JPH04347440A - Dew formation preventing device of air-conditioner - Google Patents

Abstract

PURPOSE:To perform dew-formation preventing action independent of the rotating speed control of an indoor fan. CONSTITUTION:When a fan motor 6 is operated at a low rotation speed below the LM tap and the evaporation temperature Te of an indoor heat exchanger detected by a first thermistor 3 is 9 deg.C or lower, an indoor microcomputer 5 decides the power source frequency corresponding to the change time/changeless time of a zone, to which cooling load based on the temperature Tr detected by a second thermistor 4 belongs, so that the upper limit of power source frequency of a motor 10 that drives a compressor becomes the specified value. An inverter 9 modulates the power source frequency of the motor 10 based on the frequency signals from the microcomputer 5. Thus, the capacity of an air-conditioner is lowered to perform a dew-formation preventing action independent of the rotating speed control of the indoor fan.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner dew formation avoidance device for avoiding dew formation on an indoor unit of an air conditioner.

0002

[Prior Art] Conventionally, in order to avoid dew formation during cooling in the indoor unit of an air conditioner, the number of rotations of the indoor fan was increased to increase the amount of indoor air supplied to the indoor heat exchanger. I have to.

0003

SUMMARY OF THE INVENTION However, the above-mentioned conventional method for avoiding dew condensation in outdoor units has the following problems. In other words, to avoid condensation, it is necessary to increase the rotation speed of the indoor fan. However,
Increasing the speed of the indoor fan will increase the volume of the air blowing noise, and there is a conflict between avoiding dew formation and reducing the air blowing noise. Therefore, when determining the rotation speed of an indoor fan at the L tap during the prototyping stage, it is necessary to actually rotate the indoor fan and conduct a blowing noise test and a dew formation test to ensure that the blowing noise is below a predetermined volume. The rotation speed must be selected at a speed that is consistent and free of condensation. However, there is no indoor fan rotation speed that satisfies both conditions.

[0004] Therefore, for example, if the indoor fan rotation speed at the L tap is determined with emphasis on avoiding dew formation, the air blowing sound will exceed a predetermined volume. Therefore, it becomes necessary to take soundproofing measures. Furthermore, if the indoor fan rotation speed at the L tap is determined with emphasis on countermeasures against air blowing noise, dew formation cannot be avoided and it becomes necessary to take measures against dew formation. In other words, in either case, the problem arises that a large period of loss and cost increase are inevitable.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a dew formation avoidance device for an air conditioner that can perform dew formation avoidance control independently of indoor fan rotation speed control in an indoor unit.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the invention according to claim 1, as illustrated in FIG. A power supply frequency control means 9 for changing the rotation speed of the electric motor 10, a fan rotation speed detection means for detecting the rotation speed of the fan motor 6 that drives the indoor fan, and a fan rotation speed detection means installed in the indoor heat exchanger for controlling the rotation speed of the indoor heat exchanger. The temperature detection means 3 detects the evaporation temperature, and the indoor heat exchanger detects when the rotation speed of the fan motor 6 detected by the fan rotation speed detection means reaches a predetermined rotation speed range and the temperature detection means 3 detects the temperature detection means 3. It is determined whether or not the evaporation temperature of the vessel has reached a predetermined temperature range, and if the evaporation temperature has reached the predetermined rotation speed range and the predetermined temperature range, the electric motor 1
determining the power supply frequency according to a predetermined rule so that the upper limit of the power supply frequency of 0 becomes a predetermined value lower than normal, and outputting a frequency signal representing the determined power supply frequency to the power supply frequency control means 9; It is characterized by having means 5.

