Screw compressor

Abstract

Provided is a screw compressor having a liquid supply mechanism capable of supplying a liquid that has been sufficiently comminuted into tiny droplets to an air compression chamber. This screw compressor 100 comprises a screw rotor 1 and a casing 4 that accommodates the screw rotor, and is provided with a liquid supply mechanism 40 that supplies a liquid 50 into a compression chamber 13 formed in the casing. The liquid supply mechanism 40 has a structure in which a vertical wall surface 422 that follows along the depth direction of the recess and an outlet 441 of a liquid introduction flow passage 44 that opens facing the vertical wall surface are positioned in a first region 42 on the bottom side of a recess 41 opening onto a casing inner surface 4a, and a bent surface 431 that is bent at the boundary with the vertical wall surface and that continues in the direction away from the outlet of the liquid introduction flow passage is positioned in a second region 43 on the casing-inner-surface side of the recess, which is continuous with the first region 42.

Description

Screw Compressor

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

[0002] A screw compressor is a device that compresses gas, such as air. A screw compressor generates compressed gas by meshing two screw-shaped rotors, one male and one female. To increase the gas compression efficiency, a screw compressor is provided with a liquid supply mechanism that injects a liquid, such as oil, into a gas compression chamber formed in a casing that houses the male and female screw rotors. 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 rotor and the casing.

[0003] A conventional technique for supplying liquid into a gas compression chamber is described below. When injecting liquid, one method of breaking the liquid into fine droplets is to utilize the collision energy of the liquid.

[0004] As disclosed in Patent Document 1 below, there is a liquid supply mechanism technology in which a liquid supply nozzle has a pair of injection holes that collide the injected liquid and 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 with each other 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 is provided in a location other than the space of the oil supply hole, on which the liquid collides, 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.

[0006] JP 2021-85389 A1

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

[0008] In the method of injecting liquid from a pair of injection holes and causing them to collide, 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. As a result, the length of time it takes for the liquid to break up from when it leaves the injection holes until 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 down into fine droplets, which poses a problem of insufficient breakup into fine droplets.

[0009] In Patent Document 2, an inclined surface is provided where the liquid collides in a location other than the space of the oil supply hole, and as with Patent Document 1, the liquid comes into contact with the rotor in the form of a liquid film, which poses the problem of not being able to sufficiently break down the liquid into small droplets.

[0010] The present invention has been made in view of the above points, and an object of the present invention is to provide a screw compressor having a liquid supply mechanism that can supply liquid in the form of sufficiently fine droplets to an air compression chamber.

[0011] The screw compressor of the present invention that solves the above-mentioned problems is a screw compressor comprising: a screw rotor; and a casing that houses the screw rotor; and a liquid supply mechanism that supplies liquid into a compression chamber formed within the casing, wherein the liquid supply mechanism has a structure in which a vertical wall surface that follows the depth direction of the recess and an outlet of a liquid introduction flow path that opens opposite the vertical wall surface are arranged in a first region on the bottom side of a recess that opens into the inner surface of the casing; and a bent surface that is bent at a boundary with the vertical wall surface and continues in a direction away from the outlet of the liquid introduction flow path in a second region on the inner surface of the casing of the recess that is continuous with the first region.

[0012] According to the screw compressor of the present invention, the liquid supply mechanism can sufficiently break down the liquid into small droplets and supply them to the air compression chamber. Further features related to the present invention will become apparent from the description of this specification and the accompanying drawings. Furthermore, problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0013] 1 is a diagram showing the configuration of a screw compressor according to a first embodiment of the present invention. It is a cross-sectional view of the screw rotor and the periphery of a liquid supply mechanism taken along line II-II in FIG. 1 . It is a diagram showing the arrangement of the liquid supply mechanism in the screw compressor according to the first embodiment. It is a cross-sectional view showing the configuration of the liquid supply mechanism of the screw compressor according to the first embodiment. It is a diagram explaining a liquid supply method by the liquid supply mechanism of the screw compressor according to the first embodiment. It is a diagram showing the liquid supply mechanism of the screw compressor according to the first embodiment from the direction of arrow VI in FIG. 5 . It is a diagram showing an example of the configuration of one vertical wall surface of the liquid supply mechanism. It is a diagram showing an example of the configuration of one vertical wall surface of the liquid supply mechanism. It is a cross-sectional view showing the configuration of the liquid supply mechanism of the screw compressor according to a second embodiment. It is a diagram explaining a liquid supply method by the liquid supply mechanism of the screw compressor according to the second embodiment. It is a cross-sectional view showing the configuration of the liquid supply mechanism of the screw compressor according to a third embodiment. It is a cross-sectional view showing the configuration of the liquid supply mechanism of the screw compressor according to a fourth embodiment.

