JP6824259B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner configured by connecting a plurality of outdoor units and at least one or more indoor units with a common gas pipe and a common liquid pipe, and the present invention relates to a plurality of outdoor units particularly during cooling operation. Of these, the present invention relates to a method of migrating the refrigerant existing in the closed circuit when one or more outdoor units are stopped.

Conventionally, in order to cope with an increase in the capacity of an air conditioner, there has been an air conditioner in which a plurality of outdoor units and a plurality of indoor units are connected by a common gas pipe and a common liquid pipe. (See, for example, Patent Document 1).

In the air conditioner described in Patent Document 1, an accumulator is often mounted on an outdoor unit to store excess refrigerant. In addition, in general, the amount of refrigerant circulating in each outdoor unit is adjusted by controlling the number of revolutions of the compressor, the number of revolutions of the fan, the opening degree of the flow rate adjusting valve, etc. Often treatment is done. In this way, a simple circuit configuration can be realized without connecting the accumulators mounted on the outdoor units with a liquid leveling pipe or a pressure leveling pipe.

Japanese Unexamined Patent Publication No. 2001-201199

In the air conditioner described in Patent Document 1, since the state in which the refrigerant is accumulated in the closed circuit may be maintained, the refrigerant is removed from the closed circuit so that the pressure in the closed circuit does not exceed the permissible value. Need to move. Then, in order to move the refrigerant from the closed circuit, a bypass pipe connecting the outdoor units is generally provided. However, providing a dedicated bypass pipe in this way has a problem of increasing the product cost.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an air conditioner capable of suppressing a pressure in a closed circuit within an allowable value while suppressing an increase in cost. It is said.

The air conditioner according to the present invention includes an indoor unit, a plurality of outdoor units, a control device, and an indoor unit that constitutes a refrigerant circuit that circulates a refrigerant by connecting a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger. In an air conditioner in which a plurality of the outdoor units are connected in parallel to the indoor unit by a gas pipe and a liquid pipe, the outdoor unit blocks the flow path of the refrigerant and partially blocks the refrigerant circuit. A flow path closing device for closing the circuit, a bypass pipe connected from the downstream side of the outdoor heat exchanger to the low pressure side of the compressor during cooling operation, and a bypass flow rate adjusting valve provided in the bypass pipe. It has an accumulator connected to the low pressure side of the compressor and the bypass pipe, and a pressure sensor for detecting the low pressure side pressure of the outdoor unit. The bypass pipe is connected to the closed circuit and the control The apparatus is a state in which one or more of the plurality of outdoor units is stopped during the cooling operation, the pressure in the closed circuit formed in the stopped outdoor unit, and the outdoor unit during operation. The opening degree of the bypass flow control valve of the outdoor unit that is stopped is determined from the pressure calculation unit that calculates the differential pressure from the low pressure side pressure, and the bypass flow control valve is set to the determined opening degree. Thermal energy calculation to calculate the thermal energy required to evaporate the liquid refrigerant in the accumulator after the opening degree of the bypass flow rate adjusting valve is controlled by the valve opening control unit to be controlled and the valve opening control unit. The inflow gas calorie calculation unit that calculates the calorific value of the inflow gas that flows into the compressor after the opening degree of the bypass flow control valve is controlled by the valve opening control unit, the required heat energy, and the inflow. A time calculation unit that calculates the first time until the liquid refrigerant in the accumulator evaporates using the calorific value of the gas, a determination unit that determines whether or not the first time exceeds the control start time, and the above. When the determination unit determines that the first time exceeds the control start time, it is provided with a compressor control unit that accelerates the compressor according to the value of the first time.

According to the air conditioner according to the present invention, there is a difference between the pressure calculation unit that calculates the differential pressure between the pressure in the closed circuit formed in the outdoor unit that is stopped and the low pressure side pressure of the outdoor unit that is in operation. It is equipped with a valve opening control unit that determines the opening degree of the bypass flow rate adjusting valve from the pressure and controls the bypass flow rate adjusting valve to the determined opening degree, and removes the refrigerant in the closed circuit of the outdoor unit that is stopped. Since it is moved to the low pressure side of the outdoor unit during operation via the bypass pipe connected to the closed circuit, the pressure in the closed circuit can be suppressed within the allowable value even if the pressure in the closed circuit rises. .. Further, since it is not necessary to provide a dedicated bypass pipe, an increase in cost can be suppressed.

It is a refrigerant circuit diagram which shows the refrigerant circuit structure of the air conditioner which concerns on embodiment of this invention. It is a functional block diagram of the control device of the air conditioner which concerns on embodiment of this invention. It is a flowchart which shows the flow of the control process of the air conditioner which concerns on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below. Further, in the drawings below, the relationship between the sizes of the constituent members may differ from the actual one.

Embodiment.
FIG. 1 is a refrigerant circuit diagram showing a refrigerant circuit configuration of the air conditioner 300 according to the embodiment of the present invention.
Hereinafter, the circuit configuration and operation of the air conditioner 300 according to the present embodiment will be described with reference to FIG.
The air conditioner 300 uses a refrigerating cycle (heat pump cycle) for circulating a refrigerant to perform a cooling operation or a heating operation.

The air conditioner 300 is configured by connecting two outdoor units 10a and an outdoor unit 10b and two indoor units 50a and an indoor unit 50b by a refrigerant pipe. The two user units are connected in parallel to the two heat source machines to communicate with each other. That is, the air conditioner 300 forms a refrigerant circuit by connecting each device mounted on the two heat source machines and each device mounted on the two user-side units with a refrigerant pipe, and this refrigerant By circulating the refrigerant in the circuit, it is possible to perform cooling operation or heating operation.