Further, the invention according to claim 2, as illustrated in FIG.
power supply frequency control means 19 for changing the rotation speed of 0, and fan motors 16a, 16b, 16 for driving indoor fans.
c, temperature detection means 13a, 13b, 13c installed in the indoor heat exchanger to detect the evaporation temperature of the indoor heat exchanger, and the fan rotation speed detection means. The detected rotational speed of the fan motors 16a, 16b, 16c reaches a predetermined rotational speed range, and the evaporation temperature of the indoor heat exchanger detected by the temperature detection means 13a, 13b, 13c falls into a predetermined temperature range. If the predetermined rotation speed range and predetermined temperature range are reached, a dummy load is set according to a predetermined rule, and a load signal representing the value of the set dummy load is output. Load setting means 15a, 15
b, 15c, and the load setting means 15a, 15b, 15
power supply frequency determining means for receiving a load signal from c and determining the power supply frequency of the electric motor 20 based on the value of the dummy load, and outputting a frequency signal representing the determined power supply frequency to the power supply frequency control means 19; It is characterized by having 18.

[0008]

In the invention according to claim 1, the rotation speed of the fan motor 6 that drives the indoor fan is detected by the fan rotation speed detection means. On the other hand, the temperature detection means 3 detects the evaporation temperature of the indoor heat exchanger. Then, the power frequency determining means 5 determines that the detected fan motor 6
It is determined whether the rotational speed of the indoor heat exchanger has reached a predetermined rotational speed range and the detected evaporation temperature of the indoor heat exchanger has reached a predetermined temperature range. When the rotation speed reaches the predetermined rotation speed range and the predetermined temperature range, the power supply frequency determining means 5 determines that the electric motor 1 that drives the compressor
The power supply frequency is determined according to a predetermined rule so that the upper limit of the power supply frequency of 0 is a predetermined value lower than normal. Then, a frequency signal representing the determined power supply frequency is output.

The frequency signal outputted from the power supply frequency determining means 5 is inputted to the power supply frequency control means 9. Then, the power supply frequency control means 9 controls the electric motor 1
The power supply frequency with respect to 0 is variably controlled, and the electric motor 1
The rotation speed at 0 is changed. As a result, the upper limit of the rotation speed of the compressor that compresses the refrigerant is also limited to the predetermined value.

[0010] Thus, when the rotational speed of the fan motor is low and the evaporation temperature of the indoor heat exchanger is low, the capacity of the air conditioner is reduced to prevent dew from forming on the indoor unit.

Further, in the invention according to claim 2, the fan rotation speed detection means detects the rotation speeds of the fan motors 16a, 16b, and 16c that drive the indoor fans. On the other hand, the temperature detection means 13a, 13b, and 13c detect the evaporation temperature of the indoor heat exchanger. Then, the load setting means 15a, 15b, 15c causes the detected rotational speed of the fan motors 16a, 16b, 16c to reach a predetermined rotational speed range, and the detected evaporation temperature of the indoor heat exchanger to a predetermined rotational speed range. It is determined whether or not the temperature range has been reached. Then, when it is determined that the predetermined rotational speed range and the predetermined temperature range have been reached, a dummy load is set according to a predetermined rule. Then, a load signal representing this set dummy load is output.

[0012] The load setting means 15a, 15b, 15c
The load signal output from the power supply frequency determining means 18 is inputted to the power supply frequency determining means 18. Then, the power frequency determining means 18 determines the power frequency of the electric motor 20 that drives the compressor based on the value of the dummy load. Then, a frequency signal representing the determined power supply frequency is output. This frequency signal is input to the power supply frequency control means 19. Then, the power frequency control means 19 variably controls the power frequency for the electric motor 20 to change the rotational speed of the electric motor 20. As a result, the rotation speed of the compressor that compresses the refrigerant is limited based on the value of the dummy load, which is different from the actual cooling load.

