JP2663792B2 - Operation control device for air conditioner - Google Patents

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 an indoor air outlet during a cooling operation.
And improvement measures for preventing dew condensation .

[0002]

2. Description of the Related Art Conventionally, during cooling operation of an air conditioner,
When the humidity in the room is high, dew condensation occurs around the air outlet, and there are phenomena such as condensation water dripping into the room and white fog.

[0003] In order to prevent such dew condensation, due to the mechanical structure of the air conditioner, hair is implanted around the air outlet to increase the surface area and to enhance the water-capturing power by utilizing the capillary phenomenon. For example, measures have been taken to enhance the airflow and prevent the cool air from coming into contact with the warm air by improving the airflow.

On the other hand, as disclosed in Japanese Utility Model Application Laid-Open No. 64-8146, for example, during the cooling operation of the air conditioner, the relative humidity of the intake air is detected, and when the relative humidity reaches a predetermined value or more, It is a known technique to prevent the exposure of the operation control of the air conditioner from occurring by raising the temperature of the blown air or the evaporation temperature of the refrigerant by controlling the fan air volume or the refrigerant circulation amount.

Further, as disclosed in Japanese Patent Application Laid-Open No. 4-98038, the dew point temperature of the indoor suction air is determined from the evaporation temperature of the indoor heat exchanger during the cooling operation, the indoor suction air temperature and the outdoor suction air temperature. And calculates the degree of dew from the temperature difference between the dew point temperature and the blown air temperature, calculates the time integral of the degree of dew, and stops the compressor when the integrated value becomes higher than a predetermined value. A known technique is to increase the evaporation temperature of the indoor heat exchanger by reducing the operating capacity of the compressor, thereby preventing the occurrence of dew.

[0006]

However, when the dew condensation is to be prevented by the mechanical configuration of the air conditioner as in the above-mentioned conventional one, there is a restriction in design and an increase in manufacturing cost. Become.

Further, in the case of performing control for detecting the humidity and preventing the dew condensation as in the above-mentioned publication, there is a problem that the installation of an expensive humidity sensor also increases the cost.

On the other hand, according to the latter publication, the amount of water condensed is estimated from the relationship between the temperature of the blown air and the temperature of the intake air on the psychrometric chart, and the state in which dew condensation may occur is detected. Therefore, the anti-dewing operation is performed in advance, and there is an advantage that a countermeasure against the dew can be taken at low cost.

However, in this case, since the capacity of the compressor is not taken into account in the calculation of the degree of dew condensation and in the judgment of stopping and reducing the capacity of the compressor, the compressor equipped with the inverter has the advantage. There was regret that it was not fully utilized.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an air conditioner having a compressor whose frequency is variably adjusted by an inverter in an air conditioner having a wet bulb temperature in consideration of an inverter frequency. By calculating the entry of the dew point avoidance control directly from the value of the dew point temperature calculated based on the wet bulb temperature and the like, it is possible to quickly perform the dew point avoidance according to the change in the operating state. is there.

[0011]

In order to achieve the above-mentioned object, the present invention provides a compressor (1) whose operating frequency is variably adjusted by an inverter, as shown in FIG. It is assumed that the air conditioner includes a refrigerant circuit (9) formed by connecting an outdoor heat exchanger (3), a pressure reducing mechanism (5), and an indoor heat exchanger (6).

