JPH0249685B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method and apparatus for controlling a hot water heating system in a greenhouse for greenhouse horticulture.

(2) Background of the technology In greenhouse horticulture, it is important to actively manage temperature in accordance with the ecology of the crops. Such temperature control is performed, for example, by operating a heater using a boiler or utilizing solar heat by a solar system.

However, when using a solar system, the heating effect depends on the weather, and when using a heater, the main energy source is oil, the increase in electricity costs, and the complexity of operation management are taken into consideration. Technology development is being strongly promoted to achieve this goal.

(3) Conventional technology and problems Conventionally, heating in a greenhouse for greenhouse horticulture using a boiler involves installing radiant pipes or a heat exchanger inside the greenhouse, connecting this to the boiler with piping, and connecting hot water to the greenhouse. Systems that perform hot air radiation heating using natural convection or forced draft through heat exchange, or heating systems that perform heating by burying pipes underground and flowing hot water through these pipes have been put into practical use.

In the heating system described above, the boiler's hot water is adjusted according to the heating load (the difference between the outside temperature θo and the indoor control temperature θr; when the difference is large, the load is heavy, and when the difference is small, the load is light). The heating effect may be improved by setting a set temperature, that is, setting it high when the load is heavy, and conversely setting it low when the load is light.

However, the hot water temperature setting is manually changed, and the outside temperature θo fluctuates widely, making it difficult to manage, especially at night, so the actual temperature is left at a constant temperature.

This fact leads to waste of energy such as oil and electricity due to boiler operation beyond necessity.
This is a serious impediment to cost savings. Furthermore, in the case of light loads, the greenhouse temperature fluctuates widely, making it difficult to maintain a constant room temperature.

(4) Purpose of the Invention In view of the above-mentioned conventional problems, the present invention provides a control method and device for a greenhouse hot water heating system that can automatically operate the boiler at an appropriate hot water temperature setting according to the heating load. For the purpose of providing.

(5) Structure of the Invention According to the present invention, the purpose is to provide a method for controlling a hot water heating system in a greenhouse for greenhouse horticulture, with the boiler hot water set temperature being θw, the indoor control temperature being θr, and the outside air temperature being θo. Assuming that the boiler hot water setting upper limit temperature when the air temperature is the lowest temperature θol is θwh, α is determined for the greenhouse using the following formula (θwh−θr)/(θr−θol)=α, and (θw−θr) and (θr−θo hot water in a greenhouse for greenhouse horticulture, characterized in that the boiler hot water set temperature θw is determined from the outside air temperature θo and the indoor control temperature θr so that ) satisfies the following equation (θw−θr)/(θr−θo)=α A heating system control method and a hot water heating system control method in a greenhouse for greenhouse horticulture, where the boiler hot water set temperature is θw, the indoor control temperature is θr, and the outside air temperature is θo, and the boiler hot water is calculated when the outside temperature is the lowest temperature θol. Setting the upper limit temperature to θwh, determine α for the greenhouse using the following formula (θwh−θr)/(θr−θol)=α, and (θw−θr) and (θr−θo) are calculated using the following formula (θw−θr)/ Determine the boiler hot water set temperature θw from the outside air temperature θo and indoor control temperature θr so as to satisfy (θr−θo)=α, and set the upper limit of the boiler safe operating temperature to θwh and the lower limit to θwl.
A method for controlling a hot water heating system in a greenhouse for greenhouse horticulture, characterized in that θw is set so as to satisfy the following equation: θwl≦θw≦θwh. The control device includes an outside air temperature detection means, an indoor temperature detection means, a hot water temperature detection means made of a temperature sensitive resistance element, etc., an indoor control temperature setting means (VR1) made of a variable resistor, etc., and a load factor setting means (VR1) made of a variable resistor etc.
2) is a control device for a hot water heating system in a greenhouse for greenhouse horticulture that uses hot water supplied from a hot water boiler, and the control circuit includes an output of the indoor temperature detection means and an indoor control temperature setting means (VR1). ), a circuit for starting and stopping an indoor heater using the output of the comparison means, an output of the outside temperature detection means, an output of the indoor control temperature setting means (VR1), and a load factor. 2: an arithmetic circuit that calculates the boiler hot water set temperature from the output of the setting means; a means that compares the output of the arithmetic circuit with the output of the temperature detecting means; and a circuit that starts and stops operation of the boiler based on the output of the comparing means. This is achieved by providing a control device for a hot water heating system in a greenhouse for greenhouse horticulture, characterized by having a configuration consisting of a system control circuit.

(6) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a device configuration diagram of the heating system according to the present invention, in which 1 is a load controller and 2 is a
Fully automatic hot water boiler (boiler) with a capacity of 25000Kcal/H to 500000Kcal/H, 5 is a circulation pump,
6 indicates a hot water supply pipe.

The load controller 1 receives input information 4 from three temperature sensing sensors (temperature sensitive resistance elements) and outputs operation start and stop signals to the boiler 2 as output information.

The above three sensors are an outside temperature sensor 7, a greenhouse temperature sensor 8, and a hot water sensor 3 located in the boiler 2, and the load controller 1 is set by the signals from these three sensors and by the user of the heating system. The above output information 4 is given to the boiler 2 based on the greenhouse management temperature and load factor according to the principle described later.

Here, if the hot water setting temperature of the boiler is θw, the indoor control temperature is θr, and the outside air temperature is θo, (θw−θr)
If it is made proportional to (θr - θo), that is, if the energy required for heating (heating load) is made equal to the energy actually used for heating, effective use of energy can be achieved.

In a certain system, if we select α once such that (θw − θr) = α(θr − θo) holds, then in that system, if θr is constant, (θr is the indoor control temperature, so the normal ), θw is determined according to the change in θo.

To determine α for this purpose, one condition is the boiler's maximum hot water temperature θwh when the outside temperature in the area of the system is the lowest θol, and then α is determined. α = (θwh − θr) / ( In that system under conditions different from θr−θol), (θw−θr)=α(θr−
Since θr is constant, θw can be determined in response to changes in θo.

For example, in a greenhouse where the control temperature θr must be 15°C, if the minimum outside temperature is -5°C and hot water of 85°C (hot water setting maximum temperature) is required to achieve the above θr, Under this condition, the load factor α is 3.5 from the formula. If the load factor α is fixed at this value in the greenhouse, the outside temperature will be 5.
℃, the hot water setting temperature θw to achieve the control temperature of 15℃ is 50℃ from the formula. By the way, boilers have a specified hot water temperature range within which they can be operated safely. Now, if the upper limit temperature is θwh and the lower limit is θwl, the hot water set temperature θw is θwl≦θw≦
It is reasonable to set it so that θwh is satisfied.
In the control method of the present invention, when θw is obtained from the formula as a value outside the above range, θw is set to θw>θwh.
It is characterized in that the value of θwh is set when θw<θwl, and the value of θwl is set when θw<θwl.

Figure 2 shows the change in θw mentioned above at different load factors α
In this diagram, the larger the slope of the line shown in the figure, the larger the value of α set. If θw is outside the boiler's safe operating temperature range, θw is kept at the upper and lower limits as shown by the lines.
In this embodiment, θwh is set to 85°C and θwl is set to 50°C, but these values are set as appropriate depending on the performance of the boiler.

Next, the load control circuit will be explained.

FIG. 3 is a circuit diagram of the main part of the load control circuit.
The control circuit can be broadly divided into a power supply section (not shown),
The main parts are the temperature sensor signal detection section shown in Figure a, the hot water setting temperature calculation unit (Figure b),
and other auxiliary circuits (not shown).

The power supply section is intended to supply an appropriate voltage to the signal detection section, and supplies different voltages to the greenhouse temperature and outside air temperature detection section and the boiler hot water temperature detection section, respectively, as will be described later.

Next, the temperature sensing sensor (thermistor) signal detection section shown in Figure a is a circuit that extracts the temperature change of the resistance in the thermistor as a voltage change.It is structurally comprised of a boiler hot water temperature detection section, a greenhouse temperature and outside air temperature detection section. It is divided into

Referring now to Figure 4, this figure is a diagram showing the temperature characteristics of the thermistor, where the horizontal axis represents the temperature of the detection part;
It is known that when the output voltage is plotted on the vertical axis, the temperature characteristic of the thermistor becomes a characteristic curve as shown by curve i in the figure.

The control circuit described above has an analog calculation circuit (linear circuit) that calculates the hot water temperature setting using the output of the thermistor, so the voltage input to this calculation circuit is proportional to the temperature within the required temperature range. There must be. However, the characteristics of the thermistor are
The output voltage deviates from linearity when the boiler hot water temperature exceeds 50°C, so it is necessary to correct the output voltage in this temperature range. In other words, in order to maintain linearity, a circuit is required that outputs the output voltage t1 at 50°C as the value t1' and the value t2 at 85°C as the value t2'.

The detection section of the load control circuit of the present invention is characterized in that different voltages are applied to the hot water temperature and outside air temperature detection section and the boiler hot water setting detection section in order to correct the temperature characteristics described above. Diagram a
Referring to the figure, the part that provides outputs A, B, and C is the greenhouse temperature and outside temperature detector, and the part that provides output D is the boiler hot water detector.
In the former detection section, an appropriate voltage is applied to terminal IN1 from the power supply section, and the greenhouse temperature thermistor is connected to the terminal IN1.
The output voltages of the Tr and the thermistor To for outside temperature are divided by the resistor R1 or R2 and taken out to A and B (all thermistors used in the circuit are of the same standard).

The variable resistor VR1 is a volume for setting the temperature control temperature θr, and thereby provides an output voltage to C that matches the linear characteristic shown in FIG. 4 in accordance with the set temperature θr.

On the other hand, since the boiler hot water temperature detection section corrects the temperature characteristics of the thermistor as described above, a voltage different from that to the terminal IN1 is applied to the terminal IN2. In this way, the hot water temperature detected by the thermistor Tw is taken out to D as a voltage correctly proportional to the temperature.

Next, the calculation section shown in Figure b will be explained.
The circuit calculates the hot water set temperature θw by multiplying the heating load by α and then adding the greenhouse control temperature θr according to the load factor α set by the volume VR2.
When the hot water temperature detected by the detection unit [FIG. 3a] is lower than the above-mentioned θw, an operation start signal is output to the boiler. The voltage corresponding to the greenhouse control temperature θr input to the non-inverting input terminal (+) of the operational amplifier IC1 is made constant by the IC1, and then the amplifier IC
The voltage input to the non-inverting input terminal (+) of No. 2 and the voltage corresponding to the outside temperature θo input to the inverting input terminal (-) is subtracted, and the voltage corresponding to the heating load (θr - θo) is output ( position indicated by C1 in the figure).
This result is processed by the next multiplication (amplification) circuit (IC3).
It is multiplied by α by VR ₂ , and then θr is added by the adder circuit IC5, resulting in a voltage output J corresponding to the hot water set temperature θw. Note that IC4 is an amplifier for making the output C constant voltage, and output I of operational amplifier IC1 is a comparator for controlling the operation of the heater.
Used as input for IC11.

The comparator of this IC11 is a circuit that checks whether the indoor temperature given by the output A is below the control temperature θr. If it is below, the transistor Q1 is turned on and the relay Ry1 is closed. An on/off signal generated by opening and closing this relay Ry1 is given to the heater, and by controlling the operation of the heater, the inside of the greenhouse can be maintained at a controlled temperature.

By the way, the subtraction circuit (IC2) that calculates the heating load mentioned above and the multiplication circuit (IC3) that multiplies the result by α
By separating these, it is possible to create a proportional relationship between the rotation angle of the setting knob and the set value in setting the load factor, which has the effect of facilitating the setting operation.

In this embodiment, the load factor α is appropriately set within the range of 1≦α≦10.

The output J of the hot water set temperature mentioned above is applied to a limit circuit consisting of operational amplifiers IC6 to IC9 shown in detail in Figure c, and it is determined whether the set temperature is within the boiler safe operating temperature range (50℃≦θw≦85℃). be done. Here, if the calculated set temperature θw is within the above range, the input voltage J is output as is, but when θw is 85°C or higher, the voltage equivalent to 85°C is output, and when θw is 50°C or lower, the voltage corresponding to 85°C is output. outputs a voltage equivalent to 50°C.

This limit circuit uses an operational amplifier to correct the bias current (operates even when the bias current is 0) in a limit circuit consisting only of ordinary diodes.
It is characterized by being implemented by IC7 and IC8 (ideal diodes). Note that the amplifier IC7 has a terminal
A voltage (G) corresponding to an upper limit value of 85°C obtained by dividing the voltage applied to IN2 with a resistor R15, a voltage (F) divided by R14 corresponding to a lower limit value of 50°C is input to IC8, and a diode The circuit connected to terminal H through TD1 is a limit circuit protection circuit that prevents output of 2.0V or higher.

In terms of operation, in Figure 3c, when the voltage of J is G>J>F, IC7 and IC8 operate as comparators, so the diodes HD2 and TD
3 is reverse biased and in an off state, so the input voltage J is outputted as the output voltage K as it is.

When the voltage J>G, the output of IC7 is turned off,
Diode TD2 is turned on to prevent the voltage at point L, which is the intersection of the line connecting R17 and R18 and the line passing through diode TD1 to point H, from rising.
Current flows through TD2 and R17.

When the voltage J<F, the output of IC8 turns on,
Diode TD3 is turned on, and current flows through TD3 and R17 so that the voltage at point L does not drop. From the above, the voltage at the L terminal is maintained as G>L>F,
After passing through the IC9 buffer, G>K>F.

The hot water set temperature information limited to the range of 50°C to 85°C by the above limit circuit is input to the non-inverting input terminal of a comparator consisting of an operational amplifier IC10, and the comparator determines that the hot water temperature detected by the thermistor Tw is , check whether the hot water temperature is below the set temperature θw. As a result, if it is less than θw, transistor Q2 is turned on, relay Ry2 is closed, and an operation start signal is output to the boiler.

Note that hot water temperature rises due to boiler operation,
When Qw (≦85℃) is exceeded, the transistor Q
2 is turned off, relay Ry2 opens and the boiler stops.

In addition, by adding an electrolytic capacitor CD installed in front of the limit circuit shown in the same figure, it is possible to prevent the output of the calculation circuit from being disturbed when the outside temperature To changes extremely minutely due to external disturbances. prevents the boiler from turning on and off stably.

In other words, when there is a minute change in the outside temperature θo,
This change is converted into a change in resistance by the thermistor To, and then into a minute change in voltage (high frequency) within the circuit. At this time, capacitor CD functions as a low-pass filter that removes high-frequency components of the voltage.

Reference is now made to FIG. The figure is a diagram showing the temperature characteristics of the load control circuit at different load factors. The horizontal axis shows the heating load (θr - θo) (deg), the vertical axis shows the hot water set temperature θw (deg), and the outside air temperature θo is 0℃
Fixed.

Referring to the same figure, each characteristic curve at different load factors α from 1 to 10 has θw controlled to a value within the boiler's safe operating temperature, and is almost a straight line within that range, and the input and output of the circuit are This shows that the relationship is linear.

By the way, the values of each element in the load control circuit described above are not limited to the values shown in this example.
Change as necessary. For example, Volume VR1
Also, change the VR2 setting range, or change the safe operating temperature range as appropriate to match the boiler you are using.

FIG. 6 shows an application example of this embodiment, in which the same parts as in FIG. 1 are denoted by the same reference numerals. Referring to the figure, a heat exchange type heater 10 between hot water and indoor space is connected to a load controller 1, and the operation of the heater 10 is controlled by the heater operation signal 9 of the load control circuit described above. It is a system. Further, the on/off of the circulation pump 5 that sends hot water to the heater 10 can be controlled in conjunction with the on/off of the heater.
Heating efficiency can be improved.

(7) Effects of the Invention As described above in detail, the present invention provides a heating system and its load control device that can automatically control the operation of an appropriate boiler according to the heating load. Because you can
There is no need to manually set the boiler hot water temperature, a stable greenhouse temperature control can be achieved, and fuel savings can be achieved through safe and efficient boiler operation.

[Brief explanation of drawings]

FIG. 1 is a device configuration diagram of the heating system of the present invention,
Fig. 2 is a diagram showing the temperature characteristics for different load factors, Fig. 3 is a load control circuit diagram, Fig. 4 is a diagram showing the temperature characteristics of the thermistor, and Fig. 5 is a diagram showing the temperature characteristics of the above load control circuit. The diagram and FIG. 6 are device configuration diagrams of a heating system showing an application example of the present invention. 1...Load controller, 2...Fully automatic hot water boiler, 3
...Hot water temperature sensor, 4...Output information, 5...Circulation pump, 6...Piping, 7...Outside temperature sensor, 8...Greenhouse temperature sensor, 10...Heater (heat exchange type heater between hot water and indoor space) ), R1-R2
0...Resistance, IC1...IC11...Operation amplifier, Q1,
Q2...transistor, RY1,RY2...relay,
To, Tr, Tw...Thermistor.

Claims (1)

[Claims] 1. A method for controlling a hot water heating system in a greenhouse for greenhouse horticulture, in which the boiler hot water set temperature is set to θw,
Determine α for the greenhouse using the following formula (θwh−θr)/(θr−θol)=α, where the indoor control temperature is θr, the outside air temperature is θo, and the boiler hot water setting upper limit temperature when the outside temperature is the lowest temperature θol is θwh. Then, determine the boiler hot water set temperature θw from the outside air temperature θo and indoor control temperature θr so that (θw−θr) and (θr−θo) satisfy the following formula (θw−θr)/(θr−θo)=α A method for controlling a hot water heating system in a greenhouse for greenhouse horticulture, characterized by: 2. As a control method for a hot water heating system in a greenhouse for greenhouse horticulture, the boiler hot water setting temperature is set to θw,
Let the indoor control temperature be θr, the outside air temperature be θo, and let the boiler hot water setting upper limit temperature be θwh when the outside air temperature is the minimum temperature θol. The boiler hot water set temperature θw is determined from the outside air temperature θo and the indoor control temperature θr so that (θw−θr) and (θr−θo) satisfy the following equation (θw−θr)/(θr−θo)=α. Determine the upper limit of boiler safe operating temperature as θwh and the lower limit as θwl.
A method for controlling a hot water heating system in a greenhouse for greenhouse horticulture, characterized in that θw is set so as to satisfy the following equation: θwl≦θw≦θwh. 3. A control device for a hot water heating system in a greenhouse for greenhouse horticulture, which includes an outside temperature detection means 7 consisting of a temperature-sensitive resistance element, an indoor temperature detection means 8, a hot water temperature detection means 3, and an indoor temperature control consisting of a variable resistor, etc. A control device for a hot water heating system in a greenhouse for greenhouse horticulture that uses hot water supplied from a hot water boiler, which is equipped with a setting means (VR1) and a load factor setting means (VR2), wherein the control circuit includes the indoor temperature detection circuit. In addition to the means for comparing the output of the means 8 and the output of the indoor control temperature setting means (VR1), a circuit for starting and stopping an indoor heater based on the output of the comparing means, and the output of the outside air temperature detecting means 7, Indoor control temperature setting means (VR
an arithmetic circuit for calculating the boiler hot water set temperature from the output of 1) and the output of the load factor setting means; a means for comparing the output of the arithmetic circuit with the output of the hot water temperature detecting means 3; 1. A control device for a hot water heating system in a greenhouse for greenhouse horticulture, characterized in that it has a configuration consisting of two control circuits, one for starting and stopping the operation of the second circuit.