Refrigeration cycle device

Abstract

Provided is a refrigeration cycle device comprising: a compressor having a low-pressure shell in which a motor is disposed in a low-pressure atmosphere; a condenser; a depressurizing device; and an evaporator. In the refrigeration cycle device, the compressor, the condenser, the depressurizing device, and the evaporator are connected using piping, and a heat medium circulates. The refrigeration cycle device further comprises a pressure increasing mechanism having: an inlet port into which the heat medium branched from between the compressor and the condenser flows; an oil port into which oil sucked from the compressor flows due to driving force of the heat medium flowing in through the inflow port; and an outlet port through which the oil flowing in through the oil port is mixed with the heat medium and flows out toward the suction side of the compressor.

Description

Refrigeration cycle apparatus

[0001] The present disclosure relates to a refrigeration cycle apparatus, and particularly to a refrigeration cycle apparatus including a low-pressure shell type compressor.

[0002] A refrigerating machine oil is enclosed in the refrigeration cycle apparatus to maintain the reliability of a compressor having a sliding portion such as a rotary compressor, a scroll compressor, or a screw compressor. In the field of refrigeration cycle apparatuses, technologies for improving reliability through oil management and technologies for improving energy saving performance through oil flow control have been proposed.

[0003] For example, there is known a technology in which an oil discharge pipe is provided at the bottom of a compressor and connected to a discharge pipe to control so that no more than a predetermined amount of oil accumulates inside the compressor. There is also known a technology in which an oil-phase pipe for returning oil separated by an oil separator is provided at the bottom of the compressor, and the oil is returned by utilizing the height difference between the oil separator and the compressor.

[0004] The above-mentioned technologies relate to high-pressure shell type compressors, that is, compressors having a shell with a high-pressure structure, and cannot be directly applied to low-pressure shell type compressors.

[0005] On the other hand, Patent Document 1 discloses a configuration in which a partition plate is provided inside an oil separator in a low-pressure shell type compressor. The upper part of the oil separator is a high-pressure space connected to a discharge pipe in the refrigeration cycle apparatus, the lower part is a low-pressure space connected to a low-pressure part of the compressor, and the upper part and the lower part of the oil separator are connected by a capillary tube.

[0006] Japanese Utility Model Laid-Open Publication No. 04-062387

[0007] According to the configuration of Patent Document 1, the amount of oil in the compressor can be maintained even when the discharge amount increases. However, when the amount of oil in the compressor increases, there is a possibility that the oil level rises to the rotating part. When the oil level rises to the rotating part, the oil is agitated by the rotating part, which may cause problems such as an increase in electrical input. As described above, sufficient countermeasures have not been taken for the case where the amount of oil in the compressor exceeds an appropriate level.

[0008] An object of the present disclosure is to provide a refrigeration cycle apparatus capable of appropriately maintaining the amount of oil in a compressor.

[0009] The refrigeration cycle apparatus according to this disclosure comprises a compressor having a low-pressure structure shell in which a motor is installed in a low-pressure atmosphere, a condenser, a depressurizing device, and an evaporator, wherein the compressor, the condenser, the depressurizing device, and the evaporator are connected by piping and a heat transfer medium is circulated, and the apparatus is equipped with a pressure boosting mechanism having an inlet port into which the heat transfer medium branches off and flows in from between the compressor and the condenser, an oil port into which oil drawn from the compressor by the driving force of the heat transfer medium flowing in from the inlet port flows in, and an outlet port into which the oil flowing in from the oil port is mixed with the heat transfer medium and flows out to the suction side of the compressor.

[0010] According to the refrigeration cycle device described herein, a pressure boosting mechanism is provided, and the driving force of the heat transfer medium flowing in from the inlet port of the pressure boosting vessel can draw oil from the compressor and return it to the suction side of the compressor, thereby maintaining an appropriate amount of oil in the compressor.

