KR102462874B1 - Air conditioner - Google Patents

Abstract

The air conditioner of this embodiment includes a compressor; a gas-liquid separator installed in the compressor suction passage; an oil separator installed in the compressor discharge passage; engine; a clutch for connecting and separating the engine and the compressor; an outdoor heat exchanger; an outdoor expansion valve connected to the outdoor heat exchanger; an indoor expansion valve connected to the outdoor expansion valve by a liquid pipe; an indoor heat exchanger connected to the indoor expansion valve; a cooling/heating switching valve connected to the compressor suction passage and the compressor discharge passage, connected to the outdoor heat exchanger and the outdoor heat exchanger connection passage, and connected to the indoor heat exchanger and the engine; an auxiliary heat exchanger having a coolant passage connected to the engine and a coolant line through which coolant introduced from the coolant line passes, and a coolant passage through which the coolant passes; a bypass passage connected to the liquid pipe; a bypass expansion valve connected to the bypass flow path; a hot gas bypass passage connecting the compressor discharge passage and the compressor suction passage; a hot gas bypass valve installed in the hot gas bypass passage; During heating operation, the hot gas bypass valve is opened and the clutch is controlled in the power cut-off mode, and the oil recovery standby mode in which the indoor expansion valve, the outdoor expansion valve and the bypass expansion valve are opened, and the clutch power transmission mode and a control unit that sequentially executes the oil recovery mode for controlling the heating and cooling switching valve to the cooling mode.

Description

Air conditioner and its operation method {Air conditioner}

The present invention relates to an air conditioner and a method for operating the same, and more particularly, to an air conditioner for compressing a refrigerant using a gas engine and a method for operating the same.

An air conditioner can cool or heat a room by a refrigeration cycle device using a refrigerant, and an example of such an air conditioner is a gas engine heat pump (GHP) air conditioner that cools and heats a room using a gas engine. .

An example of the GHP air conditioner is disclosed in Korean Patent Publication No. 10-0722091 B1 (notice on May 25, 2007), and in this air conditioner, a bypass passage is connected to a refrigerant passage that communicates an outdoor heat exchanger and an indoor heat exchanger. A refrigerant-cooling water heat exchanger and a sub-expansion valve capable of exchanging heat with the coolant that cooled the engine during the bypass passage and a sub-expansion valve are provided, and a main expansion valve for controlling the refrigerant flowing into the outdoor heat exchanger during heating is installed in the refrigerant passage do.

In the air conditioner as described above, when a shortage of oil occurs during heating operation, the four-way valve can be switched from the heating mode to the cooling mode to recover the oil to the gas-liquid separator. A sudden pressure fluctuation is generated in the gas-liquid separator due to the pressure difference, and the liquid refrigerant in the gas-liquid separator may be introduced into the compressor by such a large pressure fluctuation, and the reliability of the compressor may be reduced.

Republic of Korea Patent Publication No. 10-0722091 B1 (Announced on May 25, 2007)

An object of the present invention is to provide an air conditioner capable of minimizing suction of liquid refrigerant in a gas-liquid separator to a compressor when a mode of a heating/cooling switching valve for oil recovery is changed, and an operating method thereof.

An air conditioner according to an embodiment of the present invention includes: a compressor to which a compressor suction passage and a compressor discharge passage are connected; a gas-liquid separator installed in the compressor suction passage; an oil separator installed in the compressor discharge passage; engine; a clutch for connecting and separating the engine and the compressor; an outdoor heat exchanger; an outdoor expansion valve connected to the outdoor heat exchanger; an indoor expansion valve connected to the outdoor expansion valve through a liquid pipe, and an indoor heat exchanger connected to the indoor expansion valve; a cooling/heating switching valve connected to the compressor suction passage and the compressor discharge passage, connected to the outdoor heat exchanger and the outdoor heat exchanger connection passage, and connected to the indoor heat exchanger and the engine; an auxiliary heat exchanger having a coolant passage connected to the engine and a coolant line through which coolant introduced from the coolant line passes, and a coolant passage through which the coolant passes; a bypass passage connected to the liquid pipe; a bypass expansion valve connected to the bypass flow path; an auxiliary heat exchanger inlet passage connecting the bypass expansion valve and the refrigerant passage; an auxiliary heat exchanger outlet passage connecting the refrigerant passage and the compressor suction passage; a hot gas bypass passage connecting the compressor discharge passage and the compressor suction passage; a hot gas bypass valve installed in the hot gas bypass passage; includes a control unit.

During heating operation, the control unit opens the hot gas bypass valve, controls the clutch to power off mode, and operates the oil recovery standby mode in which the indoor expansion valve, the outdoor expansion valve and the bypass expansion valve are opened, and the clutch is powered. The oil recovery mode, which controls the transmission mode and controls the heating/cooling switch valve in the cooling mode, is sequentially performed.

When the oil in the oil separator is below a set level, the control unit may start the oil recovery standby mode. And, when the difference between the high pressure and the low pressure in the oil recovery standby mode is less than a set value, the control unit may start the oil recovery mode.

In the oil recovery standby mode, the control unit reduces the engine rotation speed to the set rotation speed and opens the hot gas bypass valve; and the second mode of opening the indoor expansion valve, the outdoor expansion valve, and the bypass expansion valve may be sequentially performed.

The control unit may close the hot gas bypass valve during the oil recovery mode.

After the oil recovery mode, the control unit controls the clutch to the power cut-off mode, opens the indoor expansion valve, the outdoor expansion valve, and the bypass expansion valve; It is possible to sequentially perform the heating operation mode to control the heating mode.

