Screw compressor

Abstract

To obtain a screw compressor having a liquid supply mechanism which can supply a liquid which is made into sufficiently small droplets to an air compression chamber.SOLUTION: A screw compressor 100 of the invention includes a screw rotor 1 and a casing 4 which houses the screw rotor and is provided with a liquid supply mechanism 40 which supplies a liquid 50 to the inside of a compression chamber 13 formed in the casing. In the liquid supply mechanism 40, a vertical wall surface 422 formed along a depth direction of a recessed part 41 and an outlet 441 of a liquid introduction passage 44 which is open facing the vertical wall surface are disposed in a first area 42 at the bottom side of the recessed part which is open on a casing inner surface 4a. A folded surface 431 wich is folded in a border portion with the vertical wall surface and continues in a direction away from the outlet of the liquid introduction passage is disposed in a second area 43 at the casing inner surface side of the recessed part, which continues into the first area 42.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] A screw compressor is a device that compresses gas, such as air. A screw compressor is a device that generates compressed gas by meshing two screw-shaped male and female rotors. In order to increase the gas compression efficiency, a liquid supply mechanism that injects liquid such as oil into a gas compression chamber formed in a casing that houses the male and female screw rotors is provided in the screw compressor. The liquid injected into the gas compression chamber from the liquid supply mechanism cools the compressed gas through heat exchange and reduces gas leakage from gaps between the screw rotors and between the screw rotors and the casing.

[0003] A conventional mechanism for supplying liquid into a gas compression chamber will now be described. When ejecting liquid, one method for forming the liquid into minute droplets is to utilize the collision energy of the liquid.

[0004] As disclosed in Patent Document 1 below, there is a technology for a liquid supply mechanism in which a liquid supply nozzle has a pair of injection holes that collide the injected liquid to spread it over a surface, and a groove portion whose side wall surfaces are a first inclined surface and a second inclined surface that gradually approach each other toward the bottom, and the liquid injected from the pair of injection holes collides to break the liquid into fine droplets.

[0005] Furthermore, as disclosed in Patent Document 2 below, there is a liquid supply mechanism technology in which an inclined surface onto which the liquid collides is provided in a location other than the space of the oil supply hole, and the liquid flowing out of the inclined orifice collides with the inclined surface to form a fan-shaped spray pattern, breaking the liquid into fine droplets. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-85389 [Patent Document 2] US 2019 / 0093659 A1 Summary of the Invention [Problem to be solved by the invention]

[0007] In order to use a liquid supply mechanism to cool the compressed gas and reduce gas leakage from the gaps between the screw rotors and the gap between the screw rotor and the casing, it is necessary to turn the liquid ejected from the liquid injection nozzle into fine droplets and supply them to the air compression space. However, the technologies in Patent Documents 1 and 2 have the following problems.

[0008] In the method of injecting liquid from a pair of injection holes and colliding them as in Patent Document 1, a liquid film is first formed by the collision, and then the liquid starts to break down into fine droplets from the tip of the liquid film. Therefore, the length of breakup from when the liquid comes out of the injection hole to when it breaks up into fine droplets is long, so the liquid comes into contact with the rotor in the liquid film state before it breaks up into fine droplets, which poses the problem of insufficient breakup into fine droplets.

[0009] In Patent Document 2, an inclined surface onto which the liquid collides is provided in a location other than the space of the oil supply hole, and similarly to Patent Document 1, the liquid comes into contact with the rotor in the form of a liquid film, which poses the problem that the liquid cannot be sufficiently broken down into small droplets.