[0011] This is a circuit diagram of the refrigeration cycle device according to Embodiment 1. This is a schematic diagram of the pressure boosting mechanism of the refrigeration cycle device according to Embodiment 1. This is a schematic cross-sectional view of the compressor of the refrigeration cycle device according to Embodiment 1. This is a circuit diagram illustrating the oil extraction operation in the refrigeration cycle device according to Embodiment 1. This is a circuit diagram illustrating the first oil return operation in the refrigeration cycle device according to Embodiment 1. This is a circuit diagram illustrating the second oil return operation in the refrigeration cycle device according to Embodiment 1. This is a schematic partial cross-sectional view of the compressor of the refrigeration cycle device according to a modified example of Embodiment 1.

[0012] The embodiments for implementing this disclosure will be described with reference to the attached drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are simplified or omitted as appropriate. In the following description, for convenience, the positional relationships of each structure may be expressed based on the illustrated state. This disclosure is not limited to the following embodiments, and any combination of embodiments, any modification of any component of each embodiment, or any omission of any component of each embodiment is possible without departing from the spirit of this disclosure. In addition, the dimensional relationships or shapes of each component in each drawing may differ from those of the actual components. Furthermore, the positional relationships between each component, such as the top-down relationship, are, in principle, as they are when installed in a usable state. However, in order to facilitate understanding, terms indicating direction, such as "up," "down," "right," "left," "front," and "back," will be used as appropriate, but these notations are merely for the convenience of explanation and do not limit the arrangement and orientation of the device or parts.

[0013] Embodiment 1. Figure 1 is a circuit diagram of a refrigeration cycle device 100 according to Embodiment 1. As shown in Figure 1, the refrigeration cycle device 100 includes a compressor 10, an oil separator 11, a condenser 12, a pressure reducing device 13, and an evaporator 14. The compressor 10, the oil separator 11, the condenser 12, the pressure reducing device 13, and the evaporator 14 are connected in a ring by piping 100a, forming a main circuit R. Refrigerant flows through piping 100a and circulates through the main circuit R.

[0014] An accumulator 15 is connected between the evaporator 14 and the compressor 10. The refrigeration cycle device 100 also includes a pressure boosting mechanism 19.

[0015] The refrigeration cycle device 100 may be, for example, a household air conditioner or a multi-split air conditioner for buildings, in which case the main circuit R may be equipped with a four-way valve that switches the direction of refrigerant flow. A multi-split air conditioner for buildings is an air conditioner configured in which a number of indoor units, each equipped with a user-side heat exchanger that functions as a condenser 12 or evaporator 14, are connected to the main circuit R.

[0016] [Compressor 10] The compressor 10 compresses a low-temperature and low-pressure refrigerant to produce a high-temperature and high-pressure gaseous refrigerant. Since the compressor 10 has sliding parts, it is sealed with refrigerant oil to lubricate the sliding parts. Note that refrigerant oil is sometimes simply referred to as oil.

[0017] The compressor 10 has a low-pressure structure shell 110 in which the motor 101 is placed in a low-pressure atmosphere L. The shell 110 is, for example, cylindrical in shape with the vertical direction as its axial direction, and houses the motor 101 and the compression mechanism 102 inside. The motor 101 consists of a stator 101a fixed to the inner wall of the shell 110 and a rotor 101b slidably arranged on the inner circumference side of the stator 101a. The compression mechanism 102 is located above the motor 101.

[0018] The compression mechanism 102 draws in refrigerant and compresses and discharges it using rotational force generated by a motor 101 transmitted via a crankshaft 103 extending axially from the compressor 10. The discharged refrigerant creates a high-pressure atmosphere H above the compression mechanism 102.

[0019] An oil passage is formed in the crankshaft 103 that penetrates axially, and an oil pump 103a is provided at the lower end of the oil passage. The oil pump 103a is provided to draw up oil from the oil reservoir 104 formed at the bottom of the shell 110 and supply oil to each sliding part of the compressor 10. The oil supplied to each sliding part of the compressor 10 is discharged into the main circuit R together with high-temperature and high-pressure gaseous refrigerant.

[0020] The shell 110 has an intake pipe 105 and a discharge pipe 106 inserted into it. The intake pipe 105, for example, is inserted through the side of the shell 110 and draws in low-temperature and low-pressure gaseous refrigerant and guides it into the interior of the shell 110. The discharge pipe 106, for example, is inserted through the upper end of the shell 110 and discharges high-temperature and high-pressure gaseous refrigerant to the main circuit R.