When the oil in the oil separator exceeds a set level during the oil recovery mode, the control unit may start the heating standby mode. And, if the difference between the high pressure and the low pressure in the middle of the heating standby mode is less than a set difference, the control unit may start the heating operation mode.

The controller may open the hot gas bypass valve in the heating standby mode. In addition, the control unit may close the hot gas bypass valve in the heating operation mode.

In a method of operating an air conditioner according to an embodiment of the present invention, during a heating operation of the air conditioner, the hot gas bypass valve is opened, the clutch is controlled to the power cutoff mode, and the indoor expansion valve and the outdoor expansion valve and opening the bypass expansion valve; It may include controlling the clutch in the power transmission mode and controlling the cooling/heating switching valve in the cooling mode.

A method of operating an air conditioner includes the steps of controlling a clutch in a power cut-off mode and opening an indoor expansion valve, an outdoor expansion valve, and a bypass expansion valve; The method may further include controlling the clutch in the power transmission mode and controlling the heating/cooling switching valve in the heating mode.

According to an embodiment of the present invention, the oil recovery standby mode is performed before the oil recovery mode, and the oil recovery mode is implemented in a state where the difference between the high and low pressures of the system is lowered. It is possible to minimize the inflow into the compressor by means of the compressor, there is an advantage that the reliability of the compressor is high.

In addition, in the oil recovery standby mode, since the difference between the high and low pressures is reduced step by step, it is possible to minimize the pressure fluctuation in the oil recovery standby mode and to minimize the sudden pressure fluctuation of the system.

In addition, since the hot gas bypass valve is closed in the middle of the oil recovery mode, the time of the oil recovery mode can be shortened, the oil can be quickly recovered, and the time of the heating operation mode can be maximized.

In addition, since the heating standby mode is checked before the heating operation mode and the heating operation mode is performed in a state where the difference between the high and low pressures of the system is lowered, it is possible to minimize the inflow of the liquid refrigerant in the gas-liquid separator into the compressor due to the pressure fluctuation in the gas-liquid separator. and high reliability of the compressor.

1 is a block diagram showing refrigerant flow during a cooling operation of an air conditioner according to an embodiment of the present invention;
2 is a block diagram showing refrigerant flow during a heating operation of the air conditioner according to an embodiment of the present invention;
3 is a configuration diagram when the air conditioner according to an embodiment of the present invention is in an oil recovery standby mode;
4 is a configuration diagram when the air conditioner according to an embodiment of the present invention is in a heating standby mode;
5 is a control block diagram of an air conditioner according to an embodiment of the present invention;
6 is a diagram showing changes in high pressure and low pressure when a heating operation, an oil recovery operation, and a heating operation are sequentially performed according to an embodiment of the present invention;
7 is a flowchart illustrating a method of operating an air conditioner according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with drawings.

1 is a block diagram illustrating refrigerant flow during a cooling operation of an air conditioner according to an embodiment of the present invention, and FIG. 2 is a block diagram illustrating a refrigerant flow during a heating operation of the air conditioner according to an embodiment of the present invention. 3 is a configuration diagram when the clutch of the air conditioner according to an embodiment of the present invention is in a power cutoff mode, and FIG. 4 is a control block diagram of the air conditioner according to an embodiment of the present invention.

It may include an outdoor unit O and a plurality of indoor units I1, I2, I3, and I4.

The outdoor unit O may be connected to the plurality of indoor units I1, I2, I3, and I4 through a liquid pipe L and an engine G.

The air conditioner includes an engine (1), a compressor (2), an outdoor heat exchanger (3), an indoor expansion valve (4), an indoor heat exchanger (5), a heating/cooling switching valve (6), and an outdoor expansion valve 12 , a clutch 17 , a hot gas bypass flow passage 18 , and a hot gas bypass valve 19 . The air conditioner includes an auxiliary heat exchanger 7 , a bypass flow passage 8 , a bypass valve 9 , and an auxiliary heat exchanger inlet flow passage 10 ; An auxiliary heat exchanger outlet flow path 11 may be further included.

The engine 1 may include a rotating shaft. The engine 1 may be driven to have a variable rotation speed. The engine 1 may change the rotation speed within the range of the minimum rotation speed and the maximum rotation speed.

A cooling water passage 1 ′ through which the coolant may pass may be formed in the engine 1 , and a coolant line 13 may be connected to the cooling water passage 1 ′. The air conditioner includes a radiator 14 connected to the cooling water line 13 and having a heat dissipation flow path through which the cooling water passes; It may further include a coolant valve 15 installed in the coolant line 13 to guide coolant heated in the engine 1 to the coolant flow path 71 or the radiator 14 of the auxiliary heat exchanger 7 .

The engine 1 may be connected to the auxiliary heat exchanger 7 , the radiator 14 , the coolant valve 15 , and the coolant pump 16 by the coolant line 13 .

The coolant line 13 includes an engine outlet water line 13A connecting the coolant flow passage 1 ′ of the engine 1 and the coolant valve 16 , and a coolant flow passage 71 between the coolant valve 15 and the auxiliary heat exchanger 7 . ), the auxiliary heat exchanger acquisition line 13B connecting (14) a radiator inlet line (13D), a radiator outlet line (13E) connecting the radiator (14) and the coolant pump (16), and a coolant pump (16) and a coolant flow path (1') of the engine (1) It may include an engine acquisition line (13F) connecting the.

The auxiliary heat exchanger 7 and the radiator 14 may be connected in parallel by a cooling water line 13 , and the cooling water valve 15 flows the cooling water flowing from the engine outlet line 13A to the auxiliary heat exchanger 7 . It can be guided to be or to be guided to flow to the radiator (14).

