KR20060094803A - Second-refrigerant pump driving type air conditioner - Google Patents

Abstract

The present invention relates to a secondary refrigerant pump driven air conditioner, comprising: an indoor unit having an indoor heat exchanger; A compressor, a first outdoor heat exchanger configured to heat-exchange the refrigerant discharged from the compressor with the refrigerant via the indoor unit, an outdoor expansion valve in which the refrigerant passing through the first outdoor heat exchanger is expanded under reduced pressure, and the outdoor expansion valve. A first refrigerant circulation unit having a second outdoor heat exchanger through which the refrigerant passing through the air exchanges with the outdoor air; A unit heat exchanger configured to exchange heat between the refrigerant via the indoor heat exchanger and the first outdoor heat exchanger, a receiver temporarily receiving the refrigerant via the inter-unit heat exchanger, and send the refrigerant of the receiver to the indoor unit. And a second refrigerant circulation unit provided with a pump. As a result, a secondary refrigerant pump driven air conditioner capable of heating operation and reducing constraints on the length and size of the connecting pipe connecting the outdoor unit and the indoor unit and suppressing the occurrence of oil shortage of the compressor is provided. do.

Description

Secondary refrigerant pump driven air conditioner {SECOND-REFRIGERANT PUMP DRIVING TYPE AIR CONDITIONER}

1 is a configuration diagram of a conventional air conditioner,

2 is a configuration diagram of a secondary refrigerant pump driving type air conditioner according to an embodiment of the present invention;

3 is a control block diagram of FIG.

4 is a view illustrating main parts of a secondary refrigerant pump driving type air conditioner according to another embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: indoor unit 11: indoor heat exchanger

13: Indoor heat exchanger middle temperature sensor 15: Indoor heat exchanger exit temperature sensor

17: indoor heat exchanger flow control valve 20: first refrigerant circulation unit

21: Compressor 22: High Pressure Detection Sensor

25: first outdoor heat exchanger 26: first outdoor heat exchanger inlet temperature sensor

28: first outdoor heat exchanger outlet temperature sensor 29: second outdoor heat exchanger

31: First 4-way valve 32: Second outdoor heat exchanger outlet temperature sensor

40: second refrigerant circulation unit 41: unit heat exchanger

43: Unit heat exchanger outlet temperature sensor 44: Unit heat exchanger outlet pressure sensor

45: receiver 46: refrigerant level sensor

48: pump 50: second four-way valve

52: pump outlet pressure sensor 61: supercooler

62: Subcooler inlet temperature sensor 63: Subcooler outlet temperature sensor

64: supercooler outlet temperature sensor 65: input current detector

71: control unit 72: first outdoor heat exchanger subcooling calculation unit

74: unit heat exchanger overheat calculation unit 76: indoor heat exchanger overcooling unit

78: subcooler subcooling calculation unit 80: compressor superheat calculation unit

The present invention relates to a secondary refrigerant pump drive type air conditioner, and more particularly, heating operation is possible, and it is possible to reduce the length and size constraints of the connecting pipe connecting the outdoor unit and the indoor unit, and the oil shortage phenomenon of the compressor. It is related with the secondary refrigerant pump drive type air conditioner which can suppress this generation.

1 is a block diagram of a conventional air conditioner. As shown in the drawing, the air conditioner includes a plurality of indoor units 110 and a plurality of outdoor units 120 that adequately provide a coolant according to the operating state of each indoor unit 110.

Each indoor unit 110 includes an indoor heat exchanger 111 disposed to exchange heat with the indoor air, and an indoor expansion device 113 disposed so that the refrigerant can be expanded under reduced pressure on the inlet side of the indoor heat exchanger 111. Each is equipped.

Each outdoor unit 120 is composed of a compressor 121 for compressing a refrigerant and an outdoor heat exchanger 127 on which one side of the compressor 121 is arranged to exchange heat with the outdoor air. An accumulator 123 is provided on the suction side of the compressor 121 to suck gaseous refrigerant, and a four-way valve 125 is provided on the discharge side of the compressor 121 so as to switch the flow path of the refrigerant. An outdoor expansion device 129 is installed at one side of the outdoor heat exchanger 127 along the flow direction of the refrigerant, and a bypass passage 131 having a check valve 133 is formed at one side of the outdoor expansion device 129. It is.

By this configuration, the outdoor unit 120 is selectively driven according to the load of the indoor unit 110 to be operated, and each of the four-way valves 125 of the outdoor unit 120 to be operated are the operation modes of the indoor unit 110. The flow path of the refrigerant is switched accordingly. When the indoor unit 110 is cooled and operated, the four-way valve 125 of the outdoor unit 120 that is operated switches the flow path so that the refrigerant discharged from the compressor 121 passes through the outdoor heat exchanger 127 and the outdoor heat exchanger. The refrigerant passing through 127 is expanded under reduced pressure while passing through the indoor expansion device 113 of the indoor unit 110 that is operated, and then performs a cooling operation while heat-exchanging with indoor air in the indoor heat exchanger 111. The refrigerant that performs the cooling action is sucked into the compressor 121 via the four-way valve 125 and the accumulator 123 of the outdoor unit 120 to be operated, and the process of compressing and discharging is repeated.