[0013] In this manner, when the rotational speed of the fan motor is low and the evaporation temperature of the indoor heat exchanger is low, the capacity of the air conditioner is reduced and dew condensation on the indoor unit is prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to illustrated embodiments. <Separate Machine> FIG. 1 is a block diagram of an embodiment in which a dew formation avoidance device is applied to a separate type air conditioner. In FIG. 1, 1 is an indoor unit, and 2 is an outdoor unit. A first thermistor 3 is attached to an indoor heat exchanger (not shown) installed in the indoor unit 1 to detect the evaporation temperature Te of the indoor heat exchanger. Further, a second thermistor 4 for detecting the room temperature Tr is attached to a location exposed to indoor air. The first detection signal and the second detection signal sent from the first thermistor 3 are then
The second detection signal sent from the thermistor 4 is sent to the indoor microcomputer (hereinafter simply referred to as the indoor microcomputer).
Enter 5. This indoor microcomputer 5 stores the RAM (
An electric motor 10 that drives a refrigerant compressor using various information stored in a random access memory (random access memory) 7.
Determine the power frequency.

A frequency signal representing the power supply frequency of the electric motor 10 thus determined is sent to an outdoor microcomputer (hereinafter simply referred to as an outdoor microcomputer) 8 in the outdoor unit 2. The outdoor microcomputer 8 is connected to the electric motor 10
The inverter section 9 variably controls the power frequency of the electric motor 10 to change the rotational speed of the electric motor 10, and controls the power frequency of the electric motor 10 based on the power frequency represented by the input frequency signal to achieve air conditioning. Control the machine's abilities. In addition, the indoor microcomputer 5 sends a command signal based on a setting signal from the outside or a rotation speed set by fan control to a fan motor 6 that drives the indoor fan to drive the indoor fan at the set rotation speed. Rotate with .

[0016] Normally, dew condensation occurs on the indoor unit during cooling. During cooling, the refrigerant compressed by the compressor releases condensation heat in an outdoor heat exchanger (not shown) installed in the outdoor unit 2, and becomes a high-temperature, high-pressure liquid refrigerant. The refrigerant is then depressurized by an expansion valve and evaporated in an indoor heat exchanger to become a gaseous refrigerant. At that time, it absorbs the heat of evaporation from the indoor air to cool the room. After doing so, the gaseous refrigerant returns to the compressor and is compressed again.

In the above-mentioned refrigerant circulation, if the cooling capacity (that is, the heat exchange capacity of the indoor heat exchanger) is too large for the cooling load, the sufficiently low temperature air that has been heat exchanged by the indoor heat exchanger is is blown indoors again by the indoor fan. Therefore, the outlet portion exposed to the hot and humid indoor air is cooled to a sufficiently low temperature. Therefore, near the outlet, the hot and humid indoor air that comes into contact with the wall forming the outlet is condensed and forms dew.

Therefore, in this embodiment, dew formation avoidance control is performed by the indoor microcomputer 5 to avoid dew formation near the air outlet. FIG. 2 is a flowchart of the dew formation avoidance processing operation executed by the indoor microcomputer 5. As shown in FIG. The dew formation avoidance processing operation will be described in detail below with reference to FIG. In step S1, it is determined whether or not the current rotation speed of the indoor fan is a low rotation speed below the LM tap, based on the command signal that the indoor microcomputer 5 itself sends to the fan motor 6. . As a result, if the rotation speed is low below the LM tap, the process proceeds to step S2, and if not, it waits until the rotation speed of the indoor fan becomes below the LM tap. In step S2, based on the first detection signal from the first thermistor 3, it is determined whether the evaporation temperature Te in the indoor heat exchanger is 9° C. or lower. As a result, if the temperature is 9° C. or lower, the process proceeds to step S3. On the other hand, if the temperature is higher than 9°C, the process returns to step S1 and waits until the rotation speed of the indoor fan is below the LM tap and the evaporation temperature Te of the indoor heat exchanger is below 9°C.