[0010] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide a screw compressor having a liquid supply mechanism capable of supplying liquid in the form of sufficiently fine droplets to an air compression chamber. [Means for solving the problem]

[0011] The screw compressor of the present invention which solves the above problems comprises: A screw compressor including a screw rotor and a casing that houses the screw rotor, and a liquid supply mechanism that supplies liquid into a compression chamber formed in the casing, The liquid supply mechanism includes: a vertical wall surface along a depth direction of the recess and an outlet of the liquid introduction flow path opening opposite to the vertical wall surface are disposed in a first region on the bottom side of the recess that opens on the inner surface of the casing; a second region on the inner surface side of the casing of the recess, which is continuous with the first region, is bent at the boundary with the vertical wall surface, and a bent surface is arranged so as to continue in a direction away from the outlet of the liquid introduction flow path. Effect of the Invention

[0012] According to the screw compressor of the present invention, it is possible to sufficiently convert liquid into fine droplets by the liquid supply mechanism and supply the liquid to the air compression chamber. Further features related to the present invention will become apparent from the description of this specification and the attached drawings. In addition, problems, configurations and effects other than those described above will become apparent from the description of the following embodiments. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing the configuration of a screw compressor according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the screw rotor and the liquid supply mechanism taken along line II-II in FIG. 1 . [Diagram 3] FIG. 2 is a diagram showing the arrangement of a liquid supply mechanism in the screw compressor according to the first embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing the configuration of a liquid supply mechanism of the screw compressor according to the first embodiment. [Diagram 5] FIG. 2 is a diagram illustrating a liquid supplying method by a liquid supply mechanism of the screw compressor according to the first embodiment. [Figure 6] 6 is a diagram showing the liquid supply mechanism of the screw compressor according to the first embodiment, as viewed from the direction of arrow VI in FIG. 5. [Figure 7A] 11A and 11B are diagrams showing an example of the configuration of one vertical wall surface of a liquid supply mechanism. [Figure 7B] 11A and 11B are diagrams showing an example of the configuration of one vertical wall surface of a liquid supply mechanism. [Figure 7C] 11A and 11B are diagrams showing an example of the configuration of one vertical wall surface of a liquid supply mechanism. [Figure 8] FIG. 6 is a cross-sectional view showing a configuration of a liquid supply mechanism of a screw compressor according to a second embodiment. [Figure 9] 13A to 13C are diagrams illustrating a liquid supplying method by a liquid supply mechanism of a screw compressor according to a second embodiment. [Figure 10] FIG. 11 is a cross-sectional view showing the configuration of a liquid supply mechanism of a screw compressor according to a third embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing the configuration of a liquid supply mechanism of a screw compressor according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of a liquid supply mechanism for a screw compressor according to the present invention will be described with reference to the drawings. In each drawing, the same elements are denoted by the same reference numerals, and duplicated description will be omitted. Note that the present invention is not limited to each of the embodiments described below, and various modified examples are included. For example, the embodiments described below are described in detail to easily explain the present invention, and are not necessarily limited to those including all of the configurations. In addition, it is possible to replace a 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. In addition, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0015] First Embodiment FIG. 1 is a diagram showing the configuration of a screw compressor according to the first embodiment, FIG. 2 is a cross-sectional view of the screw rotor and the vicinity of a liquid supply mechanism taken along line II-II in FIG. 1, and FIG. 3 is a diagram showing the arrangement of the liquid supply mechanism in the screw compressor according to the first embodiment.

[0016] 1, a screw compressor 100 according to this embodiment includes a screw rotor 1 and a casing 4 that houses the screw rotor 1. The screw rotor 1 includes a male rotor 2 and a female rotor 3 that have twisted teeth (lobes) and rotate while meshing with each other, and the term "male rotor" is used as a general term for these rotors.

[0017] The screw compressor 100 is equipped with a suction side bearing 5 and a discharge side bearing 6 for rotatably supporting the male rotor 2 and the female rotor 3, respectively, and shaft sealing parts 7 such as oil seals and mechanical seals. An inlet 14 opens at an inlet side end face 28 in the casing 4, and a discharge port 15 opens at a discharge side end face 29. Here, the "suction side" refers to the side on which a gas such as air is suctioned in the axial direction of the screw rotor 1, and the "discharge side" refers to the side on which a gas is discharged in the axial direction of the screw rotor 1.

