Liquid-feed screw compressor

Abstract

To provide a liquid supply type screw compressor which can form a swirl chamber in a wall part of a casing without forming an opening part on the outer face of the casing.SOLUTION: A screw compressor 1 comprises a casing 4 having a liquid supply mechanism 60 for supplying liquid to an accommodation chamber 40 which accommodates screw rotors 2, 3. The liquid supply mechanism 60 has an injection hole 62 opened at the accommodation chamber 40, a swirl chamber 63 located at an upstream side of the injection hole 62, and an introduction path 64 for introducing the liquid into the swirl chamber 63. The casing 4 includes first and second casing segments 51, 52 which are divided with a face or the like traversing the accommodation chamber 40 as a dividing plane P1. The swirl chamber 63 is constituted by a recess 522 which is opened at least at one joining face 521 of the first and second casing segments 51, 52. The introduction path 64 is constituted by a hole part 512 or the like which is opened at the other joining face 511 of the first and second casing segments 51, 52.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a liquid feed type screw compressor in which liquid is supplied from the outside to the inside of the compressor. [Background technology]

[0002] A screw compressor has a screw rotor with twisted teeth (lobes) and a casing that houses the screw rotor. The volume of the working chamber formed by the teeth of the screw rotor and the inner wall surface of the casing increases and decreases as the screw rotor rotates, thereby compressing gas. Some screw compressors are of the liquid feed type, in which a liquid such as oil or water is supplied to the working chamber inside the compressor. The liquid supplied to the compressor cools the compressed gas in the working chamber, seals the internal gap between the screw rotor and the casing, and lubricates the screw rotor.

[0003] As a liquid-feed screw compressor, for example, one that supplies atomized liquid to a working chamber has been proposed (see, for example, Patent Document 1). The screw compressor described in Patent Document 1 is configured to supply lubricating liquid from a lubricating liquid passage provided in a housing (casing) to a compression chamber (working chamber) in the housing via a lubricating liquid port. The lubricating liquid passage extends offset from the center line of the lubricating liquid port and is connected to the lubricating liquid port via an introduction passage, so that the lubricating liquid flows tangentially into the lubricating liquid port (swirl chamber). With this configuration, a swirling flow of lubricating liquid is generated in the lubricating liquid port (swirl chamber). The swirling flow of lubricating liquid generated in the lubricating liquid port (swirl chamber) is injected into the compression chamber through a discharge orifice, where it is converted into atomized droplets and dispersed within the working chamber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2019 / 0093659 Summary of the Invention [Problem to be solved by the invention]

[0005] In the screw compressor described in Patent Document 1, a lubricating liquid port serving as a swirl chamber is formed by drilling a wall portion of the housing from the outer surface side using a drill, mill, etc. Therefore, a plug is disposed at one end of the lubricating liquid port (opening on the outer surface side of the housing) to prevent leakage of lubricating liquid from the lubricating liquid port (swirl chamber) to the outside of the housing.

[0006] When a swirl chamber is formed using the method described in Patent Document 1, providing multiple swirl chambers results in multiple openings on the outer surface of the housing (casing). In this type of structure, a sealing member such as a plug is required for each of the multiple openings, increasing the number of parts and the processing time required to attach the sealing members to the openings. Furthermore, the presence of multiple openings on the outer surface of the housing (casing) corresponding to the multiple swirl chambers increases the possibility of liquid leakage outside the compressor and increases the number of inspection points required to check for defects in the sealing members (liquid leakage from the sealing members).

[0007] The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid feed screw compressor in which a swirl chamber can be formed within the wall of the casing without providing an opening on the outer surface of the casing. [Means for solving the problem]

[0008] The present application employs the configurations described in the claims as means for solving the above problems. For example, the present application includes a screw rotor rotatable around an axis, and a casing having an accommodation chamber therein for accommodating the screw rotor and having a liquid supply mechanism in a wall portion for supplying liquid from outside to the accommodation chamber, the liquid supply mechanism including an injection hole that opens into the accommodation chamber and extends along a center line, a swirl chamber that is located upstream of the injection hole and generates a swirling flow that swirls around an axis that extends in the same direction as the center line of the injection hole, and a swirl chamber that .... In front and an introduction passage for introducing the swirl chamber into the casing, the casing being divided at a dividing plane that crosses the accommodation chamber or a plane that includes the axis of the screw rotor, and including a first casing segment and a second casing segment that are joined to each other, and the swirl chamber is The other The introduction path is constituted by a recess provided in the joint surface of the casing segment so as to open at a position away from the wall surface of the storage chamber, and the introduction path is constituted by a hole provided so as to open into the joint surface of the other casing segment of the first casing segment and the second casing segment, or a hole provided so as to open into the recess toward the joint surface side of the casing segment having the recess. [Effects of the Invention]

[0009] According to the present invention, one of the first and second casing segments The other The recess opening onto the joint surface forms a swirl chamber, and the hole opening onto the other joint surface of the first and second casing segments or the hole opening into the recess forms an introduction passage, making it possible to process the swirl chamber and introduction passage from the joint surface of the casing segments, so that a swirl chamber can be formed within the wall of the casing without providing an opening on the outer surface side of the casing. Problems, configurations, and effects other than those described above will become clear from the following description of the embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a longitudinal sectional view showing a schematic configuration of a screw compressor according to a first embodiment of the present invention, and a system diagram showing an external path for supplying a liquid to the screw compressor. [Figure 2] 2 is a cross-sectional view of the screw compressor according to the first embodiment shown in FIG. 1, taken along the line II-II. [Figure 3] 3 is a cross-sectional view of the screw compressor according to the first embodiment shown in FIG. 1, taken along the arrows III-III. [Figure 4] 4 is a view showing the structure of a joining surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the first embodiment shown in FIG. 3 is viewed from the arrows IV-IV. FIG. [Figure 5] 4 is a view showing the structure of the joining surface on the other side of the joined casing segments when the liquid supply mechanism of the screw compressor according to the first embodiment shown in FIG. 3 is viewed from the direction of the arrows VV. FIG. [Figure 6] 3 is a cross-sectional view of a structure of a liquid supply mechanism of a screw compressor according to a modified example of the first embodiment, seen from the same direction as the arrows III-III shown in FIG. 1. FIG. [Figure 7] 7 is a view showing the structure of a joining surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the modified example of the first embodiment shown in FIG. 6 is viewed from the arrow VII-VII. FIG. [Figure 8] 8 is a diagram showing the structure of the joining surface on the other side of the joined casing segments when the liquid supply mechanism of the screw compressor according to the modified example of the first embodiment shown in FIG. 6 is viewed from the arrow VIII-VIII. [Figure 9] FIG. 4 is a vertical cross-sectional view showing a schematic configuration of a screw compressor according to a second embodiment of the present invention. [Figure 10] 10 is a cross-sectional view of the screw compressor according to the second embodiment shown in FIG. 9, viewed from the arrow XX. [Figure 11]11 is a view showing the structure of a joining surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the second embodiment shown in FIG. 10 is viewed from the arrows XI-XI. FIG. [Figure 12] 12 is a view showing the structure of the joining surface on the other side of the joined casing segments when the liquid supply mechanism of the screw compressor according to the second embodiment shown in FIG. 10 is viewed from the arrow XII-XII. FIG. [Figure 13] 10 is a cross-sectional view of a structure of a liquid supply mechanism of a screw compressor according to a first modified example of the second embodiment, as viewed in the same direction as the arrow XX shown in FIG. 9. [Figure 14] 14 is a view showing the structure of a joining surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the first modified example of the second embodiment shown in FIG. 13 is viewed from the arrow XIV-XIV direction. [Figure 15] 14 is a diagram showing the structure of the joining surface on the other side of the joined casing segments when the liquid supply mechanism of the screw compressor according to the first modified example of the second embodiment shown in FIG. 13 is viewed from the XV-XV arrow direction. [Figure 16] 10 is a cross-sectional view of a structure of a liquid supply mechanism of a screw compressor according to a second modified example of the second embodiment, as viewed in the same direction as the arrow XX shown in FIG. 9. [Figure 17] 17 is a diagram showing the structure of a joining surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the second modified example of the second embodiment shown in FIG. 16 is viewed from the arrow XVII-XVII. [Figure 18] 18 is a diagram showing the structure of the joining surface on the other side of the joined casing segments when the liquid supply mechanism of the screw compressor according to the second modified example of the second embodiment shown in FIG. 16 is viewed from the XVIII-XVIII arrow direction. [Figure 19] 10 is a cross-sectional view of a structure of a liquid supply mechanism of a screw compressor according to a third modified example of the second embodiment, as viewed in the same direction as the arrow XX shown in FIG. 9. [Figure 20] 20 is a diagram showing the structure of a joining surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the third modified example of the second embodiment shown in FIG. 19 is viewed from the arrows XX-XX. [Figure 21] 20 is a diagram showing the structure of the joining surface on the other side of the joined casing segments when the liquid supply mechanism of the screw compressor according to the third modified example of the second embodiment shown in FIG. 19 is viewed from the arrow XXI-XXI. [Figure 22] FIG. 10 is a vertical cross-sectional view showing a schematic configuration of a screw compressor according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of a screw compressor according to the present invention will be described with reference to the drawings. In this description, a twin-rotor screw compressor will be described as an example. However, the present invention can also be applied to a single-rotor screw compressor.

