Rotary compressor having refrigerating machine oil to be separated into two layers, and refrigeration device comprising same

Abstract

A compressor (11) comprises a compressor casing (11c) and a compression mechanism (60). The compressor casing (11c) accommodates a refrigerant (R) and a refrigerating machine oil (L). The compression mechanism (60) compresses the refrigerant (R). The compression mechanism (60) has a refrigerant outlet (60a) for discharging the compressed refrigerant (R). The refrigerating machine oil (L) mixed with the refrigerant (R) inside the compressor casing (11c) is separated into a first layer (L1) and a second layer (L2). The second layer (L2) is positioned above the first layer (L1). The upper end (H3) of the second layer (L2) is positioned above the refrigerant outlet (60a).

Description

Rotary compressor having refrigerating oil separated into two layers, and refrigeration apparatus including the same

[0001] The present disclosure relates to a casing, a compression mechanism that discharges a gas refrigerant, and a rotary compressor having refrigerating oil separated into two layers within the casing.

[0002] At the lower part of the casing of the rotary compressor disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 11-294334), a liquid separated into two layers is stored. The lower layer of the liquid contains refrigerating oil as a dominant component. The upper layer of the liquid contains not only refrigerating oil but also a large amount of liquid refrigerant. Such two-layer separation is likely to occur when a hydrocarbon is used as the refrigerant and an incompatible oil is used as the refrigerating oil.

[0003] In many rotary compressors, the refrigerating oil stored at the lower part of the casing is pumped up at the lower end of the crankshaft, then passes through an oil supply passage in the crankshaft, and finally is supplied to locations where a plurality of parts are sliding. The sliding locations are inside the compression mechanism or bearings that support the crankshaft.

[0004] When a large amount of liquid refrigerant is present in the refrigerating oil, the liquid refrigerant is supplied to the sliding locations instead of the refrigerating oil. In this case, the lubrication of the sliding locations is inhibited, and there is a risk of causing wear or damage to the parts. In order to suppress wear or damage of the parts, it is preferable that the liquid refrigerant mixed in the refrigerating oil is removed from the refrigerating oil.

[0005] The rotary compressor of the first aspect includes a casing and a compression mechanism. The casing houses a refrigerant and refrigerating oil. The compression mechanism is for compressing the refrigerant. The compression mechanism has a refrigerant outlet for discharging the compressed refrigerant. The refrigerating oil mixed with the refrigerant within the casing is separated into a first layer and a second layer. The second layer is located above the first layer. The upper end of the second layer is located above the refrigerant outlet.

[0006] With this configuration, the gaseous refrigerant exiting the refrigerant outlet is injected into the refrigeration oil, thereby promoting the vaporization of at least the liquid refrigerant contained in the second layer. Therefore, the phenomenon of a large amount of liquid refrigerant remaining mixed in with the refrigeration oil can be suppressed.

[0007] The rotary compressor in the second view is the rotary compressor in the first view, wherein the upper end of the first layer is located below the refrigerant outlet.

[0008] In this configuration, the gaseous refrigerant exiting the refrigerant outlet is not blown into the first layer, which has a lower proportion of liquid refrigerant and a higher proportion of refrigerant oil. Therefore, foaming of the refrigerant oil is suppressed, preventing mist-like refrigerant oil from being discharged to the outside of the rotary compressor along with the refrigerant.

[0009] A rotary compressor in the third view is a rotary compressor in the first or second view, wherein the compression mechanism includes a cylinder, a head member that houses the refrigerant together with the cylinder, and a piston that moves relative to the cylinder. The refrigerant outlet is a discharge port provided in the head member for discharging the refrigerant.

[0010] In this configuration, the refrigerant outlet is the discharge port of the head component. Therefore, the refrigerant discharged from the discharge port is blown into the refrigerant oil, which promotes the vaporization of the liquid refrigerant contained in the refrigerant oil.

[0011] A rotary compressor in the fourth aspect is a rotary compressor in the first or second aspect, wherein the compression mechanism comprises a cylinder, a head member that houses the refrigerant together with the cylinder, a piston that moves relative to the cylinder, and a muffler that reduces the noise emitted from the refrigerant compressed by the piston. The refrigerant outlet is an opening provided in the muffler for discharging the refrigerant.

[0012] In this configuration, the refrigerant outlet is the opening of the muffler. Therefore, the refrigerant discharged from the opening is blown into the refrigerant oil, which promotes the vaporization of the liquid refrigerant contained in the refrigerant oil.

[0013] A rotary compressor in the fifth aspect is a rotary compressor in any one of the first to fourth aspects, wherein the compression mechanism comprises a first compression element having a first cylinder, and a second compression element positioned above the first compression element and having a second cylinder. The refrigerant outlet belongs to the second compression element.

[0014] In this configuration, the refrigerant outlet belongs to the second compression element. Therefore, the refrigerant discharged from the refrigerant outlet located in the second compression element is blown into the refrigerant oil, thereby promoting the vaporization of the liquid refrigerant contained in the refrigerant oil.

[0015] A rotary compressor in the sixth aspect is a rotary compressor in any one of the first to fourth aspects, wherein the compression mechanism comprises a first compression element having a first cylinder, and a second compression element positioned above the first compression element and having a second cylinder. The refrigerant outlet belongs to the first compression element.

[0016] In this configuration, the refrigerant outlet belongs to the first compression element. Therefore, the refrigerant discharged from the refrigerant outlet provided in the first compression element is blown into the refrigerant oil, thereby promoting the vaporization of the liquid refrigerant contained in the refrigerant oil.