[0018] Typically, the suction side end of the male rotor 2 is connected to a motor 8, which is a rotation drive source, via a rotor shaft. A cylindrical male side bore 9 that covers the male rotor 2 and a cylindrical female side bore 10 that covers the female rotor 3 are formed on the inner surface 4a of the casing 4. The male rotor 2 and the female rotor 3 are housed in the casing 4 with a gap of several tens of μm to several hundreds of μm relative to the male side bore 9 and the female side bore 10 of the casing 4, respectively. There are two intersection lines between the male side bore 9 and the female side bore 10, and the intersection line on the low pressure side is defined as the suction side cusp 11, and the intersection line on the high pressure side is defined as the compression side cusp (compression side intersection line) 12.

[0019] The male rotor 2, driven to rotate by the motor 8, drives the female rotor 3 to rotate, and a compression chamber 13 formed by the tooth grooves of the male rotor 2 and the female rotor 3 and the male bore 9 and the female bore 10 surrounding them expands and contracts. As a result, a gas such as air is sucked in through the suction port 14, compressed to a predetermined pressure, and then discharged from the discharge port 15.

[0020] A liquid such as lubricating oil is injected from the outside of screw compressor 100 into compression chamber 13, suction side bearing 5, discharge side bearing 6, and shaft seal component 7 through liquid supply hole 16, suction side bearing liquid supply hole 17, and discharge side bearing liquid supply hole 18. Discharge air 60 discharged from discharge port 15 is separated into a gas such as air and a liquid such as lubricating oil by centrifugal oil separator 61, and the liquid is cooled to an appropriate temperature by cooler 62 and then used for supply again.

[0021] The screw compressor 100 is provided with a liquid supply mechanism 40 that supplies a liquid such as a lubricating oil into the compression chamber 13 formed in the casing. The liquid supply mechanisms 40 are attached to the tip of the liquid supply hole 16, and in this embodiment, as shown in Fig. 3, three liquid supply mechanisms 40 are attached to each of the male rotor 2 and the female rotor 3 at predetermined intervals in the axial direction.

[0022] Next, the configuration of the liquid supply mechanism will be described. Figure 4 is a cross-sectional view showing the configuration of the liquid supply mechanism of the screw compressor according to the first embodiment. In this embodiment, liquid supply mechanisms 40 are provided on both the male rotor 2 side and the female rotor 3 side, but since these have the same configuration, in the following explanation, only the configuration of the liquid supply mechanism 40 provided on the male rotor 2 side will be explained, and the configuration of the liquid supply mechanism 40 on the female rotor 3 side will be omitted.

[0023] The liquid supply mechanism 40 has a recess 41 that opens to the casing inner surface 4a. The liquid supply mechanism 40 may be structured to be formed integrally with the casing 4, or may be structured to be capable of being formed separately from the casing 4 in consideration of workability and maintainability. In this embodiment, the recess 41 has a structure formed in a recess main body 411 that is configured separately from the casing 4.

[0024] The recess 41 has a groove shape extending along the tooth grooves of the male rotor 2 and the female rotor 3 (see FIG. 3), and has a first region 42 located on the bottom side in the depth direction of the recess 41, and a second region 43 continuous with the first region 42 and located on the casing inner surface 4a side of the recess 41. A liquid collision space is formed in the first region 42, where the liquid 50 is caused to collide with the vertical wall surface 422, and a liquid breakup space is formed in the second region 43, where the liquid film 51 is broken up into ligaments 52 and droplets 53.

[0025] The first region 42 of the recess 41 is formed with a recess bottom surface 421 parallel to the casing inner surface 4a, and a pair of vertical wall surfaces 422, 423 rising from both sides in the groove width direction of the recess bottom surface 421 and extending in the depth direction of the recess 41. Of the pair of vertical wall surfaces 422, 423, one vertical wall surface 422 is disposed so as to be located forward in the rotation direction F of the male rotor 2, and the other vertical wall surface 423 is disposed so as to be located rearward in the rotation direction F of the male rotor 2 relative to the one vertical wall surface 422. In other words, one vertical wall surface 422 is disposed in a position facing the rotation direction of the screw rotor 1.