[0012] [First embodiment] The configuration of a screw compressor according to a first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a longitudinal sectional view showing the schematic configuration of a screw compressor according to a first embodiment of the present invention, and a system diagram showing an external path for supplying a liquid to the screw compressor. FIG. 2 is a sectional view of the screw compressor according to the first embodiment shown in FIG. 1, as seen from the direction of arrows II-II. In FIG. 1, the left side is the suction side of the screw compressor, and the right side is the discharge side. Here, the "suction side" refers to the side in the axial direction of the screw compressor that sucks in gas, and the "discharge side" refers to the side in the axial direction of the screw compressor that discharges gas. In FIG. 2, the thick arrow indicates the rotation direction of the screw rotor.

[0013] In FIG. 1, a liquid feed screw compressor 1 (hereinafter referred to as a screw compressor) is supplied with liquid (e.g., oil or water) from the outside into the compressor, and the supplied liquid is mixed into the compressed gas discharged. An external liquid feed system 100 is connected to the screw compressor 1. The external liquid feed system 100 is composed of, for example, a gas-liquid separator 101, a liquid cooler 102, an auxiliary device 103, and a pipeline 104 connecting these devices, and supplies liquid to the screw compressor 1. The gas-liquid separator 101 separates and recovers liquid contained in the compressed gas discharged from the screw compressor 1. The liquid cooler 102 cools the liquid separated by the gas-liquid separator 101. The auxiliary device 103 includes a filter that filters out impurities contained in the liquid separated by the gas-liquid separator 101 and a check valve that prevents the liquid from flowing back.

[0014] 1 and 2, the screw compressor 1 includes a male rotor 2 and a female rotor 3 as a pair of screw rotors that rotate in mesh with each other, and a casing 4 that rotatably houses both the male and female rotors 2 and 3. The male rotor 2 and the female rotor 3 are rotatable about rotation axes A1 and A2, respectively, and are arranged so that the rotation axes A1 and A2 are parallel to each other. The male rotor 2 is rotatably supported on both sides in its axial direction (left-right direction in FIG. 1) by a suction-side bearing 11 and a discharge-side bearing 12 (composed of two bearings in FIG. 1), and is connected to, for example, a motor 70 that serves as a rotational drive source. The female rotor 3 is rotatably supported on both sides in its axial direction by a suction-side bearing 13 and a discharge-side bearing 14 (see FIG. 22, described later).

[0015] The male rotor 2 is composed of a rotor tooth portion 21 having twisted teeth (lobes) 21a, and a suction-side shaft portion 22 and a discharge-side shaft portion 23 provided on both axial ends of the rotor tooth portion 21. The rotor tooth portion 21 has a suction-side end face 21b and a discharge-side end face 21c at one axial end (left end in FIG. 1) and the other axial end (right end in FIG. 1), respectively. Tooth grooves are formed between the multiple teeth 21a of the rotor tooth portion 21. The suction-side shaft portion 22, for example, penetrates the casing 4 and is configured to share a shaft portion with the rotary drive source 70. A shaft seal member 15 is disposed on the suction-side shaft portion 22 of the male rotor 2. The shaft seal member 15 is, for example, an oil seal or a mechanical seal.

[0016] As shown in Figure 2, the female rotor 3 is composed of a rotor tooth portion 31 having twisted teeth (lobes) 31a, and a suction-side shaft portion 32 (see Figure 22 described later) and a discharge-side shaft portion 33 provided on both axial ends of the rotor tooth portion 31. The rotor tooth portion 31 has a suction-side end face 31b and a discharge-side end face 31c (both see Figure 22 described later) at one axial end and the other axial end, respectively. Tooth spaces are formed between the teeth 31a of the rotor tooth portion 31.

[0017] 1 and 2, the casing 4 has an internal accommodating chamber 40 that accommodates the rotor teeth 21 of the male rotor 2 and the rotor teeth 31 of the female rotor 3 in a state where they mesh with each other. The accommodating chamber 40 is formed so that two cylindrical spaces partially overlap, and has a male side bore 40a that accommodates the rotor teeth 21 of the male rotor 2 and a female side bore 40b that accommodates the rotor teeth 31 of the female rotor 3. The wall surface (inner wall surface of the casing 4) forming the accommodating chamber 40 has an approximately cylindrical male side peripheral surface 41 covering the radial outside of the rotor tooth portion 21 of the male rotor 2, an approximately cylindrical female side peripheral surface 42 covering the radial outside of the rotor tooth portion 31 of the female rotor 3, an suction side inner wall surface 43 facing the suction side end faces 21b, 31b of the rotor tooth portions 21, 31 of both the male and female rotors 2, 3, and a discharge side inner wall surface 44 facing the discharge side end faces 21c, 31c of the rotor tooth portions 21, 31 of both the male and female rotors 2, 3.

[0018] The rotor teeth 21, 31 of the male and female rotors 2, 3 are arranged with gaps of several tens to several hundreds of μm relative to the inner wall surfaces (male side peripheral surface 41, female side peripheral surface 42, suction side inner wall surface 43, discharge side inner wall surface 44) of the casing 4. A plurality of working chambers C are formed by the rotor teeth 21, 31 of the male rotor 2 and female rotor 3 housed in the housing chamber 40 and the inner wall surface of the casing 4 surrounding them.

[0019] As shown in FIG. 1, one axial side (left side in FIG. 1) of the casing 4 is provided with a suction passage 46 that guides gas from the outside of the casing 4 to the working chamber C. The other axial side (right side in FIG. 1) of the casing 4 is provided with a discharge passage 47 that guides compressed gas from the working chamber C to the outside of the casing 4. The discharge passage 47 connects the working chamber C in the discharge stroke with the outside of the casing 4, and has a discharge port 48 that opens to the storage chamber 40. The discharge passage 47 is connected to an external liquid supply system 100.

[0020] As shown in FIG. 1, the casing 4 of this embodiment includes a first casing segment 51 (hereinafter referred to as the first segment 51) on the suction side (left side in FIG. 1) and a second casing segment 52 (hereinafter referred to as the second segment 52) ​​on the discharge side (right side in FIG. 1), which are divided along a dividing plane P1 that is perpendicular to the rotation axes A1, A2 of the male and female rotors 2, 3. The first segment 51 and the second segment 52 are joined to each other by bolting or the like. The first segment 51 has a first joint surface 511, which is a joint surface with the second segment 52, at the position of the dividing plane P1. The second segment 52 has a second joint surface 521, which is a joint surface with the first segment 51, at the position of the dividing plane P1. At the end of the first segment 51 opposite the first joint surface 511, the suction side bearing 11 on the male rotor 2 side and the suction side bearing 13 on the female rotor 3 side are arranged, and a suction side cover 53 is attached to cover the suction side bearings 11, 13. At the end of the second segment 52 opposite the second joint surface 521, the discharge side bearing 12 on the male rotor 2 side and the discharge side bearing 14 on the female rotor 3 side are arranged, and a discharge side cover 54 is attached to cover the discharge side bearings 12, 14.

[0021] A liquid (e.g., oil or water) is supplied to the working chamber C for the purposes of cooling the compressed gas in the working chamber C, lubricating the male rotor 2 and female rotor 3, and sealing gaps between the male and female rotors 2, 3 and the wall surface of the accommodation chamber 40 (the inner wall surface of the casing 4) and gaps at the meshing portions of the male rotor 2 and female rotor 3. The casing 4 has a liquid supply mechanism 60 in its wall for supplying liquid supplied from outside the screw compressor 1 (from an external liquid supply system 100) to the working chamber C.

[0022] 1 and 2, the liquid supply mechanism 60 includes a liquid supply passage 61 to which liquid is supplied from an external liquid supply system 100 (external), a plurality of injection holes 62 opening into the housing chamber 40, a swirl chamber 63 located upstream of each injection hole 62, and an introduction path 64 for introducing the liquid supplied to the liquid supply passage 61 into the swirl chamber 63. The liquid supply passage 61 has an opening provided on the outer surface of the casing 4 and an inlet portion connected to a pipe 104 of the external liquid supply system 100. The plurality of injection holes 62 are configured to open in a region of the male side bore 40a (male side circumferential surface 41) and the female side bore 40b (female side circumferential surface 42) where the working chamber C is undergoing a compression stroke, for example, as shown in FIG. 2, and are configured to inject liquid toward the working chamber C. The swirl chamber 63 is configured to generate a swirling flow of liquid introduced from the introduction passage 64, swirling around a swirl axis extending in the same direction as the extension direction of the injection hole, and supplies the swirling flow of liquid to the injection hole 62. The introduction passage 64 is a flow path connected to the downstream side of the liquid supply passage 61, and is configured to introduce the liquid along the circumferential direction of the swirl chamber 63.

[0023] In this embodiment, a first joint surface 511 of the first segment 51 and a second joint surface 521 of the second segment 52 in the casing 4 are joined together to form a swirling chamber 63, and an introduction passage 64 is connected to the swirling chamber 63. The structure of the liquid supply mechanism 60 will be described in detail later.

