WO2019058464A1

WO2019058464A1 - Air conditioner

Info

Publication number: WO2019058464A1
Application number: PCT/JP2017/033930
Authority: WO
Inventors: 和久岩▲崎▼
Original assignee: 三菱電機株式会社
Priority date: 2017-09-20
Filing date: 2017-09-20
Publication date: 2019-03-28
Also published as: JPWO2019058464A1; DE112017008064T5; JP6785980B2

Abstract

An air conditioner comprises: bypass piping that branches from between an outdoor heat exchanger and an expansion valve in a refrigerant circuit and is connected to the intake side of a compressor; a bypass flow rate regulating valve that is provided in the bypass piping; a supercooling heat exchanger that exchanges heat between refrigerant between the outdoor heat exchanger and the expansion valve and refrigerant downstream of the bypass flow rate regulating valve in the bypass piping; cooling piping that is constituted by a portion of the piping between the outdoor heat exchanger and the supercooling heat exchanger and that cools a control device by the control device being disposed so to be in contact with same; and a temperature regulating valve that is provided between the outdoor heat exchanger and the cooling piping and that regulates the temperature of the refrigerant passing through the cooling piping. The control device controls the temperature regulating valve so that the temperature of a heat dissipation unit of the control device is less than a preset reference value during cooling operation and controls the bypass flow rate regulating valve so that the degree of supercooling at the outlet of the supercooling heat exchanger exceeds a preset value.

Description

Air conditioner

The present invention relates to an air conditioner configured to cool a heat generating portion with a refrigerant of a refrigerant circuit.

The air conditioner includes a refrigerant circuit in which a compressor, a condenser, an expansion valve, and an evaporator are connected by piping. Then, conventionally, for example, a heat generating portion of a control device such as an inverter circuit for controlling a compressor is cooled using a refrigerant flowing in a refrigerant circuit (see, for example, Patent Document 1). In patent document 1, the cooling circuit which branches the refrigerant | coolant of the upstream of an expansion valve, and is connected to the discharge side of a compressor is provided separately from a refrigerant circuit, and the heat generation part is cooled with the refrigerant | coolant which flows through a cooling circuit.

JP, 2015-21659, A

By the way, conventionally, a supercooling heat exchanger is provided between the condenser and the expansion valve, and the refrigerant on the high pressure side of the subcooling heat exchanger is heat exchanged with the refrigerant on the low pressure side of the supercooling heat exchanger to There is an air conditioner that improves the refrigeration efficiency by cooling. It is conceivable to apply the technology of Patent Document 1 to such an air conditioning apparatus to cool the heat generating portion of the control device.

However, in Patent Document 1, it is necessary to provide a dedicated cooling circuit to cool the heat generating portion, which leads to an increase in the size of the product and a complication of the refrigerant circuit. Therefore, it is desirable to cool the heat generating portion with the refrigerant flowing through the refrigerant circuit without providing a dedicated cooling circuit for cooling the heat generating portion.

In order to cool the heat generating portion with the refrigerant flowing through the refrigerant circuit, it is conceivable to use a low temperature refrigerant on the low pressure side of the refrigerant circuit. However, in this method, since the heat generating part is cooled to a temperature equal to or lower than the dew point temperature of air and dew condensation may occur inside the control device, using the high pressure side refrigerant between the condenser and the subcooling heat exchanger good.

When a high pressure side refrigerant is used to cool the heat generating portion, the pipe between the condenser and the subcooling heat exchanger is used as a cooling pipe for cooling the heat generating portion, and an electronic expansion valve is provided upstream of the cooling pipe. The temperature of the refrigerant passing through the cooling pipe is adjusted by the electronic expansion valve to cool the heat generating portion. In this configuration, when the temperature of the heat generating portion rises excessively, the opening degree of the electronic expansion valve is narrowed relatively large to lower the temperature of the refrigerant passing through the cooling pipe. However, if the degree of opening of the electronic expansion valve is narrowed too much, the pressure on the downstream side of the electronic expansion valve decreases, and the degree of supercooling at the outlet of the subcooling heat exchanger located downstream of the electronic expansion valve during cooling operation There is a problem that it can not be secured, and the cooling capacity is reduced. In addition, when the degree of subcooling can not be secured at the outlet of the subcooling heat exchanger, the refrigerant flowing into the expansion valve located on the downstream side of the subcooling heat exchanger is in a gas-liquid two-phase state, and refrigerant flow noise occurs in the expansion valve. There was a problem to occur.

The present invention has been made to solve the problems as described above, and in an air conditioner configured to cool a control device using a refrigerant, the control device can be cooled without causing complication of a refrigerant circuit. Another object of the present invention is to provide an air conditioner capable of suppressing the reduction in capacity during cooling operation and the generation of refrigerant flow noise.