The refrigerant piping of the air conditioner 300 includes a gas branch pipe connected to each outdoor unit, that is, a gas branch pipe 202a connected to the outdoor unit 10a and a gas branch pipe 202b connected to the outdoor unit 10b. The gas branch pipe connected to the indoor unit, that is, the gas branch pipe 206a connected to the indoor unit 50a and the gas branch pipe 206b connected to the indoor unit 50b are connected to the gas branch pipe and the gas branch pipe. A common gas pipe 204, a liquid branch pipe connected to each outdoor unit, that is, a liquid branch pipe 203a connected to the outdoor unit 10a, a liquid branch pipe 203b connected to the outdoor unit 10b, and each indoor unit. The liquid branch pipe connected to, that is, the liquid branch pipe 207a connected to the indoor unit 50a and the liquid branch pipe 207b connected to the indoor unit 50b, and the common liquid branch pipe and the liquid branch pipe are connected to each other. It consists of a liquid pipe 205.

A gas distributor 200 for connecting these refrigerant pipes is provided between the gas branch pipe 202a and the gas branch pipe 202b and the gas pipe 204. Further, a liquid distributor 201 for connecting these refrigerant pipes is provided between the liquid branch pipe 203a and the liquid branch pipe 203b and the liquid pipe 205. Although FIG. 1 illustrates a state in which the gas distributor 200 and the liquid distributor 201 are mounted on the air conditioner 300, the state is limited to the state where the gas distributor 200 and the liquid distributor 201 are mounted. is not it. Further, the gas branch pipe 202a, the gas branch pipe 202b, and the gas pipe 204 form a gas pipe, and the liquid branch pipe 203a, the liquid branch pipe 203b, and the liquid pipe 205 form a liquid pipe.

The outdoor unit 10a and the indoor unit 50a are connected via a gas branch pipe 202a, a gas pipe 204, a gas branch pipe 206a, a liquid branch pipe 207a, a liquid pipe 205, and a liquid branch pipe 203a. Further, the outdoor unit 10a and the indoor unit 50b are connected via a gas branch pipe 202a, a gas pipe 204, a gas branch pipe 206b, a liquid branch pipe 207b, a liquid pipe 205, and a liquid branch pipe 203a.

Similarly, the outdoor unit 10b and the indoor unit 50a are connected via a gas branch pipe 202b, a gas pipe 204, a gas branch pipe 206a, a liquid branch pipe 207a, a liquid pipe 205, and a liquid branch pipe 203b. Further, the outdoor unit 10b and the indoor unit 50b are connected via a gas branch pipe 202b, a gas pipe 204, a gas branch pipe 206b, a liquid branch pipe 207b, a liquid pipe 205, and a liquid branch pipe 203b.

The outdoor unit 10a includes a compressor 1a, an oil separator 2a, a check valve 3a, a four-way valve 4a, an outdoor heat exchanger 5a, a high / low pressure heat exchanger 6a, a flow rate adjusting valve 8a, and a liquid side. An on-off valve 9a, a gas-side on-off valve 11a, an accumulator 12a, an oil return bypass capillary 13a, an oil return bypass solenoid valve 14a, and a bypass flow rate adjusting valve 7a are mounted. Compressor 1a, oil separator 2a, check valve 3a, four-way valve 4a, outdoor heat exchanger 5a, high / low pressure heat exchanger 6a, flow control valve 8a, liquid side on-off valve 9a, gas side on-off valve 11a, and accumulator 12a is provided so as to be connected in series by a refrigerant pipe.

The high / low pressure heat exchanger 6a is provided in the liquid pipe 26a between the outdoor heat exchanger 5a and the flow rate regulating valve 8a. The high / low pressure heat exchanger 6a is branched from the liquid pipe 26a and the liquid pipe 26a between the high / low pressure heat exchanger 6a and the flow rate adjusting valve 8a, and is upstream of the accumulator 12a on the low pressure side of the compressor 1a. The bypass pipe 23a connected to the side is connected. Further, the bypass flow rate adjusting valve 7a is provided in the bypass pipe 23a between the high and low pressure heat exchanger 6a and the flow rate adjusting valve 8a.

Further, the oil return bypass capillary 13a and the oil return bypass solenoid valve 14a are provided in the oil return bypass circuit 29a connecting the oil separator 2a and the refrigerant pipe connecting the accumulator 12a and the compressor 1a. There is. The oil return bypass capillary 13a is provided so as to connect the upstream side and the downstream side of the oil return bypass solenoid valve 14a and bypass the oil return bypass solenoid valve 14a.

In the following description, the point where the liquid pipe 26a and the bypass pipe 23a are connected is referred to as a connection point 25a, and the bypass pipe 23a, the four-way valve 4a, and the upstream pipe between the accumulator 12a are connected. The point is referred to as a connection point 24a.

Further, the outdoor unit 10a is equipped with a control device 27a that controls the drive of each actuator mounted on the outdoor unit 10a, such as a compressor 1a, a four-way valve 4a, and an outdoor blower (not shown). Further, the outdoor unit 10a includes a first pressure sensor 15a, a second pressure sensor 16a, a first temperature sensor 17a, a second temperature sensor 18a, a third temperature sensor 19a, a fourth temperature sensor 20a, and a fifth temperature sensor 21a. A sixth temperature sensor 22a and a seventh temperature sensor 28a are provided.

The compressor 1a has an inverter circuit, and the compressor rotation speed is controlled by power frequency conversion by the inverter circuit to control the capacity. The sucked refrigerant is compressed into a high temperature and high pressure state. It is a thing. The oil separator 2a is provided on the discharge side of the compressor 1a, and has a function of separating the refrigerating machine oil component from the refrigerant gas discharged from the compressor 1a and mixed with the refrigerating machine oil. The check valve 3a is provided in the refrigerant pipe between the oil separator 2a and the four-way valve 4a, and is for preventing the backflow of the refrigerant to the discharge portion side of the compressor 1a when the compressor 1a is stopped. ..

The four-way valve 4a functions as a flow path switching device, and switches the flow of the refrigerant between the cooling operation and the heating operation. However, in the case of a circuit dedicated to cooling, the four-way valve 4a is not required. Further, the flow path switching device may be configured by combining a two-way valve, a three-way valve, or the like instead of the four-way valve 4a.

The outdoor heat exchanger 5a functions as a condenser or radiator during cooling operation and as an evaporator during heating operation, and exchanges heat between air supplied from an outdoor blower (not shown) and a refrigerant. is there. The high / low pressure heat exchanger 6a exchanges heat between the refrigerant flowing through the liquid pipe 26a and the refrigerant flowing through the bypass pipe 23a. The flow rate adjusting valve 8a is installed on the downstream side of the connection point 25a in the cooling circuit, functions as a pressure reducing valve or an expansion valve, and decompresses and expands the refrigerant. The flow rate adjusting valve 8a may be configured such that the opening degree can be variably controlled, for example, an electronic expansion valve or the like.

The liquid side on-off valve 9a conducts or shuts off the refrigerant by opening and closing the control device 27a or manually. The gas side on-off valve 11a also conducts or does not conduct the refrigerant by opening and closing the control device 27a or manually. The liquid-side on-off valve 9a and the gas-side on-off valve 11a are installed to adjust the pressure fluctuation in the refrigeration cycle by opening and closing. The accumulator 12a is provided on the suction side of the compressor 1a and stores excess refrigerant circulating in the refrigerant circuit.

The bypass flow rate adjusting valve 7a is installed in the bypass pipe 23a between the connection point 25a and the high / low pressure heat exchanger 6a, functions as a pressure reducing valve or an expansion valve, and decompresses and expands the refrigerant. The bypass flow rate adjusting valve 7a may be configured such that the opening degree can be variably controlled, for example, an electronic expansion valve. The oil return bypass circuit 29a returns the refrigerating machine oil separated by the oil separator 2a to the suction side of the compressor 1a. The return oil bypass capillary 13a adjusts the flow rate of refrigerating machine oil passing through the return oil bypass circuit 29a. The return oil bypass solenoid valve 14a is controlled to open and close to adjust the flow rate of the refrigerating machine oil together with the return oil bypass capillary 13a.

The first pressure sensor 15a is provided between the oil separator 2a and the four-way valve 4a, and detects the pressure of the refrigerant discharged from the compressor 1a. The second pressure sensor 16a is provided on the upstream side of the accumulator 12a and detects the pressure of the refrigerant sucked into the compressor 1a. The first temperature sensor 17a is provided between the compressor 1a and the oil separator 2a, and detects the temperature of the refrigerant discharged from the compressor 1a. The second temperature sensor 18a detects the ambient temperature of the outdoor unit 10a. The third temperature sensor 19a is provided between the outdoor heat exchanger 5a and the high / low pressure heat exchanger 6a, and detects the temperature of the refrigerant passing between the outdoor heat exchanger 5a and the high / low pressure heat exchanger 6a. Is.

The fourth temperature sensor 20a is provided in the bypass pipe 23a after passing through the high / low pressure heat exchanger 6a, and detects the temperature of the refrigerant passing through the bypass pipe 23a after passing through the high / low pressure heat exchanger 6a. The fifth temperature sensor 21a is provided between the connection point 25a and the flow rate adjusting valve 8a, and detects the temperature of the refrigerant passing through the liquid pipe 26a between the connection point 25a and the flow rate adjusting valve 8a. The sixth temperature sensor 22a is provided between the connection point 24a and the accumulator 12a, and detects the temperature of the refrigerant passing between the connection point 24a and the accumulator 12a. The seventh temperature sensor 28a is provided between the accumulator 12a and the compressor 1a, and detects the temperature of the refrigerant sucked into the compressor 1a.

Then, the pressure information detected by each pressure sensor and the temperature information detected by each temperature sensor are sent to the control device 27a as a signal. The control device 27a controls each actuator based on the signals transmitted from each pressure sensor and each temperature sensor, which will be described in detail later. The type of the control device 27a is not particularly limited, but is, for example, dedicated hardware capable of controlling each actuator mounted on the outdoor unit 10a, a microcomputer for executing a program stored in a memory, or the like. It should be configured.

FIG. 2 is a functional block diagram of the control device 27a of the air conditioner 300 according to the embodiment of the present invention.
As shown in FIG. 2, the control device 27a includes a compressor control unit 30, an outside air temperature acquisition unit 31, a first determination unit 32, a pressure calculation unit 33, a pressure acquisition unit 34, and a valve opening control unit. 35, a thermal energy calculation unit 36, an inflow gas heat quantity calculation unit 37, a time calculation unit 38, and a second determination unit 39 are provided.

By the way, the outdoor unit 10b has the same configuration as the outdoor unit 10a. That is, if "a" of the component component of the outdoor unit 10a is changed to "b", it becomes a component component of the outdoor unit 10b. Further, in the following, when "a" or "b" is not added to the code of the component part of the outdoor unit, it shall be a generic term.

Although FIG. 1 illustrates a state in which a control device is mounted on both the outdoor unit 10a and the outdoor unit 10b, one control device controls both the outdoor unit 10a and the outdoor unit 10b. You may. Further, when the control devices are mounted on both the outdoor unit 10a and the outdoor unit 10b, the control devices can communicate with each other by wire or wirelessly.

An indoor heat exchanger 100a and an expansion valve 101a are mounted on the indoor unit 50a connected in series by a gas branch pipe 206a and a liquid branch pipe 207a. Further, the indoor unit 50a is equipped with a control device 102a that controls the drive of each actuator such as an expansion valve 101a and an indoor blower (not shown), which are mounted on the indoor unit 50a. Further, the indoor unit 50a is provided with an eighth temperature sensor 103a and a ninth temperature sensor 104a.

The indoor heat exchanger 100a functions as an evaporator during cooling operation and as a condenser (or radiator) during heating operation, and exchanges heat between the refrigerant and air. The expansion valve 101a functions as a pressure reducing valve or an expansion valve to reduce the pressure of the refrigerant and expand it. The expansion valve 101a may be configured such that the opening degree can be variably controlled, for example, an electronic expansion valve. The eighth temperature sensor 103a is provided in the gas branch pipe 206a connected to the indoor heat exchanger 100a, and detects the temperature of the refrigerant at the gas side outlet of the indoor heat exchanger 100a. The ninth temperature sensor 104a is provided in the liquid branch pipe 207a connected to the indoor heat exchanger 100a, and detects the temperature of the refrigerant at the liquid side outlet of the indoor heat exchanger 100a.

Then, the temperature information detected by each temperature sensor is sent to the control device 102a as a signal. As will be described in detail later, the control device 102a controls each actuator based on the signal transmitted from each temperature sensor. The type of the control device 102a is not particularly limited, but is, for example, dedicated hardware capable of controlling each actuator mounted on the indoor unit 50a, a microcomputer for executing a program stored in a memory, or the like. It should be configured.

By the way, the indoor unit 50b has the same configuration as the indoor unit 50a. That is, if "a" of the component component of the indoor unit 50a is changed to "b", it becomes a component component of the indoor unit 50b. Further, in the following, when "a" or "b" is not added to the code of the component part of the indoor unit, it shall be a generic term.

Note that FIG. 1 illustrates a state in which a control device is mounted on both the indoor unit 50a and the indoor unit 50b, but one control device controls both the indoor unit 50a and the indoor unit 50b. You may. Further, in a state where the control devices are mounted on both the indoor unit 50a and the indoor unit 50b, the control devices can communicate with each other by wire or wirelessly. Further, the control device mounted on the indoor unit can communicate with the control device mounted on the outdoor unit by wire or wirelessly.

In the cooling circuit of the air conditioner 300, the compressor 1, the oil separator 2, the check valve 3, the four-way valve 4, the outdoor heat exchanger 5, the high and low pressure heat exchanger 6, the flow rate adjusting valve 8, the liquid side on-off valve 9, The expansion valve 101, the indoor heat exchanger 100, the gas side on-off valve 11, the four-way valve 4, and the accumulator 12 are sequentially connected by pipes so that the refrigerant flows.

Next, the operation of the air conditioner 300 according to the present embodiment will be described.
First, the operation of the air conditioner 300 during the cooling operation will be described.
In this case, the four-way valve 4 is switched so that the refrigerant discharged from the compressor 1 flows into the outdoor heat exchanger 5. That is, in the four-way valve 4, the pipes are connected in the solid line direction shown in FIG. Further, the flow rate adjusting valve 8 is set to the fully open state or a state close to the fully open state, the bypass flow rate adjusting valve 7 is set to an appropriate opening degree, the expansion valve 101 is set to an appropriate opening degree, and the operation is started. The flow of the refrigerant in this case is as follows.

The high-temperature, high-pressure gas refrigerant discharged from the compressor 1 first passes through the oil separator 2. At this time, most of the refrigerating machine oil mixed with the refrigerant is separated from the refrigerant, stored in the inner bottom of the oil separator 2, and passes through the oil return bypass circuit 29. If the oil return bypass solenoid valve 14 is open, it also passes through it. It is returned to the suction pipe of the compressor 1. As a result, the refrigerating machine oil flowing out of the outdoor unit 10 can be reduced, and the reliability of the compressor 1 can be improved.

The high-temperature and high-pressure refrigerant with a reduced proportion of refrigerating machine oil passes through the four-way valve 4, is condensed and liquefied by the outdoor heat exchanger 5, and passes through the high- and low-pressure heat exchanger 6. The refrigerant flowing out of the high / low voltage heat exchanger 6 is branched into a refrigerant flowing through the bypass pipe 23 and a refrigerant flowing through the liquid pipe 26. The refrigerant flowing through the bypass pipe 23 is appropriately adjusted in flow rate by the bypass flow rate adjusting valve 7 to become a low-pressure / low-temperature refrigerant, and heat is exchanged with the refrigerant exiting the outdoor heat exchanger 5 in the high-low pressure heat exchanger 6. Therefore, the enthalpy is lower in the refrigerant state on the outlet side of the high / low voltage heat exchanger 6 than in the refrigerant state on the outlet side of the outdoor heat exchanger 5.

The low-pressure refrigerant flowing out of the high-low pressure heat exchanger 6 through the bypass flow rate adjusting valve 7 flows through the bypass pipe 23 and reaches the connection point 24a where the bypass pipe 23a and the upstream pipe of the accumulator 12a are connected. .. As a result, the enthalpy difference increases, so that the required refrigerant flow rate when the same capacity is used can be reduced, and there is an effect of improving performance by reducing pressure loss. The high pressure and low pressure referred to here represent the relative relationship of the pressure in the refrigerant circuit, and the same applies to the temperature.

On the other hand, the high-pressure side refrigerant flowing out of the high-low pressure heat exchanger 6 passes through the flow rate adjusting valve 8, but since the flow rate adjusting valve 8 is in a state of being fully open or nearly fully open, the liquid is used as a high-pressure liquid refrigerant without reducing the pressure. It is supplied to the pipe 205. After that, the liquid refrigerant enters the indoor unit 50, is depressurized by the expansion valve 101 to become a low-pressure two-phase refrigerant, and is evaporated and gasified by the indoor heat exchanger 100. At this time, cooling air is supplied to the air-conditioned space such as a room, and the cooling operation of the air-conditioned space is realized. The refrigerant flowing out of the indoor heat exchanger 100 passes through the gas pipe 204, the four-way valve 4, and the accumulator 12, and is sucked into the compressor 1 again.

Here, since the accumulator 12 is provided with a U-shaped tube as shown in FIG. 1, when the refrigerant in the gas-liquid two-phase state flows into the accumulator 12, the liquid refrigerant collects in the lower part of the container of the accumulator 12. The gas-rich refrigerant flowing in from the upper opening of the U-shaped tube will flow out from the accumulator 12. By providing such an accumulator 12, a gas-rich refrigerant is sucked into the compressor 1. Since the accumulator 12 can store a transient liquid or gas-liquid two-phase refrigerant, it is possible to temporarily prevent the liquid back of the compressor 1 until it overflows, whereby the reliability of the compressor 1 can be prevented. The effect of maintenance is obtained.

FIG. 3 is a flowchart showing a flow of control processing of the air conditioner 300 according to the embodiment of the present invention.
Hereinafter, the flow of the control process executed by the control device 27, which is a feature of the air conditioner 300 according to the present embodiment, will be described in detail with reference to FIG.
First, when the remote control switch of the indoor unit 50 is turned on by the user, the compressor control unit 30 of the control device 27 starts driving the compressor 1 and starts the cooling operation by the air conditioner 300 (step S1). .. At this time, of the plurality of outdoor units, one of the outdoor units, for example, the outdoor unit 10b is in the thermo-OFF state, that is, the compressor 1b is in the stopped state. After turning on the power of the outdoor unit 10 and the indoor unit 50, each control unit constituting the control device 27 sets a fixed value by the initial setting according to the initial state detection of each sensor, and completes the start-up process. It is assumed that

Further, when the compressor 1b of the outdoor unit 10b is stopped while the outdoor unit 10a is in operation, the check valve 3b, the bypass flow rate adjusting valve 7b, and the flow rate adjusting are performed in the refrigerant circuit constituting the outdoor unit 10b. the valve 8b, a closed circuit outflow of refrigerant is blocked not made, respectively, are formed. That is, the check valve 3b, the bypass flow rate adjusting valve 7b, and the flow rate adjusting valve 8b are flow path closing devices that block the flow path of the refrigerant and close a part of the refrigerant circuit.

After step S1, the outside air temperature acquisition unit 31 of the control device 27 determines the outside air temperature immediately after the outdoor unit 10b is stopped, which is detected by the second temperature sensor 18b, or after the refrigerant transfer control shown below is previously executed. Acquire the information of Tb (step S2).

After step S2, the outside air temperature acquisition unit 31 of the control device 27 acquires the information of the outside air temperature Tbn after a lapse of a certain time from the detection of the outside air temperature Tb detected by the second temperature sensor 18b (step S3). ). The first determination unit 32 of the control device 27 predicts the degree of pressure rise in the closed circuit of the stopped outdoor unit 10b based on the difference temperature between the outside air temperature Tbn and the outside air temperature Tb. Then, it is determined that the pressure of the piping in the closed circuit of the stopped outdoor unit 10b exceeds the allowable pressure depending on whether or not the difference temperature exceeds a certain threshold value ΔT. Therefore, the first determination unit 32 of the control device 27 determines Tbn−Tb ≧ ΔT (≧ 0 ° C.) (step S4).

When the condition of Tbn−Tb ≧ ΔT is satisfied (Yes in step S4), the first determination unit 32 of the control device 27 determines that the pressure in the closed circuit of the stopped outdoor unit 10b exceeds the allowable pressure. Then move on to the next step.
On the other hand, when the condition of Tbn−Tb ≧ ΔT is not satisfied (No in step S4), the first determination unit 32 of the control device 27 is in the closed circuit of the outdoor unit 10b which is stopped until the condition is satisfied. Tbn−Tb ≧ ΔT is determined at regular intervals until it is determined that the pressure exceeds the allowable pressure (step S4).

After step S4, the pressure calculation unit 33 of the control device 27 calculates the pressure Pm in the closed circuit of the outdoor unit 10b stopped from the outside air temperature Tbn.

Here, the degree of increase in the actual pressure Pm in the closed circuit depends on the filling rate of the liquid refrigerant existing in the closed circuit of the outdoor unit 10b that is stopped (= the volume of the refrigerant in the closed circuit / the volume in the closed circuit piping). Change. Therefore, in the pressure calculation unit 33 of the control device 27, foreign matter is temporarily caught in the bypass flow rate adjusting valve 7b and the flow rate adjusting valve 8b of the outdoor unit 10b that is stopped, and the liquid refrigerant fills the closed circuit with a filling rate of 1 = 1. Assuming the case of, the pressure Pm in the closed circuit is calculated from the outside air temperature Tbn (step S5). Further, the pressure in the accumulator on the operating side to which the refrigerant is transferred ≈ the pressure detected by the second pressure sensor 16a is set as the low pressure pressure Ps on the operating side, and the pressure acquisition unit 34 of the control device 27 detects it by the second pressure sensor 16a. Information on the pressure applied is acquired (step S6). Then, the pressure calculation unit 33 of the control device 27 calculates the differential pressure ΔP = Pm−Ps (step S7).