[0024] In the screw compressor 1 configured as described above, the rotary drive source 70 shown in Fig. 1 drives the male rotor 2, which in turn drives the female rotor 3 shown in Fig. 2 to rotate. As a result, the working chamber C shown in Fig. 1 moves in the axial direction as the male and female rotors 2, 3 rotate. At this time, the working chamber C increases its volume to suck in gas through the suction passage 46 of the casing 4, and compresses the gas to a predetermined pressure by reducing its volume. When the working chamber C communicates with the discharge port 48, the compressed gas in the working chamber C passes through the discharge passage 47 via the discharge port 48 and is discharged to the gas-liquid separator 101 of the external liquid supply system 100.

[0025] In the screw compressor 1, liquid is supplied to the working chamber C from the liquid supply mechanism 60. For this reason, liquid is mixed in the compressed gas discharged from the screw compressor 1. The liquid contained in the compressed gas is separated by the gas-liquid separator 101. The compressed gas from which the liquid has been removed by the gas-liquid separator 101 is supplied to an external device as needed. Meanwhile, the liquid separated from the compressed gas by the gas-liquid separator 101 is cooled by a liquid cooler 102 of the external liquid supply system 100, and then supplied again to the liquid supply mechanism 60 in the casing 4 via an auxiliary device 103. The supply of liquid to the screw compressor 1 by the external liquid supply system 100 can be performed using the pressure of the compressed gas flowing into the gas-liquid separator 101 as a driving source, without using a power source such as a pump.

[0026] Liquid supplied to the liquid supply mechanism 60 from the external liquid supply system 100 flows from the liquid supply passage 61 through the introduction passage 64 into the swirling chamber 63. The swirling flow of liquid generated in the swirling chamber 63 is sprayed from the injection hole 62 toward the working chamber C in the accommodation chamber 40. The liquid sprayed from the outlet of the injection hole 62 forms an umbrella-shaped liquid film due to the centrifugal force of the swirling flow, and the tip of the liquid film breaks into a liquid filament. The liquid filament then breaks into multiple droplets, generating fine liquid droplets. When the atomized liquid is dispersed in the working chamber C, the heat transfer area between the atomized liquid and the compressed gas in the working chamber C increases. Furthermore, because the overall surface area of ​​the atomized liquid increases, the heat exchange area between the atomized liquid and the compressed gas in the working chamber C increases accordingly. This promotes cooling of the compressed gas in the working chamber C, thereby reducing the driving power of the screw compressor 1.

[0027] Next, the structure of a liquid supply mechanism of a screw compressor according to a first embodiment will be described with reference to Figures 1 to 5. Figure 3 is a cross-sectional view of the screw compressor according to the first embodiment shown in Figure 1, as viewed from the arrows III-III. Figure 4 is a diagram showing the structure of the joint surfaces on one side (second segment) of the casing segment when the liquid supply mechanism of the screw compressor according to the first embodiment shown in Figure 3 is viewed from the arrows IV-IV. Figure 5 is a diagram showing the structure of the joint surfaces on the other side (first segment) of the casing segment when the liquid supply mechanism of the screw compressor according to the first embodiment shown in Figure 3 is viewed from the arrows VV.

[0028] As shown in FIGS. 3 and 4, the injection hole 62 of the liquid supply mechanism 60 is configured to extend along a center line 621 and open into the storage chamber 40, and is, for example, a circular hole. In FIG. 3, the injection hole 62 that does not appear in the cross section is shown projected onto the cross section by a two-dot chain line. In FIG. 4, the injection hole 62 that does not appear in the second joint surface 521 of the second segment 52 is shown by a dashed line. The injection hole 62 has an injection port 622 at one end in the extension direction that opens into the storage chamber 40 of the casing 4 (the male side circumferential surface 41 or the female side circumferential surface 42 as the inner wall surface of the casing 4), and has a connection port 623 at the other end in the extension direction that opens into the swirl chamber 63. The cross-sectional shape of the injection hole 62 is arbitrary as long as it can maintain the swirling flow introduced from the swirl chamber 63.

[0029] The swirl chamber 63 generates a swirling flow that swirls around an axis extending in approximately the same direction as the center line 621 of the injection hole 62. Specifically, as shown in FIGS. 3 and 4 , the swirl chamber 63 has a substantially rectangular cross section perpendicular to the center line 621 of the injection hole 62, and is formed as a substantially rectangular parallelepiped space extending in approximately the same direction as the center line 621 of the injection hole 62. The swirl chamber 63 is formed to be sufficiently larger than the diameter of the injection hole 62. The wall surfaces that form the swirl chamber 63 include a first bottom surface 631 and a second bottom surface 632 that face each other and are aligned in the extension direction of the injection hole 62, and a peripheral wall 633 that connects the periphery of the first bottom surface 631 and the periphery of the second bottom surface 632. A connection port 623 of the injection hole 62 opens into the first bottom surface 631 of the first bottom surface 631 and the second bottom surface 632, which is closer to the accommodation chamber 40. Of the four corners of the swirl chamber 63, three corners excluding the corner where the introduction passage 64 is connected are formed as curved surfaces 633a. The curved surfaces 633a at the corners of the peripheral wall 633 of the swirl chamber 63 are intended not to obstruct the swirling flow. In Fig. 4, the portion of the peripheral wall 633 of the swirl chamber 63 that does not appear on the second joint surface 521 of the second segment 52 is indicated by a dashed line.

[0030] 3 to 5, the introduction path 64 is configured to extend along a center line 641 and be connected to the swirl chamber 63, and is, for example, a round hole. The introduction path 64 is connected to the swirl chamber 63 so that the center line 641 is shifted relative to the center line 621 of the injection hole 62 without intersecting with it, and is configured so that the liquid is introduced along the circumferential direction of the swirl chamber 63. The introduction path 64 is connected so that the introduction port 642 opens at a corner position of the peripheral wall 633 of the swirl chamber 63, for example.

[0031] As described above, in this embodiment, the first joint surface 511 of the first segment 51 in the casing 4 and the second joint surface 521 of the second segment 52 are joined to form a swirling chamber 63, and an introduction passage 64 is connected to the swirling chamber 63.

[0032] Specifically, as shown in FIGS. 3 and 4 , a recess 522 functioning as the swirl chamber 63 is provided in the second joint surface 521 of the second segment 52. The recess 522 opens to the second joint surface 521 at a position away from the wall surface (male-side circumferential surface 41 or female-side circumferential surface 42) of the accommodation chamber 40. The second segment 52 is also provided with a communication hole 523 functioning as the injection hole 62. The communication hole 523 connects the recess 522 of the second segment 52 with the accommodation chamber 40, and is provided at a position away from the second joint surface 521. Of the side walls of the recess 522, the side wall where the communication hole 523 opens and the opposite side wall form the first bottom surface 631 and the second bottom surface 632 of the swirl chamber 63. The remaining side walls and bottom of the recess 522 form part of the circumferential wall 633 of the swirl chamber 63. In FIG. 4, the position corresponding to the introduction path 64 (hole 512) appearing in the first joint surface 511 of the first segment 51 opposite the second joint surface 521 of the second segment 52 is indicated by a two-dot chain line.

[0033] As shown in FIGS. 3 and 5 , the first segment 51 is provided with a hole 512 that functions as the introduction path 64. The hole 512 (inlet 642 of the introduction path 64) opens in the first joint surface 511 of the first segment 51. The opening of the hole 512 in the first joint surface 511 of the first segment 51 is formed at a position that overlaps with the opening of the recess 522 in the second joint surface 521 of the second segment 52, as shown in FIG. 4 . That is, the hole 512 opens at a position on the first joint surface 511 of the first segment 51 that connects to the recess 522 of the second segment 52. The hole 512 (introduction path 64) of the first segment 51 is formed so that, for example, its projection area in the normal direction onto the first joint surface 511 of the first segment 51 does not overlap with the communication hole 523 (injection hole 62) and is connected to the recess 522 (swirl chamber 63) of the second segment 52. In FIG. 5, the position corresponding to the opening of the recess 522 appearing on the second joint surface 521 of the second segment 52 opposite the first joint surface 511 of the first segment 51 is indicated by a two-dot chain line.

[0034] In this embodiment, the recess 522 of the second segment 52 can be formed by machining from the second joint surface 521 of the second segment 52. The communication hole 523 (injection hole 62) of the second segment 52 can be formed by machining from the wall surface (male-side circumferential surface 41 or female-side circumferential surface 42) of the accommodation chamber 40 of the second segment 52. Similarly, the hole 512 (introduction passage 64) of the first segment 51 can be formed by machining from the first joint surface 511 of the first segment 51.

[0035] When the first joint surface 511 of the first segment 51 and the second joint surface 521 of the second segment 52 are joined, the opening of the hole 512 in the first joint surface 511 of the first segment 51 (the inlet 642 of the introduction path 64) is connected to the opening of the recess 522 in the second joint surface 521 of the second segment 52, and the opening of the recess 522 in the second joint surface 521 of the second segment 52 is blocked by the first joint surface 511 of the first segment 51. This forms a swirl chamber 63 to which the introduction path 64 is connected so as to be offset from the connection position with the injection hole 62. In this configuration, as shown in FIG. 5 , a portion of the first joint surface 511 of the first segment 51 becomes a portion of the peripheral wall 633 of the swirl chamber 63.

[0036] In this manner, in the present embodiment, the swirl chamber 63 is formed by utilizing the joint surfaces of the casing 4 that were separated in order to process the accommodation chamber 40, and it is therefore possible to form the swirl chamber 63 without drilling holes from the outer surface side of the casing 4. In other words, the structure is such that the swirl chamber 63 is formed without providing an opening on the outer surface side of the casing 4 that requires a sealing member.