In step S3, the room temperature Tr is detected based on the second detection signal from the second thermistor 4. In step S4, the value of the difference between the room temperature Tr detected in step S3 and the target temperature of the room temperature (that is, the cooling load) is calculated, and the zone to which this cooling load value belongs is stored in the RAM 7. You can refer to it and find out. Then, it is determined whether the zone to which the cooling load value at the time of the current sampling belongs has changed from the zone at the time of the previous sampling. As a result, if the zone has changed, the process proceeds to step S6; otherwise, the process proceeds to step S5. In step S5, it is determined whether a predetermined period of time has elapsed since the zone remained unchanged. As a result, if the predetermined time has elapsed, the process advances to step S7; otherwise, the process returns to step S1.

In step S6, the power frequency of the electric motor 10 is determined based on the zone change, and the process proceeds to step S8. In step S7, the electric motor 10
The power frequency of is determined. However, the power supply frequency of the electric motor 10 determined in step S6 or step S7 is a threshold value "F5" which is lower than the normal upper limit value "F8".
"In this way, the capacity of the air conditioner is lowered to prevent an abnormal drop in the wall temperature near the outlet,
This prevents dew build-up near the outlet. In step S8, a frequency signal representing the power supply frequency of the electric motor 10 determined in step S6 or step S7 is output to the outdoor microcomputer 8. Then,
Based on the input frequency signal, the outdoor microcomputer 8
The power frequency of the electric motor 10 is controlled by the inverter section 9 at. In this way, the operation to avoid condensation is started. That is, when the indoor fan rotation speed is low and the evaporation temperature of the indoor heat exchanger is low, it is determined that the dew formation condition has been reached and the dew formation avoidance operation is initiated.

In step S9, based on the first detection signal from the first thermistor 3, it is determined whether the evaporation temperature Te in the indoor heat exchanger is equal to or higher than 11° C., which is the temperature at which the dew formation avoidance operation should be resumed. It is determined whether Result 11
If the temperature is equal to or higher than 0.degree. C., the process proceeds to step S12; otherwise, the process proceeds to step S10. In step S10, based on the command signal sent from the indoor microcomputer 5 to the fan motor 6, it is determined whether the current rotation speed of the indoor fan is equal to or higher than M taps. the result,
If the rotation speed is equal to or higher than M taps, it is determined that no dew formation occurs and the process proceeds to step S12. On the other hand, if it is still less than the ML tap, the process advances to step S11. In step S11, the executed step of step S6 or step S7 is repeated again, and the power supply frequency of the electric motor 10 is determined again. After doing so, the process returns to step S8, and a frequency signal representing the re-determined power frequency of the electric motor 10 is output to the outdoor microcomputer 8.

[0022] In step S12, whether the evaporation temperature Te of the indoor heat exchanger is equal to or higher than the return temperature 11°C, or
Since the rotation speed of the indoor fan is the rotation speed of M tap or more, it is determined that dew formation will no longer occur. Then, the condensation avoidance operation is resumed and normal operation is resumed. In step S13, it is determined whether or not to continue the cooling operation. As a result, if the process is to be continued, the process returns to step S1, and the determination as to whether or not to enter the dew formation avoidance operation is repeated. on the other hand,
If it is not continued, the dew condensation avoidance processing operation is terminated.

FIGS. 3 and 4 show the contents of a table used when determining the power supply frequency of the electric motor 10, which is carried out by the indoor microcomputer 5. FIG. 3 shows the above step S.
FIG. 4 shows the contents of the table when determining the power supply frequency when the zone does not change which is carried out in step S6, and FIG. 4 shows the contents of the table when determining the power supply frequency when the zone changes which is carried out in step S6. Each of these tables is stored in the RAM 7.

