Screw compressor and gas compression equipment

Abstract

This screw compressor comprises: a screw rotor; a bearing for rotatably supporting the screw rotor; a casing for housing the screw rotor and the bearing; and a labyrinth seal ring that is provided between a compression chamber in which the screw rotor is housed and a bearing chamber in which the bearing is housed, wherein the labyrinth seal ring is retained in the casing in a manner allowing the same to move in a radial direction in accordance with displacement of the shaft center of the screw rotor.

Description

Screw Compressor and Gas Compression Equipment

[0001] The present disclosure relates to a screw compressor and gas compression equipment.

[0002] In a screw compressor, gas (compressed gas) may leak from the compression chamber to the bearing chamber due to the pressure difference between the compression chamber and the bearing chamber. The bearing chamber is connected to the compression chamber on the suction side. When gas leakage from the compression chamber to the bearing chamber occurs as described above, the leaked gas expands and occupies the volume of the suction-side compression chamber, resulting in a decrease in suction efficiency. Or, since the leaked gas will be recompressed, surplus power is generated. Thus, gas leakage from the compression chamber to the bearing chamber leads to a decrease in the efficiency of the compressor. Therefore, in order to reduce such gas leakage, a labyrinth structure is provided between the compression chamber and the bearing chamber.

[0003] Patent Document 1 describes an oil-cooled screw compressor provided with a rotor shaft to which a spacer having a labyrinth structure is attached. The spacer is provided so as to be located between the rotor chamber (compression chamber) and the bearing chamber, and the labyrinth groove provided on the outer peripheral surface of the spacer prevents leakage of compressed gas from the rotor chamber to the bearing chamber.

[0004] Japanese Patent No. 7539828

[0005] By the way, in a screw compressor, when the axial center of the screw rotor is displaced due to a change in the rotational speed or the like, the gap between the rotor shaft and the casing expands in a region on the opposite side of the displacement direction of the axial center of the screw rotor with respect to the axial center, and gas leakage from the compression chamber to the bearing chamber is likely to occur.

[0006] In view of the above circumstances, at least one embodiment of the present invention aims to provide a screw compressor and gas compression equipment capable of effectively suppressing gas leakage from the compression chamber to the bearing chamber.

[0007] A screw compressor according to at least one embodiment of the present invention comprises: a screw rotor; a bearing for rotatably supporting the screw rotor; a casing for housing the screw rotor and the bearing; and a labyrinth seal ring provided between a compression chamber housing the screw rotor and a bearing chamber housing the bearing, wherein the labyrinth seal ring is held within the casing so as to be radially movable in accordance with the displacement of the axial center of the screw rotor.

[0008] Furthermore, a gas compression system according to at least one embodiment of the present invention comprises: a screw compressor configured to compress gas; an oil separator for separating oil from a mixture of compressed gas and oil discharged from the screw compressor; and an oil supply line for supplying the oil from the oil separator to the labyrinth seal ring.

[0009] According to at least one embodiment of the present invention, a screw compressor and gas compression equipment are provided that can effectively suppress gas leakage from the compression chamber to the bearing chamber.

[0010] This is a schematic diagram of a gas compression system according to one embodiment. This is a schematic cross-sectional view in plan of a screw compressor according to one embodiment. This is a schematic cross-sectional view showing an enlarged portion of the screw compressor according to one embodiment that includes the labyrinth seal ring. This is a schematic cross-sectional view showing an enlarged portion of the screw compressor according to one embodiment that includes the labyrinth seal ring.

[0011] Hereinafter, several embodiments of the present invention will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0012] (Configuration of the gas compression equipment) Figure 1 is a schematic diagram of a gas compression equipment including a screw compressor according to several embodiments. As shown in the figure, the gas compression equipment 1 comprises a screw compressor 2, an oil separator 4, a cooler 6, and a pump 8.

[0013] The screw compressor 2 is configured to compress and discharge the inhaled gas. In the figure, the symbol Ps indicates the suction pressure of the screw compressor 2, and the symbol Pd indicates the discharge pressure of the screw compressor 2. Oil is supplied to the screw compressor 2 via the oil supply line 10 for cooling and lubrication. The oil supplied to the screw compressor 2 is discharged together with the compressed gas.