[0037] In the first embodiment, an example of a configuration has been shown in which the communication holes 523 and recesses 522 that function as the injection holes 62 and swirl chamber 63 of the liquid supply mechanism 60 are provided in the second segment 52, and the hole 512 that functions as the introduction path 64 of the liquid supply mechanism 60 is provided in the first segment 51. However, a configuration is also possible in which the communication holes and recesses that function as the injection holes 62 and swirl chamber 63 of the liquid supply mechanism 60 are provided in the first segment 51, and the hole that functions as the introduction path 64 of the liquid supply mechanism 60 is provided in the second segment 52.

[0038] [Modification of the first embodiment] Next, a screw compressor according to a modified example of the first embodiment will be described with reference to Figures 6 to 8. In Figures 6 to 8, the same reference numerals as those in Figures 1 to 5 denote similar parts, and detailed description thereof will be omitted. Figure 6 is a cross-sectional view showing the structure of a liquid supply mechanism of a screw compressor according to a modified example of the first embodiment, as seen from the same direction as the arrows III-III shown in Figure 1. Figure 7 is a diagram showing the structure of the joint surfaces on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the modified example of the first embodiment shown in Figure 6 is seen from the arrows VII-VII. Figure 8 is a diagram showing the structure of the joint surfaces on the other side of joined casing segments when the liquid supply mechanism of the screw compressor according to the modified example of the first embodiment shown in Figure 6 is seen from the arrows VIII-VIII.

[0039] The liquid supply mechanism 60A of the modified example of the first embodiment shown in Figure 6 differs from the liquid supply mechanism 60 of the first embodiment (see Figure 3) in that the recess 513 functioning as the swirling chamber 63A and the communication hole 514 functioning as the injection hole 62A are formed on the first segment 51 side rather than the second segment 52 side, and the hole portion 512A functioning as the introduction path 64A opens to the recess 513 rather than the first joint surface 511 of the first segment 51.

[0040] Specifically, as shown in FIGS. 6 and 8 , a recess 513 that functions as a swirl chamber 63A is provided in the first joint surface 511 of the first segment 51. The recess 513 opens to the first joint surface 511 at a position away from the wall surface (male-side circumferential surface 41 or female-side circumferential surface 42) of the accommodation chamber 40. The first segment 51 is also provided with a communication hole 514 that functions as an injection hole 62A. The communication hole 514 connects the recess 513 of the first segment 51 with the accommodation chamber 40, and is provided at a position away from the first joint surface 511. Of the side walls of the recess 513, the side wall where the communication hole 514 opens and the opposing side wall form a first bottom surface 631 and a second bottom surface 632 of the swirl chamber 63A. The remaining side walls and bottom of the recess 513 form part of the circumferential wall 633 of the swirl chamber 63A.

[0041] As in the first embodiment, the first segment 51 is provided with a hole 512A that functions as the introduction path 64A. However, the hole 512A (inlet 642A of the introduction path 64A) opens into the recess 513 toward the first joint surface 511 of the first segment 51. The hole 512A (inlet 64A) is formed so that its projection area in the extension direction is connected to the recess 513 (swirl chamber 63A) at a position that does not overlap with the communication hole 514 (injection hole 62A). On the other hand, as shown in FIG. 7, the second segment 52 does not have any components of the liquid supply mechanism 60A formed therein. Note that in FIG. 7, the position corresponding to the opening of the recess 513 that appears on the first joint surface 511 of the first segment 51 facing the second joint surface 521 of the second segment 52 is indicated by a two-dot chain line.

[0042] In this modified example, the recess 513 and the hole 512A of the first segment 51 can be formed by machining the first joint surface 511 of the first segment 51. In addition, the communication hole 514 (ejection hole 62A) of the first segment 51 can be formed by machining the wall surface (male-side peripheral surface 41 or female-side peripheral surface 42) of the accommodation chamber 40 of the first segment 51.

[0043] When the first joint surface 511 of the first segment 51 and the second joint surface 521 of the second segment 52 are joined, the opening of the recess 513 in the first joint surface 511 of the first segment 51 is closed by the second joint surface 521 of the second segment 52. This forms a swirl chamber 63A. In this configuration, as shown in FIG. 7 , a portion of the second joint surface 521 of the second segment 52 becomes a portion of the peripheral wall 633 of the swirl chamber 63A.

[0044] In this way, in this modified example, the swirl chamber 63A is formed by utilizing the joint surfaces of the casing 4 that were separated in order to process the accommodation chamber 40, so that the swirl chamber 63A can be formed without drilling holes from the outer surface side of the casing 4. In other words, the structure is such that the swirl chamber 63A is formed without providing an opening that requires a sealing member on the outer surface side of the casing 4.

[0045] In the modified example of the first embodiment, an example of a configuration has been shown in which the injection hole 62A of the liquid supply mechanism 60A, the swirl chamber 63A, the communication hole 514 functioning as the introduction path 64A, the recess 513, and the hole 512A are all provided only in the first segment 51. However, a configuration is also possible in which the injection hole 62A of the liquid supply mechanism 60A, the swirl chamber 63A, the communication hole, the recess, and the hole functioning as the introduction path 64A are all provided only in the second segment 52.

[0046] As described above, the liquid feed screw compressor 1 according to the first embodiment and its modified examples includes the male rotor 2 and female rotor 3 as screw rotors rotatable around rotation axes A1 and A2 (axes), and a casing 4 having an accommodation chamber 40 therein that accommodates the male rotor 2 and the female rotor 3 (screw rotors), and having liquid feed mechanisms 60 and 60A in its wall portion for supplying liquid from outside to the accommodation chamber 40. The liquid feed mechanisms 60 and 60A include injection holes 62 and 62A that open to the accommodation chamber 40 and extend along a center line 621, swirl chambers 63 and 63A that are located upstream of the injection holes 62 and 62A and generate a swirling flow that swirls around an axis that extends in the same direction as the center line 621 of the injection holes 62 and 62A, and introduction paths 64 and 64A that introduce the liquid from outside into the swirl chambers 63 and 63A along the circumferential direction of the center line 621. The casing 4 is divided at a dividing plane P1 that intersects with the storage chamber 40, and includes a first casing segment 51 and a second casing segment 52 that are joined together. The swirl chambers 63, 63A are formed by recesses 513, 522 that are provided in the joining surfaces 511, 521 of one of the first casing segment 51 and the second casing segment 52 so as to open at positions away from the wall surfaces 41, 42 of the storage chamber 40. The introduction passages 64, 64A are formed by holes 512 that are provided so as to open at the joining surface 511 of the other casing segment 51 of the first casing segment 51 and the second casing segment 52, or holes 512A that are provided so as to open into the recess 513 toward the joining surface 511 of the casing segment 51 having the recess 522.

[0047] According to this configuration, the recesses 513, 522 opening to the joining surfaces 511, 521 of one of the first and second casing segments 51, 52 constitute the swirl chambers 63, 63A, and the hole 512 or recess 521 opening to the joining surface 511 of the other of the first and second casing segments 51, 52 constitute the swirl chambers 63, 63A. 13Since the hole 512A opening to the casing segments 51 and 52 forms the introduction passages 64 and 64A, it is possible to process the swirling chambers 63 and 63A and the introduction passages 64 and 64A from the joint surfaces 511 and 521 of the casing segments 51 and 52, and therefore the swirling chambers 63 and 63A can be formed within the wall of the casing 4 without providing an opening on the outer surface side of the casing 4.

[0048] This not only eliminates the possibility of liquid leakage to the outside of the casing 4, but also eliminates the need for a seal member to be attached to the opening and the processing required to attach the seal member, thereby reducing the number of steps required to manufacture the screw compressor 1. It also makes it possible to reduce the number of locations that need to be inspected for liquid leakage during regular inspections of the screw compressor 1.

[0049] In the liquid feed screw compressor 1 according to the first embodiment and its modified examples, the recesses 513, 522 are provided in only one of the first casing segment 51 and the second casing segment 52.

[0050] According to this configuration, the swirl chambers 63, 63 can be formed by machining only one of the first and second casing segments 51, 52, so that the number of machining steps for the swirl chambers 63, 63 can be reduced.

[0051] In addition, in the liquid supply type screw compressor 1 according to the first embodiment, the hole 512 is provided in the first casing segment 51 (the other casing segment) so as to open at a position where the joining surface 511 of the first casing segment 51 (the other casing segment) connects to the recess 522 of the second casing segment 52 (one casing segment).

[0052] According to this configuration, the hole portion 512 that functions as the introduction passage 64 can be formed by processing the joint surface 511 of the first casing segment 51 (the other casing segment) with a drill or the like, making it easy to process the introduction passage 64.

[0053] In addition, in the liquid supply type screw compressor 1 according to a modified example of the first embodiment, the hole portion 512A is provided in the first casing segment 51 (one of the casing segments) so as to open into the recess 513 toward the joining surface 511 of the first casing segment 51 (one of the casing segments).

[0054] According to this configuration, the recess 513 and hole 512A, which function as the swirling chamber 63A and the introduction path 64A of the liquid supply mechanism 60A, are formed only in the first segment 51, so that the effort required to set the casing segment 51 on the processing equipment when processing the recess 513 and hole 512A of the first segment 51 is reduced compared to when the recess 513 and hole 512A are formed in different casing segments.

