Screw compressors and refrigeration systems

Abstract

This disclosure provides a screw compressor capable of suppressing the temperature rise of the motor that rotates the screw rotor of a compression mechanism that compresses a refrigerant. [Solution] The screw compressor 1 comprises a compression mechanism 11, a rotating shaft 12, a motor 13, a casing 14, bearings 15A and 15B, a sealing member 16, a supply passage 17, and a discharge passage 18. The sealing member 16 separates the low-pressure space LPS of the casing 14 from the lubrication chamber LC surrounding the bearings 15A and 15B. The supply passage 17 supplies lubricating fluid L to the lubrication chamber LC. The discharge passage 18 discharges the lubricating fluid L that has passed through the bearings 15A and 15B from the lubrication chamber LC to the coil end 132c of the motor 13 adjacent to the screw rotor 111 of the compression mechanism 11.

Description

Technical Field

[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 (for example, see Patent Document 1). In the compressor described in Patent Document 1, a motor and a compression rotor of a compression part are arranged horizontally in a casing in order from the suction port side.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional compressor described in Patent Document 1, the refrigerant flows horizontally to cool the motor and is compressed by the compression rotor in the compression part. Therefore, the temperature of the refrigerant rises on the downstream side rather than the upstream side of the motor, and the temperature difference from the motor decreases. As a result, the temperature of the motor tends to rise on the downstream side of the refrigerant flow.

[0005] The present disclosure provides a screw compressor and a refrigeration device capable of suppressing a temperature rise of a motor that rotates a screw rotor of a compression mechanism for compressing a refrigerant.

Means for Solving the Problems

[0006] A first aspect of the present disclosure is a casing (14) having a screw rotor (111) and a compression mechanism (11) for compressing a refrigerant (R), a rotating shaft (12) to which the screw rotor (111) is fixed, a motor (13) for rotating 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. The screw compressor (1) comprises: bearings (15A, 15B) provided in the low-pressure space (LPS) from the intake chamber (141) to the rotor chamber (143) to support the rotating shaft (12); a sealing member (16) that separates the low-pressure space (LPS) from the lubrication chamber (LC) surrounding the bearings (15A, 15B); a supply passage (17) for supplying lubricating fluid (L) to the lubrication chamber (LC); and a discharge passage (18) for discharging the lubricating fluid (L) that has passed through the bearings (15A, 15B) from the lubrication chamber (LC) to the coil end (132c) of the motor (13) adjacent to the screw rotor (111).

[0007] According to the first embodiment described above, a screw compressor (1) is provided that can suppress the temperature rise of the motor (13) that rotates the screw rotor (111) of the compression mechanism (11) that compresses the refrigerant (R).

[0008] A second aspect of the present disclosure is a screw compressor (1) in which, in the first aspect, the discharge passage (18) has one or more outlets (18e) around the coil end (132c) for discharging the lubricating fluid (L) toward the coil end (132c).

[0009] In the second embodiment described above, lubricating fluid (L) is discharged toward the coil end (132c) from the outlet (18e) of the discharge passage (18) provided around the coil end (132c) adjacent to the screw rotor (111) downstream of the rotor (131) of the motor (13). As a result, even if the temperature difference between the refrigerant (R), whose temperature has risen due to cooling the motor (13), and the coil end (132c) decreases downstream of the flow of refrigerant (R) in the motor chamber (142), the coil end (132c) can be cooled by the lubricating fluid (L) discharged from the outlet (18e). Furthermore, if the discharge passage (18) has multiple outlets (18e), the motor (13) can be cooled more effectively by discharging the lubricating fluid (L) toward the coil end (132c) from multiple outlets (18e).

[0010] A third aspect of the present disclosure is a screw compressor (1) in which, in the first or second aspect described above, the intake chamber (141) has an intake port (14a) that opens upward, the rotating shaft (12) is arranged horizontally, and the discharge passage (18) has one or more discharge ports (18e) that are provided above the coil end (132c) and discharge the lubricating fluid (L) toward the coil end (132c).

[0011] In the third embodiment described above, the refrigerant (R) is drawn in from the intake port (14a) into the intake chamber (141), flows downward, and then flows horizontally through the motor chamber (142), with a bias towards the lower side of the motor chamber (142). As a result, the temperature of the upper part of the coil end (132c) adjacent to the screw rotor (111) on the downstream side of the refrigerant (R) flow in the motor (13) tends to rise. However, by discharging lubricating fluid (L) from the outlet (18e) located above the coil end (132c), the temperature rise of the upper part of the coil end (132c) located on the downstream side of the refrigerant (R) flow can be suppressed, and the temperature rise of the motor (13) can be suppressed more effectively. Furthermore, the lubricating fluid (L) discharged from the outlet (18e) is drawn into the compression chamber between the compression mechanism (11) and the casing (14), thereby preventing excessive accumulation of lubricating fluid (L) at the bottom of the casing (14) and preventing insufficient lubrication of the compression mechanism (11).

[0012] A fourth aspect of the present disclosure is a screw compressor (1) in any one of the first to third aspects described above, wherein the supply passage (17) connects the bottom of the discharge chamber (144) to the lubrication chamber (LC), and supplies the refrigerant oil stored at the bottom of the discharge chamber (144) to the lubrication chamber (LC) as the lubricating fluid (L).