[0021] [Oil Separator 11] The oil separator 11 separates the high-temperature and high-pressure refrigerant containing oil, which flows in via the main circuit R, into gas and liquid. The gas generally contains gaseous refrigerant, and the liquid generally contains oil. The volume of the oil separator 11 is, for example, 100 cc to 1 L. An inlet 111 is formed on the side of the oil separator 11, an outlet 112 is formed at the top, and an oil return port 113 is formed at the bottom. Of the high-temperature and high-pressure refrigerant that flows in from the inlet 111, the gas flows out from the outlet 112 and flows through the main circuit R, and the liquid flows out from the oil return port 113.

[0022] [Condenser 12] The condenser 12 is a heat exchanger into which high-temperature and high-pressure gaseous refrigerant flows and exchanges heat with the surrounding heat transfer medium. The heat transfer medium is, for example, air, in which case the condenser 12 is, for example, a fin-and-tube type heat exchanger. The type of heat transfer medium and the configuration of the heat exchanger are not particularly limited. In the condenser 12, the high-temperature and high-pressure refrigerant exchanges heat with the low-temperature heat transfer medium surrounding the condenser 12, heating the surrounding heat transfer medium, causing it to liquefy, and then flows out as liquid refrigerant.

[0023] [Pressure Reducing Device 13] The pressure reducing device 13 reduces the pressure of the liquid refrigerant to make it a low-pressure liquid refrigerant. The pressure reducing device 13 is, for example, an expansion valve.

[0024] [Evaporator 14] The evaporator 14 is a heat exchanger into which a low-pressure refrigerant flows and exchanges heat with the surrounding heat transfer medium. Similar to the condenser 12, the heat transfer medium in the evaporator 14 is, for example, air, in which case the condenser 12 is, for example, a fin-and-tube type heat exchanger. The type of heat transfer medium and the configuration of the heat exchanger are not particularly limited. In the evaporator 14, the medium-pressure refrigerant exchanges heat with the high-temperature heat transfer medium surrounding the evaporator 14, cools the surrounding heat transfer medium, evaporates, and flows out as a gas or two-phase refrigerant.

[0025] [Accumulator 15] The accumulator 15 stores excess refrigerant and liquid refrigerant that could not be completely evaporated in the evaporator 14, separated from the gaseous refrigerant. The volume of the accumulator 15 is, for example, 10 L to 20 L. The presence of the accumulator 15 prevents damage to valves or valve covers, etc., caused by liquid compression resulting from the inhalation of liquid refrigerant that could not be completely evaporated into the compressor 10.

[0026] [Pressure Boosting Mechanism 19] The pressure boosting mechanism 19 is, for example, an ejector that uses a high-pressure fluid supplied inside to draw in a low-pressure fluid, mixes the high-pressure fluid and the low-pressure fluid, and discharges the mixture. The pressure boosting mechanism 19 is connected to the accumulator 15 by a first path P1, to the oil separator 11 by a second path P2, and to the oil reservoir 104 of the compressor 10 by a third path P3.

[0027] Figure 2 is a schematic diagram of the pressure boosting mechanism 19 of the refrigeration cycle device 100 according to Embodiment 1. As shown in Figure 2, the pressure boosting mechanism 19 has an inlet port 191, an oil port 193, and an outlet port 192.

[0028] The inlet port 191 is an opening through which the heat transfer medium, as a high-pressure fluid, flows in from the return oil port 113 of the oil separator 11 via the second path P2. A flow rate adjustment device 18 is provided in the second path P2. The operation of the flow rate adjustment device 18 is controlled, for example, by a control device 20. The flow rate adjustment device 18 adjusts the flow rate of the heat transfer medium flowing in from the oil separator 11.

[0029] The oil port 193 is an opening through which oil from the oil reservoir 104 of the compressor 10 flows in via the third path P3. The oil is drawn into the boosting mechanism 19 by the driving force of the heat transfer medium flowing in from the inlet port 191 and flows in through the oil port 193. A second on-off valve 195 is provided in the third path P3. The operation of the second on-off valve 195 is controlled, for example, by a control device 20.