After step S7, the valve opening control unit 35 of the control device 27 determines the opening degree of the bypass flow rate adjusting valve 7b according to the differential pressure ΔP calculated in step S7, and determines the bypass flow rate adjusting valve 7b. The opening degree is controlled (step S8), and the appropriate amount of refrigerant is transferred. The flow of the refrigerant at this time is the flow indicated by the arrow in the refrigerant circuit diagram shown in FIG. 1. First, the refrigerant existing in the closed circuit of the outdoor unit 10b opens the bypass flow rate adjusting valve 7b. After passing through the high-low pressure heat exchanger 6b, the gas moves to the low-pressure four-way valve 4b side via the bypass pipe 23b, and flows into the outdoor unit 10a in the order of the gas branch pipe 202b and the gas branch pipe 202a. Finally, it is assumed that the excess refrigerant flows into the accumulator 12a for storing the surplus refrigerant. By shifting the appropriate amount of refrigerant in this way, even if the pressure in the closed circuit of the stopped outdoor unit 10b rises, the pressure in the closed circuit of the stopped outdoor unit 10b can be suppressed within the allowable value. Can be done.

After the refrigerant is transferred to the accumulator 12a, the excess refrigerant in the accumulator 12a is transferred to the refrigerant again in the next control due to the amount of the refrigerant distributed in the accumulator 12a and the latent heat of the refrigerant and the amount of low-pressure gas heat flowing into the accumulator 12a. You need to decide if you can.

Next, the amount of refrigerant distributed in the accumulator 12a will be described. During the cooling operation, the outlet states of the outdoor unit 10a and the outdoor unit 10b are controlled to keep the degree of superheat constant by using the eighth temperature sensor 103 and the ninth temperature sensor 104. Further, the outlet state of the bypass pipe 23a after passing through the high / low voltage heat exchanger 6a is controlled to keep the degree of superheat constant by using the fourth temperature sensor 20a and the second pressure sensor 16a.

Therefore, the liquid refrigerant does not flow into the accumulator 12a, and only the amount of movement of the refrigerant in step S8 is used as the amount of refrigerant distributed in the accumulator 12a. The amount of movement of the refrigerant is calculated using the fifth temperature sensor 21b (determination of liquid density), the differential pressure ΔP = Pm-Ps, and the opening degree of the bypass flow rate adjusting valve 7b. The amount of movement of the refrigerant is set so as to be equal to or less than the effective volume of the accumulator 12a of the outdoor unit 10a on the operating side to which the refrigerant is moved. That is, the valve opening degree control unit 35 determines the opening degree of the bypass flow rate adjusting valve 7 from the effective volume of the accumulator 12 of the outdoor unit 10 during operation in addition to the differential pressure ΔP.

Further, the saturation temperature of the accumulator 12a is calculated using the pressure detected by the second pressure sensor 16a. Further, the saturated liquid enthalpy and the saturated gas enthalpy are calculated using the pressure detected by the second pressure sensor 16a, and the latent heat amount of the refrigerant is calculated from the saturated liquid enthalpy and the saturated gas enthalpy.

Then, the thermal energy required to evaporate the liquid refrigerant in the accumulator 12a is calculated from the refrigerant distribution amount and the latent heat amount of the refrigerant in the accumulator 12a.

The enthalpy of the gas refrigerant flowing into the accumulator 12a during the cooling operation is calculated using the temperature detected by the sixth temperature sensor 22b and the pressure detected by the second pressure sensor 16a. Further, the amount of refrigerant circulating in the accumulator 12a is determined by the operating state of the compressor 1a (operating frequency, pressure detected by the first pressure sensor 15a, pressure detected by the second pressure sensor 16a, and the seventh temperature sensor 28b. It is calculated from the detected temperature). Then, the calorific value of the inflow gas flowing into the accumulator 12a is calculated from the enthalpy of the gas refrigerant flowing into the accumulator 12a during the cooling operation and the circulation amount of the refrigerant flowing into the accumulator 12a.

As described above, the thermal energy calculation unit 36 of the control device 27 calculates the thermal energy required to evaporate the liquid refrigerant in the accumulator 12a from the refrigerant distribution amount and the latent heat amount of the refrigerant in the accumulator 12a (step S9). Further, the inflow gas heat amount calculation unit 37 of the control device 27 calculates the heat amount of the inflow gas flowing into the accumulator 12a from the enthalpy of the gas refrigerant flowing into the accumulator 12a and the circulation amount of the refrigerant flowing into the accumulator 12a during the cooling operation. (Step S10). Then, the time calculation unit 38 of the control device 27 calculates the time t_ac until the liquid refrigerant in the accumulator 12a evaporates by using the required heat energy and the amount of heat of the inflow gas (step S11).

After step S11, the second determination unit 39 of the control device 27 determines whether the time t_ac until the liquid refrigerant evaporates exceeds the control start time ts2 after the next step S2 (t_ac> ts2) (step S12). ).
When the second determination unit 39 of the control device 27 determines that the condition of t_ac> ts2 is satisfied (Yes in step S12), the compressor control unit 30 of the control device 27 determines that the compressor frequency F of the compressor 1a. By increasing the speed according to t_ac (step S13), the amount of heat of the inflow gas flowing into the accumulator 12a is increased, and t_ac is shortened. Then, the control device 27 repeats step S12 and step S13 until the condition of t_ac> ts2 is no longer satisfied. By doing so, the surplus refrigerant in the accumulator 12a is surely evaporated, and then the resumption of control after step S2 is permitted (step S12).
On the other hand, when the second determination unit 39 of the control device 27 determines that the condition of t_ac> ts2 is not satisfied (No in step S12), the second determination unit 39 returns to step S2 again.
In addition, in step S12, it is corrected that the accumulator 12a overflows and the liquid refrigerant is sucked into the compressor 1a.

