Screw compressors and refrigeration systems
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- DAIKIN INDUSTRIES LTD
- Filing Date
- 2024-09-18
- Publication Date
- 2026-07-30
Smart Images
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Abstract
Description
Technical Field
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[0001] The present disclosure relates to a screw compressor and a refrigeration device.
Background Art
[0002] Conventionally, a screw compressor for compressing a gas such as a refrigerant has been known (see, for example, Patent Document 1). In the compressor described in Patent Document 1, a motor and a compression rotor of a compression section are horizontally arranged in a casing in order from the suction port side. In such a configuration, in the suction chamber of the casing that sucks a fluid containing gas and lubricating liquid from the outside, a part of the lubricating liquid is separated from the sucked fluid and stored at the bottom of the casing. A part of the lubricating liquid stored at the bottom of the casing is agitated and lifted by the rotation of the rotor of the motor or the compression rotor of the compression section, and is sucked into the compression section together with the sucked fluid.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In response to the increasing demand for replacing gas boilers with heat pump chillers due to international decarbonization efforts and the uncertainty of the energy situation, it is required to expand the operating range of the compressor installed in the heat pump chiller to a region of low outside air temperature and high outlet water temperature. In such an operating range, due to the decrease in the density of the fluid sucked into the compressor and the decrease in the flow rate accompanying the decrease in the volumetric efficiency, the amount of lubricating liquid supplied to the compression mechanism of the compressor together with the sucked fluid decreases, and wear is likely to occur in the compression mechanism.
[0005] Furthermore, if the amount of lubricating fluid stored at the bottom of the casing that is drawn into the compression mechanism along with the inhaled fluid decreases, the level of lubricating fluid stored at the bottom of the casing will rise and reach the lower end of the motor rotor, which may increase motor losses due to the agitation of the lubricating fluid. Also, if the level of lubricating fluid rises and the compression mechanism draws in the lubricating fluid stored at the bottom of the casing, liquid compression may occur in the compression mechanism, which may reduce the reliability of the compressor.
[0006] This disclosure provides a screw compressor and a refrigeration system capable of suppressing the reduction of lubricating fluid supplied to the compression mechanism. [Means for solving the problem]
[0007] A first aspect of this disclosure is a casing (14) having a compression mechanism (11) having a screw rotor (111) for compressing a refrigerant (R), a motor (13) having a rotating shaft (12) to which the screw rotor (111) is fixed, a rotor (131) fixed to the rotating shaft (12), an intake chamber (141) for drawing in refrigerant (R) from the outside, a motor chamber (142) adjacent to the intake chamber (141) for housing the motor (13), a rotor chamber (143) adjacent to the motor chamber (142) for housing the compression mechanism (11), and a discharge chamber (144) for discharging the refrigerant (R) compressed by the compression mechanism (11) to the outside, and the upstream space (US) formed by the motor chamber (142) and the intake chamber (141) upstream of the motor (13) in the flow of the refrigerant (R), The present invention provides a screw compressor (1) comprising: a first bearing (15A) provided in a casing (14) and supporting the rotating shaft (12); a sealing member (16) that partitions the upstream space (US) and the lubrication chamber (LC) surrounding the first bearing (15A); and a supply passage (17) that connects the bottom (14b) of the casing (14) where lubricating fluid (L) is stored to the lubrication chamber (LC); the rotating shaft (12) having a first flow path (121) that communicates with the lubrication chamber (LC) and extends along the axial direction (AD) of the rotating shaft (12); and a second flow path (122) that communicates with the first flow path (121) and extends in a direction intersecting the axial direction (AD) and communicates with the downstream space (DS) formed by the motor chamber (142) and the rotor chamber (143) downstream of the rotor (131) in the flow of the refrigerant (R).
[0008] According to the first point of view described above, a screw compressor (1) can be provided that can suppress the decrease in lubricating fluid (L) supplied to the compression mechanism (11).
[0009] A second aspect of this disclosure is that, in the screw compressor (1) according to the first aspect, the second flow path (122) may have a first discharge port (122a) provided on the outer circumferential surface of the rotating shaft (12) inside the coil end (132c) of the motor (13).
[0010] From the second point of view described above, the lubricating fluid (L) stored at the bottom (14b) of the casing (14) is drawn into the supply passage (17) by the pressure difference between the lubrication chamber (LC) in the upstream space (US) and the downstream space (DS), and passes sequentially through the lubrication chamber (LC), the first flow path (121), and the second flow path (122) before being discharged from the first outlet (122a). The lubricating fluid (L) discharged from the first outlet (122a) is uniformly scattered inside the coil end (132c) downstream of the rotor (131) of the motor (13) by the rotation of the rotating shaft (12), cooling the coil end (132c) and being drawn into the compression mechanism (11) by the flow of the refrigerant (R), thereby lubricating the compression mechanism (11).
[0011] A third aspect of this disclosure is the screw compressor (1) according to the first or second aspect, wherein the rotating shaft (12) has a third flow path (123) that communicates with the first flow path (121) and extends in a direction intersecting the axial direction (AD) and communicates with the motor chamber (142) upstream of the rotor (131) in the flow of the refrigerant (R), and the third flow path (123) may have a second outlet (123a) provided on the outer circumferential surface of the rotating shaft (12) inside the coil end (132c) of the motor (13).
[0012] In accordance with the third point described above, the lubricating fluid (L) stored at the bottom (14b) of the casing (14) is drawn into the supply passage (17), passes sequentially through the lubrication chamber (LC), the first flow path (121), and the third flow path (123), and is discharged from the second outlet (123a). The lubricating fluid (L) discharged from the second outlet (123a) is uniformly scattered inside the coil end (132c), which is located upstream of the rotor (131) of the motor (13) in the flow of the refrigerant (R) due to the rotation of the rotating shaft (12), cooling the coil end (132c) and being drawn into the compression mechanism (11) by the flow of the refrigerant (R), thereby lubricating the compression mechanism (11).
[0013] In a fourth aspect of this disclosure, the screw compressor (1) according to any one of the first to third aspects further comprises a second bearing (15B) provided in the casing (14) in the downstream space (DS) to support the rotating shaft (12), the rotating shaft (12) having a fourth passage (124) that communicates with the first passage (121) and extends in a direction intersecting the axial direction (AD) to communicate with the downstream space (DS), the fourth passage (124) having a third outlet (124a) for supplying the lubricating fluid (L) to the second bearing (15B).
[0014] In accordance with the fourth point of view described above, the lubricating fluid (L) stored at the bottom (14b) of the casing (14) is drawn into the supply passage (17), passes sequentially through the lubrication chamber (LC), the first flow path (121), and the fourth flow path (124), and is discharged from the third outlet (124a) to be supplied to the second bearing (15B). The lubricating fluid (L) supplied to the second bearing (15B) is used to lubricate the second bearing (15B), and then, together with the flow of the refrigerant (R), is drawn into the compression mechanism (11) to lubricate the compression mechanism (11).
[0015] In a fifth aspect of this disclosure, the screw compressor (1) according to any one of the first to fourth aspects may further include a centrifugal pump mechanism (18) that draws the lubricating fluid (L) from the lubrication chamber (LC) into the first flow path (121) by the rotation of the rotating shaft (12).
[0016] From the fifth point of view described above, in addition to the lubricating fluid (L) flowing from the lubrication chamber (LC) to the first flow path (121) due to the differential pressure between the upstream space (US) and the downstream space (DS), the centrifugal pump mechanism (18) can also pump lubricating fluid (L) from the lubrication chamber (LC) to the first flow path (121). This increases the amount of lubricating fluid (L) flowing from the bottom (14b) of the casing (14) to the lubrication chamber (LC) via the supply passage (17) and the amount of lubricating fluid (L) discharged from the second flow path (122) to the downstream space (DS). As a result, the amount of lubricating fluid (L) supplied to the compression mechanism (11) is increased, and the rise in the liquid level of the lubricating fluid (L) stored at the bottom (14b) of the casing (14) can be suppressed more effectively.