[0055] [Second embodiment] Next, a screw compressor according to a second embodiment of the present invention will be described with reference to FIGS. 9 to 12. In FIGS. 9 to 12, the same reference numerals as those in FIGS. 1 to 8 denote similar parts, and detailed description thereof will be omitted. FIG. 9 is a longitudinal sectional view showing a schematic configuration of a screw compressor according to a second embodiment of the present invention. FIG. 10 is a sectional view of the screw compressor according to the second embodiment shown in FIG. 9, as viewed from the arrow XX. FIG. 11 is a view showing the structure of the joint surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the second embodiment shown in FIG. 10 is viewed from the arrow XI-XI. FIG. 12 is a view showing the structure of the joint surface on the other side of joined casing segments when the liquid supply mechanism of the screw compressor according to the second embodiment shown in FIG. 10 is viewed from the arrow XII-XII.

[0056] The liquid supply mechanism 60B of the screw compressor 1 of the second embodiment shown in Figures 9 and 10 differs from the liquid supply mechanism 60 of the screw compressor 1 of the first embodiment (see Figures 1 and 3) in that the positions of the injection holes 62B and the swirl chamber 63B of the liquid supply mechanism 60B relative to the dividing plane P1 of the casing 4 are different, and the shape of the swirl chamber 63B is different. The injection holes 62B and the swirl chamber 63B of the liquid supply mechanism 60B are formed on both sides of the dividing plane P1 of the casing 4. The swirl chamber 63B is configured in a shape formed by combining semi-cylindrical spaces.

[0057] Specifically, as shown in FIGS. 10 and 11 , the second joint surface 521 of the second segment 52 is provided with a second recess 522B that constitutes a part of the swirl chamber 63B, and a second groove 523B that connects the second recess 522B to the accommodation chamber 40. The second recess 522B opens to the second joint surface 521 at a position away from the wall surface (the male-side circumferential surface 41 or the female-side circumferential surface 42) of the accommodation chamber 40. The second recess 522B is formed, for example, as a semi-cylindrical space with an arc-shaped bottom and a substantially rectangular opening. The second recess 522B is formed, for example, so that its opening overlaps with the opening of a first recess 513B and the opening of a hole 512, which will be described later, in the first joint surface 511 of the first segment 51. The second groove portion 523B constitutes a part of the injection hole 62B and is provided at a position corresponding to a first groove portion 514B (described later) on the first joint surface 511 of the first segment 51. The opposing side walls of the second recess 522B form part of a first bottom surface 631 and part of a second bottom surface 632 of the swirl chamber 63B. The semi-cylindrical surface on the bottom side of the second recess 522B forms part of a peripheral wall 633 of the swirl chamber 63. In FIG. 11, the positions corresponding to a first recess 513B (described later) and a hole portion 512 (introduction passage 64) that appear on the first joint surface 511 of the first segment 51 facing the second joint surface 521 of the second segment 52 are indicated by two-dot chain lines.

[0058] As shown in FIGS. 10 and 12, the first joint surface 511 of the first segment 51 is provided with a first recess 513B that constitutes a part of the swirl chamber 63B, and a first groove 514B that connects the first recess 513B to the accommodation chamber 40. The first recess 513B opens to the first joint surface 511 at a position away from the wall surface (the male-side circumferential surface 41 or the female-side circumferential surface 42) of the accommodation chamber 40. The first recess 513B is formed, for example, as a semi-cylindrical space with an arc-shaped bottom and a substantially rectangular opening. The first recess 513B is configured, for example, to have a smaller diameter than the semi-cylindrical space of the second recess 522B, and its opening is formed at a position that overlaps with most of the opening of the second recess 522B in the second joint surface 521 of the second segment 52. The first groove portion 514B constitutes a part of the injection hole 62B, and is provided at a position corresponding to the second groove portion 523B of the second joint surface 521 of the second segment 52. Opposing side walls of the first recess 513B form a part of the first bottom surface 631 and a part of the second bottom surface 632 of the swirl chamber 63B. The semi-cylindrical surface on the bottom side of the first recess 513B forms a part of the peripheral wall 633 of the swirl chamber 63.

[0059] As in the first embodiment, a hole 512 (inlet 642 of the inlet passage 64) is formed in the first joint surface 511 of the first segment 51. The hole 512 is configured to open at a position adjacent to the opening of the first recess 513B on the first joint surface 511 of the first segment 51 and at a position connected to the second recess 522B of the second segment 52. The hole 512 (inlet passage 64) of the first segment 51 is connected to the second recess 522B (swirl chamber 63B) of the second segment 52 so that its projection area in the normal direction onto the joint surface 511 of the first segment 51 does not overlap with the first groove 514B and the second groove 523B (injection hole 62B). In FIG. 12, the position corresponding to the second recess 522B appearing on the second joint surface 521 of the second segment 52 opposite the first joint surface 511 of the first segment 51 is indicated by a two-dot chain line.

[0060] In the present embodiment, the second recess 522B and the second groove 523B of the second segment 52 can be formed by machining from the second joint surface 521 of the second segment 52. Similarly, the hole 512 (inlet passage 64), the first recess 513B, and the first groove 514B of the first segment 51 can be formed by machining from the first joint surface 511 of the first segment 51.

[0061] When the first joint surface 511 of the first segment 51 and the second joint surface 521 of the second segment 52 are joined, the opening of the second recess 522B in the second joint surface 521 of the second segment 52 is connected to the opening of the first recess 513B in the first joint surface 511 of the first segment 51 and is connected to the opening of the hole 512 in the first joint surface 511 of the first segment 51 (the inlet 642 of the introduction path 64). In addition, the first groove 514B in the first joint surface 511 of the first segment 51 is connected to the second groove 523B in the second joint surface 521 of the second segment 52. As a result, a swirl chamber 63B formed by the first recess 513B of the first segment 51 and the second recess 522B of the second segment 52 is formed, and an injection hole 62B formed by the first groove 514B of the first segment 51 and the second groove 523B of the second segment 52 is formed. The swirl chamber 63B is connected such that the introduction passage 64 is shifted from the connection position with the injection hole 62B.

[0062] In this manner, in the present embodiment, by forming swirl chamber 63B by utilizing the joint surfaces of casing 4 that were separated in order to process accommodation chamber 40, it is possible to form swirl chamber 63B without drilling holes from the outer surface side of casing 4. In other words, this structure allows swirl chamber 63B to be formed without providing an opening that requires a sealing member on the outer surface side of casing 4.

[0063] In order to generate an ideal swirling flow, the swirl chamber of the liquid supply mechanism is preferably a cylindrical space. However, in the first embodiment, since the swirl chamber 63 is provided only in the second segment 52, it is difficult to machine the joining surface 521 of the second segment 52 into a perfect cylindrical space.

[0064] In contrast, in this embodiment, by combining a first recess 513B, which is a semi-cylindrical space provided in the first joint surface 511 of the first segment 51, and a second recess 522B, which is a semi-cylindrical space provided in the second joint surface 521 of the second segment 52, it is possible to form a swirling chamber 63B having a shape similar to a cylindrical space.

[0065] In the second embodiment, an example of a configuration in which the hole 512 that functions as the introduction path 64 is provided in the first segment 51 has been shown. However, a configuration in which the hole 512 is provided in the second segment 52 is also possible. In this case, the relationship in size between the first recess 513B of the first segment 51 and the second recess 522B of the second segment 52 needs to be reversed.

[0066] [Modification of the second embodiment] Next, a liquid supply mechanism of a screw compressor according to a first modified example of the second embodiment will be described with reference to Figures 13 to 15. In Figures 13 to 15, the same reference numerals as those in Figures 1 to 12 denote similar parts, and detailed description thereof will be omitted. Figure 13 is a cross-sectional view of the structure of a liquid supply mechanism of a screw compressor according to a first modified example of the second embodiment, as viewed from the same direction as the arrow XX in Figure 9. Figure 14 is a diagram showing the structure of the joint surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the first modified example of the second embodiment shown in Figure 13 is viewed from the arrow XIV-XIV. Figure 15 is a diagram showing the structure of the joint surface on the other side of joined casing segments when the liquid supply mechanism of the screw compressor according to the first modified example of the second embodiment shown in Figure 13 is viewed from the arrow XV-XV.

[0067] Fluid supply mechanism 60C of a first modified example of the second embodiment shown in FIG. 13 differs from fluid supply mechanism 60B of the second embodiment (see FIG. 10) in that the position of injection hole 62C of fluid supply mechanism 60C relative to dividing surface P1 of casing 4 is different, the shape of swirl chamber 63C is different, and the opening position of hole 512C functioning as introduction path 64C is different. Injection hole 62C of fluid supply mechanism 60C is formed on the second segment 52 side rather than on both sides of dividing surface P1 of casing 4. Swirl chamber 63C is formed by combining semi-cylindrical spaces of the same size. Hole 512C (introduction path 64C) opens to first recess 513C rather than to first joint surface 511 of first segment 51.