The air conditioner according to the present invention includes a refrigerant circuit in which a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected by piping to circulate a refrigerant, and a control device that controls the refrigerant circuit. A bypass pipe branched from between the outdoor heat exchanger and the expansion valve and connected to the suction side of the compressor, a bypass flow control valve provided in the bypass pipe, and between the outdoor heat exchanger and the expansion valve Of the refrigerant and the refrigerant downstream of the bypass flow control valve of the bypass piping, and the control device contacts among the piping between the outdoor heat exchanger and the subcooling heat exchanger, The cooling device includes a cooling pipe which is disposed to cool the control device, and a temperature control valve which is provided between the outdoor heat exchanger and the cooling pipe and which adjusts the temperature of the refrigerant passing through the cooling pipe. At the same time, the temperature of the heat generating part of the control device is set in advance Less than the controls the thermostatic valve so as, in which the degree of subcooling at the outlet of the subcooling heat exchanger to control the bypass flow rate adjustment valve to exceed a pre-set value.

According to the present invention, it is possible to suppress the reduction in capacity during cooling operation and the generation of refrigerant flow noise without complicating the configuration of the refrigerant circuit.

It is a refrigerant circuit figure showing the refrigerant circuit composition of the air harmony device concerning Embodiment 1 of the present invention. It is a flowchart which shows the flow of the control processing at the time of the air_conditioning | cooling operation in the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the flow of the control processing at the time of heating operation in the air conditioning apparatus which concerns on Embodiment 2 of this invention.

Hereinafter, an air conditioner according to an embodiment of the present invention will be described with reference to the drawings. Here, in the following drawings including FIG. 1, those given the same reference numerals are the same or correspond to this, and are common to the whole text of the embodiments described below. And the form of the component expressed to the whole specification is only an illustration, and is not limited to the form described in the specification. Further, the height and the height of the temperature and the pressure are not particularly determined in relation to the absolute value, but are relatively determined in the state and operation of the air conditioner.

Embodiment 1
FIG. 1 is a refrigerant circuit diagram showing a refrigerant circuit configuration of the air-conditioning apparatus according to Embodiment 1 of the present invention. The circuit configuration and operation of the air conditioner will be described based on FIG. This air conditioning apparatus performs a cooling operation or a heating operation using a refrigeration cycle in which a refrigerant is circulated. In FIG. 1, solid arrows indicate the refrigerant circuit in the cooling operation, and broken arrows indicate the refrigerant circuit in the heating operation. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

As shown in FIG. 1, the air conditioning apparatus is configured by connecting an outdoor unit 10, which is a heat source unit, and an indoor unit 50a and an indoor unit 50b, which are use side units, by refrigerant pipes. The indoor unit 50 a and the indoor unit 50 b are connected in parallel to the outdoor unit 10. That is, the air conditioning apparatus forms a refrigerant circuit by connecting each device mounted on the outdoor unit 10 and each device mounted on each of the indoor unit 50a and the indoor unit 50b with a refrigerant pipe. . Here, a configuration in which two outdoor units 10 are connected to one outdoor unit 10 is shown, but the number of indoor units may be one or more. Also, the number of outdoor units 10 is not limited to one, and may be more than one.

The refrigerant piping of the air conditioner includes gas piping and liquid piping. The gas piping includes a gas piping 204 connected to the outdoor unit 10, and a gas branch pipe 206a and a gas branch pipe 206b connected to each indoor unit. The gas branch pipe 206a is connected to the indoor unit 50a, and the gas branch pipe 206b is connected to the indoor unit 50b. The liquid piping includes a liquid piping 205 connected to the outdoor unit 10, and a liquid branch pipe 207a and a liquid branch pipe 207b connected to each indoor unit. The liquid branch pipe 207a is connected to the indoor unit 50a, and the liquid branch pipe 207b is connected to the indoor unit 50b.

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

[Outdoor unit]
The outdoor unit 10 includes a compressor 1, a four-way valve 4, an outdoor heat exchanger 5, a liquid side on-off valve 9, a gas side on-off valve 11, and an accumulator 12.

The compressor 1 compresses the sucked refrigerant to a high temperature and high pressure state. The compressor 1 has an inverter circuit, and is a compressor of a type in which the compressor rotational speed is controlled by the power supply frequency conversion by the inverter circuit and the capacity is controlled.

The four-way valve 4 functions as a flow path switching device, and switches the flow of the refrigerant between the cooling operation and the heating operation. The outdoor heat exchanger 5 functions as a condenser or a radiator at the time of cooling operation, functions as an evaporator at the time of heating operation, and performs heat exchange between the air supplied from the outdoor fan not shown and the refrigerant. is there.