FIG. 3 represents the following. That is,
For example, if the rotation speed of the indoor fan is below the LM tap,
In addition, when the evaporation temperature Te of the indoor heat exchanger is 9° C. or less, the power frequency of the electric motor 10 is determined as follows according to the zone to which the current cooling load value belongs. ing. For example, if the current cooling load value belongs to zone C, the power frequency of the electric motor 10 is set to “
Decrease the current power supply frequency by one step within the range from "F5" to "F1".Similarly, in the case of D zone, "F5"
” to “F2”. If in the E zone, increase it by one step within the range from “F3” to “F5.” If in the G zone, the current power frequency The frequency is changed to "F5".In this way, if the rotation speed of the indoor fan is below the ML tap,
When the evaporation temperature of the indoor heat exchanger is 9° C. or lower, the upper limit of the power frequency of the electric motor 10 is kept at “F5”.

FIG. 4 represents the following. That is,
For example, if the rotation speed of the indoor fan is below the LM tap,
In addition, when the evaporation temperature Te of the indoor heat exchanger is 9° C. or less, the power frequency of the electric motor 10 is determined as follows according to the direction of zone change of the cooling load. For example, when the cooling load zone change is a drop from G zone to F zone, the power frequency of the electric motor 10 is changed to “
F4" to "F3". Conversely, if the zone change is an increase from F zone to G zone, the power frequency is increased from "F4" to "F5."
If the zone change is a drop from zone D to zone C, the current power frequency is changed to "F1". In this way, when the rotational speed of the indoor fan is below the ML tap and the evaporation temperature of the indoor heat exchanger is below 9°C, the upper limit of the power frequency of the electric motor 10 is kept at "F5".

[0026] When carrying out the normal operation in step S12 above, the column in FIG. 3 or 4 where the rotational speed of the indoor fan is M taps or more or the column where the evaporation temperature Te of the indoor heat exchanger is higher than 9° C. The power supply frequency of the electric motor 10 is determined based on the contents of .

As a result, as shown in FIG. 5, while the evaporation temperature Te of the indoor heat exchanger falls to 9°C, the electric motor 1
The power supply frequency of 0 is controlled within the range of "F1" to "F8". Then, when the evaporation temperature Te becomes 9℃ or less, “F1
In this way, the temperature near the outlet is increased to avoid dew buildup on the indoor unit.Then, the evaporation temperature Te rises again. When the temperature reaches 11° C., normal operation is resumed and the power supply frequency is again controlled within the range of “F1” to “F8”.

As described above, in this embodiment, the indoor microcomputer 5 provided in the indoor unit 1 controls the rotation speed of the indoor fan to be below the ML tap and the evaporation temperature Te of the indoor heat exchanger to be below 9°C. If so, it is determined that the cooling capacity is too high for the cooling load. In that case, the upper limit of the power frequency of the electric motor 10 that drives the compressor is set to "F5". Therefore, the capacity of the air conditioner can be reduced, an abnormal drop in temperature near the outlet of the indoor unit 1 can be prevented, and dew formation can be avoided. Therefore, even if the indoor fan rotates at a low rotation speed below the LM tap, dew formation can be avoided.

<Multi-type Air Conditioner> FIG. 6 is a block diagram of an embodiment in which the dew formation avoidance device is applied to a multi-type air conditioner. In FIG. 6, reference numerals 11a, 11b, and 11c are indoor units, which are installed in any one of room A, room B, and room C. 12 is an outdoor unit. Each of the above-mentioned indoor units 11a, 11b, 11c is equipped with an indoor heat exchanger (similar to the above-mentioned separate machine).
Thermistor 13a detects the evaporation temperature Te (not shown)
, 13b, 13c, thermistor 13a, 13b, 13c
Indoor microcomputers 15a, 15b forcibly setting the value of the cooling load in the room (A, B, C) based on the detection signal from
, 15c, a fan motor 16a that drives the indoor fan,
16b and 16c are provided.

