JP2000314566A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an air conditioner equipped with a two-stage compressor to always perform efficient operation with necessary capability. SOLUTION: An air conditioner is provided with a control means (20) for switching between single-stage compression and two-stage compression, based on the ambient air temperature (T) and a load (Q). In particular, during heating operation, it performs two-stage compression, when the ambient air temperature (T) is lower than a predetermined standard temperature (Ta), while when the ambient air temperature (T) is higher than the predetermined temperature (Ta), it performs single-stage compression, if the load (Q) is smaller than a standard load (Qa) that is previously determined for the ambient air temperature, and performs the two-stage compression if the load (Q) is not smaller than the standard load (Qa).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a two-stage compression mechanism, and more particularly to a technique for controlling switching between a single-stage compression operation and a two-stage compression operation.

[0002]

2. Description of the Related Art Conventionally, an air conditioner which requires low evaporation pressure and high compression ratio operation is disclosed in, for example,
As shown in Japanese Patent No. 80545, a two-stage compression refrigeration cycle is employed. The compression mechanism of the two-stage compression refrigeration cycle includes a first compressor and a second compressor, a single-stage compression operation using only one compressor, and a two-stage compression operation using both compressors in series. It is configured to be able to switch between the compression operation and the compression operation.

In the air conditioner described in the above publication,
As shown in FIG. 7, during the heating operation, the single-stage compression operation is performed when the blow-out temperature is lower than a certain temperature B and the outside air temperature is higher than a certain temperature A, and 2 in other temperature conditions.
Stage compression operation is performed. This is because, when the blowing temperature is higher than B, the energy efficiency of the two-stage compression operation is higher than that of the single-stage compression operation, and when the outside air temperature is higher than a certain temperature A, the single-stage compression operation is higher than the two-stage compression operation. This is because the energy efficiency is high. In the cooling operation, the single-stage compression operation is always performed because the energy efficiency is high even if the compression ratio is not set high.

[0004]

However, in such operation control, for example, when the heating operation is started, the blow-out temperature is low, so that when the outside air temperature is higher than A, the single-stage compression operation is performed. In other words, at the time of start-up, it is desired to drive with a high capacity, but on the other hand, the operation is performed with a low capacity. In addition, when the outside air temperature is high, even if the room temperature rises, if the blowing temperature is high, the two-stage compression operation is performed, so that the operation is wasted. Further, in the case of the cooling operation, since the single-stage compression operation is always performed, sufficient performance cannot be obtained at the time of startup or the like.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide an air conditioner having a two-stage compression mechanism, which always has an efficient operation with a necessary capacity. Is to be able to do

[0006]

According to a first aspect of the present invention, there is provided an air conditioner having a two-stage compression mechanism (1), based on an outside air temperature (T) and a load (Q). And a control means (20) for switching between a single-stage compression operation and a two-stage compression operation.

[0007] A second solution taken by the present invention is:
In the first solution, the control means (20) performs the two-stage compression operation when the outside air temperature (T) is lower than a predetermined reference temperature (Ta) during the heating operation, while controlling the outside air temperature (T ) Is equal to or higher than the reference temperature (Ta), when the load (Q) is smaller than a predetermined reference load (Qa) with respect to the outside air temperature at that time, a single-stage compression operation is performed, and the load (Q) is When the load is equal to or more than the reference load (Qa), the two-stage compression operation is performed.

[0008] A third solution taken by the present invention is:
In the second solution, the heating reference load (Qa) is
It is set to a larger value as the outside air temperature (T) increases.

A fourth solution taken by the present invention is:
In the first or second solving means, the control means (20)
During the cooling operation, if the outside air temperature (T) is lower than a predetermined reference temperature (Tb), the single-stage compression operation is performed, while the outside air temperature
If (T) is equal to or higher than the reference temperature (Tb), a two-stage compression operation is performed when the load (Q) is higher than a predetermined reference load (Qb) with respect to the outside air temperature at that time. ) Is less than the reference load (Qb), a single-stage compression operation is performed.

[0010] A fifth solution taken by the present invention is:
In the fourth solution, the reference load (Qb) for cooling is
It is set to a smaller value as the outside air temperature (T) increases.

In the first solution, unlike the conventional air conditioner, not the outside air temperature and the blowout temperature but the outside air temperature (T) and the load.
(Q) The single-stage and two-stage compression operations are switched based on (the difference between the room temperature and the set temperature).

