JP2017225415A - Method and apparatus for detecting snow cover on greenhouse roof as well as method and apparatus for melting snow on greenhouse roof using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means for detecting snow cover which enables snow melting with a low loss of snow melting energy by detecting the presence or absence of snow cover on a greenhouse roof inexpensively, accurately, and extensively.SOLUTION: In detecting snow cover of a greenhouse roof 14 in which temperature is managed by a heating device, the inner surface temperature (the surface temperature of a greenhouse side) of the greenhouse roof 14 is measured by a temperature sensor 40, and when the change of the inner surface temperature of the greenhouse roof 14 which is measured by the temperature sensor 40 is within a given threshold range including 0°C, it is detected that there is snow cover on the greenhouse roof 14. When the temperature sensor 40 is disposed at a plurality of positions and the number of the temperature sensors 40 indicating a value within the given threshold range is not less than a given number, it can be detected that there is snow cover.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a method and apparatus for detecting snow accumulation in a greenhouse roof, and a method and apparatus for melting snow in a greenhouse roof using the same, and more particularly to a greenhouse roof suitable for use in a greenhouse for cultivation placed in a snowfall area. The present invention relates to a snow cover detection method and apparatus, and a snow melting method and apparatus for a greenhouse roof using the same.

  In general, a greenhouse for cultivating plants such as vegetables, fruits and flowers needs to receive more sunlight, and therefore, as illustrated in FIG. The inside of the greenhouse 10 which is formed by covering with the vinyl roof 14 and the vinyl side plate 16 and covered with the vinyl roof 14 and the vinyl side plate 16 is always temperature-controlled by a heating device such as a warm air heater. However, if it is a single building, the snow piled up on the vinyl roof 14 naturally falls to the side of the building, but especially in the greenhouse 10 (three buildings in the figure) as illustrated in FIG. The snow piled up on the vinyl roof 14 between the buildings will not fall and accumulate. For this reason, there has been a problem that the greenhouse 10 collapses without being able to withstand a snow load when a large amount of snow falls.

  Therefore, conventionally, a snow melting device 20 including a hot water boiler 22 is provided, and hot water is allowed to flow from the hot water boiler 22 to a snow melting pipe 24 provided in a valley portion between each building, and the melted snow is collected by a firewood 26. It was.

  In the figure, reference numeral 42 denotes a container house in which a controller 44 and the like for controlling the heating device and the snow melting device 20 are accommodated.

  In order to operate the snow melting apparatus as described above, it is necessary to detect snow accumulation. For example, Patent Document 1 describes that snow accumulation is detected based on distortion of a greenhouse due to the weight of snow accumulation.

  Moreover, although it is not for greenhouse roofs but for general use such as houses and roads, (1) an optical snowfall sensor that detects snow accumulation from the reflection of light when an LED or laser is irradiated into the atmosphere has been put into practical use, (2) Contact sensors that measure physical quantities such as electrical resistance and dielectric constant, (3) Non-contact sensors that use laser, microwave, ultrasonic reflection, etc., and (4) Image processing taken with a camera. A snow cover sensor is also considered.

Japanese Patent Laid-Open No. 5-123061

  However, the method for detecting the distortion of the greenhouse described in Patent Document 1 cannot detect snow until the distortion occurs in the greenhouse, and detection delay may be a problem.

  Also, the optical snowfall sensor (1) detects reflections from falling snow in the atmosphere, so it detects small amounts of snow that naturally melts with little snow and wet snow close to rain. The actual snow cover cannot be detected, the snow melting device is turned on before the snow is piled up, and the snow melting device is turned off after the time from when the snow stops and the snowfall sensor is turned off until the snow is completely melted. The loss of snow melting energy is large.

  In addition, the method (2) using the electric resistance and dielectric constant can be inexpensive, but it is difficult to discriminate between water (rain) and snow, and the possibility of malfunction is high. It becomes measurement.

  Further, the method (3) using laser, microwave, ultrasonic reflection or the like is expensive and has a narrow measurement range.

  In addition, the method (4) based on image processing is wide and inexpensive, but has many problems such as many misjudgments due to image processing, software development, and maintenance.

  The present invention has been made to solve the above-mentioned conventional problems, and has as its first object to make it possible to detect the presence or absence of snow at a low cost accurately and over a wide range.

  Another object of the present invention is to enable snow melting with a small loss of snow melting energy.

  In the present invention, when detecting a snow cover of a greenhouse roof whose temperature is controlled by a heating device, the inner surface temperature of the greenhouse roof is measured by a temperature sensor, and the change in the inner surface temperature of the greenhouse roof measured by the temperature sensor is 0 ° C. The first problem is solved by detecting that there is snow on the roof of the greenhouse when it is within a predetermined threshold.

