Soil temperature control system

Abstract

To provide a soil temperature control system that has a simple structure, suppresses the maximum energy consumption of the heat source, and controls soil temperature in an energy-efficient manner. [Solution] This soil temperature control system comprises multiple insulation tubes 3, each containing an insulation bag 30 placed over a block of soil divided into multiple sections, and a heater 31 and air placed inside the insulation bag 30, as well as a control means for turning the heaters 31 of the multiple insulation tubes 3 on and off for each block. By turning the heaters 31 of the multiple insulation tubes 3 on and off for each block, the simultaneous activation of the heat sources in each block is suppressed.

Description

Technical Field

[0001] The present invention relates to a soil temperature control system for heating or cooling the soil of a farm.

Background Art

[0002] In the growth of crops, it is important to directly control the temperature of the soil. As a method of heating the soil, for example, there is a method of installing an electric heater to warm the soil (see Patent Documents 1 and 2). On the other hand, as a method of cooling the soil, for example, there is a method of sending temperature-controlled air around a container that houses the soil (see Patent Document 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the former method of heating the soil, since it is necessary to conclude a basic contract with the power company according to the number of installed electric heaters, the basic contract power becomes high. Also, a basic charge according to the number of installed electric heaters is generated even in months when the electric heaters are not used. On the other hand, in the latter method of cooling the soil, since a cultivation container with a special structure is used, a large investment for newly installing dedicated equipment is required.

[0005] Therefore, an object of the present invention is to provide a soil temperature control system that can suppress the maximum energy consumption of a heat source such as an electric heater with a simple structure and control the soil temperature with high energy efficiency. Other challenges and novel features will become apparent from the description and accompanying drawings in this specification. [Means for solving the problem]

[0006] The soil temperature control system of the present invention comprises multiple insulation tubes, each containing an insulation bag placed over a block of soil divided into multiple sections, and a heat source and gas placed inside the insulation bag; and control means for turning the heat sources of the multiple insulation tubes on and off for each block. The heat source is, for example, a heating source, a cooling source, or a hot and cold heating source.

[0007] By switching the heat sources of multiple insulation tubes on and off for each block, it is possible to prevent all block heat sources from being turned on simultaneously. In addition, the insulation tubes have a larger contact area with the soil surface due to the insulation bag containing the heat source and gas, which increases the efficiency of heat transfer to the soil. Furthermore, since the gas placed in the insulation bag along with the heat source has low thermal conductivity, the heat retention effect of the heat source (whether hot or cold) is enhanced, allowing for energy-efficient control of the soil temperature.

[0008] Furthermore, it is desirable that the soil temperature control system of the present invention has a functional material on either the upper side and / or the lower side of the insulation bag. This allows the heat or cold from the heat source inside the insulation bag covering the soil to be controlled more energy-efficiently by the function of the functional material on either the upper side and / or the lower side of the insulation bag, and a positive effect on plant growth can be expected. [Effects of the Invention]

[0009] (1) By having multiple insulation tubes, each containing an insulation bag to be placed over multiple blocks of soil, and a heat source and gas to be placed inside the insulation bag, and a control means to turn the heat sources of the multiple insulation tubes on and off for each block, it is possible to control the soil temperature in an energy-efficient manner while suppressing the maximum energy consumption of heat sources such as electric heaters with a simple structure.

