JPH09273819A - Refrigeration cycle - Google Patents

Abstract

(57) Abstract: In an air conditioner including an inverter-driven compressor and a constant speed compressor, a failure rate of the inverter-driven compressor is reduced, and a highly reliable refrigeration cycle is obtained. SOLUTION: When switching the operation of an inverter driven compressor (105a) and a constant speed compressor (105b), the inverter driven compressor is stopped for a predetermined time (ts), and the time when the inverter driven compressor is stopped ( ts) is operated only by the constant speed compressor (105b).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a refrigeration cycle such as an air conditioner, and is suitable for a refrigerator having an inverter-driven compressor and a constant speed compressor. .

[0002]

2. Description of the Related Art As an air conditioner equipped with an inverter-driven compressor and a constant speed compressor, one disclosed in Japanese Patent Publication No. 5-38217 is known. The operation method of the inverter driven compressor and the constant speed compressor is as follows.

(1) When the air-conditioning load is small, only the inverter-driven compressor is operated, and the drive frequency of the inverter-driven compressor is low.

The driving frequency is increased as the air conditioning load increases. ◆ When the drive frequency of the inverter compressor reaches the maximum frequency and the air conditioning load increases, the constant speed compressor also operates and the drive frequency is reduced to the minimum frequency. ◆ Furthermore, when the air conditioning load increases, the drive frequency of the inverter compressor will be increased again.

(2) When the air conditioning load is large, both the inverter driven compressor and the constant speed compressor are operated, and the drive frequency of the inverter driven compressor is high. ◆ Lower the drive frequency as the air conditioning load decreases. ◆ When the drive frequency becomes the lowest frequency and the air conditioning load decreases, the constant speed compressor also stops and the drive frequency of the inverter compressor is increased to the highest frequency. ◆ Furthermore, when the air conditioning load decreases, the drive frequency of the inverter compressor will be reduced again.

[0006]

According to the method of operating the compressor of the air conditioner described above, the inverter-driven compressor is always in operation while the compressor is operating, and the operating time is significantly longer than that of the constant speed compressor. become longer. Further, the drive frequency of the inverter-driven compressor suddenly changes from the highest frequency to the lowest frequency and from the lowest frequency to the highest frequency. Therefore, the load fluctuation that the inverter-driven compressor receives becomes large. ◆ From the above, there is a problem that the failure rate of the inverter-driven compressor is higher than that of the constant speed compressor.

An object of the present invention is to reduce the failure rate of an inverter-driven compressor and obtain a highly reliable refrigeration cycle.

[0008]

According to the present invention, an inverter driven compressor having a variable drive frequency, a constant speed compressor having a constant drive frequency, a heat source side heat exchanger, and a use side heat exchanger. And a refrigeration cycle having an expansion mechanism, means for switching the operation of the inverter-driven compressor and constant-speed compressor, means for stopping the inverter-driven compressor for a predetermined time when the operation is switched by the switching means, and means for stopping. Means to operate only with the constant speed compressor for the time stopped by.

Here, the means for switching the operation, the means for stopping the operation, and the means for operating only with the constant speed compressor mean controlling stop, start, and capacity of the inverter-driven compressor and the constant speed compressor. However, specifically, it is performed by providing a microcomputer or the like in the outdoor controller.

By stopping the inverter-driven compressor for a fixed time when switching the operation, the operating time of the inverter-driven compressor is relatively reduced, and the operating time is significantly longer than the operating time of the constant speed compressor. Never be.
In addition, the time when the engine is operated near the maximum operating frequency, that is, at full rotation can be reduced.

Further, according to the present invention, the means for switching the operation of the inverter driven compressor and the constant speed compressor, and the constant speed compressor are switched to the operation and the inverter driven compressor is stopped by the switching means to further increase the capacity. In this case, a stopping means for stopping the inverter-driven compressor and a switching means until the required frequency corresponding to the required capacity of the inverter-driven compressor corresponds to a value higher by a predetermined frequency than the minimum frequency for driving the inverter-driven compressor. The constant-speed compressor is switched to the operation mode and the inverter-driven compressor is stopped to stop the operation.When further reducing the capacity, the constant-speed compressor is stopped and the maximum frequency for driving the inverter-driven compressor is reduced by a predetermined frequency. And a means for driving at a certain value.