[0013] As an operation control device of the air conditioner, indoor cooling temperature detecting means (Thr) for detecting the temperature of the suction air of the indoor heat exchanger (6) during cooling operation, and the refrigerant circuit (9). Evaporating temperature detecting means (The) for detecting the evaporating temperature of the refrigerant in the evaporator, and the evaporating temperature detecting means (The)
And the output of the evaporating temperature detecting means (The) to calculate the wet-bulb temperature of the suction air based on the evaporating temperature of the refrigerant and the inverter frequency. An outlet temperature calculating means (51) for calculating the indoor air temperature based on the temperature; a wet bulb temperature calculated by the wet bulb temperature calculating means (50); and a chamber detected by the indoor suction temperature detecting means (Thr). A dew point calculating means (52) for calculating a suction dew point temperature based on the inner suction air temperature;
A dew point calculating unit calculates a dew point based on a temperature difference between the dew point temperature of the indoor intake air calculated by the dew point calculating means (52) and the indoor air temperature calculated by the outlet temperature calculating means (51). Calculating means (53); and frequency control means (54) for controlling the inverter frequency to be reduced when the degree of exposure calculated by the degree of exposure calculating means (53) during cooling operation is higher than a set value. Is provided.

Means taken by the invention of claim 2 is claim 1
In the invention of the above, as shown by the broken line in FIG. 1, a control region limiting means (55) for inhibiting reduction of the inverter frequency by the frequency control means (54) is provided in a region where the inverter frequency is equal to or lower than a predetermined frequency. is there.

A third aspect of the present invention is the above-mentioned first or second aspect of the present invention, wherein the frequency control means (54) switches a set value for determining whether to reduce the frequency. Is provided.

The means implemented by the invention of claim 4 is the control area limiting means (5) according to the invention of claim 1, 2, or 3.
5) is provided with a restricted area switching means (SWwet) for switching a predetermined frequency value for inhibiting the frequency reduction.

[0016]

With the above arrangement, in the first aspect of the invention, the wet-bulb temperature calculating means (50) calculates the wet-bulb temperature of the intake air based on the evaporation temperature and the inverter frequency. Accordingly, the dew point temperature of the suction air is calculated based on the wet bulb temperature and the indoor suction air temperature. The blow-out air temperature is calculated by the blow-out temperature calculating means (51) based on the evaporation temperature, and the degree of dew-degree calculation is performed.
According to 3), the degree of exposure of the indoor heat exchanger (6) is calculated from the difference between the dew point temperature and the outlet air temperature. When the degree of exposure exceeds the set value, the inverter frequency is reduced by the frequency control means (54), so that the amount of evaporation decreases due to a decrease in the amount of circulating refrigerant, and the evaporation temperature rises quickly, and Is prevented from occurring.

In this case, when the wet-bulb temperature is calculated by the wet-bulb temperature calculating means (50), not only the evaporation temperature of the refrigerant but also the inverter frequency is taken into consideration. This is a more accurate index.
Therefore, it is possible to determine whether or not there is a possibility that dew may occur directly from the degree of dew, without the need for time and labor as in the case of controlling the capacity of the compressor (1) based on the time integral of the degree of dew. Dew avoidance control is performed.

According to a second aspect of the present invention, in the first aspect of the present invention, the control area limiting means (55) reduces the frequency for avoiding the dew by the frequency control means (54) in an area below a predetermined frequency. Since the control is prohibited, it is possible to prevent a shortage of capability due to the entry into the exposure avoidance control in a region where the possibility of occurrence of the exposure is extremely small.

According to the third aspect of the present invention, the set value switching means (S
Since the set value of the entry determination to the dew avoidance control is switched by Wwet), the entry determination to the appropriate frequency reduction control according to the situation of the installation location such as a humid location is performed.

According to the fourth aspect of the present invention, the restriction area is switched by the control area restriction means (55) by the restriction area switching means (SWwet) so that the control enters the dew control under an environment where dew is likely to occur. While banned areas have been relaxed,
In an environment where dew is hard to occur, the capacity is maintained high, and the balance between the two is well maintained.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

FIG. 2 shows a refrigerant piping system of an air conditioner according to an embodiment of the present invention. A scroll compressor (1) whose operating frequency is variably adjusted by an inverter (not shown), and a cooling type compressor during cooling operation. A four-way switching valve (2) that switches during heating operation as indicated by the broken line in the figure, as indicated by the solid line in the figure;
An outdoor heat exchanger (3) functioning as a condenser during a cooling operation and an evaporator during a heating operation, a receiver (4) for storing a liquid refrigerant, and an electric expansion valve (5) for reducing the pressure of the refrigerant. An indoor heat exchanger (6) functioning as an evaporator during the cooling operation and as a condenser during the heating operation is arranged, and the above devices are sequentially connected by a refrigerant pipe (8), and heat is transferred by circulation of the refrigerant. Is formed in the refrigerant circuit (9).