[0010] (2) By having a functional material on either the top or bottom surface or both of the insulation bag, soil temperature can be controlled more energy-efficiently. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of an entire farm equipped with a soil temperature control system according to the first embodiment of the present invention. [Figure 2] Figure 1 is a schematic diagram of a cultivation bench. [Figure 3] Figure 2 is a cross-sectional view of the cultivation bench. [Figure 4] Figure 2 shows details of the insulation tube, where (a) is a plan view, (b) is a cross-sectional view of (a) along line AA, and (c) is a cross-sectional view of (a) along line BB. [Figure 5] This is a diagram showing the configuration of a soil temperature control system according to the first embodiment of the present invention. [Figure 6] This is a temperature control flowchart of the soil temperature control system in the first embodiment of the present invention. [Figure 7] This is an explanatory diagram showing an example of temperature control settings by the soil temperature control system in the first embodiment of the present invention. [Figure 8] This is a schematic diagram showing an example of the construction of a soil temperature control system according to the first embodiment of the present invention. [Figure 9] This figure shows a modified example 1 of the temperature control flow of the soil temperature control system in the first embodiment of the present invention. [Figure 10] This figure shows a modified example 2 of the temperature control flow of the soil temperature control system in the first embodiment of the present invention. [Figure 11] This figure shows details of the insulation tube of the soil temperature control system in a second embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view of (a) along line AA, and (c) is a cross-sectional view of (a) along line BB. [Figure 12]A diagram showing details of the heat-insulating tube of the soil temperature control system in the third embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view taken along line A-A of (a), and (c) is a cross-sectional view taken along line B-B of (a). [Figure 13] A diagram showing details of the heat-insulating tube of the soil temperature control system in the fourth embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view taken along line A-A of (a), and (c) is a cross-sectional view taken along line B-B of (a). [Figure 14] A diagram showing details of the heat-insulating tube of the soil temperature control system in the fifth embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view taken along line A-A of (a), and (c) is a cross-sectional view taken along line B-B of (a). [Figure 15] A diagram showing details of the heat-insulating tube of the soil temperature control system in the sixth embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view taken along line A-A of (a), and (c) is a cross-sectional view taken along line B-B of (a). [Figure 16] (a) is a diagram showing the heating test results according to Example 1, and (b) is a diagram showing the heating test results according to Comparative Example 1. [Figure 17] (a) is a diagram showing the heating test results according to Example 2, and (b) is a diagram showing the heating test results according to Comparative Example 2.

Embodiments for Carrying Out the Invention

[0012] <Embodiment 1> Figure 1 is a schematic diagram of the entire farm equipped with the soil temperature control system in the first embodiment of the present invention, Figure 2 is a schematic diagram of the cultivation bench in Figure 1, Figure 3 is a cross-sectional view of the cultivation bench in Figure 2, Figure 4 is a diagram showing details of the heat-insulating tube in Figure 2, where (a) is a plan view, (b) is a cross-sectional view taken along line A-A of (a), (c) is a cross-sectional view taken along line B-B of (a), and Figure 5 is a configuration diagram of the soil temperature control system in the first embodiment of the present invention.

[0013] As shown in Figure 1, the strawberry farm 1, which is equipped with a soil temperature control system in the first embodiment, is divided into several blocks B1, B2, B3, and B4. Each block B1 to B4 is equipped with five rows of cultivation benches 2. The cultivation benches 2 in the first embodiment are for elevated cultivation of strawberries.

[0014] As shown in Figures 2 and 3, the cultivation bench 2 has a cultivation tank 21 formed on a frame 20. The cultivation tank 21 consists of a plurality of straight pipes 22 extending horizontally on the frame 20 and a synthetic resin sheet 23, such as polyethylene (PE) film, loosely stretched between the plurality of straight pipes 22. In addition, the cultivation tank 21 is filled with culture soil 24, which serves as the soil, so that the center is slightly raised.

[0015] The growing medium 24 is covered with an insulating tube 3. Strawberry seedlings are planted in the parts of the growing medium 24 that are not covered by the insulating tube 3. The insulating tube 3 comprises an insulating bag 30 and a heater 31 as a heat source. The insulating bag 30 is long in the longitudinal direction of the growing tank 21. The heater 31 is an electric heater. As shown in Figure 4, the heater 31 is sealed inside the insulating bag 30 together with air 34 as a gas. The insulating bag 30 is a cylindrical bag made of synthetic resin film such as polypropylene (PP) or nylon polyethylene (NYPE). The heater 31 is inserted in the longitudinal direction X of the insulating bag 30.

[0016] The ends of the thermal insulation bag 30 in the longitudinal direction X are bonded together to form adhesive sections 32, sealing air 34 inside the thermal insulation bag 30. Adhesive sections 33 are also provided at predetermined intervals along the longitudinal direction X of the thermal insulation bag 30. These adhesive sections 33 are formed by bonding the upper and lower surfaces of the thermal insulation bag 30 in the width direction Y. These adhesive sections 33 prevent the thermal insulation bag 30, which is filled with air 34, from expanding too much, and maintain an overall thin, flat shape.