[0030] The third path P3 penetrates the shell 110 of the compressor 10 and communicates with the oil reservoir 104. The inlet 104a at the tip of the third path P3 is located in the oil reservoir 104 and extends vertically upward. In the oil reservoir 104, the oil surface may become turbulent due to the flow of gaseous refrigerant. By having the tip of the third path P3 point vertically upward rather than horizontally or downward, it is possible to prevent gas from being drawn into the oil pump 103a when the oil surface is disturbed.

[0031] The outlet port 192 is an opening through which the heat transfer medium and oil mixed in the boosting mechanism 19 flow out. The heat transfer medium and oil flow into the upstream side of the accumulator 15 of the main circuit R via the first path P1. The oil that flows into the main circuit R is stored in the accumulator 15. The first path P1 is provided with a first on-off valve 194. The operation of the first on-off valve 194 is controlled, for example, by a control device 20. The first on-off valve 194 allows the flow of fluid through the first path P1.

[0032] The pressure boosting mechanism 19 uses the expansion power of the gaseous refrigerant contained in the high-pressure heat transfer medium that flows in from the inlet port 191 to draw oil from the oil storage section 104 through the oil port 193, mix it with the heat transfer medium, and discharge it through the outlet port 192. The oil mixed with the heat transfer medium that discharges from the outlet port 192 flows into the accumulator 15 via the main circuit R and is stored there.

[0033] [Oil level measuring means 17] Figure 3 is a schematic cross-sectional view of the compressor 10 of the refrigeration cycle device 100 according to Embodiment 1. As shown in Figure 3, an oil level measuring means 17 is provided at the bottom of the compressor 10. The oil level measuring means 17 is composed of, for example, a plurality of temperature sensors.

[0034] When multiple temperature sensors are used as the oil level measurement means 17, the multiple temperature sensors are arranged, for example, at equal intervals along the vertical direction of the compressor 10. Since the oil that accumulates in the oil reservoir 104 is oil that has been heated and separated by the compression mechanism 102, the portion of the oil reservoir 104 where the oil has accumulated is at a higher temperature than the surrounding low-temperature and low-pressure gaseous refrigerant.

[0035] As an oil level height measuring means 17, for example, the temperature of the lower part of the compressor 10 is measured by multiple temperature sensors, and the temperature distribution in the vertical direction of the compressor 10 is determined based on the measured temperature, thereby detecting the oil level height of the oil reservoir 104.

[0036] [Control device 20] The operation of the refrigeration cycle device 100 is controlled by the control device 20. The control device 20, for example, acquires a value detected from the oil level height measuring means 17 and calculates the oil level. The control device 20 also controls the opening degree of the flow rate adjustment device 18, for example. The control device 20 also performs oil extraction operation or oil return operation by controlling the opening and closing of the first on-off valve 194 and the second on-off valve 195, for example. The control device 20 also controls the rotational speed of the compressor 10 to adjust the amount of refrigerant discharged. Furthermore, if the refrigeration cycle device 100 has a four-way valve, the control device 20 controls the switching of the four-way valve to switch between cooling operation and heating operation.

[0037] The control device 20 is composed of, for example, a CPU (Central Processing Unit, central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, also called a DSP (Digital Signal Processor)). The control device 20 has memory composed of, for example, non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), magnetic disks, flexible disks, optical disks, compact disks, minidiscs, DVDs (Digital Versatile Disks), etc. The control device 20 performs processing using programs stored in memory. However, the control device 20 is not limited to this, and each part may be composed of separate dedicated devices.

[0038] <Refrigerant Operation> The refrigerant is compressed in the compression mechanism 102 of the compressor 10, becoming a high-temperature and high-pressure gaseous refrigerant, which is then discharged from the discharge pipe 106. The refrigerant discharged from the compressor 10 passes through the oil separator 11 and flows into the condenser 12, where it exchanges heat with the surrounding heat transfer medium, releases heat, and flows out at a low temperature. The refrigerant that flows out of the condenser 12 is depressurized in the depressurizing device 13, becoming low-pressure, and flows into the evaporator 14. In the evaporator 14, it absorbs heat from the surrounding heat transfer medium and evaporates, becoming a low-temperature and low-pressure gaseous two-phase refrigerant. The low-temperature and low-pressure gaseous two-phase refrigerant passes through the accumulator 15, becomes a gaseous refrigerant, and is drawn into the compressor 10.