[0068] Specifically, as shown in FIGS. 13 and 14 , the second joint surface 521 of the second segment 52 is provided with a second recess 522B that constitutes part of the swirl chamber 63C, as in the second embodiment. The second segment 52 is also provided with a communication hole 523C that functions as the injection hole 62C. The communication hole 523C connects the second recess 522B of the second segment 52 with the accommodation chamber 40, and is located away from the second joint surface 521. In FIG. 13 , the injection hole 62C that does not appear in the cross section is projected onto the cross section and indicated by a two-dot chain line. In FIG. 14 , the injection hole 62C that does not appear in the second joint surface 521 of the second segment 52 is indicated by a dashed line.

[0069] 13 and 15, a first recess 513C that constitutes part of the swirl chamber 63C is provided in the first joint surface 511 of the first segment 51. The first recess 513C is configured, for example, as a semi-cylindrical space having approximately the same size as the semi-cylindrical space of the second recess 522B, and its opening is formed at a position that coincides with the opening of the second recess 522B in the second joint surface 521 of the second segment 52. In other words, the first recess 513C of the first segment 51 and the second recess 522B of the second segment 52 have a plane-symmetric relationship with respect to the dividing plane P1 of the casing 4.

[0070] The first segment 51 is also provided with a hole 512C that functions as an introduction path 64C and opens into the first recess 513C. The hole 512C (inlet 642C of the introduction path 64C) opens in the first recess 513C toward the first joint surface 511 of the first segment 51. The hole 512C (introduction path 64C) is configured to be connected to the first recess 513C (swirl chamber 63C) at a position where, for example, its projected area in the normal direction of the second joint surface 521 of the second segment 52 does not overlap with the communication hole 523C (injection hole 62C).

[0071] In this modified example, the communication hole 523C (injection hole 62C) of the second segment 52 can be formed by machining the wall surface (male-side circumferential surface 41 or female-side circumferential surface 42) of the accommodation chamber 40 of the second segment 52. Also, the second recess 522B of the second segment 52 can be formed by machining the second joint surface 521 of the second segment 52. Similarly, the hole 512C (introduction passage 64C) and the first recess 513C of the first segment 51 can be formed by machining the first joint surface 511 of the first segment 51.

[0072] When the first joint surface 511 of the first segment 51 and the second joint surface 521 of the second segment 52 are joined, the opening of the first recess 513C in the first joint surface 511 of the first segment 51 is connected to the opening of the second recess 522B in the second joint surface 521 of the second segment 52. This forms a swirl chamber 63C, which is a substantially cylindrical space defined by the first recess 513C of the first segment 51 and the second recess 522B of the second segment 52.

[0073] In this manner, in this modified example, the swirl chamber 63C is formed by utilizing the joint surfaces of the casing 4 that were separated in order to process the accommodation chamber 40, so that the swirl chamber 63C can be formed without drilling holes from the outer surface side of the casing 4. In other words, the structure is such that the swirl chamber 63C is formed without providing an opening that requires a sealing member on the outer surface side of the casing 4.

[0074] Next, a liquid supply mechanism of a screw compressor according to a second modified example of the second embodiment will be described with reference to FIGS. 16 to 18. In FIGS. 16 to 18, the same reference numerals as those in FIGS. 1 to 15 denote similar parts, and detailed description thereof will be omitted. FIG. 16 is a cross-sectional view of the structure of a liquid supply mechanism of a screw compressor according to a second modified example of the second embodiment, as viewed from the same direction as the arrow XX in FIG. 9. FIG. 17 is a diagram showing the structure of the joining surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the second modified example of the second embodiment shown in FIG. 16 is viewed from the arrow XVII-XVII. FIG. 18 is a diagram showing the structure of the joining surface on the other side of joined casing segments when the liquid supply mechanism of the screw compressor according to the second modified example of the second embodiment shown in FIG. 16 is viewed from the arrow XVIII-XVIII.

[0075] Fluid supply mechanism 60D of a second modified example of the second embodiment shown in Figure 16 differs from fluid supply mechanism 60C of a first modified example of the second embodiment (see Figure 13) in that a communication hole functioning as injection hole 62D of fluid supply mechanism 60D is provided in first segment 51 rather than second segment 52. Other configurations of fluid supply mechanism 60D are similar to those of fluid supply mechanism 60C of the first modified example of the second embodiment.

[0076] Specifically, as shown in FIGS. 16 to 18, the first segment 51 is provided with a communication hole 514D that functions as an injection hole 62D. The communication hole 514D connects the first recess 513C of the first segment 51 with the housing chamber 40 and is located away from the first joint surface 511. The communication hole 514D (injection hole 62D) is connected to the first recess 513C so as not to overlap with the projection area of ​​the introduction passage 64C (hole portion 512C) of the first segment 51 in the normal direction of the second joint surface 521 of the second segment 52. The second segment 52 is provided with only a second recess 522B that constitutes part of the swirl chamber 63C. Note that in FIG. 16, the injection hole 62D that does not appear in the cross section is shown projected onto the cross section by a two-dot chain line. Also, in FIG. 18, the injection hole 62D that does not appear in the first joint surface 511 of the first segment 51 is shown by a dashed line.

[0077] In this modified example, the second recess 522B of the second segment 52 can be formed by machining from the second joint surface 521 of the second segment 52. Similarly, the hole 512C (inlet passage 64C) and the first recess 513C of the first segment 51 can be formed by machining from the first joint surface 511 of the first segment 51. In addition, the communication hole 514D (injection hole 62D) of the first segment 51 can be formed by machining from the wall surface (male-side circumferential surface 41 or female-side circumferential surface 42) of the accommodation chamber 40 of the first segment 51.

[0078] Next, a liquid supply mechanism of a screw compressor according to a third modified example of the second embodiment will be described with reference to Figures 19 to 21. In Figures 19 to 21, the same reference numerals as those in Figures 1 to 18 denote similar parts, and detailed description thereof will be omitted. Figure 19 is a cross-sectional view of the structure of a liquid supply mechanism of a screw compressor according to a third modified example of the second embodiment, as viewed from the same direction as the arrow XX in Figure 9. Figure 20 is a diagram showing the structure of the joint surface on one side of joined casing segments when the liquid supply mechanism of the screw compressor according to the third modified example of the second embodiment shown in Figure 19 is viewed from the arrows XX-XX. Figure 21 is a diagram showing the structure of the joint surface on the other side of joined casing segments when the liquid supply mechanism of the screw compressor according to the third modified example of the second embodiment shown in Figure 19 is viewed from the arrows XXI-XXI.

[0079] 19 differs from liquid supply mechanism 60B of the second embodiment (see FIG. 10) in that the positional relationship between swirl chamber 63E and introduction path 64E is different, and the shape of swirl chamber 63E is accordingly different. Hole 512E functioning as introduction path 64E is configured to open at a position on first joint surface 511 of first segment 51 away from the opening of first recess 513B and at a position connected to second recess 522E of second segment 52.

[0080] Specifically, as shown in FIGS. 19 and 21, an opening (inlet 642E) of a hole 512E functioning as an introduction path 64E is formed in the joint surface 511 of the first segment 51 at a position away from the opening of a first recess 513B that constitutes a part of the swirl chamber 63E. As shown in FIGS. 19 and 20, a second recess 522E that constitutes a part of the swirl chamber 63E is provided in the joint surface 521 of the second segment 52. The second recess 522E is configured so that its opening overlaps with the opening of the first recess 513B in the joint surface 511 of the first segment 51 and also overlaps with the opening of the hole 512E (inlet 642E of the introduction path 64E). That is, the second recess 522E is formed as a semi-cylindrical space having a larger radius than the first recess 513B. As in the second embodiment, a first groove 514B and a second groove 523B that function as injection holes 62B are provided on the joint surface 511 of the first segment 51 and the joint surface 521 of the second segment 52. In Fig. 20, the positions corresponding to the first recess 513B and the hole 512E (inlet passage 64E) that appear on the first joint surface 511 of the first segment 51 that faces the second joint surface 521 of the second segment 52 are indicated by two-dot chain lines. In Fig. 21, the positions corresponding to the second recess 522E that appear on the second joint surface 521 of the second segment 52 that faces the first joint surface 511 of the first segment 51 are indicated by two-dot chain lines.

[0081] In this modification, the second recess 522E and the second groove 523B of the second segment 52 can be formed by machining from the second joint surface 521 of the second segment 52. Similarly, the hole 512E (inlet passage 64E), the first recess 513B, and the first groove 514B of the first segment 51 can be formed by machining from the first joint surface 511 of the first segment 51.

[0082] When the first joint surface 511 of the first segment 51 and the second joint surface 521 of the second segment 52 are joined, the opening of the second recess 522E in the second joint surface 521 of the second segment 52 is connected to the opening of the first recess 513B in the first joint surface 511 of the first segment 51 and is also connected to the opening of the hole 512E (inlet 642E of the introduction path 64E) in the first joint surface 511 of the first segment 51. Furthermore, the first groove 514B in the first joint surface 511 of the first segment 51 is connected to the second groove 523B in the second joint surface 521 of the second segment 52. As a result, a swirl chamber 63E constituted by the first recess 513B of the first segment 51 and the second recess 522E of the second segment 52 is formed, and an injection hole 62B constituted by the first groove 514B of the first segment 51 and the second groove 523B of the second segment 52 is formed.

[0083] In this manner, in the present embodiment, swirl chamber 63E is formed by utilizing the joint surfaces of casing 4 that were separated in order to process accommodation chamber 40, so that swirl chamber 63E can be formed without drilling holes from the outer surface side of casing 4. In other words, this structure allows swirl chamber 63E to be formed without providing an opening that requires a seal member on the outer surface side of casing 4.