The cooling water valve 15 may be configured as a three-way valve, and is controlled in the auxiliary heat exchanger supply mode for guiding the cooling water to the auxiliary heat exchanger 7 by the control unit 100 to be described later or for guiding the cooling water to the radiator 14 . It can be controlled by radiator supply mode.

Meanwhile, the engine 1 may be connected to or separated from the compressor 2 by the clutch 17 . The clutch 17 may be connected to at least one of a rotation shaft of the engine 1 and a drive shaft of the compressor 2 and a power transmission member such as a pulley or a belt.

As shown in FIGS. 1 and 2 , the clutch 17 can transmit the rotational force of the rotating shaft between the rotating shaft of the engine 1 and the driving shaft of the compressor 2 to the driving shaft of the compressor 2 in the power transmission mode. have. When the clutch 17 is turned on, the clutch 17 may be in a power transmission mode, and may be driven by the rotation shaft of the engine 1 to drive the drive shaft of the compressor 2 .

As shown in FIGS. 3 and 4 , the clutch 17 transmits the rotational force of the rotating shaft between the rotating shaft of the engine 1 and the driving shaft of the compressor 2 to the driving shaft of the compressor 2 in the power off mode. it may not be When the clutch 17 is off, the clutch 17 may be in a power cut-off mode, and even if the rotation shaft of the engine 1 rotates, the drive shaft of the compressor 2 may be stopped.

A compressor suction passage 21 and a compressor discharge passage 22 may be connected to the compressor 2 , and the compressor 2 may be driven by the engine 1 to compress the refrigerant.

When the compressor 2 is driven according to the driving of the engine 1 , the refrigerant in the compressor suction passage 21 may be sucked into the compressor 2 and compressed in the compressor 2 , and compressed in the compressor 2 . The refrigerant may be discharged through the compressor discharge passage 22 .

The compressor 2 may be composed of a rotary compression mechanism having a cylinder and a piston or a scroll compression mechanism having a fixed scroll and an orbiting scroll, and may include a drive shaft driven by the compressor 1 . The drive shaft of the compressor 2 may be directly connected to the clutch 17 or connected to a power transmission member, and may be configured as a variable capacity compression mechanism in which the compression capacity can be varied when the rotation speed of the engine 1 is changed.

The gas-liquid separator 23 may be installed in the compressor suction passage 21 . Among the gas-phase refrigerant and liquid refrigerant flowing from the air-conditioning switching valve 6 , the liquid refrigerant may be contained in the gas-liquid separator 23 , and the gaseous refrigerant may be sucked from the gas-liquid separator 23 to the compressor 2 . The gas-liquid separator 23 may be connected to the compressor 2 or the compressor suction passage 21 through an oil return pipe 25 .

The oil separator 24 may further include an oil separator 24 mounted on the compressor discharge passage 22 . The refrigerant and oil discharged from the compressor 2 may be separated by the oil separator 24 , and the oil separated from the refrigerant in the oil separator 24 is sucked into the gas-liquid separator 23 or the compressor through the oil return pipe 26 . After flowing into the flow path 21 , it may be recovered by the compressor 2 .

The oil separator 24 may be equipped with an oil sensor 27 capable of detecting the amount of oil. The oil sensor 27 may be an oil level sensor capable of detecting the level (height) of oil in the oil separator 24 .

The outdoor heat exchanger 3 may be connected to the cooling/heating switching valve 6 and the outdoor heat exchanger connection passage 31 . The outdoor heat exchanger 3 exchanges heat with outdoor air and a refrigerant, and the outdoor heat exchanger 3 may include a refrigerant tube through which the refrigerant passes.

The outdoor heat exchanger 3 may be connected to the outdoor expansion valve 12 . The outdoor heat exchanger (3) may be connected to the outdoor expansion valve (12) and a connecting tube (32).

The air conditioner may further include an outdoor fan 33 for blowing outdoor air to the outdoor heat exchanger 3 .

The indoor expansion valve 4 may be connected to the outdoor expansion valve 12 by a liquid pipe (L). The indoor expansion valve 4 may constitute an indoor unit together with the indoor heat exchanger 5 . The air conditioner may further include an indoor fan 52 for flowing indoor air to the indoor heat exchanger 5 .

The present embodiment may include a plurality of indoor units, and each of the plurality of indoor units I1, I2, I3, and I4 includes an indoor expansion valve 4 and an indoor heat exchanger 5 connected to the indoor expansion valve 4 . ) may be included. Each of the plurality of indoor units I1 , I2 , I3 , and I4 may include an indoor expansion valve 4 , an indoor heat exchanger 5 , and an indoor fan 52 .

The cooling/heating switching valve 6 is connected to each of the compressor suction flow path 21 and the compressor discharge flow path 22, connected to the outdoor heat exchanger 3 and the outdoor heat exchanger connection flow path 31, and a plurality of indoor units I1 and I2. It can be connected to (I3) (I4) and the organ (G).

The heating/cooling switching valve 6 may be a four-way valve controlled in a cooling mode or a heating mode.

In the cooling mode, the cooling/heating switching valve 6 guides the refrigerant in the compressor discharge passage 22 to the outdoor heat exchanger connection passage 31 and also guides the refrigerant in the engine G to the compressor suction passage 21. have.