[0026] The liquid supply mechanism 40 has a liquid introduction flow passage 44 for introducing liquid into the recess 41 from the outside of the casing 4. An outlet 441 of the liquid introduction flow passage 44 is opened in the bottom surface 421 of the recess. The outlet 441 of the liquid introduction flow passage 44 is disposed at a position that opens opposite to one vertical wall surface 422. The liquid introduction flow passage 44 is formed toward the one vertical wall surface 422, that is, it is provided so as to extend in a direction gradually approaching the one vertical wall surface 422 as it moves toward the outlet 441. The liquid introduction flow passage 44 is formed inclined at a predetermined inclination angle θa with respect to the one vertical wall surface 422 so that the liquid ejected from the outlet 441 obliquely hits the one vertical wall surface 422 from the bottom side of the recess 41 toward the opening side of the recess 41 along the depth direction of the recess 41. The inclination angle θa is set to an angle smaller than the vertical. The base end of the inlet of the liquid introduction flow passage 44 is connected to a liquid container 63 such as a common rail. The liquid stored in the liquid container 63 is supplied to the liquid supply mechanism 40 .

[0027] The second region 43 of the recess 41 has a structure in which a bent surface 431 is arranged, which is bent at a boundary portion with one vertical wall surface 422 and continues in a direction away from the outlet 441 of the liquid introduction flow channel 44. The bent surface 431 is bent at a predetermined angle θb with respect to the one vertical wall surface 422, and an edge 432 is formed at the boundary portion with the one vertical wall surface 422. In this embodiment, the bent surface 431 is bent vertically in a step shape at the boundary portion with the one vertical wall surface 422, and is a discontinuous surface with respect to the one vertical wall surface 422. Then, a vertical wall surface 433 is provided which is bent at an end of the bent surface 431 toward the casing inner surface 4a and rises up.

[0028] Further, in the second region 43 of the recess 41, an inclined surface 434 is formed which is bent at the boundary with the other vertical wall surface 423 and continues in a direction away from the one vertical wall surface 422. The inclined surface 434 is bent at a predetermined angle θc with respect to the other vertical wall surface 423. The inclined surface 434 is inclined so as to transition from the casing inner surface 4a to the recess bottom surface 421 of the recess 41 as it transitions along the rotation direction of the screw rotor 1. The angle θc of the inclined surface 434 is set to an inclination angle at which the gas pushed out by the male rotor 2 in the compression chamber 13 and moving along the casing inner surface 4a can smoothly flow into the recess 41.

[0029] Next, a liquid supplying method by liquid supply mechanism 40 will be described with reference to FIGS. FIG. 5 is a diagram for explaining a liquid supplying method by the liquid supply mechanism of the screw compressor according to the first embodiment, and FIG. 6 is a diagram showing the liquid supply mechanism of the screw compressor according to the first embodiment as viewed from the direction of arrow VI in FIG. 5.

[0030] Liquid is stored in liquid container 63 in a state where it is pressurized to a predetermined pressure, and is supplied from liquid container 63 to liquid introduction flow path 44. Liquid 50 supplied to liquid introduction flow path 44 is sprayed from outlet 441 into first region 42 of recess 41, collides with one vertical wall surface 422 facing outlet 441, and forms a thin liquid film 51 that moves along one vertical wall surface 422 within first region 42.

[0031] The thin liquid film 51 moving along one vertical wall surface 422 in this manner within the first region 42 passes through an edge 432 formed at the boundary between one vertical wall surface 422 and the bent surface 431 and enters the second region 43. Here, the one vertical wall surface 422 and the bent surface 431 are bent in a step shape at the edge 432, forming a discontinuous surface.

[0032] Therefore, when the liquid film 51 enters the second region 43, it does not move along the bent surface 431, but breaks off from the vertical wall surface 422 by its own inertial force and is discharged into the air in the second region 43 of the recess 41. The liquid film 51 discharged into the air is broken into ligaments 52 and droplets 53 in the second region 43 due to disturbances caused by the airflow in the air and instability of the surface tension generated on the surface of the liquid film 51. Then, the liquid film 51 is supplied from the recess 41 into the compression chamber 13 in a state where it has been sufficiently broken into minute droplets in the second region 43. Therefore, the cooling performance of the compressed air in the compression chamber 13 and the sealing performance of the gaps in each part are improved.