The outdoor unit 12 also includes an outdoor microcomputer 18 that receives load signals from the indoor microcomputers 15a, 15b, and 15c of the indoor units 11a, 11b, and 11c, and determines the power frequency of the electric motor 20. It is set up. The outdoor microcomputer 18 includes an inverter unit 19 that variably controls the power frequency of the electric motor 20 to change the rotation speed of the electric motor 20, and controls the power frequency of the electric motor 20 based on the determined power frequency to perform air conditioning. Control the machine's abilities. At that time, the outdoor microcomputer 18
determines the power supply frequency of the electric motor 20, for example, in the following manner, based on the load signals input from each of the indoor microcomputers 15a, 15b, and 15c. That is, the total cooling load (that is, the difference between the room temperature Tr and the target temperature) of each room A, B, and C requested by each of the indoor microcomputers 15a, 15b, and 15c is calculated. If the calculated total cooling load is "1° C.", the power frequency of the electric motor 20 is lowered in accordance with the total value. Also,"
If the temperature is 2°C, the power frequency is not changed.Furthermore, if the temperature is 3°C or higher, the power frequency is increased in accordance with the total value.

In this way, each indoor microcomputer 15a, 15
b, 15c are the cooling load values of the corresponding rooms A, B, and C when the rotation speeds of the fan motors 16a, 16b, and 16c and the evaporation temperature Te of the indoor heat exchanger reach dew formation conditions. It is forcibly set to a value corresponding to the evaporation temperature Te, regardless of the actual load. By doing so, the outdoor microcomputer 18 reduces the capacity of the air conditioner. Hereinafter, the cooling load forcibly set in this way will be referred to as a dummy load.

FIG. 7 is a flowchart of the dew formation avoidance processing operation executed by the indoor microcomputer 15a in a certain room (for example, room A). This flowchart is approximately the same as the flowchart of the dew formation avoidance processing operation in the separating machine shown in FIG. However, it differs from the flowchart in FIG. 2 in the following points. That is,
The evaporation temperature Te of the indoor heat exchanger for entering the dew formation avoidance operation determined in step S22 is 14°C. Also,
The evaporation temperature Te of the indoor heat exchanger for returning from the dew formation avoidance operation determined in step S25 is 15°C. Further, the capacity reduction of the air conditioner performed in step S23 is performed by setting a dummy load according to the current evaporation temperature Te of the indoor heat exchanger as described above.

FIG. 8 shows the contents of the table used when setting the dummy load in step S23. This table includes each indoor microcomputer 15a, 15b.
, 15c are stored in the RAMs 17a, 17b, and 17c.

For example, the indoor microcomputer 15a sets the value of the dummy load for room A in the following manner according to the table shown in FIG. That is, the evaporation temperature T of the indoor heat exchanger
As shown in FIG. 9, e decreases to "Te5"=14°C. Then, the indoor microcomputer 15a determines the evaporation temperature Te.
It is determined that the area has entered area B. Then, the value of the dummy load is set to "D5" according to the table shown in FIG. When the evaporation temperature Te further decreases and shifts from region B to region C, the value of the dummy load is changed to "D5".
to “D4 (<D5)”. Similarly below,
As the region of the evaporation temperature Te sequentially shifts from region C to region C, the value of the dummy load is successively reduced from "D4" to "D1." In this way, the evaporation temperature Te becomes 1
When the temperature drops below 4°C, the cooling load value is forcibly limited and the capacity of the air conditioner is reduced. The temperature near the air outlet is then increased to prevent dew from forming on the indoor unit.

Furthermore, the evaporation temperature Te rises again and becomes “
Te2'', the indoor microcomputer 15a determines that the region of the evaporation temperature Te has entered the region E. Then, the value of the dummy load is set to "D" according to the table shown in FIG.
Similarly, as the region of evaporation temperature Te sequentially shifts from region E to region B, the value of the dummy load is sequentially changed from "D2" to "D5". , when the evaporation temperature Te reaches "Te6" = 15°C, the indoor microcomputer 15a determines that it has entered region A (that is, the recovery region).Then, the value of the dummy load is set to "D6".
The normal operation of the electric motor 20 is resumed by setting it to .

