JP6634590B2 - Air conditioner - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an outdoor unit of an air conditioner provided with a non-power-driven compressor driven by an engine and a power-driven compressor driven by electric power.

  When the gas heat pump is partially loaded, the heat efficiency of the gas engine is reduced, and the operation efficiency of the air conditioner is reduced. In order to avoid this, a compressor driven by an electric motor with a smaller displacement volume than a compressor driven by a gas engine is installed in parallel, and when a partial load is applied, the compressor is driven mainly by an electric motor driven compressor. It has been proposed that a so-called hybrid air conditioner with a gas engine-driven compressor and an electric motor-driven compressor that operates mainly on a gas engine and that enables high-efficiency operation according to the required load size. (For example, see Patent Document 1).

  Compared to an air conditioner in which all compressors are driven by a power motor, the hybrid air conditioner has an advantage that a basic electricity charge can be set lower or energy risks are dispersed. Taking advantage of these advantages, the gas engine drive and electric motor are controlled by the combination of parameters such as the processing load capacity of the gas engine drive compressor, the processing load capacity of the electric motor drive compressor, and the upper limit of the power consumption of the electric motor drive compressor. There has been proposed a technique for controlling the operation ratio of a driven compressor to maintain the total efficiency at a high level and level the power consumption. (See Patent Document 2)

JP 2003-56931 A JP 2007-187342 A

  The air conditioner disclosed in Patent Literature 1 discloses a technology that enables high-efficiency operation according to a required load.

  However, Patent Document 1 discloses an invention in which a compressor using a gas engine as a driving source and a compressor using an electric motor as a driving source coexist to maintain a high total efficiency. No leveling of power use is indicated.

  In the air conditioner disclosed in Patent Literature 2, a technology for controlling the operation ratio of a gas engine drive compressor and an electric motor drive compressor to maintain the total efficiency at a high level and level the power use is disclosed. I have. For example, when the air-conditioning load is high, such as during the daytime in summer or early in the morning in winter, high performance is required for the air-conditioning apparatus. When no control is performed, the power consumption becomes extremely large. In such a case, according to the technology disclosed in Patent Literature 2, in order to equalize the power usage, control is performed to increase the operating ratio of the gas engine driven compressor and decrease the operating ratio of the electric motor driven compressor. However, in such a case, since the gas engine driven compressor is operated at a high rotation speed and the electric motor compressor is operated at a low rotation speed, the amounts of refrigerant compressed by the respective compressors are largely biased. As a result, the oil circulating in the circuit together with the refrigerant is biased back toward the engine-driven compressor that is operating at a high speed. The amount of oil in the driven electric motor driven compressor is reduced, which causes a problem that the compressor is damaged due to insufficient oil.

  However, the technology disclosed in Patent Literature 2 is an invention that maintains the efficiency to a high degree and level power use, and a solution to the problem caused by leveling power use is not shown. Not in.

  An object of the present invention is to provide a highly reliable air conditioner that eliminates unevenness in the amount of oil even when a compressor having a different driving system and a different capacity is driven in combination.

In order to solve the above problems, in the air conditioner of the present invention, a first compressor using a gas engine connected in parallel in a refrigeration cycle as a drive source and a second compressor using an electric motor as a drive source in the air conditioning apparatus performs air conditioning by circulating the refrigerant by the machine, the first and second oil separator for separating the first and second compressors each refrigerant and lubricating oil to the discharge side of the first The first oil return pipe for guiding the lubricating oil separated by the oil separator to the suction side of the first compressor, and the lubricating oil separated by the second oil separator to the suction side of the second compressor. A second oil return pipe for guiding, the first oil return pipe has a first electromagnetic valve and a first flow path resistance, and a second electromagnetic valve and a first flow path resistance A second flow path resistance having a lower resistance than the second flow path resistance is provided in parallel via the branch part. , On the basis of a signal from the second oil level detecting means provided in the compressor, a control means for controlling the opening and closing of the first solenoid valve and the second solenoid valve, control means, second When the oil level of the compressor is detected to be low, the first solenoid valve is closed, and the second solenoid valve is opened.When the oil level of the second compressor is not detected to be low, the first solenoid valve is closed. the solenoid valve opens, the second electromagnetic valve is to be you closed.