The cooling/heating switching valve 6 can guide the refrigerant in the compressor discharge passage 22 to the engine G in the heating mode, and guide the refrigerant in the outdoor heat exchanger connection passage 31 to the compressor suction passage 21. can

The auxiliary heat exchanger 7 may be connected to the engine 1 and the coolant line 13 . The auxiliary heat exchanger 7 may be a refrigerant-cooling water heat exchanger that exchanges heat between the refrigerant and the cooling water. The auxiliary heat exchanger 7 may be a coolant heat radiation heat exchanger that heats the coolant flowing in the engine 1 with a coolant to radiate heat. In addition, the auxiliary heat exchanger 7 may be an evaporator that evaporates the refrigerant expanded by the bypass expansion valve 9 after being condensed in the outdoor heat exchanger 3 during the cooling operation.

A cooling water passage 71 through which the cooling water introduced from the cooling water line 13 passes and a refrigerant passage 72 through which the refrigerant passes may be formed in the auxiliary heat exchanger 7 .

The auxiliary heat exchanger 7 may be a bypass heat exchanger in which the refrigerant condensed in the outdoor heat exchanger 3 passes while bypassing the indoor expansion valve 4 and the indoor heat exchanger 5 during the cooling operation.

The bypass flow path 8 may be connected between the outdoor heat exchanger 3 and the indoor expansion valve 4 of the liquid pipe L. The bypass flow path 8 may be connected between the outdoor expansion valve 12 and the indoor expansion valve 4 of the liquid pipe L.

The bypass expansion valve 9 may be connected to the bypass flow passage 8 .

The auxiliary heat exchanger inlet passage 10 may connect the bypass expansion valve 9 and the refrigerant passage 72 .

The auxiliary heat exchanger outlet passage 11 may connect the refrigerant passage 72 and the compressor suction passage 21 . The auxiliary heat exchanger outlet passage 11 may be connected between the air-conditioning switching valve 6 and the gas-liquid separator 23 among the compressor suction passages 21 .

The hot gas bypass passage 18 may connect the compressor discharge passage 22 and the compressor suction passage 21 . One end of the hot gas bypass flow path 18 may be connected between the oil separator 24 of the compressor discharge flow path 22 and the heating/cooling switching valve 6 . The other end of the hot gas bypass flow path 18 may be connected between the air-conditioning switching valve 6 and the gas-liquid separator 23 of the compressor suction flow path 21 .

The hot gas bypass valve 19 may be installed in the hot gas bypass passage 18 . When the hot gas bypass valve 19 is opened, the high-temperature and high-pressure gaseous refrigerant that has passed through the oil separator 24 is transferred to the outdoor heat exchanger 3, the outdoor expansion valve 12, the indoor expansion valve 4, and the indoor heat exchanger. After bypassing (5), it may flow to the gas-liquid separator 23 .

Engine (1), compressor (2), outdoor heat exchanger (3), air-conditioning switching valve (6), auxiliary heat exchanger (7), bypass flow passage (8), and bypass valve (9) and an auxiliary heat exchanger inlet passage 10, an auxiliary heat exchanger outlet passage 11, an outdoor expansion valve 12, a cooling water line 13, a radiator 14, a cooling water valve 15, The cooling water pump 16 , the hot gas bypass passage 18 , and the hot gas bypass valve 19 may all be installed in the outdoor unit O .

The air conditioner may include a control unit 100 . The air conditioner may include a low pressure sensor 102 that detects the pressure of the compressor suction passage 21 and transmits a signal according to the sensed pressure to the controller 100 . The air conditioner may include a high pressure sensor 104 that senses the pressure of the compressor discharge passage 22 and transmits a signal according to the sensed pressure to the controller 100 .

The control unit 100 may be an outdoor unit control unit that controls the outdoor unit O, and may include an engine 1, a heating/cooling switching valve 6, a bypass expansion valve 9, an outdoor expansion valve 12, and a cooling water valve 15. It is possible to control the clutch 17 , the hot gas bypass valve 19 and the outdoor fan 33 .

The control unit 100 may control the cooling/heating switching valve 6 according to the cooling operation and the heating operation of the air conditioner.

If the condition for starting the oil recovery operation is in the middle of the heating operation, the control unit 100 may stop the heating operation in progress and perform the oil recovery operation. You can return to driving. The controller 100 may control the heating/cooling switching valve 6 so that the air conditioner operates like a cooling operation during the oil recovery operation. The control unit 100 may control the clutch 17 before and after the oil recovery operation. The controller 100 may control the indoor expansion valve 4, the bypass expansion valve 9, and the outdoor expansion valve 12 before and after the oil recovery operation.

Hereinafter, the heating operation will be described as a heating operation mode (D), and the oil recovery operation will be described as an oil recovery mode (B).

6 is a diagram illustrating changes in high pressure and low pressure when a heating operation, an oil recovery operation, and a heating operation are sequentially performed according to an embodiment of the present invention, and FIG. 7 is a diagram of an air conditioner according to an embodiment of the present invention. It is a flowchart showing the driving method.

The controller 100 of this embodiment may control the air conditioner in an oil recovery standby mode (A), an oil recovery mode (B), a heating standby mode (C), and a heating operation mode (D). The controller 100 may control the air conditioner in the order of an oil recovery standby mode (A), an oil recovery mode (B), a heating standby mode (C), and a heating operation mode (D), and a heating operation mode (D) After that, the oil recovery standby mode (A) can be resumed again.

The control unit 100 controls the engine 1 according to the load during the control cycle sequentially in the order of the oil recovery standby mode (A), the oil recovery mode (B), the heating standby mode (C), and the heating operation mode (D). It is possible to drive at the variable rotation speed RO which is variable, and it is possible to drive the engine 1 at the set rotation speed R1 or the minimum rotation speed R2.