[0039] <Oil Operation> Oil is drawn up from the oil reservoir 104 at the bottom of the compressor 10 by the oil pump 103a, passes through the oil passage that penetrates the crankshaft 103, and is supplied to each sliding part of the compressor 10, for example, to lubricate each sliding part such as bearings. A portion of the oil that has lubricated each sliding part returns to the bottom of the compressor 10 and is stored in the oil reservoir 104. The remaining portion of the oil that has lubricated each sliding part is discharged from the discharge pipe 106 together with the refrigerant, which has become high pressure and high temperature, and flows out into the main circuit R. The oil that has flowed out into the main circuit R flows into the oil separator 11, where it is separated from the gaseous refrigerant.

[0040] The oil separated by the oil separator 11 is processed by either an oil extraction operation or an oil return operation, depending on the oil level in the oil storage section 104.

[0041] <Oil Extraction Operation> Figure 4 is a circuit diagram illustrating the oil extraction operation in the refrigeration cycle device 100 according to Embodiment 1. As shown in Figure 4, during the oil extraction operation, the first on-off valve 194 and the second on-off valve 195 are controlled to the open state by the control device 20.

[0042] The oil extraction operation is an operation to extract oil from the oil reservoir 104, and is performed when the oil level in the oil reservoir 104 is higher than the appropriate oil level A. The appropriate oil level A is the oil level in the compressor 10 when the minimum amount of oil necessary for the sliding of bearings and the like is sealed inside.

[0043] A part of the heat medium separated by the oil separator 11 passes through the second path P2 and flows into the pressure increasing mechanism 19 from the inflow port 191. The heat medium is at high pressure and contains gas refrigerant. When the heat medium flows into the pressure increasing mechanism 19, the oil in the oil reservoir 104 is sucked from the oil port 193 via the third path P3 by the expansion power of the oil and gas refrigerant contained in the heat medium. The oil sucked from the oil port 193 is mixed with the heat medium in the pressure increasing mechanism 19 and reaches the outflow port 192. When the heat medium flows out from the outflow port 192 to the first path P1, it merges with the heat medium flowing through the main circuit R on the upstream side of the accumulator 15 in the main circuit R. Then, the oil that has reached the accumulator 15 is stored in the accumulator 15.

[0044] Since the oil reservoir 104 is in the low-pressure atmosphere L of the compressor 10, some kind of power is required to take out oil from the oil reservoir 104. By performing the oil extraction operation with the pressure increasing mechanism 19, the expansion power of a part of the heat medium separated by the oil separator 11 is used to generate a force for sucking oil, so that excess oil in the oil reservoir 104 can be taken out and directly stored in the accumulator 15.

[0045] Here, the flow rate of the heat medium flowing through the second path P2 is adjusted by the flow rate adjusting device 18. The flow rate adjusting device 18 is controlled by the control device 20 to be kept in a relatively open state to an extent that allows the gas refrigerant contained in the heat medium flowing through the second path P2 to flow in. For example, when the refrigeration cycle apparatus 100 is an air conditioner, the refrigerant pressure or refrigerant flow rate changes depending on conditions such as outside air temperature, indoor temperature, and the load of the indoor unit, so it is not easy to calculate the amount of gas refrigerant contained in the heat medium. Therefore, the flow rate adjusting device 18 is kept in a relatively open state to an extent that allows gas refrigerant to be contained in the heat medium even under the worst conditions.

[0046] In the pressure increasing mechanism 19, the effect of taking out oil is obtained by utilizing the influence of the expansion power of the gas refrigerant contained in the heat medium flowing through the second path P2. When the flow rate of the gas refrigerant flowing into the pressure increasing mechanism 19 increases, the flow rate of the refrigerant in the main circuit R decreases, and the cooling and heating capacity decreases. In the flow rate adjusting device 18, when the flow rate can be adjusted according to load conditions, excessive bypassing of the gas refrigerant through the pressure increasing mechanism 19 can be suppressed. By suppressing the bypass amount of the gas refrigerant, the flow rate of the refrigerant in the main circuit R can be increased, and energy saving performance can be improved.