[0084] As described above, the liquid supply type screw compressor 1 according to the second embodiment and the first to third modified examples includes the male rotor 2 and the female rotor 3 as screw rotors that can rotate around the rotation axes A1 and A2 (axes), and a casing 4 that has an internal storage chamber 40 that houses the male rotor 2 and the female rotor 3 (screw rotors), and has liquid supply mechanisms 60B, 60C, 60D, and 60E in its wall portion for supplying liquid from the outside to the storage chamber 40. Liquid supply mechanisms 60B, 60C, 60D, 60E include injection holes 62B, 62C, 62D that open to storage chamber 40 and extend along center line 621, swirl chambers 63B, 63C, 63E that are located upstream of injection holes 62B, 62C, 62D and generate swirling flows that swirl around axes extending in the same direction as center line 621 of injection holes 62B, 62C, 62D, and introduction paths 64, 64C, 64E that introduce liquid from outside into swirl chambers 63B, 63C, 63E along the circumferential direction of center line 621. Casing 4 is divided by a dividing plane P1 that intersects storage chamber 40, and includes a first casing segment 51 and a second casing segment 52 that are joined to each other. The swirl chambers 63B, 63C, and 63E are formed by first recesses 513B and 513C and second recesses 522B and 522E (recesses) that are provided so as to open at positions away from the wall surfaces 41 and 42 of the accommodation chamber 40 in the joint surfaces 511 and 521 of both the first casing segment 51 and the second casing segment 52. The introduction paths 64, 64C, and 64E are formed by holes 512 and 512E that are provided so as to open at the joint surface 511 of the other casing segment 51 of the first casing segment 51 and the second casing segment 52, or by holes 512C that are provided so as to open into the first recess 513C toward the joint surface 511 of the casing segment 51 having the first recess 513C.

[0085] According to this configuration, the first recesses 513B, 513C and the second recesses 522B, 522E that open to the joining surfaces 511, 521 of the first and second casing segments 51, 52 constitute the swirl chambers 63B, 63C, 63E, and the first and second casing segments 51, 52 Our The holes 512, 512E or recesses 512A and 512B opening on the joining surface 51113C Since the hole 512C opening to the casing segments 51 and 52 forms the introduction passages 64, 64C, and 64E, it becomes possible to process the swirling chambers 63B, 63C, and 63E and the introduction passages 64, 64C, and 64E from the joint surfaces 511 and 521 of the casing segments 51 and 52, and therefore the swirling chambers 63B, 63C, and 63E can be formed within the wall of the casing 4 without providing an opening on the outer surface side of the casing 4.

[0086] In the liquid feed screw compressor 1 according to the second embodiment and its modified example, the first recesses 513B, 513C and the second recesses 522B, 522E are formed as semi-cylindrical spaces whose bottoms are arc surfaces.

[0087] According to this configuration, the swirling chambers 63B, 63C, 63E formed by the first recesses 513B, 513C and the second recesses 522B, 522E can easily generate a swirling flow that can break down the liquid into fine droplets.

[0088] In the screw compressor 1 with a liquid feed type according to the second embodiment and its modified example, the holes 512 and 512E are formed in the second recess 522B in the first joint surface 511 of the first segment 51. 、522E or at a position where the second segment 52 is connected to the first recess in the second joint surface 521 of the second segment 52.

[0089] According to this configuration, the hole portions 512, 512E that function as the introduction passages 64, 64E can be formed by processing the joint surface 511 of the first segment 51 or the joint surface 521 of the second segment 52 using a drill or the like, making it easy to process the introduction passages 64, 64E.

[0090] In addition, in the liquid supply type screw compressor 1 according to the second embodiment and its modified example, the hole portion 512 is configured to open at a position adjacent to the opening of the first recess 513B in the first joint surface 511 of the first segment 51 or at a position adjacent to the opening of the second recess in the second joint surface 521 of the second segment 52.

[0091] According to this configuration, the swirl chamber 63B formed by the first recess 513B and the second recess 522B can be formed relatively small.

[0092] In addition, in the liquid supply type screw compressor 1 according to the second embodiment and its modified example, the hole portion 512C is provided in the first segment 51 so as to open into the first recess 513C toward the first joint surface 511 of the first segment 51, or is provided in the second segment 52 so as to open into the second recess 522B toward the second joint surface 521 of the second segment 52.

[0093] With this configuration, even if a positional shift occurs when the first segment 51 and the second segment 52 are joined, there will be no shift in the positional relationship between the hole portion 512C and the first recess 513C or the second recess 522B due to the joining of the first segment 51 and the second segment 52.

[0094] Furthermore, in the liquid feed screw compressor 1 according to the second embodiment and its modified example, the first recessed portion 513C of the first segment 51 and the second recessed portion 522B of the second segment 52 have a plane-symmetric relationship with respect to the dividing plane P1 of the casing 4. According to this configuration, the swirling chamber 63C formed by the first recessed portion 513C and the second recessed portion 522B can easily generate a swirling flow that can break down liquid into fine droplets.

[0095] Furthermore, in the liquid feed screw compressor 1 according to the second embodiment and its modified example, the first segment 51 has a first groove portion 514B provided in the first joint surface 511 so as to connect the first recessed portion 513B and the storage chamber 40, and the second segment 52 has a second groove portion 523B provided in the second joint surface 521 at a position corresponding to the first groove portion 514B of the first segment 51 and connecting the second recessed portions 522B, 522E and the storage chamber 40. The injection hole 62B is formed by a combination of the first groove portion 514B of the first segment 51 and the second groove portion 523B of the second segment 52.

[0096] According to this configuration, it is possible to arrange the injection hole 62B near the center of the swirl chambers 63B, 63 formed by the first recess 513B and the second recesses 522B, 522E.

[0097] In the liquid feed screw compressor 1 according to the second embodiment and its modified example, the injection holes 62D, 62C are configured by a communication hole 514D provided in the first segment 51 to connect the first recess 513C of the first segment 51 to the storage chamber 40, or by a communication hole 523C provided in the second segment 52 to connect the second recess 522B of the second segment 52 to the storage chamber 40.

[0098] According to this configuration, the number of steps required to process the injection holes 62D and 62C can be reduced compared to when the injection hole 62B is formed by combining the first groove portion 514B of the first segment 51 and the second groove portion 523B of the second segment 52.

[0099] [Third embodiment] Next, a screw compressor according to a third embodiment will be described with reference to Fig. 22. In Fig. 22, the same reference numerals as those shown in Figs. 1 to 21 denote similar parts, and detailed description thereof will be omitted. Fig. 22 is a vertical cross-sectional view showing a schematic configuration of a screw compressor according to a third embodiment of the present invention. The screw compressor 1F of the third embodiment shown in Fig. 22 differs from the screw compressors 1 of the first and second embodiments (see Figs. 1 and 9) in that the dividing surface (dividing method) that divides the casing 4F is different, and the difference in dividing surface results in a different structure for the liquid supply mechanism 60F. The casing 4F has a half-split structure that is divided at a surface that includes the rotation axes A1, A2 of the male and female rotors 2, 3.

[0100] Specifically, the casing 4F includes a first segment 51F and a second segment (not shown) as casing segments separated by a dividing plane that includes the rotation axes A1, A2 of the male and female rotors 2, 3. In the present embodiment, a first joint surface 511F of the first segment 51F of the casing 4F is joined to a second joint surface (not shown) of the second segment, thereby forming a swirling chamber 63F and connecting an introduction passage 64F to the swirling chamber 63F.

[0101] Specifically, a first mating surface 511F of the first segment 51F is provided with a first recess 513F that constitutes a part of the swirl chamber 63F, and a first groove 514F that connects the first recess 513F and the storage chamber 40. Similarly, a second mating surface (not shown) of the second segment is provided with a second recess (not shown) that constitutes a part of the swirl chamber 63F, and a second groove (not shown) that connects the second recess and the storage chamber 40. The first recess 513F and the second recess open to the first mating surface 511F and the second mating surface at positions away from the wall surface (male-side circumferential surface 41 or female-side circumferential surface 42) of the storage chamber 40. The first groove 514F and the second groove constitute a part of the injection hole 62F.

[0102] Furthermore, a hole 512F (inlet passage 64F) opens in the first joint surface 511F of the first segment 51F. The hole 512F is configured to open at a position on the first joint surface 511F of the first segment 51F adjacent to the opening of the first recess 513F and at a position connected to the second recess of the second segment. The hole 512F (inlet passage 64F) of the first segment 51F is connected to the second recess of the second segment so that its projection area in the normal direction to the joint surface of the second segment does not overlap with the injection hole 62F. A liquid supply passage 61F is provided in the wall of the first segment 51F so as to be connected to the hole 512F.

[0103] In this embodiment, the hole 512F, the first recess 513F, and the first groove 514F of the first segment 51F can be formed by machining from the first bonding surface 511F of the first segment 51F. Similarly, the second recess and the second groove of the second segment can be formed by machining from the second bonding surface of the second segment.

[0104] In this manner, in the present embodiment, swirl chamber 63F can be formed without drilling holes from the outer surface side of casing 4F by forming swirl chamber 63F using joint surface 511F of casing 4F that was separated in order to process accommodation chamber 40. In other words, this structure allows swirl chamber 63F to be formed without providing an opening that requires a seal member on the outer surface side of casing 4F.

[0105] The liquid supply mechanism 60F of this embodiment may be the same as the liquid supply mechanisms 60B, 60C, 60D, and 60E of the modifications of the second embodiment and the liquid supply mechanism 60F of the first embodiment. and its variations Liquid supply mechanism 60 、60A It is also possible to change the structure to

[0106] As described above, the liquid feed screw compressor 1F according to the third embodiment includes the male rotor 2 and female rotor 3 as screw rotors rotatable about rotation axes A1, A2 (axes), and a casing 4F having an accommodation chamber 40 therein that accommodates the male rotor 2 and female rotor 3 (screw rotors), and having a liquid supply mechanism 60F in its wall for supplying liquid from outside to the accommodation chamber 40. The liquid supply mechanism 60F has injection holes 62F that open to the accommodation chamber 40, a swirl chamber 63F located upstream of the injection holes 62F, and an introduction passage 64F that introduces liquid into the swirl chamber 63F. The casing 4F is divided along a dividing plane that includes the rotation axes A1, A2 (axes) of the male rotor 2 and female rotor 3 (screw rotors), and includes a first casing segment 51F and a second casing segment that are joined to each other. The swirl chamber 63F is formed by a first recess 513F and a second recess provided in the joint surfaces 511F of both the first segment 51F and the second segment so as to open at positions away from the wall surfaces 41, 42 of the storage chamber 40. The introduction path 64F is formed by a hole 512F provided in the joint surface 511F of the first segment 51F of the second segment so as to open.

[0107] According to this configuration, the first recess 513F and the second recess 513F that open to the joining surface 511F of the first and second casing segments 51F constitute the swirl chamber 63F, and the first and second casing segments 51F Our Since the hole 512F opening into the joint surface 511F forms the introduction passage 64F, it is possible to process the swirling chamber 63F and the introduction passage 64F from the joint surface 511F of the casing segments 51, 52, and therefore the swirling chamber 63F can be formed within the wall portion of the casing 4F without providing an opening on the outer surface side of the casing 4F.

[0108] [Other embodiments] The present invention is not limited to the above-described embodiments, but includes various modifications. The above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. That is, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is also possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0109] In the first and second embodiments described above, an example has been shown in which the casing 4 of the screw compressor 1 is divided along a dividing plane P1 that is perpendicular to the rotation axes A1, A2 of the male and female rotors 2, 3. However, the casing may also be configured to include a plurality of casing segments that are divided along dividing planes that intersect the housing chamber 40 other than the planes perpendicular to the rotation axes A1, A2 of the male and female rotors 2, 3. For example, a configuration in which the dividing plane is a plane inclined with respect to the plane perpendicular to the rotation axes A1, A2 is possible. [Explanation of symbols]

[0110] REFERENCE SIGNS LIST 1, 1F...Screw compressor, 2...Male rotor (screw rotor), 3...Female rotor (screw rotor), 4, 4F...Casing, 40...Accommodation chamber, 41...Male side circumferential surface (wall surface), 42...Female side circumferential surface (wall surface), 51, 51F...First casing segment, 52...Second casing segment, 60, 60A, 60B, 60C, 60D, 60E, 60F...Liquid supply mechanism, 62, 62A, 62B, 62C, 62D, 62F...Injection holes, 63, 63A, 63B, 63C, 63E, 63F...Swirl chamber, 64, 64A, 64C, 64E, 64F...Introduction passage, 511, 511F...First joint surface, 521...Second joint surface, 512, 512A, 512C, 512E, 512F...hole portion, 513...recess portion, 513B, 513C, 513F...first recess portion, 514, 514D...communicating hole, 514B, 514F...first groove portion, 522...recess portion, 522B, 522E, 522F...second recess portion, 523, 523C...communicating hole, 523B...second groove portion, 621...center line, A1, A2...rotation axis (axis line)

Claims

1. a screw rotor rotatable around an axis; a casing having an internal storage chamber for storing the screw rotor and a liquid supply mechanism in a wall portion for supplying liquid from outside to the storage chamber; The liquid supply mechanism includes: an injection hole that opens into the accommodation chamber and extends along a center line; a swirl chamber located upstream of the injection hole and configured to generate a swirling flow swirling around an axis extending in the same direction as the center line of the injection hole; an introduction passage for introducing a liquid from the outside into the swirl chamber; the casing includes a first casing segment and a second casing segment that are joined together and are divided along a dividing plane that crosses the accommodation chamber or a plane that includes the axis of the screw rotor; the swirl chamber is configured by a recess provided in a joint surface of one of the first casing segment and the second casing segment so as to open at a position away from a wall surface of the accommodation chamber, The introduction path is configured by a hole provided so as to open to the joining surface of the other of the first casing segment and the second casing segment, or a hole provided so as to open to the recess toward the joining surface side of the casing segment having the recess. A liquid feed screw compressor characterized by the above.

2. 2. The liquid feed screw compressor according to claim 1, The hole is provided in the other casing segment so as to open at a position on the joining surface of the other casing segment where the hole is connected to the recess of the one casing segment. A liquid feed screw compressor characterized by the above.

3. 2. The liquid feed screw compressor according to claim 1, The hole is provided in the one casing segment so as to open into the recess toward the joining surface side of the one casing segment. A liquid feed screw compressor characterized by the above.

4. a screw rotor rotatable around an axis; a casing having an internal storage chamber for storing the screw rotor and a liquid supply mechanism in a wall portion for supplying liquid from outside to the storage chamber; The liquid supply mechanism includes: an injection hole that opens into the accommodation chamber and extends along a center line; a swirl chamber located upstream of the injection hole and configured to generate a swirling flow swirling around an axis extending in the same direction as the center line of the injection hole; an introduction passage for introducing a liquid from the outside into the swirl chamber; the casing includes a first casing segment and a second casing segment that are joined together and are divided along a dividing plane that crosses the accommodation chamber or a plane that includes the axis of the screw rotor; the swirl chamber is configured by a recess having: a first recess provided in the first casing segment so as to open to a first joint surface of the first casing segment; and a second recess provided in the second casing segment so as to open at a position connected to the first recess of the first casing segment on a second joint surface of the second casing segment, the introduction path is configured by a hole portion provided so as to open to one of the first joint surface of the first casing segment and the second joint surface of the second casing segment, The hole is configured to open at a position on the first joining surface of the first casing segment that is connected to the second recess, or at a position on the second joining surface of the second casing segment that is connected to the first recess. A liquid feed screw compressor characterized by the above.

5. 5. The liquid feed screw compressor according to claim 4, The hole is configured to open at a position adjacent to an opening of the first recess in the first joining surface of the first casing segment or at a position adjacent to an opening of the second recess in the second joining surface of the second casing segment. A liquid feed screw compressor characterized by the above.

6. 5. The liquid feed screw compressor according to claim 4, The first recess and the second recess are formed as semi-cylindrical spaces whose bottoms are arcuate surfaces. A liquid feed screw compressor characterized by the above.

7. 5. The liquid feed screw compressor according to claim 4, the first casing segment has a first groove portion provided in the first joint surface so as to connect the first recess portion and the accommodating chamber, the second casing segment has a second groove portion provided at a position on the second joint surface corresponding to the first groove portion of the first casing segment, the second groove portion connecting the second recess and the accommodating chamber, The injection hole is formed by a combination of the first groove portion of the first casing segment and the second groove portion of the second casing segment. A liquid feed screw compressor characterized by the above.

8. a screw rotor rotatable around an axis; a casing having an internal storage chamber for storing the screw rotor and a liquid supply mechanism in a wall portion for supplying liquid from outside to the storage chamber; The liquid supply mechanism includes: an injection hole that opens into the accommodation chamber and extends along a center line; a swirl chamber located upstream of the injection hole and configured to generate a swirling flow swirling around an axis extending in the same direction as the center line of the injection hole; an introduction passage for introducing a liquid from the outside into the swirl chamber; the casing includes a first casing segment and a second casing segment that are joined together and are divided along a dividing plane that crosses the accommodation chamber or a plane that includes the axis of the screw rotor; the swirl chamber is configured by a recess having: a first recess provided in the first casing segment so as to open to a first joint surface of the first casing segment; and a second recess provided in the second casing segment so as to open at a position connected to the first recess of the first casing segment on a second joint surface of the second casing segment, the introduction path is configured by a hole portion provided so as to open into one of the first joint surface of the first casing segment and the second joint surface of the second casing segment, or a hole portion provided so as to open into one of the first recess and the second recess toward the first joint surface of the first casing segment having the first recess and the second joint surface of the second casing segment having the second recess, The injection hole is constituted by a communication hole provided in the first casing segment so as to communicate the first recess of the first casing segment with the accommodating chamber, or a communication hole provided in the second casing segment so as to communicate the second recess of the second casing segment with the accommodating chamber. A liquid feed screw compressor characterized by the above.

9. 9. The liquid feed screw compressor according to claim 8, the hole is provided in the first casing segment so as to open into the first recess toward the first joining surface side of the first casing segment, or the hole is provided in the second casing segment so as to open into the second recess toward the second joining surface side of the second casing segment, The first recess of the first casing segment and the second recess of the second casing segment are in a plane-symmetrical relationship with respect to the dividing plane. A liquid feed screw compressor characterized by the above.

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