The set number of revolutions R1 may be a higher number of revolutions than the minimum number of revolutions R2. The set rotation speed R1 may be a lower rotation speed than the variable rotation speed RO of the heating operation mode (D).

The control unit 100 operates the clutch 17 in the power cut-off mode or power during the control cycle sequentially in the order of the oil recovery standby mode (A), the oil recovery mode (B), the heating standby mode (C), and the heating operation mode (D). It is possible to control in transfer mode.

The control unit 100 controls the expansion valves 4, 9 and 12 during a control cycle sequentially in the order of the oil recovery standby mode (A), the oil recovery mode (B), the heating standby mode (C), and the heating operation mode (D). .

The control unit 100 operates the hot gas bypass valve 19 during one control cycle sequentially in the order of the oil recovery standby mode (A), the oil recovery mode (B), the heating standby mode (C), and the heating operation mode (D). It is possible to control in open mode or closed mode.

The control unit 100 operates the cooling/heating switching valve 6 during one control cycle in the order of the oil recovery standby mode (A), the oil recovery mode (B), the heating standby mode (C), and the heating operation mode (D) in the cooling mode. It is possible to control in heating mode.

Hereinafter, the oil recovery standby mode (A) will be described first.

The oil recovery standby mode (A) may be started while the air conditioner is in the heating operation mode (D). The oil recovery standby mode (A) may be started if the oil in the compressor (2) is insufficient in the middle of the heating operation mode (D), that is, an oil recovery condition. The oil recovery condition may be a case where the oil in the oil separator 24 is below a set level, and the controller 100 waits for oil recovery if the oil in the oil separator 24 is below the oil recovery level during the heating operation mode (D). Mode (A) can be initiated.

The oil sensor 26 may detect the level of oil in the oil separator 24 and transmit a signal according to the sensed value to the control unit 100 , and the control unit 100 determines that the oil level detected by the oil sensor 26 is the oil level. If it is below the recovery level, the heating operation mode (D) may be stopped and the oil recovery standby mode (A) may be started.

The oil recovery standby mode (A) is a mode in which the system as a whole is equalized so that the high and low pressures of the system become close to each other quickly, and may be a kind of equalization mode.

In the oil recovery standby mode (A), the hot gas bypass valve 19 is opened, the clutch 17 is controlled in the power cut-off mode, and the indoor expansion valve 4, the outdoor expansion valve 12 and the bypass It may be a mode for opening the expansion valve (9).

In the oil recovery standby mode (A), the control unit 100 opens the hot gas bypass valve 19, controls the clutch 17 to power off mode, and also includes an indoor expansion valve 4 and an outdoor expansion valve. (12) and the bypass expansion valve (9) can be opened.

Here, the indoor expansion valve 4 and the outdoor expansion valve 12 are opened to open the indoor expansion valve 4, the outdoor expansion valve 12, and the bypass expansion valve 9 in the oil recovery standby mode (A). and the bypass expansion valve 9 to the maximum opening degree, and the control unit 100 controls the expansion valves 4, 9 and 12, that is, the indoor expansion valve 4 and the outdoor expansion valve ( 12) and the bypass expansion valve 9 can be controlled in the open mode.

In addition, in the oil recovery standby mode (A), the control unit 100 may drive the engine 1 at the set rotation speed R1 or the minimum rotation speed R2 without stopping the engine 1 .

The control unit 100 opens the hot gas bypass valve 19 and controls the clutch 17 in the power cut-off mode during the oil recovery condition, and controls the indoor expansion valve 4, the outdoor expansion valve 12 and the bypass mode. Of course, it is possible to simultaneously open the pass expansion valve 9, and it is also possible that a part of the control is performed with a time difference.

In the oil recovery standby mode (A), the control unit 100 may sequentially execute the first mode (A1) and the second mode (A2).

In the first mode A1 , the controller 100 may control the engine 1 to the set rotation speed R1 and open the hot gas bypass valve 19 .

The engine 1, which was being driven at the variable rotational speed (RO) during the heating operation mode (D), does not stop in the oil recovery standby mode (A) and continues to be driven, but is set lower than before the oil recovery standby mode (A) is started It may be driven at the rotation speed R1.

In the first mode (A1) of the oil recovery standby mode (A), when the rotation speed of the engine 1 is lowered to the set rotation speed R1 and the hot gas bypass valve 19 is opened, the high pressure of the system is returned to the oil recovery It may be gradually lowered than before in the standby mode (A), the low pressure of the system may be gradually higher than before in the oil recovery standby mode (A), and the difference between the high and low pressures of the system may be gradually reduced as time passes.

In the second mode (A2), the control unit 100 reduces the rotation speed of the engine 1 to the minimum rotation speed R2, controls the clutch 17 to the power cut-off mode, and the expansion valves 4 and 9 (12) That is, the indoor expansion valve 4, the outdoor expansion valve 12, and the bypass expansion valve 9 can be opened in the open mode.

The second mode (A2) of the oil recovery standby mode (A) can be started after the first mode (A1) has been executed for a set time, and can also be started when the difference between the high and low pressures of the system is within the set range. do.

In the second mode (A2) of the oil recovery standby mode (A), when the clutch 17 is controlled to the power cut-off mode, the compressor 2 is gradually decelerated, and the expansion valves 4, 9 and 12, that is, When the indoor expansion valve 4, the outdoor expansion valve 12 and the bypass expansion valve 9 are opened in the open mode, the high pressure and the low pressure of the system can be approached quickly.