However, in the conventional air conditioner, the compressor 121 is filled with oil together with the refrigerant to cool and lubricate the compressor 121, so that the indoor heat exchanger 111 and the indoor unit 110 are sealed. ) And the interior of the connection pipe connecting the outdoor unit 120, the oil is interspersed, and the outdoor unit via the indoor unit 110 for smooth recovery of the oil inside the indoor heat exchanger 111 and the connection pipe. There is a problem in that the diameter of the gas pipe returned to 120 cannot be increased by more than a certain degree, and the limitation of the installation distance between the outdoor unit 120 and the indoor unit 110 occurs.

In addition, there is a problem that the heating operation is stopped at the time of heating operation of the indoor unit 110, as well as causing noise during the oil recovery operation for recovering oil remaining in the indoor heat exchanger 111 and the connection pipe periodically.

Accordingly, an object of the present invention is to operate a secondary refrigerant pump capable of heating operation and reducing the restriction on the length and size of the connecting pipe connecting the outdoor unit and the indoor unit and suppressing the occurrence of oil shortage of the compressor. It is to provide a type air conditioner.

The object is, according to the present invention, an indoor unit having an indoor heat exchanger; A compressor, a first outdoor heat exchanger configured to heat-exchange the refrigerant discharged from the compressor with the refrigerant via the indoor unit, an outdoor expansion valve in which the refrigerant passing through the first outdoor heat exchanger is expanded under reduced pressure, and the outdoor expansion valve. A first refrigerant circulation unit having a second outdoor heat exchanger in which the refrigerant passing through the air exchanges with the outdoor air; A unit heat exchanger configured to exchange heat between the refrigerant via the indoor heat exchanger and the first outdoor heat exchanger, a receiver temporarily receiving the refrigerant via the inter-unit heat exchanger, and send the refrigerant of the receiver to the indoor unit. A second refrigerant pump driven type air conditioner is provided, comprising a second refrigerant circulation unit with a pump.

Herein, it is preferable to further include a subcooler for allowing the refrigerant via the indoor heat exchanger to be supercooled.

It is effective to further include a control unit for controlling the supercooler to suppress the introduction of the refrigerant in the gas state into the pump.

Based on the detection results of the subcooler inlet pressure sensor for detecting the inlet pressure of the subcooler, the subcooler outlet temperature sensor for detecting the outlet temperature of the subcooler, the subcooler inlet pressure sensor, and the subcooler outlet temperature sensor It is preferable to further include a subcooler subcooling calculation unit for detecting the outlet subcooling degree of the subcooler.

And a subcooler inlet temperature sensor for detecting the inlet temperature of the subcooler, wherein the subcooler overcooling degree calculation unit is based on a detection result of the subcooler inlet temperature sensor and the subcooler inlet pressure sensor. The supercooling degree is calculated, and the controller is effective to control the subcooler so that the outlet subcooling degree of the subcooler becomes a predetermined value or more when the subcooler inlet subcooling degree is lower than a predetermined value.

One side is preferably connected to the inlet side of the subcooler and the other side preferably further comprises a subcooler bypass passage connected to the outlet side of the subcooler.

And a subcooler inlet opening / closing valve disposed to open and close the inlet side of the subcooler at a downstream side of the branch point of the bypass passage along the flow direction of the refrigerant, and a subcooler bypass passage opening and closing valve for opening and closing the subcooler bypass passage. The control unit may effectively control the subcooler inlet opening and closing valve and the subcooler bypass flow path opening and closing valve such that the refrigerant bypasses the subcooler when the inlet side supercooling degree of the subcooler is greater than or equal to a predetermined level.

The unit heat exchanger between the unit heat exchanger outlet pressure sensor for detecting the outlet pressure of the unit heat exchanger, the unit heat exchanger outlet temperature sensor for detecting the outlet temperature of the unit heat exchanger, and the outlet pressure and the outlet temperature of the unit heat exchanger. Further comprising a unit heat exchanger overheat calculation unit for calculating the outlet superheat degree of the exchanger, wherein the control unit preferably controls the rotational speed of the pump so that the calculated outlet superheat of the unit heat exchanger is a target superheat.

And a pump outlet pressure sensor for detecting the outlet pressure of the pump, and an inter-unit heat exchanger outlet pressure sensor for detecting the outlet pressure of the inter-unit heat exchanger, wherein the controller is configured such that the pump outlet pressure is greater than the outlet pressure of the inter-unit heat exchanger. It is effective to control the rotation speed of the pump so as to be small.