[0017] The rotary compressor of the seventh aspect is a rotary compressor of any one of the first to sixth aspects, further comprising a crankshaft, a bearing, and an oil supply passage. The crankshaft drives the compression mechanism. The bearing rotatably supports the crankshaft. The oil supply passage is for supplying a portion of the first or second layer of refrigerant oil to the compression mechanism or the bearing.

[0018] With this configuration, the liquid refrigerant contained in the refrigerant oil entering the fuel passage is promoted to vaporize. Therefore, it is possible to suppress the intrusion of liquid refrigerant into the fuel passage, and consequently reduce seizure of the compression mechanism or bearings.

[0019] The rotary compressor of the eighth perspective is a rotary compressor of any one of the first to seventh perspectives, wherein both the first and second layers contain refrigerant oil and refrigerant. The weight ratio of refrigerant oil in the first layer is greater than the weight ratio of refrigerant oil in the second layer.

[0020] In this configuration, both the first and second layers are mixtures of refrigerant oil and liquid refrigerant components, with the refrigerant oil, which contains a large amount of the lighter liquid refrigerant, positioned above as the first layer. Therefore, by blowing gaseous refrigerant into at least the first layer, the vaporization of a large amount of liquid refrigerant can be promoted.

[0021] The rotary compressor of the ninth perspective is a rotary compressor of any one of the first to eighth perspectives, wherein the refrigerant is a natural refrigerant.

[0022] In this configuration, the refrigerant is a natural refrigerant. Therefore, the refrigerant has little impact on the environment.

[0023] The rotary compressor of the tenth aspect is a rotary compressor of any one of the first to ninth aspects, wherein the refrigerant is a single refrigerant consisting of hydrocarbons, or a mixed refrigerant containing hydrocarbons.

[0024] In this configuration, the refrigerant is a hydrocarbon such as propane, which readily dissolves in the refrigeration oil in liquid form. Even in this case, the vaporization of the liquid refrigerant is promoted, which can suppress the phenomenon of a large amount of liquid refrigerant remaining mixed in with the refrigeration oil.

[0025] The rotary compressor of the eleventh perspective is a rotary compressor of any one of the first to tenth perspectives, and the refrigerant is propane.

[0026] In this configuration, the refrigerant is propane, and its liquid component is easily mixed with the specified refrigerant oil. In this case, the vaporization of the liquid component is promoted.

[0027] The rotary compressor of the twelfth perspective is a rotary compressor of any one of the first to eleventh perspectives, wherein the refrigerant oil is an incompatible oil that is incompatible with the refrigerant.

[0028] In this configuration, the refrigeration oil is an immiscible oil such as mono-ol type PAG oil. Therefore, the refrigeration oil is prone to separating into a first layer and a second layer. Even in this case, it is possible to suppress the intrusion of liquid refrigerant, which is largely contained in the second layer, into the compressor's oil supply passage, thereby reducing bearing seizure.

[0029] The rotary compressor of the 13th aspect is a rotary compressor of any one of the 12th aspects of the first aspect, wherein the refrigerant oil contains any of polyalkylene glycol, polyvinyl ether, or polyol ester.

[0030] In this configuration, the refrigerant oil is easily mixed with the liquid component of the specified refrigerant. In this case, the vaporization of the liquid component is promoted.

[0031] The rotary compressor of the 14th aspect is a rotary compressor of any one of the 13th aspects of the 1st aspect, wherein the refrigerant oil is monoal type polyalkylene glycol.

[0032] In this configuration, the refrigerant oil is a monoal type polyalkylene glycol, which is readily mixed with the liquid component of the specified refrigerant. In this case, the vaporization of the liquid component is promoted.

[0033] The rotary compressor of the 15th perspective is a rotary compressor of any one of the 14th perspectives, wherein the refrigerant oil separates into a first layer and a second layer due to the compression mechanism being stopped for 5 hours or more, or due to the refrigerant oil becoming cold below zero degrees Celsius.

[0034] With this configuration, separation of the refrigerant oil is caused by prolonged shutdown of the compression mechanism or a drop in the temperature of the refrigerant oil. Therefore, even when starting the rotary compressor, for example, on a winter morning, it is possible to suppress the intrusion of liquid refrigerant, which is largely contained in the second layer, into the compressor's oil supply passage, thereby reducing bearing seizure.

[0035] The refrigeration system of the 16th aspect comprises one rotary compressor from either the 1st aspect or the 15th aspect.

[0036] This configuration reduces bearing seizure in compressors installed in refrigeration systems.

[0037] This is a schematic diagram showing the configuration of a refrigeration system 100 according to one embodiment. This is a cross-sectional view of the compressor 11 and the accumulator 16. This is a cross-sectional view of the compressor 11. This is a graph showing the conditions under which two-layer separation occurs. This is a cross-sectional view of the compressor 11 according to modified example A. This is a cross-sectional view of the compressor 11 according to modified example B. This is a cross-sectional view of the compressor 11 according to modified example C.

[0038] (1) Overall Configuration Diagram 1 shows the configuration of a refrigeration system 100 according to one embodiment of the present disclosure. The refrigeration system 100 is for providing cold heat or hot heat to the user. The refrigeration system 100 is configured as a product such as an air conditioner, refrigerator, freezer, floor heating system, or water heater. The refrigeration system 100 has a heat source unit 10, a utilization unit 20, a group of connecting pipes 30, and a communication line 35. A refrigerant R circulates in the refrigerant circuit, which is composed of the heat source unit 10, the utilization unit 20, and the group of connecting pipes 30.

[0039] (2) Detailed Configuration (2-1) Heat Source Unit 10 The heat source unit 10 is for obtaining cold or hot energy from a heat source and supplying it to the refrigerant R. The heat source unit 10 includes a heat source casing 10a, a compressor 11, a four-way switching valve 12, a heat source heat exchanger 13, a heat source fan 14, a heat source expansion valve 15, an accumulator 16, a liquid shut-off valve 17, a gas shut-off valve 18, and a heat source control unit 19.

[0040] (2-1-1) Heat source casing 10a The heat source casing 10a houses the components of the heat source unit 10. When the heat source is air, the heat source casing 10a is provided with an opening to allow air to pass through.

[0041] (2-1-2) Compressor 11 The compressor 11 compresses the refrigerant R. The compressor 11 has an intake pipe 11a and a discharge pipe 11b. The refrigerant R in a low-pressure gaseous state is drawn in through the intake pipe 11a, compressed inside the compressor 11 to become the refrigerant R in a high-pressure gaseous state, and then discharged through the discharge pipe 11b.

[0042] (2-1-3) Four-way switching valve 12 The four-way switching valve 12 is provided when the refrigeration device 100 performs both cold heat utilization operation and warm heat utilization operation. The cold heat utilization operation is an operation that provides cold heat to the user. The warm heat utilization operation is an operation that provides warm heat to the user.

[0043] When the refrigeration device 100 performs the cold heat utilization operation, the four-way switching valve 12 forms the connection shown by the solid line in FIG. 1. At this time, the refrigerant R circulates in the refrigerant circuit in the direction indicated by the arrow CO.

[0044] When the refrigeration device 100 performs the warm heat utilization operation, the four-way switching valve 12 forms the connection shown by the broken line in FIG. 1. At this time, the refrigerant R circulates in the refrigerant circuit in the direction indicated by the arrow HO.

[0045] (2-1-4) Heat source heat exchanger 13 The heat source heat exchanger 13 obtains warm heat or cold heat from the heat source by performing heat exchange between the heat source and the refrigerant R. When the heat source is air, the air passes through the heat source heat exchanger 13. When the refrigeration device 100 performs the cold heat utilization operation, the heat source heat exchanger 13 functions as a condenser or radiator of the refrigerant R. When the refrigeration device 100 performs the warm heat utilization operation, the heat source heat exchanger 13 functions as an evaporator or heat absorber of the refrigerant R.

[0046] (2-1-5) Heat source fan 14 The heat source fan 14 is provided when the heat source is air. The heat source fan 14 moves the air so that the air passes through the heat source heat exchanger 13 in order to promote heat exchange between the air and the refrigerant R. The heat source fan 14 has heat source fan blades 14b for generating an air flow and a heat source fan motor 14m for rotating the heat source fan blades 14b.

[0047] (2-1-6) Heat source expansion valve 15 The heat source expansion valve 15 reduces the pressure of the refrigerant R and adjusts the circulation amount of the refrigerant R. The heat source expansion valve 15 is constituted by an electric valve whose opening degree can be adjusted. By being controlled so that the opening degree becomes larger, the heat source expansion valve 15 can increase the circulation amount of the refrigerant R. By being controlled so that the opening degree becomes smaller, the heat source expansion valve 15 can lower the pressure of the refrigerant R.

[0048] (2-1-7) Accumulator 16 The accumulator 16 separates and stores the liquid refrigerant component contained in the gaseous refrigerant R. This suppresses the liquid refrigerant from being sucked from the suction pipe 11a into the compressor 11, and reduces the failure of the compressor 11.

[0049] The accumulator 16 has an inlet pipe 16a and an outlet pipe 16b. The refrigerant R flowing in from the inlet pipe 16a is dominated by the gaseous component, but may also contain a liquid component. The accumulator 16 discharges the gaseous component from the outlet pipe 16b while storing the liquid component in the casing.

[0050] (2-1-8) Liquid shut-off valve 17, gas shut-off valve 18 The liquid shut-off valve 17 and the gas shut-off valve 18 are valves that can be manually opened and closed. The liquid shut-off valve 17 and the gas shut-off valve 18 are opened and closed by the installer of the refrigeration device 100 when connecting or disconnecting the communication pipe group 30.

[0051] (2-1-9) Heat source control unit 19 The heat source control unit 19 receives signals from the sensor group mounted on the heat source unit 10 and controls the actuator group mounted on the heat source unit 10. The sensor group includes a refrigerant pressure sensor and a temperature sensor (not shown). The actuator group includes the heat source fan motor 14m.

[0052] (2-2) Usage unit 20 The usage unit 20 is for providing the user with the cooling or heating carried by the refrigerant R. The usage unit 20 has a usage casing 20a, a usage heat exchanger 23, a usage fan 24, and a usage control unit 29.

[0053] (2-2-1) Usage casing 20a The usage casing 20a houses the components of the usage unit 20. When the refrigeration device 100 is an air conditioner, the usage casing 20a is provided with an opening for air to pass through.

[0054] (2-2-2) Heat Exchanger 23 The heat exchanger 23 provides heat or cold to the user by exchanging heat between the medium and the refrigerant R. When the refrigeration system 100 is an air conditioning system, the air, which is the medium, passes through the heat exchanger 23. When the refrigeration system 100 is operating in a cold energy utilization operation, the heat exchanger 23 functions as an evaporator or heat absorber for the refrigerant R. When the refrigeration system 100 is operating in a hot energy utilization operation, the heat exchanger 23 functions as a condenser or heat radiator for the refrigerant R.

[0055] (2-2-3) Utilization fan 24 The utilization fan 24 is provided when providing cooling or heating to the user via air. The utilization fan 24 moves air so that it passes through the utilization heat exchanger 23 in order to promote heat exchange between the air and the refrigerant R. The utilization fan 24 has utilization fan blades 24b for generating airflow and utilization fan motor 24m for rotating the utilization fan blades 24b.

[0056] (2-2-4) Utilization Control Unit 29 The utilization control unit 29 receives signals from the sensor group mounted on the utilization unit 20 and controls the actuator group mounted on the utilization unit 20. The sensor group includes a refrigerant pressure sensor and a temperature sensor (not shown). The actuator group includes a utilization fan motor 24m.

[0057] (2-3) Connecting piping group 30 The connecting piping group 30 is a piping that constitutes part of the refrigerant circuit and connects the heat source unit 10 and the utilization unit 20. The connecting piping group 30 has liquid connecting piping 31 and gas connecting piping 32. Liquid connecting piping 31 mainly guides the refrigerant R in a liquid state or a gas-liquid two-phase state and connects the liquid shut-off valve 17 and the utilization heat exchanger 23. Gas connecting piping 32 mainly guides the refrigerant R in a high-pressure gas state or a low-pressure gas state and connects the gas shut-off valve 18 and the utilization heat exchanger 23.

[0058] (2-4) Communication line 35 The communication line 35 electrically connects the heat source control unit 19 and the utilization control unit 29. The heat source control unit 19 and the utilization control unit 29 can communicate with each other via the communication line 35. By communicating using the communication line 35, the heat source control unit 19 and the utilization control unit 29 cooperate to form the device control unit 9.

[0059] (3) Overall Operation (3-1) Cooling and Heat Utilization Operation The compressor 11 draws in low-pressure gaseous refrigerant from the suction pipe 11a and discharges high-pressure gaseous refrigerant from the discharge pipe 11b. The high-pressure gaseous refrigerant reaches the heat source heat exchanger 13 via the four-way switching valve 12. In the heat source heat exchanger 13, the high-pressure gaseous refrigerant condenses by acquiring cooling from the heat source and becomes high-pressure liquid refrigerant. The high-pressure liquid refrigerant leaves the heat source heat exchanger 13 and reaches the heat source expansion valve 15. As the high-pressure liquid refrigerant passes through the heat source expansion valve 15, it is depressurized and becomes a gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant reaches the utilization heat exchanger 23 via the liquid shut-off valve 17 and the liquid connecting pipe 31. In the utilization heat exchanger 23, the gas-liquid two-phase refrigerant provides cooling to the user in the process of evaporating and becoming a low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant enters the accumulator 16 through the inlet pipe 16a via the gas communication pipe 32, the gas shut-off valve 18, and the four-way switching valve 12. In the accumulator 16, the liquid components mixed in with the low-pressure gaseous refrigerant are separated. After that, the low-pressure gaseous refrigerant exits the accumulator 16 through the outlet pipe 16b and is drawn into the compressor 11 through the suction pipe 11a.

[0060] (3-2) The thermal energy utilization compressor 11 draws in low-pressure gaseous refrigerant from the suction pipe 11a and discharges high-pressure gaseous refrigerant from the discharge pipe 11b. The high-pressure gaseous refrigerant reaches the utilization heat exchanger 23 via the four-way switching valve 12, the gas shut-off valve 18, and the gas connecting pipe 32. In the utilization heat exchanger 23, the high-pressure gaseous refrigerant provides heat to the user in the process of condensing into high-pressure liquid refrigerant. The high-pressure liquid refrigerant leaves the utilization heat exchanger 23 and reaches the heat source expansion valve 15 via the liquid connecting pipe 31 and the liquid shut-off valve 17. The high-pressure liquid refrigerant is depressurized as it passes through the heat source expansion valve 15 and becomes a gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant reaches the heat source heat exchanger 13. In the heat source heat exchanger 13, the gas-liquid two-phase refrigerant evaporates by acquiring heat from the heat source and becomes low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant enters the accumulator 16 through the inlet pipe 16a via the four-way switching valve 12. In the accumulator 16, the liquid components mixed in with the low-pressure gaseous refrigerant are separated. After that, the low-pressure gaseous refrigerant exits the accumulator 16 through the outlet pipe 16b and is drawn into the compressor 11 through the suction pipe 11a.

[0061] (4) Detailed configuration diagram 2 of the compressor 11 shows a cross-section of the compressor 11 and the accumulator 16. The compressor 11 is a rotary compressor. The compressor 11 has a compressor casing 11c, a motor 40, a crankshaft 50, and a compression mechanism 60.

[0062] (4-1) Compressor casing 11c The compressor casing 11c houses the components of the compressor 11. The compressor casing 11c is fitted with an intake pipe 11a and a discharge pipe 11b. The intake pipe 11a is connected to the outlet pipe 16b of the accumulator 16.

[0063] (4-2) Motor 40 The motor 40 receives power and generates power for compressing the refrigerant R. The motor 40 has a stator 41 and a rotor 42. The stator 41 is a cylindrical member and is fixed to the compressor casing 11c. The stator 41 has coils (not shown). The coils receive power and generate an alternating magnetic field. The rotor 42 is rotatably positioned in the central cavity of the stator 41. The rotor 42 has permanent magnets (not shown). The rotor 42 rotates as the permanent magnets interact with the alternating magnetic field.