As described above, in this embodiment, the indoor microcomputers 15a, 15b, 15c provided in the indoor units 11a, 11b, 11c installed in each room control whether the rotational speed of the indoor fan is below the ML tap. If the evaporation temperature Te of the indoor heat exchanger is 14° C. or lower, it is determined that the cooling capacity is too high. In that case, the cooling load of each room is set to a dummy load depending on the value of the evaporation temperature Te of the indoor heat exchanger, thereby limiting the actual load. Then, the outdoor microcomputer 18 determines the power supply frequency of the motor 20 by referring to the dummy load value input from each indoor microcomputer 15a, 15b, 15c, and the inverter section 19 determines the power frequency of the motor 20 based on the frequency signal from the outdoor microcomputer 18. Controls the power frequency of the electric motor 20. Therefore, the cooling capacity of the air conditioner can be reduced, and an abnormal drop in temperature at the outlet portions of the indoor units 11a, 11b, and 11c can be prevented, and dew formation can be avoided.

As described above, according to each of the above embodiments, dew formation can be avoided independently of the rotation speed control of the indoor fan. Therefore, there is no need to increase the rotation speed of the indoor fan to avoid condensation. As a result, when determining the rotation speed of the indoor fan during the L tap, it is possible to optimally determine the rotation speed of the indoor fan only based on the air blowing sound. Moreover, according to each of the embodiments described above, dew formation can be avoided without providing an external bypass or adding a heat insulating material to reduce the cooling capacity of the air conditioner, so dew formation can be easily avoided at low cost. Furthermore, as described above, the dew formation avoidance device of each embodiment can be applied to air conditioners of any capacity, from small capacity machines such as separate machines to large capacity machines such as multi-purpose machines. .

The power supply frequency determination standard or dummy load value determination standard in this invention is not limited to the determination criteria in each of the above embodiments. Further, the dew formation avoidance processing operation in the present invention is not limited to the above embodiments. In the above embodiment, the dew condensation avoidance operation using the dummy load is applied to a multi-machine, but there is no problem in applying it to a separate machine.

[0039]

Effects of the Invention As is clear from the above, the air conditioner dew formation avoidance device of the invention according to claim 1 has the advantage that the fan motor rotation speed detected by the fan rotation speed detection means falls within a predetermined rotation speed range. and when the evaporation temperature of the indoor heat exchanger detected by the temperature detection means reaches a predetermined temperature range, the power frequency determining means determines that the upper limit of the power frequency for the electric motor that drives the compressor is lower than normal. Determine the above power supply frequency so that it becomes the specified value,
Since the power supply frequency of the electric motor is variably controlled by the power supply frequency control means based on the determined power supply frequency, the performance of the air conditioner can be reduced when the dew formation condition is satisfied. Therefore, dew formation avoidance control can be performed independently of indoor fan rotation speed control in the indoor unit.

[0040] Further, in the dew formation avoidance device for an air conditioner according to the invention according to claim 2, the rotation speed of the fan motor detected by the fan rotation speed detection means reaches a predetermined rotation speed range, and the temperature detection means When the evaporation temperature of the indoor heat exchanger detected by the above reaches a predetermined temperature range, the electric motor drives the compressor by the power supply frequency determining means based on the dummy load set by the load setting means according to a predetermined rule. The power frequency of the motor is determined, and the power frequency of the motor is variably controlled by the power frequency control means based on the determined power frequency, so that the capacity of the air conditioner can be adjusted when the dew formation condition is established. can be lowered. Therefore, dew formation avoidance control can be performed independently of indoor fan rotation speed control in the indoor unit. At that time, the power frequency determining means determines the power frequency of the motor based on the dummy load from the load setting means, so while the load setting means is installed in each of the plurality of indoor units in the multi-machine, By installing the power supply frequency determining means in the outdoor unit, it becomes possible to avoid dew condensation in each indoor unit of the multi-function machine.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of a dew formation avoidance device according to the present invention.