Thereby, when it is detected that the oil level of the second compressor is low, among the oil return pipes to the first compressor, a return pipe having a small flow path resistance is selected. The amount of oil returned to the machine increases. When the amount of oil sucked by the compressor increases, the amount of oil flowing into the compression chamber of the compressor together with the refrigerant also increases, and the amount of oil contained in the refrigerant discharged from the compressor also increases. Thereafter, the refrigerant and the oil are separated by an oil separator provided on the discharge side of the compressor, and the separation efficiency ((the ratio of the amount of oil contained in the refrigerant discharged from the compressor−the amount of oil after passing through the oil separator) The ratio of the amount of oil contained in the refrigerant) / the amount of the oil contained in the refrigerant discharged from the compressor)) is substantially constant, for example, about 80 to 90%, and the remaining 10 to 20% of the oil is not separated. Is discharged to the refrigerant circuit together with the refrigerant. As a result, when the amount of oil returned to the first compressor increases, the amount of oil discharged from the first compressor to the refrigerant circuit also increases.

In the air conditioner of the present invention, the control means performs control to close the first solenoid valve and open the second solenoid valve when it is detected that the oil level of the second compressor is low. after a predetermined time has elapsed since even when the oil level of the second compressor is not recovered, the first solenoid valve, in which together with the open second solenoid valve.

  As a result, since both the first flow path resistance and the second flow path resistance connected in parallel are used, the flow path resistance is minimized, and the amount of oil returned to the first compressor increases. As in the above-described operation, the amount of oil flowing from the first compressor to the refrigerant circuit is further increased.

Further, in the air conditioner of the present invention, the control means, when it is detected that the oil level of the second compressor is low, control to close the first solenoid valve, open the second solenoid valve, or The control is performed to open both the first solenoid valve and the second solenoid valve, and the rotation speed of the second compressor is set to substantially the maximum rotation speed.

  Thereby, since the rotation speed of the second compressor is substantially maximized, the amount of refrigerant compressed by the second compressor increases.

  In the air conditioner of the present invention, when a decrease in the oil level is detected in the compressor driven by the electric motor, the amount of oil flowing in the refrigerant circuit is increased, so that the oil discharged from the first compressor to the refrigerant circuit is increased. As a result, the amount of oil returning to the compressor driven by the electric motor also increases, thereby making it possible to eliminate a decrease in the oil level of the compressor driven by the electric motor.

Configuration diagram of the refrigeration cycle of the air conditioner of the present invention Schematic diagram of oil level detection means

The first invention includes a first compressor for a gas engine which is connected in parallel within the refrigeration cycle as a driving source, a second air-conditioning by circulating the refrigerant by a compressor of which the electric motor as a drive source In the air conditioner to be performed, first and second oil separators for separating the refrigerant and the lubricating oil respectively on the discharge sides of the first and second compressors, and the lubricating oil separated by the first oil separator A first oil return pipe for leading to the suction side of one compressor, and a second oil return pipe for leading the lubricating oil separated by the second oil separator to the suction side of the second compressor. And

Further, the first oil return pipe is branched into a first solenoid valve and a first flow path resistance, and a second solenoid valve and a second flow path resistance having a smaller resistance than the first flow path resistance. Control means for controlling the opening and closing of the first solenoid valve and the second solenoid valve based on a signal from an oil level detecting means provided in the second compressor The control means opens the first solenoid valve and closes the second solenoid valve when it is detected that the oil level of the second compressor is high, and when the oil level of the second compressor is low, Upon detection, the first solenoid valve is closed and the second solenoid valve is closed.

  Accordingly, when it is detected that the oil level of the second compressor is low, a return pipe having a small flow path resistance among the oil return pipes to the first compressor is selected. The amount of oil returned to the machine increases. When the amount of oil sucked by the compressor increases, the amount of oil flowing into the compression chamber of the compressor together with the refrigerant also increases, and the amount of oil contained in the refrigerant discharged from the compressor also increases. Thereafter, the refrigerant and the oil are separated by the oil separator provided on the discharge side of the compressor, but the amount of the oil discharged to the refrigerant circuit together with the refrigerant without being separated increases. Therefore, when the amount of oil returned to the first compressor is increased, the amount of oil discharged from the first compressor to the refrigerant circuit is also increased.

  As a result, the amount of oil flowing through the refrigerant circuit increases, so that the amount of oil returning to the second compressor also increases, and a decrease in the oil level of the second compressor can be eliminated.