For this reason, during the heating operation, when the outside air temperature (T) is lower than the reference temperature (Ta) as in the second solution, the high-capacity operation is performed in the two-stage compression operation, while the outside air is operated. temperature
If (T) is equal to or higher than the reference temperature (Ta), the load (Q)
When it is smaller than (Qa), the operation can be efficiently performed by single-stage compression, and when the load (Q) is equal to or more than the reference load (Qa), high-capacity operation can be performed by two-stage compression.

Further, in the third solution, the outside air temperature
As the (T) becomes higher, the two-stage compression is not performed unless the load (Q), that is, the difference between the room temperature and the set temperature, is large. Otherwise, the single-stage compression can be operated more efficiently. That is, useless driving can be prevented. On the contrary, when the load (Q) is large even when the outside air temperature (T) is high, a high-capacity operation by two-stage compression can be performed.

[0014] In the fourth solution, during cooling operation,
When the outside air temperature (T) is lower than the reference temperature (Tb), high-efficiency operation is performed by single-stage compression.On the other hand, when the outside air temperature (T) is higher than the reference temperature (Tb), the load (Q) is When the load is larger than (Qb), high-capacity operation can be performed by two-stage compression, and when the load (Q) is equal to or less than the reference load (Qb), operation can be efficiently performed by single-stage compression.

[0015] In the fifth solution, the outside air temperature
When (T) is high, high-capacity two-stage compression operation is performed even if the load (Q) is relatively small.

[0016]

According to the first solution, the outside air temperature
The operation of the single-stage compression and the operation of the two-stage compression are switched as necessary from (T) and the load (Q), so that efficient operation can always be performed with the required capacity.

Further, according to the second and third means, the operation can be performed while balancing the performance and efficiency during the heating operation. According to the fourth and fifth means,
During the cooling operation, the operation can be performed while balancing the performance and efficiency. In particular, according to the third and fifth solving means, it is possible to perform an efficient operation without waste without performing the two-stage compression operation more than necessary.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a refrigerant circuit diagram of the air conditioner of the present embodiment. This refrigerant circuit is a two-stage compression mechanism
(1), four-way switching valve (2), indoor heat exchanger (3),
Electronic expansion valve (4), gas-liquid separator (5), second electronic expansion valve
(6) and an outdoor heat exchanger (7),
(1) The first compressor (8) on the lower stage and the second compressor on the upper stage
(9).

Specifically, the discharge side of the first compressor (8) is connected to the suction side of the second compressor (9) via an accumulator (10), and the discharge side of the second compressor (9) is , Four-way switching valve (2),
Indoor heat exchanger (3), first electronic expansion valve (4), gas-liquid separator (5)
, A second electronic expansion valve (6), an outdoor heat exchanger (7), and a four-way switching valve (2), which are connected to the suction side of the first compressor (9). The discharge side of the first compressor (8) is also connected to the four-way switching valve (2) in parallel with the first compressor (9), and the solenoid valve (12) is used to use one of the parallel circuits. , 13) are provided.

The refrigerant circuit according to the present embodiment is configured not only to perform two-stage compression operation, but also to perform gas injection as required. For this reason, gas-liquid separator
Between the gas outlet of (5) and the suction side of the second compressor (9),
An injection passage (14) for sending the gas refrigerant in the gas-liquid separator (5) to the second compressor (9) at the time of the two-stage compression operation is connected, and an electromagnetic valve (15) is connected to the injection passage (14). Is provided. Further, between the indoor heat exchanger (3) and the first expansion valve (4), and between the indoor heat exchanger (3) and the solenoid valve (15) of the injection passage (14).
A part of the refrigerant is injected between the
The (14) is connected to a liquid refrigerant introduction passage (16), and the liquid refrigerant introduction passage (16) is provided with a third electronic expansion valve (17).

The indoor heat exchanger (3) and the outdoor heat exchanger
(7) are air heat exchangers, which are provided in the indoor unit and the outdoor unit, respectively. The indoor unit is provided with an indoor fan (not shown) for supplying air to the indoor heat exchanger (3), and the outdoor unit is provided with an outdoor fan (not shown) for supplying air to the outdoor heat exchanger (7). Z)
Is provided.