[0017] The soil temperature control system in the first embodiment includes a plurality of insulation tubes 3 that are placed over the culture soil 24 of each block B1 to B4, and a controller 4 (see Figure 5) that serves as a control means for controlling the heaters 31 of the plurality of insulation tubes 3. In the following description, the heaters 31 of blocks B1, B2, B3, and B4 may also be referred to as heaters H1, H2, H3, and H4. The controller 4 turns the heaters H1 to H4 of the plurality of insulation tubes 3 on and off for each block B1 to B4. Each block B1, B2, B3, and B4 is provided with temperature sensors S1, S2, S3, and S4, respectively.

[0018] As shown in Figure 5, the controller 4 includes a CPU (Central Processing Unit) 40, an input / output interface (I / F) 41, a power circuit breaker 42, and power switches 43-1, 43-2, 43-3, and 43-4. Temperature sensors S1 to S4 and power switches 43-1 to 4 are connected to the input / output interface 41. Heaters H1 to H4 are each connected to power switches 43-1 to 4. Power is supplied to the power circuit breaker 42 from the commercial power supply. Power switches 43-1 to 4 are connected to the power circuit breaker 42 and are powered via the power circuit breaker 42.

[0019] The temperature information values ​​acquired by the temperature sensors S1 to S4 in each block B1 to B4 are input to the CPU 40 via the input / output interface 41. Power switches 43-1 to 4 switch on and off (on / off) based on the on / off signals from each block B1 to B4 input from the CPU 40 via the input / output interface 41, thereby switching the power supply to the heaters H1 to H4 of each block B1 to B4 on and off.

[0020] Next, the control using the soil temperature control system with the above configuration will be described. Figure 6 is a temperature control flowchart of the soil temperature control system in the first embodiment. In the following description, n indicates the number of divided blocks. That is, in the first embodiment, n = 4.

[0021] (S101) Determine the set temperatures TS1 to TSn in the soil of each block B1 to Bn. (S102) The current temperature TR1 to TRn in the soil of each block B1 to Bn is measured using temperature sensors S1 to Sn installed in each block B1 to Bn. (S103) Calculate the temperature difference TD1 to TDn between the set temperatures TS1 to TSn and the current temperatures TR1 to TRn. For example, the temperature difference TD1 of block B1 is obtained by subtracting the current temperature TR1 from the set temperature TS1 (TDn = TSn - TRn). (S104) Add up the temperature differences TD1 to TDn to calculate the total temperature difference TA (TA = TD1 + TD2 + ... + TDn). (S105) Divide the temperature difference TD1 to TDn by the total temperature difference TA to calculate the percentage of energized time EP1 to EPn for heaters H1 to Hn installed in each block B1 to Bn. For example, the percentage of energized time EP1 for heater H1 installed in block B1 is obtained by dividing the temperature difference TD1 by the total temperature difference TA (EPn = TDn / TA). (S106) Multiply the energizing time ratio EP1 to EPn by the energizing period time ES to calculate the energizing times ET1 to ETn for heaters H1 to Hn installed in each block B1 to Bn. For example, the energizing time ET1 for heater H1 installed in block B1 is obtained by multiplying the energizing time ratio EP1 by the energizing period time ES (ETn = EPn × ES). The energizing period time ES is the total time (ES = ET1 + ET2 + ... + ETn) when heaters H1 to Hn in each block B1 to Bn are energized one by one according to the energizing times ET1 to ETn set for each block B1 to Bn. (S107) Based on the energizing times ET1 to ETn, heaters H1 to Hn are energized sequentially without energizing each other simultaneously. (S108) If the holding time has been reached, the process is terminated. If the holding time has not been reached, the process returns to step S102 and the process continues.

[0022] Figure 7 is an explanatory diagram showing an example of temperature control settings by the soil temperature control system in the first embodiment.

[0023] The left side of Figure 7 shows the current temperatures TR1-TR4, temperature differences TD1-TD4, energization time ratios EP1-EP4, and energization times ET1-ET4 measured or calculated in processes S102-S106 for each of the set temperatures TS1-TS4 in blocks B1-B4 of No.1-No.4, respectively. The energization cycle time ES is assumed to be 20 seconds.