According to a second aspect, in the air conditioner of the first aspect, the control means closes the first solenoid valve and sets the second solenoid valve when it is detected that the oil level of the second compressor is low. If the oil level of the second compressor does not recover even after a predetermined time has elapsed since the control for opening, the first solenoid valve and the second solenoid valve are both opened.

  As a result, since both the first flow path resistance and the second flow path resistance connected in parallel are used, the flow path resistance becomes the smallest, and the amount of oil returned to the first compressor increases. In addition to the effect of the first invention, it is possible to further increase the amount of oil discharged from the first compressor to the refrigerant circuit, thereby eliminating a decrease in the oil level of the second compressor.

According to a third aspect, in the air conditioner of the first or second aspect, the control means closes the first solenoid valve when the oil level of the second compressor is detected to be low, The control for opening the solenoid valve or the control for opening both the first solenoid valve and the second solenoid valve is performed, and the rotation speed of the second compressor is set to substantially the maximum rotation speed. As a result, the amount of refrigerant compressed by the second compressor increases, the amount of oil returned circulating in the circuit together with the refrigerant increases, and the decrease in the oil level of the second compressor can be eliminated more quickly.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited by this embodiment.

(Embodiment 1)
FIG. 1 shows a refrigeration cycle configuration of the air conditioner of the present embodiment. The air conditioner in FIG. 1 has a so-called multi-configuration in which two indoor units are connected to one outdoor unit. The configuration of the refrigeration cycle is not limited to that shown in FIG. For example, two or more outdoor units and three or more indoor units can be connected in parallel.

  Reference numeral 100 denotes an outdoor unit, and the outdoor unit 100 and the indoor units 200 and 210 are connected by a pipe through which a refrigerant flows. In the outdoor unit 100, 111 is, for example, an engine using gas as a driving source, 112 is an engine driving compressor that obtains driving force from the engine 111 and compresses refrigerant, and 113 is a power supply driving compressor driven by electric power such as a commercial power supply. . The engine driven compressor 112 and the power supply driven compressor 113 are connected in parallel in the refrigeration cycle. The excluded volume of the engine-driven compressor 112 is larger than the excluded volume of the power-driven compressor 113. The lubricating oil of the engine-driven compressor 112 and the power-driven compressor 113 is the same refrigerating machine oil.

  Further, the discharge and suction pipes of the engine-driven compressor 112 are thicker than the discharge and suction pipes of the power supply-driven compressor 113. This suppresses an increase in pressure loss in the discharge and suction pipes of the non-power-supply-driven compressor having a large refrigerant flow rate, and reduces the amount of refrigerating machine oil returned from the refrigeration cycle to the engine-driven compressor 112 by reducing the power-supply compression Machine 113.

  An accumulator 114 is connected to a refrigerant pipe opposite to the two compressors from a junction of a suction pipe of the engine drive compressor 112 and a suction pipe of the power supply drive compressor 113, and supplies gas refrigerant to both compressors. Supply.

  Reference numerals 115a and 115b denote oil separators, which are installed in the refrigerant pipes on the discharge side of the engine driven compressor 112 and the discharge side of the power supply driven compressor 113, and separate the oil contained in the gas discharged from both compressors. The oil separated by the oil separator 115a is returned to the suction pipe of the engine drive compressor 112 by an oil return pipe 140a and returned to the suction pipe of the power supply drive compressor 113 by an oil return pipe 140b. Further, an oil return pipe opening / closing valve 150a, a flow path resistance 160a, an oil return opening / closing valve 150b, and a flow path resistance 160b are connected in parallel to the oil return pipe 140a via a branch portion. The resistance value of the flow path resistance 160a is set to be larger than the resistance value of the flow path resistance 160b. Further, a side surface of the power-driven compressor 113 and a suction pipe of the power-driven compressor 113 are connected via an oil level detecting means 170 described later.

  116 is a four-way valve for switching the refrigerating cycle between cooling and heating, and 117 is an outdoor unit decompression device for expanding the refrigerant. Reference numeral 118 denotes an engine exhaust heat exchanger for exchanging heat between the high-temperature cooling water used for cooling the engine 111 and the refrigerant, and is used for heating. Reference numeral 119 denotes a refrigerant flow control valve for the engine exhaust heat exchanger for adjusting the flow rate of the refrigerant flowing into the engine exhaust heat exchanger 118. Reference numeral 120 denotes an outdoor blower that supplies air around the outdoor unit 100 to the outdoor heat exchanger 130.