  In addition, in this invention, the internal surface temperature of a greenhouse roof is the greenhouse side surface temperature of a greenhouse roof.

  Here, it is possible to detect that there is snow when the temperature sensors are arranged at a plurality of positions and the number of temperature sensors within the predetermined threshold is equal to or greater than a predetermined number.

  Also, the predetermined number for detecting the presence of snow can be increased, and the predetermined number after detection can be decreased to make it difficult to detect the absence of snow.

  In the present invention, when melting snow on a greenhouse roof, by starting snow melting when detecting the presence of snow in the above-described greenhouse roof snow detection method, and ending snow melting when no snow is detected, This solves the second problem.

  The present invention is also a snow detecting device for a greenhouse roof whose temperature is controlled by a heating device, a temperature sensor for measuring an inner surface temperature of the greenhouse roof, and a change in the inner surface temperature of the greenhouse roof measured by the temperature sensor. Means for detecting that there is snow on the roof of the greenhouse when the temperature is within a predetermined threshold across 0 ° C., which solves the first problem by a snow cover detection device for a greenhouse roof, is there.

  The present invention also provides a snow melting means for melting the snow on the greenhouse roof, and when the snow melting detection device detects the presence of snow on the greenhouse roof, The second problem is solved by a snow melting device for a greenhouse roof comprising a controller for terminating snow melting by the snow melting means.

  According to the present invention, it is possible to accurately detect the presence or absence of snow cover at a low cost and in a wide range. Therefore, it is possible to reliably prevent the collapse of the greenhouse due to snow accumulation and to install the greenhouse in the snowfall area.

The perspective view which shows an example of the greenhouse for cultivation which is the application object of this invention Front view showing an example of a sheet type thermocouple as a temperature sensor The top view of FIG. 1 which shows the example of the arrangement position of a temperature sensor Sectional drawing of the vicinity of the eaves 26 similarly showing an example of the arrangement state The figure which shows the roof inner surface temperature measurement result of the greenhouse roof center Figure showing an example of the relationship between the temperature inside the greenhouse and the temperature inside the roof of the greenhouse when there is snow Sectional view for explaining the principle of the present invention The flowchart which shows the procedure of the snow cover detection process in embodiment of this invention The figure which shows the processing result by temperature sensor output

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the content described in the following embodiment and an Example. In addition, the constituent elements in the embodiments and examples described below include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in the so-called equivalent range. Furthermore, the constituent elements disclosed in the embodiments and examples described below may be appropriately combined or may be appropriately selected and used.

  First, the principle of the present invention will be described.

  In order to confirm the principle of the present invention, as shown in FIG. 2, for example, a temperature sensor 40 composed of a sheet-type thermocouple in which a thermocouple element is covered with a SUS thin film having a square shape with a side of 25 mm and a thickness of 0.2 mm. As shown in FIG. 3, these were arranged in each part of the greenhouse, and the inner surface temperature Tr, the indoor temperature Ti, the armpit temperature Tg, and the outdoor temperature To of the vinyl roof 14 were measured. The numbers 2, 3, 4, and 5 after the inner surface temperature Tr indicate the roof number, the subscript a indicates the center of the eaves, and the subscript b indicates the end of the eaves. In FIG. 3, reference numerals 34 and 36 denote large and small hot air heaters arranged in each building.

  Here, the temperature sensor 40 for measuring the inner surface temperature Tr of the vinyl roof 14 may be disposed on the entire surface of the roof, but in FIG.

  The measurement result of the inner surface temperature Tr5a at the center of the roof number 5 of the vinyl roof 14 of the greenhouse 10 is shown in FIG. As is apparent from the figure, it is understood that the measured temperature is in a narrow range with 0 ° C. sandwiched between snow.

  FIG. 6 shows an example of the relationship between the temperature in the greenhouse and the temperature inside the roof of the greenhouse during snow. It can be seen that even if the temperature in the greenhouse changes in the range of 5 to 15 ° C., the roof inner surface temperature is in the range of about −1 to + 1 ° C. This is because, as shown in FIG. 7, for example, the contact surface of the snow cover 6 is melted by the surface of the vinyl roof 14 that is maintained at about +5 to 10 ° C. by a hot air heater to become melt 8. Conceivable. The present invention has been made based on such knowledge.

  In the embodiment of the present invention, as shown in FIG. 3, eight temperature sensors Tr2a, Tr2b, Tr3a, Tr3b, Tr4a, Tr4b, Tr5a, Tr5b are arranged on the greenhouse side surface of the vinyl roof 14 and measured. According to the result, the snow melting device 20 was controlled by the controller 44 arranged in the container house 42 shown in FIG.