The liquid line of the refrigerant circuit (9) includes a point (P) on the upstream side of the receiver (4) and a point (Q) on the downstream side of the electric expansion valve (5), and the indoor heat exchanger (6). ) And a point (S) communicating with the outdoor heat exchanger (3) in a bridge-like manner via a check valve or the like. . The rectification mechanism (2
0), between the points (P) and (S), a first check valve (D1) allowing only the flow of the refrigerant from the outdoor heat exchanger (3) to the receiver (4). Through the first inlet pipe (8
According to b1), between the points (P) and (R), the second check valve (D2) allowing only the flow of the refrigerant from the indoor heat exchanger (6) to the receiver (4). Through the second inflow pipe (8b
According to 2), while being connected to each other, between the points (Q) and (R), only the refrigerant flowing from the electric expansion valve (5) side to the indoor heat exchanger (6) side is allowed. 3 Between the point (Q) and the point (S) from the electric expansion valve (5) side to the outdoor heat exchanger (3) side by the first outflow pipe (8c1) via the three check valve (D3). Through a second outlet pipe (8c2) via a fourth check valve (D4) that allows only the flow of refrigerant to
Each is connected. That is, in each of the cooling and heating cycles, the refrigerant is rectified so as to flow in the order of the condenser (3 or 6), the receiver (4), the electric expansion valve (5), and the evaporator (6 or 3).

A gas bypass passage (4a) for bypassing gas refrigerant from the upper part of the receiver (4) to the liquid pipe between the electric expansion valve (5) and the point (Q) is provided via an on-off valve (SV). When the on-off valve (SV) is opened when the liquid refrigerant needs to be stored in the receiver (4), the refrigerant pressure in the receiver (4) is reduced, and the refrigerant storage in the receiver (4) is performed. The ability is maintained.

In the above embodiment, the accumulator is not provided in the suction pipe of the compressor (1), and the outdoor heat exchanger (3) and the compressor (1) are used during the cooling operation, and the indoor heat exchanger is used during the heating operation. It has a structure in which the exchanger (6) and the compressor (1) are directly connected, that is, an accumulator-less structure in which the evaporator and the compressor (1) are directly connected.

Further, sensors are provided in the air conditioner, (Th2) is disposed in the discharge pipe, a discharge pipe sensor for detecting the discharge pipe temperature, and (Tha) is for the outdoor heat exchanger (3). An outdoor suction sensor disposed at the air inlet and detecting the outside air temperature; (Thc) an external heat exchange sensor disposed at the outdoor heat exchanger (3) and detecting a condensing temperature during cooling operation;
(Thr) is disposed at the air inlet of the indoor heat exchanger (6), and an indoor suction sensor as indoor suction temperature detecting means for detecting the suction air temperature Tr, and (Th) is disposed at the indoor heat exchanger (6). And an internal heat exchange sensor (HPS) as an evaporating temperature detecting means for detecting the evaporating temperature Te during the cooling operation.
Is a high-pressure switch that is turned on when the high-pressure side pressure rises excessively to activate the protection device, and (LPS) is a low-pressure pressure switch that is turned on when the low pressure side pressure is excessively low to activate the protection device.

The signals of the sensors are connected to a controller (10) for controlling the operation of the air conditioner so that the signals can be input to the controller (10). The operation of the harmony device is controlled.