[0014] Hereinafter, with reference to the drawings, an embodiment of a liquid supply mechanism for a screw compressor according to the present invention will be described. In each drawing, the same elements are denoted by the same reference numerals, and redundant description will be omitted. It should be noted that the present invention is not limited to the embodiments described below and includes various modifications. For example, the embodiments described below are described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the components. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

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

[0016] As shown in Fig. 1, the 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 has 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 2" is used as a general term for these rotors.

[0017] The screw compressor 100 includes 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 components 7 such as oil seals and mechanical seals. An inlet port 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 via a rotor shaft to a motor 8, which is a rotational drive source. 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, maintaining gaps of several tens to several hundreds of micrometers with 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, causing the compression chamber 13, formed by the tooth grooves of the male rotor 2 and the female rotor 3 and the surrounding male bores 9 and female bores 10, to expand and contract. As a result, gas such as air is drawn 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 outside the screw compressor 100 into the compression chamber 13, the suction side bearing 5, the discharge side bearing 6, and the shaft seal component 7 through a liquid supply hole 16, a suction side bearing liquid supply hole 17, and a discharge side bearing liquid supply hole 18. Discharge air 60 discharged from the discharge port 15 is separated into a gas such as air and a liquid such as lubricating oil by a centrifugal oil separator 61, and the liquid is cooled to an appropriate temperature by a cooler 62 before being used for supply again.

[0021] The screw compressor 100 is provided with a liquid supply mechanism 40 that supplies a liquid such as lubricating oil into the compression chambers 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, 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, as shown in Figure 3.

[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, a liquid supply mechanism 40 is provided on both the male rotor 2 side and the female rotor 3 side, but because these have the same configuration, the following description will only describe the configuration of the liquid supply mechanism 40 provided on the male rotor 2 side, and will omit a description of the configuration of the liquid supply mechanism 40 on the female rotor 3 side.

[0023] The liquid supply mechanism 40 has a recess 41 that opens to the inner surface 4a of the casing. The liquid supply mechanism 40 may be formed integrally with the casing 4, or may be formed separately from the casing 4 in consideration of ease of processing and maintenance. In this embodiment, the recess 41 is formed in a recess main body 411 that is formed 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 that is continuous with the first region 42 and is 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 of the recess bottom surface 421 in the groove width direction along the depth direction of the recess 41. Of the pair of vertical wall surfaces 422, 423, one vertical wall surface 422 is arranged to be located forward in the rotation direction F of the male rotor 2, and the other vertical wall surface 423 is arranged to be located rearward of the one vertical wall surface 422 in the rotation direction F of the male rotor 2. In other words, one vertical wall surface 422 is arranged in a position facing the rotation direction of the screw rotor 1.

[0026] The liquid supply mechanism 40 has a liquid introduction channel 44 for introducing liquid into the recess 41 from outside the casing 4. An outlet 441 of the liquid introduction channel 44 opens in the bottom surface 421 of the recess. The outlet 441 of the liquid introduction channel 44 is positioned so as to open opposite one of the vertical wall surfaces 422. The liquid introduction channel 44 is formed toward the one of the vertical wall surfaces 422, that is, it is provided so as to extend in a direction gradually approaching the one of the vertical wall surfaces 422 as it moves toward the outlet 441. The liquid introduction channel 44 is formed at a predetermined inclination angle θa with respect to the one of the vertical wall surfaces 422 so that liquid ejected from the outlet 441 impinges obliquely on the one of the vertical wall surfaces 422 along the depth direction of the recess 41 from the bottom side of the recess 41 toward the opening side of the recess 41. The inclination angle θa is set to an angle smaller than perpendicular. The base end of the inlet of the liquid introduction channel 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 disposed, which is bent at the boundary with one vertical wall surface 422 and continues in a direction away from the outlet 441 of the liquid introduction 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 with the one vertical wall surface 422. In this embodiment, the bent surface 431 is bent in a vertical step shape at the boundary with the one vertical wall surface 422, and is a surface that is discontinuous with the one vertical wall surface 422. A vertical wall surface 433 is provided at the end of the bent surface 431, which is bent toward the casing inner surface 4a and rises up.