  In the indoor unit 200, 201 is an indoor air heat exchanger, 202 is an indoor blower fan that supplies air around the indoor unit 200 to the indoor air heat exchanger 201, and 203 is an indoor unit decompression device that expands refrigerant. Similarly, in the indoor unit 210, 211 is an indoor air heat exchanger, 212 is an indoor blower fan that supplies air around the indoor unit 210 to the indoor air heat exchanger 211, and 213 is an indoor unit decompression device that expands refrigerant. .

  Next, the detection means 170 for detecting the oil level in the power supply drive compressor 113 will be described with reference to FIG. The side surface of the power supply driven compressor and the suction pipe are connected by an oil level detection pipe 172 via a capillary tube 171, and an oil temperature detecting means for detecting the temperature of the pipe is provided between the capillary tube 171 and the suction pipe. 173 are provided. Further, a discharge pipe of the power supply drive compressor 113 is provided with discharge temperature detecting means 174 for detecting the temperature of the discharged refrigerant. The connection position of the oil level detection pipe 172 in the power supply driven compressor 113 is provided at a height where the oil amount in the power supply driven compressor 113 is the minimum oil amount position to be secured.

  Next, the detecting operation of the detecting means 170 will be described. The inside of the power-driven compressor 113 is at a high pressure due to the compressed refrigerant. During the operation of the power-driven compressor 113, the power is always supplied to the low-pressure suction pipe through the oil level detecting pipe 172. A fluid flow in the compressor 113 occurs. Since the capillary tube 171 is provided in the oil level detection pipe 172, the fluid flowing through the oil level detection pipe is depressurized by the capillary tube 171 and flows to the suction pipe. At this time, if a sufficient amount of oil is secured in the power-driven compressor 113, the fluid flowing through the oil level detection pipe 172 becomes oil, and conversely, a sufficient amount of oil is stored in the power-driven compressor 113. When the oil is not secured, the fluid flowing through the oil level detection pipe 172 becomes a refrigerant gas. When the fluid flowing through the oil level detection pipe 172 is oil, the temperature of the fluid after passing through the capillary tube does not drop due to the pressure drop. Therefore, the temperature Toil detected by the oil temperature detection means 173 is equal to the discharge temperature detection. The temperature is substantially the same as the discharge temperature Tdis detected by the means 174. On the other hand, when the fluid flowing through the oil level detection pipe 172 is a refrigerant gas, the temperature of the fluid after passing through the capillary tube drops due to the pressure drop, and the temperature Toil detected by the oil temperature detection means 173 is the discharge temperature. The temperature is lower than the discharge temperature Tdis detected by the detection means 174. By detecting the temperature difference between Toil and Tdis, the detecting means 170 detects an excess or deficiency in the amount of lubricating oil in the power supply driving compressor 113.

  Next, the operation of the outdoor unit 100 and the indoor units 200 and 210 will be described. During the cooling operation, the four-way valve 116 is set so that the refrigerant flows in a solid line (see FIG. 1). The high-temperature and high-pressure refrigerant compressed by the engine-driven compressor 112 and the power-supply-driven compressor 113 joins and then flows into the oil separator 115. The high-purity gas refrigerant from which the refrigerating machine oil has been separated by the oil separator 115 passes through the four-way valve 116 and enters the outdoor heat exchanger 130. The gas refrigerant exchanges heat with the outside air in the outdoor heat exchanger 130, radiates heat, condenses, becomes a high-pressure liquid refrigerant, passes through the outdoor unit decompression device 117, and is supplied to the indoor units 200 and 210.

  The high-pressure liquid refrigerant that has entered the indoor unit 200 is decompressed by the indoor unit decompression device 203, enters a gas-liquid two-phase state, and flows into the indoor heat exchanger 201. The refrigerant in the gas-liquid two-phase state exchanges heat with air in the air-conditioned space in the indoor heat exchanger 201, absorbs heat, evaporates, and flows out of the indoor unit 200 as gas refrigerant.

The high-pressure liquid refrigerant that has entered the indoor unit 200 is decompressed by the indoor unit decompression device 203, enters a gas-liquid two-phase state, and flows into the indoor heat exchanger 201. The refrigerant in the gas-liquid two-phase state exchanges heat with the air in the space to be air-conditioned in the indoor heat exchanger 201, absorbs heat, evaporates, and flows out from the indoor unit 200 as a gas refrigerant.