[0024] The right side of Figure 7 shows the time series of times when heaters H1 to H4 of each block B1 to B4 are turned on and off by process S107, based on the calculated energizing times ET1 to ET4. As shown in the figure, heaters H1 to H4 of each block B1 to B4 are energized sequentially for each block B1 to B4 without being energized (turned on) simultaneously with each other.

[0025] In the soil temperature control system according to the first embodiment, the operating time (energizing time) of the heaters 31 (H1 to Hn) is set for each block B1 to Bn by processes S102 to S106, and the heaters 31 (H1 to Hn) are sequentially turned on and off according to the set energizing time of the heaters 31 (H1 to Hn). This suppresses the simultaneous turning on of the heaters 31 (H1 to Hn), which are the heat sources (heat sources) for each block B1 to Bn, and thus suppresses the maximum energy consumption of the heaters 31.

[0026] Furthermore, in the soil temperature control system of the first embodiment, the heat-insulating tube 3 can have a larger contact area with the surface of the culture soil 24 by the heat-insulating bag 30, thereby increasing the heat transfer efficiency to the culture soil 24. In addition, since the air 34 placed inside the heat-insulating bag 30 along with the heater 31 has low thermal conductivity, the heat retention effect of the heater 31 is enhanced, and the soil temperature can be controlled with energy efficiency.

[0027] Figure 8 is a schematic diagram showing an example of the construction of the soil temperature control system in the first embodiment. As shown in Figure 8, if the capacity of heaters H1 to H4 in each block B1 to B4 is 400W each and the number of heaters is 15, the total heater capacity is 6000W (rated current value 30A). However, since heaters H1 to H4 are not turned on simultaneously but are turned on sequentially for each block B1 to B4, the contracted power is 6KVA (200V, 30A). Note that, as shown in Figure 1 above, the cultivation bench 2 is long, so in reality, three insulation tubes 3 are arranged along the length of each row of cultivation bench 2, and the number of heaters in each block B1 to B4 is 3 tubes × 5 rows = 15. However, the number of insulation tubes 3 and the number of heaters may be changed depending on the length of the cultivation bench 2.

[0028] Next, we will describe a modified example 1 of the temperature control flow of the soil temperature control system in the first embodiment. Figure 9 shows a modified example 1 of the temperature control flow of the soil temperature control system in the first embodiment.

[0029] (S201) Determine the set temperatures TS1 to TSn in the soil of each block B1 to Bn. (S202) The current soil temperature TR1 to TRn in each block B1 to Bn is measured using temperature sensors S1 to Sn installed in each block B1 to Bn. (S203) Calculate the temperature difference TD1 to TDn between the set temperatures TS1 to TSn and the current temperatures TR1 to TRn. (S204) If all temperature differences TD1 to TDn are below the allowable range, proceed to process S210. If all temperature differences TD1 to TDn are not below the allowable range, that is, if even one exceeds the allowable range, proceed to process S205. The allowable range is set in advance, for example, 2°C. (S205) If all of the temperature differences TD1 to TDn in process S204 are not below the acceptable range, the temperature differences TD1 to TDn are added together to calculate the total temperature difference TA (TA = TD1 + TD2 + ... + TDn). (S206) Divide the temperature difference TD1~TDn by the total temperature difference TA to calculate the ratio of energized time EP1~EPn for heaters H1~Hn installed in each block B1~Bn. (S207) Multiply the energizing time ratio EP1 to EPn by the energizing period time ES to calculate the energizing time ET1 to ETn for heaters H1 to Hn installed in each block B1 to Bn. (S208) Based on the energizing times ET1 to ETn, heaters H1 to Hn are energized sequentially without energizing each other simultaneously. (S209) If the holding time has been reached, the process is terminated. If the holding time has not been reached, the process returns to step S202 and the process continues. (S210) If the temperature differences TD1 to TDn in step S204 are all below the allowable range, the heaters H1 to Hn are not energized for the energization cycle time ES. Next, proceed to step S209.

[0030] In this modified example 1, if the temperature differences TD1 to TDn are all below the acceptable range, the heaters H1 to Hn are not energized (turned on) during the energization cycle time ES. Therefore, the time during which the heat sources, heaters H1 to Hn, are on is shortened, and power consumption can be reduced.