The apparatus may further include an input current detector configured to detect an input current of the pump, wherein the controller controls the rotation speed of the pump based on a result detected by the input current detector.

And a refrigerant level sensor for detecting a liquid refrigerant level inside the receiver, wherein the controller is configured to suppress the inflow of gaseous refrigerant into the pump based on a detection result of the refrigerant level sensor. It is effective to control it.

The apparatus may further include a high pressure detection sensor that detects the discharge side pressure of the compressor, and the control unit controls the compression capacity of the compressor with the discharge side high pressure target value of the compressor.

A first outdoor heat exchanger inlet temperature sensor and a first outdoor heat exchanger outlet temperature sensor for detecting a temperature of an inlet and an outlet of the first outdoor heat exchanger, and the first outdoor heat exchanger based on an inlet and an outlet temperature of the first outdoor heat exchanger; The first outdoor heat exchanger subcooling calculation unit for calculating the outlet side supercooling degree of the outdoor heat exchanger, and the compressor superheat calculation unit for calculating the superheat degree of the suction side refrigerant of the compressor, the control unit is the first When the outlet side supercooling degree of the outdoor heat exchanger exceeds a predetermined value and the suction side superheat degree of the compressor exceeds a predetermined value, it is effective to control the opening degree of the outdoor expansion valve to be increased.

An indoor heat exchanger flow control valve disposed on one side of the indoor heat exchanger along a flow direction of the refrigerant, an intermediate temperature sensor for detecting an intermediate temperature of the indoor heat exchanger, and an outlet temperature of the indoor heat exchanger; And an indoor heat exchanger supercooling calculation unit configured to calculate an overcooling degree of the indoor heat exchanger based on an indoor heat exchanger outlet temperature sensor and an intermediate temperature of the indoor heat exchanger and an outlet temperature of the indoor heat exchanger. It is preferable to control the indoor heat exchanger flow rate control valve so that the subcooling degree of the indoor heat exchanger is a target overcooling degree.

And a unit heat exchanger outlet pressure sensor for detecting an outlet pressure of the unit heat exchanger, wherein the indoor heat exchanger and the coolant calculating unit are based on the outlet pressure of the unit heat exchanger and the outlet temperature of the indoor heat exchanger. It is effective to calculate the exit subcooling of the group.

The control unit controls the opened indoor heat exchanger flow rate control valve to open when the overcooling degree of the indoor heat exchanger of the stationary indoor unit calculated by the indoor heat exchanger and the cooling degree calculation unit exceeds a set value. It is preferable to allow the liquid refrigerant inside the indoor heat exchanger of the unit to be recovered.

A first four-way valve connected to the discharge side of the compressor to switch the flow path of the refrigerant of the first refrigerant circulation unit and a second four-way valve disposed on the discharge side of the pump to switch the flow path of the refrigerant of the second refrigerant circulation unit; It is effective to include more.

The compressor may be configured in plural, and during control of the compressor, the controller may control the rotational speed of the pump to correspond to the capacity of the compressor to be operated, and then drive the compressor to be operated.

The compressor includes an inverter compressor and a constant speed compressor, and the controller controls the rotation speed of the pump to correspond to the lowest frequency of the inverter compressor before controlling the inverter compressor to the lowest frequency for driving the constant speed compressor. After that, it is effective to control the inverter compressor to the lowest frequency.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

2 is a block diagram of a secondary refrigerant pump driving type air conditioner according to an embodiment of the present invention, Figure 3 is a control block diagram of Figure 2, Figure 4 is a secondary refrigerant pump driving according to another embodiment of the present invention The main part of a type | mold air conditioner is shown. As shown in these figures, the secondary refrigerant pump drive type air conditioner includes: an indoor unit 10 having an indoor heat exchanger 11; The compressor 21 and the refrigerant discharged from the compressor 21 pass through the first outdoor heat exchanger 25 and the first outdoor heat exchanger 25 formed to exchange heat with the refrigerant via the indoor unit 10. A first refrigerant circulation unit comprising a first outdoor expansion valve (27) in which the refrigerant expands under reduced pressure, and a second outdoor heat exchanger (29) in which the refrigerant passing through the first outdoor expansion valve (27) exchanges heat with outdoor air. 20); The unit heat exchanger 41 formed so that the refrigerant via the indoor heat exchanger 11 exchanges heat with the first outdoor heat exchanger 25, and the receiver 45 temporarily receiving the refrigerant via the inter-unit heat exchanger 41. And a second refrigerant circulation unit 40 having a pump 48 for discharging the refrigerant of the receiver 45 to the indoor unit 10.