[0013] In the fourth embodiment described above, the differential pressure between the discharge chamber (144) and the lubrication chamber (LC) can be used to supply the refrigerant oil, which has been separated from the refrigerant (R) in the discharge chamber (144) and stored at the bottom of the discharge chamber (144), to the lubrication chamber (LC) as lubricant (L) via the supply passage (17). Furthermore, by discharging the refrigerant oil from the lubrication chamber (LC) to the coil end (132c) of the motor (13) via the discharge passage (18), the coil end (132c) of the motor (13) can be cooled with the refrigerant oil, which has a high cooling effect.

[0014] Furthermore, the refrigerant (R) in the discharge chamber (144), which is compressed and becomes high pressure by the compression mechanism (11), exerts pressure on the screw rotor (111), and a thrust load acts from the screw rotor (111) towards the bearings (15A, 15B) in the low-pressure space (LPS) on the rotating shaft (12). However, by supplying lubricating fluid (L) from the bottom of the discharge chamber (144), which is a high-pressure space (HPS) with a higher pressure than the low-pressure space (LPS), to the lubrication chamber (LC) via the supply passage (17), the thrust load acting from the screw rotor 111 on the rotating shaft (12) is offset by the pressure of the lubricating fluid (L) in the lubrication chamber LC. This reduces the thrust load acting on the bearings (15A, 15B) and extends the service life of the bearings (15A, 15B).

[0015] A fifth aspect of the present disclosure is a screw compressor (1) that further comprises, in any one of the first to third aspects described above, an inverter (191) that supplies power to the motor (13), and a cooling unit (192) that cools the inverter (191) by passing liquid coolant (R) through it, wherein the supply passage (17) connects the cooling unit (192) and the lubrication chamber (LC) and supplies the liquid coolant (R) that has passed through the cooling unit (192) to the lubrication chamber (LC).

[0016] In the fifth embodiment described above, liquid refrigerant (R) is supplied to the cooling unit 192, and the inverter (191) can be cooled by the cooling unit (192) cooled by the liquid refrigerant (R). Furthermore, the liquid refrigerant (R) that has passed through the cooling unit (192) is supplied to the lubrication chamber (LC) via the supply passage (17), and the bearings (15A, 15B) can be lubricated using the liquid refrigerant (R) as lubricating fluid (L). In addition, by supplying liquid refrigerant (R) to the bearings (15A, 15B), lubrication of the bearings (15A, 15B) becomes unnecessary, and overheating of the refrigerant (R) due to oil can be suppressed. Moreover, the liquid refrigerant (R) can be vaporized in the lubrication chamber (LC) to absorb heat from the surroundings. Furthermore, by discharging liquid coolant (R) from the lubrication chamber (LC) through the discharge passage (18) to the coil end (132c) of the motor (13), the coil end (132c) of the motor (13) can be cooled by the liquid coolant (R), which has a high cooling effect.

[0017] A sixth aspect of this disclosure is a screw compressor (1) in which, in the fifth aspect described above, the rolling elements (15r) of the bearings (15A, 15B) are made of ceramic. This configuration reduces the centrifugal force acting on the rolling elements (15r) when the rotating shaft (12) rotates, improves the lubrication characteristics of the rolling elements (15r), and allows the use of liquid refrigerant (R) as the lubricating fluid (L).

[0018] A seventh aspect of this disclosure is a screw compressor (1) in any one of the first to sixth aspects described above, wherein the supply passage (17) or the discharge passage (18) has an orifice (RO). This configuration allows for the control of the amount of lubricating fluid (L) in the lubrication chamber (LC) by limiting the flow rate of lubricating fluid (L) flowing into the lubrication chamber (LC) via the supply passage (17) or the flow rate of lubricating fluid (L) flowing out of the lubrication chamber (LC) via the discharge passage (18).

[0019] An eighth aspect of this disclosure is a refrigeration system (10) comprising a screw compressor (1) according to any one of the first to seventh aspects described above. According to this aspect, a refrigeration system (10) is provided that can suppress the temperature rise of the motor (13) that rotates the screw rotor (111) of a compression mechanism (11) that compresses a refrigerant (R). [Brief explanation of the drawing]

[0020] [Figure 1] A refrigerant circuit diagram showing embodiments of the refrigeration system (10) and screw compressor (1) of the present disclosure. [Figure 2] A graph showing the operating range of the screw compressor (1) according to the embodiment of Figure 1. [Figure 3] A perspective view of a screw compressor (1) according to the embodiment of Figure 1. [Figure 4] Cross-sectional view of the screw compressor (1) along line IV-IV in Figure 3. [Figure 5] An enlarged view of the vicinity of the bearing (15A) in the cross-sectional view of the screw compressor (1) in Figure 4. [Figure 6] An enlarged view corresponding to Figure 5, showing a modified example 1 of the screw compressor (1) in Figure 4. [Figure 7] An enlarged view corresponding to FIG. 5 showing a second modification of the screw compressor (1) in FIG. 4. [Figure 8] A cross-sectional view of the screw compressor (1) taken along line VIII-VIII in FIG. 3. [Figure 9] A cross-sectional view of the screw compressor (1) taken along line IX-IX in FIG. 3.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the screw compressor (1) and the refrigeration device (10) according to the present disclosure will be described with reference to the drawings.