From the above, the air conditioner 300 according to the present embodiment is an indoor unit 50 that constitutes a refrigerant circuit that circulates a refrigerant by connecting a compressor 1, an outdoor heat exchanger 5, an expansion valve 101, and an indoor heat exchanger 100. In an air conditioner 300 including a plurality of outdoor units 10 and a control device 27, and a plurality of outdoor units 10 are connected in parallel to the indoor unit 50 by gas pipes and liquid pipes, the outdoor unit 10 is a refrigerant. A flow path closing device that closes the flow path of the refrigerant circuit to close a part of the refrigerant circuit, and a bypass pipe 23 connected from the downstream side of the outdoor heat exchanger 5 to the low pressure side of the compressor 1 during cooling operation. The bypass pipe 23 has a bypass flow control valve 7 provided in the bypass pipe 23 and a pressure sensor for detecting the pressure, the bypass pipe 23 is connected to a closed circuit, and a plurality of control devices 27 are used during the cooling operation. Calculate the difference pressure between the pressure in the closed circuit formed in the stopped outdoor unit 10 and the low pressure side pressure of the operating outdoor unit 10 when one or more of the outdoor units 10 are stopped. The pressure calculation unit 33 is provided, and the valve opening degree control unit 35 that determines the opening degree of the bypass flow rate adjusting valve 7 from the differential pressure and controls the bypass flow rate adjusting valve 7 to the determined opening degree.

According to the air conditioner 300 according to the present embodiment, the pressure in the closed circuit can be suppressed within an allowable value even when the pressure in the closed circuit rises. Further, since it is not necessary to provide a dedicated bypass pipe, an increase in cost can be suppressed.

Further, the air conditioner 300 according to the present embodiment includes a temperature sensor that detects the outside air temperature, and the pressure calculation unit 33 applies the pressure in the closed circuit formed in the stopped outdoor unit 10 to the outdoor unit. It is calculated from the outside air temperature after a certain period of time has elapsed since 10 was stopped.

Conventionally, by directly detecting the pressure in the closed circuit with a pressure sensor or the like so that the pressure in the closed circuit does not exceed the permissible value, the refrigerant is moved through the bypass pipe or the like, and the pressure in the closed circuit is used. There is something to adjust. Further, there is a device in which the pressure in the closed circuit is similarly adjusted by providing a pressure relief port or the like that is opened in parallel with the closed circuit when the pressure exceeds a predetermined primary side.

The pressure calculation unit 33 calculates the pressure in the closed circuit formed in the stopped outdoor unit 10 from the outside air temperature after a certain period of time has elapsed since the outdoor unit 10 was stopped. Therefore, it is not necessary to provide a means for directly detecting the pressure such as a pressure sensor, or a pressure relief port or the like that opens when the pressure exceeds a predetermined primary side in parallel with the closed circuit. The increase can be suppressed.

Further, in the air conditioner 300 according to the present embodiment, the outdoor unit 10 has an accumulator 12 connected to the low pressure side of the compressor 1 and the bypass pipe 23, and the valve opening degree control unit 35 has a differential pressure. In addition, the opening degree of the bypass flow rate adjusting valve 7 is determined from the effective volume of the accumulator 12 of the outdoor unit 10 during operation.

Conventionally, when an accumulator is mounted on an outdoor unit, the flow rate of the refrigerant is controlled by a liquid level detector provided on the accumulator. However, considering the cost, productivity, and reliability of the liquid level detector, it is more realistic to increase the capacity of the accumulator sufficiently so that the refrigerant does not overflow. However, if an attempt is made to prepare for overflow by increasing the capacity of the accumulator, it will not be possible to meet the demand for compactness and cost reduction.

According to the air conditioner 300 according to the present embodiment, the opening degree of the bypass flow rate adjusting valve 7 is determined from the effective volume of the accumulator 12 of the outdoor unit 10 in operation in addition to the differential pressure. Therefore, it is possible to prepare for overflow without increasing the capacity of the accumulator 12, and it is possible to meet the demand for compactness and cost reduction.

Further, in the air conditioner 300 according to the present embodiment, the control device 27 allows the refrigerant in the closed circuit of the outdoor unit 10 that is stopped to be passed through the bypass pipe 23 connected to the closed circuit to the outdoor unit during operation. The time calculation unit 38 that calculates the time until the refrigerant in the accumulator 12 evaporates after moving to the low pressure side of the machine 10 and the refrigerant in the closed circuit of the outdoor unit 10 that is stopped based on the time are combined. It is provided with a determination unit for determining the timing of moving the outdoor unit 10 in operation to the low voltage side again via the bypass pipe 23 connected to the closed circuit.

Conventionally, in an air conditioner in which two or more outdoor units are combined, the outdoor units to be restarted are determined at a certain cycle in order to equalize the operating load of each outdoor unit. However, if a certain period of time does not elapse, the outdoor unit to be started will not be replaced, and the excess refrigerant will be started in a state of being excessively distributed in the accumulator. If the excess refrigerant treatment after restart cannot be properly controlled, repeated overflows will increase the load on the compressor, that is, the outdoor unit, which may affect the product life and significantly impair quality. There is.

According to the air conditioner 300 according to the present embodiment, the control device 27 transfers the refrigerant in the closed circuit of the stopped outdoor unit 10 to the outdoor during operation via the bypass pipe 23 connected to the closed circuit. The time calculation unit 38 that calculates the time until the refrigerant in the accumulator 12 evaporates after moving to the low pressure side of the machine 10 and the refrigerant in the closed circuit of the outdoor unit 10 that is stopped based on the time are combined. It is provided with a determination unit for determining the timing of moving the outdoor unit 10 in operation to the low voltage side again via the bypass pipe 23 connected to the closed circuit. Therefore, the treatment of excess refrigerant after restart can be appropriately controlled, and overflow can be suppressed. Further, it is possible to suppress an increase in the load on the compressor 1, that is, the outdoor unit 10, and to prevent quality from being impaired.