  In the indoor unit 210 as well, similarly to the indoor unit 200, first, the high-pressure liquid refrigerant is depressurized by the indoor unit decompression device 213, enters a gas-liquid two-phase state, and flows into the indoor heat exchanger 211. The refrigerant in the gas-liquid two-phase state exchanges heat with air in the space to be air-conditioned in the indoor heat exchanger 211, absorbs heat, evaporates, and flows out from the indoor unit 210 as gas refrigerant.

  When only the indoor unit 200 performs the cooling operation, the indoor unit decompression device 213 is closed, and the refrigerant is not supplied to the indoor heat exchanger 211 of the indoor unit 210. On the other hand, when only the indoor unit 210 performs the cooling operation, the indoor unit decompression device 203 is closed, and the refrigerant is not supplied to the indoor heat exchanger 201 of the indoor unit 200.

  The gas refrigerant flowing out of the indoor units 200 and 210 returns to the outdoor unit 100 again. The gas refrigerant flowing into the outdoor unit 100 passes through the four-way valve 116 and the accumulator 114 and returns to the engine-driven compressor 112 and the power-driven compressor 113.

  The operation method of the engine drive compressor 112 and the power supply drive compressor 113 during the cooling operation is, for example, as follows.

  If the cooling load is smaller than the cooling capacity when the engine-driven compressor 112 is operated at the lowest operating frequency (the minimum cooling capacity of the engine-driven compressor 112), the engine-driven compressor 112 alone will enter intermittent operation. , And only the power supply driven compressor 113 is operated.

  The cooling capacity when the cooling load is larger than the minimum cooling load of the engine-driven compressor 112 and both the engine-driven compressor 112 and the power supply-driven compressor 113 are operated at the lowest operation frequency (when both compressors are operated) If it is smaller than (minimum cooling capacity), one of the engine-driven compressor 112 and the power-driven compressor 113, for example, the one with lower operation cost or smaller energy consumption is selected and operated.

  If the cooling load is larger than the minimum cooling capacity during the operation of both compressors, both the engine-driven compressor 112 and the power supply-driven compressor 113 are operated so that, for example, the operating cost or the energy consumption is minimized. I do. In this case, the operating frequency or the operating cost of each compressor or the operating cost or the energy consumption is determined in order to determine the operating frequency of the engine drive compressor 112 and the power supply compressor 113 to minimize the energy consumption. Take advantage of the relationship.

  Actually, the ratio of the cooling load that the engine-driven compressor 112 bears to the entire cooling load is determined by the maximum cooling capacity when both compressors are operated at the maximum operating frequency (the maximum cooling capacity when both compressors are operated). Is about ± 15% of the cooling capacity when only the engine-driven compressor 112 is operated at the maximum operating frequency.

  Next, in the heating operation, the four-way valve 116 is set to flow the refrigerant in a dotted line (see FIG. 1). The high-temperature and high-pressure refrigerant compressed by the engine-driven compressor 112 and the power-supply-driven compressor 113 joins and then flows into the oil separator 115. The high-purity gas refrigerant from which the refrigerating machine oil has been separated by the oil separator 115 passes through the four-way valve 116, exits the outdoor unit 100, and is supplied to the indoor units 200 and 210.

The high-temperature and high-pressure gas refrigerant that has entered the indoor unit 200 flows into the indoor heat exchanger 201. The high-temperature and high-pressure gas refrigerant exchanges heat with the air in the space to be air-conditioned in the indoor heat exchanger 201, radiates heat, condenses, becomes high-pressure liquid refrigerant, and passes through the indoor unit decompression device 203. , Indoor unit 20
Flows out of zero.

  In the indoor unit 210, similarly to the indoor unit 200, first, the high-temperature and high-pressure gas refrigerant flows into the indoor heat exchanger 211. The high-temperature and high-pressure gas refrigerant exchanges heat with the air in the space to be air-conditioned in the indoor heat exchanger 211, radiates heat, condenses, becomes high-pressure liquid refrigerant, and passes through the indoor unit decompression device 213. Out of the indoor unit 210.

  As in the case of cooling, when only the indoor unit 200 performs the heating operation, the indoor unit decompressor 213 is closed, and the refrigerant is not supplied to the indoor heat exchanger 211 of the indoor unit 210. On the other hand, when only the indoor unit 210 performs the heating operation, the indoor unit decompression device 203 is closed, and the refrigerant is not supplied to the indoor heat exchanger 201 of the indoor unit 200.