[0031] Next, a modified example 2 of the temperature control flow of the soil temperature control system in the first embodiment will be described. Figure 10 shows a modified example 2 of the temperature control flow of the soil temperature control system in the first embodiment.

[0032] (S301) Determine the set temperatures TS1 to TSn in the soil of each block B1 to Bn. (S302) The current soil temperature TR1 to TRn in each block B1 to Bn is measured using temperature sensors S1 to Sn installed in each block B1 to Bn. (S303) Calculate the temperature difference TD1 to TDn between the set temperatures TS1 to TSn and the current temperatures TR1 to TRn. (S304) Add up the temperature differences TD1 to TDn to calculate the total temperature difference TA (TA = TD1 + TD2 + ... + TDn). (S305) Divide the temperature difference TD1~TDn by the total temperature difference TA to calculate the ratio of energized time EP1~EPn for heaters H1~Hn installed in each block B1~Bn. (S306) Multiply the energizing time ratio EP1 to EPn by the energizing period time ES to calculate the energizing time ET1 to ETn for heaters H1 to Hn installed in each block B1 to Bn. (S307) If all energizing times ET1 to ETn are less than or equal to the minimum time, proceed to process S310. If all energizing times ET1 to ETn are not less than or equal to the minimum time, that is, if at least one exceeds the minimum time, proceed to process S308. The minimum time is set in advance, for example, to 5 seconds. (S308) If in process S307 all of the energizing times ET1 to ETn are not less than or equal to the shortest time, then based on the energizing times ET1 to ETn, the heaters H1 to Hn are energized sequentially without energizing each other simultaneously. (S309) If the holding time has been reached, the process is terminated. If the holding time has not been reached, the process returns to step S302 and the process continues. (S310) If the energizing times ET1 to ETn in step S307 are all less than or equal to the shortest time, the heaters H1 to Hn are not energized for the energizing cycle time ES. Next, proceed to step S309.

[0033] In this modified example 2, if the energizing times ET1 to ETn are all less than or equal to the shortest time, the heaters H1 to Hn are not energized (turned on) during the energizing cycle time ES. Therefore, the time during which the heat sources, heaters H1 to Hn, are on is shortened, and power consumption can be reduced.

[0034] Another embodiment of the soil temperature control system of the present invention will be described below. <Embodiment 2> Figure 11 shows details of the insulation tube of a soil temperature control system in a second embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view along line AA of (a), and (c) is a cross-sectional view along line BB of (a). In Figure 11, components common to Figure 4 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0035] The soil temperature control system in the second embodiment of the present invention is configured to include a heat-insulating tube 3A as shown in Figure 11, instead of the heat-insulating tube 3 described above. The heat-insulating tube 3A has an aluminum vapor-deposited film 35 as a functional material on the lower side of the heat-insulating bag 30. By covering the culture soil 24 with this heat-insulating tube 3A, the aluminum vapor-deposited film 35 reflects radiant heat from the culture soil 24, preventing heat from escaping from the culture soil 24.

[0036] <Embodiment 3> Figure 12 shows details of the insulation tube of a soil temperature control system in a third embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view along line AA of (a), and (c) is a cross-sectional view along line BB of (a). In Figure 12, components common to Figure 4 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0037] The soil temperature control system in the third embodiment of the present invention is configured to include a heat-insulating tube 3B, as shown in Figure 12, instead of the aforementioned heat-insulating tube 3. The heat-insulating tube 3B has a functional material 36, such as a sheet or film that emits far-infrared rays or an insulating sheet, on the upper side of the heat-insulating bag 30. By covering the culture soil 24 with this heat-insulating tube 3B, the soil temperature can be controlled more energy-efficiently due to the function of the functional material 36, and a positive effect on plant growth can be expected.

[0038] For example, if a sheet or film that emits far-infrared rays is used as the functional material 36, the far-infrared rays can have a positive effect on plant growth. Also, if an insulating sheet is used as the functional material 36, it can block heat dissipation to the upper surface and prevent soil temperature from rising due to sunlight. It is also possible to use both the aluminum vapor-deposited film 35 and the functional material 36 in combination, or to reverse the upper or lower sides.