1 Compressor, 1a Compressor, 1b Compressor, 2 Oil Separator, 2a Oil Separator, 3 Check Valve, 3a Check Valve, 3b Check Valve, 4 Four-way Valve, 4a Four-Way Valve, 4b Four-Way Valve, 5 Outdoor Heat Exchanger, 5a outdoor heat exchanger, 6 high / low pressure heat exchanger, 6a high / low pressure heat exchanger, 6b high / low pressure heat exchanger, 7 bypass flow control valve, 7a bypass flow control valve, 7b bypass flow control valve, 8 flow rate. Control valve, 8a flow control valve, 8b flow control valve, 9 liquid side on-off valve, 9a liquid side on-off valve, 10 outdoor unit, 10a outdoor unit, 10b outdoor unit, 11 gas side on-off valve, 11a gas side on-off valve, 12 Accumulator, 12a Accumulator, 13a Oil return bypass capillary, 14 Return oil bypass electromagnetic valve, 14a Return oil bypass electromagnetic valve, 15a 1st pressure sensor, 16a 2nd pressure sensor, 17a 1st temperature sensor, 18a 2nd temperature sensor , 18b 2nd temperature sensor, 19a 3rd temperature sensor, 20a 4th temperature sensor, 21a 5th temperature sensor, 21b 5th temperature sensor, 22a 6th temperature sensor, 22b 6th temperature sensor, 23 bypass piping, 23a bypass piping , 23b bypass pipe, 24a connection point, 25a connection point, 26 liquid pipe, 26a liquid pipe, 27 control device, 27a control device, 28a 7th temperature sensor, 28b 7th temperature sensor, 29 oil return bypass circuit, 29a return oil Bypass circuit, 30 Compressor control unit, 31 Outside air temperature acquisition unit, 32 First judgment unit, 33 Pressure calculation unit, 34 Pressure acquisition unit, 35 Valve opening control unit, 36 Thermal energy calculation unit, 37 Inflow gas heat quantity calculation unit , 38 hours calculation unit, 39 second judgment unit, 50 indoor unit, 50a indoor unit, 50b indoor unit, 100 indoor heat exchanger, 100a indoor heat exchanger, 101 expansion valve, 101a expansion valve, 102a control device, 103rd 8 temperature sensor, 103a 8th temperature sensor, 104 9th temperature sensor, 104a 9th temperature sensor, 200 gas distributor, 201 liquid distributor, 202a gas branch pipe, 202b gas branch pipe, 203a liquid branch pipe, 203b liquid branch Pipe, 204 gas pipe, 205 liquid pipe, 206a gas branch pipe, 206b gas branch pipe, 207a liquid branch pipe, 207b liquid branch pipe, 300 air conditioner.

Claims (3)

An indoor unit and a plurality of outdoor units that form a refrigerant circuit that circulates a refrigerant by connecting a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger.
Equipped with a control device,
In an air conditioner in which a plurality of the outdoor units are connected in parallel to the indoor unit by gas pipes and liquid pipes.
The outdoor unit is
A flow path blocking device that blocks the flow path of the refrigerant and closes a part of the refrigerant circuit.
Bypass piping connected from the downstream side of the outdoor heat exchanger to the low pressure side of the compressor during cooling operation,
Bypass flow rate adjusting valve provided in the bypass pipe and
With the accumulator connected to the low pressure side of the compressor and the bypass pipe,
It has a pressure sensor that detects the low pressure side pressure of the outdoor unit.
The bypass pipe is connected to the closed circuit and
The control device is
In a state where one or more of the plurality of outdoor units are stopped during the cooling operation.
A pressure calculation unit that calculates the difference pressure between the pressure in the closed circuit formed in the outdoor unit that is stopped and the low pressure side pressure of the outdoor unit that is in operation.
The opening degree of the bypass flow rate adjusting valve of the outdoor unit that is stopped is determined from the differential pressure.
A valve opening control unit that controls the bypass flow rate adjusting valve to a determined opening, and a valve opening control unit.
A thermal energy calculation unit that calculates the thermal energy required to evaporate the liquid refrigerant in the accumulator after the opening degree of the bypass flow rate adjusting valve is controlled by the valve opening control unit.
An inflow gas heat amount calculation unit that calculates the heat amount of the inflow gas flowing into the accumulator after the opening degree of the bypass flow rate adjusting valve is controlled by the valve opening degree control unit.
A time calculation unit that calculates the first time until the liquid refrigerant in the accumulator evaporates using the required heat energy and the amount of heat of the inflow gas.
A determination unit that determines whether or not the first time exceeds the control start time,
An air conditioner including a compressor control unit that accelerates the compressor according to the value of the first time when the determination unit determines that the first time exceeds the control start time. .. The control device is
When it is determined that the first time does not exceed the control start time,
In a state where one or more of the plurality of outdoor units are stopped during the cooling operation.
Again, the differential pressure between the pressure in the closed circuit formed in the stopped outdoor unit and the low pressure side pressure of the outdoor unit during operation is calculated, and the differential pressure is used to calculate the differential pressure of the outdoor unit that is stopped. The air conditioner according to claim 1, wherein the opening degree of the bypass flow rate adjusting valve is determined and the bypass flow rate adjusting valve is controlled to the determined opening degree. Equipped with a temperature sensor that detects the outside air temperature
The pressure calculation unit
The air according to claim 1 or 2, wherein the pressure in the closed circuit formed in the outdoor unit that is stopped is calculated from the outside air temperature after a certain period of time has elapsed since the outdoor unit was stopped. Harmonizer.

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