When increasing the capacity of the compressor, by stopping the inverter-driven compressor until the required frequency corresponding to the required capacity reaches a value that is higher than the lowest frequency for driving the inverter-driven compressor by a predetermined frequency, When the load fluctuation is smaller than the value corresponding to the predetermined frequency, the inverter-driven compressor can be stopped.

As a result, frequent start / stop of the inverter-driven compressor can be suppressed and reliability can be improved.

Further, by operating only the constant speed compressor during the time when the inverter driven compressor is stopped in the above, it is possible to sufficiently adapt to the load fluctuation during that time.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the configuration of a refrigeration cycle, FIG. 2 is a line graph illustrating the capacity of a compressor with respect to a required capacity, FIG.
FIG. 4 is a time chart diagram similarly showing a control method of the compressor.

The outdoor unit 100 and the two indoor units 200, 30
0 is connected by a gas pipe 121 and a liquid pipe 122. The outdoor unit 100 includes a compressor 105, a four-way valve 106,
The outdoor heat exchanger 101, the outdoor refrigerant flow control valve 102, the outdoor fan 103, the accumulator 104, the receiver 106.
And an outdoor controller 151.

The compressor 105 is provided with two inverter compressors 105a whose motor rotation speed is variable and a constant speed compressor 105b whose motor rotation speed is constant. Outdoor controller 15
1 is an inverter compressor 105a and a constant speed compressor 105
b on / off (operation and stop), inverter compressor 10
The rotation speed of the motor 5a and the valve opening degree of the outdoor refrigerant flow rate adjusting valve 102 are controlled.

The indoor unit 200 includes an indoor heat exchanger 201, an indoor refrigerant flow rate adjusting valve 202, an indoor fan 203, a temperature detector 204 for detecting the intake air temperature, and an indoor controller 2.
It is composed of 08. A signal from the temperature detector 204 is input to the indoor controller 208, and the indoor controller 208 controls the opening degree of the indoor refrigerant flow rate adjusting valve 202.

The indoor unit 300 includes an indoor heat exchanger 301, an indoor refrigerant flow rate adjusting valve 302, an indoor fan 303, a temperature detector 304 for detecting the intake air temperature, and an indoor controller 3.
It is composed of 08. A signal from the temperature detector 304 is input to the indoor controller 308, and the indoor controller 308 controls the opening degree of the indoor refrigerant flow rate adjustment valve 302. ◆ The indoor controller 208, 308 and the outdoor controller 151 are the transmission line 1
It is connected by 23.

The flow of the refrigerant during the cooling operation will be described. Solid arrows shown in the gas pipe 121 and the liquid pipe 122 indicate the refrigerant flow direction, and solid arrows in the indoor units 200 and 300 indicate the air flow direction.

The refrigerant discharged from the compressor 105 passes through the four-way valve 106 and enters the outdoor heat exchanger 101, where it is heat-exchanged with the outdoor air sent by the outdoor fan 103 and condensed. After that, the condensed refrigerant enters the receiver 107 through the fully opened outdoor refrigerant flow rate adjusting valve 102, is separated into gas and liquid, and the liquid refrigerant exits the outdoor unit 100, enters the liquid pipe 122, and enters the indoor units 200 and 300. Sent. The liquid refrigerant entering the indoor unit 200 is decompressed by the indoor refrigerant flow rate adjustment valve 202,
The heat enters the indoor heat exchanger 201, is heat-exchanged with the indoor air sent by the indoor fan 203, and evaporates. At this time, the indoor air is cooled and blown out from the indoor unit 200.

The evaporated refrigerant exits the indoor unit 200. On the other hand, the refrigerant that has entered the indoor unit 300 is the same as the indoor unit 200 described above.
Similarly, the indoor refrigerant flow rate control valve 302 reduces the pressure, enters the indoor heat exchanger 301, exchanges heat with the indoor air sent by the indoor fan 303, and evaporates. At this time, the indoor air is cooled and blown out from the indoor unit 300. The evaporated refrigerant exits the indoor unit 300, merges with the refrigerant that exits from the indoor unit 200, passes through the gas pipe 121, and passes through the outdoor unit 100.
Sent to The refrigerant that has entered the outdoor unit 100 is a four-way valve 10.
6. It is sucked into the compressor 105 through the accumulator 104, compressed, and discharged again.