After reducing the high and low pressure difference in the first mode (A1), the control unit 100 can secondarily reduce the high and low pressure difference in the second mode (A2), and the entire period of the oil recovery standby mode (A) While the pressure fluctuation inside the system is not large during the period, it is possible to more stably reduce the high-low pressure difference in the system.

In the middle of the second mode A2, the control unit 100 controls the expansion valves 4, 9 and 12, that is, the indoor expansion valve 4, the outdoor expansion valve 12, and the bypass expansion valve 9. Like the heating operation mode (D), it can be switched to the variable opening mode.

Hereinafter, the oil recovery mode (B) will be described.

The oil recovery mode (B) is a mode implemented after the oil recovery standby mode (A) is executed, and may be started in a state in which the system is sufficiently flattened. The oil recovery mode (B) may be started when the difference between the high pressure and the low pressure in the oil recovery standby mode (A) is less than a set value.

When the difference between the high pressure sensed by the high pressure sensor 104 and the low pressure sensed by the low pressure sensor 102 is less than a set value, the control unit 100 may start the oil recovery mode (B).

The oil recovery mode (B) may be a mode in which the clutch 17 is controlled in the power transmission mode and the heating/cooling switching valve 6 is controlled in the cooling mode.

When the high and low pressures are the same or the difference between the high and low pressures is less than the set value, the system is in a sufficiently flattened state. The pressure in the gas-liquid separator 23 does not fluctuate significantly. That is, even when the air-conditioning switching valve 6 is switched from the heating mode to the cooling mode, the liquid refrigerant in the gas-liquid separator 23 does not flow into the compressor suction passage 21 and may remain in the gas-liquid separator 23, and the compressor 2 ) can be improved.

The control unit 100 may drive the engine 1 at a set rotation speed R1 or a variable rotation speed RO higher than the minimum rotation speed R2 in the oil recovery mode (B). The control unit 100 may drive the engine 1 at a variable rotation speed RO higher than the set rotation speed R1 in the middle of the oil recovery mode B.

The control unit 100 may close the hot gas bypass valve 19 in the middle of the oil recovery mode (B). The oil recovery mode (B) includes a third mode (B1) in which oil is recovered in a state in which the hot gas bypass valve 19 is open, and a third mode in which oil is recovered in a state in which the hot gas bypass valve 19 is closed. Four modes (B2) may be included.

The third mode B1 may be a mode for recovering oil from the entire system including the hot gas bypass flow path 18 , and the fourth mode B2 may be a mode for recovering the entire system including the hot gas bypass flow path 18 . It may be a mode for recovering oil.

At the start of the oil recovery mode (B), the hot gas bypass valve 19 is in an open state, and in the middle of the oil recovery mode (B), some of the refrigerant in the compressor discharge flow passage 22 is part of the hot gas bypass passage 18 ) and the hot gas bypass valve 19 , the oil in the hot gas bypass passage 18 may be pressurized to the compressor suction passage 21 .

When the oil in the hot gas bypass flow passage 18 is sufficiently recovered, the controller 100 controls the hot gas bypass valve 19 so that the oil in the outdoor heat exchanger 3 or the indoor heat exchanger 5 can be quickly recovered. can be closed. In the case of the fourth mode (B2), a larger amount of refrigerant can pass through the outdoor heat exchanger (3) or the indoor heat exchanger (5) than in the case of the third mode (B1), and the outdoor heat exchanger (3) or indoor heat exchange The oil in the group 5 can be recovered more quickly in the fourth mode (B2).

The control unit 100 may close the hot gas bypass valve 19 when a set time (eg, 2 minutes) has elapsed from the time when the oil recovery mode B is started.

When the oil in the system is sufficiently recovered by the oil recovery mode (B), the control unit 100 may stop the oil recovery mode (B) and start the heating standby mode (C).

The control unit 100 may start the heating standby mode (C) when the oil in the oil separator 24 is above the heating return level in the middle of the oil recovery mode (B). The heating return level may be a level set higher than the oil recovery level.

In the oil recovery mode (B), since the air conditioner operates as in the cooling mode, the high and low pressure difference of the system may be large, and the control unit 100 controls the system before returning to the heating operation mode (D) again. In order to lower the high and low pressure difference again, a heating standby mode (C) may be performed.

Hereinafter, the heating standby mode (C) will be described.

In the heating standby mode (C), after the oil recovery mode (B), the clutch 17 is controlled in the power cut-off mode and the expansion valves 4, 9 and 12, that is, the indoor expansion valve 4, and the outdoor expansion It may be a mode for opening the valve 12 and the bypass expansion valve 9 .

In the heating standby mode (C), the controller 100 may drive the engine 1 at the lowest rotational speed R2. In addition, the control unit 100 may open the hot gas bypass valve 19 in the heating standby mode.

In the heating standby mode (C) as described above, the air conditioner may reduce the high and low pressure difference of the system, as in the oil recovery standby mode (A).

The control unit 100 controls the expansion valves 4, 9 and 12, that is, the indoor expansion valve 4, the outdoor expansion valve 12, and the bypass expansion valve 9, during the heating standby mode (C). The opening can be switched to variable mode.

Hereinafter, the heating operation mode (D) will be described.

The heating operation mode (D) is a mode implemented after the heating standby mode (C) is implemented, and may be started in a state in which the system is sufficiently flattened. The heating operation mode (D) may be started when the difference between the high pressure and the low pressure in the heating standby mode (C) is less than a set value.

When the difference between the high pressure sensed by the high pressure sensor 104 and the low pressure sensed by the low pressure sensor 102 is less than a set value, the control unit 100 may start the heating operation mode (D).