[0022] FIG. 1 is a refrigerant circuit diagram showing an embodiment of the refrigeration device 10 and the screw compressor 1 according to the present disclosure. The refrigeration device 10 of the present embodiment includes a screw compressor 1. Specifically, the refrigeration device 10 is, for example, a water heater or a chiller unit. Further, the refrigeration device 10 may be, for example, an air conditioner.

[0023] The refrigeration device 10 has a refrigerant circuit 2 filled with a refrigerant R and performs a vapor compression refrigeration cycle. The refrigerant circuit 2 includes, for example, a screw compressor 1, a radiator 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 FIG. 1, the solid arrows indicate the flow of the refrigerant R in the refrigerant circuit 2, and the dotted lines indicate the electrical connections between the controller 9 and each part.

[0024] The screw compressor 1 includes a generally cylindrical casing 14 provided with a suction port 14a and a discharge port 14e. Although details will be described later, the screw compressor 1 compresses the refrigerant R in a low-pressure gas state inhaled from the suction port 14a and discharges the refrigerant R in a high-pressure gas state from the discharge port 14e.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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 lower SST and higher SDT operating range 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. For example, the screw compressor 1 of this embodiment includes an operating range in which the compression ratio is 7 or higher. For example, the screw compressor 1 of this embodiment includes an operating range in which the SST is less than 25°C. For example, the screw compressor 1 of this embodiment includes an operating range in which the STD is greater than 68°C, or a region in which the STD is greater than 75°C.

[0030] Figure 3 is a perspective view showing an example of a screw compressor 1 according to the embodiment of Figure 1. Figure 4 is a cross-sectional view of the screw compressor 1 along the line IV-IV in Figure 3. As described above, the screw compressor 1 comprises a generally cylindrical casing 14 provided with an inlet 14a and a discharge port 14e, 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.

[0031] The screw compressor 1 comprises a compression mechanism 11, a rotating shaft 12, a motor 13, a casing 14, a bearing 15A, a sealing member 16, a supply passage 17, and a discharge passage 18. In the example shown in Figure 4, the screw compressor 1 further comprises a bearing 15B located in the middle of the rotating shaft 12, and a bearing 15C located at the other end of the rotating shaft 12, in addition to the bearing 15A located at one end of the rotating shaft 12. The screw compressor 1 may also further comprise an inverter unit 19.

[0032] 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 cooling capacity of the motor 13 by the refrigerant R decreases, and the temperature of the motor 13 tends to rise.

[0033] Furthermore, the refrigerant R is drawn in through the upward-opening intake port 14a, flows downward towards the bottom of the casing 14, and then flows horizontally. As a result, the refrigerant R flowing horizontally within the casing 14 is biased towards the bottom of the casing 14. In addition, the refrigerant R flows horizontally, cooling the motor 13, and is compressed by the screw rotor 111 in the compression mechanism 11. Therefore, the temperature of the refrigerant R rises more downstream of the motor 13 than upstream, and the temperature difference with the motor 13 decreases. Consequently, the temperature of the motor 13 tends to rise more easily at the coil end 132c, which is downstream and above the flow of the refrigerant R.

[0034] The following describes in detail the configuration of each part of the screw compressor 1 that solves the aforementioned problems.

[0035] As shown in Figure 4, 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 Figures 3 and 4, 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.

[0036] The intake chamber 141 draws in refrigerant R from the outside. Specifically, the intake chamber 141 has an intake port 14a that opens upward. The intake port 14a is located at the upper end of the first portion 14A of the casing 14 that forms the intake chamber 141, and draws 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 portion 14A of the casing 14 also has a plurality of ribs 14r1 (see Figure 8) 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 a bearing 15A at their center.

[0037] The motor chamber 142 houses the motor 13 adjacent to the intake chamber 141. The motor 13 rotates the rotating shaft 12 to which the screw rotor 111 of the compression mechanism 11 is fixed. Specifically, the motor 13 has a rotor 131 fixed to the rotating shaft 12 and 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.

[0038] The motor chamber 142 has, for example, a cylindrical inner circumferential wall having a predetermined distance from the outer circumferential surface of the stator 132, and a plurality of protrusions that project inward from the inner circumferential 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 intervals in the circumferential direction of the inner circumferential wall of the motor chamber 142 and extend along the axial direction AD of the rotating shaft 12.

[0039] In the example shown in Figure 4, 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 4, the inverter unit 19 is not shown, and the schematic shapes of each part of the inverter unit 19 are shown by dashed lines.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Furthermore, a lubricating fluid storage chamber 14d is provided at the bottom of the discharge chamber 144. The lubricating fluid storage chamber 14d is mainly formed by the second portion 14B of the casing 14 and is located below the rotor chamber 143. The rotor chamber 143 and the lubricating fluid storage chamber 14d are separated by a partition wall provided in the second portion 14B of the casing 14. The cylindrical portion of the discharge chamber 144 formed in the third portion 14C of the casing 14 and the lubricating fluid storage chamber 14d at the bottom of the discharge chamber 144 formed in the second portion 14B are in communication via a passage provided in the third portion 14C. The lubricating fluid storage chamber 14d stores, for example, refrigerating oil as a lubricating fluid L separated from the refrigerant R in the discharge chamber 144.

[0046] 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 bearing 15B at their center. The second portion 14B of the casing 14 also supports the 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.

[0047] As described above, the first bearing 15A is supported in the center of the radial ribs 14r1 (see Figure 8) provided on the first portion 14A of the casing 14. The bearing 15A is located in the low-pressure space LPS from the intake chamber 141 to the rotor chamber 143 and rotatably supports the end of the rotating shaft 12 on the intake port 14a side. In the example shown in Figure 3, the low-pressure space LPS of the casing 14 is located upstream of the flow of the refrigerant R from the compression chamber formed between the compression mechanism 11 and the second portion 14B of the casing 14.

[0048] 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 is located in the low-pressure space LPS, rotatably supporting the intermediate portion of the rotating shaft 12 in the axial direction AD. The third bearing 15C is supported in the second portion 14B of the casing 14 via a support member 14s and is located in the low-pressure space LPS, rotatably supporting the end of the rotating shaft 12 on the discharge port 14e side. The rotating shaft 12 is located inside the casing 14, along the horizontal direction.

[0049] Figure 5 is an enlarged view of the vicinity of the bearing 15A in the screw compressor 1 of Figure 4. In the example shown in Figure 5, a plurality of ribs 14r1 (see Figure 8) arranged radially around the rotating shaft 12 have an opening 14o in the center that supports the bearing holder 14c. The bearing holder 14c is coaxial with the rotating shaft 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.

[0050] 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 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 bearing 15A and the bottom wall of the bearing holder 14c, which becomes part of the lubrication chamber LC.

[0051] The sealing member 16 is provided to partition the low-pressure space LPS of the casing 14 from the lubrication chamber LC. In the example shown in Figure 5, 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 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.

[0052] In the example shown in Figure 5, the sealing member 16 is, for example, a labyrinth seal having a plurality of irregularities on its inner surface facing the outer surface of the rotating shaft 12. The sealing member 16 is positioned, for example, between a step provided on the inner surface of a cylindrical opening 14o provided in the center of the radial rib 14r1 and an annular plate 16p fixed to the outside of the opening 14o. The annular plate 16p is fixed to the center of the radial rib 14r1, with the rotating shaft 12 inserted through a through hole in its center, and supports the sealing member 16 from the outside of the opening 14o. Note that the sealing member 16 separating the low-pressure space LPS of the casing 14 from the lubrication chamber LC is not limited to a labyrinth seal.

[0053] Figure 6 is an enlarged view corresponding to Figure 5, showing a modified example 1 of the screw compressor 1 of Figure 4. In the example shown in Figure 6, the sealing member 16L that separates the low-pressure space LPS of the casing 14 from the lubrication chamber LC is a lip seal. The sealing member 16L has, for example, an elastic annular sealing lip 16s and a cylindrical sealing housing 16h that supports the sealing lip 16s.

[0054] Figure 7 is an enlarged view corresponding to Figure 5, showing a modified example 2 of the screw compressor (1) of Figure 4. In the example shown in Figure 7, the sealing member 16T that separates the low-pressure space LPS of the casing 14 from the lubrication chamber LC is a tip seal. The sealing member 16T has, for example, an annular inner ring 16r and a cylindrical seal housing 16h. The inner ring 16r is positioned on the outer circumferential surface of the rotating shaft 12 by inserting the rotating shaft 12 through a through hole in the center of the inner ring 16r.

[0055] The seal housing 16h is a cylindrical member having a large diameter section and a small diameter section, through which the rotating shaft 12 is inserted. The large diameter section has an inner diameter larger than the outer diameter of the inner ring 16r and houses the inner ring 16r inside. The small diameter section has an inner diameter smaller than the outer diameter of the inner ring 16r and larger than the inner diameter of the inner ring 16r. The inner ring 16r is positioned between the step between the large diameter section and the small diameter section of the seal housing 16h and the annular plate 16p.

[0056] The space between the outer circumferential surface of the inner ring 16r and the inner circumferential surface of the large-diameter portion of the seal housing 16h is connected to the lubrication chamber LC via a through hole 16b provided in the seal housing 16h. As a result, lubricating fluid L is introduced from the lubrication chamber LC into the space between the inner ring 16r and the seal housing 16h, and the pressure of the lubricating fluid L acts on the outer circumferential surface of the inner ring 16r, sealing the space between the inner circumferential surface of the inner ring 16r and the outer circumferential surface of the rotating shaft 12.

[0057] Furthermore, the screw compressor 1 may have a sealing member 16 that separates the low-pressure space LPS from the lubrication chamber LC surrounding the bearing 15B, similar to the examples shown in Figures 5 to 7. In this case, the screw compressor 1 may have a supply passage 17 that supplies lubricating fluid L to the lubrication chamber LC surrounding the bearing 15B, and a discharge passage 18 that discharges the lubricating fluid L from the lubrication chamber LC to the coil end 132c of the motor 13 adjacent to the screw rotor 111. Alternatively, the discharge passage 18 may discharge the lubricating fluid L to the coil end 132c of the motor 13 located upstream of the flow of the refrigerant R.

[0058] As shown in Figures 5 to 7, the supply passage 17 supplies lubricating fluid L to the lubrication chamber LC. Specifically, as shown in Figure 4, for example, the supply passage 17 connects the bottom of the discharge chamber 144 to the lubrication chamber LC and supplies the refrigerant oil stored at the bottom of the discharge chamber 144 to the lubrication chamber LC as the lubricating fluid L. More specifically, as shown in Figures 4 and 5, the supply passage 17 connects the lubricating fluid storage chamber 14d at the bottom of the discharge chamber 144 to the lubrication chamber LC via a passage provided in the casing 14 and a passage provided in the bearing holder 14c. The supply passage 17 has, for example, a first to a sixth section.

[0059] The first portion of the supply passage 17 is provided in the second portion 14B of the casing 14, communicates with the lubricating fluid storage chamber 14d at the bottom of the discharge chamber 144, and extends in the axial direction AD of the rotating shaft 12. The second portion of the supply passage 17 is provided in the second portion 14B of the casing 14, communicates with the first portion of the supply passage 17, and extends in the radial direction RD of the rotating shaft 12. The third portion of the supply passage 17 is provided in the second portion 14B of the casing 14, communicates with the second portion of the supply passage 17, and extends in the axial direction AD of the rotating shaft 12.

[0060] The fourth portion of the supply passage 17 is provided in the first portion 14A of the casing 14 and communicates with the third portion of the supply passage 17, extending in the axial direction AD of the rotating shaft 12. The fifth portion of the supply passage 17 is provided in the first portion 14A of the casing 14 and communicates with the fourth portion of the supply passage 17, extending in the radial direction RD of the rotating shaft 12. The sixth portion of the supply passage 17 is provided in the bearing holder 14c and communicates with the fifth portion of the supply passage 17, extending in the radial direction RD of the rotating shaft 12 and communicating with the lubrication chamber LC. As shown in Figures 5 to 7, the inner diameter of the sixth portion of the supply passage 17 provided in the bearing holder 14c is smaller than the inner diameter of the fifth portion of the supply passage 17 provided in the first portion 14A of the casing 14.

[0061] In this configuration, the bottom of the discharge chamber 144 of the casing 14 and the lubrication chamber LC are in communication via the supply passage 17. The discharge chamber 144 of the casing 14 is a high-pressure space HPS located downstream of the refrigerant R flow in the compression chamber formed between the compression mechanism 11 and the casing 14. Furthermore, the low-pressure space LPS, located upstream of the refrigerant flow in the compression chamber, and the lubrication chamber LC are separated by sealing members 16, 16L, and 16T.

[0062] Figure 8 is a cross-sectional view of screw compressor 1 along the line VIII-VIII in Figure 3. Figure 9 is a cross-sectional view of screw compressor 1 along the line IX-IX in Figure 3.

[0063] As shown in Figures 4 to 9, the discharge passage 18 discharges the lubricating fluid L that has passed through the bearing 15A from the lubrication chamber LC to the coil end 132c of the motor 13 adjacent to the screw rotor 111. The discharge passage 18 has, for example, an inlet 18a that opens into the lubrication chamber LC and an outlet 18e that opens into the inner wall surface of the casing 14 facing the coil end 132c of the motor 13.

[0064] Specifically, the discharge passage 18 has, for example, a first to a third section. As shown in Figure 8, the first section of the discharge passage 18 communicates with the lubrication chamber LC via an inlet 18a, passes through a rib 14r1 provided on the first section 14A of the casing 14, and is connected to a connecting section 18b provided on the outer circumferential surface of the first section 14A. The second section of the discharge passage 18 is composed of, for example, a connecting pipe 18t connected to the connecting section 18b.

[0065] Although not shown in Figures 3 and 4, the connecting pipe 18t that constitutes the second part of the discharge passage 18 connects a connecting portion 18b that opens to the outer surface of the first part 14A of the casing 14 and a connecting portion 18c that opens to the outer surface of the second part 14B of the casing 14. The second part of the discharge passage 18 may also be a passage provided in the first part 14A and the second part 14B of the casing 14, similar to the supply passage 17, to connect the first and third parts of the discharge passage 18.

[0066] As shown in Figure 4, the third portion of the discharge passage 18 connects a connecting portion 18c provided on the outer surface of the second portion 14B of the casing 14 to a discharge port 18e provided on the inner circumferential wall of the motor chamber 142. The discharge port 18e is located downstream of the flow of refrigerant R in the motor chamber 142 and faces the coil end 132c of the motor 13. Thus, the discharge passage 18 has, for example, one or more discharge ports 18e around the coil end 132c of the motor 13 adjacent to the screw rotor 111, which discharge the lubricating fluid L toward the coil end 132c.

[0067] Furthermore, in the example shown in Figure 9, the discharge passage 18 has one or more outlets 18e provided above the coil end 132c and discharges the lubricating fluid L toward the coil end 132c. Specifically, in the example shown in Figure 9, the third portion of the discharge passage 18 has three outlets 18e provided above the outer surface of the coil end 132c, two outlets 18e provided on the sides of the outer surface of the coil end 132c, and two outlets 18e provided below the outer surface of the coil end 132c. The position and number of outlets 18e provided around the coil end 132c are not particularly limited.

[0068] More specifically, in the example shown in Figure 9, the third portion of the discharge passage 18 is connected to a connection portion 18c that opens onto the outer surface of the second portion 14B of the casing 14, and extends in a grid pattern vertically and horizontally along a plane perpendicular to the axial direction AD of the rotating shaft 12. The third portion of the discharge passage 18 also has a plurality of discharge ports 18e provided around the coil end 132c of the motor 13, which is located downstream of the flow of the refrigerant R in the motor chamber 142.

[0069] In the example shown in Figure 9, the third portion of the discharge passage 18 has multiple openings including connecting portions 18c on the outer surface of the second portion 14B of the casing 14, and each opening except for the connecting portions 18c is closed by a closing member 18d. The third portion of the discharge passage 18 may also have multiple connecting portions 18c opening on the outer surface of the second portion 14B of the casing 14. In this case, each connecting portion 18c may be connected to the first portion of the discharge passage 18 provided in the first portion 14A of the casing 14 via a connecting pipe 18t or the second portion of the discharge passage 18 provided in the second portion 14B of the casing 14.

[0070] The operation of the screw compressor 1 and refrigeration system 10 of this embodiment will be described below.

[0071] 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.

[0072] 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 and flows into the lubricating liquid storage chamber 14d at the bottom of the discharge chamber 144 where it is stored.

[0073] 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.

[0074] 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 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 cooling capacity of the motor 13 by the refrigerant R decreases, and the temperature of the motor 13 tends to rise. In particular, since the temperature of the refrigerant R rises more downstream of the motor 13 than upstream, the temperature of the motor 13 tends to rise at the coil end 132c located downstream of the flow of the refrigerant R. As a means of solving these problems, the screw compressor 1 in this embodiment has the following configuration.

[0075] The screw compressor 1 has a screw rotor 111, a compression mechanism 11 for compressing the refrigerant R, a rotating shaft 12 to which the screw rotor 111 is fixed, and a motor 13 for rotating the rotating shaft 12. The screw compressor 1 also includes a casing 14, bearings 15A, 15B, a sealing member 16, a supply passage 17, and a discharge passage 18. The casing 14 has an intake chamber 141, a motor chamber 142, a rotor chamber 143, and a discharge chamber 144. The intake chamber 141 draws in the refrigerant R from the outside. The motor chamber 142 houses the motor 13 adjacent to the intake chamber 141. The rotor chamber 143 houses the compression mechanism 11 adjacent to the motor chamber 142. The discharge chamber 144 discharges the refrigerant R compressed by the compression mechanism 11 to the outside. The bearings 15A and 15B are located in the low-pressure space LPS from the intake chamber 141 to the rotor chamber 143 and support the rotating shaft 12. The sealing member 16 separates the low-pressure space LPS from the lubrication chamber LC surrounding the bearings 15A and 15B. The supply passage 17 supplies lubricating fluid L to the lubrication chamber LC. The discharge passage 18 discharges the lubricating fluid L that has passed through the bearings 15A and 15B from the lubrication chamber LC to the coil end 132c of the motor 13 adjacent to the screw rotor 111.

[0076] With this configuration, lubricating fluid L is supplied to the lubrication chamber LC via the supply passage 17 to lubricate the bearings 15A and 15B, and the lubricating fluid L that has passed through the bearings 15A and 15B can be discharged from the lubrication chamber LC via the discharge passage 18 to the coil end 132c of the motor 13 adjacent to the screw rotor 111. As a result, even if the flow rate of the refrigerant R decreases as the operating range of the screw compressor 1 is expanded, the coil end 132c can be cooled by the lubricating fluid L downstream of the flow of refrigerant R, where the temperature of the motor 13 tends to rise. Therefore, according to the screw compressor 1 of this embodiment, the coil end 132c of the motor 13 adjacent to the screw rotor 111 can be effectively cooled, and the operating range can be expanded compared to conventional designs. In addition, since the lubricating fluid L discharged from the discharge port 18e does not pass through the rotor 131 of the motor 13, agitation of the lubricating fluid L by the rotor 131 is suppressed, and the efficiency of the motor 13 is improved.

[0077] Furthermore, in the screw compressor 1 of this embodiment, the discharge passage 18 has one or more discharge ports 18e around the coil end 132c that discharge lubricating fluid L toward the coil end 132c.

[0078] With this configuration, lubricating fluid L is discharged from the outlet 18e of the discharge passage 18, which is located downstream of the rotor 131 of the motor 13 in the flow of the refrigerant R, towards the coil end 132c adjacent to the screw rotor 111. As a result, even if the temperature difference between the refrigerant R, whose temperature has risen due to cooling the motor 13, and the coil end 132c decreases downstream of the flow of the refrigerant R in the motor chamber 142, the coil end 132c can still be cooled by the lubricating fluid L discharged from the outlet 18e. Furthermore, if the discharge passage 18 has multiple outlets 18e, the motor 13 can be cooled more effectively by discharging the lubricating fluid L towards the coil end 132c from multiple outlets 18e.

[0079] Furthermore, in the screw compressor 1 of this embodiment, the intake chamber 141 has an intake port 14a that opens upward. The rotating shaft 12 is arranged horizontally. The discharge passage 18 is provided above the coil end 132c adjacent to the screw rotor 111 and has one or more discharge ports 18e that discharge lubricating fluid L toward the coil end 132c.

[0080] With this configuration, the refrigerant R is drawn in from the intake port 14a into the intake chamber 141, flows downward, and then flows horizontally through the motor chamber 142, with a bias towards the lower side of the motor chamber 142. As a result, the temperature of the upper part of the coil end 132c adjacent to the screw rotor 111 on the downstream side of the refrigerant R flow in the motor 13 tends to rise. However, by discharging lubricating fluid L from the outlet 18e located above the coil end 132c, the temperature rise of the upper part of the coil end 132c located on the downstream side of the refrigerant R flow can be suppressed, and the temperature rise of the motor 13 can be suppressed more effectively. In addition, the lubricating fluid L discharged from the outlet 18e is drawn into the compression chamber between the compression mechanism 11 and the casing 14, which prevents excessive accumulation of lubricating fluid L at the bottom of the casing 14 and prevents insufficient lubrication of the compression mechanism 11.

[0081] Furthermore, in the screw compressor 1 of this embodiment, the supply passage 17 connects the bottom of the discharge chamber 144 to the lubrication chamber LC, and supplies the refrigerant oil stored at the bottom of the discharge chamber 144 to the lubrication chamber LC as lubricating fluid L.

[0082] With this configuration, the bottom of the discharge chamber 144, which is a high-pressure space (HPS), and the motor chamber 142, which is a low-pressure space (LPS) where the motor 13 is located, are connected via the supply passage 17, the lubrication chamber LC, and the discharge passage 18. This allows the differential pressure between the discharge chamber 144 and the lubrication chamber LC to be used to supply the refrigerant oil, which has been separated from the refrigerant R in the discharge chamber 144 and stored at the bottom of the discharge chamber 144, as lubricant L to the lubrication chamber LC via the supply passage 17, thereby lubricating the bearings 15A and 15B. Furthermore, the differential pressure between the lubrication chamber LC and the motor chamber 142 allows the lubricant L to be sprayed from the discharge passage 18 towards the coil end 132c of the motor 13. This enables the coil end 132c of the motor 13 to be cooled with refrigerant oil, which has a high cooling effect.

[0083] Furthermore, pressure is applied to the screw rotor 111 from the refrigerant R in the discharge chamber 144, which has been compressed to a high pressure by the compression mechanism 11, and a thrust load is applied from the screw rotor 111 to the rotating shaft 12 toward the bearings 15A and 15B in the low-pressure space LPS. However, by supplying lubricating fluid L from the bottom of the discharge chamber 144, which is the high-pressure space HPS, to the lubrication chamber LC via the supply passage 17, the thrust load acting from the screw rotor 111 to the rotating shaft 12 is offset by the pressure of the lubricating fluid L in the lubrication chamber LC. This reduces the thrust load acting on the bearings 15A and 15B in the low-pressure space LPS, and extends the service life of the bearings 15A and 15B.

[0084] Furthermore, the refrigeration system 10 of this embodiment is equipped with the aforementioned screw compressor 1. Therefore, according to the refrigeration system 10 of this embodiment, the temperature rise of the motor 13 that rotates the screw rotor 111 of the compression mechanism 11 of the screw compressor 1 that compresses the refrigerant R can be suppressed, and the operating range of the screw compressor 1 can be expanded to the range shown by the solid line in Figure 2.

[0085] As described above, this embodiment provides a screw compressor 1 and a refrigeration system 10 that can suppress the temperature rise of the motor 13 that rotates the screw rotor 111 of the compression mechanism 11 that compresses the refrigerant R. Note that the screw compressor and refrigeration system according to this disclosure are not limited to the configuration of the screw compressor 1 and refrigeration system 10 of the above-described embodiment. Hereinafter, modifications of the screw compressor 1 according to the above-described embodiment will be described.

[0086] In the screw compressor 1 according to the above embodiment, an example was described in which refrigerant oil is used as the lubricating fluid L, but the lubricating fluid L is not limited to refrigerant oil. As described above, the screw compressor 1 further includes an inverter 191 that supplies power to the motor 13, and a cooling unit 192 that cools the inverter 191 by passing a refrigerant R in a liquid state (hereinafter referred to as "liquid refrigerant R") through it. In this case, the supply passage 17 may connect the cooling unit 192 and the lubrication chamber LC, and the liquid refrigerant R that has passed through the cooling unit 192 may be supplied to the lubrication chamber LC.

[0087] With this configuration, liquid refrigerant R is supplied to the cooling unit 192, and the inverter 191 that supplies power to the motor 13 can be cooled by the cooling unit 192 cooled by the liquid refrigerant R. In addition, the liquid refrigerant R that has passed through the cooling unit 192 is supplied to the lubrication chamber LC via the supply passage 17, and the liquid refrigerant R can be used as a lubricant L to lubricate the bearings 15A and 15B. Furthermore, by supplying liquid refrigerant R to the bearings 15A and 15B, lubrication of the bearings 15A and 15B becomes unnecessary, and overheating of the refrigerant R due to oil can be suppressed. In addition, the liquid refrigerant R can be vaporized in the lubrication chamber LC to absorb heat from the surroundings. Furthermore, by discharging the liquid coolant R from the lubrication chamber LC to the coil end 132c of the motor 13 via the discharge passage 18, the coil end 132c of the motor 13 can be cooled by the liquid coolant R, which has a high cooling effect. The supply passage 17 connecting the liquid coolant R flow path of the cooling unit 192 to the lubrication chamber LC can be provided, for example, in the second part 14B of the casing 14 where the cooling unit 192 is located, and in the first part 14A of the casing 14 including the rib 14r1.

[0088] Furthermore, when using liquid refrigerant R as lubricant L in the screw compressor 1, ceramic rolling elements 15r can be used for bearings 15A and 15B. This configuration reduces the centrifugal force acting on the rolling elements 15r when the rotating shaft 12 rotates, improves the lubrication characteristics of the rolling elements 15r, and allows liquid refrigerant R to be used as lubricant L.

[0089] Furthermore, as shown in Figure 4, the screw compressor 1 may have an orifice RO in the supply passage 17. Although not shown in the figure, the discharge passage 18 may have an orifice RO instead of the supply passage 17. With this configuration, the amount of lubricating fluid L in the lubrication chamber LC can be adjusted by limiting the flow rate of lubricating fluid L flowing into the lubrication chamber LC via the supply passage 17, or the flow rate of lubricating fluid L flowing out of the lubrication chamber LC via the discharge passage 18.

[0090] Preferred embodiments and variations thereof of this disclosure have been described in detail above. However, this disclosure is not limited to the embodiments and variations thereof described above. Various modifications or substitutions may be applied to the embodiments and variations thereof described above without departing from the scope of this disclosure. Furthermore, features described separately can be combined as long as no technical inconsistencies arise. [Explanation of Symbols]

[0091] 1. Screw compressor 10 Refrigeration equipment 11 Compression mechanism 111 Screw Rotor 12 Rotation axes 13 Motors 132c coil end 14 Casing 141 Suction chamber 142 Motor Room 143 Rotor chamber 144 Discharge chamber 15A bearing 15B bearing 16. Sealing member 17 Supply route 18 Exhaust channel 18e outlet 14a Inlet 191 Inverter 192 Cooling section 15r rolling element L Lubricant LC lubrication chamber LPS Low-Pressure Space R refrigerant RO Orifice

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) that rotates the aforementioned 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 bearing (15A, 15B) is provided in the low-pressure space (LPS) from the intake chamber (141) to the rotor chamber (143) and supports the rotating shaft (12), A sealing member (16) separates the low-pressure space (LPS) and the lubrication chamber (LC) surrounding the bearings (15A, 15B), A supply passage (17) for supplying lubricating fluid (L) to the lubrication chamber (LC), The system includes a discharge passage (18) that discharges the lubricating fluid (L) that has passed through the bearings (15A, 15B) from the lubrication chamber (LC) to the coil end (132c) of the motor (13) adjacent to the screw rotor (111), Screw compressor (1).

2. The discharge passage (18) has one or more outlets (18e) around the coil end (132c) that discharge the lubricating fluid (L) toward the coil end (132c). The screw compressor (1) according to claim 1.

3. The aforementioned intake chamber (141) has an intake port (14a) that opens upward, The aforementioned rotating shaft (12) is arranged along the horizontal direction, The discharge passage (18) is provided above the coil end (132c) and has one or more outlets (18e) for discharging the lubricating fluid (L) toward the coil end (132c). The screw compressor (1) according to claim 1.

4. The supply passage (17) connects the bottom of the discharge chamber (144) to the lubrication chamber (LC), and supplies the refrigerant oil stored at the bottom of the discharge chamber (144) to the lubrication chamber (LC) as the lubricating fluid (L). The screw compressor (1) according to claim 1.

5. The system further comprises an inverter (191) that supplies power to the motor (13), and a cooling unit (192) that cools the inverter (191) by passing liquid coolant (R) through it. The supply passage (17) connects the cooling unit (192) and the lubrication chamber (LC), and supplies the liquid refrigerant (R) that has passed through the cooling unit (192) to the lubrication chamber (LC). The screw compressor (1) according to claim 1.

6. The rolling elements (15r) of the bearings (15A, 15B) are made of ceramic. The screw compressor (1) according to claim 5.

7. The supply passage (17) or the discharge passage (18) has an orifice (RO). The screw compressor (1) according to claim 1.

8. A refrigeration apparatus (10) comprising a screw compressor (1) according to any one of claims 1 to 7.

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