[0033] In this embodiment, an inclined surface 434 is formed which is bent at the boundary with the other vertical wall surface 423 and continues in a direction away from the one vertical wall surface 422. This inclined surface 434 can smoothly introduce air A, which is pushed out by the male rotor 2 in the compression chamber 13 and moves along the casing inner surface 4a, into the second region 43 of the recess 41. In other words, the inclined surface 434 forms an air introduction passage that introduces air into the recess 41.

[0034] This increases the disturbance caused by the airflow in the air, and makes it possible to promote the breakup of the thin liquid film 51 in the second region 43 of the recess 41. Due to the above-mentioned action and effect, when the liquid is sprayed from the liquid supply mechanism 40, the liquid is sufficiently broken down into fine droplets, and the cooling performance of the compressed air and the sealing performance of the gaps in each part are improved.

[0035] According to the screw compressor 100 of this embodiment, the droplets are miniaturized and the total surface area of ​​the droplets is increased, so that the compressed gas is cooled and the density is increased, thereby improving the compression efficiency. In addition, the droplets are miniaturized and dispersed over a wide area in the air compression chamber, so that the liquid adheres uniformly to the gaps between the screw rotors and the gaps between the screw rotors and the casing, thereby making it possible to reduce gas leakage from the gaps.

[0036] Furthermore, according to the screw compressor 100 of this embodiment, the liquid supply mechanism 40 is disposed so that the long axis direction of the liquid spray from the liquid supply mechanism 40 is parallel to the ridge line of the screw tooth tips 2a, 3a, as shown in Fig. 3. Since the liquid droplets are sprayed in an elliptical shape from the recess 41 of the liquid supply mechanism 40, the long axis direction of the ellipse can be made parallel to the ridge line of the screw tooth tips, making it possible to more uniformly distribute the liquid droplets within the space, leading to improved cooling and sealing effects.

[0037] FIG. 7A is a diagram for explaining a configuration example of one vertical wall surface of the liquid supply mechanism, and shows the shape of thin liquid film 51 formed in the cross section taken along line VII-VII in FIG. In this configuration example, the vertical wall surface 422 has a flat surface portion 422A. Therefore, when the liquid 50 is collided with the flat surface portion 422A of the vertical wall surface 422, it can be quickly spread in the direction away from each other from the collision position in the longitudinal direction of the recess 41, forming a thin liquid film 51 and facilitating the formation of fine droplets. In addition, the flat surface portion 422A is easy to process, and the man-hours required for forming the vertical wall surface 422 can be reduced.

[0038] FIG. 7B is a diagram showing another example of the configuration of one vertical wall surface of the liquid supply mechanism, and shows the shape of thin liquid film 51 formed in the cross section taken along line VII-VII in FIG. In the configuration example shown in FIG. 7B, the vertical wall surface 422 has a concave curved surface portion 422B that is concavely curved in a direction away from the outlet 441 of the liquid introduction flow path 44. The concave curved surface portion 422B is formed along the longitudinal direction of the recess 41, and has a concave curved surface shape that is concavely curved in a direction perpendicular to the liquid ejection direction. This increases the force with which the thin liquid film 51 is pressed against the liquid collision surface 33, making it possible to thin the liquid film from a position closer to the collision position, and thus forming a more uniform and thinner liquid film. As a result, it is possible to promote the formation of finer droplets.

[0039] FIG. 7C is a diagram showing another example of the configuration of one vertical wall surface of the liquid supply mechanism, and shows the shape of thin liquid film 51 formed in the cross section taken along line VII-VII in FIG. In the configuration example shown in FIG. 7C, the vertical wall surface 422 has a convex curved surface portion 422C that is curved convexly in a direction away from the outlet 441 of the liquid introduction flow path 44 and protrudes like a hill. The convex curved surface portion 422C is formed along the longitudinal direction of the recess 41 and has a convex curved surface shape that is curved convexly in a direction perpendicular to the liquid injection direction. Therefore, when the liquid 50 collides with the vertical wall surface 422, the liquid film 51 can be spread over a wider range. This makes it possible to diffuse fine droplets from the liquid supply mechanism 40 over a wider range, leading to improved cooling and sealing effects of the screw compressor 100.