[0014] The oil separator 4 is configured to separate oil from the mixture of compressed gas and oil discharged from the screw compressor 2. The oil separated in the oil separator 4 is supplied back to the screw compressor 2 via the oil supply line 10. Typically, the oil separated in the oil separator 4 is pressurized by the pump 8 before being supplied to the screw compressor 2 via the oil supply line 10. In this case, the oil pressure Poil supplied to the screw compressor 2 is higher than the discharge pressure Pd (Poil = Pd + α). Alternatively, the oil separated in the oil separator 4 may be cooled by the cooler 6 before being pressurized by the pump 8. Alternatively, the oil separated in the oil separator 4 may be cooled by the cooler 6 and then supplied to the screw compressor via the oil supply line 10' at a differential pressure without going through the pump 8.

[0015] (Configuration of the screw compressor) Figure 2 is a schematic cross-sectional view in plan view of a screw compressor according to one embodiment. The screw compressor 2 shown in Figure 2 is a twin screw compressor comprising a pair of screw rotors (male rotor 15 and female rotor 17) including a pair of rotor shafts 14 and 16, and a casing 12 that houses the pair of screw rotors. In other embodiments, the screw compressor may be a single screw compressor comprising one screw rotor including a rotor shaft and a casing that houses the screw rotor.

[0016] The rotor shafts 14 and 16 are rotatably supported by radial bearings 18A and 18B and a thrust bearing 20, respectively. Each bearing is supplied with oil from a pressure pot via an oil supply line 10. Each bearing is housed in a bearing chamber formed inside the casing 12. In the screw compressor 2 shown in Figure 2, the pair of radial bearings 18B (discharge-side radial bearings) are each housed in a bearing chamber 19. Each bearing may be a rolling bearing or a sliding bearing.

[0017] The male rotor 15 and the female rotor 17 have interlocking helical teeth. The interlocking of the teeth of the male rotor 15 and the female rotor 17, along with the casing 12, forms multiple tooth groove spaces (chambers) along the axial direction of the rotor shafts 14 and 16. The male rotor 15 and the female rotor 17 are housed in a compression chamber 13 formed inside the casing 12.

[0018] The rotor shaft 14 constituting the male rotor 15 is connected to the output shaft of a motor (not shown) and is configured to be rotationally driven by the motor. The female rotor 17, which meshes with the male rotor 15, is rotationally driven by the rotation of the male rotor 15. The female rotor 17 rotates in the opposite direction to the rotation of the male rotor 15. When the male rotor 15 and the female rotor 17 rotate while meshed, the tooth groove space moves axially from the suction side to the discharge side.

[0019] The oil supplied to the bearings and shaft seals (not shown) is discharged from the casing 12 and returned to the relatively low-pressure space of the screw rotor housing in the casing 12 via the return line 28. The oil supply lines to each bearing and shaft seal branching off from the oil supply line 10, and the return lines 28 from each part, may include external lines provided outside the casing 12, or internal lines provided inside the casing.

[0020] Gas is drawn into the aforementioned tooth groove space from the intake space 50 formed within the casing 12 via the intake port 52. As the male rotor 15 and female rotor 17 rotate, the tooth groove space moves axially from the intake side to the discharge side in accordance with the rotation of these screw rotors. In this process, once the intake port 52 is closed, the volume of the tooth groove space decreases, and the gas in the tooth groove space is compressed. When the tooth groove space reaches the discharge port 54 and communicates with the discharge space (not shown) formed in the casing 12, the compressed gas in the tooth groove space is discharged into the discharge space. The discharge port 54 is formed by an opening provided on the end face of the casing 12.

[0021] In some embodiments, the screw compressor 2 includes a labyrinth seal ring 60 provided in the axial direction between the compression chamber 13 and the discharge-side bearing chamber. In the exemplary embodiment shown in Figure 2, a labyrinth seal ring 60 is provided between the compression chamber 13 and the bearing chamber 19 housing the discharge-side radial bearing 18B that supports the rotor shaft 14 of the male rotor 15, and also between the compression chamber 13 and the bearing chamber 19 housing the discharge-side radial bearing 18B that supports the rotor shaft 16 of the female rotor 17. These labyrinth seal rings 60 are held within the casing 12 so as to be radially movable in accordance with the displacement of the axial center of the screw rotor (male rotor 15 or female rotor 17) corresponding to the labyrinth seal ring 60.

[0022] Figures 3 and 4 are schematic cross-sectional views showing enlarged portions of a screw compressor 2, including the labyrinth seal ring 60, according to one embodiment. Although Figures 3 and 4 illustrate the labyrinth seal ring 60 provided between the rotor shaft 14 and the casing 12 of the male rotor 15, a similar configuration can be applied to the labyrinth seal ring 60 provided between the rotor shaft 16 and the casing 12 of the female rotor 17.

[0023] As shown in Figures 2 to 4, the labyrinth seal ring 60 includes an annular member provided on the outer circumference of the rotor shaft 14 and the inner circumference of the casing 12 in the radial direction of the rotor shaft 14. The labyrinth seal ring 60 is a separate component from the rotor and casing and can move independently of the rotor and casing. Gaps are formed between the inner surface of the labyrinth seal ring 60 and the outer surface of the rotor shaft 14 in the radial direction, and between the outer surface of the labyrinth seal ring 60 and the inner surface of the casing 12 in the radial direction. (Note that in Figures 3 and 4, the outer surface of the labyrinth seal ring 60 and the inner surface of the casing 12 are shown in contact, but in reality, a small gap is formed between them.)

[0024] The inner circumferential surface of the labyrinth seal ring 60 is provided with a plurality of annular protrusions (for example, the first annular protrusion 62 and the second annular protrusion 64 in Figures 3 and 4) that project radially inward, and the irregularities formed on the inner circumferential surface of the labyrinth seal ring 60 by the plurality of annular protrusions constitute a labyrinth structure. As a result, the fluid flow from the compression chamber 13 toward the bearing chamber 19 is reduced.

[0025] As shown in Figures 3 and 4, in some embodiments, the screw compressor 2 includes an adjacent member 72 provided adjacent to the labyrinth seal ring 60 in the axial direction. The adjacent member 72 is provided adjacent to the labyrinth seal ring 60 in the axial direction, on the opposite side of the compression chamber 13 from the labyrinth seal ring 60.

[0026] In the exemplary embodiments shown in Figures 3 and 4, the adjacent member 72 is an annular member provided axially between the radial bearing 18B (see Figure 2) and the labyrinth seal ring 60, and has a flange portion 72a projecting radially inward. In other embodiments, the adjacent member adjacent to the labyrinth seal ring 60 may include a bearing (the outer ring or housing of the bearing).

[0027] In some embodiments, the screw compressor 2 includes a pin 76 fixed to either the labyrinth seal ring 60 or an adjacent member 72, and a notch 74 provided on the other of the labyrinth seal ring 60 or adjacent member 72 (i.e., the one of the labyrinth seal ring 60 or adjacent member 72 to which the pin 76 is not fixed), which accommodates a portion of the pin 76. The pin 76 is provided such that its central axis is aligned with the axial direction of the rotor shaft 14. The size (length) D2 of the notch 74 in the radial direction of the rotor shaft 14 is greater than the diameter D1 of the pin 76.

[0028] In the exemplary embodiment shown in Figure 3, the screw compressor 2 includes a pin 76 fixed to a labyrinth seal ring 60 and a notch 74 provided in an adjacent member 72. The pin 76 is partially inserted into a hole 61 provided in the labyrinth seal ring 60 and is fixed to the labyrinth seal ring 60 by means of interference fit, screw fastening, etc. The notch 74 is provided so as to be recessed radially outward from the inner circumferential surface of the adjacent member 72. The exposed portion of the pin 76 (the portion not inserted into the hole 61) is accommodated in the notch 74 of the adjacent member 72.

[0029] In the exemplary embodiment shown in Figure 4, the screw compressor 2 includes a pin 76 fixed to an adjacent member 72 and a notch 74 provided in the labyrinth seal ring 60. The pin 76 is partially inserted into a hole 73 provided in the adjacent member 72 and is fixed to the adjacent member 72 by means of interference fit, screw fastening, etc. The notch 74 is provided so as to be recessed radially inward from the outer circumferential surface of the labyrinth seal ring 60. The exposed portion of the pin 76 (the portion not inserted into the hole 73) is housed in the notch 74 of the labyrinth seal ring 60.

[0030] In a screw compressor, if gas leaks from the compression chamber to the bearing chamber due to the pressure difference between the compression chamber and the bearing chamber, the efficiency of the compressor decreases because the volume of the compression space decreases due to the expansion of the leaked gas as it flows into the intake side of the compression chamber along with the discharge of the oil supplied to the bearing chamber, and the compression of gas that does not contribute to the gas cycle (re-compression of leaked gas) occurs. Here, if a labyrinth seal is installed between the compression chamber and the bearing chamber of the screw compressor, gas leakage can be suppressed by narrowing the clearance of the labyrinth seal (the gap between the rotor shaft side and the casing side). On the other hand, if the labyrinth seal is fixed to the rotor shaft or casing, the labyrinth seal and the casing or rotor shaft are more likely to come into contact when the rotor shaft is displaced.

[0031] In this regard, in the above-described configuration, the labyrinth seal ring 60 is held within the casing 12 so as to be able to move radially in accordance with the displacement of the axis of the screw rotor (male rotor 15, etc.). More specifically, as described above, for example, the radial size D2 of the notch 74 provided on the other side of the labyrinth seal ring 60 or the adjacent member 72 is larger than the diameter D1 of the pin 76 fixed to one of the labyrinth seal ring 60 or the adjacent member 72. Therefore, with a portion of the pin 76 housed in the notch 74, the labyrinth seal ring 60 is able to move radially between the rotor shaft 14 and the casing 12. Thus, since the labyrinth seal ring 60 can move radially in accordance with the displacement of the axis of the screw rotor (male rotor 15), the gap can be kept narrow even if the axis of the screw rotor is displaced. Therefore, while suppressing contact between the rotor shaft 14 and the labyrinth seal, gas leakage from the compression chamber 13 to the bearing chamber 19 can be effectively suppressed.

[0032] In some embodiments, the pin 76 may serve as an anti-rotation mechanism for the labyrinth seal ring 60. For this reason, the circumferential width of the notch 74, which accommodates a portion of the pin 76, may be slightly larger than the diameter D1 of the pin 76.

[0033] Furthermore, the size D2 of the radial notch 74 may be larger than the circumferential width of the notch 74. This allows for moderate restriction of the circumferential movement of the labyrinth seal ring 60 while facilitating its radial movement.

[0034] In some embodiments, the adjacent member 72 is provided to restrict the axial movement of the labyrinth seal ring 60.

[0035] For example, the adjacent member 72 may receive an axial force from the outer ring of the radial bearing 18B (see Figure 2) directed toward the intake side, thereby pressing the adjacent member 72 against the casing 12 in the axial direction, and determining the position of the adjacent member 72 relative to the casing 12 in the axial direction. Furthermore, as shown in Figures 3 and 4, for example, the labyrinth seal ring 60 may be housed in an annular space surrounded by the casing 12, the flange portion 72a of the adjacent member 72, and the rotor shaft 14. The radial bearing 18B may be fixed to the casing 12 by a bolt (not shown) whose central axis is aligned with the axial direction of the rotor shaft 14. The axial force acting on the adjacent member 72 from the outer ring of the radial bearing 18B may be the axial force of the bolt.

[0036] In some embodiments, the plurality of annular protrusions provided on the inner circumferential surface of the labyrinth seal ring 60 include at least one first annular protrusion 62 provided on the compression chamber 13 side in the axial direction, at least one second annular protrusion 64 provided on the bearing chamber 19 side in the axial direction, and an oil pocket 66 located between the at least one first annular protrusion 62 and the at least one second annular protrusion 64 in the axial direction. Oil is supplied to the oil pocket 66.

[0037] By supplying oil to the oil pocket 66, oil is retained in the labyrinth formed by the first annular protrusion 62 and the second annular protrusion 64, thereby obstructing the flow of gas from the compression chamber 13 to the bearing chamber 19. Therefore, gas leakage from the compression chamber 13 to the bearing chamber 19 can be suppressed more effectively.

[0038] In some embodiments, the number of second annular protrusions 64 is greater than the number of first annular protrusions 62. In the exemplary embodiments shown in Figures 3 and 4, the labyrinth seal ring 60 includes two first annular protrusions 62 and four second annular protrusions 64. That is, the number of second annular protrusions 64 is greater than the number of first annular protrusions 62.

[0039] When oil at a pressure approximately equal to the discharge pressure of the screw compressor 2 is supplied to the oil pocket 66, the pressure difference between the oil pocket 66 and the bearing chamber 19 tends to be greater than the pressure difference between the oil pocket 66 and the compression chamber 13. As described above, by increasing the number of second annular protrusions 64 on the bearing chamber 19 side, where the pressure difference with the oil pocket 66 is relatively large, to more than the number of first annular protrusions 62 on the compression chamber 13 side, the outflow of oil from the oil pocket 66 can be effectively suppressed.

[0040] In some embodiments, oil discharged from the screw compressor 2 along with the compressed gas may be supplied to the oil pocket 66. For example, oil (pressure: Poil) from an oil separator 4 (see Figure 1) into which oil discharged from the screw compressor 2 along with the compressed gas is guided may be supplied to the oil pocket 66 of the labyrinth seal ring 60 via an oil supply line 10 (see Figure 2). As shown in Figures 2 to 4, the oil from the oil supply line 10 may be supplied to the oil pocket 66 via an internal passage 80 provided in the casing 12.

[0041] As shown in Figures 3 and 4, in some embodiments, the labyrinth seal ring 60 may include an oil passage 68 that is recessed radially inward from the outer circumferential surface of the labyrinth seal ring 60, and a connecting passage 70 that connects the oil passage 68 to the oil pocket 66. Oil from the oil supply line 10 may be supplied to the oil pocket 66 via the internal passage 80, the oil passage 68, and the connecting passage 70.

[0042] The oil passage 68 may be an annular groove extending along the circumferential direction of the rotor shaft 14. The communication passage 70 may be provided so as to extend along the radial direction of the rotor shaft 14. Further, the labyrinth seal ring 60 may include a plurality of communication passages 70 provided so as to be spaced apart in the circumferential direction.

[0043] As shown in FIGS. 3 and 4, the screw compressor 2 may include an O-ring 78 provided between the casing 12 and the labyrinth seal ring 60 in the axial direction.

[0044] In some embodiments, for example, as shown in FIGS. 3 and 4, the adjacent member 72, the labyrinth seal ring 60, and the O-ring 78 may be arranged in this order in the axial direction. By arranging them in such a manner, the labyrinth seal ring 60 pushed toward the bearing chamber side by the restoring force of the O-ring 78 can be appropriately received by the adjacent member 72.

[0045] In some embodiments, for example, as shown in FIGS. 3 and 4, the O-ring 78 is provided radially outside the inner end 68a (or bottom surface) in the radial direction of the oil passage 68.

[0046] Since the oil passage 68 is supplied with oil at a higher pressure (pressure: Poil) than the compression chamber 13 and bearing chamber 19, an axial force acts on the labyrinth seal ring 60 in accordance with the pressure difference at the pressure-receiving portion (the axial end faces 60a, 60b of the labyrinth seal ring 60 and the side wall faces 69a, 69b of the oil passage 68). In this respect, with the above configuration, since the O-ring 78 is provided radially outward from the inner end 68a of the oil passage 68 in the radial direction, the force acting on the labyrinth seal ring 60 in the axial direction toward the compression chamber 13, based on the pressure difference between the axial end face 60a of the labyrinth seal ring 60 (the axial end face on the compression chamber 13 side) and the side wall face 69a of the oil passage 68 that face the casing 12, can be increased to a certain extent. This reduces the opposing axial force acting on the labyrinth seal ring 60 (force from the labyrinth seal ring 60 toward the bearing chamber 19; force arising from the pressure difference between the axial end face 60b of the labyrinth seal ring 60 facing the adjacent member 72 (the axial end face on the bearing chamber 19 side) and the side wall surface 69b of the oil passage 68). In other words, it is possible to suppress excessive force pressing the labyrinth seal ring 60 toward the adjacent member 72. Therefore, inappropriate axial movement of the components of the screw compressor (such as bearing components) becomes less likely.

[0047] In some embodiments, as shown in Figure 2, for example, the screw compressor 2 is equipped with a pair of labyrinth seal rings 60 corresponding to a pair of screw rotors (male rotor 15 and female rotor 17), and each of the pair of labyrinth seal rings 60 is provided with an annular oil passage 68 (see Figures 3 and 4). In addition, an internal passage 82 is formed in the casing 12 that connects the oil passage 68 on the male rotor 15 side and the oil passage 68 on the female rotor 17 side.

[0048] According to the above-described embodiment, since the internal passage 82 that connects the oil passages 68 of the pair of labyrinth seal rings 60 is provided in the casing 12, by supplying oil from the outside of the casing 12 to the oil passage 68 of one of the labyrinth seal rings 60 (the labyrinth seal ring 60 on the male rotor 15 side in FIG. 2), oil can also be supplied to the oil passage 68 of the other labyrinth seal ring 60 (the labyrinth seal ring 60 on the female rotor 17 side in FIG. 2). That is, according to the above-described configuration, oil can be supplied to both of the pair of labyrinth seal rings 60 with a simple configuration.

[0049] In some embodiments, the oil from the oil supply line 10 may be supplied to the oil passages 68 of the labyrinth seal ring 60 on the male rotor 15 side and the labyrinth seal ring 60 on the female rotor 17 side, respectively, through separate internal passages formed in the casing 12.

[0050] The content described in each of the above embodiments is understood as follows, for example.

[0051] [1] The screw compressor (2) according to at least one embodiment of the present invention includes: a screw rotor (for example, male rotor 15 or female rotor 17); a bearing (for example, radial bearing 18B) for rotatably supporting the screw rotor; a casing (12) for housing the screw rotor and the bearing; and a labyrinth seal ring (60) provided between a compression chamber (13) in which the screw rotor is housed and a bearing chamber (19) in which the bearing is housed. The labyrinth seal ring is held in the casing so as to be movable in the radial direction in accordance with the displacement of the axial center of the screw rotor.

[0052] When a labyrinth seal is installed between the compression chamber and the bearing chamber of a screw compressor, narrowing the clearance of the labyrinth seal (the gap between the rotor shaft side and the casing side) can suppress gas leakage. On the other hand, if the labyrinth seal is fixed to the rotor shaft or casing, the labyrinth seal and the casing or rotor shaft are more likely to come into contact when the rotor shaft is displaced. According to the configuration in [1] above, the labyrinth seal ring is movable radially in accordance with the displacement of the axis center of the screw rotor, so the gap can be kept narrow even if the axis center of the screw rotor is displaced due to changes in rotational speed, etc. Therefore, it is possible to effectively suppress gas leakage from the compression chamber to the bearing chamber while suppressing contact between the rotor shaft and the labyrinth seal.

[0053] [2] In some embodiments, the configuration of [1] above, the labyrinth seal ring includes: at least one first annular projection (62) provided on the compression chamber side; at least one second annular projection (64) provided on the bearing chamber side; and an oil pocket (66) located in the axial direction between the at least one first annular projection and the at least one second annular projection.

[0054] According to the configuration described in [2] above, the labyrinth seal ring is provided with a first annular projection and a second annular projection, and an oil pocket located between the first annular projection and the second annular projection. By supplying oil to the oil pocket, oil is retained in the labyrinth formed by the first annular projection and the second annular projection. This obstructs the flow of gas from the compression chamber to the bearing chamber, and thus more effectively suppresses gas leakage from the compression chamber to the bearing chamber.

[0055] [3] In some embodiments, in the configuration of [2] above, the number of at least one second annular protrusion is greater than the number of at least one first annular protrusion.

[0056] When oil at a pressure similar to the compressor's discharge pressure is supplied to the oil pocket, the pressure difference between the oil pocket and the bearing chamber tends to be greater than the pressure difference between the oil pocket and the compression chamber. According to the configuration in [3] above, the number of second annular protrusions on the bearing chamber side, where the pressure difference with the oil pocket is relatively large, is greater than the number of first annular protrusions on the compression chamber side, so the outflow of oil from the oil pocket can be effectively suppressed.

[0057] [4] In some embodiments, in the configuration of [2] or [3] above, the screw compressor is configured such that oil discharged from the screw compressor together with the compressed gas is supplied to the oil pocket.

[0058] According to the configuration described in [4] above, high-pressure oil discharged into the oil pocket along with the compressed gas is supplied to the oil pocket, so the oil is more easily retained in the labyrinth formed by the first and second annular protrusions. Therefore, the flow of gas from the compression chamber to the bearing chamber can be more effectively inhibited, and thus gas leakage from the compression chamber to the bearing chamber can be more effectively suppressed.

[0059] [5] In some embodiments, in any of the configurations [1] to [4] above, the screw compressor comprises: a pin (76) fixed to the labyrinth seal ring or to one of the adjacent members adjacent to the labyrinth seal ring in the axial direction; and a notch (74) provided in the other of the labyrinth seal ring or the adjacent member, which accommodates a part of the pin, wherein the size (D2) of the notch in the radial direction is greater than the diameter (D1) of the pin.

[0060] According to the configuration in [5] above, the radial size of the notch provided in the other of the labyrinth seal ring or adjacent member is larger than the diameter of the pin fixed to the labyrinth seal ring or adjacent member. Therefore, with a portion of the pin housed in the notch, the labyrinth seal ring can move radially between the rotor and the casing. Thus, as described in [1] above, the labyrinth seal ring can move radially in accordance with the displacement of the screw rotor's axis, so the gap can be kept narrow even if the screw rotor's axis is displaced. Therefore, contact between the rotor shaft and the labyrinth seal can be suppressed while effectively preventing gas leakage from the compression chamber to the bearing chamber.

[0061] [6] In some embodiments, in the configuration of [5] above, the size of the notch in the circumferential direction is larger than the diameter of the pin.

[0062] According to the configuration described in [6] above, the circumferential size of the notch provided on the other side of the labyrinth seal ring or adjacent member is larger than the diameter of the pin fixed to the labyrinth seal ring or adjacent member. As a result, the labyrinth seal ring can move circumferentially between the rotor and the casing with a portion of the pin housed in the notch. Therefore, the labyrinth seal ring can move radially and circumferentially in accordance with the displacement of the screw rotor's axis. This allows the gap to be kept narrow even if the screw rotor's axis is displaced, by the labyrinth seal ring following the rotor axis. Thus, gas leakage from the compression chamber to the bearing chamber can be more effectively suppressed while preventing contact between the rotor axis and the labyrinth seal.

[0063] [7] In some embodiments, in any of the configurations of [1] to [6] above, the screw compressor comprises: an adjacent member (72) adjacent to the labyrinth seal ring in the axial direction and provided to restrict the position of the labyrinth seal ring in the axial direction; and an O-ring (78) provided between the casing and the labyrinth seal ring in the axial direction, wherein the adjacent member, the labyrinth seal ring and the O-ring are arranged in this order in the axial direction.

[0064] According to the configuration described in [7] above, the adjacent member, the labyrinth seal ring, and the O-ring are arranged in this order in the axial direction, so that the labyrinth seal ring 60, which is being pushed toward the bearing chamber side by the restoring force of the O-ring 78, can be properly received by the adjacent member 72.

[0065] [8] In some embodiments, in the configuration of [2] above, the screw compressor includes an O-ring (78) provided between the casing and the labyrinth seal ring in the axial direction, the labyrinth seal ring includes an oil passage (68) provided recessed from the outer circumferential surface of the labyrinth seal ring and through which oil for supplying to the oil pocket is guided, and a communication passage (70) connecting the oil passage and the oil pocket, wherein the O-ring is provided radially outward from the radial inner end (68a) of the oil passage.

[0066] According to the configuration described in [8] above, since the O-ring is provided radially outward from the inner end of the oil passage in the radial direction, the force acting on the labyrinth seal ring 60 in the axial direction toward the compression chamber 13 can be increased to some extent based on the pressure difference between the axial end face of the labyrinth seal ring (the face facing the casing) and the side wall surface of the oil passage. This reduces the opposing force acting on the labyrinth seal ring 60 in the axial direction (the force toward the bearing chamber 19 from the labyrinth seal ring 60; the force generated based on the pressure difference between the axial end face 60b of the labyrinth seal ring 60 facing the adjacent member 72 (the axial end face on the bearing chamber 19 side) and the side wall surface 69b of the oil passage 68). In other words, it is possible to suppress the force pressing the labyrinth seal ring 60 toward the adjacent member 72 from becoming excessive. Therefore, inappropriate axial movement of the components of the screw compressor (such as bearing components) becomes less likely.

[0067] [9] In some embodiments, in any of the configurations of [1] to [8] above, the screw compressor comprises: a pair of screw rotors (male rotor 15 and female rotor 17); a pair of bearings for rotatably supporting the pair of screw rotors; and a pair of labyrinth seal rings provided between a compression chamber housing the pair of screw rotors and a pair of bearing chambers housing the pair of bearings, respectively, wherein the casing is configured to house the pair of screw rotors and the pair of bearings, and each of the pair of labyrinth seal rings includes an annular oil passage recessed from the outer circumferential surface of the labyrinth seal ring, and the screw compressor comprises an internal passage (82) provided in the casing that connects the oil passage of one of the pair of labyrinth seal rings to the oil passage of the other of the pair of labyrinth seal rings.

[0068] According to the configuration of [9] above, an internal passage is provided in the casing that connects the oil passages of a pair of labyrinth seal rings. Therefore, by supplying oil to the oil passage of one labyrinth seal ring from outside the casing, oil can also be supplied to the oil passage of the other labyrinth seal ring. In other words, according to the configuration of [9] above, oil can be supplied to both of a pair of labyrinth seal rings with a simple configuration.

[0069]

[10] A gas compression system (1) according to at least one embodiment of the present invention comprises: a screw compressor (2) according to any one of [1] to [9] above, configured to compress gas; an oil separator (4) for separating oil from a mixture of compressed gas and oil discharged from the screw compressor; and an oil supply line (10) for supplying the oil from the oil separator to the labyrinth seal ring.

[0070] According to the configuration of

[10] above, the labyrinth seal ring is movable radially in accordance with the displacement of the screw rotor's axis, so that the gap can be kept narrow even if the axis of the screw rotor is displaced due to changes in rotational speed, etc. Therefore, it is possible to effectively suppress gas leakage from the compression chamber to the bearing chamber while suppressing contact between the rotor shaft and the labyrinth seal. Furthermore, according to the configuration of

[10] above, high-pressure oil discharged together with the compressed gas is supplied to the labyrinth seal ring, so that oil is easily retained in the labyrinth of the labyrinth seal ring, and for this reason, the flow of gas from the compression chamber to the bearing chamber can be effectively obstructed. Therefore, gas leakage from the compression chamber to the bearing chamber can be suppressed more effectively.

[0071] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0072] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances sufficient to achieve the same function. For example, expressions describing things being in an equal state such as "identical," "equal," and "homogeneous" shall not only describe states of being strictly equal, but also describe states where tolerances or differences exist to the extent that the same function is achieved. Furthermore, in this specification, expressions describing shapes such as quadrilaterals or cylindrical shapes shall not only describe geometrically precise quadrilaterals or cylindrical shapes, but also describe shapes including concave and convex parts or chamfered parts to the extent that the same effect is achieved. In addition, in this specification, expressions such as "equipment," "includes," or "possesses" a component are not exclusive expressions that exclude the existence of other components.

[0073] 1 Gas compression equipment 2 Screw compressor 4 Oil separator 6 Cooler 8 Pump 10, 10' Oil supply line 12 Casing 13 Compression chamber 14 Rotor shaft 15 Male rotor 16 Rotor shaft 17 Female rotor 18A, 18B Radial bearing 19 Bearing chamber 20 Thrust bearing 28 Return line 50 Intake space 52 Intake port 54 Discharge port 60 Labyrinth seal ring 60a, 60b Axial end face 61 Hole 62 First annular projection 64 Second annular projection 66 Oil pocket 68 Oil passage 68a Inner end 69a, 69b Side wall surface 70 Connecting passage 72 Adjacent member 72a Flange portion 73 Hole 74 Notch 76 Pin 78 O-ring 80 Internal passage 82 Internal passage

Claims

1. A screw compressor comprising: a screw rotor; a bearing for rotatably supporting the screw rotor; a casing for housing the screw rotor and the bearing; and a labyrinth seal ring provided between a compression chamber housing the screw rotor and a bearing chamber housing the bearing, wherein the labyrinth seal ring is held within the casing so as to be radially movable in accordance with the displacement of the axial center of the screw rotor.

2. The screw compressor according to claim 1, wherein the labyrinth seal ring comprises at least one first annular projection provided on the compression chamber side, at least one second annular projection provided on the bearing chamber side, and an oil pocket located in the axial direction between the at least one first annular projection and the at least one second annular projection.

3. The screw compressor according to claim 2, wherein the number of at least one second annular protrusion is greater than the number of at least one first annular protrusion.

4. The screw compressor according to claim 2 or 3, configured such that oil discharged from the screw compressor together with compressed gas is supplied to the oil pocket.

5. A screw compressor according to any one of claims 1 to 3, comprising: a pin fixed to the labyrinth seal ring or to one of the adjacent members adjacent to the labyrinth seal ring in the axial direction; and a notch provided in the other of the labyrinth seal ring or the adjacent member, which accommodates a portion of the pin, wherein the size of the notch in the radial direction is greater than the diameter of the pin.

6. The screw compressor according to claim 5, wherein the size of the notch in the circumferential direction is greater than the diameter of the pin.

7. A screw compressor according to any one of claims 1 to 3, comprising: an adjacent member provided adjacent to the labyrinth seal ring in the axial direction and to restrict the position of the labyrinth seal ring in the axial direction; and an O-ring provided between the casing and the labyrinth seal ring in the axial direction, wherein the adjacent member, the labyrinth seal ring and the O-ring are arranged in this order in the axial direction.

8. The screw compressor according to claim 2, further comprising an O-ring provided between the casing and the labyrinth seal ring in the axial direction, wherein the labyrinth seal ring includes an oil passage provided recessed from the outer circumferential surface of the labyrinth seal ring, through which oil for supplying to the oil pocket is guided, and a connecting passage connecting the oil passage and the oil pocket, wherein the O-ring is provided radially outward from the radially inner end of the oil passage.

9. A screw compressor according to any one of claims 1 to 3, comprising: a pair of screw rotors; a pair of bearings for rotatably supporting the pair of screw rotors; and a pair of labyrinth seal rings provided between a compression chamber housing the pair of screw rotors and a pair of bearing chambers housing the pair of bearings, wherein the casing is configured to house the pair of screw rotors and the pair of bearings; each of the pair of labyrinth seal rings includes an annular oil passage recessed from the outer circumferential surface of the labyrinth seal ring; and the casing includes an internal passage connecting the oil passage of one of the pair of labyrinth seal rings to the oil passage of the other of the pair of labyrinth seal rings.

10. A gas compression apparatus comprising: a screw compressor according to any one of claims 1 to 3, configured to compress gas; an oil separator for separating oil from a mixture of compressed gas and oil discharged from the screw compressor; and an oil supply line for supplying the oil from the oil separator to the labyrinth seal ring.

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