[0047] When the compressor 10 constitutes a refrigeration cycle apparatus 100 used in a multi-type air conditioner for buildings, depending on the number of indoor units connected to the main circuit R, the pipe length may increase and may reach up to 1000 m. In such a case, part of the oil discharged from the compressor 10 flows to the indoor units connected to the main circuit R. Therefore, if the amount of oil sealed in the compressor 10 is too small, the oil that has flowed to the indoor units cannot be recovered, and oil depletion may occur. When the oil level height in the oil storage portion 104 becomes lower than the oil pump 103a due to oil depletion, oil cannot be sucked up, no oil is supplied to the sliding portions in the compressor 10, and the performance of the compressor 10 decreases.

[0048] Therefore, in order to prevent the sealed amount in the compressor 10 from becoming too small, the oil sealed amount is set with the maximum pipe length of the compressor 10 as the catalog value. On the other hand, in an installation state where the pipe length is shorter than the catalog value, the oil level in the compressor 10 is higher than the appropriate oil level height A, resulting in an excessive oil state. For example, a motor or the like may be immersed in oil, or oil may be stirred, which increases electrical input. In addition, stirring of the oil causes the oil to flow out into the refrigerant circuit, which changes the flow rate of the refrigerant itself in the refrigerant circuit and reduces the performance of the compressor 10.

[0049] Furthermore, the oil that flows out of the compressor 10 is separated and stored in the oil separator 11, but if the volume of the oil separator 11 is insufficient, it may overflow. An accumulator 15 is connected downstream of the oil separator 11 in the main circuit R, and it is also conceivable that the oil could be stored in the accumulator 15. However, it takes time for the oil to circulate through the main circuit R and reach the accumulator 15, and it cannot keep up with the speed of the oil flowing out of the compressor 10 and stored in the oil separator 11. Moreover, the circulation of oil through the main circuit R reduces the concentration of refrigerant in the main circuit R, which is a factor that reduces efficiency.

[0050] By performing an oil extraction operation using the pressure boosting mechanism 19, excess oil in the oil storage section 104 can be extracted and directly stored in the accumulator 15. This quickly eliminates excess oil in the compressor 10 and suppresses the performance degradation of the compressor 10 due to excess oil.

[0051] <First Oil Return Operation> Figure 5 is a circuit diagram illustrating the first oil return operation in the refrigeration cycle device 100 according to Embodiment 1. As shown in Figure 5, in the first oil return operation, the control device 20 controls the first on-off valve 194 to be closed and the second on-off valve 195 to be open. The first oil return operation is a direct oil return operation that returns oil directly to the oil storage unit 104, and is an example of an oil return operation performed when the oil level in the oil storage unit 104 is lower than the appropriate oil level A.

[0052] Since the first on-off valve 194 is closed, there is no flow of the heat transfer medium in the first path P1. The heat transfer medium that flows through the second path P2 and into the boosting mechanism 19 from the inlet port 191 flows through the oil port 193 and into the third path P3 and into the oil reservoir 104 of the compressor 10.

[0053] The oil separator 11 is a high-pressure space, while the oil storage section 104 is a low-pressure space. The pressure difference varies from several hundred kPa to several MPa depending on the type of refrigerant. The heat transfer medium containing oil in the oil storage section 104 flows back through the pressure boosting mechanism 19 and into the oil storage section 104. The first oil return operation is effective because it can directly return oil to the oil storage section 104 when the oil level in the compressor 10 drops, and is therefore fast-acting, for example, when the oil level drops rapidly.

[0054] <Second Oil Return Operation> Figure 6 is a circuit diagram illustrating the second oil return operation in the refrigeration cycle device 100 according to Embodiment 1. As shown in Figure 6, in the second oil return operation, the control device 20 controls the first on-off valve 194 to open and the second on-off valve 195 to close. The second oil return operation is an operation that returns oil to the oil storage section 104 via the accumulator 15, and is another example of an oil return operation that is performed when the oil level in the oil storage section 104 is lower than the appropriate oil level A.

[0055] Since the second on-off valve 195 is closed, there is no flow of heat transfer fluid in the third path P3. The heat transfer fluid that flows through the second path P2 and into the boosting mechanism 19 from the inlet port 191 flows through the outlet port 192 and into the first path P1, joining the upstream side of the accumulator 15 in the main circuit R. The heat transfer fluid that has flowed through the main circuit R flows into the compressor 10 from the suction pipe 105 via the accumulator 15.

[0056] This allows the oil in the oil separator 11 to be returned to the compressor 10 via the accumulator 15. In the first oil return operation, refrigerant gas flows in along with the oil, causing the gas to boil and the oil level in the oil reservoir 104 to fluctuate, potentially leading to gas being drawn in by the oil pump 103a. However, this possibility can be eliminated in the second oil return operation. The system should be configured to allow at least one of the first and second oil return operations, but it is preferable to have a system that allows both. For example, the system should be configured to switch between the first and second oil return operations depending on the situation, such as the oil level in the oil reservoir 104.

[0057] <Modified Example> Figure 7 is a schematic partial cross-sectional view of the compressor 10 of the refrigeration cycle device 100 according to a modified example of Embodiment 1. As shown in Figure 7, a float-type sensor 22 may be provided as the oil level height measuring means 17, and the height of the oil level in the oil storage section 104 may be measured by the float-type sensor 22.

[0058] The float-type sensor 22 includes a shaft 222 with one end fixed, an angle sensor 224 attached to one end of the shaft 222, and a float 223 attached to the other end of the shaft 222. The shaft 222 is rotatable about the angle sensor 224 as its axis. The angle sensor 224 measures, for example, the angle between the direction in which the shaft 222 extends and the horizontal direction.

[0059] The float-type sensor 22 notifies the control device 20 of the angle measured by the angle sensor 224. The control device 20 measures the height of the oil level based on the angle. For example, when the oil level in the oil reservoir container 16 is low, the float 223 descends, so the angle between the shaft 222 and the horizontal direction, as measured by the angle sensor 224, decreases. On the other hand, when the oil level is high, the float 223 rises, so the angle between the shaft 222 and the horizontal direction, as measured by the angle sensor 224, increases.

[0060] The float-type sensor 22 may also be configured to measure the oil level based on the angle measured by the angle sensor 224 and notify the control device 20 of the measured oil level.

[0061] As described above, in the refrigeration cycle device 100 according to Embodiment 1, the oil from the compressor 10 is drawn in through the oil port 193 by the driving force of the heat transfer medium flowing in from the inlet port 191 of the pressure boosting mechanism 19 and flows out from the outlet port 192. Therefore, even if the compressor 10 has a low-pressure shell type configuration, it is possible to extract oil directly from the compressor 10, and the amount of oil sealed in the compressor 10 can be kept at an appropriate level. This suppresses the increase in losses due to oil agitation and also suppresses the increase in the amount of oil removed from the compressor 10. Furthermore, since the oil extracted from the compressor 10 does not come into contact with the low-temperature refrigerant flowing into the suction piping, losses due to suction heating can be suppressed.

[0062] Furthermore, an accumulator 15 is connected between the evaporator 14 and the compressor 10. Therefore, the oil sucked in by the pressure boosting mechanism 19 can be guided to and stored in the accumulator 15, which has a larger volume than the oil separator 11.

[0063] Furthermore, the pressure boosting mechanism 19 sucks up oil above a predetermined amount in the oil reservoir 104 formed at the bottom of the shell 110 of the compressor 10, thereby maintaining the oil level in the oil reservoir 104 appropriately.

[0064] Furthermore, the oil port 193 of the pressure boosting mechanism 19 is connected to the inlet 104a via the third path P3. Therefore, the amount of oil in the oil reservoir 104 is maintained at an amount that is necessary for supplying oil to the sliding parts of the compressor 10, and that suppresses oil agitation loss caused by the rotating part of the motor 101 being immersed in oil.

[0065] Furthermore, the system includes an oil separator 11 to which the heat transfer medium branches off before flowing into the condenser 12. In the oil separator 11, the gaseous refrigerant mixed with the separated oil flows into the boosting mechanism 19, allowing the driving force of the high-pressure refrigerant to be effectively utilized to draw in the oil.

[0066] Furthermore, the control device 20 controls the first on-off valve 194 and the second on-off valve 195 of the pressure boosting mechanism 19, thereby enabling oil extraction when the oil volume is high and oil return operation when the oil volume is low, and adjusting the oil volume to an appropriate level.

[0067] Furthermore, the flow rate adjustment device 18, located upstream of the inlet port 191, allows for the bypassing of a quantity of gaseous refrigerant according to the load conditions. For example, this can increase the flow rate of refrigerant to the main circuit R to which the indoor unit is connected, thereby improving energy efficiency.

[0068] 10 Compressor, 11 Oil separator, 12 Condenser, 13 Pressure reducing device, 14 Evaporator, 15 Accumulator, 16 Oil reservoir, 17 Oil level measuring means, 18 Flow rate adjustment device, 19 Pressure boosting mechanism, 20 Control device, 22 Float type sensor, 100 Refrigeration cycle device, 100a Piping, 101 Motor, 101a Stator, 101b Rotor, 102 Compression mechanism, 103 Crankshaft, 103a Oil pump, 104 Oil reservoir, 104a Inlet, 105 Suction pipe, 106 Discharge pipe, 110 Shell, 111 Inlet, 112 Outlet, 113 Oil return port, 191 Inlet port, 192 Outlet port, 193 Oil port, 194 First on-off valve, 195 Second on-off valve, 222 Shaft, 223 float, 224 angle sensor, A proper oil level, H high pressure atmosphere, L low pressure atmosphere, P1 first path, P2 second path, P3 third path, R main circuit.

Claims

1. A refrigeration cycle device comprising a compressor having a low-pressure structure shell in which a motor is installed in a low-pressure atmosphere, a condenser, a pressure reducing device, and an evaporator, wherein the compressor, the condenser, the pressure reducing device, and the evaporator are connected by piping and a heat transfer medium is circulated, and the refrigeration cycle device comprises a pressure boosting mechanism having: an inlet port into which the heat transfer medium branches off and flows in from between the compressor and the condenser; an oil port into which oil drawn from the compressor by the driving force of the heat transfer medium flowing in from the inlet port flows in; and an outlet port into which the oil flowing in from the oil port is mixed with the heat transfer medium and flows out to the suction side of the compressor.

2. The refrigeration cycle apparatus according to claim 1, further comprising an accumulator connected between the evaporator and the compressor, wherein the oil drawn in the pressurization mechanism is guided to the accumulator via the outlet port.

3. The refrigeration cycle apparatus according to claim 1 or 2, wherein an oil reservoir is formed at the bottom of the shell of the compressor, and the boosting mechanism sucks the oil from above an appropriate oil level in the oil reservoir.

4. The refrigeration cycle apparatus according to claim 3, wherein the oil port of the pressure boosting mechanism draws oil from the oil storage section through an inlet located in the oil storage section.

5. The refrigeration cycle apparatus according to any one of claims 1 to 4, further comprising an oil separator provided between the compressor and the condenser, through which the heat transfer medium before it flows into the condenser branches off, wherein a portion of the heat transfer medium separated in the oil separator flows into the boosting mechanism and functions as the driving force for the boosting mechanism.

6. The refrigeration cycle apparatus according to claim 5, further comprising: a first on-off valve provided downstream of the outlet port of the pressure boosting mechanism; a second on-off valve provided between the compressor and the oil port of the pressure boosting mechanism; and a control device for controlling the first on-off valve and the second on-off valve, wherein the control device performs at least one of the following: an oil extraction operation with the first on-off valve open and the second on-off valve open; a first oil return operation with the first on-off valve closed and the second on-off valve open; and a second oil return operation with the first on-off valve open and the second on-off valve closed.

7. The refrigeration cycle apparatus according to any one of claims 1 to 6, further comprising a flow rate adjustment device provided upstream of the inlet port of the pressure boosting mechanism for adjusting the flow rate of the heat transfer medium.

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