In the refrigerant circuit (9), during cooling operation, liquid refrigerant condensed and liquefied in the outdoor heat exchanger (3) flows in from the first inlet pipe (8b1) and is stored in the receiver (4). After the pressure is reduced by the electric expansion valve (5), the first outflow pipe (8)
After passing through c1), it evaporates in the indoor heat exchanger (6) and the compressor (1)
(Refer to the solid arrow in the figure). During the heating operation, the liquid refrigerant condensed and liquefied in the indoor heat exchanger (6) flows from the second inflow pipe (8b2), and the second check valve ( After being stored in the receiver (4) through D2) and decompressed by the electric expansion valve (5), it is vaporized in the outdoor heat exchanger (3) through the second outflow pipe (8c2) and evaporates in the compressor (1). ) (See dashed arrow in the figure).

Next, the details of the dew condensation avoidance control which is a feature of the present invention will be described with reference to the flowchart of FIG.

First, in step ST1, the wet bulb temperature WB of the suction air temperature (X3) is calculated by the following equation (1) X3 = 19.328 + 1.109 (Te-6) +0.268 (N-Nt) (1) ), The wet bulb temperature WB of the intake air is predicted from the evaporation temperature Te. That is, the evaporation temperature Te is set to “−6” (° C.) in consideration of the pressure loss in the communication pipe between the room and the outside.
And the correction term corresponding to the deviation of the rated frequency from the step value Nt is added to the wet bulb temperature WB (X3).
Is calculated.

Then, in step ST2, the blow-off air temperature To (X4), which is the dry-bulb temperature, is calculated based on the following equation (2) X4 = 7.769 + 1.14 (Te-6) (2) From the evaporation temperature Te to the blown air temperature To
(X4) is predicted. That is, similarly to the case of the wet bulb temperature WB, the calculation of the blown air temperature To taking into account the pressure loss in the communication pipe is performed.

Further, in step ST3, the suction dew point temperature DPT (referred to as X5) is calculated based on the following equation (3) X5 = 1.50 (X3) -0.41Tr-4.45 (3) That is, the wet-bulb temperature W of the suction air
The suction dew point temperature DPT (X5) is predicted from B (X3) and the suction air temperature Tr (X4).

Finally, in step ST4, the degree of exposure DI (referred to as X6) is calculated based on the following equation (4) X6 = X5-X4 (4). That is, finally, by subtracting the blow-off air temperature To (X4) from the suction dew point temperature DPT (X5), the dew degree DI
(X6) is calculated.

Next, a manual dew avoiding changeover switch (S
When Wwet) is on the contact “0” side, that is, under a normal environment, the following control is performed.

That is, in step ST5, the step value N of the inverter frequency is changed to the rated frequency (step value) Nt.
Is determined to be greater than the value obtained by adding “1” to the value, that is, whether the value is greater than the rated step value Nt by “2” or more. In step ST6, it is determined whether X6> 9.0, that is, the exposure It is determined whether or not the degree DPT is larger than the first set value "9.0". If X6> 9.0, it is determined that there is no risk of dew, and the above-described control is repeated without changing the inverter frequency. However, if X6> 9.0, dew is likely to occur. Then, the process proceeds to step ST7, and the droop control for reducing the variable dN6 for changing the inverter frequency to "-1", that is, reducing the step value of the inverter frequency by "1" is performed for the purpose of preventing dew.

On the other hand, a dew avoiding changeover switch (SWwet)
Is in the contact "1" side, that is, in an environment in which dew is likely to occur, such as particularly high humidity, the process proceeds to step ST8, where it is determined whether or not the inverter frequency N is higher than the minimum frequency Nmin. If not, that is, if the inverter frequency is the lowest frequency Nmin, the droop control is avoided and the control returns to step ST1. If N> Nmin, the process proceeds to step ST9 to determine whether X6> 8.0. That is, it is determined whether or not the dew degree DPT is larger than the second set value "8.0" which is smaller than the first set value "9.0". If X6 is not greater than 8.0, it is determined that there is no risk of exposure, and the control returns to step ST1.
When 6> 8.0, it is determined that there is a high possibility that dew will occur, and the process proceeds to step ST7, where the above-described droop control of the inverter frequency is performed.