  Specifically, as shown in FIG. 8, first, at step 100, the temperature Tp of each point is measured at a sampling time Δt = 1-5 seconds, and at step 110, the temperature measurement points p = 1-8 are respectively calculated and processed. If the temperature Tp at that point is within a temperature threshold Ts (eg, ± 1 ° C.), the number N of detected signals is counted up to N + 1.

  Then, the process proceeds to step 120. When the number N of detected signals is less than the threshold value NL (for example, 4 to 8), the process proceeds to step 140, where it is determined that there is no snow and the snow melting device 20 is kept off.

  On the other hand, when the number N of detected signals is equal to or greater than the threshold value NL, the routine proceeds to step 150, where it is determined that there is snow and the snow melting device 20 is turned on.

  FIG. 9 shows the temperature calculation and the pseudo signal processing result. The states other than the lower right in FIG. 9 indicate a state where the temperature is 1 when the temperature at each point is equal to or lower than the temperature threshold, and 0 when not. The lower right indicates the total value. In the embodiment, the threshold NL = 8 is ON, and a small amount of snow that does not require a snow melting device is not detected, and malfunction due to temperature change can be suppressed.

  It should be noted that the threshold value NL is made small when detecting the presence of snow, and hysteresis is provided. At the start of snow accumulation, the snow melting device 20 is difficult to turn on, and after having accumulated to some extent, the snow melting device 20 is turned on. The snow melting device 20 can be turned off after the snow melts. Instead of changing the value of the threshold NL, a time delay step 130 may be added as shown by a broken line in FIG.

  In the present embodiment, since the temperature sensors 40 are provided at eight locations, a wide range of measurement is possible. In addition, the number of the temperature sensors 40 is not limited to this, For example, one may be sufficient. When it is desired to provide a single hysteresis, it is possible to change not only the threshold NL for the number of detected signals N but also the threshold for the number of detections or the temperature threshold Ts.

  In the above embodiment, the malfunction is suppressed by changing the threshold value NL. However, for example, a judgment condition that the outside air temperature is within a range where snow is conceivable, for example, + 4 ° C. or less, or the outside air temperature is not constant. It is also possible to add a determination condition that the user

  The temperature sensor is not limited to a sheet type thermocouple.

6 ... Snow cover 8 ... Melted water 10 ... Greenhouse 14 ... Vinyl roof 20 ... Snow melting device 22 ... Hot water boiler 24 ... Snow melting pipe 26 ... Firewood 34, 36 ... Hot air heater 40 ... Temperature sensor 44 ... Controller

Claims (8)

When detecting snow on a greenhouse roof where the temperature is controlled by a heating device,
Measure the internal temperature of the greenhouse roof with a temperature sensor,
A method for detecting a snow cover on a greenhouse roof, comprising detecting that there is snow on the greenhouse roof when a change in an inner surface temperature of the greenhouse roof measured by the temperature sensor is within a predetermined threshold across 0 ° C.   2. The greenhouse roof according to claim 1, wherein the temperature sensors are arranged at a plurality of positions, and when there is a predetermined number or more of temperature sensors within the predetermined threshold, it is detected that there is snow. Snow detection method.   The method according to claim 2, wherein the predetermined number for detecting the presence of snow is increased, and the predetermined number after detection is decreased to make it difficult to detect the absence of snow. When melting snow on the greenhouse roof,
The snow melting on a greenhouse roof is characterized in that the snow melting is started when snow is detected by the method for detecting snow accumulation on a greenhouse roof according to any one of claims 1 to 3, and the snow melting is terminated when no snow is detected. Method. A snow cover detection device for greenhouse roofs that is temperature controlled by a heating device,
A temperature sensor for measuring the inner surface temperature of the greenhouse roof;
Means for detecting the presence of snow on the greenhouse roof when the change in the inner surface temperature of the greenhouse roof measured by the temperature sensor is within a predetermined threshold across 0 ° C .;
A snow cover detection device for a greenhouse roof characterized by comprising:   6. The temperature sensor is disposed at a plurality of positions, and when there is a predetermined number or more of temperature sensors that are within the predetermined threshold, it is detected that there is snow. Snow cover detector for greenhouse roof as described in 2.   7. The greenhouse roof snow detection apparatus according to claim 6, wherein the predetermined number for detecting presence of snow is increased, and the predetermined number after detection is decreased to make it difficult to detect the absence of snow. Snow melting means for melting snow on the greenhouse roof;
8. A controller that starts snow melting by the snow melting means when detecting the presence of snow with the snow detecting device for a greenhouse roof according to claim 5, and ends the snow melting by the snow melting means when detecting no snow accumulation. When,
A snow melting device for a greenhouse roof characterized by comprising: