JPH09210427A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioner, capable of maintaining a cooling capacity and a dehumidifying capacity as much as possible upon controlling the preventing of freezing. SOLUTION: When the number of rotation of a compressor is limited so as to be lower than a predetermined value in accordance with the temperature TE of an indoor heat exchanger upon the operation mode of cooling or drying, a set temperature (α) for preventing condensation is changes in reference to the ventilating amount of an indoor fan. In this case, when the ventilating amount of the indoor fan (or the number of rotation Fn) is larger, the set temperature (α) for preventing condensation is set lower. For example, the objective number of rotation of the compressor is set based on a difference between the detecting value and the set value of an indoor temperature and when the temperature of the indoor heat exchanger has become at most the set temperature for preventing condensation, which is set employing the amount of ventilation as a parameter, the objective number of rotation is limited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for performing freeze prevention control on an indoor heat exchanger in a cooling or dry operation mode.

[0002]

2. Description of the Related Art When an air conditioner is operated in a cooling mode or a dry mode, dew adheres to an indoor heat exchanger, and when the amount increases, the dew drops and is discharged as drain water. However, when the temperature of the indoor heat exchanger becomes 0 ° C. or lower, the dew attached to the indoor heat exchanger may be frozen. Therefore, conventionally, a temperature sensor is attached to the indoor heat exchanger, and when the detected value becomes equal to or lower than the set temperature for preventing dew condensation higher than 0 ° C., the number of revolutions of the compressor is limited to a predetermined value or less, and the indoor temperature is still reduced. When the temperature of the heat exchanger drops below the set temperature for freeze prevention around 0 ° C., control is performed to sequentially decrease the rotation speed of the compressor by a predetermined value at predetermined time intervals.

FIGS. 5 (a) and 5 (b) are explanatory views for explaining the contents of this control. This control is basically performed by the compressor so that the frost adhering to the indoor heat exchanger does not freeze. The number of revolutions, in other words, the frequency of the electric power supplied to the compressor drive motor (hereinafter abbreviated as compressor frequency) is kept low,
This is a control for reducing the air conditioning capacity.

[0004] In this case, (a), the descends the temperature T _E of the indoor heat exchanger, the prevention dew set temperature T _C2
In the following cases, as shown in (b), the control for limiting the maximum value of the compressor frequency Hz, which is determined by using the blow rate or the rotational speed F _n of the indoor fan at that time, that is, the dew prevention control is performed. Run. Even if the dew condensation prevention control is executed, if the temperature T _E of the indoor heat exchanger continues to drop and becomes equal to or lower than the set temperature T _{C4 for} freezing prevention, the compressor frequency Hz is kept constant at regular intervals. Executes anti-freezing control to reduce the value. On the other hand, when the temperature T _E of the indoor heat exchanger rises due to the execution of the antifreezing control and the temperature exceeds the antifreezing set temperature T _C3 , the dew condensation preventing control is performed,
Further, when the temperature T _E of the indoor heat exchanger rises and exceeds the set temperature T _C1 for preventing dew condensation, the dew condensation prevention control is released and the normal operation is started.

The set temperature for preventing dew condensation is made to have a temperature difference β between T _C2 at the time of lowering and T _C1 at the time of rising, and the set temperature for preventing freezing is set to T _C4 at the time of lowering.
The reason why there is a difference between T _C3 at the time of rising and T _C3 at the time of rising is to prevent hunting of the compressor frequency Hz in that temperature range. Originally, the temperature T _C3 at the time of temperature rise should be called a set temperature for canceling the freeze prevention control, and T _C1 should be called a set temperature for canceling the dew condensation prevention control. In this specification, the temperature T _C3 is called. Is also referred to as a freezing prevention set temperature, and the temperature T _C1 is also referred to as a dew condensation prevention set temperature. And
Set temperature T _C2, T normal operation zone area beyond the _C1 antifreeze, prevention control zone with a region surrounded by the set temperature T _C4, T _C3 of antifreeze and the set temperature T _C2, T _C1 of preventing dew dew , A region lower than the set temperatures T _C4 and T _{C3 for} freeze prevention is called a freeze release zone.

[0006]

The antifreezing control described above includes the possibility of finally stopping the compressor and interrupting the cooling or dry operation. Therefore, it can be said that the dew condensation prevention control is a control for making it difficult to enter the freeze prevention control by limiting the compressor frequency Hz. by the way,
The rotation speed of the indoor fan is, as shown in FIG.
Corresponding to "quiet wind""lightwind""weakwind""strongwind" 4
Many of them try to switch to one stage. In general, when the amount of air blown is “quiet” or “light”, the temperature of the indoor heat exchanger drops, and dew adheres easily to freeze.
On the other hand, it is known that dew adherence and freezing to the indoor heat exchanger are unlikely to occur in the case of "strong wind" in which a large amount of air is blown.

However, in the above-described conventional dew condensation prevention control, the set temperatures T _C2 and T _{C1 for} dew condensation prevention are uniformly determined irrespective of the amount of air blown by the indoor fan, and moreover, the dew condensation on the indoor heat exchanger is prevented. It was decided on the basis of a small amount of air that easily adheres and freezes. For this reason, even though the dew condensation prevention control at the time of a large air volume is too early and there is no possibility of entering the frozen release zone, the dew condensation prevention control is performed, so the cooling or dehumidifying capacity of the air conditioner is low. It was sometimes suppressed.

The present invention has been made to solve the above problems, and provides an air conditioner capable of maintaining a cooling capacity or a dehumidifying capacity as large as possible in controlling antifreezing. To aim.

[0009]

In the air conditioner according to the present invention, when the number of revolutions of the compressor is limited to a predetermined value or less in accordance with the temperature of the indoor heat exchanger in the cooling or dry operation mode, The set temperature for preventing dew condensation is changed in association with the amount of air blown from the indoor fan, whereby the cooling capacity or dehumidifying capacity can be maintained as large as possible.

In this case, the larger the amount of air blown by the indoor fan, the lower the set temperature for preventing dew condensation,
The room before dew adheres to the indoor heat exchanger and freezes,
The same degree can be achieved over the entire variation range of the fan rotation speed.

Further, the target rotational speed of the compressor is set on the basis of the difference between the detected value and the set value of the indoor temperature, and the temperature of the indoor heat exchanger is equal to or lower than the set temperature for preventing dew condensation, which is determined by the air flow rate as a parameter. Then, by limiting the target rotation speed, it is possible to easily and surely control.

Since it is difficult to detect the air flow rate strictly, the dew condensation prevention control by the set temperature for dew condensation prevention associated with the air volume is facilitated by referring to the rotation speed of the indoor fan instead. To be done.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings. FIG. 2 is a schematic configuration diagram of an embodiment of the present invention. In the figure, 1 is a compressor,
The refrigerant discharged from here passes through the outdoor heat exchanger 2, which functions as a condenser, the expansion valve 3, and the indoor heat exchanger 4, which functions as an evaporator, and is sucked into the compressor 1 as shown by arrow A. . Here, an outdoor fan 5 for promoting heat exchange of the outdoor heat exchanger 2 and an indoor fan 6 for promoting heat exchange of the indoor heat exchanger 4 are provided. The inverter device 10 converts alternating current obtained from an alternating current power source (not shown) into direct current, converts the alternating current into alternating current according to the target value of the compressor frequency Hz calculated by the control circuit 11, and supplies the alternating current to the electric motor driving the compressor 1. To do. A fan air volume setting device 12 for manually setting the air volume of the indoor fan 6 is connected to the control circuit 11, and the control circuit 11 controls the rotation speed F _n of the indoor fan 6 according to the set value of the air volume. It is like this. On the other hand, a temperature sensor 13 for detecting the indoor temperature T _A is provided,
Further, a temperature sensor 14 for detecting the temperature T _E of the indoor heat exchanger 4 is provided, and each detected value is a control circuit.
Taken in 11. Further, the set room temperature T _S set by a setting device (not shown) is taken into the control circuit 11.

The operation of the present embodiment configured as described above will be described below. First, the control circuit 11 determines the set room temperature T _S and the room temperature T _S detected by the temperature sensor 13.
_A target value of the compressor frequency Hz is calculated based on the difference from _A and given to the inverter device 10. The inverter device 10 supplies the AC power that follows the target value of the compressor frequency Hz to the compressor 1
Supply to the electric motor that drives the. As a result, the compressor 1
The gas refrigerant discharged from the heat exchanger 2 releases heat in the outdoor heat exchanger 2 to become a liquid refrigerant, and the liquid refrigerant sent to the indoor heat exchanger 4 through the expansion valve 3 absorbs heat there to become a gas refrigerant. The gas refrigerant is sucked into the compressor 1. Therefore, cooling or dry air conditioning control is performed with a capacity according to the air conditioning load. In addition, the calculation of the compressor frequency Hz,
Alternatively, since the control of the inverter device 10 is publicly known, detailed description thereof will be omitted. Also, the outdoor fan 5
The control of the number of revolutions is also not directly related to the present invention, and therefore its description is omitted.