The heating operation mode (D) may be a mode in which the controller 100 controls the clutch 18 in the power transmission mode and controls the heating/cooling switching valve 6 in the heating mode.

In the heating operation mode (D), the control unit 100 may drive the engine 1 at a variable rotation speed RO higher than the minimum rotation speed R2.

The control unit 100 may close the hot gas bypass valve 19 in the heating operation mode (D).

As described above, when the high pressure and the low pressure are the same by the heating standby mode (C) or the difference between the high and low pressure is less than the set value, the system is in a sufficiently flattened state, and in this way, the heating operation mode ( When D) is started and the heating/cooling switching valve 6 is switched from the cooling mode to the heating mode, the pressure in the gas-liquid separator 23 does not change significantly. That is, even when the cooling/heating switching valve 6 is switched from the cooling mode to the heating mode, the liquid refrigerant in the gas-liquid separator 23 does not flow into the compressor suction passage 21 and may remain in the gas-liquid separator 23, and the compressor 2 ) can be improved.

7 is a flowchart illustrating a method of operating an air conditioner according to an embodiment of the present invention.

In the operating method of the air conditioner according to the present embodiment, during the heating operation of the air conditioner, the hot gas bypass valve 9 is opened, the clutch 17 is controlled to the power cutoff mode, and the indoor expansion valve 4 ), and the oil recovery standby step (S1) (S2) (S3) of opening the outdoor expansion valve 12 and the bypass expansion valve 9 may be included.

As described above, the oil recovery waiting steps (S1) (S2) (S3) (S4) can be carried out if the oil level detected by the oil sensor 26 during the heating operation mode (D) is below the oil recovery level. have.

The oil recovery standby steps (S1), (S2) and (S3) are a first process of controlling the rotation speed of the engine 1 to a set rotation speed R1 and opening the hot gas bypass valve 19, and the first process On the way, the rotation speed of the engine 1 is reduced to the minimum rotation speed R2, the clutch 17 is controlled in the power cut-off mode, and the expansion valves 4, 9 and 12, that is, the , a second process of opening the outdoor expansion valve 12 and the bypass expansion valve 9 may be included.

And, the operating method of the air conditioner may include oil recovery operation steps (S4) and (S5) of controlling the clutch 17 in the power transmission mode and controlling the heating/cooling switching valve 6 in the cooling mode.

In the oil recovery operation steps (S4) and (S5) as described above, when the difference (P) between the high pressure detected by the high pressure sensor 104 and the low pressure detected by the low pressure sensor 102 is less than the set value, the oil recovery mode (B) can be initiated.

In the oil recovery operation steps S4 and S5, the engine 1 may be driven at a rotation speed higher than the minimum rotation speed R2 or may be driven at a rotation speed higher than the set rotation speed R1.

The air conditioner may close the hot gas bypass valve 19 during the oil recovery operation steps S4 and S5. The oil recovery operation steps (S4) and (S5) are a third process in which oil is recovered in a state in which the hot gas bypass valve 19 is open, and oil is recovered in a state in which the hot gas bypass valve 19 is closed. A fourth mode may be included.

In the oil recovery operation steps (S4) and (S5), the hot gas bypass valve 19 may be closed when a set time (eg, 2 minutes) has elapsed from the starting point.

The operation method of the air conditioner is to control the clutch in the power cut-off mode, and the expansion valves 4, 9 and 12, that is, the indoor expansion valve 4, the outdoor expansion valve 12, and the bypass expansion valve 9 ) may further include a heating standby step (S6) (S7) to open.

The heating standby steps (S6) and (S7) may be initiated if the oil in the oil separator 24 is above the heating return level during the oil recovery step (S5).

In the heating standby step (S6) and (S7), after the oil recovery step (S5), the clutch 17 is controlled in the power cut-off mode, and the indoor expansion valve 4, the outdoor expansion valve 12, and the bypass expansion valve are controlled. (9) may be a mode to open.

In the heating standby step ( S6 ) ( S7 ), the engine 1 may be driven at the lowest rotational speed R2 , and the hot gas bypass valve 19 may be opened.

In the heating standby steps (S6) and (S7), the expansion valves 4, 9 and 12, that is, the indoor expansion valve 4, the outdoor expansion valve 12, and the bypass expansion valve 9 are opened in the middle. It can be switched to variable mode.

The operating method of the air conditioner may further include heating operation steps (S8) and (S9) of controlling the clutch 17 in the power transmission mode and controlling the heating/cooling switching valve 6 in the heating mode.

The heating operation step (S8) (S9) is a step carried out after the heating standby step (S6) (S7), and the high pressure and low pressure sensor 102 detected by the high pressure sensor 104 during the heating standby step (S6) (S7) ), when the detected low pressure difference (P) is less than the set value, it may be initiated.

The heating operation step (S8) (S9) may drive the engine 1 at a rotation speed higher than the minimum rotation speed R2. The heating operation step (S8) (S9) may close the hot gas bypass valve (19).

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments.

The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

1: Engine 2: Compressor
3: Outdoor heat exchanger 4: Indoor expansion valve
5: Indoor heat exchanger 6: Heating and cooling switching valve
7: Auxiliary heat exchanger 9: Bypass expansion valve
10: auxiliary heat exchanger inlet passage 11: auxiliary heat exchanger outlet passage
12: outdoor expansion valve 17: clutch
19: hot gas bypass valve 27: oil sensor
100: control unit 102: low pressure sensor
104: high pressure sensor

Claims (9)

a compressor to which the compressor suction passage and the compressor discharge passage are connected;
a gas-liquid separator installed in the compressor suction passage;
an oil separator installed in the compressor discharge passage;
engine;
a clutch for connecting and disconnecting the engine and the compressor;
an outdoor heat exchanger;
an outdoor expansion valve connected to the outdoor heat exchanger;
an indoor expansion valve connected to the outdoor expansion valve by a liquid pipe;
an indoor heat exchanger connected to the indoor expansion valve;
a cooling/heating switching valve connected to the compressor suction passage and the compressor discharge passage, connected to the outdoor heat exchanger and the outdoor heat exchanger connection passage, and connected to the indoor heat exchanger and an engine;
an auxiliary heat exchanger connected to the engine and a coolant line and having a coolant passage through which the coolant introduced from the coolant line passes, and a coolant passage through which the coolant passes;
a bypass passage connected to the liquid pipe;
a bypass expansion valve connected to the bypass flow passage;
an auxiliary heat exchanger inlet passage connecting the bypass expansion valve and the refrigerant passage;
an auxiliary heat exchanger outlet passage connecting the refrigerant passage and the compressor suction passage;
a hot gas bypass passage having one end connected between the oil separator and the air-conditioning switching valve in the compressor discharge passage, and the other end connected between the air-conditioning switching valve and the gas-liquid separator in the compressor suction passage;
a hot gas bypass valve installed in the hot gas bypass passage;
an oil recovery standby mode in which the hot gas bypass valve is opened during heating operation, the clutch is controlled in a power cutoff mode, and the indoor expansion valve, the outdoor expansion valve, and the bypass expansion valve are opened; and a control unit for sequentially executing an oil recovery mode for controlling the air conditioner in the power transmission mode and controlling the heating and cooling switching valve in the cooling mode. The method of claim 1,
When the oil in the oil separator is below a set level, the control unit starts the oil recovery standby mode,
The control unit recovers oil when the difference between the high pressure sensed by the high pressure sensor for detecting the pressure of the compressor discharge channel and the low pressure sensed by the low pressure sensor for detecting the pressure of the compressor suction channel during the oil recovery standby mode is less than a set value The air conditioner that initiates the mode. The method of claim 1,
The control unit, in the oil recovery standby mode,
a first mode for reducing the engine rotation speed to a set rotation speed and opening the hot gas bypass valve;
An air conditioner that reduces the engine rotation speed to a minimum rotation speed, controls the clutch in a power cut-off mode, and sequentially performs a second mode of opening the indoor expansion valve, the outdoor expansion valve, and the bypass expansion valve . The method of claim 1,
The control unit closes the hot gas bypass valve during the oil recovery mode. The method of claim 1,
After the oil recovery mode, the control unit controls the clutch in a power cut-off mode and opens the indoor expansion valve, the outdoor expansion valve, and the bypass expansion valve in a heating standby mode;
An air conditioner that sequentially executes a heating operation mode in which the clutch is controlled in a power transmission mode and the heating/cooling switching valve is controlled in a heating mode. 6. The method of claim 5,
the control unit
If the oil in the oil separator exceeds the set level during the oil recovery mode, the heating standby mode is started,
If the difference between the high pressure sensed by the high pressure sensor for detecting the pressure of the compressor discharge flow path and the low pressure sensor for detecting the pressure of the compressor suction flow path during the heating standby mode is less than the set difference, the heating operation mode An air conditioner disclosed. 6. The method of claim 5,
The control unit is
In the heating standby mode, the hot gas bypass valve is opened,
In the heating operation mode, the air conditioner closes the hot gas bypass valve. a compressor to which the compressor suction passage and the compressor discharge passage are connected;
a gas-liquid separator installed in the compressor suction passage;
an oil separator installed in the compressor discharge passage;
engine;
a clutch for connecting and disconnecting the engine and the compressor;
an outdoor heat exchanger;
an outdoor expansion valve connected to the outdoor heat exchanger;
an indoor expansion valve connected to the outdoor expansion valve by a liquid pipe;
an indoor heat exchanger connected to the indoor expansion valve;
a cooling/heating switching valve connected to the compressor suction passage and the compressor discharge passage, connected to the outdoor heat exchanger and the outdoor heat exchanger connection passage, and connected to the indoor heat exchanger and an engine;
an auxiliary heat exchanger connected to the engine by a coolant line and having a coolant passage through which the coolant introduced from the coolant line passes, and a coolant passage through which the coolant passes;
a bypass passage connected to the liquid pipe;
a bypass expansion valve connected to the bypass flow path;
an auxiliary heat exchanger inlet passage connecting the bypass expansion valve and the refrigerant passage;
an auxiliary heat exchanger outlet passage connecting the refrigerant passage and the compressor suction passage;
a hot gas bypass passage having one end connected between the oil separator and the air-conditioning switching valve in the compressor discharge passage, and the other end connected between the air-conditioning switching valve and the gas-liquid separator in the compressor suction passage;
A method of operating an air conditioner including a hot gas bypass valve installed in the hot gas bypass passage, the method comprising:
During the heating operation of the air conditioner,
opening the hot gas bypass valve, controlling the clutch to power off mode, and opening the indoor expansion valve, the outdoor expansion valve, and the bypass expansion valve;
and controlling the clutch in a power transmission mode and controlling the cooling/heating switching valve in a cooling mode. 9. The method of claim 8,
After controlling the clutch in the power transmission mode and controlling the cooling/heating switching valve in the cooling mode,
controlling the clutch in a power cut-off mode and opening the indoor expansion valve, the outdoor expansion valve, and the bypass expansion valve;
and controlling the clutch in a power transmission mode and controlling the heating/cooling switching valve in a heating mode.

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