection means are provided, and the mixed flow rate control means is controlled by this calculation result. Item 2. A minute flow rate adjusting device for a chemical solution according to Item 1. 3. The bypass flow rate detecting means, the mixed flow rate detecting means, and the main pipe flow rate detecting means use the same member, respectively.
Further, the bypass flow rate control means and the mixed flow rate control means use the same member respectively, and the minute flow rate adjusting device for chemical liquid according to claim 1 or 2.