The liquid side on-off valve 9 is opened or closed automatically by the control device 27 or manually by the user, and does not conduct the refrigerant. Similarly, the gas side on-off valve 11 is opened or closed automatically by the control device 27 or manually by the user, and the refrigerant is not conducted. The liquid side on-off valve 9 and the gas side on-off valve 11 are installed to adjust the pressure fluctuation in the refrigeration cycle by opening and closing.

The accumulator 12 is provided on the suction side of the compressor 1 and stores excess refrigerant circulating in the refrigerant circuit.

The outdoor unit 10 further branches from the liquid pipe 26 between the outdoor heat exchanger 5 and the liquid side on-off valve 9 and is connected to the suction side of the compressor 1, specifically to the inlet side of the accumulator 12. And a bypass flow control valve 7 provided in the bypass pipe 23. The bypass flow rate adjusting valve 7 functions as a pressure reducing valve or an expansion valve to decompress and expand the refrigerant. The bypass flow rate adjusting valve 7 may be configured by one whose opening degree can be variably controlled, for example, an electronic expansion valve or the like. Further, the outdoor unit 10 exchanges heat between the high pressure side refrigerant between the outdoor heat exchanger 5 and the liquid side open / close valve 9 and the low pressure side refrigerant decompressed by the bypass flow rate adjustment valve 7 of the bypass pipe 23 A subcooling heat exchanger 6 is provided to cool the refrigerant.

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

The outdoor unit 10 further includes an oil separator 2, an oil return bypass circuit 30, and a check valve 3. The oil separator 2 is provided on the discharge side of the compressor 1 and has a function of separating a refrigerator oil component from a refrigerant gas discharged from the compressor 1 and mixed with a refrigerator oil.

The oil return bypass circuit 30 is for returning the refrigerator oil separated by the oil separator 2 to the suction side of the compressor 1. The piping of the oil return bypass circuit 30 is connected to a circuit in which the oil return bypass capillary 13 and the oil return bypass solenoid valve 14 are connected in parallel, so that the flow rate of the refrigerator oil returned to the compressor 1 is adjusted. It has become. Specifically, when the oil return bypass solenoid valve 14 is open, refrigeration oil separated by the oil separator 2 is returned to the suction side of the compressor 1 as it is through the oil return bypass solenoid valve 14. On the other hand, when the oil return bypass solenoid valve 14 is closed, the refrigeration oil separated by the oil separator 2 passes through the oil return bypass capillary 13 to reduce the flow rate and is returned to the suction side of the compressor 1.

The check valve 3 is provided in the refrigerant pipe between the oil separator 2 and the four-way valve 4 and prevents the backflow of the refrigerant from the four-way valve 4 side to the discharge side of the compressor 1 when the compressor 1 is stopped. It is for.

In addition, the outdoor unit 10 is configured to cool the heat generating portion of the control device 27 described later with a refrigerant that passes through a pipe that connects the outdoor heat exchanger 5 and the subcooling heat exchanger 6. Among the pipes connecting the outdoor heat exchanger 5 and the subcooling heat exchanger 6, a pipe which is disposed in contact with the control device 27 to cool the heat generating portion is hereinafter referred to as a cooling pipe 40. A temperature control valve 8 is provided between the outdoor heat exchanger 5 and the cooling pipe 40 to adjust the temperature of the refrigerant passing through the cooling pipe 40. The temperature control valve 8 functions as a pressure reducing valve or an expansion valve to decompress and expand the refrigerant. The temperature control valve 8 may be configured by one whose opening degree can be variably controlled, for example, an electronic expansion valve or the like.

Further, the outdoor unit 10 is mounted with a control device 27 that controls the drive of each actuator mounted on the outdoor unit 10. The control device 27 controls each actuator based on signals transmitted from each pressure sensor and each temperature sensor, which will be described in detail later. The actuators correspond to, for example, the compressor 1, the four-way valve 4, and an outdoor fan (not shown). The control device 27 is not particularly limited in type, but may be constituted by a microcomputer or the like capable of controlling each actuator mounted on the outdoor unit 10, for example.

The control device 27 includes an inverter circuit for driving the motor of the compressor 1, and the power module of the inverter circuit generates heat when the compressor 1 is driven and becomes high temperature. In the first embodiment, as described above, the heat generating portion such as the power module is cooled by the refrigerant of the refrigerant circuit.