FIG. 2 is a block diagram showing a schematic device configuration of the air conditioner. As shown in the figure, an input unit (20) of a controller (20), which is a control unit of the air conditioner,
a) includes the remote control unit (21) and sensor
(22) is connected. The remote control unit (21) is configured to transmit signals such as power on / off and temperature setting to the input unit (20a). Also,
The sensor (22) includes a temperature sensor that detects the outside air temperature and the indoor temperature, a pressure sensor that detects the refrigerant pressure, and the like, and transmits each detected value to the input unit. Note that the outside air temperature and the like may be detected from, for example, the refrigerant pressure.

These input signals are sent to an equipment control section (20c) via an arithmetic section (20b), and the compression mechanism (1) (first compressor (8), 2 compressors (9)
), Fan (23) (indoor fan, outdoor fan), valve
(24) (Four-way switching valve (2), each electronic expansion valve (4, 6, 15), solenoid valve
The operation of each device such as (12, 13, 15)) is controlled.

This air conditioner is configured to switch between the single-stage compression operation and the two-stage compression operation based on the outside air temperature (T) and the load (Q) in both the heating operation and the cooling operation. ing. Here, the load (Q) is the difference between the room temperature and the set temperature.

Specifically, in the case of the heating operation, as shown in FIG. 3, the outside air temperature (T) is set to a predetermined reference temperature (Ta).
If it is lower than this, always perform two-stage compression operation,
If (T) is equal to or higher than the reference temperature (Ta), a single-stage compression operation is performed when the load (Q) is smaller than a predetermined reference load (Qa) according to the outside air temperature (T) at that time, When the load (Q) is equal to or larger than the reference load (Qa), the two-stage compression operation is performed. In this embodiment, the reference load (Q
a) is set to a value that increases linearly as the outside air temperature (T) increases. In other words, as the outside air temperature (T) rises above the reference temperature (Ta) during heating operation, the load
The fact that (Q) is large (in other words, the set temperature is high and the difference from room temperature is large) is a condition for performing the two-stage compression operation.

In the cooling operation, as shown in FIG. 4, when the outside air temperature (T) is lower than a predetermined reference temperature (Tb), the single-stage compression operation is always performed, while the outside air temperature (T ) Is equal to or higher than the reference temperature (Tb), when the load (Q) is higher than a predetermined reference load (Qb) with respect to the outside air temperature (T) at that time, a two-stage compression operation is performed, and the load (Q) Q) is the reference load
(Qb) If it is less than or equal to, the single-stage compression operation is performed. In this embodiment, even if the outside air temperature (T) rises above the reference temperature (Ta), the single-stage compression operation is performed if the load (Q) is small.

-Operation- Next, the operation of the air conditioner will be described.

In this air conditioner, the heating operation or the cooling operation can be arbitrarily selected by switching the four-way switching valve (2). In the heating operation, the four-way switching valve (2) is used.
Is set on the solid line side in the figure, and is set on the broken line side in the cooling operation. When performing two-stage compression operation, the solenoid valve (12) is opened and the solenoid valve (13) is closed, and both compressors (8, 9) are used in series. When performing the operation, use the solenoid valve (1
2) is closed, the solenoid valve (13) is opened, and only the first compressor (8) is used. Further, when performing the gas injection operation during the two-stage compression operation, the injection passage (1
The solenoid valve (15) of 4) is opened.

Hereinafter, as a typical example of the operating state of the air conditioner, a state in which the injection passage (14) is opened by two-stage compression to perform the heating operation will be described. At this time, the controller (20) operates the four-way switching valve (2) and each solenoid valve (12, 13, 1).
In addition to controlling 5), the degree of opening of each electronic expansion valve (4, 6, 17) is adjusted, the refrigerant pressure in the gas-liquid separator (5) is set to a predetermined intermediate pressure, and the compression mechanism is adjusted. In (1), the refrigerant pressure on the discharge side and the suction side is controlled to predetermined high and low pressures.

In this state, the gas refrigerant compressed in two stages in the compression mechanism (1) passes through the four-way switching valve (2) and then flows into the indoor heat exchanger (3). In the indoor heat exchanger (3), the high-temperature and high-pressure gas refrigerant exchanges heat with indoor air to condense and heat the indoor air. The condensed liquid refrigerant is supplied to the first electronic expansion valve.
When passing through (4), the pressure is reduced and a part expands to become a gas-liquid two-phase refrigerant of intermediate pressure. The gas-liquid two-phase refrigerant flows into the gas-liquid separator (5) and is separated into a gas refrigerant and a liquid refrigerant. After flowing out of the gas-liquid separator (5), the liquid refrigerant passes through the second electronic expansion valve (6), becomes a low-pressure two-phase refrigerant, and flows into the outdoor heat exchanger (7). Then, in the outdoor heat exchanger (7), the two-phase refrigerant exchanges heat with the outdoor air to evaporate, and the evaporated gas refrigerant passes through the four-way switching valve (2) and then passes through the accumulator (11). It is sucked into one compressor (1).

On the other hand, the gas refrigerant in the gas-liquid separator (5) is sucked into the second compressor (9) from the injection passage (14) via the solenoid valve (15). At that time, a part of the liquid refrigerant after passing through the indoor heat exchanger (3) is sucked into the liquid refrigerant introduction passage (16), and after being depressurized through the third electronic expansion valve (17), the injection passage ( 14) mixed with the gas refrigerant and evaporated
It is sucked into the compressor (9). By this gas injection operation, the circulation amount of the gas refrigerant flowing through the indoor heat exchanger (3) increases, and the heating capacity improves.

A detailed description of the refrigerant circulation operation will be omitted for the two-stage compression operation performed by closing the injection passage (14), the single-stage compression operation, or the cooling operation performed in a cycle opposite to the heating operation.

Next, the switching operation between the two-stage compression operation and the single-stage compression operation will be described.

FIG. 5 is a flowchart showing the operation of the air-conditioning apparatus of this embodiment during the heating operation. In this flowchart, when the heating operation is started, first, in step ST1, it is determined whether or not the outside air temperature (T) is equal to or higher than the reference temperature (Ta). If the outside air temperature (T) is lower than the reference temperature (Ta), the process proceeds to step ST2, where a two-stage compression operation is performed. At this time, the necessity of the gas injection operation is also selected as necessary (not shown).

In step ST3, it is detected whether or not a stop signal has been input by a remote control unit or the like. If there is no input, the process returns to step ST1, and if there has been input, the operation is stopped.

If it is detected in step ST1 that the outside air temperature (T) is equal to or higher than (Ta), the operation proceeds to step ST4, where the load is reduced.
It is determined whether (Q) is equal to or more than the reference load (Qa). When the load (Q) is equal to or larger than the reference load (Qa), the two-stage compression operation in step ST2 is performed. Conversely, when it is determined that the load (Q) is smaller than the reference load (Qa), the process proceeds to step ST5, where the one-stage compression operation is performed, and the operation after step ST3 is continuously performed.

In this air conditioner, the outside air temperature, the indoor temperature, the set temperature, and the like are constantly detected by the controller.
When the determination result changes according to the temperature change, the two-stage compression operation and the single-stage compression operation are automatically switched.

On the other hand, the flowchart of FIG. 6 shows the operation during the cooling operation. In this flow, first step
In ST11, it is determined whether or not the outside air temperature (T) is equal to or higher than the reference temperature (Tb). If the temperature (T) is low, the process proceeds to step ST12 to perform single-stage compression operation. In step ST13, the presence or absence of a stop signal is detected. If there is no input, the process returns to step ST11, and if there is an input, the operation is stopped.

As a result of the determination in step ST11, the outside air temperature
When detecting that (T) is equal to or more than (Tb), step ST1
Proceed to 4 to determine the load (Q). If the load (Q) is equal to or smaller than the reference load (Qb), the single-stage compression operation in step ST12 is performed. If the load (Q) is larger than the reference load (Qb), the process proceeds to step ST15 to perform the two-stage compression operation and repeats the operation after step ST13. Even during the cooling operation, the switching between the single-stage compression operation and the two-stage compression operation is automatically performed according to changes in the outside air temperature, the indoor temperature, the set temperature, and the like.

According to the present embodiment, during the heating operation, when the outside air temperature (T) is lower than the reference temperature (Ta), the high-capacity operation is always performed in the two-stage compression operation. When the outside air temperature (T) is equal to or higher than the reference temperature (Ta), when the load (Q) is smaller than the reference load (Qa), the operation is efficiently performed by single-stage compression, and the load (Q) is equal to the reference load (Qa). With the above, high-capacity operation can be performed by two-stage compression. During cooling operation, the outside air temperature (T) is equal to the reference temperature (Tb).
If it is lower than this, high efficiency operation is always performed with single-stage compression,
When the outside air temperature (T) is equal to or higher than the reference temperature (Tb), when the load (Q) is higher than the reference load (Qb), high-capacity operation is performed by two-stage compression, and the load (Q) is changed to the reference load (Qb). ) When it is less than or equal to, the operation can be efficiently performed by single-stage compression.

As described above, in this embodiment, the outside air temperature
Since the operation is switched between single-stage compression and two-stage compression as required based on (T) and load (Q), efficient operation can always be performed with the required capacity. That is, it is possible to perform the operation in which the capacity and the efficiency are balanced at the time of heating and at the time of cooling.

[0043]

Other Embodiments of the Invention The present invention may be configured as follows with respect to the above embodiment.

For example, in the above embodiment, the reference load (Qa,
Although Qb) is a value that changes linearly according to the outside air temperature (T), it does not necessarily need to be a value that changes linearly, and a value appropriately determined according to the situation may be used.

The configuration of the refrigerant circuit is merely an example, and is not limited to the above embodiment. For example, a gas injection mechanism is not necessarily provided, and a specific circuit configuration for switching the operation of the compression mechanism (1) between a single stage and a two stage may be appropriately changed. Further, the cooling operation may always be performed by single-stage compression, and the heating operation may be performed while switching between single-stage compression and two-stage compression.

Although the air conditioner capable of switching between the heating operation and the cooling operation has been described in the above embodiment, the single-stage compression operation and the two-stage compression operation can be switched even for a heating-only device or a cooling-only device. Can be configured.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a control block diagram of the air conditioner of FIG.

FIG. 3 is a diagram showing operation mode switching of a compression mechanism during a heating operation in the air-conditioning apparatus of FIG. 1;

FIG. 4 is a diagram showing operation mode switching of a compression mechanism during a cooling operation in the air-conditioning apparatus of FIG. 1;

FIG. 5 is a flowchart showing a heating operation operation of the air-conditioning apparatus of FIG.

FIG. 6 is a flowchart showing a cooling operation of the air-conditioning apparatus of FIG. 1;

FIG. 7 is a diagram showing operation mode switching during a heating operation of a conventional air conditioner.

[Explanation of symbols]

 (1) Compression mechanism (2) Four-way switching valve (3) Indoor heat exchanger (4) First electronic expansion valve (5) Gas-liquid separator (6) Second electronic expansion valve (7) Outdoor heat exchanger ( 8) First compressor (9) Second compressor (10,11) Accumulator (12,13) Solenoid valve (14) Injection passage (15) Solenoid valve (16) Liquid refrigerant introduction passage (17) Third electronic expansion Valve (20) Controller (control means) (21) Remote control unit (22) Sensor (23) Fan (24) Valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshikazu Sato 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries Sakai Works Kanaoka Plant

Claims (5)

[Claims] An air conditioner provided with a two-stage compression mechanism (1), wherein a control for switching between a single-stage compression operation and a two-stage compression operation based on an outside air temperature (T) and a load (Q). An air conditioner comprising means (20). 2. The control means (20) controls an outside air temperature during a heating operation.
When (T) is lower than a predetermined reference temperature (Ta), the two-stage compression operation is performed.On the other hand, when the outside air temperature (T) is higher than the reference temperature (Ta), the load (Q) increases with respect to the outside air temperature. When it is smaller than the predetermined reference load (Qa), perform single-stage compression operation,
The air conditioner according to claim 1, wherein the two-stage compression operation is performed when the load (Q) is equal to or larger than the reference load (Qa). 3. The air conditioner according to claim 2, wherein the heating reference load (Qa) is set to a larger value as the outside air temperature (T) increases. 4. The control means (20) controls the outside air temperature during a cooling operation.
When (T) is lower than a predetermined reference temperature (Tb), single-stage compression operation is performed.On the other hand, when the outside air temperature (T) is higher than the reference temperature (Tb), the load (Q) is When it is larger than the predetermined reference load (Qb), two-stage compression operation is performed,
3. The air conditioner according to claim 1, wherein a single-stage compression operation is performed when the load (Q) is equal to or less than the reference load (Qb). 5. The air conditioner according to claim 4, wherein the cooling reference load (Qb) is set to a smaller value as the outside air temperature (T) increases.