That is, the changeover switch (SWw
et), by changing the judgment for entering the dew avoiding control, the dew avoiding control (droop control) suitable for the situation of the installation location of the air conditioner is performed.

In the above control flow, step ST
1 controls the wet bulb temperature calculating means (5) according to the present invention.
0) is formed, the blowout temperature calculating means (51) is formed by the control of step ST2, and the dew point calculating means (52) is formed by the control of step ST3.
The control of T4 constitutes the degree-of-dew calculation means (53), and the control of shifting from step ST6 to ST7 constitutes the frequency control means (54).

The control for returning the control from step ST5 constitutes the control area limiting means (55) according to the second aspect of the present invention.

Further, a changeover switch (SWwe
t) has both functions as the set value switching means according to the invention of claim 3 and the restricted area switching means according to the invention of claim 4.

Therefore, in the above embodiment, the wet-bulb temperature calculating means (50) calculates the wet-bulb temperature WB based on the evaporation temperature Te and the step value N of the inverter frequency, and the dew-point calculating means (52) The dew point temperature DPT is calculated based on the wet bulb temperature WB and the indoor suction air temperature Tr. The blow-out air temperature To is calculated by the blow-out temperature calculating means (51) based on the evaporation temperature Te, and the dew degree DI is calculated from the difference between the dew point temperature DPT and the blow-off air temperature To by the dew degree calculating means (53). Is calculated. That is, as shown in the psychrometric chart of FIG. 4, the degree of exposure DI is calculated by the above-described calculation.

Further, the frequency control means (54)
When the degree of dew DI exceeds the set value (9.0 in the above embodiment), the inverter frequency is reduced, so that the amount of evaporation decreases due to the decrease in the amount of circulating refrigerant, and the evaporation temperature Te rises quickly, The occurrence of dew is prevented beforehand.

Here, when the wet-bulb temperature calculating means (50) calculates the wet-bulb temperature WB, not only the evaporation temperature Te of the refrigerant but also the inverter frequency (step value N) is taken into consideration. WB is an index that more accurately represents the current operating state. Therefore, unlike the conventional control, the time integral of the degree of dew is calculated, and depending on the value, there is no need to stop or reduce the capacity of the compressor (1). The control can be executed, and the control can be speeded up.

The control area limiting means (55)
In the case where the range in which the droop control is performed by the frequency control means (54) is limited to a range higher than a predetermined frequency, the capability shortage occurs due to avoiding the dew in a region where the inverter frequency is low and the dew is hard to occur. There is an advantage that can be prevented.

In particular, a changeover switch for avoiding dew condensation (SWwet)
In the case where the air conditioner is installed in a place with high humidity, it is possible to judge appropriate entry into droop control according to the situation of the installation place, and it is possible to exert a remarkable effect. .

In the above embodiment, a single dew-avoidance changeover switch (SWwet) is used to set a set value for judging entry into droop control and a predetermined frequency value for avoiding entry into droop control. Although switching is performed, the present invention is not limited to such an embodiment, and an individual changeover switch may be provided.

[0047]

As described above, according to the first aspect of the present invention, there is provided an operation control device for an air conditioner including a compressor whose operation frequency is variably adjusted by an inverter.
Calculate the wet-bulb temperature of the suction air based on the evaporation temperature and the inverter frequency, calculate the dew point temperature of the suction air based on the wet-bulb temperature and the indoor suction air temperature, and calculate the blow-off air temperature based on the evaporation temperature. Is calculated from the difference between the dew point temperature and the outlet air temperature, and when the degree of exposure exceeds the set value, the inverter frequency is reduced. By judging whether or not there is a possibility of causing direct exposure from the exposure temperature obtained based on the considered wet-bulb temperature, it is possible to perform the exposure avoidance control promptly corresponding to the change in the operating state, Control performance can be improved.