[Sensor of outdoor unit]
The outdoor unit 10 is provided with a plurality of pressure sensors and a plurality of temperature sensors. Specifically, the outdoor unit 10 is provided with a first pressure sensor 15, a first temperature sensor 18, a second temperature sensor 19, a third temperature sensor 20, and a fourth temperature sensor 21.

The first pressure sensor 15 is provided between the oil separator 2 and the four-way valve 4 and measures the pressure of the refrigerant discharged from the compressor 1.

The first temperature sensor 18 is provided in the heat generating portion of the control device 27 and measures the temperature of the heat generating portion. The second temperature sensor 19 is provided between the connection point 25 and the liquid side on-off valve 9 and measures the temperature of the refrigerant passing through the liquid pipe 26 between the connection point 25 and the liquid side on-off valve 9 . The third temperature sensor 20 measures the temperature of the outside air around the outdoor unit 10. The fourth temperature sensor 21 is provided between the cooling pipe 40 and the subcooling heat exchanger 6 and measures the temperature of the refrigerant passing between the cooling pipe 40 and the subcooling heat exchanger 6. The third temperature sensor 20 corresponds to the outside air temperature sensor of the present invention, and the fourth temperature sensor 21 corresponds to the cooling refrigerant temperature sensor of the present invention.

And the pressure information measured by each pressure sensor and the temperature information measured by each temperature sensor are sent to the control device 27 as a signal. In addition, although the sensor used by the following control was demonstrated here, the sensor is provided in addition to the outdoor unit 10, and it is used for various control in an air conditioning apparatus.

[Indoor unit]
The indoor heat exchanger 100a and the expansion valve 101a are mounted in series on the indoor unit 50a by a gas branch pipe 206a and a liquid branch pipe 207a. In addition, a control device 102a that controls the drive of each actuator mounted on the indoor unit 50a is mounted on the indoor unit 50a. The actuator corresponds to, for example, the expansion valve 101a and an indoor fan (not shown). Furthermore, the indoor unit 50a is provided with a fifth temperature sensor 103a for measuring the temperature of the refrigerant at the liquid side outlet of the indoor heat exchanger 100a in the liquid branch pipe 207a connected to the indoor heat exchanger 100a. .

The indoor heat exchanger 100a functions as an evaporator during the cooling operation and as a condenser or a radiator during the heating operation, and performs heat exchange between the refrigerant and the air. The expansion valve 101a functions as a pressure reducing valve or an expansion valve to decompress and expand the refrigerant. The expansion valve 101a may be configured by one whose opening degree can be variably controlled, for example, an electronic expansion valve or the like.

The temperature information measured by the fifth temperature sensor 103a is sent to the control device 102a as a signal. In addition, although the sensor used by the following control was demonstrated here, the indoor unit is additionally provided with a sensor, and the control apparatus 102a controls each actuator based on the signal transmitted from each temperature sensor It is supposed to The type of the control device 102a is not particularly limited. For example, the control device 102a may be configured by a microcomputer or the like that can control each actuator mounted on the indoor unit 50a.

The indoor unit 50b has the same configuration as the indoor unit 50a. That is, if "a" of the component of the indoor unit 50a is changed to "b", it becomes a component of the indoor unit 50b. In the following, when the indoor unit 50a and the indoor unit 50b are not distinguished from each other, they are referred to as an indoor unit 50. Moreover, when not distinguishing the component in each of the indoor unit 50a and the indoor unit 50b, "a" and "b" may not be provided, but it may be set as the expansion valve 101 generically, for example, if it is an expansion valve. .

Although FIG. 1 shows an example in which the control unit is mounted on both the indoor unit 50a and the indoor unit 50b, one control unit may control both the indoor unit 50a and the indoor unit 50b. You may Moreover, in the state in which the control device is mounted in both the indoor unit 50a and the indoor unit 50b, the control devices of each other can communicate in a wired or wireless manner. Furthermore, the control device mounted in the indoor unit can communicate with the control device mounted in the outdoor unit 10 in a wired or wireless manner.

By the way, conventionally, when cooling the control device with the refrigerant circulating in the refrigerant circuit, it has been necessary to provide a dedicated circuit for cooling the control device. This entails the complication of the refrigerant circuit and the increase in the cost of the product. On the other hand, in the first embodiment shown in FIG. 1, the heat generating portion of the control device 27 is brought into contact with the cooling pipe 40 which is a part of the pipe connecting the temperature control valve 8 and the subcooling heat exchanger 6. The cooling of the heat generating part is made possible. For this reason, the refrigerant circuit is not complicated.

And this Embodiment 1 controls the temperature control valve 8 and the bypass flow control valve 7 at the time of cooling operation, and suppresses the fall of the capability at the time of cooling operation, ensuring the cooling performance of the heat-emitting part of the control apparatus 27. It is characterized by Hereinafter, control of the temperature control valve 8 and the bypass flow control valve 7 will be described.

FIG. 2 is a flowchart showing a flow of control processing during cooling operation in the air conditioning apparatus according to Embodiment 1 of the present invention. The flow of control processing executed by the control device 27 which is a feature of the first embodiment will be described in detail based on FIG.
First, when the switch of the remote control (not shown) for operating the air conditioner is turned on by the user, the compressor 1 starts driving. Cooling operation is started by driving the compressor 1 (step S1).

Whether the measured temperature THHS of the first temperature sensor 18 attached to the heat generating portion of the control device 27 is equal to or higher than a predetermined reference value (for example, 100 ° C.) after a predetermined time has elapsed from the start of operation Is determined (step S2). When the measured temperature THHS is equal to or higher than the reference value, the control device 27 determines that the temperature of the heat generating portion exceeds the allowable temperature, and controls the temperature control valve 8 as follows.

That is, an opening width ΔLEV2 (THHS) corresponding to the measured temperature THHS, and a valve opening command to close the temperature control valve 8 are output to the temperature control valve 8 (step S3). A specific command opening degree LEV2 issued from the control device 27 is an opening degree obtained by the following equation (1).

Command opening LEV2 = LEV2 (NOW)-ΔLEV2 (THHS)
... (1)
LEV2 (NOW): Current temperature control valve 8 opening (equivalent to previous command opening)
ΔLEV2 (THHS): Opening width of LEV2 according to measured temperature THHS

Here, the opening degree width ΔLEV2 (THHS) is a value that increases as the measured temperature THHS increases, and the control device 27 determines the correspondence between the measured temperature THHS and the opening degree width ΔLEV2 (THHS) in advance. Is stored in

Thus, by closing the temperature control valve 8 at the opening width ΔLEV2 (THHS), the pressure and temperature of the refrigerant downstream of the temperature control valve 8 are reduced. That is, the measured temperature THHS is lowered by lowering the temperature of the refrigerant that cools the heat generating portion of the control device 27 to enhance the cooling performance.

The control device 27 determines whether or not the measured temperature THHS falls below the same reference value as step S2 after a predetermined time (step S4). If the measured temperature THHS is not lower than the reference value, the process returns to step S3 again, and the temperature control valve 8 is controlled to close by the opening width ΔLEV2 (THHS) (step S3). Then, the control device 27 repeats the processes of step S3 and step S4 at fixed time intervals until the measured temperature THHS falls below the reference value. Then, when the measured temperature THHS falls below the reference value, the control device 27 shifts to the process of step S5.

In step S5 and subsequent steps, the control device 27 performs corrective action for the adverse effect in the cooling operation by performing the process of step S3. That is, the degree of opening of the temperature control valve 8 is narrowed, which causes an adverse effect that the degree of subcooling is not ensured in the outlet portion of the subcooling heat exchanger 6 in the refrigerant circuit, in other words, the inlet portions of the indoor unit 50a and the indoor unit 50b. there is a possibility. Therefore, processing is performed to correct this adverse effect.

Specifically, first, the control device 27 calculates the subcooling degree SCC1 of the outlet portion of the subcooling heat exchanger 6, and determines whether the subcooling degree SCC1 exceeds 0 ° C. (step S5). The degree of subcooling SCC1 is obtained by subtracting the measurement temperature TH2 of the second temperature sensor 19 from the saturation temperature TC of the high pressure measured by the first pressure sensor 15.

When the degree of supercooling SCC1 is 0 ° C. or less, the degree of supercooling is insufficient, and the indoor units 50a and 50b are in a state where the cooling capacity is insufficient. For this reason, the control device 27 outputs an opening width ΔLEV1 (SCC1) according to the degree of supercooling SCC1 and a valve opening command to open the bypass flow control valve 7 to the bypass flow control valve 7 (step S6). A specific command opening degree issued from the control device 27 is an opening degree obtained by the following equation (2). In addition, since “supercooling degree” refers to a temperature of 0 ° C. or higher, it is not appropriate to express the case where the calculation result of “TC-TH2” is less than 0 ° C. as the subcooling degree SCC1. , I will use this expression.

Command opening LEV1 = LEV1 (NOW)-ΔLEV1 (SCC1)
... (2)
LEV (NOW): Current bypass flow control valve 7 opening (previous command opening)
ΔLEV1 (SCC1): Opening width of LEV1 according to the degree of subcooling SCC1

Here, the opening degree width ΔLEV1 (SCC1) is a value that increases as the absolute value of the subcooling degree SCC1 increases, and the correspondence between the absolute value of the subcooling degree SCC1 and the opening degree width ΔLEV1 (SCC1) The relationship is determined in advance and stored in the control device 27.

As described above, when the subcooling degree SCC1 is 0 ° C. or less in step S5, the control device 27 opens the opening width ΔLEV1 (SCC1) corresponding to the subcooling degree SCC1, and the bypass flow control valve 7. As a result, the amount of refrigerant flowing into the bypass pipe 23 increases. As a result, the amount of heat exchanged in the subcooling heat exchanger 6 increases, the degree of subcooling SCC1 increases, and the process of step S6 is repeated at fixed time intervals until the degree of subcooling SCC1 exceeds 0 ° C. Then, when the degree of subcooling SCC1 exceeds 0 ° C., the process returns to step S2 and the same process is repeated.

As described above, according to the first embodiment, the control device 27 is cooled by the pipe between the outdoor heat exchanger 5 and the subcooling heat exchanger 6 that constitute the refrigerant circuit. There is no need for a dedicated circuit, and cooling of the control device 27 can be performed without causing complication of the refrigerant circuit. Further, by controlling the opening degree of the temperature control valve 8 and the bypass flow control valve 7, it is possible to suppress the performance decrease during the cooling operation while securing the cooling performance of the control device 27. In addition, since the degree of supercooling is secured at the inlet portion of the indoor unit 50 and the refrigerant flowing into the expansion valve 101 becomes the liquid refrigerant, the generation of the refrigerant flow noise can be suppressed.

In the first embodiment, it is determined in step S5 whether the degree of supercooling SCC1 is higher than 0 ° C. However, if there is a degree of supercooling to be secured at the outlet of the subcooling heat exchanger 6, the following You may do so. That is, the degree of subcooling desired to be secured at the outlet of the subcooling heat exchanger 6 may be used as a set value to determine whether the degree of subcooling SCC1 exceeds the set value.

Further, in the first embodiment, the opening width ΔLEV2 (THHS) is a variable width corresponding to the measured temperature THHS, and thereby the measured temperature THHS is rapidly decreased, but the variable width is not necessarily limited. The width may be fixed. The same applies to the opening width ΔLEV1 (SCC1), and it may be a constant width.

Second Embodiment
In the first embodiment described above, the technology for suppressing the decrease in cooling capacity during the cooling operation has been described, but in the second embodiment, the condensation prevention technology for the control device 27 during the heating operation will be described. The differences between the second embodiment and the first embodiment will be mainly described below. The configuration of the air conditioner is the same as that of the first embodiment.

In the cooling operation, the control device 27 is cooled using the high-temperature refrigerant on the high pressure side between the outdoor heat exchanger 5 and the subcooling heat exchanger 6, but in the heating operation, after the pressure is reduced by the expansion valve 101 The controller 27 is cooled using the low temperature refrigerant on the low pressure side of For this reason, in the heating operation, unlike the cooling operation, the measured temperature THHS does not increase excessively. However, conversely, when the temperature of the refrigerant passing through the cooling pipe 40 is too low and the temperature of the control device 27 falls below the dew point temperature of air, dew condensation occurs in the control device 27. Specifically, for example, condensation may occur on a control substrate (not shown) in the control device 27. In this case, there is a possibility that the charging unit mounted on the control board may short-circuit, and the product quality may be impaired as in the cooling operation.

Therefore, the second embodiment is characterized in that the temperature control valve 8 is controlled to prevent such condensation while suppressing the capacity decrease during heating operation. Hereinafter, control of the temperature control valve 8 will be described.

FIG. 3 is a flowchart showing a flow of control processing during heating operation in the air conditioning apparatus according to Embodiment 2 of the present invention. The flow of control processing executed by the control device 27 which is a feature of the second embodiment will be described in detail based on FIG. During the heating operation, the bypass flow control valve 7 is closed so that the refrigerant does not flow through the bypass pipe 23.
First, when the switch of the remote control (not shown) for operating the air conditioner is turned on by the user, the compressor 1 starts driving. The heating operation is started by driving the compressor 1 (step S11).

The control device 27 determines whether condensation may occur in the control device 27 after a predetermined time has elapsed from the start of operation. Specifically, based on the outside air temperature TH3 measured by the third temperature sensor 20 and the temperature of the refrigerant flowing into the cooling pipe 40 measured by the fourth temperature sensor 21 (hereinafter referred to as a measurement temperature TH4), If the following conditional expression (3) is satisfied, it is determined that condensation may occur.

TH3 + α ≧ TH4 (3)
It is assumed that α is selected as the correction value according to the peripheral structure of the charging unit of the control board or the like (step S12).

If TH3 + α is less than TH4, the control device 27 determines that condensation is not likely to occur, and maintains the current opening degree of the temperature control valve 8. On the other hand, when TH3 + α is equal to or greater than TH4, the control device 27 determines that condensation may occur, and controls the temperature control valve 8 as follows.

That is, first, the temperature difference DIFF1 obtained by subtracting the right term from the left term of the conditional expression (3), that is, “(TH3 + α) −TH4”, is calculated to obtain the temperature difference DIFF1. Then, an opening width ΔLEV2 (DIFF1) corresponding to the temperature difference DIFF1 and a valve opening command to close the temperature control valve 8 are output to the temperature control valve 8 (step S13). The specific command opening degree issued from the control device 27 is the opening degree obtained by the following equation (4).

Command opening LEV2 = LEV2 (NOW)-ΔLEV2 (DIFF1)
... (4)
LEV (NOW): Current temperature control valve 8 opening (equivalent to previous command opening)
ΔLEV2 (DIFF1): Opening width of LEV2 according to temperature difference DIFF1

Here, the opening width ΔLEV2 (DIFF1) of LEV2 according to the temperature difference DIFF1 is a value that increases as the temperature difference DIFF1 increases, and the correspondence between the temperature difference DIFF1 and the opening width ΔLEV2 (DIFF1) Are stored in the control unit 27 in advance.

Thus, when it is determined that condensation may occur, the control device 27 closes the opening flow width ΔLEV2 (DIFF1) corresponding to the temperature difference DIFF1, and the bypass flow control valve 7. As a result, the amount of refrigerant passing through the cooling pipe 40 decreases, the pressure and temperature on the upstream side of the temperature control valve 8 rise, and the measured temperature TH4 measured by the fourth temperature sensor 21 rises.

Then, after a predetermined time has elapsed, the control device 27 determines whether TH3 + α is less than TH4 (step S14). If TH3 + α is not smaller than TH4, the process returns to step S13 again to perform control to close the opening width ΔLEV2 (DIFF1) and the bypass flow rate adjusting valve 7. The processes in steps S13 and S14 are repeated at constant time intervals until TH3 + α becomes smaller than TH4. Then, when TH3 + α becomes smaller than TH4, the control device 27 determines that the charging portion of the control board has become equal to or higher than the dew point temperature, that is, determines that condensation can be prevented, and shifts to the process of step S15.

In step S15 and subsequent steps, the control device 27 corrects the harmful effects on the heating operation by performing the process of step S13. That is, when the opening degree of the temperature control valve 8 is narrowed, the opening degree of the expansion valve 101 of the indoor unit 50 becomes insufficient. Finally, the opening of the temperature control valve 8 is too small, so that the flow rate may be insufficient, and the heating capacity may not be sufficiently exhibited.

Therefore, the control device 27 determines whether or not the current operating state is in the unheated state where the heating capacity can not be sufficiently exhibited (step S15). Here, it is determined as follows whether or not it is in the unheated state. That is, when all of the following (1), (2) and (3) are satisfied, it is determined that the heating condition is not reached.

(1) User setting temperature> Indoor unit suction temperature (room temperature)
(2) The driving frequency F of the compressor 1 is lower than the target frequency according to the room temperature.
(3) Saturation temperature converted from the pressure measured by the first pressure sensor 15 = condensation temperature has reached the target condensation temperature. In other words, it is misrecognized that the heating capacity can be demonstrated.

Note that the method of determining the unheated state is not limited to this method, and any method can be adopted.

If it is not in the warm state, the current control is continued and there is no problem. Therefore, the control device 27 returns to step S12 and repeats the control so far. On the other hand, in the case of the unheated state, in order to eliminate the unheated state, the temperature control valve 8 is controlled as follows.

That is, a valve opening degree command to open the temperature control valve 8 by an opening width ΔLEV2 (SCC2) corresponding to the subcooling degree SCC2 at the outlet of the indoor heat exchanger 100 is output to the temperature control valve 8 (step S16). The degree of subcooling SCC2 is obtained by subtracting the measured temperature TH5 of the second temperature sensor 19 from the saturation temperature TC of the high pressure measured by the first pressure sensor 15. A specific command opening degree LEV2 issued from the control device 27 is an opening degree obtained by the following equation (5).

Command opening LEV2 = LEV2 (NOW) + ΔLEV2 (SCC2)
... (5)
LEV (NOW): Current temperature control valve 8 opening (previous command opening)
ΔLEV2 (SCC2): Opening width of LEV2 according to the degree of subcooling SCC2

Here, the opening degree width ΔLEV2 (SCC2) is a value that increases as the subcooling degree SCC2 increases, and the correspondence relationship between the subcooling degree SCC2 and the opening degree width ΔLEV2 (SCC2) is determined in advance and controlled. It is stored in the device 27.

As described above, the temperature control valve 8 is opened by the opening width ΔLEV2 (SCC2) corresponding to the degree of subcooling SCC2. Thereby, the flow rate of the refrigerant flowing to the indoor heat exchanger 100 is increased. Then, the control device 27 repeats the process of step S16 at fixed time intervals until the unheated state is resolved. Then, when the unheated state is eliminated, the control device 27 returns to step S12 and repeats the same processing.

As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained, and the opening control of the temperature control valve 8 prevents condensation during heating operation and suppresses the reduction of the heating capacity. Is possible.

Reference Signs List 1 compressor, 2 oil separator, 3 check valve, 4 four-way valve, 5 outdoor heat exchanger, 6 subcooling heat exchanger, 7 bypass flow control valve, 8 temperature control valve, 9 liquid side on-off valve, 10 outdoor unit , 11 gas side open / close valve, 12 accumulator, 13 oil return bypass capillary, 14 solenoid valve for oil return, 15 first pressure sensor, 18 first temperature sensor, 19 second temperature sensor, 20 third temperature sensor, 21 first 4 temperature sensor, 23 bypass piping, 24 connection points, 25 connection points, 26 fluid piping, 27 control devices, 30 oil return bypass circuit, 40 cooling piping, 50 indoor units, 50a indoor units, 50b indoor units, 100a indoor heat exchange , 100b indoor heat exchanger, 101a expansion valve, 101b expansion valve, 102a controller, 102b controller, 03a fifth temperature sensor, 103b fifth temperature sensor, 204 a gas pipe, 205 liquid pipe, 206a gas branch pipe, 206 b gas branch pipe, 207a liquid branch pipes, 207b liquid branch pipe.

Claims

A refrigerant circuit in which a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected by piping to circulate a refrigerant;
A controller for controlling the refrigerant circuit;
A bypass pipe branched from between the outdoor heat exchanger and the expansion valve and connected to the suction side of the compressor;
A bypass flow control valve provided in the bypass pipe;
A subcooling heat exchanger that exchanges heat between the refrigerant between the outdoor heat exchanger and the expansion valve and the refrigerant downstream of the bypass flow control valve of the bypass pipe;
Among the pipes between the outdoor heat exchanger and the subcooling heat exchanger, a cooling pipe which is disposed in contact with the control device to cool the control device;
And a temperature control valve provided between the outdoor heat exchanger and the cooling pipe, for adjusting the temperature of the refrigerant passing through the cooling pipe.
The control device controls the temperature control valve so that the temperature of the heat generating portion of the control device becomes lower than a preset reference value during cooling operation, and the degree of supercooling of the outlet of the subcooling heat exchanger An air conditioner controlling the bypass flow control valve so that the value exceeds a preset set value.
When the temperature of the heat generating portion is equal to or higher than the reference value, the control device repeatedly performs an operation of reducing the opening degree of the temperature control valve until the temperature of the heat generating portion becomes lower than the reference value.
When the temperature of the heat generating part is less than the reference value, and the degree of subcooling of the outlet of the subcooling heat exchanger is less than the set value, the operation of increasing the opening degree of the bypass flow control valve is The air conditioner according to claim 1, wherein the air conditioning apparatus is repeated until the degree of subcooling exceeds the set value.
It has a four-way valve that enables the cooling operation and the heating operation by switching the flow of the refrigerant in the refrigerant circuit,
The control device controls the temperature control valve so that condensation does not occur in the control device due to cooling by the cooling pipe during the heating operation, and the operating condition in the refrigerant circuit can not exhibit the heating capacity. The air conditioning apparatus according to claim 1 or 2, wherein the temperature control valve is controlled so as not to occur.
When condensation may occur in the control device, the control device repeatedly performs the operation of reducing the opening degree of the temperature adjustment valve until the possibility of condensation is eliminated.
If there is no possibility that condensation will occur, and the operating condition in the refrigerant circuit is the unwarmed condition, the operation of opening the opening degree of the temperature control valve is repeated until the unheated condition is eliminated. The air conditioner according to Item 3.
An outside air temperature sensor that measures the outside air temperature,
A cooling refrigerant temperature sensor that measures the temperature of the refrigerant flowing into the cooling pipe during the heating operation;
The air conditioning apparatus according to claim 4, wherein the control device determines whether condensation may occur in the control device based on the temperature measured by the outside air temperature sensor and the temperature measured by the cooling refrigerant temperature sensor.