JPS5814682B2 - temperature control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature control device suitable for a greenhouse, and more particularly to a temperature control device for a greenhouse that can control the temperature of hot water in a hot water heater based on outside temperature, sunlight, wind speed, wind direction, etc. It is something.

For example, hot water heaters are currently used as greenhouse heaters for growing crops such as fruits and vegetables.

In this system, pipes are installed underground or in the air inside the greenhouse, and hot water heated to a certain temperature flows through the pipes to heat the greenhouse.

By the way, a temperature control device is used to control the temperature inside the greenhouse, and this device generally generates a command signal for heating when the temperature inside the greenhouse becomes lower than a set value.

In addition, when such a temperature control device is used to control the temperature of a hot water heater, hot water is flowed through the pipe while the heating command signal is being generated, and the temperature in the greenhouse is maintained at the set value. The room temperature is controlled by stopping the flow when the heating command signal is cut off.

As a conventional temperature control device of this kind, one shown in FIG. 1 has been proposed.

In FIG. 1, resistors 2, 3, 4, and 5 constituting a bridge circuit 1 are connected between a power source 8 and the ground.

A variable resistor 6 for setting the room temperature is connected between the resistors 2 and 3, and a temperature sensing element 7 such as a thermistor is connected in parallel to the resistor 4. It is installed in an object whose temperature is to be adjusted, for example, a greenhouse, and detects the room temperature thereof.

The output end of the bridge circuit 1, that is, the connection point between the sliding terminal of the variable resistor 6 and the resistors 4 and 5 is connected to a comparator circuit 8 via a resistor, respectively.

The output side of the comparator circuit 8 is connected to the base of a transistor 9, the emitter of this transistor 9 is grounded, and the collector is connected via a relay 10 to a relay power supply Vd.

The relay 10 has a relay contact 11, and this relay contact 1
1 is closed, the hot water valve 13 is opened by the power source 12 for the hot water valve, and hot water is supplied into the greenhouse through a pipe (not shown).

Now, assuming that the temperature in the greenhouse is at a predetermined temperature set by the variable resistor 6, the bridge circuit 1 is in an equilibrium state, and the potential between the sliding terminal of the variable resistor 6 and the ground, that is, the set voltage E1 and the potential E2 across the resistor 5 are equal, so the output of the comparator circuit 8 is zero.

When the temperature inside the greenhouse decreases, the resistance value of the thermistor I increases, and the terminal voltage E2 of the resistor 5 decreases.

Therefore, since the set voltage E1 becomes larger than the terminal voltage E2, the equilibrium state of the bridge circuit 1 is lost, and an output proportional to the difference between the voltages E and E2 is generated on the output side of the comparator circuit 8.

This output is supplied to the transistor 9 as a heating command signal to make it conductive, thereby energizing the relay 10 and closing the relay contact 11.

As a result, the hot water valve 12 opens, hot water is supplied into the greenhouse, and the temperature inside the greenhouse begins to rise gradually.

As the temperature inside the greenhouse increases, the resistance value of the thermistor 7 decreases, and conversely, the terminal voltage E2 of the resistor 5 increases.

When this terminal voltage E2 becomes equal to the set voltage E1 again, the output of the comparator circuit 8 becomes zero, so that the transistor 9 becomes non-conductive, the relay 10 is deenergized, the hot water valve 13 is closed, and water is supplied to the greenhouse. will be stopped.

Such operations are repeated in response to temperature changes within the greenhouse.

Note that the comparator 8 is configured so that its output becomes zero when the room temperature is equal to or higher than the set temperature, so that when the room temperature is higher than the set temperature, hot water is not supplied to the greenhouse. It is constantly being stopped and corrected.

However, the conventional temperature control device having such a configuration has a problem in that the temperature inside the greenhouse is significantly influenced by the environment in which the greenhouse is located, such as the outside temperature and the amount of sunlight.

In other words, the temperature of hot water flowing during normal heating is, for example, 1
The temperature is maintained at a constant temperature using a boiler, such as 80°C in February and 90°C in January.

The temperature of the greenhouse is then set and controlled, but when the outside temperature is high or low depending on the day,
When the amount of sunlight is high or low, variations occur in the time it takes for the temperature inside the greenhouse to reach the set temperature and the time it takes for the greenhouse to cool down.

In other words, when the difference between the outside temperature and the set temperature is small, the temperature will not rise easily due to the residual heat of the high-temperature hot water that remains in the pipes even if the mission signal for heating is stopped, and the greenhouse temperature will be lower than the set temperature. The average temperature of the area becomes high.

Therefore, when the difference between the outside temperature and the set temperature is small, 8
Hot water of 0°C to 90°C is unnecessary, wastes fuel, and is also unfavorable for crops, especially crops near hot water pipes, which may suffer from high temperature damage.

The same thing can also be said when there is a lot of sunlight.

The present invention has been made in view of these points, and
The present invention provides a temperature control device that can control the temperature inside a greenhouse in response to changes in the environment in which a temperature-adjusted object, such as a greenhouse, is placed, such as changes in outside temperature and solar radiation.

Embodiments of the present invention will be described in detail below with reference to FIG.

In Fig. 2, parts corresponding to those in Fig. 1 are given the same reference numerals, and their detailed explanations are omitted.1 In the example in Fig. 2, resistors 15, 16, and 17 are further connected between the power supply, B, and ground. , these resistors, resistors 2 and 3, and variable resistor 6 constitute a second bridge circuit 18.

A detector for detecting the outside temperature, for example a humidity sensing element 19 such as a thermistor, is connected in parallel to the resistor 15, and a detector for detecting the temperature of water in a boiler (not shown) is connected to the resistor 16. , moisture sensing elements 20, such as, for example, Thermisk, are connected in parallel.

Further, the thermistor 19 is connected to a protective tube 14 provided around it.
The outside of this protective tube has a color that easily absorbs sunlight.
For example, paint it black or gray.

Therefore, the thermistor 19 can detect the outside temperature as well as the amount of sunlight.

The output end of the bridge circuit 18, that is, the connection point between the sliding terminal of the variable resistor 6 and the resistors 16 and 17 is connected to a comparison circuit 21 similar to the comparison circuit 8 through the respective resistors.

The output side of the comparison circuit 21 is connected to the base of a transistor 22, and the emitter of this transistor 22 is grounded.
The collector is connected to a relay power supply Vd via a relay 23.

The relay 23 has a relay contact 24, and this relay contact 2
The burner 26 is ignited by the Yoshi burner power supply 25 when the burner 4 is closed, and the hot water in the boiler is heated.

Next, the operation of the temperature control device according to the present invention will be explained.

First, the relationship among the outside temperature, the amount of sunlight, the set temperature in the greenhouse, and the boiler water temperature at that time can be roughly expressed by the following equation.

X~A(c-a)-B-b...(1) In this example, X is the boiler water temperature (℃), a is the outside temperature (℃), b is the amount of sunlight, and C is the set temperature (℃). , A is a constant determined by the greenhouse shape, heating capacity, and piping method, and B is a correction coefficient for converting the amount of sunlight into a temperature rise in the greenhouse.

From the above equation (1), it can be seen that the hot water temperature X changes depending on the outside temperature a and the amount of sunlight b, assuming that the set temperature C is constant.

Conversely, this means that by adjusting the hot water temperature X, changes in the outside temperature a and the amount of sunlight b can be offset, thereby making it possible to always maintain the temperature inside the greenhouse at a constant temperature.

In FIG. 2, if the temperature in the greenhouse is now set to the set temperature and the amount of sunlight and the outside temperature are constant, bridge circuits 1 and 18 are both in an equilibrium state, and the sliding terminal of variable resistor 6 and the ground The potential between them, that is, the set voltage E1 and the voltage E3 across the resistor 17 are equal, so the output of the comparator circuit 21 is zero.

As the outside temperature drops, the resistance value of the thermistor 19 increases, and the terminal voltage E3 of the resistor 17 decreases.

Therefore, since the set voltage E1 becomes larger than the terminal voltage E3, the equilibrium state of the bridge circuit 18 is disrupted, and the comparator circuit 21
An output proportional to the difference between voltages E1 and E2 is generated on the output side.

This output is supplied as a command signal for heating to the transistor 22 to make it conductive, thereby energizing the relay 23 and closing the relay contact 24.

As a result, the burner 26 of the boiler is ignited by the power source 25 to increase the temperature of the water in the boiler.

Normally, the temperature inside a greenhouse is set to about 15-20℃ at night and about 20-30℃ during the day, which is higher than the outside temperature, so hot water is not used until the temperature inside the greenhouse reaches the set temperature. Valve 13 is in an open state.

Therefore, the hot water heated in the boiler as described above is supplied into the greenhouse through the pipe.

Further, since the boiler water temperature is detected by the thermistor 20, the resistance value of the thermistor 20 decreases as the water temperature increases, and conversely, the terminal voltage E3 of the resistor 17 increases.

When the terminal voltage E3 becomes equal to the set voltage E1, the output of the comparator circuit 21 becomes zero, and the relay 23 is deenergized and the burner 26 is extinguished.

Such operations are repeated in response to changes in outside temperature.

Therefore, low-temperature hot water is supplied into the greenhouse when the outside temperature is high, and high-temperature hot water is supplied through the pipe when the outside temperature is low.

Next, if the amount of sunlight changes, the amount of calories absorbed by the protection tube 14 of the thermistor 19 will change, so the resistance value of the thermistor 19 will also change according to this change, and the same operation as in the case of the outside temperature described above will be repeated. The water temperature in the boiler is controlled.

In this way, the boiler water temperature is controlled by the thermistors 19 and 20, but since these thermistors 19 and 20 are connected in series to one side of the bridge circuit 18 as described above, their combined output controls the temperature of the boiler. The initial objective will be achieved by controlling the water temperature.

As is clear from the above description, according to the temperature control device according to the present invention, hot water can be supplied into the temperature-adjusted object according to changes in the environment around the temperature-adjusted object, such as the outside temperature and the amount of sunlight. By configuring the boiler to adjust the hot water temperature in the boiler, there is no need to heat the boiler to maintain a constant hot water temperature like in conventional equipment, and the boiler water temperature changes according to changes in outside temperature and amount of sunlight. As you can adjust the firing level of the boiler, you can not only save fuel, but also adjust the temperature accurately and sensitively to changes in outside temperature, amount of sunlight, etc.
It is possible to provide an optimal environment for crops grown in a temperature-controlled object such as a greenhouse.

In addition, although the above-mentioned example explained the case of a greenhouse for growing crops as the temperature-controlled object, it is not limited to this, and can be applied to other objects and places used in the above-mentioned environment. Needless to say, the same effect can be obtained.

In addition, the protection tube 14 of the thermistor 19 is painted on the outside to absorb sunlight, or its shape is configured so that it is affected by wind force and wind direction.
It may also be possible to detect not only outside temperature and amount of sunlight but also wind force and wind direction.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional temperature control device, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. In the figure, 1 and 18 are bridge circuits, 7, 19.20 are thermistors, 8 and 21 are comparison circuits, 10.23 are relays, 1
3 is a hot water valve, 14 is a protection tube, and 26 is a burner.

Claims (1)

[Claims] 1. Temperature control that detects the room temperature, compares the detected value with a room temperature set value, and adjusts the hot water valve according to the comparison output to control the amount of hot water supplied into the room. In the device,
a first detector for detecting the outside air depth and the amount of sunlight;
a second detector for detecting the water temperature of the boiler; a comparison means for comparing the output obtained by weighing the outputs of the first and second detectors with the room temperature set value; and a comparison means according to the output of the comparison means. and a relay means for controlling the burner for the boiler, the temperature adjusting device being characterized in that the temperature of the hot water in the boiler is adjusted according to changes in outside temperature and the amount of sunlight. 2. The temperature control device according to claim 1, wherein the first detector comprises a temperature sensing element and a protection tube provided around the temperature sensing element to sense sunlight.