JPH0882431A - Cooling/heating mode automatic changeover device for air conditioner - Google Patents

Abstract

PURPOSE: To prevent cooling/heating from being frequency and repeatedly changed over and ensure stable automatic changeover of cooling and heating modes. CONSTITUTION: In a cooling/heating mode automatic changeover device in which there are automatically changed over a cooling mode where an air conditioner is cooling-operated and a heating mode where the air conditioner is heating- operated, there are provided ground temperature measurement means 17 for measuring the earth temperature of the area of which the temperature is controlled by the air conditioner and operation mode alteration means 16 for changing over the heating and cooling mode of the air conditioner on the basis of the earth temperature measured by the earth temperature measurement means 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling / heating mode automatic switching device for a cooling / heating air conditioner provided in a greenhouse or the like.

[0002]

2. Description of the Related Art Air conditioners used for heating and cooling greenhouses are
A cooling operation or a heating operation is performed according to a cooling / heating mode indicating heating. Conventional air conditioners are roughly classified into two types, one that manually switches the cooling / heating mode and one that automatically switches depending on the environmental temperature.

FIG. 6 shows an example of an air conditioner for manually switching the cooling / heating mode. As shown in the figure, the user is configured to select, from the operation mode input unit 1 of the air conditioner, whether to perform the heating operation or the cooling operation of the air conditioner.

When the cooling mode is designated by the operation mode input unit 1, the cooling condition unit 2 judges the start / stop of the cooling operation by comparing the set value (SV) with the actual temperature (T).
The cooling condition unit 2 outputs a cooling start signal to the cooling operation unit 3 when the actual temperature (T) is higher than the set temperature (SV), and the actual temperature (T) becomes the set temperature (SV). When the temperature falls below that, an operation stop signal is output to the cooling operation unit 3.

When the heating mode is designated by the operation mode input unit 1, the heating condition unit 4 judges the start / stop of the heating operation by comparing the set value (SV) with the actual temperature (T).
That is, the heating condition unit 4 outputs a heating start signal to the heating operation unit 5 when the actual temperature (T) is lower than the set temperature (SV), and the actual temperature (T) is set to the set temperature (SV). When it reaches, the operation stop signal is output.

The cooling condition unit 2 and the heating condition unit 4 are
In order to prevent the control signal from being output frequently, once the signal is output, if it is heating, the heating operation is continued until the measured value falls below the set value by a certain temperature (hysteresis). .

FIG. 7 is a diagram showing an example of operation by the automatic switching system of the cooling / heating mode. In case of cooling, the set value (S
V) plus a large amount of hysteresis is set as the cooling set value Sa, and when the actually measured temperature exceeds the cooling set value Sa, a cooling operation signal is output, and cooling is performed to a temperature Sa 'obtained by subtracting a small amount of hysteresis from the cooling set value Sa. The operation signal is continuously output.

In the case of heating, the temperature obtained by subtracting a large amount of hysteresis from the set value (SV) is set as the heating set value Sb, and when the actually measured temperature is lower than the heating set value Sb, a heating operation signal is output and the heating set value Sb is set. The heating operation signal is continuously output up to the temperature Sb 'from which a small amount of hysteresis is subtracted.

By the way, in the above-described method of manually switching the cooling / heating mode, since the cooling operation and the heating operation can be switched for the first time by the user's manual operation, the operation mode is set to the heating mode even when the cooling operation should be performed. If it is in the mode, cooling will not be performed. Conversely, if the operation mode is the cooling mode even when the heating operation should be performed, the heating operation may not be performed. Therefore, if the user forgets to switch the mode or if the operation mode is set incorrectly, there is a possibility that the inappropriate operation of the air conditioner will be performed.

Further, in the above-mentioned automatic switching mode of the cooling / heating mode, there is a high possibility that cooling / heating will be frequently repeated depending on how to take hysteresis. For example, in FIG.
If the hysteresis is set to be small, the set temperature difference between the cooling set value Sa and the heating set value Sb becomes small. When the measured temperature exceeds the cooling set value Sa, the cooling operation is started, and when the temperature becomes lower than the temperature Sa 'defined by the small hysteresis, the cooling is stopped. However, even if the cooling is stopped, the actually measured temperature may further decrease due to the residual heat (cold heat) of the air conditioner and fall below the heating set value Sb. In such a case, heating will be started this time. As a result, the heating is stopped when the measured temperature reaches the temperature Sb 'with a small amount of hysteresis. However, even if the heating is stopped, the actually measured temperature further rises due to the residual heat (warm heat) of the air conditioner, and when it rises above the cooling set value Sa, cooling is restarted.

As described above, by reducing the magnitude of the hysteresis, there is a possibility that the operating state of the air conditioner may fall into a situation in which cooling and heating are repeated alternately. In order to avoid such a problem, the size of the hysteresis is set to be large and the difference between the cooling setting value Sa and the heating setting value Sb is set to be large so that switching between cooling and warming does not occur frequently. There is. However, increasing the amount of hysteresis is
This is not preferable because it reduces the controllability with respect to the set value SV. Frequent switching between cooling and heating causes an unstable refrigerant state, which causes a failure of the compressor.

[0012]

As described above, in the conventional automatic switching device for the cooling / heating mode, there is a high possibility that the cooling / heating is frequently repeated depending on how the hysteresis is taken.
There were problems such as causing an unstable refrigerant state and causing a compressor failure.

The present invention has been made in view of the above circumstances, and can realize stable automatic switching of cooling / heating mode without frequent repeated switching of cooling / heating and frequent switching of cooling / heating mode. An object of the present invention is to provide an automatic cooling / heating mode switching device for an air conditioner, which can prevent a failure of the air conditioner due to such a situation.

[0014]

The present invention has taken the following means in order to achieve the above object. The present invention corresponding to claim 1 is a cooling / heating mode automatic switching device for automatically switching between a cooling mode for cooling an air conditioner and a heating mode for heating the air conditioner. The underground temperature measuring means for measuring the temperature and the operation mode changing means for switching the cooling / heating mode of the air conditioner based on the underground temperature measured by the underground temperature measuring means are provided.

According to a second aspect of the present invention, there is provided a cooling / heating mode automatic switching device for automatically switching between a cooling mode for cooling an air conditioner and a heating mode for heating.
The underground temperature measuring means for measuring the underground temperature of the space whose temperature is controlled by the air conditioner is compared with the underground temperature measured by this underground temperature measuring means and the annual average temperature of the underground obtained in advance. When the measured underground temperature exceeds the annual average temperature, a cooling mode signal is generated, and when the measured underground temperature falls below the annual average temperature, a heating mode signal is generated. .

According to a third aspect of the present invention, there is provided a cooling / heating mode automatic switching device for automatically switching between a cooling mode for cooling an air conditioner and a heating mode for heating.
Underground temperature measuring means for measuring the underground temperature of the space whose temperature is controlled by the air conditioner at a plurality of different depths, and the underground temperature of a plurality of different depths obtained by this underground temperature measuring means The temperature distribution detecting means for obtaining the temperature distribution in the depth direction and the mode determining means for switching the cooling / heating mode of the air conditioner according to the state of the temperature distribution obtained by the temperature distribution detecting means.

[0017]

The present invention has the following effects by taking the above measures. According to the present invention corresponding to claim 1, for example, the underground temperature of the temperature control space such as a greenhouse is measured, and the heating mode or the cooling mode is switched based on the underground temperature. Since the cooling / heating mode is automatically switched in this way, it is possible to prevent forgetting the switching and erroneous switching that occur when the mode is switched manually.
In addition, since the cooling / heating mode can be switched based on the underground temperature that changes slowly throughout the year, there is no effect of temperature changes due to residual heat immediately after operation stop, which was a problem when switching operating modes based on temperature. Therefore, it is possible to prevent frequent operation mode switching.

According to the present invention corresponding to claim 2, when the underground temperature is above the annual average value, the cooling is carried out automatically when the underground temperature is above the annual average value, and when it is below the annual average value, the heating mode is automatically set. Can be switched.

According to the present invention corresponding to claim 3, the underground temperature of the space whose temperature is controlled by the air conditioner is measured at different depths and input to the temperature distribution detecting means. The temperature distribution detecting means obtains the temperature distribution in the depth direction from the underground temperatures at different depth positions. The slope of the temperature distribution obtained by the temperature distribution detecting means changes depending on the season. The mode determination means switches the cooling / heating mode of the air conditioner according to the state of this temperature distribution.

[0020]

Embodiments of the present invention will be described below. 1st Example of this invention is an example of the cooling / heating mode automatic switching apparatus of the air conditioner used for cooling / heating of a greenhouse.

FIG. 1 is a block diagram of a cooling / heating mode automatic switching apparatus according to the first embodiment. In the cooling / heating mode automatic switching device of the present embodiment, the cooling condition unit 13 controls the operation / stop of the cooling operation unit 11 performing the cooling operation in this air conditioner, and the operation / stop of the heating operation unit 12 performing the heating operation. Heating condition section 1
4 is in control. The cooling condition unit 13 sets the set value S in order to perform the cooling operation with hysteresis as shown in FIG. 7.
V, the cooling set value Sa, which is the start temperature of the cooling operation in which a large amount of hysteresis is added to the set value SV, and the cooling set value S
Sa ', which is the cooling temperature stop temperature obtained by subtracting a small amount of hysteresis from a, is preset. Heating condition section 14
In order to carry out the heating operation with hysteresis as shown in FIG. 7, the set value SV Sb ', which is the temperature at which the heating operation is stopped, with a small amount of hysteresis being set in advance. The cooling condition unit 13 and the heating condition unit 14 receive a measured temperature signal from a temperature sensor 15 installed in a greenhouse. Further, the cooling condition unit 13 and the heating condition unit 14 are switched by a mode switching signal provided from the operation mode changing unit 16.

The operation mode changing unit 16 switches the cooling / heating mode based on the underground temperature (Ts) input from the underground temperature sensor 17 installed underground in the greenhouse. Specifically, a set value (SV ') for the underground temperature and an operation temperature difference (Ta) are set in advance, and if Expression (1) is satisfied, a cooling mode signal for instructing a cooling operation is generated. , (2)
If the formula is satisfied, a heating mode signal for instructing heating operation is generated.

Ta>SV'-Ts (1) Ta≤SV'-Ts (2) The set value SV 'is a set value of the underground temperature determined corresponding to the cooling set value of the cooling condition section. Yes, the difference from the predicted maximum temperature Tmax in the ground is set to be smaller than Ta.

Next, the operation of the present embodiment configured as described above will be described. Generally, the underground temperature is maximum around July and August, and is lowest around January and February. And
The change in the underground temperature throughout the year shows a gentle sine curve as shown in FIG.

The operation mode changing unit 16 detects the difference between the underground temperature Ts showing such a stable change and the set value SV 'at regular intervals. When the difference between the two becomes smaller than the operation temperature difference (Ta) determined separately, the cooling mode is selected. If the difference between the two becomes larger than the operation temperature difference (Ta) determined separately, the heating mode is selected. Here, since the cooling mode signal / heating mode signal output from the operation mode changing unit 16 is switched according to the underground temperature Ts where the temperature changing speed is slow, the problem that the cooling / heating mode is frequently switched is prevented.

When the cooling mode signal is output from the operation mode changing unit 16, the cooling condition unit 13 operates and the heating condition unit 14 enters a standby state. When the heating mode signal is output, the heating condition unit 14 operates and the cooling condition unit 13 enters the standby state.

For example, it is assumed that the cooling operation by the cooling operation unit 11 which has received the cooling operation signal from the cooling condition unit 13 reduces the temperature in the greenhouse to Sa 'and the cooling operation is stopped. Even if the temperature inside the greenhouse reaches the heating set value Sb as a result of the temperature inside the greenhouse decreasing due to the cold heat of the air conditioner even after the cooling operation is stopped, the underground temperature inside the greenhouse is not directly affected by the cold heat, so it is short. It does not decrease in time. Therefore, in the operation mode changing unit 16, the condition of the expression (1) remains satisfied, so that the cooling mode signal remains output and the heating mode signal for operating the heating condition unit 14 is not generated.

Further, it is assumed that the heating operation by the heating operation unit 12 which receives the heating operation signal from the heating condition unit 14 raises the temperature in the greenhouse to the temperature Sb 'and the heating operation is stopped. Even after the heating operation is stopped, even if the temperature in the greenhouse reaches the cooling set value Sa as a result of the temperature in the greenhouse rising due to the heat of the air conditioner, the underground temperature in the greenhouse is not directly affected by the heat, and therefore the temperature is short. It does not rise in time. Therefore, in the operation mode changing unit 16, the condition of the expression (2) remains satisfied, so that the heating mode signal remains output, and the cooling mode signal for operating the cooling condition unit 13 is not generated.

As described above, according to this embodiment, the underground temperature T
The operating temperature difference T in which the temperature difference between s and the set value SV 'is determined separately.
As compared with a, the switching signal of the cooling / heating mode is generated and given to the cooling condition unit 13 and the heating condition unit 14 depending on its magnitude, so it is possible to prevent frequent switching between the cooling mode and the heating mode. .

Next, a second embodiment of the present invention will be described. FIG. 2 is a configuration diagram of the cooling / heating mode automatic switching device according to the second embodiment. The parts having the same functions as those in the first embodiment described above are designated by the same reference numerals to avoid duplication of description.

In this embodiment, the normal temperature value of the ground temperature (annual ground temperature average value AVT) is preset in the operation mode changing unit 16 'from the ground temperature setting unit 18, and the ground temperature sensor 17 drives the ground. The medium temperature signal is being input.

The operation mode changing unit 16 'has a normal value (AV
T) is compared with the underground temperature Ts to generate a warm / warm mode switching signal, which is input to the cooling condition unit 13 and the heating condition unit 14. In the present embodiment configured as described above, the operation mode changing unit 16 'takes in the underground temperature signal from the underground temperature sensor 17 and performs a comparison process between the normal value (AVT) and the underground temperature Ts. Based on the comparison result, as shown in FIG. 4, if the underground temperature Ts is below the normal value (AVT), a heating mode signal is generated, and conversely, the underground temperature Ts is below the normal value (AV).
If T) is exceeded, a cooling mode signal is generated.

In the cooling condition section 13 and the heating condition section 14,
The same operation as in the first embodiment described above is performed by the heating / cooling mode switching signals such as the heating mode signal and the cooling mode signal provided from the operation mode changing unit 16 '.

In this embodiment as well, the cooling / heating mode is switched based on the underground temperature.
The same effects as those of the first embodiment can be obtained. Next, a third embodiment of the present invention will be described.

FIG. 3 is a block diagram of the cooling / heating mode automatic switching device according to the third embodiment. The parts having the same functions as those in the first embodiment described above are designated by the same reference numerals to avoid duplication of description. In this embodiment, in order to measure the distribution of the underground temperature of the greenhouse in the depth direction, a plurality of underground temperature sensors 17-1 are used.
.About.17-n are installed at different depth positions in the ground. The signals output from these underground temperature sensors 17-1 to 17-n are input to the operation mode changing unit 20.

The operation mode changing unit 20 is shown in FIG. 5 based on the signals input from the temperature sensors 17-1 to 17-n in each place.
A temperature distribution detecting unit 21 for detecting a temperature distribution curve of the underground temperature in the depth direction as shown in FIG. 6 and a cooling / heating mode switching signal is generated according to the slope of the temperature distribution curve detected by the temperature distribution detecting unit 21. It has a cooling / heating mode determination unit 22.

FIG. 5 shows a general underground temperature distribution.
The temperature distribution in the ground is constant at 15 degrees throughout the year in 1 m of the ground, and changes as it approaches the surface of the earth. (A) in the figure
Shows the temperature distribution in summer, (b) shows the temperature distribution in winter, (c) shows the temperature distribution in spring, and (d) shows the temperature distribution in autumn. As shown in these temperature distributions (a) to (c), when the slope of the temperature distribution from the ground surface to the underground is large on the right side, the temperature is high, and when it is large on the left side, the temperature is low.

Next, the operation of the present embodiment configured as above will be described. In this embodiment, the temperature distribution detecting unit 21 of the operation mode changing unit 20 has a temperature sensor 17-
Signals are input from 1 to 17-n. Temperature distribution detector 21
Is the signal from the temperature sensors 17-1 to 17-n,
A temperature distribution curve is created by plotting depth on the vertical axis and temperature on the horizontal axis. The cooling / heating mode determination unit 22 detects the slope of the temperature distribution curve created in this way, and switches the cooling / heating mode according to the slope. For example, if the slope of the temperature distribution curve is close to (a) and (c) of FIG. 5, a cooling mode signal is generated, and if the slope of the temperature distribution curve is close to (b) and (d) of FIG. Generate a signal.

In the cooling condition unit 13 and the heating condition unit 14 which have received the cooling / heating mode switching signal thus generated,
The cooling operation or the heating operation is performed by operating in the same manner as in the first embodiment described above.

As described above, according to this embodiment, the temperature distribution curve in the ground is obtained, and the cooling / heating mode is switched based on the inclination thereof, so that the cooling mode and the heating mode are prevented from frequently switching. be able to. The present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

[0041]

As described in detail above, according to the present invention, stable automatic switching of the cooling / heating mode can be realized without frequent and frequent switching of the cooling / heating, and the air conditioning by the frequent switching of the cooling / heating mode. It is possible to provide a cooling / heating mode automatic switching device for an air conditioner capable of preventing a failure of the device.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a cooling / heating mode automatic switching device according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram of a cooling / heating mode automatic switching device according to a second embodiment of the present invention.

FIG. 3 is a functional block diagram of a cooling / heating mode automatic switching device according to a third embodiment of the present invention.

FIG. 4 is a model diagram of a secular change in underground temperature.

FIG. 5 is a temperature distribution diagram of the underground temperature in the depth direction.

FIG. 6 is a configuration diagram of a conventional manual heating / cooling mode switching device.

FIG. 7 is a diagram showing an operation example in which the operation of the air conditioner has hysteresis.

[Explanation of symbols]

11 ... Cooling operation part, 12 ... Heating operation part, 13 ... Cooling condition part, 14 ... Heating condition part, 15 ... Temperature sensor, 16 ... Operation mode changing part, 17 ... Underground temperature sensor, 18 ... Underground temperature setting device , 21 ... Temperature distribution detection unit, 22 ... Cooling / heating mode determination unit.

Claims (3)

[Claims] 1. An automatic cooling / heating mode switching device for automatically switching between a cooling mode for cooling an air conditioner and a heating mode for heating the air conditioner, wherein a ground temperature of a space whose temperature is controlled by the air conditioner is measured. An automatic cooling / heating mode switching device for an air conditioner, comprising: an intermediate temperature measuring means; and an operation mode changing means for switching the cooling / heating mode of the air conditioner based on the underground temperature measured by the underground temperature measuring means. . 2. An automatic cooling / heating mode switching device for automatically switching between a cooling mode for cooling the air conditioner and a heating mode for heating the air conditioner, wherein a ground temperature of a space whose temperature is controlled by the air conditioner is measured. Generates an air-conditioning mode signal when the underground temperature measured by comparing the underground temperature measured by this underground temperature measuring means and the previously determined annual average temperature of the underground exceeds the annual average temperature. And an operation mode changing means for generating a heating mode signal when the measured underground temperature falls below the annual average temperature. 3. A cooling / heating mode automatic switching device for automatically switching between a cooling mode for cooling an air conditioner and a heating mode for heating an air conditioner, wherein the underground temperature of a space whose temperature is controlled by the air conditioner is controlled to a depth. Underground temperature measuring means for measuring at a plurality of different points, temperature distribution detecting means for obtaining a temperature distribution in the depth direction from underground temperatures at a plurality of points having different depths obtained by the underground temperature measuring means, and this temperature distribution An automatic cooling / heating mode switching device for an air conditioner, comprising: a mode determining unit for switching the cooling / heating mode of the air conditioner in accordance with the temperature distribution state obtained by the detection unit.