[0064] (4-3) Crankshaft 50 The crankshaft 50 drives the compression mechanism 60 by transmitting power from the motor 40 to the compression mechanism 60. The crankshaft 50 has a main shaft portion 51 that is concentric with the rotation axis RA, and a first eccentric portion 52 and a second eccentric portion 53 that are offset from the rotation axis RA. The main shaft portion 51 is fixed to the rotor 42. The first eccentric portion 52 and the second eccentric portion 53 are located inside the compression mechanism 60.

[0065] (4-4) Compression mechanism 60 The compression mechanism 60 is for compressing the refrigerant R. The compression mechanism 60 is a two-cylinder rotary compression mechanism and has a first compression element 61 and a second compression element 62. The first compression element 61 has a first cylinder 611, a first piston 612, a middle plate 63, a first head 64, and a first muffler 66. The second compression element 62 is positioned higher than the first compression element 61. The second compression element 62 has a second cylinder 621, a second piston 622, a middle plate 63, a second head 65, and a second muffler 67. The middle plate 63 belongs to both the first compression element 61 and the second compression element 62.

[0066] (4-4-1) First Cylinder 611 and First Piston 612 The first cylinder 611 has a circular cavity in which the first piston 612 is located. The first piston 612 also has a circular cavity in which the first eccentric portion 52 is located. The upper part of the cavity of the first cylinder 611 is closed by a middle plate 63. The lower part of the cavity of the first cylinder 611 is closed by a first head 64. The first cylinder 611, the first piston 612, the middle plate 63, and the first head 64 work together to define the first compression chamber 613. The first compression chamber 613 contains the refrigerant R. When the crankshaft 50 rotates, the first piston 612 moves relative to the first cylinder 611. This changes the volume of the first compression chamber 613 and compresses the refrigerant R.

[0067] (4-4-2) Second cylinder 621 and second piston 622 The second cylinder 621 has a circular cavity in which the second piston 622 is located. The second piston 622 also has a circular cavity in which the second eccentric portion 53 is located. The upper part of the cavity of the second cylinder 621 is closed by the second head 65. The lower part of the cavity of the second cylinder 621 is closed by the middle plate 63. The second cylinder 621, the second piston 622, the second head 65, and the middle plate 63 work together to define the second compression chamber 623. The second compression chamber 623 contains the refrigerant R. When the crankshaft 50 rotates, the second piston 622 moves relative to the second cylinder 621. This changes the volume of the second compression chamber 623 and compresses the refrigerant R.

[0068] (4-4-3) Middle plate 63 The middle plate 63 is positioned to separate the first compression chamber 613 and the second compression chamber 623. The middle plate 63 defines a part of the interface between the first compression chamber 613 and the second compression chamber 623.

[0069] (4-4-4) First head 64 The first head 64 is in contact with the first cylinder 611 so as to define a portion of the interface of the first compression chamber 613. The first head 64 holds the first bearing 55 (see Figure 3). The first bearing 55 rotatably supports a portion of the main shaft portion 51 of the crankshaft 50.

[0070] (4-4-5) Second head 65 The second head 65 is in contact with the second cylinder 621 so as to define a portion of the interface of the second compression chamber 623. The second head 65 holds the second bearing 56 (see Figure 3). The second bearing 56 rotatably supports a portion of the main shaft portion 51 of the crankshaft 50.

[0071] (4-4-6) First muffler 66 The first muffler 66 is for reducing the noise emitted from the refrigerant R compressed by the first piston 612 in the first compression element 61. The first muffler 66 is attached to the first head 64. The first muffler 66 works in cooperation with the first head 64 to form the first muffler space M1. The refrigerant R discharged from the first compression chamber 613 flows into the first muffler space M1, thereby reducing noise.

[0072] (4-4-7) Second muffler 67 The second muffler 67 is for reducing the noise emitted from the refrigerant R compressed by the second piston 622 in the second compression element 62. The second muffler 67 is attached to the second head 65. The second muffler 67 works in cooperation with the second head 65 to form the second muffler space M2. The refrigerant R discharged from the second compression chamber 623 flows into the second muffler space M2, thereby reducing noise.

[0073] The first muffler space M1 and the second muffler space M2 may be connected by providing a refrigerant passage that penetrates the first head 64, the first cylinder 611, the middle plate 63, the second cylinder 621, and the second head 65.

[0074] (5) Two-layer separation of refrigerant oil L (5-1) Structure of the area around the compression mechanism 60 Figure 3 is an enlarged view of the area around the compression mechanism 60 in the compressor 11. The internal space 11d of the compressor casing 11c contains the refrigerant R and refrigerant oil L. Below the internal space 11d, an oil reservoir 11e is provided for storing the refrigerant oil L. The refrigerant oil L is used to lubricate the parts where multiple components constituting the compressor 11 slide against each other. Specifically, the refrigerant oil L is supplied to the inside of the compression mechanism 60, the first bearing 55, the second bearing 56, etc.

[0075] An oil supply passage 54 is provided inside the crankshaft 50. The oil supply passage 54 is for supplying a portion of the refrigerant oil L to sliding parts such as the compression mechanism 60, the first bearing 55, and the second bearing 56. When the motor 40 rotates the crankshaft 50, the refrigerant oil L near the lower end of the crankshaft 50 is pumped up to the oil supply passage 54 and then supplied to the sliding parts.

[0076] The first head 64 is provided with a first discharge port 641. The first discharge port 641 is an opening that discharges the refrigerant R from the first compression chamber 613 (see Figure 2) into the first muffler space M1. The first discharge port 641 is provided with a first discharge valve 642 that opens and closes according to the pressure of the refrigerant R.

[0077] The second head 65 is provided with a second discharge port 651. The second discharge port 651 is an opening that discharges the refrigerant R from the second compression chamber 623 (see Figure 2) into the second muffler space M2. The second discharge port 651 is provided with a second discharge valve 652 that opens and closes according to the pressure of the refrigerant R.

[0078] (5-2) Refrigerant R and Refrigerant Oil L Refrigerant R is a natural refrigerant. For example, refrigerant R is a single refrigerant consisting of hydrocarbons, or a mixed refrigerant containing hydrocarbons. Furthermore, the hydrocarbon that constitutes or is contained in refrigerant R may be propane (R290).

[0079] The refrigerant oil L is an immiscible oil that is incompatible with the refrigerant R. Propane, the refrigerant R, generally dissolves easily in the refrigerant oil L, and is prone to causing foaming of the refrigerant oil L when the compressor 11 is started. For this reason, it is desirable to use an immiscible oil as the refrigerant oil L in order to suppress foaming of the refrigerant oil L caused by the dissolution of the refrigerant R. As the immiscible refrigerant oil L, one can be selected that contains any of polyalkylene glycol, polyvinyl ether, or polyol ester. Furthermore, the refrigerant oil L may be a monool-type polyalkylene glycol. The molecular weight of the refrigerant oil L is preferably 1000 or more and 1800 or less. This suppresses the dissolution of the refrigerant R into the refrigerant oil L.

[0080] The viscosity of the refrigeration oil L is preferably 5.0 mPa·s or higher. This suppresses wear on the sliding parts to which the refrigeration oil L is supplied.

[0081] (5-3) The two-layer separated refrigerant oil L is supplied from the oil reservoir 11e to the sliding part and falls back into the oil reservoir 11e. In the process, the refrigerant oil L collides with the refrigerant R that is swirling around inside the compressor casing 11c. In this way, the refrigerant oil L and the refrigerant R, which are moving violently inside the compressor casing 11c, mix with each other.

[0082] When the refrigerant R and refrigerant oil L are of the types described above, the refrigerant oil L mixed with the refrigerant R in the compressor casing 11c is easily separated into a lower first layer L1 and an upper second layer L2. Both the first layer L1, which has a relatively high specific gravity, and the second layer L2, which has a relatively low specific gravity, contain refrigerant oil L and liquid refrigerant R. The weight ratio of refrigerant oil L to the first layer L1 is greater than the weight ratio of refrigerant oil L to the second layer L2. The weight ratio of refrigerant R to the first layer L1 is less than the weight ratio of refrigerant R to the second layer L2. Note that the term "weight ratio" used in this specification may also be expressed as "concentration."

[0083] For example, in the first layer L1, which contains a relatively large amount of refrigerant oil L, the weight ratio of refrigerant R is 55% by weight and the weight ratio of refrigerant oil L is 45% by weight. On the other hand, in the second layer L2, which contains a relatively large amount of refrigerant R, the weight ratio of refrigerant R is 95% by weight and the weight ratio of refrigerant oil L is 5% by weight.

[0084] To give another example, in the first layer L1, which contains a relatively large amount of refrigerant oil L, the weight ratio of refrigerant oil L exceeds 50% by weight, and the weight ratio of refrigerant R is less than 50% by weight. On the other hand, in the second layer L2, which contains a relatively large amount of refrigerant R, the weight ratio of refrigerant oil L is less than 50% by weight, and the weight ratio of refrigerant R exceeds 50% by weight.

[0085] In Figure 3, the lower end H0 of the first layer L1 is located at the bottom of the oil reservoir 11e. The upper end H2 of the first layer L1 is also the separation interface between the first layer L1 and the second layer L2, and is located higher than the lower end H0 of the first layer L1. The upper end H3 of the second layer L2 is also the liquid level of the refrigeration oil L, and is located higher than the upper end H2 of the first layer L1.

[0086] Such two-layer separation of refrigerant oil L typically occurs when the compression mechanism 60 is stopped for a long period of time, or when the temperature of the refrigerant oil L drops low. For example, if the compression mechanism 60 has been stopped for more than 5 hours, or if the refrigerant oil L is at a low temperature of below zero degrees Celsius, such as on a winter morning, the refrigerant oil L is likely to separate into a first layer L1 and a second layer L2.

[0087] Figure 4 is a graph showing the conditions under which two-phase separation occurs. The vertical and horizontal axes of this graph represent the state of the mixture of refrigerant oil L and refrigerant R stored in the oil reservoir 11e of the compressor 11. Refrigerant R is propane. Refrigerant oil L is monool-type polyalkylene glycol. The horizontal axis shows the weight ratio of refrigerant oil L in the mixture. The vertical axis represents the temperature of the mixture. Region A shows the dissolution region where two-phase separation does not occur. Region B shows the separation region where two-phase separation occurs. For example, if the weight ratio of refrigerant R in the mixture is 55% by weight, two-phase separation may not occur during the daytime when the mixture temperature is 15°C, but may occur in the early morning when the mixture temperature is minus 10°C.

[0088] (5-4) Refrigerant outlet 60a The compression mechanism 60 in Figure 3 is for compressing the refrigerant R and has a refrigerant outlet 60a for discharging the compressed refrigerant R. In this embodiment, the refrigerant outlet 60a is an opening 671 provided in the second muffler 67 for discharging the refrigerant R in a high-pressure gas state. Therefore, the refrigerant outlet 60a belongs to the second compression element 62.

[0089] The amount of refrigerant oil L contained in the compressor 11 is adjusted so that the upper end H3 of the second layer L2 is above the height H1 of the refrigerant outlet 60a. In addition, the amount of refrigerant oil L is adjusted so that the upper end H2 of the first layer L1 is below the height H1 of the refrigerant outlet 60a. The manufacturer of the compressor 11 can set the relationship between the height of the interface of the first layer L1 or the second layer L2 and the height of the mechanical components, including the refrigerant outlet 60a, for example, by adjusting the total amount of refrigerant oil L or by adjusting the design dimensions of each component of the compressor 11.

[0090] (6) Features (6-1) Since the upper end H3 of the second layer L2 is located above the refrigerant outlet 60a, the gaseous refrigerant R coming out of the refrigerant outlet 60a is blown into the refrigerant oil L. This promotes the vaporization of at least the liquid refrigerant R contained in the second layer L2. Therefore, it is possible to suppress the phenomenon in which a large amount of liquid refrigerant R remains mixed in the refrigerant oil L.

[0091] Furthermore, both the first layer L1 and the second layer L2 are mixtures of refrigerant oil L and liquid refrigerant R, with the second layer L2, which contains a larger amount of the lighter refrigerant R, located on top. Therefore, by blowing gaseous refrigerant R into at least the second layer L2, the vaporization of liquid refrigerant R can be efficiently promoted.

[0092] (6-2) Since the upper end H2 of the first layer L1 is located below the refrigerant outlet 60a, the gaseous refrigerant R coming out of the refrigerant outlet 60a is not blown into the first layer L1, which has a relatively small proportion of refrigerant R and a relatively large proportion of refrigerant oil L. Therefore, foaming of the refrigerant oil L is suppressed, and the situation in which mist-like refrigerant oil L is discharged to the outside of the compressor 11 together with the refrigerant R can be suppressed.

[0093] (6-3) The refrigerant outlet 60a is an opening 671 provided in the second muffler 67. Therefore, the gaseous refrigerant R discharged from the opening 671 is blown into the refrigerant oil L, which promotes the vaporization of the liquid refrigerant R contained in the refrigerant oil L.

[0094] (6-4) The refrigerant outlet 60a belongs to the second compression element 62. Since the second compression element 62 is located above the first compression element 61, the refrigerant R discharged from the refrigerant outlet 60a is easily blown into the second layer L2 in the refrigerant oil L. Therefore, the vaporization of the liquid refrigerant R contained in the refrigerant oil L is easily promoted.

[0095] (6-5) Before the refrigerant oil L enters the oil supply passage 54, the liquid refrigerant R contained in the refrigerant oil L is promoted to vaporize. Therefore, the situation in which the refrigerant R enters the oil supply passage 54 can be suppressed, and consequently, seizure, wear, and damage to the compression mechanism 60, the first bearing 55, and the second bearing 56 can be reduced. Consequently, the failure of the refrigeration system 100 can be reduced.

[0096] (6-6) Separation of the refrigerant oil L is caused by the prolonged shutdown of the compression mechanism 60 or a drop in the temperature of the refrigerant oil L. Therefore, even when starting the compressor 11, for example on a winter morning, it is possible to suppress the situation in which the liquid refrigerant R, which is largely contained in the second layer L2, enters the oil supply passage 54 of the compressor 11, thereby reducing seizure, wear, and damage to the compression mechanism 60, the first bearing 55, and the second bearing 56.

[0097] (7) Modified Examples (7-1) Modified Example A In the above embodiment, the refrigerant outlet 60a is an opening 671 provided in the second muffler 67. Alternatively, as shown in Figure 5, the refrigerant outlet 60a may be a second discharge port 651 provided in the second head 65. The refrigerant outlet 60a belongs to the second compression element 62. The upper end H3 of the second layer L2 is located above the refrigerant outlet 60a. The upper end H2 of the first layer L1 is located below the refrigerant outlet 60a.

[0098] In this case as well, since the upper end H3 of the second layer L2 is located above the refrigerant outlet 60a, the gaseous refrigerant R coming out of the refrigerant outlet 60a is blown into the refrigerant oil L. Therefore, the vaporization of at least the liquid refrigerant R contained in the second layer L2 is promoted, and the phenomenon of a large amount of liquid refrigerant R remaining mixed in the refrigerant oil L can be suppressed.

[0099] (7-2) Modification B In the above embodiment, the refrigerant outlet 60a is an opening 671 provided in the second muffler 67. Alternatively, as shown in Figure 6, the refrigerant outlet 60a may be an opening 661 provided in the first muffler 66. The refrigerant outlet 60a belongs to the first compression element 61. The upper end H3 of the second layer L2 is located above the refrigerant outlet 60a. The upper end H2 of the first layer L1 is located below the refrigerant outlet 60a. In this case as well, vaporization of the liquid refrigerant R is promoted.

[0100] (7-3) Modification C In the above embodiment, the refrigerant outlet 60a is an opening 671 provided in the second muffler 67. Alternatively, as shown in Figure 7, the refrigerant outlet 60a may be a first discharge port 641 provided in the first head 64. The refrigerant outlet 60a belongs to the first compression element 61. The upper end H3 of the second layer L2 is located above the refrigerant outlet 60a. The upper end H2 of the first layer L1 is located below the refrigerant outlet 60a. In this case as well, vaporization of the liquid refrigerant R is promoted.

[0101] (7-4) Modification D In the above embodiment, the refrigerant R contains a hydrocarbon, which is a type of natural refrigerant. The hydrocarbon is, for example, propane. Alternatively, the refrigerant R may contain a natural refrigerant other than a hydrocarbon. For example, the refrigerant R may be carbon dioxide, ammonia, or water.

[0102] <Conclusion> The embodiments of this disclosure have been described above, but it should be understood that various modifications to the form and details are possible without departing from the purpose and scope of this disclosure as described in the claims.

[0103] 10: Heat source unit 11: Compressor (rotary compressor) 11c: Compressor casing (casing) 11e: Oil reservoir 20: Utilization unit 30: Connecting piping group 35: Communication line 40: Motor 50: Crankshaft 54: Oil supply passage 55: First bearing (bearing) 56: Second bearing (bearing) 60: Compression mechanism 60a: Refrigerant outlet 61: First compression element 62: Second compression element 63: Middle plate 64: First head (head member) 65: Second head (head member) 66: First muffler (muffler) 67: Second muffler (muffler) 100: Refrigeration device 611: First cylinder (cylinder) 612: First piston (piston) 613: First compression chamber 621: Second cylinder (cylinder) 622: Second piston (piston) 623: Second compression chamber 641: First discharge port (discharge port) 642: First discharge valve 651: Second discharge port (discharge port) 652: Second discharge valve 661: Opening 671: Opening L: Refrigerant oil L1: First layer L2: Second layer R: Refrigerant H0: Lower end of first layer H1: Height of refrigerant outlet H2: Upper end of first layer H3: Upper end of second layer

[0104] Japanese Patent Application Publication No. 11-294334

Claims

1. A rotary compressor (11) comprising: a casing (11c) for housing a refrigerant (R) and refrigerant oil (L); and a compression mechanism (60) for compressing the refrigerant and having a refrigerant outlet (60a) for discharging the compressed refrigerant, wherein the refrigerant oil mixed with the refrigerant in the casing is separated into a first layer (L1) and a second layer (L2) located above the first layer, and the upper end (H3) of the second layer is located above the refrigerant outlet.

2. The rotary compressor according to claim 1, wherein the upper end (H2) of the first layer is located below the refrigerant outlet.

3. The rotary compressor according to claim 1 or claim 2, wherein the compression mechanism comprises cylinders (611, 621), head members (64, 65) that house the refrigerant together with the cylinders, and pistons (612, 622) that move relative to the cylinders, and the refrigerant outlet is a discharge port (641, 651) provided in the head member for discharging the refrigerant.

4. The rotary compressor according to claim 1 or claim 2, wherein the compression mechanism comprises cylinders (611, 621), head members (64, 65) that house the refrigerant together with the cylinders, pistons (612, 622) that move relative to the cylinders, and mufflers (66, 67) that reduce the noise emitted from the refrigerant compressed by the pistons, and the refrigerant outlet is an opening (661, 671) provided in the muffler for discharging the refrigerant.

5. The rotary compressor according to any one of claims 1 to 4, wherein the compression mechanism comprises a first compression element (61) having a first cylinder (611), and a second compression element (62) positioned above the first compression element and having a second cylinder (621), and the refrigerant outlet belongs to the second compression element.

6. The rotary compressor according to any one of claims 1 to 4, wherein the compression mechanism comprises a first compression element (61) having a first cylinder (611), and a second compression element (62) positioned above the first compression element and having a second cylinder (621), and the refrigerant outlet belongs to the first compression element.

7. A rotary compressor according to any one of claims 1 to 6, further comprising: a crankshaft (50) for driving the compression mechanism; bearings (55, 56) for rotatably supporting the crankshaft; and an oil supply passage (54) for supplying a portion of the refrigerant oil from the first or second layer to the compression mechanism or the bearings.

8. The rotary compressor according to any one of claims 1 to 7, wherein both the first layer and the second layer contain the refrigerant oil and the refrigerant, and the weight ratio of the refrigerant oil to the first layer is greater than the weight ratio of the refrigerant oil to the second layer.

9. The rotary compressor according to any one of claims 1 to 8, wherein the refrigerant is a natural refrigerant.

10. The rotary compressor according to any one of claims 1 to 9, wherein the refrigerant is a single refrigerant consisting of hydrocarbons, or a mixed refrigerant containing hydrocarbons.

11. The rotary compressor according to any one of claims 1 to 10, wherein the refrigerant is propane.

12. The rotary compressor according to any one of claims 1 to 11, wherein the refrigeration oil is an incompatible oil that is incompatible with the refrigerant.

13. The rotary compressor according to any one of claims 1 to 12, wherein the refrigeration oil comprises polyalkylene glycol, polyvinyl ether, or polyol ester.

14. The rotary compressor according to any one of claims 1 to 13, wherein the refrigeration oil is a monoal type polyalkylene glycol.

15. The rotary compressor according to any one of claims 1 to 14, wherein the refrigerant oil separates into the first layer and the second layer due to the compression mechanism being stopped for five hours or more, or due to the refrigerant oil becoming colder than zero degrees Celsius.

16. A refrigeration system (100) comprising a rotary compressor according to any one of claims 1 to 15.

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