  The high-pressure liquid refrigerant flowing out of the indoor units 200 and 210 returns to the outdoor unit 100 again. The high-pressure liquid refrigerant that has flowed into the outdoor unit 100 is depressurized by the outdoor unit decompression device 117, enters a gas-liquid two-phase state, and flows into the outdoor heat exchanger 130 and the engine exhaust heat exchanger 118. The refrigerant in the gas-liquid two-phase state evaporates after absorbing heat by exchanging heat with the outside air in the outdoor heat exchanger 130 and with the high-temperature cooling water used for cooling the engine 111 in the engine exhaust heat exchanger 118. , Through the pressure reducing four-way valve 116 and the accumulator 114, and returns to the engine driven compressor 112 and the power supply driven compressor 113.

  The operation method of the engine drive compressor 112 and the power supply drive compressor 113 during the heating operation is, for example, as follows.

  If the heating load is smaller than the heating capacity when the engine-driven compressor 112 is operated at the lowest operating frequency (the minimum heating capacity of the engine-driven compressor 112), the engine-driven compressor 112 alone will enter intermittent operation. , And only the power supply driven compressor 113 is operated.

  The heating capacity when the heating load is larger than the minimum heating load of the engine-driven compressor 112 and both the engine-driven compressor 112 and the power supply-driven compressor 113 are operated at the lowest operation frequency (when both compressors are operated) If it is smaller than (minimum heating capacity), one of the engine-driven compressor 112 and the power-driven compressor 113, for example, the one with lower operation cost or smaller energy consumption is selected and operated.

  When the heating load is larger than the minimum heating capacity during the operation of both compressors, both the engine-driven compressor 112 and the power supply-driven compressor 113 are operated so that, for example, the operation cost or the energy consumption is minimized. I do. In this case, the operating frequency or the operating cost of each compressor or the operating cost or the energy consumption is determined to determine the operating frequency of the engine-driven compressor 112 and the power-driven compressor 113 to minimize the operating cost or the energy consumption. Take advantage of the relationship.

  Actually, the ratio of the heating load that the engine-driven compressor 112 bears to the entire heating load is the maximum heating capacity when both compressors are operated at the maximum operating frequency (the maximum heating capacity when both compressors are operated). Is about ± 15% of the heating capacity when only the engine-driven compressor 112 is operated at the maximum operating frequency.

  However, during the heating operation, the frost formation state of the outdoor heat exchanger 130 is constantly monitored. If there is a danger of frost formation, the operation cost or the compressor of each compressor is minimized so that the energy consumption is minimized. Even if the operating frequency is set, control is performed to increase the operating frequency of the engine-driven compressor 112 and decrease the operating frequency of the power-driven compressor 113.

  When the operating frequency of the engine-driven compressor 112 is increased, the amount of exhaust heat of the engine 111 increases, and the amount of cooling water supplied to the engine exhaust heat exchanger 118 also increases. That is, more refrigerant can be evaporated in the engine exhaust heat exchanger 118, and the amount of refrigerant flowing to the outdoor heat exchanger 130 is reduced, thereby reducing the risk of frost formation.

  Next, the operation of the oil return pipe opening / closing valves 150a and 150b will be described. The opening and closing of the oil return pipe opening / closing valves 150a and 150b are controlled by an oil level detecting means 170 and a control device (not shown). If the oil level detecting means 170 detects that the oil amount in the power-driven compressor 113 is not low, the oil amounts in the engine-driven compressor 112 and the power-driven compressor 113 are balanced, and the control device Controls the oil return on-off valve 150a to open, the 150b to close, and the use of the flow path resistance 160a having a large resistance value to restrict the amount of oil returning from the oil separator 115a to the engine drive compressor 112.

  On the other hand, when the oil level detecting means 170 detects that the amount of oil in the power-driven compressor 113 is small, the oil amounts in the engine-driven compressor 112 and the power-driven compressor 113 are uneven, and the control device Controls the oil return on-off valve 150a to be closed, the oil return valve 150b to be opened, and the flow resistance 160b having a small resistance value to be used to increase the amount of oil returning from the oil separator 115a to the engine drive compressor 112.

