JP2000055437A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent temperature-controlling property by preventing indoor temperature fluctuation with a change of the number of operating units of compressors by a method wherein at a time of shifting operation of one unit of the compressor to operation of two units of the compressors according to increase of a cooling load, reheating volume of a reheater is set to maximum once together with starting of a second compressor, and then the reheating volume is allowed to reduce. SOLUTION: When compressors 11, 21 in a first and a second refrigerating cycles are operated, a gaseous refrigerant is liquefied by condensers 12, 22 of an outdoor unit 10, and refrigerant liquid is depressurized by expansion valves 13, 23, then flowing into evaporators 14, 24 of an indoor unit 1, and there absorbing heat from indoor air to evaporate, wherein according to increase of a cooling load (a difference between a detected temperature by an indoor temperature sensor 5 and an indoor setting temperature by an operating controller 6) in a control device, operation of one unit of the compressor 11 is shifted to operation of two units of the compressors 11, 21. At a time of shifting to operation of two units, reheating volume of a reheater 32 is once maximized together with starting of the compressor 21, and from a state of which the reheating volume is allowed to reduce, and capacity of the compressor 11 is controlled to reduce.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner installed in a room that does not like sudden changes in the temperature of blown air, such as a computer room or a communication room.

[0002]

2. Description of the Related Art As a method of performing energy-saving operation of an air conditioner, a variable capacity operation of a compressor using an inverter (output frequency control of the inverter) is known. A negative phase current of a harmonic is generated. Recently, how to deal with these harmonics has become an important issue.

In particular, in the case of an air conditioner having a plurality of compressors, when all the compressors are driven by inverters, there is a problem that the inverter capacity increases and the harmonic reverse-phase current increases.

Accordingly, in an air conditioner having a plurality of compressors, for example, as shown in Japanese Utility Model Application Laid-Open No. 62-12784 (Japanese Utility Model Application No. 60-104512), all of the multiple compressors are driven by an inverter. It is common practice to drive a part of it with commercial power (fixed capacity operation).

On the other hand, as a means for adjusting the temperature of air blown into a room, there is an air conditioner provided with a reheater. That is, the air cooled and dehumidified by the evaporator is warmed by the reheater and then blown into the room. This is a so-called reheat function.

An air conditioner having this reheat function is disclosed in Japanese Patent Application Laid-Open No. 54-154222 (Japanese Patent Application No. 53-6).
2327) and JP-A-3-217744 (Japanese Patent Application No. 2-12906).

[0007] Among them, Japanese Patent Application Laid-Open No. Hei 3-217744 discloses a method in which a plurality of compressors are provided, and when the number of operating compressors is increased, the reheat capability (reheat amount) is set to a maximum. When decreasing, the reheat ability is set to the minimum. In this way, room temperature fluctuations due to changes in the number of operating units are suppressed.

[0008]

The reheat function is excellent in improving the temperature controllability. However, since the heat released to the outside air by the condenser is purposely radiated on the indoor unit side, the energy consumption of the heat is reduced. The feature is that wasteful consumption increases.

In this connection, Japanese Patent Application Laid-Open No. Hei 3-217744 is disclosed.
Although the temperature controllability when the number of operating compressors changes is taken into consideration in the publication disclosed in Japanese Patent Application Laid-Open Publication No. H11-27139, since this is achieved only by the reheat function, the energy consumption increases and the energy saving aspect is reduced. Is not preferred.

[0010] The present invention has been made in view of the above circumstances,
The objective is to obtain sufficient temperature controllability by suppressing room temperature fluctuations due to changes in the number of operating units while ensuring sufficient harmonic countermeasures, and with due consideration given to energy savings. It is an object of the present invention to provide an air conditioner capable of optimal operation.

[0011]

The invention according to claim 1 is
A first refrigeration cycle having a variable capacity first compressor, condenser and evaporator, a second refrigeration cycle having a fixed capacity second compressor, condenser, evaporator and reheater, and an increase in cooling load The operation shifts from the operation of one compressor of the first compressor to the operation of two compressors of the first compressor and the second compressor in response to the decrease in the cooling load. First control means for shifting from the single-unit operation to the single-unit operation of the first compressor; and, when the single-unit operation shifts to the two-unit operation, the reheat amount of the reheater is temporarily increased once the second compressor is started. And the second control means for reducing the reheat amount from the state, and reducing the capacity of the first compressor in accordance with the reduction, and the second control means for shifting from the two-unit operation to the one-unit operation. The amount of reheat of the heater is increased, and with this increase, the capacity of the first compressor is increased, and the amount of reheat is maximized. And a third control means for stopping the second compressor from.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the indoor unit 1 and the outdoor unit 10 are connected by piping to configure an air conditioner of the present invention.