Here, the first refrigerant circulation unit 20 and the second refrigerant circulation unit 40 is preferably composed of an outdoor unit disposed outdoors. The first refrigerant circulation unit 20 is configured to circulate oil together with the refrigerant inside the compressor 21 for lubrication and cooling of the compressor 21, and the second refrigerant circulation unit 40 does not include oil. The refrigerant is configured to circulate.

Each indoor unit 10 includes an indoor heat exchanger 11 arranged to exchange heat with indoor air, and an indoor heat exchanger flow control valve 17 installed to adjust a flow rate of a refrigerant on one side of the indoor heat exchanger 11. ). The middle temperature sensor 13 of the indoor heat exchanger is installed at an intermediate point of each indoor heat exchanger 11 along the flow direction of the refrigerant to detect the temperature of the refrigerant, and the refrigerant at the outlet side of the indoor heat exchanger 11. Each of the indoor heat exchanger outlet temperature sensors 15 is provided to detect the outlet temperature of the outlet.

The first refrigerant circulation unit 20 includes a compressor 21 for compressing a refrigerant and a refrigerant connected to the discharge side of the compressor 21 so that the compressed refrigerant can be heat-exchanged with the refrigerant via the indoor unit 10. The outdoor air exchanger (25), the first outdoor expansion valve (27) through which the refrigerant passing through the first outdoor heat exchanger (25) under reduced pressure expansion, and the refrigerant via the first outdoor expansion valve (27) are the outdoor air. And a second outdoor heat exchanger (29) which exchanges heat with each other. Here, the compressor 21 may be configured in plural, at least one of which may be configured as an inverter compressor having a variable speed.

On the suction side of the compressor 21, an accumulator 23 for providing a refrigerant in gaseous state, a compressor suction temperature sensor 38 and a compressor suction pressure sensor 39 for detecting the suction side temperature and pressure, respectively, are provided. On the discharge side of the compressor 21, a high pressure detection sensor 22 for detecting the discharge side pressure and a first four-way valve 31 for switching the flow path of the refrigerant are provided. The first outdoor heat exchanger inlet temperature sensor 26 and the first outdoor heat exchanger outlet temperature sensor 28 are provided at the inlet side and the outlet side of the first outdoor heat exchanger 25 so as to detect the temperature of the refrigerant, respectively. , The second outdoor expansion valve bypass passage including a second outdoor expansion valve 35 and a check valve 37 in which the refrigerant is decompressed and expanded at the inflow side of the first outdoor heat exchanger 25 along the flow direction of the refrigerant during the cooling operation. 36 is formed. One side of the second outdoor heat exchanger 29 is provided with a first outdoor expansion valve 27 to allow the refrigerant to expand under reduced pressure during the heating operation.

The second refrigerant circulation unit 40 includes a unit heat exchanger 41 and a unit heat exchanger 41 formed such that a refrigerant via the indoor heat exchanger 11 can exchange heat with the first outdoor heat exchanger 25. A receiver 45 temporarily receiving the refrigerant, a pump 48 for pumping the refrigerant from the receiver 45 to the indoor unit 10 to be operated, and an outlet side of the pump 48 are disposed at the outlet of the refrigerant. A second four-way valve 50 for switching the flow path and a subcooler 61 disposed in an upstream side of the receiver 45 along the flow direction of the coolant during the heating operation to supercool the coolant.

An inter-unit heat exchanger outlet temperature sensor 43 and an inter-unit heat exchanger outlet pressure sensor 44 are respectively installed at the outlet side of the inter-unit heat exchanger 41 so as to detect the outlet temperature and pressure of the inter-unit heat exchanger 41, respectively. have.

The receiver 45 is provided with a refrigerant level sensor 46 so as to detect the level of liquid refrigerant therein, and a pump outlet pressure sensor 52 is provided at the discharge side of the pump 48 so as to detect pressure. . A check valve 49 is provided between the pump 48 and the second four-way valve 50 to prevent backflow.

The inlet side of the subcooler 61 is provided with a subcooler inlet temperature sensor 62 and a subcooler inlet pressure sensor 63 so as to detect the temperature and pressure of the refrigerant, respectively, and on the outlet side of the subcooler 61. The supercooler outlet temperature sensor 64 is provided to detect the outlet temperature. Here, as shown in FIG. 4, the subcooler bypass passage 66 may bypass the subcooler 61 when the refrigerant passing through the second four-way valve 50 is sufficiently overcooled on one side of the subcooler 61. And a subcooler inlet opening and closing valve 68 and a subcooler bypass passage opening and closing valve 67 to selectively open and close the inlet side and the subcooler bypass flow passage 66 of the subcooler 61. .