[0017] A sixth aspect of this disclosure is the screw compressor (1) according to the fifth aspect, wherein the first flow path (121) has a first opening (121a) provided on the axial (AD) end face (12e) of the rotating shaft (12) and opening to the lubrication chamber (LC), and a second opening (121b) provided on the outer circumferential surface of the rotating shaft (12) and opening to the lubrication chamber (LC), and the centrifugal pump mechanism (18) may have a closing member (18c) that closes the first opening (121a).
[0018] From the sixth point of view described above, the lubricating fluid (L) supplied to the lubrication chamber (LC) via the supply passage (17) bypasses the first opening (121a) of the end face (12e) of the rotating shaft (12), which is closed by the closing member (18c), and passes through the first bearing (15A) located on the outer circumferential surface of the end of the rotating shaft (12). This allows the lubricating fluid (L) to pass through the first bearing (15A) and lubricate the first bearing (15A) more reliably. The lubricating fluid (L) that has passed through the first bearing (15A) flows into the first flow path (121) via the second opening (121b) which opens on the outer circumferential surface of the rotating shaft (12). Furthermore, the pressure of the lubricating fluid (L) that has flowed into the first flow path (121) increases at the outer circumferential surface of the first flow path (121) due to the centrifugal force caused by the rotation of the rotating shaft (12). As a result, the differential pressure between the lubricating fluid (L) in the first channel (121) and the downstream space (DS) increases, making it possible to increase the amount of lubricating fluid (L) supplied to the downstream space (DS) via the first channel (121).
[0019] A seventh aspect of this disclosure is the screw compressor (1) according to the fifth aspect, wherein the closing member (18c) has a first intake passage (18c1) that communicates with the second opening (121b) and extends radially in the direction of the rotating shaft (12), and a second intake passage (18c2) that communicates with the first intake passage (18c1) and the first flow path (121) and extends axially (AD), wherein the inner diameter (d2) of the second intake passage (18c2) may be smaller than the inner diameter (d1) of the first flow path (121).
[0020] From the seventh point of view described above, the lubricating fluid (L) that flows into the second opening (121b) opening on the outer circumferential surface of the rotating shaft (12) passes through the first intake passage (18c1) and the second intake passage (18c2) of the closing member (18c) and flows into the first flow path (121) of the rotating shaft (12). At this time, since the inner diameter (d2) of the second intake passage (18c2) of the closing member (18c) is smaller than the inner diameter (d1) of the first flow path (121) of the rotating shaft (12), a centrifugal force acts on the lubricating fluid (L) at the outlet of the second intake passage (18c2) toward the radially outward direction (RD) of the first flow path (121) due to the rotation of the rotating shaft (12). As a result, lubricating fluid (L) is drawn from the second intake passage (18c2) of the closing member (18c) to the first flow path (121) of the rotating shaft (12), and the flow rate of lubricating fluid (L) supplied to the downstream space (DS) via the first flow path (121) increases.
[0021] An eighth aspect of this disclosure is the screw compressor (1) according to the fifth aspect, wherein the centrifugal pump mechanism (18) has an annular member (18r) positioned at the axial (AD) end of the first flow path (121), and the annular member (18r) may have a suction hole (18b) that is smaller in diameter than the first flow path (121) and communicates with the first flow path (121) and the lubrication chamber (LC).
[0022] From the eighth point of view described above, the lubricating fluid (L) that flows into the lubrication chamber (LC) from the bottom (14b) of the casing (14) via the supply passage (17) lubricates the first bearing (15A) and flows into the first flow path (121) of the rotating shaft (12) via the intake hole (18b) of the annular member (18r). At this time, since the intake hole (18b) of the annular member (18r) has a smaller diameter than the first flow path (121) of the rotating shaft (12), a centrifugal force acts on the lubricating fluid (L) at the outlet of the intake hole (18b) toward the radially outward direction (RD) of the first flow path (121) due to the rotation of the rotating shaft (12). As a result, lubricating fluid (L) is drawn from the intake hole (18b) of the annular member (18r) into the first flow path (121) of the rotating shaft (12), and lubricating fluid (L) from the lubrication chamber (LC) is drawn into the first flow path (121) via the intake hole (18b) of the annular member (18r). Therefore, the flow rate of lubricating fluid (L) supplied from the bottom (14b) of the upstream space (US) of the casing (14) to the downstream space (DS) via the supply passage (17), the lubrication chamber (LC), and the first flow path (121) increases.
[0023] A ninth aspect of the present disclosure is the screw compressor (1) according to the eighth aspect, wherein the annular member (18r) is arranged along the end face of the first bearing (15A) in the axial direction (AD) and has a plurality of through holes (18h) that communicate with a space (15s) in which the rolling elements 15r of the first bearing (15A) are housed and the lubrication chamber (LC).
[0024] According to the ninth aspect described above, the lubricating fluid (L) flowing from the bottom (14b) of the casing (14) into the lubricating chamber (LC) via the supply passage (17) passes through the through-hole (18h) of the annular member (18r) and is supplied to the space (15s) in which the rolling elements 15r of the first bearing (15A) are accommodated, lubricating the rolling elements 15r of the first bearing (15A). Further, when the lubricating fluid (L) flows from the lubricating chamber (LC) into the first flow passage (121) of the rotating shaft (12) through the suction hole (18b) of the annular member (18r), a centrifugal force acts on the lubricating fluid (L) toward the outer side in the radial direction (RD) of the first flow passage (121) due to the rotation of the rotating shaft (12), and the lubricating fluid (L) is sucked from the suction hole (18b) into the first flow passage (121). Therefore, the flow rate of the lubricating fluid (L) supplied from the bottom (14b) of the upstream space (US) of the casing (14) to the space (15s) in which the rolling elements 15r of the first bearing (15A) are accommodated and the downstream space (DS) of the casing (14) increases.
[0025] According to the tenth aspect of the present disclosure, in the screw compressor (1) according to any one of the first to ninth aspects described above, the first flow passage (121) may include a central flow passage (121c) provided at the center in the radial direction (RD) of the rotating shaft (12) and communicating with the lubricating chamber (LC), and an eccentric flow passage (121e) provided eccentrically outside the center in the radial direction (RD) and communicating with the central flow passage (121c).
[0026] According to the tenth aspect described above, a centrifugal force acts on the lubricating fluid (L) flowing from the lubricating chamber (LC) into the central flow passage (121c) of the first flow passage (121) toward the outer side in the radial direction (RD) due to the rotation of the rotating shaft (12). Due to this centrifugal force, the lubricating fluid (L) can be made to flow from the central flow passage (121c) into the eccentric flow passage (121e) provided eccentrically outside the center of the rotating shaft (12) in the radial direction (RD). Therefore, the flow rate of the lubricating fluid (L) supplied from the bottom (14b) of the upstream space (US) of the casing (14) to the downstream space (DS) via the supply passage (17), the lubricating chamber (LC), and the first flow passage (121) can be increased.
[0027] The eleventh aspect of the present disclosure is that in the screw compressor (1) according to any one of the first to tenth aspects above, the lubricating fluid (L) may be a refrigeration oil. With such a configuration, a refrigeration oil that is excellent in lubricity, stability, refrigerant solubility, low-temperature fluidity, and electrical properties, does not generate deposits at low temperatures, and has no impurities can be used as the lubricating fluid (L) of the screw compressor (1).
[0028] The twelfth aspect of the present disclosure provides a refrigeration device (10) including the screw compressor (1) according to any one of the first to eleventh aspects above. According to this aspect, it is possible to provide a refrigeration device (10) that suppresses a decrease in the lubricating fluid (L) supplied to the compression mechanism (11) of the screw compressor (1) and suppresses an increase in the liquid level of the lubricating fluid (L) stored at the bottom (14b) of the casing (14).