FIG. 2 is a flowchart of a dew formation avoidance processing operation performed by the indoor microcomputer in FIG. 1;

FIG. 3 is a diagram showing an example of a power supply frequency determination standard when no zone changes in FIG. 2;

FIG. 4 is a diagram showing power supply frequency determination criteria when changing zones in FIG. 2;

FIG. 5 is a diagram showing the relationship between the evaporation temperature of the indoor heat exchanger and the power supply frequency range of the electric motor related to the dew formation avoidance processing operation in FIG. 2;

FIG. 6 is a block diagram of an embodiment different from FIG. 1;

FIG. 7 is a flowchart of a dew formation avoidance processing operation executed by each indoor microcomputer in FIG. 6;

FIG. 8 is a diagram showing an example of dummy load setting criteria in FIG. 7;

9 is a diagram showing the relationship between the evaporation temperature of the indoor heat exchanger and its region related to the dew formation avoidance processing operation in FIG. 7; FIG.

[Explanation of symbols]

1, 11a, 11b, 11c...indoor unit, 2, 12
...outdoor unit, 3...first thermistor,
4...Second thermistor, 13a, 13b, 13c,...Thermistor, 5, 15a,
15b, 15c...Indoor microcomputer, 6, 16a, 16b,
16c...Fan motor, 8,18...Outdoor microcomputer,
9, 19... Inverter section, 10, 20... Electric motor.

Claims (2)

[Claims] 1. Power frequency control means (9) for variably controlling the power frequency of an electric motor (10) that drives a compressor that compresses refrigerant to change the rotational speed of the electric motor (10), and driving an indoor fan. fan rotation speed detection means for detecting the rotation speed of the fan motor (6); temperature detection means (3) installed in the indoor heat exchanger for detecting the evaporation temperature of the indoor heat exchanger; The rotation speed of the fan motor (6) detected by the number detection means reaches a predetermined rotation speed range, and the evaporation temperature of the indoor heat exchanger detected by the temperature detection means (3) reaches a predetermined temperature. It is determined whether or not the range has been reached, and if the above-mentioned predetermined rotation speed range and predetermined temperature range have been reached,
The power supply frequency is determined according to a predetermined rule so that the upper limit of the power supply frequency of the electric motor (10) is a predetermined value lower than normal, and a frequency signal representing the determined power supply frequency is transmitted to the power supply frequency control means (9). What is claimed is: 1. A dew formation avoidance device for an air conditioner, characterized in that the dew formation avoidance device for an air conditioner is provided with a power supply frequency determining means (5) that outputs a power frequency. 2. Power frequency control means (19) for variably controlling the power frequency of an electric motor (20) that drives a compressor that compresses refrigerant to change the rotational speed of the electric motor (20), and driving an indoor fan. fan rotation speed detection means for detecting the rotation speed of the fan motors (16a, 16b, 16c); and temperature detection means (13) installed in the indoor heat exchanger for detecting the evaporation temperature of the indoor heat exchanger.
a, 13b, 13c) and the fan motor (16a, 16b,
16c) has reached a predetermined rotation speed range, and whether or not the evaporation temperature of the indoor heat exchanger detected by the temperature detection means (13a, 13b, 13c) has reached a predetermined temperature range. load setting means (15a) that determines the rotation speed and sets a dummy load according to a predetermined rule when the predetermined rotation speed range and the predetermined temperature range are reached, and outputs a load signal representing the value of the set dummy load; ,15b,
15c) and the load setting means (15a, 15b, 15
receiving the load signal from c), determining the power frequency of the electric motor (20) based on the value of the dummy load, and transmitting a frequency signal representing the determined power frequency to the power frequency control means (19); Output power frequency determining means (1
8) A dew formation avoidance device for an air conditioner, characterized by comprising: