Liquid-cooled screw compressor

Abstract

To improve the cooling performance and sealing performance of a liquid-cooled screw compressor.SOLUTION: A screw compressor 1 includes: at least one screw rotor 2 having a plurality of tooth spaces 4c; a rotor casing 5 having a rotor chamber 6 in which the screw rotor is housed; a liquid supply path 16 provided on the rotor casing 5 to supply liquid to the rotor chamber 6; and a plurality of liquid supply holes 21, 22 which have a smaller cross-sectional area than the liquid supply path 16, are connected to a downstream end part of the liquid supply path 16 in a liquid flow direction, and are open into on the rotor chamber 6. A center axis of the downstream end part of the liquid supply path 16 is defined as a reference axis A18. At least one of the center axes A21, A22 of the liquid supply holes 21, 22 extends at an inclination with respect to the reference axis A18 such that it is further away from the reference axial line A18 as it goes from a connection part with the liquid supply path 16 toward the rotor chamber 6. The center axes A21, A22 of the plurality of liquid supply holes 21, 22 extend so as not to cross with each other on a downstream side of the liquid flow direction.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a liquid-cooled screw compressor. [Background technology]

[0002] Patent Document 1 discloses a liquid-cooled screw compressor equipped with a rotor casing having a rotor chamber in which a pair of screw rotors are housed. For cooling and sealing purposes, the rotor casing is provided with a liquid supply hole for injecting liquid into the rotor chamber. The liquid supply hole extends radially from a branch point from a liquid supply line toward the central axis of the rotor chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-33993 Summary of the Invention [Problem to be solved by the invention]

[0004] When the liquid supply holes are arranged as described above, it is difficult for the liquid injected into the rotor chamber to reach the entire compression space. There is room for improvement in the cooling and sealing performance of liquid-cooled screw compressors.

[0005] An object of the present invention is to improve the cooling and sealing properties of a liquid-cooled screw compressor. [Means for solving the problem]

[0006] One aspect of the present invention provides a liquid-cooled screw compressor comprising: at least one screw rotor having a plurality of tooth grooves; a rotor casing having a rotor chamber in which the screw rotor is housed; a liquid supply passage provided in the rotor casing to supply liquid to the rotor chamber; and a plurality of liquid supply holes having a smaller cross-sectional area than the liquid supply passage, connected to the downstream end of the liquid supply passage in the liquid flow direction, and opening into the rotor chamber, wherein, when the central axis of the liquid supply passage at the downstream end is taken as a reference axis, the central axis of at least one of the liquid supply holes extends at an angle to the reference axis so as to move away from the reference axis from the connection with the liquid supply passage toward the rotor chamber, and the central axes of the plurality of liquid supply holes extend so as not to intersect with each other downstream in the liquid flow direction.

[0007] According to the above configuration, liquid is diverted from the liquid supply passage into multiple liquid supply holes and supplied to the rotor chamber from each of the multiple liquid supply holes. The central axis of at least one liquid supply hole extends at an angle with respect to the reference axis and away from the reference axis. This allows the liquid to be widely distributed throughout the compression space. Furthermore, the central axes of the multiple liquid supply holes extend so as not to intersect with each other downstream. This allows the liquid supplied into the rotor chamber from the multiple liquid supply holes to be widely distributed throughout the compression space without intersecting or colliding with each other.

[0008] The central axes of the plurality of liquid supply holes may all extend at an angle relative to the reference axis.

[0009] According to the above configuration, the liquid spreads more widely throughout the compression space.

[0010] At least one of the liquid supply holes may have a central axis extending parallel to the reference axis at a position spaced apart from the reference axis in a direction perpendicular to the reference axis.

[0011] According to the above-mentioned configuration, there are a mixture of liquid supply holes inclined with respect to the reference axis and liquid supply holes parallel to the reference axis. In this case, too, it is possible to widely distribute the liquid throughout the compression space.

[0012] The rotor casing may have a mounting hole that opens into the rotor chamber and communicates with the liquid supply path, and the liquid supply hole may be formed in a nozzle member that is separate from the rotor casing and attached to the mounting hole.

[0013] According to the above configuration, in contrast to the case where the fluid supply hole is directly machined in the rotor casing, the inclined fluid supply hole can be easily provided in the rotor casing.

[0014] The liquid supply path may include a common section that forms the upstream portion in the liquid flow direction, and a plurality of branch sections that branch off from the common section and form the downstream end portion, and the rotor casing may be provided with a plurality of nozzle structures, each set consisting of one branch section and the plurality of liquid supply holes connected to it.

[0015] According to the above configuration, liquid can be supplied simultaneously to a plurality of locations in the rotor chamber.

[0016] The plurality of nozzle structures may supply the liquid to different tooth spaces of the screw rotor.

[0017] According to the above configuration, the liquid can be supplied according to the stage of the compression process, and the cooling and sealing properties are improved.

[0018] The plurality of sets of nozzle structures may supply the liquid to the same tooth grooves of the screw rotor.

[0019] According to the above configuration, the liquid can be quickly spread throughout the entire tooth groove, improving cooling and sealing properties. [Effects of the Invention]

[0020] According to the present invention, the cooling and sealing properties of a liquid-cooled screw compressor can be improved. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic plan view of a screw compressor according to a first embodiment. [Figure 2] Cross-sectional view of II-II in Figure 1. [Figure 3] Cross-sectional view of FIG. 1 taken along line III-III. [Figure 4] FIG. 2 is a schematic diagram showing an example of a liquid circulation system provided in the screw compressor. [Figure 5] FIG. 10 is a schematic diagram showing another example of a liquid circulation system. [Figure 6] FIG. 2 is a partially enlarged view of FIG. 1, showing the liquid supply port as viewed from the rotor chamber. [Figure 7] 7 is a partially enlarged view of FIG. 3 and a cross-sectional view taken along line VII-VII in FIG. 6, showing one set of nozzle structures. [Figure 8] FIG. 10 is a view of a liquid supply port of a screw compressor according to a second embodiment, as viewed from a rotor chamber. [Figure 9] FIG. 10 is a cross-sectional view showing a set of nozzle structures of a screw compressor according to a third embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a set of nozzle structures of a screw compressor according to a fourth embodiment. [Figure 11] FIG. 11 is a view of a liquid supply port of a screw compressor according to a fifth embodiment, as viewed from a rotor chamber. [Figure 12] XII-XII cross section of Figure 11. [Figure 13] FIG. 10 is a cross-sectional view showing a set of nozzle structures of a screw compressor according to a sixth embodiment. [Figure 14] FIG. 13 is a cross-sectional view showing a modification of the sixth embodiment. [Figure 15] FIG. 13 is a cross-sectional view showing a set of nozzle structures of a screw compressor according to a seventh embodiment. [Figure 16] FIG. 13 is a cross-sectional view showing a set of nozzle structures of a screw compressor according to an eighth embodiment. [Figure 17] FIG. 13 is a schematic plan view of a screw compressor according to a ninth embodiment. [Figure 18] FIG. 20 is an axial cross-sectional view of a screw compressor according to a tenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or corresponding elements are designated by the same reference numerals throughout the drawings, and detailed descriptions thereof will be omitted.

[0023] (First embodiment) 1 to 3, a screw compressor 1 according to the first embodiment includes at least one screw rotor 2 having a plurality of tooth grooves, and a rotor casing 5 that forms a rotor chamber 6 that houses the screw rotor 2. The screw rotor 2 is composed of a male rotor 3 and a female rotor 4. The rotor chamber 6 includes a male rotor chamber 7 that houses the male rotor 3 and a female rotor chamber 8 that houses the female rotor 4, and the male rotor chamber 7 and the female rotor chamber 8 are spatially connected to each other.

[0024] The male rotor chamber 7 is defined by a cylindrical surface 5a and a pair of end faces 5c, 5d in the axial direction. The female rotor chamber 8 is defined by a cylindrical surface 5b adjacent to the cylindrical surface 5a and a pair of end faces 5c, 5d common to the male rotor chamber 7. The male rotor 3 is coaxial with the male rotor chamber 7, and the female rotor 4 is coaxial with the female rotor chamber 8.

[0025] The male rotor 3 comprises a male rotor shaft 3a and a plurality of helical teeth 3b provided on the outer periphery of the male rotor shaft 3a. Helical tooth spaces 3c are defined between adjacent tooth spaces 3b. The female rotor 4 comprises a female rotor shaft 4a parallel to the male rotor shaft 3a and a plurality of helical teeth 4b provided on the outer periphery of the female rotor shaft 4a. Helical tooth spaces 4c are defined between adjacent tooth spaces 4b.

[0026] The male rotor shaft 3a is supported by bearings 41 and 42 installed in the rotor casing 5 so as to be rotatable about its central axis A3. The female rotor shaft 4a is supported by bearings 43 and 44 installed in the rotor casing 5 so as to be rotatable about its central axis A4. The male rotor 3 and the female rotor 4 are meshed with each other with the teeth 3b inserted into the tooth grooves 4c. The male rotor shaft 3a is mechanically connected to a drive mechanism including a motor. When the drive mechanism is activated, the male rotor 3 is driven to rotate, and the female rotor 4 rotates synchronously with the male rotor 3. The female rotor 4 may also be driven to rotate by the drive mechanism.

[0027] The rotor casing 5 is provided with an inlet port 9 and a discharge port 10 which are spatially connected to the rotor chamber 6. When the screw rotor 2 rotates, a gas such as air is sucked into the rotor chamber 6 through the inlet port 9, is trapped in a compression space defined by the tooth portions 3b, tooth grooves 4c, and cylindrical surfaces 5a, 5b, is compressed while moving axially, and is discharged out of the rotor chamber 6 through the discharge port 10.

[0028] The screw compressor 1 is a liquid-cooled type. The rotor casing 5 is provided with a plurality of nozzle structures 20 for supplying a cooling liquid to the rotor chamber 6. Typically, the liquid is oil, and the screw compressor 1 is an oil-cooled type. The specific components of the oil are not particularly limited.

[0029] In this embodiment, for example, three sets of nozzle structures 20 are provided. However, the number of sets of nozzle structures 20 is not particularly limited as long as it is one or more. In this embodiment, for example, each of the multiple sets of nozzle structures 20 supplies liquid to a female rotor chamber 8 that houses at least one female rotor 4, which is a screw rotor 3. However, the nozzle structure 20 may supply liquid to a male rotor chamber 7 in addition to or instead of the female rotor chamber 8 (see the tenth embodiment). In this embodiment, for example, the multiple sets of nozzle structures 20 supply liquid to different tooth grooves 4c from each other. However, the multiple sets of nozzle structures 20 may supply liquid to the same tooth groove 4c from each other (see the ninth embodiment).

[0030] The liquid not only performs a cooling function, but also a lubricating function and a sealing function. The sealing function refers to the function of sealing the gas to be compressed within the compression space, and is achieved by filling the gap between the screw rotor 2 and the rotor casing 5 and the gap between the male rotor 3 and the female rotor 4 with liquid. It is believed that by spreading the liquid widely throughout the compression space, the cooling and sealing properties of the liquid-cooled screw compressor 1 are improved. Because the liquid is supplied to the compression space, the compressed air discharged from the discharge port 10 contains liquid.

[0031] Referring to FIG. 4, the screw compressor 1 is provided with a liquid circulation system 11 that recovers liquid from compressed air and supplies it to the compression space. The compressed air is introduced into a separator 13 via an air pipe 12A. The liquid is separated from the compressed air in the separator 13. The compressed air is sent from the separator 13 via an air pipe 12B to devices and equipment that require compressed air. The liquid is sent from the separator 13 via a liquid pipe 14 to a liquid supply path 16. The liquid supply path 16 is provided in the rotor casing 5 to supply liquid to the rotor chamber 6.

[0032] In the example shown in Fig. 4, the liquid is supplied from the separator 13 to the screw compressor 1 by utilizing a pressure difference. Alternatively, as shown in Fig. 5, the liquid circulation system 11 may include a pump 15 interposed in the liquid piping 14, and the liquid may be pumped to the screw compressor 1 by the pump 15.

[0033] 1 and 2, the liquid supply path 16 includes a common portion 17 that forms an upstream portion in the liquid flow direction, and multiple branch portions 18 that branch off from the common portion 17 and form a downstream end portion in the liquid flow direction. The common portion 17 is also referred to as a liquid supply line. The common portion 17 is formed, for example, by an elongated hole drilled in the rotor casing 5, is positioned on the outer periphery of the female rotor chamber 8, and extends linearly along the central axis A4 of the female rotor 4 (the central axis of the female rotor chamber 8). The multiple branch portions 18 are arranged at intervals along the extension direction of the common portion 17.

[0034] 3 and 7, each branch portion 18 extends radially from the branch point with the common portion 17 toward the central axis A4 of the female rotor 4. Hereinafter, the central axis of the branch portion 18 will be referred to as the "reference axis A18." The reference axis A18 extends in a direction perpendicular to the central axis A4.

[0035] Each nozzle structure 20 is composed of one branched portion 18 and a plurality of liquid supply holes 21 and 22 connected to this branched portion 18.

[0036] In this embodiment, as an example, both the branch portion 18 and the liquid supply holes 21, 22 are drilled in the rotor casing 5. However, the liquid supply holes 21, 22 may be formed in a nozzle member 30 that is separate from the rotor casing 5 (see the sixth to eighth embodiments).

[0037] In this embodiment, as an example, two liquid supply holes 21 and 22 are provided. However, the number of liquid supply holes in each nozzle structure 20 is not particularly limited as long as it is plural (see the second embodiment).

[0038] 6 and 7, the liquid supply hole 21 has a smaller cross-sectional area than the branch portion 18. The liquid supply hole 21 opens into the cylindrical surface 5b that defines the female rotor chamber 8 and is open to the female rotor chamber 8. The liquid supply hole 21 has a circular cross-section that is perpendicular to the central axis A21. The cross-sectional area of ​​the liquid supply hole 21 is constant along the central axis A21. The central axis A21 of the liquid supply hole 21 extends linearly. The same is true for the liquid supply hole 22. However, the central axes A21, A22 do not have to extend linearly (see the fourth embodiment).

[0039] The central axis A21 of the liquid supply hole 21 is inclined with respect to the reference axis A18. The central axis A21 becomes farther away from the reference axis A18 as it moves from the connection with the liquid supply path 16 (more specifically, the branch portion 18 that constitutes the same nozzle structure 20 as the liquid supply hole 21) toward the rotor chamber 6 (female rotor chamber 8). Due to this inclination, the liquid supply hole 21 has a circular shape in a cross section perpendicular to the axis, but opens in an elliptical shape when viewed radially from the female rotor chamber 8.

[0040] The same applies to the central axis A22 of the liquid supply hole 22. That is, in this embodiment, the central axes A21, A22 of the multiple liquid supply holes 21, 22 all extend at an incline with respect to the reference axis A18. However, some of the central axes may not be inclined with respect to the reference axis A18 (see the fifth embodiment).

[0041] In this embodiment, the liquid supply holes 21 and 22 are arranged symmetrically with respect to the reference axis A18. The inclination angle θ21 of the central axis A21 with respect to the reference axis A18 is equal to the inclination angle θ22 of the central axis A22 with respect to the reference axis A18. However, the liquid supply holes 21 and 22 may be asymmetric (see the third embodiment).

[0042] The central axes A21 and A22 extend so as not to intersect with each other on the downstream side in the liquid flow direction. In this embodiment, the central axes A21 and A22 extend so as to become farther apart from each other as they move downstream.

[0043] The two liquid supply holes 21, 22 are arranged opposite each other in the diameter direction of the reference axis A18 when viewed radially from the female rotor chamber 8. In other words, the two liquid supply holes 21, 22 are arranged 180 degrees apart in the circumferential direction of the reference axis A18.

[0044] According to the above configuration, liquid flows from separator 13 through liquid piping 14 into liquid supply path 16. The liquid flows through common section 17 and is divided into multiple nozzle structures 20. In each nozzle structure 20, the liquid flows along branch section 18 toward the center of female rotor chamber 8 and is divided into multiple liquid supply holes 21, 22 from the downstream end of branch section 18. A portion of the liquid flows through liquid supply hole 21 and is sprayed into female rotor chamber 8 through an opening on cylindrical surface 5b. A portion of the liquid flows through liquid supply hole 22 and is sprayed into female rotor chamber 8 through an opening on cylindrical surface 5b. The multiple liquid supply holes 21, 22 constituting one and the same nozzle structure supply liquid to the same tooth groove 4c among the multiple tooth grooves 4c of female rotor 4.

[0045] If the central axis of the nozzle structure 20 as a whole were to extend in a direction perpendicular to the central axis A4 of the female rotor 4, the liquid would be supplied to the tooth grooves 4c in a localized, dotted manner in a plan view, making it difficult to spread the liquid throughout the entire tooth grooves 4c.

[0046] In contrast, in this embodiment, the central axes A21, A22 of the liquid supply holes 21, 22 extend at an angle relative to the reference axis A18 so as to move away from the reference axis A18. Therefore, the liquid injection direction has components perpendicular to the axis, axial, or both. The liquid is injected linearly in a plan view and spreads widely throughout the tooth grooves 4c. Furthermore, the central axes A21, A22 of the liquid supply holes 21, 22 extend so as not to intersect with each other downstream. Therefore, liquid injected into the female rotor chamber 8 from the multiple liquid supply holes 21, 22 spreads widely throughout the tooth grooves 4c without intersecting or colliding with each other.

[0047] This shortens the time it takes for the gaps defining the compression space to be filled with liquid, reducing gas leakage from the compression space. Furthermore, the time it takes for the liquid to reach the entire tooth groove 4c can be shortened, lengthening the time for heat exchange between the heated compressed air and the liquid. This improves cooling performance and reduces the power required to compress the gas to the required pressure. This improves the cooling performance and sealing performance of the liquid-cooled screw compressor 1, contributing to energy savings.

[0048] Both central axes A21 and A22 extend at an angle relative to the reference axis A18, which allows the liquid to more widely distribute throughout the compression space. The central axes A21 and A22 extend farther apart as they extend downstream, which allows the liquid to more widely distribute throughout the compression space.

[0049] The rotor casing 5 is provided with a plurality of nozzle structures 20, each consisting of one branch portion 18 and a plurality of liquid supply holes 21, 22 connected thereto. This allows liquid to be supplied simultaneously to a plurality of locations in the rotor chamber 6. Furthermore, the plurality of nozzle structures 20 supplies liquid to different tooth grooves 4c. This allows liquid to be supplied according to the stage of the compression process, further improving the cooling and sealing properties of the liquid-cooled screw compressor 1.

[0050] (Second embodiment) Fig. 8 is a view of a screw compressor according to a second embodiment, which corresponds to Fig. 6. As shown in Fig. 8, three liquid supply holes 21 to 23 may be provided for one set of nozzle structure 20.

[0051] The three liquid supply holes 21-23 are arranged at equal intervals in the circumferential direction of the reference axis A18. If the nozzle structure 20 is cut along line AA in FIG. 8, a cross-sectional view similar to that of FIG. 7 can be obtained. In this embodiment as well, the central axes A21-A23 of the liquid supply holes 21-23 all extend at an angle relative to the reference axis A18. The central axes A21-A23 extend so as not to intersect with each other downstream in the liquid flow direction. The central axes A21-A23 extend so as to become farther apart from each other as they extend downstream. With this configuration as well, the same effects as those of the above embodiment can be obtained.

[0052] (Third embodiment) Fig. 9 is a view of a screw compressor according to a third embodiment, corresponding to Fig. 7. As shown in Fig. 9, the inclination angle θ21 of the central axis A21 of the liquid supply hole 21 and the inclination angle θ22 of the central axis A22 of the liquid supply hole 22 may be different.

[0053] By adjusting the inclination angles θ21 and θ22, the injection direction of the liquid from each liquid supply hole 21 and 22 can be intentionally adjusted. By adjusting the injection direction, the liquid can be efficiently distributed throughout the entire tooth groove 4c. This embodiment can also be applied to a screw compressor having three or more sets of nozzle structures 20.

[0054] (Fourth embodiment) Fig. 10 is a view corresponding to Fig. 7 of a screw compressor according to a fifth embodiment. As shown in Fig. 10, the central axis A21 of the liquid supply hole 21 does not necessarily extend in a straight line. In this embodiment, the central axis A21 extends in a polygonal line, and the central axes A21 and A22 extend so as not to intersect with each other downstream. Even with this configuration, the same effects as those of the above-described embodiment can be obtained.

[0055] Although not shown in detail, the central axis A21 may extend in a curved line. Two or more central axes A21, A22 may extend in a broken line or a curved line.

[0056] (Fifth embodiment) Fig. 11 is a view of a screw compressor according to a fifth embodiment, which corresponds to Fig. 6, and Fig. 12 is a view thereof, which corresponds to Fig. 7. Referring to Figs. 11 and 12, in this embodiment, one nozzle structure 20 includes, as a plurality of liquid supply holes, three inclined holes 21a, 22a, 23a and three parallel holes 24 to 26. The three inclined holes 21a, 22a, 23a are similar to the liquid supply holes 21 to 23 according to the second embodiment.

[0057] The central axis A24 of the parallel hole 24 extends parallel to the reference axis A18 at a position spaced apart from the reference axis A18 in a direction perpendicular to the reference axis A18. The central axis A25 of the parallel hole 25 and the central axis A26 of the parallel hole 26 are similarly arranged. The three parallel holes 24-26 are disposed at equal intervals in the circumferential direction of the reference axis A18. Each of the parallel holes 24-26 is disposed between two of the three inclined holes 21a, 22a, 23a that are adjacent in the circumferential direction. When viewed from the female rotor chamber 8, the openings of the inclined holes 21a, 22a, 23a and the parallel holes 24-26 are alternately arranged in the circumferential direction of the reference axis A18.

[0058] The cross-sectional areas of the three inclined holes 21a, 22a, and 23a are equal to one another, and the cross-sectional areas of the three parallel holes 24 to 26 are equal to one another. The cross-sectional area of ​​each of the parallel holes 24 to 26 is smaller than the cross-sectional area of ​​each of the inclined holes 21a, 22a, and 23a. Therefore, the ejection speed of the liquid from the parallel holes 24 to 26 is faster than the ejection speed of the liquid from the inclined holes 21a, 22a, and 23a.

[0059] In this embodiment, the liquid can be widely distributed throughout the compression space in the same manner as in the above embodiment. Note that the number and arrangement of the inclined holes 21a, 22a, 23a and the parallel holes 24 to 26 are not particularly limited and can be changed as appropriate.

[0060] (Sixth embodiment) Fig. 13 is a view of a screw compressor according to a sixth embodiment, which corresponds to Fig. 7. The nozzle structure 20 according to this embodiment differs from the nozzle structure 20 according to the first embodiment in that the liquid supply holes 21, 22 are not directly drilled in the rotor casing 5, but are formed in a nozzle member 30 separate from the rotor casing 5.

[0061] The rotor casing 5 has a mounting hole 5e that opens into the rotor chamber 6 and communicates with the branch portion 18. The mounting hole 5e has a circular cross section and a constant diameter in its axial direction. The mounting hole 5e extends linearly in a direction perpendicular to the central axis A4 of the female rotor shaft 4a and is coaxial with the branch portion 18. In this embodiment, the branch portion 18 is drilled in the rotor casing 5. The mounting hole 5e has a smaller diameter than the branch portion 18.

[0062] The nozzle member 30 is cylindrical and is attached to the mounting hole 5e. The attachment method is not particularly limited and may be press-fitting or screw-fitting. The axial length of the nozzle member 30 is shorter than the depth of the mounting hole 5e. Therefore, in this embodiment, one end face of the nozzle member 30 is positioned flush with the step surface between the mounting hole 5e and the branching portion 18. The other end face of the nozzle member 30 is positioned inside the mounting hole 5e, which is upstream of the inner circumferential surface of the rotor chamber 6 in the liquid flow direction. When the nozzle member 30 is attached to the mounting hole 5e, one end opening of the liquid supply hole 21 opens to the branching portion 18, and the other end opening of the liquid supply hole 21 opens to the rotor chamber 6. The same applies to both openings of the liquid supply hole 22.

[0063] The liquid supply holes 21, 22 extend at an angle relative to the reference axis A18 (the central axis of the branch portion 18). While holes that extend perpendicular to the axis, such as the mounting hole 5e, can be formed, it is difficult or complicated to directly form the inclined liquid supply holes 21, 22 in the rotor casing 5 by drilling. By forming the liquid supply holes 21, 22 in the separate nozzle member 30, the inclined liquid supply holes 21, 22 can be easily provided in the rotor casing 5.

[0064] Furthermore, by preparing multiple types of nozzle members 30 with different diameters according to the product specifications, the amount of liquid supplied can be easily adjusted. In other words, the rotor casing 5 can be standardized regardless of the product specifications. This improves production efficiency and ensures a high level of quality stability.

[0065] 14 shows a modified example of the sixth embodiment. In this modified example, the plurality of liquid supply holes in one nozzle structure 20 includes one or more inclined holes 21a and one or more parallel holes 24, as in the fifth embodiment. In this case, forming the liquid supply holes requires multiple fine drilling processes. In such a case, by drilling the nozzle member 30, which is a separate body, rather than the rotor casing 5, the production efficiency of the nozzle structure 20 is greatly improved.

[0066] Seventh embodiment Figure 15 is a view of a screw compressor according to a seventh embodiment, corresponding to Figure 7. The nozzle structure 20 according to this embodiment differs from the nozzle structure 20 according to the sixth embodiment in that the nozzle member 30 is chamfered. The downstream ends of the liquid supply holes 21 and 22 are open.

[0067] The chamfering provides a tapered surface 30a on the nozzle member 30 between the outer circumferential surface and the tip surface facing the rotor chamber 6. The liquid supply holes 21 and 22 open on the tapered surface 30a, and the central axes A21 and A22 extend perpendicular to the tapered surface 30a. When the nozzle member 30 is attached to the mounting hole 5e, the central axis of the nozzle member 30 becomes coaxial with the reference axis A18.

[0068] The liquid supply holes 21, 22 are formed by drilling from the tapered surface 30a of the nozzle member 30. By applying a drill perpendicularly to the tapered surface 30a, the liquid supply holes 21, 22 can be formed at an angle with respect to the reference axis A18. The liquid supply holes 21, 22 can be easily formed, improving the production efficiency of the nozzle structure 20.

[0069] (Eighth embodiment) Figure 16 is a view of a screw compressor according to an eighth embodiment, corresponding to Figure 6. The nozzle structure 20 according to this embodiment differs from the nozzle structure 20 according to the first embodiment in that the branch portion 18 is not directly drilled in the rotor casing 5, but is formed in a nozzle member 30 separate from the rotor casing 5.

[0070] In this embodiment, the mounting hole 5e opens to the common portion 17 (see FIG. 3) and the rotor chamber 6. The mounting hole 5e includes a large diameter portion 5f that communicates with the common portion 17 and a small diameter portion 5g that is smaller in diameter than the large diameter portion 5f and communicates with the rotor chamber 6. The large diameter portion 5f and the small diameter portion 5g are coaxial and continuous in the axial direction. An internal thread is formed on the inner peripheral surface of the large diameter portion 5f.

[0071] On the other hand, the nozzle member 30 is a stepped cylinder having a large diameter portion 31 and a small diameter portion 32 that is smaller in diameter than the large diameter portion 31. The large diameter portion 31 and the small diameter portion 32 are coaxial and continuous in the axial direction. A male thread is formed on the outer circumferential surface of the large diameter portion 31. When the nozzle member 30 is attached to the mounting hole 5e, the small diameter portion 32 is inserted into the small diameter portion 5g via the large diameter portion 5f, and the large diameter portion 31 is screwed onto the large diameter portion 5f.

[0072] The nozzle member 30 is formed with a branching portion 18 and an inclined hole and a parallel hole as liquid supply holes. The branching portion 18 is formed by non-through boring from the end face of the large diameter portion to the inside of the small diameter portion. The liquid supply hole is formed by boring from the end face of the small diameter portion to the tip of the branching portion 18, thereby communicating with the branching portion 18.

[0073] By forming the branch portion 18 on the nozzle member 30, which is separate from the rotor casing 5, the angle restriction on the liquid supply hole 21 is relaxed. If the branch portion 18 is not drilled, the axial length of the nozzle 30 needs to be determined so that the central axis A21 of the liquid supply hole 21 and the central axis A24 of the liquid supply hole 24 do not intersect. In this case, in order to provide a male thread on the large diameter portion 31, the axial length needs to be equal to or greater than the effective thread length, and if there is no branch portion 18, the angle at which the liquid supply hole 21 is provided is restricted so that the central axis A21 of the liquid supply hole 21 and the central axis A24 of the liquid supply hole 24 do not intersect.

[0074] (Ninth embodiment) 17 is a view of the ninth embodiment, corresponding to FIG. 1. In this embodiment, five sets of nozzle structures 20 (20A, 20B, 20C) are provided. Three sets of nozzle structures 20A among them supply liquid to the same tooth grooves 4c. This allows liquid to be supplied to a wider area in the compression space defined by the tooth grooves 4c.

[0075] Some of the multiple sets of nozzle structures (the above-mentioned three sets of nozzle structures 20A) may constitute a group that supplies liquid to the same tooth grooves 4c, while the nozzle structure 20A that constitutes the group and the other nozzle structures 20B and 20C may supply liquid to different tooth grooves 4c. In this case, the multiple sets of nozzle structures 20 are arranged in a dispersed manner in the axial and circumferential directions of the rotor casing 5. The extending direction and arrangement of the common portion 17 are changed as appropriate so that liquid can be supplied to each of the dispersed multiple sets of nozzle structures 20.

[0076] (Tenth embodiment) 18 is a view of a screw compressor according to a tenth embodiment, corresponding to FIG. 3. In this embodiment, liquid supply holes 21 and 22 open to the cylindrical surface 5a, and liquid is supplied to the male rotor chamber 7 by a nozzle structure 20. As a result, as in the above-described embodiment, the liquid can be distributed throughout the entire tooth groove 3c, improving cooling and sealing properties.

[0077] Although the embodiments have been described above, the above configurations can be modified as appropriate within the scope of the present invention.

[0078] The present disclosure may include the following aspects. (Aspect 1) At least one screw rotor having a plurality of tooth spaces; a rotor casing having a rotor chamber in which the screw rotor is housed; a liquid supply passage provided in the rotor casing for supplying liquid to the rotor chamber; a plurality of liquid supply holes each having a cross-sectional area smaller than that of the liquid supply passage, connected to a downstream end of the liquid supply passage in a liquid flow direction, and opening into the rotor chamber; Equipped with When a central axis of the liquid supply passage at the downstream end is taken as a reference axis, the central axis of at least one of the liquid supply holes extends at an angle to the reference axis so as to become farther away from the reference axis from the connection portion with the liquid supply passage toward the rotor chamber, and the central axes of the plurality of liquid supply holes extend so as not to intersect with each other downstream in the liquid flow direction. Liquid-cooled screw compressor. (Aspect 2) The central axes of the plurality of liquid supply holes all extend at an angle with respect to the reference axis line. 2. The liquid-cooled screw compressor according to claim 1. (Aspect 3) a central axis of at least one of the liquid supply holes extends parallel to the reference axis at a position spaced apart from the reference axis in a direction perpendicular to the reference axis; 2. The liquid-cooled screw compressor according to claim 1. (Aspect 4) the rotor casing has a mounting hole that opens into the rotor chamber and communicates with the liquid supply passage, the liquid supply hole is formed in a nozzle member that is separate from the rotor casing and is attached to the mounting hole; A liquid-cooled screw compressor according to any one of aspects 1 to 3. (Aspect 5) the liquid supply path includes a common portion that forms an upstream portion in the liquid flow direction, and a plurality of branch portions that branch off from the common portion and form the downstream end portion, The rotor casing is provided with a plurality of nozzle structures, each of which is formed by one of the branch portions and the plurality of liquid supply holes connected thereto. A liquid-cooled screw compressor according to any one of aspects 1 to 4. (Aspect 6) the plurality of nozzle structures supply the liquid to different tooth spaces of the screw rotor; 6. The liquid-cooled screw compressor according to claim 5. (Aspect 7) the plurality of nozzle structures supply the liquid to the same tooth groove of the screw rotor; 6. The liquid-cooled screw compressor according to claim 5. [Explanation of symbols]

[0079] 1. Screw compressor 2 screw rotor 3 Male Rotors 3a Male rotor shaft 3b Teeth 3c Tooth groove 4 female rotors 4a Female rotor shaft 4b Teeth 4c Tooth groove 5 Rotor casing 5a,5b Cylindrical surface 5c,5d end face 5e mounting hole 5f Large diameter section 5g small diameter part 6 Rotor Room 7 Male rotor chamber 8 Female rotor chamber 9 Intake port 10 outlet 11 Fluid circulation system 12A, 12B air piping 13 Separator 14 Liquid piping 15 Pump 16 Liquid supply path 17 Common area 18 Branch 20 Nozzle structure 21~23 Liquid supply hole 21a,22a,23a Slanted hole 24~26 parallel holes 30 Nozzle member 31 Large diameter section 32 Small diameter section A3,A4,A21~A26 center axis A18 Reference axis θ21,θ22 Inclination angle

Claims

1. At least one screw rotor having a plurality of tooth spaces; a rotor casing having a rotor chamber in which the screw rotor is housed; a liquid supply passage provided in the rotor casing for supplying liquid to the rotor chamber; a plurality of liquid supply holes each having a cross-sectional area smaller than that of the liquid supply passage, connected to a downstream end of the liquid supply passage in a liquid flow direction, and opening into the rotor chamber; Equipped with When a central axis of the liquid supply passage at the downstream end is taken as a reference axis, the central axis of at least one of the liquid supply holes extends at an angle to the reference axis so as to become farther away from the reference axis from the connection portion with the liquid supply passage toward the rotor chamber, and the central axes of the plurality of liquid supply holes extend so as not to intersect with each other downstream in the liquid flow direction. Liquid-cooled screw compressor.

2. The central axes of the plurality of liquid supply holes all extend at an angle with respect to the reference axis line. The liquid-cooled screw compressor according to claim 1.

3. a central axis of at least one of the liquid supply holes extends parallel to the reference axis at a position spaced apart from the reference axis in a direction perpendicular to the reference axis; The liquid-cooled screw compressor according to claim 1.

4. the rotor casing has a mounting hole that opens into the rotor chamber and communicates with the liquid supply passage, the liquid supply hole is formed in a nozzle member that is separate from the rotor casing and is attached to the mounting hole; The liquid-cooled screw compressor according to any one of claims 1 to 3.

5. the liquid supply path includes a common portion that forms an upstream portion in the liquid flow direction, and a plurality of branch portions that branch off from the common portion and form the downstream end portion, the rotor casing is provided with a plurality of nozzle structures, each of which is formed by one of the branch portions and the plurality of liquid supply holes connected thereto; The liquid-cooled screw compressor according to any one of claims 1 to 3.

6. the plurality of nozzle structures supply the liquid to different tooth spaces of the screw rotor; The liquid-cooled screw compressor according to claim 5.

7. the plurality of nozzle structures supply the liquid to the same tooth groove of the screw rotor; The liquid-cooled screw compressor according to claim 5.

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