[0039] <Embodiment 4> Figure 13 shows details of the insulation tube of a soil temperature control system in a fourth embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view along line AA of (a), and (c) is a cross-sectional view along line BB of (a). In Figure 13, components common to Figure 4 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0040] The soil temperature control system in the fourth embodiment of the present invention is configured with an insulating tube 3C shown in Figure 13 instead of the insulating tube 3 described above. The insulating tube 3C is for cooling the culture soil 24 and is configured with a cold air pipe 37 instead of the heater 31 of the insulating tube 3. Cold air 37A, which serves as a heat source (cooling source), is supplied to the cold air pipe 37 and is introduced into the insulating bag 30 from the cold air pipe 37. The temperature control flow is the same as in the case of the heater 31.

[0041] In the soil temperature control system with the above configuration, by switching each block B1 to Bn on and off, it is possible to prevent the simultaneous switching on of the supply of cold air 37A, which is the heat source (cooling source) for each block B1 to Bn. This makes it possible to suppress the maximum energy consumption for supplying the cold air 37.

[0042] Furthermore, an air vent can be provided at the end of the insulation tube 3C. This allows for air to be vented even when the insulation bag 30 is full, by introducing cold air 37A into the insulation bag 30 from the cold air pipe 37. In this case, the amount of air supplied from the cold air pipe 37 can be adjusted by a flow control valve or by adjusting the rotation speed of the blower motor.

[0043] <Embodiment 5> Figure 14 shows details of the insulation tube of a soil temperature control system in a fifth embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view along line AA of (a), and (c) is a cross-sectional view along line BB of (a). In Figure 14, components common to Figures 4 and 13 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0044] The fifth embodiment of the present invention provides a soil temperature control system that includes a heat-insulating tube 3D, as shown in Figure 14, instead of the aforementioned heat-insulating tube 3. The heat-insulating tube 3D is for heating or cooling the culture soil 24 and includes a heater 31 inside the cold air pipe 37 shown in Figure 13. That is, when it is necessary to heat the culture soil 24, the heater 31 is used to warm the air 34 inside the heat-insulating bag 30. When it is necessary to cool the culture soil 24, the cold air pipe 37 is used to supply cold air 37A into the heat-insulating bag 30. Alternatively, the heater 31 may be used and the cold air 37A supplied simultaneously to adjust the temperature inside the heat-insulating bag 30.

[0045] In the soil temperature control system with the above configuration, by switching each block B1 to Bn on and off, it is possible to prevent the heaters 31 and / or the cool air 37A, which are the heat sources for each block B1 to Bn, from being turned on simultaneously. This makes it possible to suppress the maximum energy consumption required to supply the heaters 31 and / or the cool air 37A.

[0046] <Embodiment 6> Figure 15 shows details of the insulation tube of a soil temperature control system in the sixth embodiment of the present invention, where (a) is a plan view, (b) is a cross-sectional view along line AA of (a), and (c) is a cross-sectional view along line BB of (a). In Figure 15, components common to Figure 4 are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0047] The soil temperature control system in the sixth embodiment of the present invention is configured to include a heat-insulating tube 3E as shown in Figure 15, instead of the heat-insulating tube 3 described above. The heat-insulating tube 3E is for heating or cooling the culture soil 24 and is equipped with a cold air pipe 38 that supplies cold air 38A into the heat-insulating bag 30 separately from the heater 31. That is, when it is necessary to heat the culture soil 24, the heater 31 is used to heat the air 34 inside the heat-insulating bag 30. When it is necessary to cool the culture soil 24, the cold air pipe 38 is used to supply cold air 38A into the heat-insulating bag 30. Alternatively, the heater 31 and the supply of cold air 38A may be used simultaneously to adjust the temperature inside the heat-insulating bag 30.

[0048] In the soil temperature control system with the above configuration, by switching each block B1 to Bn on and off, it is possible to prevent the heaters 31 and / or cool air 38A, which are the heat sources for each block B1 to Bn, from being turned on simultaneously. This makes it possible to suppress the maximum energy consumption required to supply the heaters 31 and / or cool air 38.