[0040] <Second embodiment> Next, a screw compressor according to a second embodiment will be described. Fig. 8 is a cross-sectional view showing the configuration of a liquid supply mechanism of the screw compressor according to the second embodiment, and Fig. 9 is a diagram explaining a liquid supply method by the liquid supply mechanism of the screw compressor according to the second embodiment.

[0041] A characteristic feature of this embodiment is that the second region 43 of the recess 41 has a bent surface 435 inclined with respect to the vertical wall surface 422. The bent surface 435 has a planar shape that is bent at the boundary with one of the vertical wall surfaces 422 and continues in a direction away from the outlet 441 of the liquid introduction channel 44. The bent surface 435 is disposed at a position facing the rotation direction of the screw rotor 1.

[0042] The bent surface 435 is bent at a predetermined angle θb with respect to one vertical wall surface 422, and an edge 432 is formed at the boundary with the one vertical wall surface 422. In this embodiment, the bent surface 435 is bent in a tapered shape at the boundary with the one vertical wall surface 422, and is inclined so as to gradually move in a direction away from the outlet 441 as it moves from the boundary to the casing inner surface 4a, and is a surface that is discontinuous with the one vertical wall surface 422.

[0043] Therefore, when the liquid 50 collides with the vertical wall surface 422 to form a liquid film 51, the liquid 50 does not move along the bent surface 431 when entering the second region 43, but breaks off from the vertical wall surface 422 by its own inertial force and is discharged into the air in the second region 43 of the recess 41. The liquid film 51 discharged into the air is broken into ligaments 52 and droplets 53 in the second region 43 due to disturbances caused by the airflow in the air and instability of the surface tension generated on the surface of the liquid film 51. Then, the liquid is supplied from the recess 41 into the compression chamber 13 in a state of being sufficiently broken into minute droplets in the second region 43. Therefore, the cooling performance of the compressed air in the compression chamber 13 and the sealing performance of the gaps in each part are improved.

[0044] The recess 41 has a tapered opening formed by the bent surface 435 and the inclined surface 434. In this embodiment, the inclination angle θb of the bent surface 435 is smaller than the inclination angle θc of the inclined surface 434 bent at the boundary portion with the other vertical wall surface 423 with respect to the vertical wall surface 423 (θb<θc). In other words, when the inclination angle θb of the bent surface 435 is compared with the inclination angle θc of the inclined surface 434, the inclination angle θc of the inclined surface 434 with respect to the depth direction of the recess 41 is larger.

[0045] In other words, the inclination angle θc of the inclined surface 434 located on the upstream side of the airflow moving along the casing inner surface 4a is larger than the inclination angle θb of the bent surface 435 located on the downstream side of the airflow. Therefore, more of the gas pushed out by the male rotor 2 in the compression chamber 13 and moving along the casing inner surface 4a can be actively made to flow into the recess 41, thereby generating strong disturbance by the airflow.

[0046] <Third and fourth embodiments> Next, screw compressors according to third and fourth embodiments will be described. Figures 10 and 11 are diagrams showing the configuration of a liquid supply mechanism of a screw compressor according to a third embodiment. The screw compressor shown in Figure 10 and the screw compressor shown in Figure 11 have the same configuration except that the inclination angle of the bent surface is different as in the first and second embodiments.

[0047] A feature of this embodiment is that the inclination angle θa of the vertical wall surface 422 is made larger than in the first and second embodiments described above, thereby increasing the angle at which the liquid ejected from the outlet 441 collides with the vertical wall surface 422. The inclination angle θa is an angle smaller than perpendicular to the vertical wall surface 422 and is larger than the angles in the first and second embodiments.