Next, the flow of the refrigerant during the heating operation will be described. Broken line arrows shown in the gas pipe 121 and the liquid pipe 122 indicate the flow direction of the refrigerant. The refrigerant discharged from the compressor 105 passes through the four-way valve 106 and enters the gas pipe 121,
It is sent to the indoor units 200 and 300. The refrigerant that has entered the indoor unit 200 enters the indoor heat exchanger 201, and the indoor fan 203
Is condensed by being exchanged with the indoor air sent by. At this time, the room air is warmed.

Thereafter, the condensed refrigerant exits the indoor unit 200 through the indoor refrigerant flow rate adjusting valve 202. On the other hand, indoor unit 3
The refrigerant entering 00 also condenses like the indoor unit 200 and exits the indoor unit 300. The refrigerants that have exited the indoor units 200 and 300 merge and enter the outdoor unit 100 through the liquid pipe 122. The refrigerant that has entered the outdoor unit 100 first enters the receiver 107 for gas-liquid separation, and the liquid refrigerant exits the receiver 107 and is decompressed by the indoor refrigerant flow rate adjustment valve 102, and the outdoor heat exchanger 1
01, the heat is exchanged with the outdoor air sent by the outdoor fan 103 to evaporate, and is sucked into the compressor 105 through the four-way valve 106 and the accumulator 104, compressed, and discharged again.

Next, the operation of the compressor 105 will be described. The outdoor controller 151 calculates the required capacity of the compressor 105 from the difference between the set temperature of the indoor temperature of the indoor units 200 and 300 and the intake air temperature, and the inverter controller 1
05a and the constant speed compressor 105b are controlled. 2 and 3 show the control method.

The basic compression functional force control will be described with reference to FIG. (1) When the required capacity of the compressor 105 is small, only the inverter compressor 105a is operated and the drive frequency is the lowest frequency.

(2) As the required capacity of the compressor 105 increases, the drive frequency is increased to the maximum frequency. At the same time, the operation of the constant speed compressor 105b is started and the drive frequency of the inverter compressor 105a is changed. Lower to the lowest frequency.

(3) Further, when the required capacity of the compressor 105 becomes large, the drive frequency of the inverter compressor 105a can be increased again to the maximum frequency.

(4) When the required capacity of the compressor 105 is reduced, the drive frequency of the inverter compressor 105a is reduced, and when it is reduced to the minimum frequency, the constant speed compressor 105 is reduced.
b is stopped and the drive frequency of the inverter compressor 105a is increased to the maximum frequency.

(5) Further, when the required capacity of the compressor 105 becomes smaller, the drive frequency of the inverter compressor 105a is again reduced to the minimum frequency.

Next, the capacity control of the compressor according to the embodiment will be described with reference to FIGS. 3 and 4. The difference from FIG. 2 is when switching the number of compressors in which the constant speed compressor is turned on and off.

(1) When the required capacity of the compressor 105 is small, the inverter compressor 105a is operated, the constant speed compressor is stopped, and the drive frequency of the inverter compressor 105a is the lowest frequency. .

(2) As the required capacity of the compressor 105 increases, the drive frequency is increased to the maximum frequency, and the constant speed compressor 105b is operated at the same time.
The time t set in advance for the inverter compressor 105a
Stop for s.

(3) After that, the inverter compressor 105a is operated at a drive frequency suitable for the required capacity of the compressor 105.

(4) Further, when the required capacity of the compressor 105 is increased, the drive frequency of the inverter compressor 105a is increased again and the maximum frequency is increased.

(5) When the required capacity of the compressor 105 becomes smaller, the drive frequency of the inverter compressor 105a is reduced, and when it is reduced to the minimum frequency, the inverter compressor 1
05a is stopped for a preset time ts. While the inverter compressor 105a is stopped, only the constant speed compressor 105b is operated.

(6) After the time ts has elapsed, the constant-speed compressor 105b is stopped, and at the same time, the inverter compressor 105a is driven at a drive frequency corresponding to the required capacity of the compressor 105.
To drive.

(7) Further, when the required capacity of the compressor 105 becomes smaller, the drive frequency of the inverter compressor 105a is reduced again.

Next, description will be made with reference to FIG. FIG. 4A shows the control when the required capacity to the compressor 105 rises from small to medium and the required capacity to the compressor 105 decreases when switching the number of compressors. .

(1) When the required capacity of the compressor 105 is small, the inverter compressor 105a is operated, the constant speed compressor is stopped, and the drive frequency of the inverter compressor 105a is the lowest frequency.

(2) As the required capacity of the compressor 105 increases, the drive frequency is increased to the maximum frequency, and at the same time the constant speed compressor 105b is operated,
The inverter compressor 105a is stopped.

(3) After that, although the required capacity of the compressor 105 decreases, the inverter compressor 105a is stopped for a preset time ts and is operated only by the constant speed compressor 105b.

(4) After the time ts has elapsed, the constant speed compressor 105b is stopped and at the same time, the inverter compressor 10
5a is operated at a drive frequency suitable for the required capacity of the compressor 105.

FIG. 4B shows the control when the required capacity to the compressor 105 is reduced from large to medium and the required capacity to the compressor 105 is increased when the number of compressors is switched. It is a thing.

(1) When the required capacity of the compressor 105 is large, the inverter compressor 105a and the constant speed compressor 105
The driving frequency of the inverter compressor 105a is the highest frequency when the motor driving motor is driven.

(2) As the required capacity of the compressor 105 becomes smaller, the drive frequency is reduced to the lowest frequency, and the inverter compressor 105a is stopped and only the constant speed compressor 105b is operated.

(3) After that, although the required capacity of the compressor 105 increases, the inverter compressor 105a is stopped for a preset time ts and is operated only by the constant speed compressor 105b.

(4) After the time ts has elapsed, the inverter compressor 105a is operated at a drive frequency that matches the required capacity of the compressor 105.

Next, the capacity control of the compressor according to another embodiment will be described with reference to FIGS. FIG. 5 is a time chart showing a method of controlling a compressor used in a refrigeration cycle of another embodiment, and FIG. 6 is a time chart showing a method of controlling the compressor. The difference from the basic control of FIG. 2 is when the number of compressors is switched on and off when the constant speed compressor is turned on and off.

First, description will be made with reference to FIG. When the required capacity of the compressor 105 is small, the inverter compressor 105a is operated, the constant speed compressor is stopped, and the drive frequency of the inverter compressor 105a is the lowest frequency.

(1) As the required capacity of the compressor 105 increases, the driving frequency is increased to the maximum frequency, and the constant speed compressor 105b is operated at the same time.
The inverter compressor 105a is stopped.

(2) The stop of the inverter compressor 105a continues until the command frequency to the inverter compressor 105a becomes higher than the minimum frequency by fs1.

(3) When the command frequency to the inverter compressor 105a becomes larger than the minimum frequency by fs1,
The inverter compressor 105a is operated at a drive frequency of (minimum frequency + fs1).

(4) Further, when the required capacity of the compressor 105 is increased, the drive frequency of the inverter compressor 105a is increased again to the maximum frequency.

(5) When the required capacity of the compressor 105 becomes small, the drive frequency of the inverter compressor 105a is decreased, and when it is decreased to the minimum frequency, the inverter compressor 1
05a is stopped and only the constant speed compressor 105b is operated.

(6) The stop of the inverter compressor 105a continues until the command frequency to the inverter compressor 105a becomes smaller than the maximum frequency by fs2.

(7) When the command frequency to the inverter compressor 105a becomes smaller than the maximum frequency by fs2,
At the same time as stopping the constant speed compressor 105b, the inverter compressor 105a is operated at a drive frequency of (maximum frequency-fs2).

(8) Further, when the required capacity of the compressor 105 becomes smaller, the drive frequency of the inverter compressor 105a is reduced again.

Next, description will be made with reference to FIG. FIG. 6A shows the control when the required capacity to the compressor 105 rises from small to medium and the required capacity to the compressor 105 decreases when switching the number of compressors. .

(1) When the required capacity of the compressor 105 is small, the inverter compressor 105a is operated, the constant speed compressor is stopped, and the drive frequency of the inverter compressor 105a is the lowest frequency.

(2) As the required capacity of the compressor 105 increases, the driving frequency is increased to the maximum frequency, and the constant speed compressor 105b is operated at the same time.
The inverter compressor 105a is stopped.

(3) After that, even if the required capacity of the compressor 105 decreases, the inverter compressor 105a remains stopped and only the constant speed compressor 105b is operated.

(4) The stop of the inverter compressor 105a continues until the command frequency to the inverter compressor 105a becomes smaller than the maximum frequency by fs2.

(5) When the command frequency to the inverter compressor 105a becomes smaller than the maximum frequency by fs2,
At the same time as stopping the constant speed compressor 105b, the inverter compressor 105a is operated at a drive frequency of (maximum frequency-fs2).

(6) Further, when the required capacity of the compressor 105 becomes smaller, the drive frequency of the inverter compressor 105a is decreased.

FIG. 6B shows the control when the required capacity of the compressor 105 is reduced from large to medium and the required capacity of the compressor 105 is increased when the number of compressors is switched. It is a thing.

(1) When the required capacity of the compressor 105 is large, the inverter compressor 105a and the constant speed compressor 105
Both are operated, and the drive frequency of the inverter compressor 105a is the highest frequency.

(2) As the required capacity of the compressor 105 becomes smaller, the drive frequency is reduced to the lowest frequency, and the inverter compressor 105a is stopped and only the constant speed compressor 105b is operated.

(3) After that, even if the required capacity of the compressor 105 increases, the inverter compressor 105a remains stopped and only the constant speed compressor 105b is operated.

(4) The stop of the inverter compressor 105a is continued until the command frequency to the inverter compressor 105a becomes higher than the minimum frequency by fs1.

(5) When the command frequency to the inverter compressor 105a exceeds the minimum frequency by fs1,
The inverter compressor 105a is operated at a drive frequency of (minimum frequency + fs1).

(6) Further, when the required capacity of the compressor 105 increases, the drive frequency of the inverter compressor 105a is increased.

[0073]

According to the present invention, the operating time of the inverter-driven compressor is reduced, and the failure rate of the inverter-driven compressor is reduced accordingly, and a highly reliable refrigeration cycle is provided. Further, since the inverter-driven compressor is stopped when the ratio of the inverter-driven compressor to the required capacity of the compressor is small, the influence on the load can be reduced.

Further, the refrigeration cycle according to the present invention can reduce the operating time of the inverter-driven compressor to suppress frequent start-stop of the inverter-driven compressor and reduce the failure rate even when the load fluctuation is large. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a refrigeration cycle.

FIG. 2 is a line graph illustrating a compressor capacity with respect to a required capacity.

FIG. 3 is a time chart showing a method of controlling the compressor used in the refrigeration cycle according to the present invention.

FIG. 4 is a time chart showing a method of controlling the compressor according to the embodiment.

FIG. 5 is a time chart diagram showing a control method of a compressor used in a refrigeration cycle.

FIG. 6 is a time chart showing a method of controlling a compressor according to another embodiment.

[Explanation of symbols]

100 ... Outdoor unit, 101 ... Outdoor heat exchanger, 102 ... Outdoor refrigerant flow rate adjusting valve, 105 ... Compressor, 105a ... Inverter compressor, 105b ... Constant speed compressor, 121 ... Gas pipe, 122 ... Liquid pipe, 151 ... Outdoor controller, 200, 3
00 ... Indoor unit, 201, 301 ... Indoor heat exchanger, 20
2, 302 ... Indoor refrigerant flow control valve, 208, 308 ... Indoor controller.

Claims (3)

[Claims] 1. A refrigeration cycle having an inverter-driven compressor whose drive frequency is variable, a constant speed compressor whose drive frequency is constant, a heat source side heat exchanger, a use side heat exchanger, and an expansion mechanism. In, the means for switching the operation of the inverter driven compressor and the constant speed compressor, a means for stopping the inverter driven compressor for a predetermined time when switching the operation by the switching means, and a means for stopping by the means for stopping. And a means for operating only the constant speed compressor for a certain period of time. 2. A refrigeration cycle having an inverter driven compressor whose drive frequency is variable, a constant speed compressor whose drive frequency is constant, a heat source side heat exchanger, a utilization side heat exchanger and an expansion mechanism. In the means for switching the operation of the inverter driven compressor and the constant speed compressor, the constant speed compressor is switched to the operation and the inverter driven compressor is stopped by the switching means, when further increasing the capacity. Stopping means for stopping the inverter-driven compressor until the required frequency corresponding to the required capacity of the inverter-driven compressor corresponds to a value that is higher than the lowest frequency for driving the inverter-driven compressor by a predetermined frequency, The constant speed compressor is switched to the operation by the switching means, and the inverter driven compressor is switched to the stop, A refrigerating cycle, comprising means for stopping the constant-speed compressor and further operating the inverter-driven compressor at a value smaller than a maximum frequency for driving the inverter-driven compressor by a predetermined frequency when the capacity is further reduced. 3. The refrigerating cycle according to claim 2, wherein only the constant speed compressor is operated during the time stopped by the stopping means.