Brief Description of the Drawings
[0029] [Figure 1] A refrigerant circuit diagram showing an embodiment of the refrigeration device (10) and the screw compressor (1) of the present disclosure. [Figure 2] A graph showing an example of the operating range of the screw compressor (1) according to the embodiment of FIG. 1. [Figure 3] A cross-sectional view of the screw compressor (1) according to the embodiment of FIG. 1. [Figure 4] An enlarged cross-sectional view near the first bearing (15A) in the screw compressor (1) of FIG. 3. [Figure 5] An enlarged cross-sectional view corresponding to FIG. 4 showing Modification 1 of the screw compressor (1) of FIG. 3. [Figure 6] An enlarged cross-sectional view corresponding to FIG. 4 showing Modification 2 of the screw compressor (1) of FIG. 3. [Figure 7] An enlarged cross-sectional view corresponding to FIG. 4 showing Modification 3 of the screw compressor (1) of FIG. 3. [Figure 8] An enlarged cross-sectional view corresponding to FIG. 4 showing Modification 4 of the screw compressor (1) of FIG. 3. [Figure 9] An enlarged cross-sectional view corresponding to FIG. 4 showing Modification 5 of the screw compressor (1) of FIG. 3. [Figure 10] An enlarged cross-sectional view corresponding to Figure 4, showing modified example 6 of the screw compressor (1) in Figure 3. [Figure 11] An enlarged cross-sectional view corresponding to Figure 4, showing modified example 7 of the screw compressor (1) in Figure 3. [Modes for carrying out the invention]
[0030] Hereinafter, embodiments of the screw compressor (1) and refrigeration system (10) according to this disclosure will be described with reference to the drawings.
[0031] Figure 1 is a refrigerant circuit diagram showing an embodiment of the refrigeration system 10 and screw compressor 1 according to the present disclosure. The refrigeration system 10 of this embodiment includes a screw compressor 1. Specifically, the refrigeration system 10 is, for example, a water heater or a chiller unit. Alternatively, the refrigeration system 10 may be, for example, an air conditioning system.
[0032] The refrigeration system 10 has a refrigerant circuit 2 filled with refrigerant R and performs a vapor compression type refrigeration cycle. The refrigerant circuit 2 includes, for example, a screw compressor 1, a heat sink 3, a first expansion valve 4, a gas-liquid separator 5, a second expansion valve 6, an evaporator 7, an injection mechanism 8, and a controller 9. In Figure 1, solid arrows indicate the flow of refrigerant R in the refrigerant circuit 2, and dotted lines indicate the electrical connections between the controller 9 and each component.
[0033] The screw compressor 1 is equipped with a generally cylindrical casing 14 having an inlet 14a and a discharge port 14e. As will be described in detail later, the screw compressor 1 compresses the refrigerant R in a low-pressure gas state drawn in from the inlet 14a and discharges the refrigerant R in a high-pressure gas state from the discharge port 14e.
[0034] The refrigerant R, in the state of a high-pressure gas discharged from the discharge port 14e of the screw compressor 1, releases heat and condenses in the radiator 3. The refrigerant R, which has condensed in the radiator 3 into a high-pressure liquid refrigerant, is depressurized in the first expansion valve 4, and the gas and liquid are separated in the gas-liquid separator 5 and stored at the bottom. The refrigerant R in the state of a liquid refrigerant stored at the bottom of the gas-liquid separator 5 flows out from the refrigerant outlet 51 of the gas-liquid separator 5, is depressurized in the second expansion valve 6, and evaporates in the evaporator 7, absorbing heat. The refrigerant R evaporated in the evaporator 7 is drawn into the suction port 14a of the screw compressor 1 in the state of a low-pressure gas.
[0035] The injection mechanism 8 includes, for example, an injection pipe 81, a solenoid valve 82, a branch pipe 83, and a flow control valve 84. The injection pipe 81 has, for example, one end connected to an injection port 52 located at the bottom of the gas-liquid separator 5, and the other end connected to the casing 14 of the screw compressor 1. The solenoid valve 82 is located in the middle of the injection pipe 81 and is opened and closed under the control of a controller 9. The branch pipe 83 branches off from the injection pipe 81 between the solenoid valve 82 and the screw compressor 1 and is connected to the refrigerant circuit 2 between the evaporator 7 and the screw compressor 1. The flow control valve 84 is located in the middle of the branch pipe 83 and its opening degree is adjusted under the control of a controller 9.
[0036] The controller 9, for example, opens the solenoid valve 82 to supply liquid refrigerant R to the screw compressor 1 when the temperature of the refrigerant R discharged from the screw compressor 1 exceeds a predetermined threshold. The controller 9 also adjusts the opening degree of the flow control valve 84 according to the temperature of the refrigerant R discharged from the screw compressor 1. In this way, the controller 9 adjusts the amount of refrigerant R supplied to the screw compressor 1 by the injection mechanism 8 and controls the temperature of the refrigerant R discharged from the screw compressor 1.
[0037] Figure 2 is a graph showing an example of the operating range of the screw compressor 1 according to this embodiment. In the graph of Figure 2, the horizontal axis is the saturation suction temperature (SST), and the vertical axis is the saturation discharge temperature (SDT). In Figure 2, the dashed line shows the operating range of a conventional screw compressor using R134a as the refrigerant, and the solid line shows the operating range of the screw compressor 1 of this embodiment, which uses, for example, R454C as the refrigerant R. In addition to R454C, the screw compressor 1 of this embodiment can be used to compress refrigerants such as R134a, R32, R1234ze, R1234yf, ammonia, and propane.
[0038] In response to the growing demand for replacing gas boilers with heat pump chillers due to international decarbonization efforts and the uncertain energy situation, there is a need to improve the performance of refrigeration equipment 10 that can also be used as a heat pump chiller. Specifically, there is a need to expand the operating range of the screw compressor 1 installed in the refrigeration equipment 10 to a range with lower SST and higher SDT than conventional screw compressors, as shown by the arrows in Figure 2, i.e., to a region of low ambient temperature and high outlet water temperature. Here, the region of low ambient temperature and high outlet water temperature includes, for example, a region where the compression ratio is 7 or higher, a region where SST is less than 25°C, a region where STD exceeds 68°C, or a region where STD exceeds 75°C.
[0039] Figure 3 is a cross-sectional view of the screw compressor 1 of this embodiment, which is mounted on the refrigeration device 10 shown in Figure 1. As described above, the screw compressor 1 is equipped with a generally cylindrical casing 14 having an inlet 14a and a discharge port 14e, and compresses the refrigerant R in a low-pressure gas state drawn in from the inlet 14a and discharges the refrigerant R in a high-pressure gas state from the discharge port 14e.
[0040] The screw compressor 1 comprises a compression mechanism 11, a rotating shaft 12, a motor 13, a casing 14, a first bearing 15A, a sealing member 16, and a supply passage 17. In the example shown in Figure 3, the screw compressor 1 further comprises a second bearing 15B and a third bearing 15C. The screw compressor 1 may also further comprise an inverter unit 19.
[0041] The screw compressor 1 of this embodiment is characterized by having a configuration that solves the following problems. In the operating range of the screw compressor 1 shown by the solid line in Figure 2, in the operating range with a lower SST and higher SDT than the operating range of a conventional screw compressor shown by the dashed line, the density of the inhaled refrigerant R decreases, and the flow rate of the refrigerant R decreases along with the decrease in volumetric efficiency. As a result, the amount of lubricating fluid L that reaches the compression mechanism 11 along with the refrigerant R decreases. The lubricating fluid L is, for example, refrigerant oil.
[0042] Furthermore, as the amount of lubricating fluid L reaching the compression mechanism 11 along with the refrigerant R decreases, the liquid level of the lubricating fluid L stored at the bottom 14b of the casing 14 rises and reaches the lower end of the rotor 131 of the motor 13, increasing the losses caused by the rotor 131 agitating the lubricating fluid L. Also, if the liquid level of the lubricating fluid L stored at the bottom 14b of the casing 14 rises and the lubricating fluid L is drawn into the compression mechanism 11, liquid compression may occur in the compression mechanism 11, potentially reducing the reliability of the screw compressor 1.
