JPH0533988A - Operation controller for air conditioner - Google Patents

Abstract

PURPOSE:To reduce a freezing preventing operation by decreasing a frosting region of an indoor heat exchanger. CONSTITUTION:The operation controller for an air conditioner comprises a refrigerant circuit 11 in which a compressor 21, an outdoor heat exchanger 22 having an air flow rate variable outdoor fan 23 attached to H-tap and L-tap air flow rate stages, and a motor-driven expansion valve 31 are sequentially connected. Further, the controller comprises an atmospheric air temperature sensor Th1 and a room temperature sensor Th4. In addition, the controller comprises air flow rate control means 51 for switching the fan 23 to an H-tap to increase an air flow rate when a detected atmospheric air temperature detected by the sensor Th1 becomes higher than a set atmospheric air temperature obtained from a room temperature detected by the sensor Th4 based on a set atmospheric air temperature characteristic so preset as to rise the room temperature as the room temperature falls whereas switching the fan 23 to an L-tap to decrease the air flow rate when the detected atmospheric air temperature becomes lower than the set atmospheric air temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for an air conditioner, and more particularly to a measure for controlling the air flow rate of an outdoor fan.

[0002]

2. Description of the Related Art In general, some air conditioners are constructed so that an outdoor fan can switch between an H tap with a high air volume and an L tap with a low air volume. And Japanese Patent Application No. 2-405705
As disclosed in No. 6, when the outside air temperature is high at the time of starting the compressor, the outdoor fan is set to H tap to increase the air volume, while when the outside air temperature is low, the outdoor fan is set to L tap. There are some that try to reduce the air volume.

That is, as shown in FIG. 6, when the outside air temperature is lower than a high temperature and is lower than 17 ° C., the outdoor fan is turned on.
Switch to tap, on the other hand, outside temperature rises from a low state,
When the temperature rises above 20 ° C, the outdoor fan is switched to the H tap.

[0004]

In the above-mentioned air conditioner, the cooling operation may be performed throughout the year, that is, the cooling operation may be performed even in a low outside air temperature state.

In this case, when the outdoor fan is operated with an L tap, there is a region A where frost is formed on the indoor heat exchanger when the indoor temperature is low and the outdoor air temperature is low, and the outdoor fan is operated. When operating with the H tap, there was a region B where frost was formed on the indoor heat exchanger even when the indoor temperature was low and the outside air temperature was slightly low.

That is, conventionally, since the outdoor fan is switched between the H tap and the L tap only at a constant outside air temperature, when the outdoor fan is operated by the H tap, the outside air temperature and the indoor temperature are When both are low, there is a problem that the condensation pressure is reduced and the evaporation pressure is reduced to cause frost formation on the indoor heat exchanger, and the antifreezing operation must be performed.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the frosting region of the indoor heat exchanger and reduce the antifreezing operation.

[0008]

In order to achieve the above object, the means taken by the present invention is to change the set outside air temperature for switching the outdoor fan according to the indoor temperature.

Specifically, as shown in FIG. 1, in the means taken by the invention according to claim 1, first, a compressor (21) and an outdoor fan (23) with a variable air volume for a plurality of air volume stages are attached. It is premised on an air conditioner including a refrigerant circuit (11) in which the outdoor heat exchanger (22), the expansion mechanism (31), and the indoor heat exchanger (32) are connected in order.

Further, an outside air temperature detecting means (Th1) for detecting the outside air temperature and an indoor temperature detecting means (Th4) for detecting the indoor temperature are provided. In addition, from the set outdoor air temperature obtained from the indoor temperature detected by the indoor temperature detecting means (Th4) based on the preset outdoor air temperature characteristic set in advance so that the indoor temperature rises as the indoor temperature becomes lower than the indoor temperature. Also, when the detected outside air temperature detected by the outside air temperature detecting means (Th1) becomes high, the number of air flow stages of the outdoor fan (23) is switched to increase the air flow, while when the detected outside air temperature becomes lower than the set outside air temperature, An air volume control means (51) for reducing the air volume by switching the number of air volume stages of the outdoor fan (23) is provided.

Further, in the invention according to claim 2, in the invention according to claim 1, the set outside air temperature characteristic is set so as to increase at a rate of change substantially equal to the rate of decrease of the indoor temperature.

[0012]

With the above construction, in the invention according to claim 1,
First, the high-pressure refrigerant compressed in the compressor (21) is condensed in the outdoor heat exchanger (22), decompressed by the expansion mechanism (31), evaporated in the indoor heat exchanger (32), and then the compressor ( Two
Returning to 1), the room is cooled by the indoor heat exchanger (32).

During this cooling operation, the outdoor fan (2
3) is an air volume control means (5) based on the set outside air temperature characteristic.
1) is switching the number of airflow stages. The set outside air temperature characteristic rises as the indoor temperature becomes lower. Specifically, in the invention according to claim 2, the set outside air temperature characteristic rises at a rate of change substantially equal to the rate of decrease of the indoor temperature, and the indoor temperature calculated from the set outside air temperature characteristic When the outside air temperature detected by the outside air temperature detection means (Th1) becomes lower than the set outside air temperature corresponding to the temperature, the number of air flow stages of the outdoor fan (23) is switched to reduce the air flow, while the detected outside air temperature is higher than the set outside air temperature. Then, the number of airflow stages of the outdoor fan (23) is switched to increase the airflow. As a result, even in the low outside air temperature, the indoor heat exchanger (32) continues to be cooled without frosting.

[0014]

Therefore, according to the first and second aspects of the present invention, the set outside air temperature for switching the outdoor fan (23) is changed according to the indoor temperature.
When the outdoor temperature is low and the indoor temperature is low, the outdoor fan (2
Since 3) is operated at a low air volume instead of being operated at a high air volume, the condensation pressure can be increased and the evaporation pressure can be increased, so that the indoor heat exchanger (32) is frosted. Can be prevented. As a result, the number of freeze prevention operations can be reduced, and thus the continuous cooling operation can be performed.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

As shown in FIG. 2, (1) is an air conditioner, which is a cooling-only machine, and is constituted by an outdoor unit (2) and an indoor unit (3).

Further, a compressor (21) and an outdoor heat exchanger (22) mounted on the outdoor unit (2), an electric expansion valve (31) which is an expansion mechanism mounted on the indoor unit (3), and The indoor heat exchanger (32) is sequentially connected by a refrigerant pipe to form a refrigerant circuit (11).
The outdoor heat exchanger (22) has an outdoor fan (2
3) has an indoor fan (33) in the indoor heat exchanger (32)
, And the outdoor fan (23) is configured such that the number of airflow stages can be switched between a high airflow H tap and a low airflow L tap. And the compressor (21)
The high-pressure refrigerant that has been compressed in 1. is condensed in the outdoor heat exchanger (22), decompressed by the electric expansion valve (31), then evaporated in the indoor heat exchanger (32) and returned to the compressor (21). Incidentally, the indoor heat exchanger (32) exchanges heat with the indoor air to cool the room.

Further, the outdoor unit (2) is provided with an outside air temperature sensor (Th1) which is an outside air temperature detecting means arranged on the air intake side to detect the outside air temperature.
An outdoor liquid pipe sensor (Th2) arranged in the liquid pipe of the outdoor heat exchanger (22) for detecting the condensation temperature is provided, while a discharge arranged in the discharge pipe of the compressor (21) for detecting the discharge pipe temperature. A tube sensor (Th3) is provided. Further, the indoor unit (3) is provided with a room temperature sensor (T which is an indoor temperature detecting means arranged on the air intake side to detect an indoor temperature.
h4) is provided and is arranged in a liquid pipe of the indoor heat exchanger (32) to detect an evaporation temperature, an indoor liquid pipe sensor (Th
5) is provided.

Then, each of the above sensors (Th1) to (Th5)
Is connected to a controller (5), and the controller (5) is configured to perform cooling operation control. For example, while controlling the thermo-on / off operation so that the room temperature becomes a set room temperature, An optimum discharge pipe temperature is calculated from the condensation temperature and the evaporation temperature, and the opening of the electric expansion valve (31) is controlled so that the discharge pipe temperature is within a predetermined range with respect to the optimum discharge pipe temperature. Has been done.

Further, the controller (5) is provided with an air volume control means (51) for controlling the air volume of the outdoor fan (23) as a feature of the present invention. The air volume control means (51) is obtained from the room temperature detected by the room temperature sensor (Th4) based on a preset outside air temperature characteristic that is set so as to rise as the room temperature becomes lower than the room temperature. When the detected outside air temperature detected by the outside air temperature sensor (Th1) becomes higher than the set outside air temperature, the number of airflow stages of the outdoor fan (23) is switched to H taps to increase the airflow, while the detected outside air temperature is set to the above set outside air temperature. When the temperature becomes lower than the temperature, the number of airflow stages of the outdoor fan (23) is switched to L taps to reduce the airflow.

Specifically, the set outside air temperature characteristic is shown in FIG.
As shown in Fig. 4, the first set outside air temperature Ts1 and the second set outside air temperature Ts2, which rise at a rate of change equal to the rate of decrease of the indoor temperature Tr, are included. The first set outside air temperature Ts1 and the second set outside air temperature Ts2. And are set as shown in the following equation.

Ts1 = 44−Tr (1) Ts2 = 47−Tr (2) Then, the air volume control means (51) detects the detected outside air temperature Ta.
When the outdoor fan (23) is switched from the H tap to the L tap when the temperature falls below the first set outside air temperature Ts1, the detected outside air temperature Ta rises and the second set outside air temperature Ts rises.
When it becomes higher than 2, the outdoor fan (23) is changed from L tap to H
I am trying to switch to taps.

Here, the first set outside air temperature Ts1 and the second
The basic reason for changing the set outside air temperature Ts2 in accordance with the indoor temperature Tr will be described with reference to FIG. In FIG. 5, the indoor load is constant.

As shown in FIG. 5 (a), the high pressure, which is the condensing pressure, increases as the outside air temperature Ta rises in both the H tap and the L tap of the outdoor fan (23). On the other hand, as shown in FIG. 5 (b), the flow rate characteristic of the compressor (21) decreases as the outside air temperature Ta increases in both the H tap and the L tap of the outdoor fan (23).

Further, as shown in FIG. 5 (c), regarding the flow characteristic of the electric expansion valve (31), if the flow characteristic of the compressor (21) is constant, the outdoor fan (23) is H tap and L. In any of the taps, the set flow rate (100%) flows in the control region S, and decreases in the fully open state P as the outside air temperature Ta decreases. Conversely, at the minimum opening C, the outside air temperature Ta decreases.
It will increase as Ta increases.

As a result, as shown in FIG. 5 (d), the flow rate characteristics of the entire system of the refrigerant circuit (11) ensure a proper refrigerant circulation amount in the control region S of the electric expansion valve (31). On the other hand, in the fully open state P of the electric expansion valve (31), since no differential pressure is generated, the refrigerant circulation amount decreases as the outside air temperature Ta decreases, and at the minimum opening C, the compressor (2
From the flow rate characteristic of 1), the amount of refrigerant supplied from the compressor (21) decreases, and the refrigerant circulation amount decreases as the outside air temperature Ta increases.

In this state, as shown in FIG. 5 (e), the low pressure, which is the evaporation pressure, maintains a constant pressure in the control region S of the electric expansion valve (31) because a proper refrigerant circulation amount is secured. On the other hand, in the fully open state P of the electric expansion valve (31), since the compressor (21) itself has a suction force, the refrigerant circulation amount decreases and the low pressure decreases as the outside air temperature Ta decreases. . On the contrary, the electric expansion valve (3
At the minimum opening degree C of 1), the amount of refrigerant supplied from the compressor (21), that is, the suction force decreases and the amount of refrigerant circulation increases as the outside air temperature Ta increases from the flow rate characteristics of the compressor (21). Although it decreases, the low pressure will increase.

Therefore, in the region X where the low pressure is reduced by the H tap of the outdoor fan (23), the outdoor fan (23) is set to L.
I try to tap it.

Next, air volume control of the outdoor fan (23) will be described based on the control flow shown in FIG.

First, when the cooling operation is started by a remote controller or the like, the start control is performed in step ST.
The outdoor fan (23) is set to H tap.

Then, in step ST2, the outside air temperature Ta is taken in from the outside air temperature sensor (Th1) and the indoor temperature Tr is taken in from the room temperature sensor (Th4). Then, step ST
3, the outside air temperature Ta detected by the outside air temperature sensor (Th1)
Is higher than the second set outside air temperature Ts2. If the detected outside air temperature Ta is higher than the second set outside air temperature Ts2, the process proceeds to step ST4 and the outdoor fan (2
3) is left at the H tap and the process proceeds to step ST5, and the normal cooling operation control of the outdoor fan (23) and the like is performed.

On the other hand, in step ST3, if the detected outside air temperature Ta is lower than the second set outside air temperature Ts2, the determination is NO, the process proceeds to step ST6, and the detected outside air temperature is
It is determined whether Ta is lower than the first set outside air temperature Ts1. The detected outside air temperature Ta is the first set outside air temperature Ts1.
Until it further decreases, the routine proceeds to step ST5, and the normal control is performed, while if the detected outside air temperature Ta falls below the first set outside air temperature Ts1 in step ST6, the determination becomes YES and the outdoor fan (23 ) Switch the number of air flow stages to L taps, reduce the air flow and perform the above step ST
Then, the procedure goes to step 5 to continue the normal control.

That is, when the detected outside air temperature Ta decreases from a high state, the outdoor fan (23) is switched from the H tap to the L tap with the first set outside air temperature Ts1 as a reference. When the temperature Ta rises from a low state, the outdoor fan (23) is switched from the L tap to the H tap based on the second set outside air temperature Ts2.

Since the second set outside air temperature Ts2 and the first set outside air temperature Ts1 change depending on the room temperature Tr, for example, when the room temperature Tr is 27 ° C. (dry valve), the detected outside air temperature is When Ta decreases from a high temperature, the outdoor fan (23) is switched from H tap to L tap at the first set outside air temperature Ts1 of 17 ° C.
On the other hand, when the detected outside air temperature Ta rises from a low temperature, the outdoor fan (23) is switched from the L tap to the H tap at the second set outside air temperature Ts2 of 20 ° C. As a result, conventionally, the low outside air temperature Ta and the low indoor temperature Tr
In the region B in which the outdoor fan (23) is H tapped in this state, in the present embodiment, the outdoor fan (23) is switched to the L tap to reduce the air volume.

Therefore, since the set outdoor air temperature Ta for switching the outdoor fan (23) is changed according to the indoor temperature Tr, conventionally, the outdoor fan (23) is set to H at the low outdoor air temperature Ta and the indoor temperature Tr. Instead of operating with a high air volume of the tap, it operates with a low air volume of the L tap, and it is possible to raise the high pressure, which is the condensation pressure, and the low pressure, which is the evaporation pressure. Exchanger (3
2) Frost formation can be prevented. As a result, the number of freeze prevention operations can be reduced, and thus the continuous cooling operation can be performed.

In this embodiment, the air conditioner (1) dedicated to cooling is explained, but the present invention may be applied to various air conditioners such as a heat pump type capable of cooling and heating operation.

Further, the number of airflow stages of the outdoor fan (23) is not limited to two stages, and may be switched to a plurality of stages such as three stages or four stages.

Also, the first set outside air temperature Ts1 and the second
The set outside air temperature Ts2 may be a rate of change substantially equal to the rate of change of the indoor temperature Tr.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a refrigerant circuit diagram showing an air conditioner of the present invention.

FIG. 3 is a diagram showing a control region of an outside air temperature and an indoor temperature in the present invention.

FIG. 4 is a control flow chart of the outdoor fan in the present invention.

[Fig. 5] (a), (b), (c), (d), and (e) are high-pressure characteristics with respect to outside air temperature, compressor flow characteristics, electric expansion valve flow characteristics, and system refrigerant circulation amount characteristics, respectively. It is a figure which shows and a low voltage characteristic.

FIG. 6 is a diagram showing a conventional control region of outside air temperature and indoor temperature.

[Explanation of symbols] 21 compressor 22 Outdoor heat exchanger 23 Outdoor fan 31 Electric expansion valve (expansion mechanism) 32 Indoor heat exchanger 51 Air flow control means Th1 outside air temperature sensor (outside air temperature detection means) Th4 room temperature sensor (room temperature detection means)

Claims (2)

[Claims] 1. A compressor (21), an outdoor heat exchanger (22) provided with an outdoor fan (23) having a variable air volume for a plurality of air volume stages, an expansion mechanism (31), and an indoor heat exchanger ( Three
In an air conditioner provided with a refrigerant circuit (11) in which 2) are connected in order, an outside air temperature detecting means (Th1) for detecting an outside air temperature, an indoor temperature detecting means (Th4) for detecting an indoor temperature, The outside air temperature is higher than the set outside air temperature obtained from the indoor temperature detected by the indoor temperature detection means (Th4) based on the set outside air temperature characteristic set in advance so that the indoor temperature rises as the indoor temperature decreases. Temperature detection means (T
When the detected outside air temperature detected by h1) becomes high, the number of airflow stages of the outdoor fan (23) is switched to increase the airflow, while when the detected outside air temperature becomes lower than the set outside air temperature,
An operation control device for an air conditioner, comprising: an air volume control means (51) for reducing the air volume by switching the number of air volume stages of the outdoor fan (23). 2. The air conditioner operation control apparatus according to claim 1, wherein the set outside air temperature characteristic is set so as to increase at a rate of change substantially equal to a rate of decrease of the indoor temperature. Operation control device for the harmony device.