  When the amount of oil flowing to the engine compressor 112 increases, the amount of oil flowing into the compression chamber of the engine drive compressor 113 together with the refrigerant increases, and the amount of oil contained in the refrigerant discharged from the engine drive compressor 112 also increases. . Thereafter, the refrigerant and the oil are separated by the oil separator 115a provided on the discharge side of the engine drive compressor 112, but the oil amount discharged to the refrigerant circuit together with the refrigerant without being separated increases. Therefore, when the amount of oil returned to the engine drive compressor 112 is increased, the amount of oil discharged from the engine drive compressor 112 to the refrigerant circuit also increases.

  As a result, the amount of oil flowing through the refrigerant circuit increases, so that the amount of oil returning to the power supply driven compressor 113 also increases, and a decrease in the oil level of the power supply driven compressor 113 can be eliminated.

(Embodiment 2)
If the oil level in the power-driven compressor 113 is detected by the oil-level detecting means 170 to be small, and the oil level in the power-driven compressor 113 is not recovered even when the control of the first embodiment is performed, The device may open both the oil return on-off valves 150a and 150b.

  In this case, since both the flow path resistance 160a and the flow path resistance 160b connected in parallel are used, the flow path resistance is the smallest, and the amount of oil returned to the engine drive compressor 112 is further increased.

  v As a result, in addition to the operation of the first embodiment, the amount of oil discharged from the engine-driven compressor 112 to the refrigerant circuit can be further increased, and a decrease in the oil level of the power-driven compressor 113 can be eliminated. Other configurations and controls are the same as those in the first embodiment, and thus description thereof will be omitted.

(Embodiment 3)
The oil level detecting means 170 detects that the amount of oil in the power-driven compressor 113 is small, and controls the first or second embodiment. Control for maximizing may be performed.

In this case, the amount of refrigerant compressed by the power supply drive compressor 113 increases, and the amount of oil returned to circulate in the circuit together with the refrigerant also relatively increases. For this reason, the decrease in the oil level of the power supply drive compressor 113 can be eliminated more quickly. Other configurations and controls are the same as those in the first embodiment, and thus description thereof will be omitted.

  INDUSTRIAL APPLICATION This invention can be utilized suitably as an air conditioner which reduces operation cost or energy consumption.

REFERENCE SIGNS LIST 100 Outdoor unit 111 Engine 112 Engine-driven compressor 113 Power-driven compressor 114 Accumulator 115 Oil separator 116 Four-way valve 117 Outdoor unit decompression device 120 Outdoor blowing fan 130 Outdoor heat exchanger 150 Oil return on-off valve 160 Flow resistance 170 Oil level detection Means 200, 210 Indoor unit

Claims (3)

A first compressor for a gas engine which is connected in parallel with the refrigeration cycle as a drive source, an electric motor to circulate the refrigerant through a second compressor whose drive source in the air conditioner for performing air conditioning, and first and second oil separator for separating the respective refrigerant and the lubricating oil to the discharge side of the first and second compressors, the compression of the lubricating oil separated by the first oil separator of the first a first oil return pipe for guiding the suction side of the machine, and a second oil return pipe for guiding the lubricating oil separated by the second oil separator on the suction side of the second compressor, Has,
Wherein the first oil return pipe, the first solenoid valve and the first flow resistance, and the second of the second resistor is smaller than the electromagnetic valve first flow path resistance of the flow path resistance is branched It provided in parallel through the parts, on the basis of a signal from the oil level detecting means provided in the second compressor, the control for controlling the opening and closing of the first solenoid valve and the second solenoid valve comprising means, the control means, the second oil level of the compressor when the sensed low closing the first solenoid valve, the second solenoid valve is opened, the second when the oil level of the compressor is not detected to be low, the first solenoid valve open, an air conditioner, wherein the closing and to Turkey the second solenoid valve. The air conditioner according to claim 1, wherein, when the oil level of the second compressor is detected to be low, the first solenoid valve closed, the second solenoid valve opens and after a predetermined time has elapsed control after performing the, when the oil level of the second compressor is not recovered, the first solenoid valve, both the open and to Turkey the second solenoid valve An air conditioner characterized by: The air conditioner according to claim 1 or 2, wherein the control means, when the oil level of the second compressor is detected to be low, closing the first solenoid valve, the second solenoid valve control of the opening, or the first solenoid valve, performs control to both open the second solenoid valve, characterized in that the rotational speed of the second compressor and approximately maximum rotational speed Air conditioner.

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