[0043] The following describes in detail the configuration of each part of the screw compressor 1 that solves the aforementioned problems.
[0044] As shown in Figure 3, the casing 14 has an intake chamber 141, a motor chamber 142, a rotor chamber 143, and a discharge chamber 144. In the example shown in Figure 3, the casing 14 is configured to be separable into three parts: a first part 14A that forms the intake chamber 141, a second part 14B that forms the motor chamber 142 and the rotor chamber 143, and a third part 14C that forms the discharge chamber 144. In other words, the screw compressor 1 has a semi-enclosed configuration.
[0045] The intake chamber 141 draws in refrigerant R from the outside. Specifically, the first part 14A of the casing 14 that forms the intake chamber 141 is provided with an intake port 14a for drawing in refrigerant R in the form of a low-pressure gas supplied from the evaporator 7. For example, a bottomed cylindrical filter 14f is attached to the intake port 14a. When the refrigerant R is compressed by the compression mechanism 11, the intake chamber 141 draws in refrigerant R in the form of a low-pressure gas supplied from the evaporator 7 outside the screw compressor 1 through the intake port 14a and the filter 14f. The first part 14A of the casing 14 also has a plurality of ribs 14r1 that extend radially in the radial direction of the rotation axis 12, with the rotation axis 12 as the center. The radial ribs 14r1 support the first bearing 15A at their center.
[0046] The motor chamber 142 houses the motor 13 adjacent to the intake chamber 141. The motor 13 has a rotor 131 fixed to the rotating shaft 12. The motor 13 also has a stator 132 arranged around the rotor 131. Permanent magnets are embedded in the rotor 131, and coils are wound around the stator 132. Coil ends 132c are formed at both ends of the stator 132 in the axial direction AD of the rotating shaft 12 by coils protruding from both ends of the stator 132.
[0047] The motor chamber 142 has, for example, a cylindrical inner wall having a predetermined distance from the outer surface of the stator 132, and a plurality of protrusions that project inward from the inner wall in the radial direction RD of the rotating shaft 12 to support the stator 132. The plurality of protrusions of the motor chamber 142 that support the stator 132 are provided at equal intervals in the circumferential direction of the inner wall of the motor chamber 142 and extend along the axial direction AD of the rotating shaft 12.
[0048] In the example shown in Figure 3, an inverter unit 19 is provided on the second portion 14B of the casing 14 that forms the motor chamber 142. The inverter unit 19 includes, for example, an inverter 191 that supplies power to the motor 13, a cooling unit 192 that cools the inverter 191, and a cover 193 that covers them. Note that in Figure 3, the inverter 191 and cover 193 are not shown, and their approximate shapes are indicated by dashed lines.
[0049] The inverter 191 is connected to the motor 13, for example, via a terminal portion 191a, and supplies power to the motor 13. The cooling portion 192 is, for example, a metal plate-shaped member with excellent thermal conductivity, and has a flow path for passing the refrigerant R in liquid form, which is supplied from the injection mechanism 8 shown in Figure 1 to the casing 14 of the screw compressor 1. The cover 193 is, for example, a resin member that covers the inverter 191 and the cooling portion 192, and is attached to the outside of the second portion 14B of the casing 14.
[0050] The rotor chamber 143 houses the compression mechanism 11 adjacent to the motor chamber 142. The compression mechanism 11 has a screw rotor 111 and compresses the refrigerant R. More specifically, the compression mechanism 11 has a screw rotor 111 fixed to the rotating shaft 12 and a gate rotor 112 that engages with a helical groove provided in the screw rotor 111 and rotates around an axis perpendicular to the rotating shaft 12.
[0051] The compression mechanism 11 compresses the refrigerant R by drawing it into a compression chamber formed by the helical grooves of the screw rotor 111, the gate rotor 112, and the cylindrical inner wall surface provided in the second portion 14B of the casing 14, as the screw rotor 111 rotates. Once the compression of the refrigerant R is complete, the compression chamber is connected to the discharge chamber 144 via passages provided in the second portion 14B and the third portion 14C of the casing 14.
[0052] The discharge chamber 144 discharges the refrigerant R compressed by the compression mechanism 11 to the outside. More specifically, the third portion 14C of the casing 14 that forms the discharge chamber 144 is provided with a discharge port 14e for discharging the refrigerant R in the state of high-pressure gas compressed by the compression mechanism 11. The discharge port 14e opens, for example, at the upper end of a cylindrical portion 14p attached to the opening at the upper end of the third portion 14C.
[0053] The cylindrical portion 14p has, for example, a cylindrical main body portion having openings at its upper and lower ends, and an annular flange portion projecting radially outward from the outer circumferential surface of the upper end of the main body portion. The cylindrical portion 14p is inserted into the discharge chamber 144 through the opening at the upper end of the discharge chamber 144 and attached to the upper end of the third portion 14C of the casing 14 via the flange portion. The discharge chamber 144 has a cylindrical inner circumferential wall coaxial with the cylindrical portion 14p. As a result, a cylindrical space is formed between the main body portion of the cylindrical portion 14p and the inner circumferential wall of the discharge chamber 144.
[0054] Furthermore, the second portion 14B of the casing 14 has multiple radially arranged ribs 14r2 between the motor chamber 142 and the rotor chamber 143, similar to the multiple ribs 14r1 provided on the first portion 14A of the casing 14. The radially arranged multiple ribs 14r2 support the second bearing 15B at their center. The second portion 14B of the casing 14 also supports the third bearing 15C via a support member 14s. The support member 14s is supported by a cylindrical inner wall provided on the second portion 14B of the casing 14, which together with the compression mechanism 11 forms a compression chamber, and is positioned adjacent to the partition wall of the third portion 14C of the casing 14.
[0055] As described above, the first bearing 15A is supported in the center of the radial ribs 14r1 provided on the first portion 14A of the casing 14. The first bearing 15A is provided in the casing 14 in the upstream space US formed by the motor chamber 142 and the intake chamber 141, upstream of the motor 13 in the flow of the refrigerant R, and rotatably supports the rotating shaft 12. In the example shown in Figure 3, the upstream space US of the casing 14 is the space further upstream of the coil end 132c of the motor 13, which is located upstream in the flow direction of the refrigerant R flowing from the intake chamber 141 to the rotor chamber 143 along the axial direction AD of the rotating shaft 12.
[0056] As described above, the second bearing 15B is supported in the center of the radial ribs 14r2 provided on the second portion 14B of the casing 14, and rotatably supports the rotating shaft 12 in the downstream space DS located downstream of the rotor 131 of the motor 13 in the flow of the refrigerant R. As described above, the third bearing 15C is supported on the second portion 14B of the casing 14 via a support member 14s, and rotatably supports the downstream end of the rotating shaft 12 in the flow direction of the refrigerant R.
[0057] Figure 4 is an enlarged cross-sectional view of the vicinity of the first bearing 15A in the screw compressor 1 of Figure 3. In the example shown in Figure 4, a plurality of ribs 14r1 arranged radially around the rotation axis 12 have an opening 14o in the center that supports the bearing holder 14c. The bearing holder 14c is coaxial with the rotation axis 12 and has a short-axis cylindrical shape in which the axial AD dimension is smaller than the radial RD dimension. The bearing holder 14c also has a bottomed cylindrical shape with an opening at one end in the axial AD and the other end closed.
[0058] The opening of the bearing holder 14c communicates with the opening 14o provided in the center of the radial rib 14r1. The inner diameter of the bearing holder 14c is smaller on the bottom wall side than on the opening side, and a stepped portion in the radial direction RD is formed in the middle of the axial direction AD. The first bearing 15A is fitted inside the opening of the bearing holder 14c and is fixed to the bearing holder 14c by being supported by the portion of the inner wall of the bearing holder 14c on the opening side and the stepped portion. A space is formed between the first bearing 15A and the bottom wall of the bearing holder 14c.