The indoor unit 1 includes a plurality of, for example, two compressors 11 and 21, expansion valves 13 and 23, evaporators (indoor heat exchangers) 14 and 24, a flow control valve 31, a reheater (auxiliary indoor heat). (Exchanger) 32, an indoor fan 2, an inverter 3, and a control device 4. The compressor (first compressor) 11 is a variable displacement type driven by the inverter 3. The compressor (second compressor) 21 is a fixed displacement type driven by a commercial power supply.

The outdoor unit 10 includes a condenser (outdoor heat exchanger) 1
2 and 22 and the outdoor fan 7. A condenser 12 is connected to a refrigerant outlet of the compressor 11 by piping, and an evaporator 14 is connected to the condenser 12 via an expansion valve 13 by piping. Further, the refrigerant suction port of the compressor 11 is connected to the evaporator 14 by piping. Thereby, a first refrigeration cycle is configured.

On the other hand, a condenser 2 is provided at a refrigerant discharge port of the compressor 21.
2 is connected to a pipe, and an evaporator 24 is connected to the condenser 22 via an expansion valve 23. Further, a refrigerant suction port of the compressor 21 is connected to the evaporator 24 by piping. Compressor 2
A reheater 32 is connected to the first refrigerant discharge port via a flow control valve 31 by piping, and the reheater 32 is connected to the refrigerant inflow side of the expansion valve 23 by piping. Thereby, a second refrigeration cycle is configured.

The evaporators 14, 24 and the reheater 32
Are provided at positions facing each other. The indoor fan 2 sucks indoor air, and blows the sucked air into the room through the evaporators 14, 24 and the reheater 32.

The inverter 3 is a commercial power supply (not shown)
Is rectified, converted to an AC voltage having a frequency corresponding to a command from the control device 4, and output. This output is the compressor 1
1 as driving power.

In the first refrigeration cycle, when the compressor 11 is operated, gaseous refrigerant discharged from the compressor 11 is supplied to the condenser 12 of the outdoor unit 10, and the refrigerant releases heat to the outside air. Liquefy. The refrigerant liquefied in the condenser 12 is supplied to the expansion valve 1
The air is decompressed at 3 and flows to the evaporator 14 of the indoor unit 1, where it takes heat from indoor air to evaporate. The evaporated refrigerant is sucked into the compressor 11.

In the second refrigeration cycle, when the compressor 21 is operated, gaseous refrigerant discharged from the compressor 21 is supplied to the condenser 22 of the outdoor unit 10, and the refrigerant releases heat to the outside air. Liquefy. The refrigerant liquefied in the condenser 22 is supplied to the expansion valve 2.
The air is decompressed at 3 and flows to the evaporator 24 of the indoor unit 1, where it takes heat from indoor air to evaporate. The evaporated refrigerant is sucked into the compressor 21.

When the flow control valve 31 is opened, a part of the refrigerant discharged from the compressor 22 flows into the reheater 32 through the flow control valve 31, and the refrigerant heats the cooling air passing through the evaporators 14 and 24. To liquefy. This heat release raises the temperature of the cooling air. When the opening of the flow control valve 31 changes, the reheater 32
The amount of refrigerant flowing into the cooling air changes, and accordingly, the amount of reheat to the cooling air, the so-called reheat capability, changes. Reheater 3
The refrigerant liquefied in 2 joins the refrigerant flow to the expansion valve 23.

An indoor temperature sensor 5 and an operating device (operating means) 6 are connected to the control device 4. Indoor temperature sensor 5
Detects the air temperature in the room to be conditioned. The operating device 6 is used to set an operation mode and a room temperature.

The control device 4 has the following [1] to [3] as main functional means. [1] The compressor 1 according to an increase in the cooling load (the difference between the temperature detected by the indoor temperature sensor 5 and the indoor set temperature by the operating device 6).
The operation is shifted from the single-unit operation to the two-unit operation of the compressor 11 and the compressor 21, and the compressor 11 and the compressor 2 are operated in accordance with the decrease in the cooling load.
1 to shift from two-unit operation to one-unit operation of compressor 11
Control means.

[2] In the transition from the single-unit operation to the two-unit operation, the reheat amount (reheat capacity) of the reheater 32 is once set to a maximum once the compressor 21 is started, and the reheat amount is reduced from that state. A second control means for reducing the capacity of the compressor 11 (the output frequency of the inverter 3) in accordance with the reduction.

[3] In the transition from the two-unit operation to the one-unit operation, the reheat amount of the reheater 32 is increased, and with this increase, the capacity of the compressor 11 is increased. A third control unit that stops the compressor 21 after the start.

Next, the operation of the above configuration will be described with reference to the flowchart of FIG. The detected temperature of the indoor temperature sensor 5 is compared with the indoor temperature set value by the operation device 6.
If the detected temperature is higher than the set value, and if the operating frequency of the compressor 11 (the output frequency of the inverter 3) has not reached the allowable maximum operating frequency, the compressor according to the difference between the detected temperature and the set value (cooling load). One operation frequency is controlled (one-unit operation).

When the operating frequency of the compressor 11 reaches the maximum allowable operating frequency due to a large cooling load, the compressor 21 is started (two-unit operation). With this activation, the flow control valve 31
Is opened to the maximum opening, and the reheat amount of the reheater 32, that is, the reheat capability is set to the maximum. By setting the reheat capacity to the maximum, it is possible to prevent a sudden increase in the total cooling capacity due to the shift from one-unit operation to two-unit operation.

After the reheat capacity is once set to the maximum, the opening of the flow control valve 31 is reduced, and the reheat capacity is reduced. Although the cooling capacity of the second refrigeration cycle increases due to the reduction of the reheating capacity, the operating frequency of the compressor 11 is reduced with the reduction of the reheating capacity. Due to the decrease in the operating frequency, the total cooling capacity is maintained substantially constant regardless of the increase in the cooling capacity of the second refrigeration cycle.

On the other hand, when the detected temperature becomes equal to or lower than the set value, if the operating frequency of the compressor 11 reaches the allowable minimum operating frequency and the compressor 21 is operating (two-unit operation), Reheat ability is increased.

Although the cooling capacity of the second refrigeration cycle decreases due to the increase in the reheat capacity, the operating frequency of the compressor 11 increases with the increase in the reheat capacity. Due to the increase in the operating frequency, the total cooling capacity is maintained substantially constant irrespective of the decrease in the cooling capacity of the second refrigeration cycle. That is, a rapid decrease in the total cooling capacity due to the shift from the two-unit operation to the one-unit operation is prevented. And
When the reheat capacity becomes maximum, the compressor 21 is stopped (one-unit operation).

Thereafter, in the single-unit operation, if the operating frequency of the compressor 11 has not reached the allowable minimum operating frequency,
The operating frequency is reduced. When the operating frequency reaches the allowable minimum operating frequency, the compressor 11 is stopped (all stops).

As described above, when the compressors 11 and 21 shift from one-unit operation to two-unit operation and when the two-unit operation shifts to one-unit operation, the compression is performed in such a manner as to follow the reheat capability while changing it. Since the operating frequency of the air conditioner 11 is changed so as to avoid a rapid change in the total cooling capacity, it is possible to suppress the room temperature change due to the change in the number of operating units and obtain good temperature controllability.

In addition, as means for suppressing the fluctuation in the indoor temperature due to the change in the number of operating units, the operating frequency is changed while changing the reheating capacity and compensating for the change in the cooling capacity based on the change in the reheating capacity. So
Energy consumption is reduced and energy saving is improved, compared to a conventional system in which room temperature fluctuations are suppressed only by a change in reheat capability.

Since only the compressor 11 of the compressors 11 and 21 is driven by the inverter, the inverter capacity does not increase, and the increase of the negative phase current of the harmonic can be avoided. Satisfactory results can be obtained as a measure against waves.

In the above embodiment, the number of compressors is 2
Although the case where the number of compressors is described as an example, the number of compressors is not limited. In addition, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention.

[0035]

As described above, according to the present invention, when the number of operating first and second compressors changes, the operating frequency of the first compressor is changed while following the reheating capability while changing the reheating capacity. To avoid a sudden change in the total cooling capacity, so that it is possible to obtain good temperature controllability by suppressing room temperature fluctuations due to changes in the number of operating units while ensuring sufficient harmonic countermeasures. It is possible to provide an air conditioner that is capable of performing an optimal operation with sufficient consideration for energy saving.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of one embodiment.

FIG. 2 is a flowchart for explaining the operation of the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 indoor unit 2 indoor fan 3 inverter 4 control device 5 indoor temperature sensor 6 operating device 7 outdoor fan 10 outdoor unit 11 and 21 compressor 12 and 22 condenser 13 and 23 expansion valve 14, 24: evaporator 31: flow control valve 32: reheater

Continuing from the front page (72) Inventor Shigenori Waratani 3-4-1 Shibaura, Minato-ku, Tokyo Inside NTT Facilities Co., Ltd. (72) Kazuo Chiba 3-4-1 Shibaura, Minato-ku, Tokyo Stock (72) Inventor Akira Sasaki 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation F-term (reference) 3L060 AA06 CC00 DD01 DD02 DD03 EE02 EE04

Claims (1)

[Claims] 1. A first refrigeration cycle having a variable capacity first compressor, condenser and evaporator, and a second refrigeration cycle having a fixed capacity second compressor, condenser, evaporator and reheater. In response to an increase in the cooling load, the operation shifts from the operation of one of the first compressors to the operation of the two compressors of the first and second compressors, and the operation of the first and second compressors in response to the decrease in the cooling load. First control means for shifting from two-compressor operation to two-compressor operation to one-compressor operation for the first compressor; and Once set the maximum amount of reheat,
From this state, the amount of reheat is reduced, and a second control means for reducing the capacity of the first compressor in accordance with the reduction is provided. The amount of heat is increased, the capacity of the first compressor is increased with this increase, and the second heat is
An air conditioner, comprising: third control means for stopping the compressor.