Next, the control circuit 11 controls the number of revolutions F _n of the indoor fan 6 so that the air volume manually set by the fan air volume setting device 12 can be obtained. That is, the amount of air blown into the room through the indoor heat exchanger 4 is controlled to the set value. At this time, the temperature sensor 14 controls the temperature T of the indoor heat exchanger 4.
_E is detected and added to the control circuit 11. The control circuit 11 executes the dew condensation prevention control and the freeze prevention control according to the detected indoor heat exchanger temperature T _E.

FIGS. 1A and 1B are explanatory views for explaining the control contents. In the figure, when the temperature T _E of the indoor heat exchanger drops and becomes equal to or lower than the set temperature α for preventing dew condensation as shown in (a), as described above, the rotation speed F of the indoor fan at that time point. _The dew condensation prevention control that limits the maximum value of the compressor frequency Hz that is predetermined with _n as a parameter, that is, the control described with reference to FIG. Even if the dew condensation prevention control is executed, if the temperature T _E of the indoor heat exchanger continues to drop and becomes equal to or lower than the set temperature T _{C4 for} freezing prevention, the compressor frequency Hz is kept constant at regular intervals. Executes anti-freezing control to reduce the value. on the other hand,
By executing the antifreezing control, the temperature T _E of the indoor heat exchanger rises, and when it exceeds the set temperature T _C3 for antifreezing, the dew condensation preventing control is performed, and further, the indoor heat exchanger Temperature T _E rises and set temperature (α + β) to prevent dew condensation
When it exceeds, the dew condensation prevention control is released and the operation shifts to normal operation.

The difference between the conventional apparatus and the present embodiment lies in whether the set temperature for preventing dew condensation is fixed or variable. That is, in the conventional device shown in FIG. 5, the dew adheres and is fixed to T _C2 and T _C1 on the basis of the small air volume that is likely to freeze, whereas in the present embodiment, the indoor fan 6 is fixed. The configuration is such that α and (α + β) are changed and set according to the air volume. Of these, β is a constant value set to prevent hunting of the compressor frequency Hz in that temperature range as described above, and is changed following the change of α depending on the air volume.

FIG. 1 (b) shows the relationship between the set temperature α for preventing dew condensation set in the temperature fluctuation range of the indoor heat exchanger and the air volume associated with the rotational speed F _n of the indoor fan.
The set temperature α for preventing dew condensation is set according to a stepwise decreasing function when the rotation speed F _n of the indoor fan is used as a variable. In other words, in the "quiet wind" area where the air flow rate is the smallest, the temperature value is α ₁ which is the highest, and in the "light air flow" area where the air flow rate is higher than that, it is α ₂ (<α ₁ ). It is set to α ₃ (<α ₂ ) in the large “light wind” region, and set to α ₄ (<α ₃ ) in the “strong wind” region with the largest amount of air flow. In this way, the larger the amount of air blown by the indoor fan, the lower the set temperature α for preventing dew condensation, so that the margin until dew adheres to the indoor heat exchanger and freezes is about the same. Therefore, the problem of the conventional device that “the dew condensation prevention control at the time of a large air volume is too early, so that the cooling or dehumidifying ability is suppressed low” is solved, and as a result, the cooling ability or dehumidifying ability can be achieved. It is possible to control the antifreezing while keeping it as large as possible. Note that the control circuit 11 is configured to include a microprocessor, and which of the "quiet wind", "light wind", "weak wind" and "strong wind" the blow rate belongs to is the indoor fan at that time. Number of revolutions F
_{In addition} to the determination from _n , the microprocessor is provided with the above-mentioned freeze prevention function.

FIG. 3 is a flow chart showing the processing procedure of the microprocessor for controlling the freeze prevention. Here, first, in step 101, the air volume of the indoor fan (rotational speed F
Depending on _n ), the set temperature α for preventing dew condensation is determined to be _one of α ₁ , α ₂ , α ₃ and α ₄ shown in FIG. 1 (b). Then, in step 102, the indoor heat exchanger temperature T _E detected by the temperature sensor 14 is read. Then, step 10
3 indoor heat exchanger temperature T _E is determined whether the following set temperature T _C4 antifreeze during temperature fall at the indoor heat exchanger temperature T in step 104 when it is not less than the set temperature T _C4 antifreezing _It is determined whether _E is less than or equal to the set temperature α for preventing dew condensation, and if it is not less than the set temperature α for dew condensation prevention, in step 105, the target value of the compressor frequency Hz set in advance is directly set to the inverter device 10. In addition, the following steps 101-
Continue the process of 105 and execute the control of the normal operation zone.

Next, when the indoor heat exchanger temperature T _E becomes equal to or lower than the dew condensation prevention set temperature α by operating the compressor 1 at the target rotation speed, after performing the processing of step 104 In step 106 of the above, the upper limit of the target value of the compressor frequency Hz for the inverter device 10 is selected by operating one of the values set in a stepwise manner according to the air flow rate as shown in FIG. 5 (b). Yes, shift to dew condensation prevention zone operation. In this case, the indoor heat exchanger temperature T _E is read in step 107, and the indoor heat exchanger temperature T _E is read in step 108.
Determine whether _E has recovered above the set temperature (α + β) for preventing dew condensation. Here, the set temperature (α +
If it has recovered above β), the normal operation zone is restored by the processing of steps 101-105. On the other hand, step 108
The indoor heat exchanger temperature T _E is the set temperature (α
When it is determined that the temperature is not higher than + β), it is determined in step 109 whether or not the indoor heat exchanger temperature T _E is the freezing prevention set temperature T _C4 or less, and it is determined that it is not the set temperature T _C4 or less. For example, the operation of the dew condensation prevention zone is continued based on the processing of steps 106 to 109. Despite this operation, the indoor heat exchanger temperature T _E decreases, and when it is determined in step 109 that the indoor heat exchanger temperature T _E has become equal to or lower than the set temperature T _{C4 for} freeze prevention, the step 110 Perform the following processing. In step 103, the indoor heat exchanger temperature T
_When it is determined that _E has become equal to or lower than the set temperature T _C4 for freeze prevention, the processing in step 110 and thereafter is also executed.

In step 110, the compressor frequency Hz is lowered by a predetermined value when a certain time has elapsed, the operation is performed, the indoor heat exchanger temperature T _E is read in the next step 111, and the indoor heat exchange is executed in step 108. It is determined whether or not the vessel temperature T _E has recovered above the set temperature T _{C3 for} freeze prevention. If the indoor heat exchanger temperature T _E has not recovered to the freezing prevention set temperature T _C3 or more, the steps 110 to 112 are repeated, and the compressor frequency Hz is lowered by a predetermined value each time. Operation in the frozen release zone will continue. On the other hand, if it is determined in step 112 that the indoor heat exchanger temperature T _E has recovered to the freezing prevention set temperature T _C3 or higher, the process returns to the first step 101.

Thus, by the process shown in the flowchart of FIG. 3, as shown in FIG. 5B, the operation is performed while the upper limit of the compressor frequency Hz is set according to the amount of air blown from the indoor fan, and As shown in FIG. 1 (b), it is possible to perform anti-freezing control by shifting to dew-prevention control by using the set temperatures α _{1 to} α ₄ for dew-prevention that decrease stepwise as the amount of blown indoor fan increases. Becomes

It should be noted that in the above embodiment, the "quiet wind", "light wind",
Either "weak wind" or "strong wind" was selected, and the set temperature α for preventing dew condensation was set to a stepwise decrease of α _{1 to} α ₄ according to the setting state. When the air flow rate is continuously variable, α ₅ associated with “quiet wind” and α ₆ associated with “strong wind” are set as shown in FIG. , "Weak wind" on the way
It is also possible to determine α ₇ corresponding to by the interpolation calculation using the fan rotation speed F _n . As a result, the margin until dew adheres to the indoor heat exchanger and reaches freezing can be made approximately the same over the entire range including the midpoint of the variation range of the fan rotation speed.

Also, without dare to perform interpolation calculation,
As the rotation speed of the indoor fan increases, the set temperature for preventing dew condensation linearly decreases, either by using a data table in which these are associated in advance or by using a linear function for calculation. Good.

Furthermore, according to the above-mentioned embodiment, the one provided with the fan air flow rate setting device 12 has been described, but the present invention is not limited to this application, for example, the set room temperature T _S and the temperature sensor. Based on the difference between the detected temperature T _A by 13 and the control circuit 11 "quiet wind", "light breeze",
The present invention can also be applied to a configuration in which either "weak wind" or "strong wind" is automatically selected, or a configuration in which the amount of blown air is continuously variably set.

[0026]

As is apparent from the above description, according to the present invention, in the cooling or dry operation mode, the number of revolutions of the compressor is limited to a predetermined value or less according to the temperature of the indoor heat exchanger. When the antifreezing control is performed, the set temperature for preventing dew condensation is first changed in association with the air flow rate of the indoor fan, so that the cooling capacity or dehumidifying capacity can be maintained as large as possible.

Further, the larger the amount of air blown from the indoor fan, the lower the set temperature for preventing dew condensation, so that the margin until dew adheres to the indoor heat exchanger and freezes up is determined by the total number of fan rotations. The same degree can be achieved over the variation range.

Further, the target number of revolutions of the compressor is set based on the difference between the detected value and the set value of the indoor temperature, and the temperature of the indoor heat exchanger is equal to or lower than the set temperature for preventing dew condensation which is determined by the air flow rate as a parameter. Then, by limiting the target rotation speed, it is possible to easily and surely control.

Further, by setting the set temperature for preventing dew condensation on the basis of the number of revolutions of the indoor fan instead of the amount of blown air, there is also an effect that the antifreezing control is facilitated.

[Brief description of drawings]

FIG. 1 illustrates the operation of one embodiment of the present invention.
The figure which showed the relationship between the indoor heat exchanger temperature and a control zone, and the relationship between the ventilation amount of an indoor fan, and the set temperature of dew prevention.

FIG. 2 is a schematic configuration diagram of an embodiment of the present invention.

FIG. 3 is a flowchart showing a processing procedure of a microprocessor forming a main element of one embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the number of rotations of an indoor fan and a set temperature for preventing dew condensation in order to explain another embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between an indoor heat exchanger temperature and a control zone, and a relationship between an indoor fan rotation speed or an air flow rate and a compressor frequency in order to explain an operation of a conventional air conditioner. .

[Explanation of symbols]

 1 Compressor 2 Outdoor Heat Exchanger 4 Indoor Heat Exchanger 6 Indoor Fan 10 Inverter Device 11 Control Circuit 12 Fan Air Volume Setting Device 13, 14 Temperature Sensor

Claims (7)

[Claims] 1. Air for detecting the temperature of an indoor heat exchanger in a cooling or dry operation mode and limiting the rotational speed of a compressor to a predetermined value or less when the detected temperature falls below a set temperature for preventing dew condensation. An air conditioner comprising: an indoor fan having a variable air flow rate, and changing the set temperature for preventing dew condensation in association with the air flow rate of the indoor fan. 2. The air conditioner according to claim 1, wherein the set temperature for preventing dew condensation is set lower as the amount of air blown by the indoor fan is larger. 3. Further, a temperature detecting means for detecting the indoor temperature and a temperature setting means for setting the indoor temperature are provided, and based on the difference between the temperature detected by the temperature detecting means and the temperature set by the temperature setting means. The air conditioner according to claim 1 or 2, wherein a target rotation speed of the compressor is set. 4. The air conditioner according to claim 3, wherein the air flow rate of the indoor fan is set based on the difference between the temperature detected by the temperature detecting means and the temperature set by the temperature setting means. 5. The air conditioner according to claim 1, further comprising an indoor fan air flow rate setting means capable of manually setting an air flow rate of the indoor fan. 6. When the detected temperature of the indoor heat exchanger becomes equal to or lower than the set temperature for freeze prevention lower than the set temperature for dew condensation prevention, the rotational speed of the compressor is sequentially decreased by a predetermined value at predetermined time intervals. The air conditioner according to any one of claims 1 to 5, wherein 7. The blow rate of the indoor fan is replaced by the rotation speed of the indoor fan.
The air conditioner according to any one of 1.