[0059] The sealing member 16 is provided to partition the upstream space US of the casing 14 from the lubrication chamber LC. In the example shown in Figure 4, the lubrication chamber LC is defined, for example, by the bearing holder 14c, the inner circumferential wall of the opening 14o of the rib 14r1, and the sealing member 16, and houses the first bearing 15A. The sealing member 16 has an annular shape through which the rotating shaft 12 is inserted, and is fitted between the inner circumferential wall of the opening 14o provided in the center of the radial rib 14r1 and the outer circumferential surface of the rotating shaft 12. Any sealing member can be used as the sealing member 16, such as a labyrinth seal, oil seal, or mechanical seal.
[0060] As shown in Figures 3 and 4, the supply passage 17 connects the bottom 14b of the casing 14, where the lubricating fluid L is stored, to the lubrication chamber LC in the upstream space US. As shown in Figure 4, the supply passage 17 includes, for example, a first supply passage 171 provided in the rib 14r1 of the casing 14 and a second supply passage 172 provided in the bearing holder 14c. The supply passage 17 extends, for example, from the lubrication chamber LC along the radial direction RD of the rotating shaft 12 toward the bottom 14b of the casing 14. Furthermore, as shown in Figure 3, the supply passage 17 extends along the axial direction AD of the rotating shaft 12 at the bottom 14b of the casing 14 and communicates with the intake chamber 141 and motor chamber 142, which form the upstream space US.
[0061] As described above, the rotating shaft 12 is fixed to the screw rotor 111 of the compression mechanism 11. The rotating shaft 12 is also fixed to the rotor 131 of the motor 13. Furthermore, the rotating shaft 12 is rotatably supported by the casing 14 via the first bearing 15A, the second bearing 15B, and the third bearing 15C. As a result, the rotating shaft 12 rotates together with the rotor 131 of the motor 13, causing the screw rotor 111 to rotate.
[0062] As shown in Figure 3, the rotating shaft 12 has a first flow path 121 and a second flow path 122. As shown in Figure 4, the first flow path 121 communicates with the lubrication chamber LC and extends along the axial direction AD of the rotating shaft 12. As shown in Figure 3, the second flow path 122 communicates with the first flow path 121 and extends in a direction intersecting the axial direction AD to communicate with the downstream space DS. The downstream space DS is a space formed by the motor chamber 142 and the rotor chamber 143 downstream of the rotor 131 of the motor 13 from the flow of the refrigerant R.
[0063] More specifically, the downstream space DS is the space downstream of the rotor 131 of the motor 13 in the flow direction along the axial direction AD of the rotation axis 12 of the refrigerant R that is drawn in from the intake chamber 141, sequentially through the motor chamber 142 and rotor chamber 143 to the compression chamber formed by the compression mechanism 11. Furthermore, the downstream space DS is the space upstream in the flow direction of the refrigerant R from the compression chamber formed between the screw rotor 111 and gate rotor 112 of the compression mechanism 11 and the inner circumferential wall of the second portion 14B of the casing 14.
[0064] In the example shown in Figure 3, the second flow path 122 of the rotating shaft 12 has a first discharge port 122a provided on the outer circumferential surface of the rotating shaft 12, inside the coil end 132c of the motor 13 located downstream in the flow direction of the refrigerant R.
[0065] Furthermore, as shown in Figure 3, the rotating shaft 12 may have a third flow path 123. The third flow path 123 communicates with the first flow path 121 and extends in a direction intersecting the axial direction AD of the rotating shaft 12, communicating with the motor chamber 142 upstream of the rotor 131 of the motor 13 in the flow of the refrigerant R. The third flow path 123 has a second outlet 123a provided on the outer circumferential surface of the rotating shaft 12 inside the coil end 132c of the motor 13.
[0066] Furthermore, the screw compressor 1 of this embodiment is provided with a second bearing 15B in the downstream space DS, which is located in the casing 14 as described above and supports the rotating shaft 12. In this case, the rotating shaft 12 may have a fourth flow path 124 that communicates with the first flow path 121 and extends in a direction intersecting the axial direction AD of the rotating shaft 12 and communicates with the downstream space DS. The fourth flow path 124 has, for example, a third outlet 124a that opens into the inner circumferential wall of a cylindrical opening provided in the central part of the radial rib 14r2 and supporting the second bearing 15B, and supplies lubricating fluid L to the second bearing 15B.
[0067] Furthermore, the rotating shaft 12 may have, for example, a plurality of second flow paths 122. In the example shown in Figure 3, the rotating shaft 12 has second flow paths 122 inside the coil end 132c of the motor 13 located downstream in the flow direction of the refrigerant R, and downstream of the coil end 132c in the flow direction of the refrigerant R. The second flow path 122 located downstream of the motor 13 in the flow direction of the refrigerant R has a fourth discharge port 122b provided on the outer circumferential surface of the rotating shaft 12 upstream of the screw rotor 111 of the compression mechanism 11 in the flow direction of the refrigerant R, and communicating with the rotor chamber 143.
[0068] The operation of the screw compressor 1 and refrigeration system 10 of this embodiment will be described below.
[0069] For example, when the inverter unit 19 of the screw compressor 1 is controlled by the controller 9 shown in Figure 1 and power is supplied to the motor 13, the rotor 131 of the motor 13 rotates, causing the screw rotor 111 to rotate the rotating shaft 12 to which it is fixed. As a result, the compression mechanism 11 draws the refrigerant R into the compression chamber formed between the screw rotor 111 and the gate rotor 112 and the inner circumferential wall of the second portion 14B of the casing 14 and compresses it.
[0070] The refrigerant R, in the state of a high-pressure gas compressed by the compression mechanism 11, is discharged from the compression chamber to the discharge chamber 144 via passages provided in the second part 14B and the third part 14C of the casing 14. It then swirls between the cylindrical part 14p and the inner circumferential wall of the discharge chamber 144 and is discharged to the outside from the discharge port 14e. As a result, the lubricating liquid L contained in the refrigerant R is separated by centrifugal force. The lubricating liquid L separated from the refrigerant R flows down from the inner circumferential wall of the discharge chamber 144 to the bottom, communicates with the bottom of the discharge chamber 144, and flows into the lubricating liquid storage chamber 14d located below the rotor chamber 143. The lubricating liquid L is then stored in the lubricating liquid storage chamber 14d and recovered.
[0071] Furthermore, as the compression mechanism 11 draws refrigerant R into the compression chamber, the intake chamber 141 of the casing 14 draws in the refrigerant R in the form of a low-pressure gas supplied from the evaporator 7 outside the screw compressor 1 via the discharge port 14e and the filter 14f. The refrigerant R drawn into the intake chamber 141 flows from the intake chamber 141 into the motor chamber 142, cools the motor 13 by passing through the space between the inner circumferential wall of the motor chamber 142 and the stator 132, and between the rotor 131 and the stator 132, and then flows into the rotor chamber 143 by passing through the radial ribs 14r2. The refrigerant R that flows into the rotor chamber 143 is drawn into the compression chamber formed by the compression mechanism 11 and the casing 14 and compressed.
[0072] The operating range of the screw compressor 1 in this embodiment is required to be expanded to the range shown by the solid line, which includes a low SST and high SDT region, compared to the operating range of a conventional screw compressor shown by the dashed line in Figure 2, as described above. In such an operating range, as described above, the challenge is to suppress the decrease in lubricating fluid L that reaches the compression mechanism 11 together with the refrigerant R. As a means to solve this problem, the screw compressor 1 in this embodiment has the following configuration.
[0073] The screw compressor 1 comprises a compression mechanism 11 having a screw rotor 111 for compressing refrigerant R, a rotating shaft 12 to which the screw rotor 111 is fixed, and a motor 13 having a rotor 131 fixed to the rotating shaft 12. The screw compressor 1 also comprises a casing 14, a first bearing 15A, a sealing member 16, and a supply passage 17. The casing 14 has an intake chamber 141 for drawing in refrigerant R from the outside, a motor chamber 142 adjacent to the intake chamber 141 for housing the motor 13, a rotor chamber 143 adjacent to the motor chamber 142 for housing the compression mechanism 11, and a discharge chamber 144 for discharging the refrigerant R compressed by the compression mechanism 11 to the outside. The first bearing 15A is provided in the casing 14 in the upstream space US formed by the motor chamber 142 and the intake chamber 141, upstream of the motor 13 in the flow of refrigerant R, and supports the rotating shaft 12. The sealing member 16 separates the upstream space US from the lubrication chamber LC surrounding the first bearing 15A. The supply passage 17 connects the bottom 14b of the casing 14, where the lubricating fluid L is stored, to the lubrication chamber LC. The rotating shaft 12 also has a first passage 121 and a second passage 122. The first passage 121 communicates with the lubrication chamber LC and extends along the axial direction AD of the rotating shaft 12. The second passage 122 communicates with the first passage 121 and extends in a direction intersecting the axial direction AD, communicating with the downstream space DS formed by the motor chamber 142 and rotor chamber 143 downstream of the rotor 131 in the flow of the refrigerant R.
[0074] In this configuration, as the refrigerant R flows from the upstream space US upstream of the motor 13 to the downstream space DS downstream of the rotor 131, a pressure loss occurs as it passes through the motor chamber 142 housing the motor 13. Therefore, the pressure of the refrigerant R in the downstream space DS is lower than the pressure of the refrigerant R in the upstream space US. In this state, the supply passage 17 connects the bottom 14b of the casing 14 and the lubrication chamber LC in the upstream space US, and the first passage 121 and the second passage 122 of the rotating shaft 12 connect the lubrication chamber LC and the downstream space DS.
[0075] As a result, the differential pressure between the upstream space US and the downstream space DS causes the lubricating fluid L stored at the bottom 14b of the casing 14 to be drawn into the supply passage 17 and flow into the lubrication chamber LC, lubricating the first bearing 15A. Furthermore, the lubricating fluid L that has lubricated the first bearing 15A in the lubrication chamber LC flows from the lubrication chamber LC into the first flow path 121 of the rotating shaft 12 due to the differential pressure between the lubrication chamber LC and the downstream space DS, and is discharged from the first flow path 121 through the second flow path 122 to the downstream space DS.
[0076] The lubricating fluid L discharged from the second flow path 122 of the rotating shaft 12 into the downstream space DS is uniformly scattered around the rotating shaft 12 in the downstream space DS, which is downstream of the rotor 131 of the motor 13 in the flow direction of the refrigerant R, due to the rotation of the rotating shaft 12 and centrifugal force. As a result, the lubricating fluid L reaches the compression mechanism 11 together with the refrigerant R and lubricates the compression mechanism 11. Therefore, with the screw compressor 1 of this embodiment, the decrease in the lubricating fluid L supplied to the compression mechanism 11 can be suppressed. This makes it possible to suppress wear on the compression mechanism 11 in the expanded operating range of the screw compressor 1, as shown by the solid line in Figure 2.
[0077] Furthermore, by supplying lubricating fluid L to the compression mechanism 11 from the bottom 14b of the casing 14 via the supply passage 17, the lubrication chamber LC, and the first and second passages 121 and 122 of the rotating shaft 12, the rise in the liquid level of the lubricating fluid L stored at the bottom 14b of the casing 14 is suppressed. This suppresses losses and vibrations caused by the rotor 131 of the motor 13 agitating the lubricating fluid L. In addition, it prevents the compression mechanism 11 from sucking in the lubricating fluid L stored at the bottom 14b of the casing 14, thereby suppressing liquid compression and improving the reliability of the screw compressor 1.
[0078] Furthermore, by passing the lubricating fluid L through the first flow path 121 and the second flow path 122 of the rotating shaft 12, the rotating shaft 12 is cooled by the lubricating fluid L, and the rotor 131 of the motor 13 can be cooled via the rotating shaft 12. Therefore, the operating range of the screw compressor 1, which is limited by the temperature of the motor 13, can be expanded. In addition, by reducing the amount of lubricating fluid L passing between the rotor 131 and the stator 132, the occurrence of losses due to the agitation of the lubricating fluid L between the rotor 131 and the stator 132 can be suppressed.
[0079] Furthermore, the supply passage 17 and the first and second flow paths 121 and 122 of the rotating shaft 12 communicate with the low-pressure upstream space US and downstream space DS, which are located upstream of the compression chamber formed between the compression mechanism 11 and the casing 14, via the lubrication chamber LC. In other words, the supply passage 17, the lubrication chamber LC, and the first and second flow paths 121 and 122 of the rotating shaft 12 do not communicate with the low-pressure space located upstream of the compression chamber and the high-pressure space located downstream of the compression chamber. This reduces the temperature and pressure loss of the refrigerant R in the screw compressor 1.
[0080] Furthermore, in the screw compressor 1 of this embodiment, the second flow path 122 of the rotating shaft 12 has a first discharge port 122a provided on the outer circumferential surface of the rotating shaft 12 inside the coil end 132c of the motor 13.
[0081] With this configuration, the lubricating liquid L discharged from the first outlet 122a of the second flow path 122 is uniformly scattered around the rotating shaft 12 by the rotation of the rotating shaft 12 and centrifugal force, and is sprayed onto the inside of the coil end 132c. As a result, even if the temperature rises as the refrigerant R cools the motor 13 as it passes through the motor chamber 142, and the temperature difference between the refrigerant R and the coil end 132c decreases, reducing the cooling effect of the refrigerant R on the coil end 132c, the coil end 132c can still be cooled by the lubricating liquid L. This expands the operating range of the screw compressor 1, which is constrained by the temperature of the motor 13.
[0082] Furthermore, in the screw compressor 1 of this embodiment, the rotating shaft 12 has a third flow path 123 that communicates with the first flow path 121 and extends in a direction intersecting the axial direction AD, and communicates with the motor chamber 142 upstream of the rotor 131 in the flow of the refrigerant R. The third flow path 123 has a second discharge port 123a provided on the outer circumferential surface of the rotating shaft 12 inside the coil end 132c of the motor 13.
[0083] With this configuration, the lubricating fluid L discharged from the second outlet 123a of the third flow path 123 is uniformly scattered around the rotating shaft 12 by the rotation of the rotating shaft 12 and centrifugal force, and is sprayed onto the inside of the coil end 132c, which is located upstream of the rotor 131 in the flow of the refrigerant R. As a result, the coil end 132c can be cooled by the lubricating fluid L in addition to the cooling by the refrigerant R. This expands the operating range of the screw compressor 1, which is limited by the temperature of the motor 13.
[0084] Furthermore, the screw compressor 1 of this embodiment is further provided with a second bearing 15B in the downstream space DS, which is provided in the casing 14 and supports the rotating shaft 12. The rotating shaft 12 has a fourth passage 124 that communicates with the first passage 121 and extends in a direction intersecting the axial direction AD, and communicates with the downstream space DS. The fourth passage 124 has a third outlet 124a that supplies lubricating fluid L to the second bearing 15B.
[0085] With this configuration, the lubricating fluid L stored at the bottom 14b of the casing 14 can be supplied to the fourth flow path 124 via the supply passage 17, the lubrication chamber LC, and the first flow path 121, and then supplied to the first bearing 15A from the third outlet 124a of the fourth flow path 124. This ensures more reliable lubrication of the second bearing 15B, which is located in the downstream space DS downstream of the rotor 131 of the motor 13, thereby improving the reliability of the second bearing 15B.
[0086] Furthermore, in the screw compressor 1 of this embodiment, the lubricating fluid L is refrigerant oil. With this configuration, refrigerant oil, which has excellent lubricity, stability, refrigerant solubility, low-temperature fluidity, and electrical properties, does not produce precipitates at low temperatures, and is free of impurities, can be used as the lubricating fluid L of the screw compressor 1.
[0087] Furthermore, the refrigeration system 10 of this embodiment is equipped with the aforementioned screw compressor 1. With this configuration, the refrigeration system 10 can suppress the decrease in lubricating fluid L supplied to the compression mechanism 11 of the screw compressor 1, and can also suppress the rise in the liquid level of the lubricating fluid L stored at the bottom 14b of the casing 14.
[0088] As described above, this embodiment provides a screw compressor 1 and a refrigeration device 10 that can suppress the decrease in lubricating fluid L supplied to the compression mechanism 11.
[0089] It should be noted that the screw compressor 1 and refrigeration system 10 according to this disclosure are not limited to the configuration of the embodiments described above. Hereinafter, a modified example of the screw compressor 1 according to the embodiments described above will be described with reference to Figures 5 to 10.
[0090] Figure 5 is an enlarged cross-sectional view corresponding to Figure 4, showing a modified example 1 of the screw compressor 1 of Figure 3. In this modified example, the screw compressor 1 is further equipped with a centrifugal pump mechanism 18 that draws lubricating fluid L from the lubrication chamber LC into the first flow path 121 of the rotating shaft 12 by the rotation of the rotating shaft 12.
[0091] With this configuration, in addition to the lubricating fluid L flowing from the lubricating chamber LC to the first flow path 121 due to the differential pressure between the lubricating chamber LC and the downstream space DS, the centrifugal pump mechanism 18 can also pump lubricating fluid L from the lubricating chamber LC to the first flow path 121. As a result, the amount of lubricating fluid L flowing from the bottom 14b of the casing 14 to the lubricating chamber LC via the supply passage 17 and the amount of lubricating fluid L released from the second flow path 122 to the downstream space DS increases. Consequently, the amount of lubricating fluid L supplied to the compression mechanism 11 increases, and the rise in the liquid level of the lubricating fluid L stored at the bottom 14b of the casing 14 can be suppressed more effectively.
[0092] More specifically, in the modified screw compressor 1, the first flow path 121 of the rotating shaft 12 has a first opening 121a provided on the axial end face AD of the rotating shaft 12 and opening into the lubrication chamber LC, and a second opening 121b provided on the outer circumferential surface of the rotating shaft 12 and opening into the lubrication chamber LC. The centrifugal pump mechanism 18 also has a closing member 18c that closes the first opening 121a of the first flow path 121.
[0093] With this configuration, the lubricating fluid L supplied to the lubrication chamber LC via the supply passage 17 bypasses the first opening 121a of the end face 12e of the rotating shaft 12, which is closed by the closing member 18c, and passes through the first bearing 15A located on the outer circumferential surface of the end of the rotating shaft 12. This allows the lubricating fluid L to pass through the first bearing 15A, ensuring more reliable lubrication of the rolling elements 15r of the first bearing 15A. The lubricating fluid L that has passed through the first bearing 15A flows into the first passage 121 via the second opening 121b that opens on the outer circumferential surface of the rotating shaft 12. The lubricating fluid L that has flowed into the first passage 121 is subjected to centrifugal force due to the rotation of the rotating shaft 12, causing the pressure to rise on the outer circumferential surface of the first passage 121. As a result, the differential pressure between the lubricating fluid L in the first passage 121 and the downstream space DS increases, allowing for an increase in the amount of lubricating fluid L supplied from the first passage 121 to the downstream space DS via the second passage 122, third passage 123, or fourth passage 124.
[0094] Figure 6 is an enlarged cross-sectional view corresponding to Figure 4, showing a modified example 2 of the screw compressor 1 of Figure 3. In this modified screw compressor 1, the closing member 18c of the centrifugal pump mechanism 18 has a first suction passage 18c1 that communicates with the second opening 121b and extends radially RD of the rotating shaft 12, and a second suction passage 18c2 that communicates with the first suction passage 18c1 and the first flow path 121 and extends axially AD. The inner diameter d2 of the second suction passage 18c2 of the closing member 18c is smaller than the inner diameter d1 of the first flow path 121 of the rotating shaft 12.
[0095] With this configuration, the lubricating fluid L that flows into the second opening 121b opening on the outer circumferential surface of the rotating shaft 12 passes through the first intake passage 18c1 and the second intake passage 18c2 of the closing member 18c and flows into the first flow path 121 of the rotating shaft 12. Here, since the inner diameter d2 of the second intake passage 18c2 of the closing member 18c is smaller than the inner diameter d1 of the first flow path 121 of the rotating shaft 12, a centrifugal force acts on the lubricating fluid L at the outlet of the second intake passage 18c2 toward the outside in the radial direction RD of the first flow path 121 due to the rotation of the rotating shaft 12.
[0096] As a result, lubricating fluid L is drawn from the second intake passage 18c2 of the closing member 18c to the first flow path 121 of the rotating shaft 12, increasing the flow rate of lubricating fluid L supplied to the downstream space DS via the first flow path 121. Furthermore, by pressurizing the lubricating fluid L from the second intake passage 18c2 to the first flow path 121 by the centrifugal pump mechanism 18, the lubricating fluid L is more reliably passed through to the first bearing 15A in the lubrication chamber LC, and the rolling elements 15r of the first bearing 15A are more reliably lubricated.
[0097] Figure 7 is an enlarged cross-sectional view corresponding to Figure 4, showing a modified example 3 of the screw compressor 1 of Figure 3. In this modified screw compressor 1, the centrifugal pump mechanism 18 has an annular member 18r positioned at the axial AD end of the first flow path 121, instead of the closing member 18c shown in Figures 5 and 6. The annular member 18r has a suction hole 18b that is smaller in diameter than the first flow path 121 and communicates with the first flow path 121 and the lubrication chamber LC.
[0098] With this configuration, the lubricating fluid L that flows from the bottom 14b of the casing 14 into the lubrication chamber LC via the supply passage 17 lubricates the rolling elements 15r of the first bearing 15A and flows into the first flow path 121 of the rotating shaft 12 via the intake hole 18b of the annular member 18r. At this time, since the intake hole 18b of the annular member 18r has a smaller diameter than the first flow path 121 of the rotating shaft 12, a centrifugal force acts on the lubricating fluid L at the outlet of the intake hole 18b toward the outside of the radial direction RD of the first flow path 121 due to the rotation of the rotating shaft 12.
[0099] As a result, lubricating fluid L is drawn from the intake hole 18b of the annular member 18r into the first flow path 121 of the rotating shaft 12, and lubricating fluid L from the lubrication chamber LC is drawn into the first flow path 121 via the intake hole 18b of the annular member 18r. Therefore, the flow rate of lubricating fluid L supplied from the bottom 14b of the upstream space US of the casing 14 to the downstream space DS via the supply passage 17, the lubrication chamber LC, and the first flow path 121 increases.
[0100] Figure 8 is an enlarged cross-sectional view corresponding to Figure 4, showing a modified example 4 of the screw compressor 1 of Figure 3. In this modified screw compressor 1, the annular member 18r is arranged along the end face of the first bearing 15A in the axial direction AD of the rotating shaft 12 and has a plurality of through holes 18h that communicate with the space 15s in which the rolling elements 15r of the first bearing 15A are housed and the lubrication chamber LC.
[0101] With this configuration, the screw compressor 1 of this modified example can achieve the same effects as the screw compressor 1 of modified example 3 shown in Figure 7. Specifically, the lubricating fluid L that flows into the lubrication chamber LC from the bottom 14b of the casing 14 via the supply passage 17 passes through the through hole 18h of the annular member 18r and is supplied to the space 15s in which the rolling elements 15r of the first bearing 15A are housed, thereby lubricating the first bearing 15A.
[0102] Furthermore, when the lubricating fluid L flows from the lubrication chamber LC into the first flow path 121 of the rotating shaft 12 via the intake hole 18b of the annular member 18r, centrifugal force acts outward in the radial direction RD of the first flow path 121, drawing the fluid into the first flow path 121 from the intake hole 18b. Consequently, the flow rate of the lubricating fluid L supplied from the bottom 14b of the upstream space US of the casing 14 to the space 15s where the rolling elements 15r of the first bearing 15A are housed and to the downstream space DS increases.
[0103] Figures 9, 10, and 11 are enlarged cross-sectional views corresponding to Figure 4, showing modified versions 5, 6, and 7 of the screw compressor 1 in Figure 3, respectively. The screw compressors 1 of modified versions 5, 6, and 7 differ from the screw compressors 1 of modified versions 2, 3, and 4 shown in Figures 6, 7, and 8, in that the first flow path 121 of the rotating shaft 12 has a central flow path 121c and an eccentric flow path 121e.
[0104] More specifically, in the screw compressor 1 of modified examples 5 to 7 shown in Figures 9 to 11, the first flow path 121 has a central flow path 121c provided at the center of the radial RD of the rotating shaft 12 and communicating with the lubrication chamber LC, and an eccentric flow path 121e provided eccentrically outside the center of the radial RD of the rotating shaft 12 and communicating with the central flow path 121c.
[0105] With this configuration, the lubricating fluid L flowing from the lubrication chamber LC into the central channel 121c of the first channel 121 is subjected to centrifugal force directed outward in the radial direction RD of the first channel 121 due to the rotation of the rotating shaft 12. This centrifugal force allows the lubricating fluid L to flow and be pumped from the central channel 121c into the eccentric channel 121e, which is positioned eccentrically to the radial direction RD outward from the center of the rotating shaft 12. Therefore, the flow rate of the lubricating fluid L supplied from the bottom 14b of the upstream space US of the casing 14 to the downstream space DS via the supply passage 17, the lubrication chamber LC, and the first channel 121 can be increased.
[0106] Preferred embodiments and variations of the present disclosure have been described in detail above. However, the present disclosure is not limited to the embodiments and variations described above. Various modifications or substitutions may be applied to the embodiments and variations described above without departing from the scope of the present disclosure. Furthermore, features described separately can be combined as long as no technical inconsistencies arise.
[0107] For example, in the modified examples shown in Figures 5 to 11, an example in which the screw compressor 1 is equipped with a centrifugal pump mechanism 18 has been described, but the screw compressor 1 may be equipped with a pump mechanism other than the centrifugal pump mechanism 18. Specifically, the screw compressor 1 may be equipped with a trochoid pump or a yoke pump at the end of the rotating shaft 12 that pumps lubricating fluid L from the lubrication chamber LC to the first flow path 121 by the rotation of the rotating shaft 12. In addition, the screw compressor 1 may be equipped with a pump mechanism that pumps lubricating fluid L from the bottom 14b of the casing 14 to the supply passage 17. [Explanation of symbols]
[0108] 1. Screw compressor 10 Refrigeration equipment 11 Compression mechanism 111 Screw Rotor 12 Rotation axes 121 First channel 121a 1st opening 121b 2nd opening 121c Central channel 121e Eccentric channel 122 Second channel 122a 1st outlet 123 Third channel 123a 2nd outlet 124 Fourth channel 124a 3rd outlet 13 Motors 131 Rotor 132c coil end 14 Casing 141 Suction chamber 142 Motor Room 143 Rotor chamber 144 Discharge chamber 14b bottom 15A First bearing 15B Second bearing 15r rolling element 15s space 16. Sealing member 17 Supply route 18. Centrifugal pump mechanism 18b Suction hole 18c Closure member 18c1 1st suction passage 18c2 2nd suction passage 18r annular member 18h through hole AD Axial direction d1 Inner diameter d2 inner diameter DS downstream space L Lubricant LC lubrication chamber R refrigerant US upstream space
Claims
1. A compression mechanism (11) having a screw rotor (111) for compressing a refrigerant (R), The screw rotor (111) is fixed to a rotating shaft (12), A motor (13) having a rotor (131) fixed to the rotating shaft (12), A casing (14) having an intake chamber (141) for drawing in refrigerant (R) from the outside, a motor chamber (142) adjacent to the intake chamber (141) for housing the motor (13), a rotor chamber (143) adjacent to the motor chamber (142) for housing the compression mechanism (11), and a discharge chamber (144) for discharging the refrigerant (R) compressed by the compression mechanism (11) to the outside, A first bearing (15A) is provided in the casing (14) in the upstream space (US) formed by the motor chamber (142) and the suction chamber (141) upstream of the motor (13) in the flow of the refrigerant (R), and supports the rotating shaft (12). A sealing member (16) separates the upstream space (US) from the lubrication chamber LC surrounding the first bearing (15A), The device comprises a supply passage (17) connecting the bottom (14b) of the casing (14) where the lubricating fluid (L) is stored to the lubrication chamber (LC), The aforementioned rotating shaft (12) is A first flow path (121) communicates with the lubrication chamber (LC) and extends along the axial direction AD of the rotating shaft (12), The device has a second flow path (122) that communicates with the first flow path (121) and extends in a direction intersecting the axial direction (AD), and communicates with the downstream space (DS) formed by the motor chamber (142) and the rotor chamber (143) downstream of the rotor (131) in the flow of the refrigerant (R), Screw compressor (1).
2. The second flow path (122) has a first discharge port (122a) provided on the outer circumferential surface of the rotating shaft (12) inside the coil end (132c) of the motor (13), The screw compressor (1) according to claim 1.
3. The rotating shaft (12) has a third flow path (123) that communicates with the first flow path (121) and extends in a direction intersecting the axial direction (AD), and communicates with the motor chamber (142) upstream of the rotor (131) in the flow of the refrigerant (R). The third flow path (123) has a second discharge port (123a) provided on the outer circumferential surface of the rotating shaft (12) inside the coil end (132c) of the motor (13), The screw compressor (1) according to claim 1.
4. The downstream space (DS) further comprises a second bearing (15B) provided in the casing (14) and supporting the rotating shaft (12), The rotating shaft (12) has a fourth flow path (124) that communicates with the first flow path (121) and extends in a direction intersecting the axial direction (AD) to communicate with the downstream space (DS). The fourth flow path (124) has a third outlet (124a) for supplying the lubricating fluid (L) to the second bearing (15B). The screw compressor (1) according to claim 1.
5. The system further includes a centrifugal pump mechanism (18) that draws the lubricating fluid (L) from the lubrication chamber (LC) into the first flow path (121) by the rotation of the rotating shaft (12). The screw compressor (1) according to claim 1.
6. The first flow path (121) has a first opening (121a) provided on the axial end face (AD) of the rotating shaft (12) and opening into the lubrication chamber (LC), and a second opening (121b) provided on the outer circumferential surface of the rotating shaft (12) and opening into the lubrication chamber (LC), The centrifugal pump mechanism (18) has a closing member (18c) that closes the first opening (121a), The screw compressor (1) according to claim 5.
7. The closing member (18c) has a first intake passage (18c1) that communicates with the second opening (121b) and extends radially (RD) along the rotating shaft (12), and a second intake passage (18c2) that communicates with the first intake passage (18c1) and the first flow path (121) and extends axially (AD). The inner diameter (d2) of the second intake passage (18c2) is smaller than the inner diameter (d1) of the first flow path (121). The screw compressor (1) according to claim 6.
8. The centrifugal pump mechanism (18) has an annular member (18r) positioned at the axial end (AD) of the first flow path (121), The annular member (18r) has a smaller diameter than the first flow path (121) and has an intake hole (18b) that communicates with the first flow path (121) and the lubrication chamber (LC). The screw compressor (1) according to claim 5.
9. The annular member (18r) is arranged along the end face of the first bearing (15A) in the axial direction (AD) and has a plurality of through holes (18h) that communicate with the space (15s) in which the rolling elements 15r of the first bearing (15A) are housed and the lubrication chamber (LC). The screw compressor (1) according to claim 8.
10. The first flow path (121) includes a central flow path (121c) located at the center of the radial direction (RD) of the rotating shaft (12) and communicating with the lubrication chamber (LC), and an eccentric flow path (121e) located eccentrically outside the center in the radial direction (RD) and communicating with the central flow path (121c). The screw compressor (1) according to claim 5.
11. The lubricating fluid (L) is refrigerant oil. The screw compressor (1) according to claim 1.
12. A refrigeration apparatus (10) comprising a screw compressor (1) according to any one of claims 1 to 11.