[0049] In the first to sixth embodiments described above, examples using either a heating source or a cooling source as the heat source were explained. However, it is also possible to use a heating / cooling source capable of supplying both cold and hot energy, such as a heat pump. In this case, similar effects can be expected by sequentially turning the heat source on and off according to the operating time set for each block. [Examples]

[0050] <Example 1> A heating test of culture soil 24 was conducted using the soil temperature control system according to the first embodiment of the present invention. Figure 16(a) shows the results of the heating test of culture soil 24 using the soil temperature control system according to the first embodiment of the present invention (Example 1), and Figure 16(b) shows the results of the heating test of culture soil 24 when the heat-retaining bag 30 was omitted (Comparative Example 1). Note that the conditions for Example 1 and Comparative Example 1 are the same except for the presence or absence of the heat-retaining bag 30.

[0051] As shown in Figure 16, when the insulating bag 30 is present, the culture soil 24 is heated to a higher temperature at a greater depth compared to when the insulating bag 30 is absent, confirming that it is possible to control the soil temperature in an energy-efficient manner.

[0052] <Example 2> A cooling test of culture soil 24 was conducted using the soil temperature control system according to the fourth embodiment of the present invention described above. Figure 17(a) shows the results of the cooling test of culture soil 24 using the soil temperature control system according to the fourth embodiment of the present invention (Example 2), and Figure 17(b) shows the results of the cooling test of culture soil 24 when the heat-retaining bag 30 was omitted (Comparative Example 2). Note that the conditions for Example 2 and Comparative Example 2 are the same except for the presence or absence of the heat-retaining bag 30.

[0053] As shown in Figure 17, when the insulating bag 30 is present, the soil is cooled to a lower temperature at a greater depth than when the insulating bag 30 is absent, confirming that it is possible to control the soil temperature in an energy-efficient manner. [Industrial applicability]

[0054] The present invention is useful as a soil temperature control system for heating or cooling farm soil, and is particularly suitable as a soil temperature control system that can control soil temperature with energy efficiency while suppressing the maximum energy consumption of the heat source with a simple structure. [Explanation of symbols]

[0055] 1 Strawberry farm 2 cultivation benches 3,3A,3B,3C,3D,3E Heat insulation tube 4 controllers 20 mounting units 21 Cultivation tank 22 straight pipes 23 Synthetic resin sheet 24 Cultivating soil 30 Thermal bag 31 Heater 32,33 Adhesive part 34 Air 35 Aluminum (aluminum) vapor-deposited film 36 Functional Materials 37,38 Cold air pipes 37A,38A cold air 40 CPU 41 Input / Output Interfaces 42 Power circuit breaker 43-1~4 Power switch Blocks B1-B4 H1~H4 Heater

Claims

1. Multiple insulating tubes, each containing an insulating bag to be placed over a block of soil, and a heat source and gas to be placed inside the insulating bag, Control means for turning on and off the heat sources of the plurality of insulation tubes in each block, A soil temperature control system having the following features.

2. In the soil temperature control system according to claim 1, The control means sequentially turns the heat source on and off according to the operating time set for each block, in a soil temperature control system.

3. In the soil temperature control system according to claim 2, The aforementioned operating time is (a) A step of measuring the current temperature in the soil of each block, (b) A process of calculating the temperature difference between the set temperature and the current temperature in the soil of each block. (c) A step of calculating the total temperature difference by summing the temperature differences of each block. (d) A process of dividing the temperature difference of each block by the sum of the temperature differences to calculate the proportion of the energized time for each block. (e) A process of calculating the energizing time for each block by multiplying the ratio of the energizing time for each block by the energizing cycle time, A soil temperature control system set by a process that includes the following steps.

4. In the soil temperature control system according to claim 1 or 2, A soil temperature control system in which the heat source is a heating source, a cooling source, or a heating / cooling source.

5. In the soil temperature control system according to claim 1 or 2, A soil temperature control system having a functional material on either the upper side or the lower side, or both, of the aforementioned heat-retaining bag.

6. In the soil temperature control system according to claim 5, The aforementioned functional material is an aluminum vapor-deposited film, a sheet or film that emits far-infrared rays, or a heat insulating sheet, in a soil temperature control system.

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