[0048] The vertical wall surface 422 gradually inclines toward the outlet 441 as it approaches the second region 43 from the bottom surface 421 of the recess (inclined to the right as it goes up in FIG. 6). That is, the vertical wall surface 422 is inclined in a reverse tapered shape so as to gradually move in a direction approaching the outlet 441 of the liquid introduction flow path 44 as it moves from the bottom side of the recess 41 toward the casing inner surface 4a along the depth direction of the recess 41. This increases the pressing force that causes the liquid ejected from the outlet 441 to collide with the vertical wall surface 423, and the thin liquid film 51 becomes even thinner as it approaches the second region 43. As a result, the liquid is further promoted from being broken down into fine droplets.

[0049] Although the embodiments of the present invention have been described above in detail, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the configurations described. In addition, it is possible to replace a 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 possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0050] DESCRIPTION OF SYMBOLS 1 Screw rotor, 4 Casing, 4a Casing inner surface, 13 Compression chamber, 40 Liquid supply mechanism, 41 Recess, 42 First region (liquid collision space), 43 Second region (liquid split space), 44 Liquid introduction passage, 100 Screw compressor, 421 Recess bottom, 422 Vertical wall, 422B Concave curved surface, 422C Convex curved surface, 431, 435 Bent surface, 432 Edge, 441 Outlet, 434 Inclined surface

Claims

1. A screw compressor including a screw rotor and a casing that houses the screw rotor, and a liquid supply mechanism that supplies liquid into a compression chamber formed in the casing, The liquid supply mechanism includes: a vertical wall surface along a depth direction of the recess and an outlet of the liquid introduction flow path opening opposite to the vertical wall surface are disposed in a first region on a bottom side of the recess that opens on an inner surface of the casing; a second region on the inner surface side of the casing of the recess, which is continuous with the first region, is bent at the boundary with the vertical wall surface, and a bent surface is arranged so as to continue in a direction away from the outlet of the liquid introduction flow path.

2. 2. The screw compressor according to claim 1, wherein the bent surface is bent in a step shape at a boundary portion between the bent surface and the vertical wall surface.

3. 2. The screw compressor according to claim 1, wherein the bent surface is bent in a tapered shape at a boundary portion with the vertical wall surface, and is inclined so as to gradually move in a direction away from the outlet of the liquid introduction passage as it moves from the boundary portion toward the inner surface of the casing.

4. 2. The screw compressor according to claim 1, wherein the liquid introduction passage is arranged at an angle with respect to the vertical wall surface so that the liquid ejected from the outlet collides obliquely with the vertical wall surface from a bottom side of the recess.

5. 2. The screw compressor according to claim 1, wherein the vertical wall surface in the first region is formed parallel to a ridge line of a screw tooth tip of the screw rotor.

6. 2. The screw compressor according to claim 1, wherein the vertical wall surface and the bent surface are disposed at positions opposite to each other in a rotational direction of the screw rotor.

7. The screw compressor according to claim 6, further comprising an inclined surface disposed in the second region at a position opposite to the bent surface and inclined so as to transition from the inner surface of the casing toward a bottom side of the recess as it transitions along the rotation direction of the screw rotor.

8. 8. The screw compressor according to claim 7, wherein the inclined surface has a larger inclination angle with respect to the depth direction of the recess than the bent surface.

9. The screw compressor according to claim 1, characterized in that the vertical wall surface is inclined in a reverse tapered shape so as to gradually transition in a direction approaching an outlet of the liquid introduction passage as it transitions from a bottom side of the recess toward the inner surface of the casing along the depth direction of the recess.

10. 2. The screw compressor according to claim 1, wherein the vertical wall surface has a concavely curved surface portion that is concavely curved in a direction away from the outlet of the liquid introducing channel.

11. 2. The screw compressor according to claim 1, wherein the vertical wall surface has a convexly curved surface portion that is curved convexly in a direction approaching the outlet of the liquid introducing channel.

12. 2. The screw compressor according to claim 1, wherein the liquid supply mechanism is configured separately from the casing.

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