According to the second aspect of the present invention, in the first aspect of the present invention, the region for performing control for avoiding exposure is limited to a region higher than a predetermined frequency, so that dew can occur. Insufficient capacity due to entry into dew avoidance control can be prevented in an area with extremely low performance.

According to the third aspect of the present invention, in the first or second aspect of the present invention, the means for switching the set value for determining the entry into the dew avoidance control is provided. It is possible to make a decision to enter frequency reduction.

According to the invention of claim 4, according to claim 1,
In the second or third aspect of the present invention, the means for switching the frequency range for limiting the entry into the dew avoidance control is provided. In an environment where sticking is unlikely to occur, by maintaining the ability at a high level, a good balance between the two can be maintained, and thus a remarkable effect can be exerted.

[Brief description of the drawings]

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

FIG. 2 is a refrigerant piping system diagram of the air-conditioning apparatus according to the embodiment.

FIG. 3 is a flowchart showing the contents of dew prevention control.

FIG. 4 is a psychrometric chart showing the process of calculating the degree of dew.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Compressor 3 Outdoor heat exchanger 5 Electric expansion valve (pressure reduction mechanism) 6 Indoor heat exchanger 9 Refrigerant circuit 50 Wet bulb temperature calculating means 51 Blow-out temperature calculating means 52 Dew point temperature detecting means 53 Dew degree calculating means 54 Frequency controlling means 55 Control area limiting means Thr Indoor suction sensor (indoor suction temperature detecting means) Thet Heat exchange sensor inside the room (evaporating temperature detecting means) SWwet switch (set value switching means, restricted area switching means)

Claims (4)

(57) [Claims] A refrigerant circuit comprising a compressor (1) whose operation frequency is variably adjusted by an inverter, an outdoor heat exchanger (3), a pressure reducing mechanism (5), and an indoor heat exchanger (6). 9) an indoor air conditioner comprising: an indoor suction temperature detecting means (Thr) for detecting a temperature of suction air of the indoor heat exchanger (6) during a cooling operation; and a refrigerant evaporating in the refrigerant circuit (9). Evaporating temperature detecting means (The) for detecting the temperature; wet bulb temperature calculating means for receiving the output of the evaporating temperature detecting means (The) and calculating the wet bulb temperature of the suction air based on the evaporating temperature of the refrigerant and the inverter frequency. (50), an outlet temperature calculating means (51) for receiving the output of the evaporating temperature detecting means (The) and calculating an indoor air temperature based on the evaporating temperature of the refrigerant; and a wet bulb temperature calculating means (50). Calculated wet bulb temperature and above A dew point calculating means (52) for calculating a suction dew point temperature based on the indoor suction air temperature detected by the inner suction temperature detecting means (Thr); and an indoor suction air calculated by the dew point calculating means (52). A dew degree calculating means (53) for calculating a degree of dew on the basis of a temperature difference between the dew point temperature and the indoor air temperature calculated by the blowing temperature calculating means (51); A frequency control means (54) for controlling the inverter frequency to be reduced when the degree of dew calculated by the calculation means (53) becomes higher than a set value; . 2. The air conditioner operation control device according to claim 1, further comprising: a control region limiting unit that prohibits the frequency control unit from reducing the inverter frequency in a region where the inverter frequency is equal to or lower than a predetermined frequency. An operation control device for an air conditioner, comprising: 3. The operation control device for an air conditioner according to claim 1, further comprising a set value switching means (SWwet) for switching a set value for the frequency control means (54) to determine whether to reduce the frequency. An operation control device for an air conditioner, comprising: 4. The operation control apparatus for an air conditioner according to claim 1, wherein the control area limiting means (55) includes a limiting area switching means (SWwet) for switching a predetermined frequency value for inhibiting frequency reduction. An operation control device for an air conditioner, comprising: