JP2002130861A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an air conditioner which will not be short in the cooling capacity of an indoor machine due to the working condition of pipeline connection or the like, and which is high in stability while the degree of freedom in designing the same is increased to contrive the improvement of amenity. SOLUTION: The air conditioner is provided with a plurality of indoor machines 191, 19N having indoor heat exchangers 201, 20N and indoor expansion valves 221, 22N, and an outdoor machine 8. A first outdoor heat exchanger 101 and a first outdoor expansion valve 151 are connected to one pipe branched at one of the discharging side of compressors 91, 92, and a second outdoor heat exchanger 102 as well as a second outdoor expansion valve 12 are connected to the other pipe while an outdoor fan 11 for sending air to the first outdoor heat exchanger 101 and the second outdoor heat exchanger 102 while whose number of rotation is variable. In such an air conditioner, a discharging pressure detector 33 for detecting the discharging pressures of the compressors 91, 92 is provided, and, when a discharging pressure is lowered than a predetermined pressure value upon cooling operation and mainly cooling operation, the number of rotation of the outdoor fan 11 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner in which a plurality of indoor units are connected to an outdoor unit, and more particularly, to a simultaneous cooling and heating operation, that is, a method in which each of the plurality of indoor units is set to be freely cooled and heated. Suitable for driving.

[0002]

2. Description of the Related Art In an air conditioner that performs simultaneous cooling and heating operation using an outdoor unit having two outdoor heat exchangers, the outdoor air temperature is reduced during simultaneous cooling and heating main cooling operation in which one outdoor heat exchanger is a condenser. When the temperature decreases, the amount of refrigerant condensed in the outdoor heat exchanger serving as a condenser increases, and the discharge pressure of the refrigerant decreases. Therefore, the condensing temperature in the heat indoor heat exchanger performing the heat exchange also decreases, and the heating capacity decreases.

Therefore, conventionally, in order to maintain the discharge pressure, the outdoor fan speed is reduced according to the decrease in the outdoor temperature, and the outdoor expansion valve is throttled to increase the liquid refrigerant holding capacity of the outdoor condenser and reduce the heat of condensation. ing.

In addition, the discharge pressure is detected to obtain a predetermined value, and the opening degree of the outdoor expansion valve is controlled by detecting the discharge pressure. When the opening degree of the outdoor expansion valve reaches the upper limit, the outdoor fan speed is increased by a predetermined speed. It is known that the condensing capacity is increased and the condensing capacity is reduced when the lower limit is reached. On the contrary, it is known that the condensing capacity is reduced by decreasing only a predetermined number of revolutions, for example, as described in JP-A-5-99525.

Further, Japanese Patent Application Laid-Open No. 7-4779 describes that the cooling capacity is corrected when the cooling liquid capacity of the cooling operation indoor unit becomes insufficient due to a decrease in the refrigerant liquid pressure in the liquid pipe.

[0006]

In each of the above-mentioned prior arts, the outdoor fan speed is determined in advance by the outdoor air temperature. The outdoor temperature and the rotation speed of the outdoor fan must be matched according to various piping conditions, but if the outdoor fan rotation speed is too low and the refrigerant discharge pressure becomes high, lower the frequency of the compressor, etc. The refrigeration cycle must be protected by emergency control called protection control. Therefore, the outdoor fan speed has to be set high with a margin so that the refrigerant discharge pressure becomes low.

When the outdoor fan speed is set to be high,
For example, at 10 ° C. outside air, the refrigerant discharge pressure becomes low. Therefore, by controlling the refrigerant discharge pressure to a set value by restricting the outdoor expansion valve serving as a condenser, the performance of the heating operation indoor unit is secured, Since the liquid pressure applied to the liquid pipe from the downstream side of the expansion valve decreases and the pressure flowing into the cooling operation indoor unit decreases, the refrigerant may not sufficiently flow into the cooling operation indoor unit, and the cooling capacity may be insufficient.

[0008] The phenomenon that the cooling capacity becomes insufficient is one-unit cooling operation,
In the case of the single-unit heating operation, if the two-unit cooling operation, the one-unit heating operation, and the indoor unit performing the cooling operation are connected to the pipe at the farthest position, the cooling capacity of the cooling-operation indoor unit The shortage is noticeable. For this reason, some restrictions had to be provided for the construction of indoor unit piping.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, so that the cooling capacity of the indoor unit is not insufficient, the stability is high, the degree of freedom in design is increased, and the comfort is improved even under the construction conditions such as pipe connection. The goal is to improve

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a first indoor unit having an indoor heat exchanger and an indoor expansion valve, and a first indoor unit having a branch at the discharge side of the compressor. The outdoor heat exchanger and the first outdoor expansion valve are connected to the other, and the second outdoor heat exchanger and the second outdoor expansion valve are connected to each other, and the number of rotations for blowing air to the first outdoor heat exchanger and the second outdoor heat exchanger is variable. An outdoor unit having an outdoor fan, and an air conditioner including: a discharge pressure detector that detects a discharge pressure of a compressor, and a discharge pressure is lower than a predetermined pressure value during cooling and cooling main operation. In this case, the rotational speed of the outdoor fan is reduced.

In the above-mentioned apparatus, the minimum rotation speed of the outdoor fan is determined in advance, and when the discharge pressure falls below a predetermined pressure value and the outdoor fan reaches the minimum rotation speed,
It is desirable that the opening degree of the first or second outdoor expansion valve connected to the first or second outdoor heat exchanger serving as a condenser is reduced to control the discharge pressure to a predetermined value.
Further, in the above, it is desirable that the rotational speed of the outdoor fan be determined in advance in a plurality of steps.

In the above, when it is determined that the cooling capacity of the indoor unit performing the cooling operation is insufficient during the cooling main operation, the target of the heating capacity of the indoor unit performing the heating operation is determined. It is desirable to lower the value.

Further, in the above, the cooling capacity of the indoor unit performing the cooling operation during the cooling main operation is obtained from the difference between the indoor temperature and the blow-out temperature, and the cooling capacity target obtained from the difference between the set indoor temperature and the indoor temperature. It is desirable to set the target value of the heating capacity of the indoor unit performing the heating operation based on the value.

Further, in the above, a first or second outdoor heat exchanger which becomes an evaporator during a heating main operation,
It is desirable to determine the minimum opening degree of the indoor expansion valve of the indoor unit performing the heating operation based on the capacity ratio of the indoor heat exchanger of the indoor unit performing the cooling operation. Further, a plurality of indoor units having an indoor heat exchanger and an indoor expansion valve, a first outdoor heat exchanger and a first outdoor expansion valve on one side branched off on the discharge side of the compressor, and a second outdoor heat exchange on the other side. And a second outdoor expansion valve connected to the outdoor unit, the first or second outdoor heat exchanger serving as an evaporator during the main heating operation, and the indoor unit performing the cooling operation. The minimum opening degree of the indoor expansion valve of the indoor unit performing the heating operation is determined based on the capacity ratio between the indoor heat exchanger and the indoor heat exchanger.

[0015]

FIG. 2 is a block diagram showing an air conditioner and its control device. The air conditioner comprises an outdoor unit 8, a plurality of cooling / heating switching units 161, 16N, and indoor units 191, 19.
N, an outdoor unit 8 and a plurality of cooling / heating switching units 161 and 16N, and a plurality of cooling / heating switching units 161 and 16N.
6N and indoor units 191 and 19N are connected by piping to form a closed circuit.

The outdoor unit 8 includes a compressor 91 having a variable drive frequency.
92, the first outdoor heat exchanger 101, the second outdoor heat exchanger 10
2 and an outdoor fan 11 that connects the first outdoor expansion valve 151 and the second outdoor expansion valve 152 by piping and sends air to the first outdoor heat exchanger 101 and the second outdoor heat exchanger 102. The simultaneous cooling / heating units 161 and 16N are provided with an electromagnetic valve 1 that connects the high-pressure side gas pipe 47A and the gas side pipe 50B.
71, 17N, low pressure side gas pipe 48A and gas side pipe 4
9B is connected to the electromagnetic valves 181 and 18N.
The indoor heat exchangers 201 and 20N for performing heat exchange with indoor air and the indoor expansion valves 221 and 22N for adjusting the flow rate of the refrigerant in the indoor heat exchangers are sequentially piped. Indoor fan 2 that blows air to 20N
21, 22N.

The outdoor unit 8 includes an accumulator 12, a first four-way valve 131, a second four-way valve 132, and a liquid tank 14. The outdoor unit 8 and each liquid pipe 23 of the cooling / heating switching units 161 and 16N, a high-pressure gas side and a low-pressure Gas side piping 24, 25
Are connected by a liquid pipe 46A, a high-pressure gas side pipe 47A, a low-pressure gas side pipe 48A, and branch pipes 26, 27, 28, respectively.
Cooling / heating switching units 161, 16N and indoor units 191, 1
The liquid side and gas side of 9N are connected by a liquid side pipe 49B and a gas side pipe 50B, respectively, to form a closed circuit, in which a refrigerant is sealed.

Further, an outdoor air temperature detector 29 for detecting outdoor air temperature, a suction pressure detector 32 for detecting refrigerant suction pressure, a discharge pressure detector 33 for detecting refrigerant discharge pressure,
Inverter compressor drive frequency controllers 341 and 342 for controlling the frequencies of the compressors 91 and 92, an outdoor fan blower capacity controller 35 for controlling the blower capacity of the outdoor fan 11,
The first outdoor expansion valve opening operation device 361 for operating the opening degree of the outdoor expansion valve 151, the second outdoor expansion valve opening operation device 362 for operating the opening degree of the second outdoor expansion valve 152, and the first four-way valve 131 First four-way valve operating device 37 for performing an operation of switching the refrigerant direction
1. The second four-way valve operation device 372 for switching the refrigerant direction of the second four-way valve 132, the indoor air temperature detectors 381 and 38N for detecting the indoor air temperature of the use part, and the air temperature blown out to the use part. The blower air temperature detectors 391 and 39N to be detected, and the indoor fan blowing capacity controllers 421 and 42 for controlling the blowing capacity of the indoor fans 211 and 21N.
N, indoor expansion valve opening degree controllers 431 and 43N for controlling the refrigerant circulation amounts of the indoor expansion valves 221 and 22N, for storing a predetermined temperature and humidity set value, or for setting a desired temperature and humidity by a user. Remote control air temperature / humidity setting devices 441, 44
N. Further, the operation value is read by the arithmetic operation device 45, and the operation amount of the operation device is calculated and controlled.

In the air conditioner shown in FIG. 1, in the simultaneous cooling / heating simultaneous cooling main operation, the refrigerant is compressed and superheated by the activation of the compressors 91 and 92, and one of the refrigerant is connected to the first four-way valve 1 via the branch pipe.
The gas flows into the high-pressure side gas pipes 24 and 47A through 31, and flows into the second outdoor heat exchanger 102 through the second four-way valve 132. Cooling operation indoor unit 191 and heating operation indoor unit 19N
In this case, the high-pressure high-temperature refrigerant flowing through the high-pressure side gas pipes 24 and 47A flows into the heating operation cooling / heating unit, flows into the heating operation indoor unit 19N through the solenoid valve 17N, is cooled and liquefied by room air, and is air-cooled. Gives calorie. On the other hand, the refrigerant flowing into the second outdoor heat exchanger 102 is cooled and liquefied by the outdoor air. Next, the liquid pipes 23 and 46A, the cooling operation cooling / heating simultaneous unit 161 and the liquid pipe 49B, further flow into the cooling operation indoor unit 191 and pass through the indoor expansion valve 221 which performs an expansion action. It flows into the heat exchanger 201. Then, it is heated and evaporated by the indoor air, and the heat is taken from the air. The evaporated refrigerant passes through the gas-side pipe 50B and the low-pressure-side gas pipes 48A, 48 through the cooling operation cooling / heating switching unit solenoid valve 181.
And returns to the compressor to repeat the above operation.
The arithmetic operation device 45 controls the refrigerant temperature and pressure of the air conditioner in order to control the indoor air temperature and humidity.

Heating operation In order to secure the heating capacity of the indoor unit, the high pressure side gas pipes 24 and 47A which are in a high pressure and high temperature state are required.
It is necessary to make the refrigerant pressure and temperature in the inside sufficiently high, and the refrigerant pressure and temperature in the high pressure gas side pipes 24 and 47A can be controlled by the refrigerant discharge pressure. Therefore, it is preferable to set the refrigerant discharge pressure to a certain value or more.

In the simultaneous cooling / heating cooling main operation, when the outdoor temperature decreases and the rotation speed of the outdoor fan 11 is higher than an appropriate value, the refrigerant flowing into the other second outdoor heat exchanger 102 is excessively cooled and condensed. Therefore, the amount of liquid refrigerant in the second outdoor heat exchanger is increased by narrowing the second outdoor expansion valve 152, so that the second outdoor heat exchanger 10
By reducing the heat exchange amount of No. 2, the refrigerant discharge pressure can be kept high.

However, in the method in which the outdoor fan speed is determined in advance based on the outdoor temperature, the outdoor fan speed must be set higher, so that the amount of outdoor heat exchange becomes excessive and the second outdoor expansion valve 152 must be throttled. . In this case, the liquid pipes 23, 4 downstream of the second outdoor expansion valve 152
The refrigerant in 6A is decompressed and thus has a low pressure, and the low-pressure liquid refrigerant flows to the cooling operation indoor unit 191.

When the closest indoor unit 571 is a cooling operation indoor unit, the middle room is a heating operation indoor unit 572, and the farthest indoor unit 573 is a cooling operation indoor unit as shown in the example of FIG. Although the refrigerant joins the liquid pipe 58, the liquid refrigerant flowing out of the heating operation indoor unit 572 has a high pressure, and when the liquid pressure of the liquid pipe 58 is low, the liquid refrigerant used in the heating operation indoor unit 572 is: The amount going to the closer cooling operation indoor unit 571 increases, and the amount flowing to the farther cooling operation indoor unit 573 decreases. Therefore, the far cooling operation indoor unit 5
The cooling capacity of the air conditioner 73 is greatly reduced. To prevent this drop, inject the hot gas bypass just before the liquid tank,
There is a method of increasing the pressure of the liquid pipe 58 to reduce the pressure difference between the liquid refrigerant after heating and the liquid refrigerant, but it cannot sufficiently correct the cooling capacity.

Therefore, in this embodiment, the refrigerant discharge pressure is ensured to obtain the heating capacity, and the liquid pipes 23, 46 in FIG.
In order to increase the pressure of A, the number of rotations of the outdoor fan 11 is fed back using the detection value of the refrigerant discharge pressure detector 33 to prevent an excessive number of rotations of the outdoor fan. The outdoor expansion valve opening 152 is operated only in a secondary manner when the condensing capacity of the outdoor fan 11 cannot be reduced below this level, thereby ensuring the refrigerant discharge pressure and increasing the refrigerant pressure of the liquid pipes 23 and 46A. Ensure the cooling operation indoor unit cooling capacity. That is, when the discharge pressure becomes lower than the predetermined pressure value during the cooling and the cooling main operation, the number of revolutions of the outdoor fan 11 is reduced to control the discharge pressure to the predetermined value.

More specifically, an outdoor fan blowing capacity controller 35 is used so that the number of rotations of the outdoor fan 11 can be changed continuously or with sufficient fineness, and the number of outdoor fan steps is 15 or more. Make it change. As shown in FIG. 1, when the discharge pressure detection value is higher than the target pressure by, for example, 0.2 MPa or more (2), it is increased by one step (3), and when it is lower than 0.2 MPa (4), the rotation speed is reduced by one step. (6). Thereby, the refrigerant discharge pressure can be controlled at ± 0.2 MPa, so that the heating capacity can be ensured.

Since the outdoor fan performs feedback control in a stepwise manner based on the detected discharge pressure, the step does not become a carelessly high step. Therefore, it is not necessary to throttle the outdoor expansion valve 152, and the refrigerant pressure in the liquid pipe A is also ensured. The cooling capacity of the cooling operation indoor unit can be secured. However,
Under conditions where the outside air is low, such as when the outdoor temperature is −5 ° C., the discharge pressure cannot be secured even if the outdoor fan 11 is set to the lower limit step (minimum rotation speed). ) Only the second outdoor expansion valve 15
2 is squeezed (7).

As described above, when the outdoor temperature is high, the control by the outdoor fan 11 is performed, and when the discharge pressure cannot be sufficiently maintained only by the control by the outdoor fan 11, the outdoor expansion valve 1 is controlled.
By performing the control by 51 and 152 (outdoor fan-outdoor expansion valve link control), when simultaneous cooling and heating are mainly performed, cooling capacity and heating capacity are secured in accordance with various indoor unit construction conditions and air temperature conditions. I can do it.

In addition to maintaining the liquid pipe pressure by the refrigerant discharge pressure control, control for further correcting the cooling capacity is performed. In other words, when the terminal connection indoor unit is constructed to be extremely distant, the cooling capacity is corrected at the time of simultaneous cooling and heating main cooling operation while slightly sacrificing the heating capacity in order to further correct the cooling capacity. For example, when the pressure of the refrigerant flowing out of the heating operation indoor unit is high, it is difficult for the refrigerant to flow into the terminal connection cooling operation indoor unit, so that the pressure of the refrigerant flowing out of the heating operation indoor unit is reduced.

The cooling capacity of the indoor unit is roughly measured by a temperature difference Δt _(C) between the suction temperature (indoor temperature) and the blowout temperature. As shown in FIG. 4, the cooling operation indoor unit determines a cooling capacity target value Δts _{(C) based} on a difference ΔT _(C) between the set indoor temperature and the indoor temperature. The heating operation indoor unit determines the heating capacity target value Δts _{(H) based} on the difference ΔT _(H) between the indoor temperature and the set indoor temperature. Therefore, when there is an indoor unit having a decreased Δt _(C), it is confirmed that the heating capacity of the heating operation indoor unit has a certain allowable amount.
If the cooling capacity is reduced and the heating capacity is output in an allowable amount, the target value Δts _(H) of the set blowing-suction temperature difference of the heating capacity is changed. By setting the .DELTA.ts upper limit Δtu _(H) the shortfall e of cooling capacity of the _{(H) (C) = Δts} (C) -Δt (C), as the heating capacity setpoint .DELTA.ts _(H) is reduced It is reset. If there are many cooling operation indoor units with insufficient cooling capacity,
Use e _(C) .

Since the heating target capacity is reduced, the expansion valve in the heating operation room has a sufficient output, and the liquid pressure downstream of the expansion valve in the heating operation indoor unit decreases, and the difference between the expansion valve and the liquid refrigerant coming from the liquid pipe is reduced. The pressure decreases, and the refrigerant flows not only to the nearest cooling operation indoor unit but also to the furthest refrigeration operation indoor unit. Then, the cooling capacity of the farthest cooling operation indoor unit also increases.

[0031] The shown in the control flow is 7, the first cooling operation of the indoor unit capacity shortage _{e (C) = Δts (C} ) -Δt (C)
Is measured (64). Next, it is checked whether or not there is a cooling operation unit whose capacity is significantly reduced, and whether or not e _(C) ≧ E is satisfied for e _(C) of each cooling operation indoor unit (65). E is a predetermined constant. If there is a cooling operation indoor unit that is decreasing,
Since the refrigerant is not sufficiently supplied to the cooling operation indoor unit, the capacity needs to be corrected. Therefore, it is confirmed whether the heating blow-out temperature of the heating operation indoor unit is high to some extent (6).
6). Since it is sufficient to check whether the functional capacity of the heating operation room is output, not only the difference between the blowout temperature but also the difference between the temperature difference between the blowout temperature and the suction temperature of the heating operation indoor unit Δt _(H) is determined whether it is larger than a certain constant. Good. If the capacity of the heating operation indoor unit is sufficiently output, the cooling capacity correction is performed. If the capacity of the heating operation indoor unit is not output, the control is continued with the previous heating capacity target value without performing the cooling capacity correction. If it is determined that the cooling capacity correction is possible, select e _(C) of the cooling operation indoor unit with the lowest cooling capacity and calculate the target upper limit value Δtu _(H) of each heating operation indoor unit based on that value. (62, 67). From the calculated target upper limit, the target value Δt _(H) of each heating operation indoor unit is calculated again (63, 6).
8), each heating operation indoor unit controls the indoor expansion valve using the value (69). Through this series of operations, the refrigerant flowing into the heating operation indoor unit is supplied to the cooling operation indoor unit having insufficient cooling capacity, and the insufficient capacity of the cooling operation indoor unit is corrected.

During the simultaneous cooling / heating simultaneous heating operation, the cooling capacity of the terminal connection cooling operation indoor unit similarly decreases. Therefore, the refrigerant flowing into the heating operation indoor unit is adjusted to correct the cooling capacity. The cooling-heating simultaneous heating main operation is different from the cooling main operation, in which the outdoor heat exchanger is an evaporator. For this reason, the cooling capacity is reduced in terms of heat balance. Therefore, for the terminal connection indoor unit to which the liquid refrigerant is hardly supplied, the cooling capacity is significantly reduced.

In the simultaneous cooling / heating simultaneous heating main operation of the air conditioner, when the compressors 91 and 92 are started, the enclosed refrigerant is compressed and superheated, and one of the refrigerants is passed through the first four-way valve 131 through the branch pipe. High-pressure gas pipe 24, 47A
Meanwhile, the other flows to the second outdoor heat exchanger 102 through the second four-way valve 132. However, since the opening degree of the second outdoor expansion valve 152 is almost completely closed, the flow rate of the refrigerant is small. Assuming that the cooling operation indoor unit is 191 and the heating operation indoor unit is 19N, the high-pressure high-temperature refrigerant flowing through the high-pressure side gas pipes 24 and 47A flows into the heating operation cooling / heating unit 16N, and further the electromagnetic valve 1
The air flows into the heating operation indoor unit 19N through 7N, is cooled and liquefied by the indoor air, and gives heat to the air. next,
The liquid refrigerant that has finished heating flows through the liquid pipe 49B, the heating / cooling / heating switching unit 16N, and the liquid pipe 46A, and one of them flows into the cooling / cooling / heating switching unit 161, the liquid pipe 49B, and the cooling operation indoor unit 191. Then, by passing through the indoor expansion valve 221 which performs an expansion action, the pressure is reduced and flows into the cooling operation indoor heat exchanger 201. The refrigerant is heated and evaporated by the indoor air, and takes heat from the air. The evaporated refrigerant flows into the low-pressure side gas pipes 48A and 25 through the gas side pipe 50B and the cooling operation cooling / heating switching unit solenoid valve 181, and returns to the compressor. The other of the liquid refrigerant after the heating is directed to the first outdoor heat exchanger 101, is decompressed by the first outdoor expansion valve 151, and evaporates in the first outdoor heat exchanger 101. The evaporated refrigerant returns to the compressor again, and repeats the above operation.

In the above-described cooling / heating / heating-main operation, one of the liquid refrigerants having finished heating is supplied to the cooling operation indoor unit 191 and the other is supplied to the first cooling refrigerant indoor unit.
It flows to the outdoor heat exchanger 101. When the cooling operation indoor unit is the terminal connection indoor unit, a large amount of the air flows into the first outdoor heat exchanger 101, so that the cooling capacity is significantly reduced. Therefore, the amount of refrigerant flowing into the heating operation indoor unit 19N is increased, and the amount of refrigerant flowing into the cooling operation indoor unit 191 is increased. Specifically, the first outdoor heat exchanger 10 is heat-balanced.
1 and the cooling operation indoor heat exchanger 201 are evaporators, and the heating operation indoor heat exchanger 19N is a condenser. Therefore, the ratio of the capacity of the first outdoor heat exchanger 101 to the capacity of the cooling operation indoor heat exchanger 201 is used. Therefore, the opening degree of the minimum expansion valve of the heating operation indoor unit 19N is limited to a high degree, and the amount of refrigerant flowing into the cooling operation indoor unit 191 is secured. When the capacity ratio of the cooling operation indoor heat exchanger 201 is large, a large amount of refrigerant is required to output the cooling capacity. The minimum expansion valve opening is changed stepwise or continuously according to the capacity ratio between the first outdoor heat exchanger and the cooling operation indoor heat exchanger. When the capacity ratio between the first outdoor heat exchanger and the cooling operation indoor unit is R, for example, by setting the minimum opening EVImin of the indoor expansion valve of the heating operation indoor unit to EVImin = 1000 + 1000R, particularly to the terminal connection indoor unit To ensure a sufficient supply of liquid refrigerant to reduce the cooling capacity.

During simultaneous cooling / heating simultaneous cooling main operation, the outdoor fan 11
And the outdoor expansion valve 152 perform feedback control, thereby reducing the pressure difference between the refrigerant liquid pressure downstream of the heating operation indoor unit and the refrigerant liquid pressure in the liquid pipe, and cooling the furthest cooling operation indoor unit, which tends to be insufficient. The capacity can be secured, and the air conditioning system can be balanced as a whole.

In the simultaneous cooling / heating main operation, the target value of the heating capacity is changed in accordance with the output state of the cooling capacity, so that the refrigerant liquid pressure downstream of the indoor unit of the heating operation and the refrigerant liquid pressure of the liquid pipe are also changed. And corrects the cooling capacity of the farthest cooling operation indoor unit, which tends to be insufficient. During simultaneous heating and cooling main operation, cooling operation is performed by determining the minimum opening degree of the indoor unit expansion valve of the heating operation indoor unit based on the capacity ratio of the first outdoor heat exchanger, which is an evaporator, and the cooling operation indoor heat exchanger. Refrigerant flowing to the indoor unit and refrigerant capacity can be secured.

[0037]

According to the present invention, in an air conditioner that performs simultaneous cooling and heating operations, it is possible to eliminate insufficient capacity and uneven capacity. It is possible to obtain a comfortable air conditioner with high design flexibility.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating pressure control according to one embodiment.

FIG. 2 is a block diagram showing a configuration of an air conditioner according to one embodiment.

FIG. 3 is a block diagram showing a case where a heating operation indoor unit is located in front of a farthest cooling operation indoor unit in simultaneous cooling and heating operation according to an embodiment.

FIG. 4 is a graph showing a relationship between a difference Δt _(C) between an indoor temperature and an outlet temperature and a cooling capacity target value Δts _(C) in the cooling operation indoor unit according to the embodiment.

FIG. 5 is a diagram illustrating an example of the capacity shortage e _(C) of the cooling operation indoor unit and the upper limit value Δtu _(H) of the heating capacity target value Δts _(H) of the heating operation indoor unit in the simultaneous cooling / heating simultaneous cooling main operation according to the embodiment. The graph which shows the relationship.

6 is a graph showing a relationship between the upper limit value Δtu _(H) and a new target capacity value Δts _(H) of the indoor unit for heating operation based on the result of FIG.

FIG. 7 is a flowchart showing control for correcting cooling capacity in simultaneous cooling / heating simultaneous cooling main operation in one embodiment.

[Explanation of symbols]

8 ... outdoor unit, 91 ... compressor, 92 ... compressor, 101 ... first outdoor heat exchanger, 102 ... second outdoor heat exchanger, 11 ... outdoor fan, 151 ... first outdoor expansion valve, 152 ... second Outdoor expansion valve, 161, 16N: cooling / heating switching unit, 191,
19N: indoor unit, 201, 20N: indoor heat exchanger, 21
1, 21N: indoor fan, 221, 22N: indoor expansion valve, 23: liquid pipe, 24: high pressure side gas pipe A, 25 ... low pressure side gas pipe A, 26, 27, 28 ... branch pipe, 32 ... suction pressure detection , 33 ... Discharge pressure detector.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiki Hata 390 Muramatsu, Shimizu-shi, Shizuoka Pref.Hitachi Air Conditioning Systems Shimizu Co., Ltd. (72) Inventor Kenichi Oishi 390 Muramatsu, Shimizu-shi Shizuoka Pref. Within the Production Division (72) Inventor Nobuhiro Sano 390 Muramatsu, Shimizu-shi, Shizuoka Prefecture F-term in Hitachi Air-Conditioning Systems Shimizu Production Division (Reference) 3L060 AA05 CC02 CC16 DD02 EE06 EE09 3L092 GA02 GA09 HA01 JA13 KA02 KA13 LA05 LA08

Claims (7)

[Claims] 1. A plurality of indoor units having an indoor heat exchanger and an indoor expansion valve, a first outdoor heat exchanger and a first outdoor expansion valve on one side branched on the discharge side of the compressor, and a second outdoor heat exchanger on the other side. An outdoor unit having an outdoor fan connected to an outdoor heat exchanger and a second outdoor expansion valve and having a variable-speed outdoor fan for blowing air to the first outdoor heat exchanger and the second outdoor heat exchanger. At
Air, comprising: a discharge pressure detector that detects a discharge pressure of the compressor; wherein, when the discharge pressure falls below a predetermined pressure value during cooling and cooling main operation, the number of revolutions of the outdoor fan is reduced. Harmony machine. 2. The outdoor fan according to claim 1, wherein the outdoor fan has a predetermined minimum rotation speed, and the discharge pressure is lower than a predetermined pressure value, so that the outdoor fan has reached the minimum rotation speed. In this case, the opening degree of the first or second outdoor expansion valve connected to the first or second outdoor heat exchanger serving as a condenser is controlled to be small so that the discharge pressure becomes a predetermined value. An air conditioner characterized by that: 3. The air conditioner according to claim 1, wherein the number of rotations of the outdoor fan is determined in advance in a plurality of steps. 4. The indoor unit performing a heating operation when it is determined that the cooling capacity of the indoor unit performing the cooling operation during cooling main operation is insufficient. An air conditioner characterized by lowering the target value of the heating capacity of the air conditioner. 5. The air conditioner according to claim 1, wherein the cooling capacity of the indoor unit performing the cooling operation during the cooling main operation is obtained from the difference between the indoor temperature and the blowing temperature, and the difference between the set indoor temperature and the indoor temperature is obtained. An air conditioner characterized in that a target value of the heating capacity of an indoor unit performing a heating operation is set based on a target value of a cooling capacity obtained by the following. 6. The apparatus according to claim 1, wherein the first or second outdoor heat exchanger serving as an evaporator during a heating main operation, and the indoor heat exchanger of the indoor unit performing a cooling operation. An air conditioner characterized in that a minimum opening degree of the indoor expansion valve of the indoor unit performing the heating operation is determined according to a capacity ratio of the air conditioner. 7. A plurality of indoor units each having an indoor heat exchanger and an indoor expansion valve, a first outdoor heat exchanger and a first outdoor expansion valve on one side branched off on the discharge side of the compressor, and a second outdoor unit on the other side. An air conditioner comprising an outdoor unit to which an outdoor heat exchanger and a second outdoor expansion valve are connected, wherein the air conditioner performs a cooling operation with the first or second outdoor heat exchanger serving as an evaporator during a heating main operation. An air conditioner, wherein a minimum opening of the indoor expansion valve of the indoor unit that is performing a heating operation is determined based on a capacity ratio between the indoor heat exchanger of the indoor unit and the indoor heat exchanger.