On the other hand, the compressor 21, the first outdoor expansion valve 27 and the second outdoor expansion valve 35, the pump 48 and the indoor heat exchanger flow rate control valve 17, the operation mode, the load variation and The control unit 71 is connected to control them according to the state of the refrigerant. The control unit 71 includes the subcooling of the first outdoor heat exchanger 25, the superheating of the unit heat exchanger 41, the subcooling of the indoor heat exchanger 11, the subcooling of the subcooler 61, and the compressor 21. The first outdoor heat exchanger subcooling calculation unit 72, the unit heat exchanger superheat calculation unit 74, the indoor heat exchanger subcooling calculation unit 76, and the supercooling unit to calculate the superheat degree of the suction side of the It is implemented in the form of a microcomputer equipped with a control program by including a coolant cooling calculation unit 78 and a compressor superheat calculation unit 80.

The control unit 71 includes an input current detection unit 65 for detecting a change in the input current of the pump 48, a refrigerant level sensor 46, a high pressure detection sensor 22, a compressor suction temperature sensor 38, and a compressor. Suction pressure sensor 39, the first outdoor heat exchanger inlet temperature sensor 26 and the first outdoor heat exchanger outlet temperature sensor 28, the unit heat exchanger outlet temperature sensor 43 and the unit heat exchanger outlet pressure sensor ( 44, the indoor heat exchanger intermediate temperature sensor 13 and the indoor heat exchanger outlet temperature sensor 15, the pump outlet pressure sensor 52, the supercooler inlet temperature sensor 62, and the supercooler inlet pressure sensor 63 ) And the supercooler outlet temperature sensor 64 are electrically connected to each other.

By such a configuration, when the heating operation of the indoor unit 10 is selected, the control unit 71 controls the compressor 21 and the first four-way valve 31 to correspond to the load of the indoor unit 10 to be operated, thereby controlling the first operation. As shown by the dotted arrows in FIG. 2, the refrigerant of the refrigerant circulation unit 20 is circulated, and the refrigerant of the second refrigerant circulation unit 40 is controlled by controlling the pump 48 and the second four-way valve 50. 2 is circulated to allow the indoor unit 10 to perform the heating function.

The control unit 71 compares the detection result detected by the high pressure detection sensor 22 with the high pressure target value of the discharge side of the compressor 21 and the high pressure target value, and adjusts the rotation speed of the compressor 21 so that the discharge side pressure converges to the high pressure target value. To control.

The refrigerant compressed and discharged from the compressor 21 is introduced into the first outdoor heat exchanger 25 via the first four-way valve 31, and condensed while being exchanged with the refrigerant via the indoor heat exchanger 11. The refrigerant flows along the second outdoor expansion valve 35 and the second outdoor expansion valve bypass passage 36, expands under reduced pressure through the first outdoor expansion valve 27, and flows into the second outdoor heat exchanger 29. do. The refrigerant heat-exchanged with the outdoor air in the second outdoor heat exchanger (29) is repeatedly sucked into the compressor (21) via the accumulator (23) and compressed and discharged.

At this time, the first outdoor heat exchanger and the coolant calculation unit 72 are configured based on the detection results of the first outdoor heat exchanger inlet temperature sensor 26 and the first outdoor heat exchanger outlet temperature sensor 28. The supercooling degree of (25) is calculated, and the compressor overheat calculation unit (80) is based on the results detected by the compressor suction temperature sensor (38) and the compressor suction pressure sensor (39). To calculate. The control unit 71 increases the opening degree of the first outdoor expansion valve 27 when the calculated outlet supercooling degree of the first outdoor heat exchanger 25 is equal to or greater than the set value and the suction side superheat degree of the compressor 21 is equal to or greater than the set value. The first outdoor expansion valve 27 is controlled so as to increase the refrigerant circulation amount of the first refrigerant circulation unit 20.

When the pump 48 is driven, the liquid refrigerant inside the receiver 45 flows to the unit heat exchanger 41 via the pump 48 being operated and the check valve 49 and the second four-way valve 50. Heat exchange with the first outdoor heat exchanger (25). When the driving of the pump 48 is started, the input current detector 65 detects an input change of the pump 48, and the coolant level sensor 46 detects the level of the liquid refrigerant inside the receiver 45. . The pump outlet pressure sensor 52 detects the discharge side pressure of the pump 48, and the inter-unit heat exchanger outlet temperature sensor 43 and the inter-unit heat exchanger outlet pressure sensor 44 are the outlet temperature of the inter-unit heat exchanger 41 and Each pressure is detected. The inter-unit heat exchanger overheat calculation unit 74 converts the detected outlet-side pressure into a temperature and calculates the outlet side supercooling degree of the inter-unit heat exchanger 41 from the two temperatures.

The control part 71 controls the rotation speed of the pump 48 so that the detected discharge pressure of the pump 48 may become larger than the outlet pressure of the inter-unit heat exchanger 41, and also detects it by the input current detector 65. When the state in which the input fluctuation exceeds the predetermined value is maintained for a predetermined time or more, the rotation speed of the pump 48 is reduced to prevent the flow of refrigerant in the gas phase into the pump 48. In addition, when the level of the liquid refrigerant detected by the refrigerant level sensor 46 is reduced to a predetermined level (lower limit), the control unit 71 controls to suppress or reduce the increase in the frequency of the pump 48 so that the refrigerant in the gas state is reduced. It is suppressed to flow into the pump 48. The control unit 71 causes the rotation speed of the pump 48 to increase when the outlet superheat degree of the inter-unit heat exchanger 41 calculated by the inter-unit heat exchanger overheat calculation unit 74 increases, and when the calculated superheat degree decreases. The discharge amount of the pump 48 is controlled so that the rotation speed of the pump 48 is reduced.

The refrigerant heat-exchanged with the first outdoor heat exchanger (25) in the unit heat exchanger (41) flows to the indoor unit (10) being operated and heat exchanges with indoor air in the indoor heat exchanger (11) to perform a heating operation. The refrigerant having been heated is flowed to the supercooler 61 via the indoor heat exchanger flow rate control valve 17 and the second four-way valve 50. At this time, the indoor heat exchanger intermediate temperature sensor 13 and the indoor heat exchanger outlet temperature sensor 15 detect the temperature at the middle point of the indoor heat exchanger 11 and the outlet side temperature, respectively, and the indoor heat exchanger and the coolant calculation unit. Reference numeral 76 calculates the supercooling degree of the indoor heat exchanger 11 from the detected intermediate temperature and the outlet temperature of the indoor heat exchanger 11.

The control unit 71 causes the opening degree of the indoor heat exchanger flow rate control valve 17 to increase when the subcooling degree calculated by the indoor heat exchanger subcooling calculation unit 76 is increased to converge to the target subcooling. When the degree of supercooling decreases, the indoor heat exchanger flow rate control valve 17 is controlled to reduce the opening degree of the indoor heat exchanger flow rate control valve 17. Here, the control unit 71 converts the outlet pressure of the unit heat exchanger 41 into a saturation temperature and subcools the difference between the converted temperature and the outlet temperature of the indoor heat exchanger 11 at the outlet side of the indoor heat exchanger 11. It may also be defined to control the indoor heat exchanger flow rate control valve 17. In addition, the control unit 71 calculates the supercooling degree of the indoor heat exchanger 11 of the stationary indoor unit 10 when the subcooling degree of the stationary indoor heat exchanger 11 calculated exceeds the set value, A liquid refrigerant recovery operation may be performed in which the heat exchanger flow rate control valve 17 is opened to recover the liquid refrigerant condensed inside the indoor heat exchanger 11.

The refrigerant flowed into the subcooler 61 is radiated and condensed in the subcooler 61, flows into the receiver 45, and is sent out to the indoor unit 10 by the pump 48. At this time, the subcooler inlet temperature sensor 62, the subcooler inlet pressure sensor 63, and the subcooler outlet temperature sensor 64 detect the inlet side temperature and the pressure and the outlet side temperature of the supercooler 61, respectively. The subcooler supercooling degree calculating unit 78 converts the inlet pressure of the subcooler 61 into a saturation temperature and converts the inlet side supercooling degree of the subcooler 61 from the converted temperature, the detected inlet temperature, and the detected outlet temperature. The outlet side supercooling degree of the subcooler 61 is computed, respectively. The controller 71 controls the supercooling amount of the subcooler 61 so that the refrigerant is subcooled when the inlet subcooling degree of the subcooler 61 is lower than or equal to the set value. Here, as shown in FIG. 4, the subcooler bypass passage 66, the subcooler inlet opening and closing valve 68, and the subcooler bypass passage opening and closing valve 67 are provided, and the inlet side supercooling degree of the subcooler 61 is provided. When the value is greater than or equal to the set value, the control unit 71 controls the subcooling inlet opening and closing valve 68 and the subcooling bypass flow channel opening and closing valve 67 to allow the refrigerant to flow along the subcooling bypass circuit 66.

On the other hand, when the load of the indoor unit 10 increases and the amount of heat of evaporation of the inter-unit heat exchanger 41 increases, the outlet superheat degree of the inter-unit heat exchanger 41 decreases. When the amount of heat of evaporation of the unit heat exchanger 41 is increased, the condensation pressure of the first outdoor heat exchanger 25 of the first refrigerant circulation unit 20 decreases and the inlet pressure of the compressor 21 decreases. At this time, it is preferable that the control unit 71 cause the control of the rotation speed of the compressor 21 to precede the control of the rotation speed of the pump 48.

In addition, when the load of the indoor unit 10 is reduced and the supercooling degree of the indoor heat exchanger 11 is reduced, the control unit 71 lowers the rotation speed of the pump 48 to maintain the gas state inside the pump 48. To prevent refrigerant from entering.

In addition, when the compression capacity of the compressor 21 is changed for the safety control of the first refrigerant circulation unit 20, the control unit 71 may prevent the refrigerant in the gaseous state from flowing into the pump 48. Preferably, the rotation speed control of the pump 48 can be carried out prior to the change of the capacity of (21).

For example, when the first refrigerant circulation unit 20 is configured to include a plurality of compressors 21 so that the equalizing operation between the compressors 21 is performed, the control unit 71 is the compressors 21 to be alternately operated. After the control of the rotational speed of the pump 48 is made to correspond to the compression capacity of), the compressor 21 to be operated is controlled to be driven.

In addition, when the compressor 21 includes a plurality of inverters including at least one inverter compressor, and the inter compressor is reduced to the lowest operating frequency to drive the constant speed compressor, the control unit 71 before the drive of the constant speed compressor is performed. After the rotational speed control of the pump 48 is controlled to correspond to the lowest frequency of the reduced inverter compressor, the constant speed compressor is controlled to be driven.

As described above, according to the present invention, an indoor unit having an indoor heat exchanger; A compressor, a first outdoor heat exchanger configured to exchange heat between the refrigerant discharged from the compressor and the refrigerant via the indoor unit, an outdoor expansion valve in which the refrigerant passing through the first outdoor heat exchanger is expanded under reduced pressure, and a refrigerant via the outdoor expansion valve. A first refrigerant circulation unit having a second outdoor heat exchanger for heat exchange with outdoor air; A unit heat exchanger in which the refrigerant via the indoor heat exchanger is heat-exchanged with the first outdoor heat exchanger, a receiver temporarily receiving the refrigerant via the inter-unit heat exchanger, and a pump for delivering the refrigerant from the receiver to the indoor unit. By including the refrigerant circulation unit, the secondary refrigerant pump can be heated and reduce the restriction on the length and size of the connecting pipe connecting the outdoor unit and the indoor unit, and can suppress the occurrence of oil shortage in the compressor. A driven air conditioner is provided.

Claims (19)

An indoor unit having an indoor heat exchanger; A compressor, a first outdoor heat exchanger configured to heat-exchange the refrigerant discharged from the compressor with the refrigerant via the indoor unit, an outdoor expansion valve in which the refrigerant passing through the first outdoor heat exchanger is expanded under reduced pressure, and the outdoor expansion valve. A first refrigerant circulation unit having a second outdoor heat exchanger through which the refrigerant passing through the air exchanges with the outdoor air; A unit heat exchanger configured to exchange heat between the refrigerant via the indoor heat exchanger and the first outdoor heat exchanger, a receiver temporarily receiving the refrigerant via the inter-unit heat exchanger, and send the refrigerant of the receiver to the indoor unit. A second refrigerant pump-driven air conditioner comprising a second refrigerant circulation unit having a pump. The method of claim 1, And a subcooler for supercooling the refrigerant via the indoor heat exchanger. The method of claim 2, And a control unit for controlling the supercooler so that the refrigerant in the gaseous state is prevented from flowing into the pump. The method of claim 3, Based on the detection results of the subcooler inlet pressure sensor for detecting the inlet pressure of the subcooler, the subcooler outlet temperature sensor for detecting the outlet temperature of the subcooler, the subcooler inlet pressure sensor, and the subcooler outlet temperature sensor And a subcooler subcooling calculation unit configured to detect an outlet subcooling degree of the subcooler. The method of claim 4, wherein And a subcooler inlet temperature sensor for detecting the inlet temperature of the subcooler, wherein the subcooler overcooling degree calculation unit is based on a detection result of the subcooler inlet temperature sensor and the subcooler inlet pressure sensor. And calculating a supercooling degree, wherein the controller controls the subcooler so that the outlet subcooling degree of the subcooler becomes a predetermined value or more when the subcooler inlet subcooling degree is lower than or equal to a predetermined value. The method of claim 5, One side is connected to the inlet side of the subcooler and the other side is a secondary refrigerant pump driven air conditioner further comprises a subcooler bypass passage connected to the outlet side of the subcooler. The method of claim 6, And a subcooler inlet opening / closing valve disposed to open and close the inlet side of the subcooler at a downstream side of the branch point of the bypass passage along the flow direction of the refrigerant, and a subcooler bypass passage opening and closing valve for opening and closing the subcooler bypass passage. And the control unit controls the subcooler inlet opening and closing valve and the subcooler bypass flow path opening and closing valve such that the refrigerant bypasses the subcooler when the inlet side supercooling degree of the subcooler is greater than or equal to a predetermined level. group. The method of claim 3, The unit heat exchanger between the unit heat exchanger outlet pressure sensor for detecting the outlet pressure of the unit heat exchanger, the unit heat exchanger outlet temperature sensor for detecting the outlet temperature of the unit heat exchanger, and the outlet pressure and the outlet temperature of the unit heat exchanger. And a unit heat exchanger overheat calculation unit configured to calculate an outlet superheat degree of the exchanger, wherein the control unit controls the rotation speed of the pump so that the calculated outlet superheat of the unit heat exchanger is a target superheat degree. Secondary refrigerant pump driven air conditioner. The method of claim 3, And a pump outlet pressure sensor for detecting the outlet pressure of the pump, and an inter-unit heat exchanger outlet pressure sensor for detecting the outlet pressure of the inter-unit heat exchanger, wherein the controller is configured such that the pump outlet pressure is greater than the outlet pressure of the inter-unit heat exchanger. Secondary refrigerant pump drive type air conditioner, characterized in that for controlling the rotation speed of the pump to be small. The method of claim 3, And an input current detector for detecting an input current of the pump, wherein the controller controls the rotation speed of the pump based on a result detected by the input current detector. group. The method of claim 3, And a refrigerant level sensor for detecting a liquid refrigerant level inside the receiver, wherein the controller is configured to suppress the inflow of gaseous refrigerant into the pump based on a detection result of the refrigerant level sensor. Secondary refrigerant pump driven air conditioner, characterized in that for controlling. The method of claim 3, And a high pressure detection sensor for detecting the discharge side pressure of the compressor, wherein the control unit controls the compression capacity of the compressor with the discharge side high pressure target value of the compressor. The method of claim 3, A first outdoor heat exchanger inlet temperature sensor and a first outdoor heat exchanger outlet temperature sensor for detecting a temperature of an inlet and an outlet of the first outdoor heat exchanger, and the first outdoor heat exchanger based on an inlet and an outlet temperature of the first outdoor heat exchanger; The first outdoor heat exchanger subcooling calculation unit for calculating the outlet side supercooling degree of the outdoor heat exchanger, and the compressor superheat calculation unit for calculating the superheat degree of the suction side refrigerant of the compressor, the control unit is the first When the outlet side supercooling degree of the outdoor heat exchanger exceeds a predetermined value and the suction side superheat degree of the compressor exceeds a certain value or more, the secondary refrigerant pump driven type is controlled to increase the opening degree of the outdoor expansion valve. Air conditioner. The method of claim 3, An indoor heat exchanger flow control valve disposed on one side of the indoor heat exchanger along a flow direction of the refrigerant, an intermediate temperature sensor for detecting an intermediate temperature of the indoor heat exchanger, and an outlet temperature of the indoor heat exchanger; And an indoor heat exchanger supercooling calculation unit configured to calculate an overcooling degree of the indoor heat exchanger based on an indoor heat exchanger outlet temperature sensor and an intermediate temperature of the indoor heat exchanger and an outlet temperature of the indoor heat exchanger. And a second refrigerant pump driven air conditioner controlling the indoor heat exchanger flow rate control valve such that the supercooling degree of the indoor heat exchanger is a target overcooling degree. The method of claim 14, And a unit heat exchanger outlet pressure sensor for detecting an outlet pressure of the unit heat exchanger, wherein the indoor heat exchanger and the coolant calculating unit are based on the outlet pressure of the unit heat exchanger and the outlet temperature of the indoor heat exchanger. A secondary refrigerant pump driven type air conditioner, characterized in that for calculating the outlet supercooling degree of the machine. The method of claim 15, The control unit controls the opened indoor heat exchanger flow rate control valve to open when the overcooling degree of the indoor heat exchanger of the stationary indoor unit calculated by the indoor heat exchanger and the cooling degree calculation unit exceeds a set value. A secondary refrigerant pump driven air conditioner, characterized in that the liquid refrigerant in the interior of the unit heat exchanger is recovered. The method according to any one of claims 1 to 16, A first four-way valve connected to the discharge side of the compressor to switch the flow path of the refrigerant of the first refrigerant circulation unit and a second four-way valve disposed on the discharge side of the pump to switch the flow path of the refrigerant of the second refrigerant circulation unit; Secondary refrigerant pump drive type air conditioner, characterized in that it further comprises. The method according to any one of claims 3 to 16, The compressor is composed of a plurality of secondary fuel pump drive type, characterized in that during the fuel oil operation of the compressor, the controller controls the rotational speed of the pump to correspond to the capacity of the compressor to be operated and then drive the compressor to be operated Air conditioner. The method according to any one of claims 3 to 16, The compressor includes an inverter compressor and a constant speed compressor, and the controller controls the rotation speed of the pump to correspond to the lowest frequency of the inverter compressor before controlling the inverter compressor to the lowest frequency for driving the constant speed compressor. And then controlling the inverter compressor to the lowest frequency.

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