[0028] Furthermore, the second region 43 of the recess 41 is formed with an inclined surface 434 that 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 moves along the rotation direction of the screw rotor 1. The angle θc of the inclined surface 434 is set to an inclination angle that allows gas that is pushed out by the male rotor 2 in the compression chamber 13 and moves along the casing inner surface 4a to flow smoothly into the recess 41.

[0029] Next, a liquid supply method using the liquid supply mechanism 40 will be described with reference to Figures 5 and 6. Figure 5 is a diagram for explaining a liquid supply method using the liquid supply mechanism of the screw compressor according to the first embodiment, and Figure 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 Figure 5.

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

[0031] The thin liquid film 51 moving along the one vertical wall surface 422 in this manner within the first region 42 passes through an edge 432 formed at the boundary between the 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 rather breaks off from the vertical wall surface 422 due to its own inertial force and is released into the air in the second region 43 of the recess 41. The liquid film 51 released into the air breaks up 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. The liquid film 51 is then 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. This improves the cooling of the compressed air in the compression chamber 13 and the sealing of gaps in each section.

[0033] In this embodiment, an inclined surface 434 is formed that 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 that 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 effects, when the liquid is sprayed from the liquid supply mechanism 40, it is possible to achieve sufficient fine droplets, thereby improving the cooling performance of the compressed air and the sealing performance of the gaps in each part.

[0035] According to the screw compressor 100 of this embodiment, the droplets are miniaturized and the total surface area of ​​the droplets is increased, which cools the compressed gas, increasing its density and improving compression efficiency. Furthermore, the droplets are miniaturized and dispersed over a wide area in the air compression chamber, and the liquid adheres uniformly to the gaps between the screw rotors and the gaps between the screw rotors and the casing, thereby reducing gas leakage from the gaps.

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

[0037] 7A is a diagram illustrating an example of the configuration of one vertical wall surface of the liquid supply mechanism, showing the shape of the thin liquid film 51 formed in the cross section taken along line VII-VII in FIG. 5. In this example configuration, the vertical wall surface 422 has a flat surface portion 422A. Therefore, when the liquid 50 collides with the flat surface portion 422A of the vertical wall surface 422, it can quickly spread from the collision point in directions away from each other along the longitudinal direction of the recess 41, forming a thin liquid film 51 and facilitating the formation of fine droplets. Furthermore, the flat surface portion 422A is easy to process, which can reduce the number of steps required to form the vertical wall surface 422.

[0038] FIG. 7B shows another example of the configuration of one vertical wall surface of the liquid supply mechanism, illustrating the shape of the thin liquid film 51 formed in the cross section taken along line VII-VII in FIG. 5 . In the example configuration shown in FIG. 7B , the vertical wall surface 422 has a concave curved surface portion 422B that curves concavely in a direction away from the outlet 441 of the liquid introduction channel 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 curves concavely in a direction perpendicular to the direction of liquid ejection. This increases the force with which the thin liquid film 51 is pressed against the liquid collision surface 33, allowing the liquid film to thin from a position closer to the collision position, resulting in the formation of a more uniform and thinner liquid film. As a result, it is possible to further promote the formation of finer droplets.

[0039] FIG. 7C shows another example of the configuration of one vertical wall surface of the liquid supply mechanism, illustrating the shape of the thin liquid film 51 formed in the cross section taken along line VII-VII in FIG. 5 . In the example configuration shown in FIG. 7C , the vertical wall surface 422 has a convexly curved surface portion 422C that curves convexly in a direction away from the outlet 441 of the liquid introduction channel 44 and protrudes like a hill. The convexly curved surface portion 422C is formed along the longitudinal direction of the recess 41 and has a convexly curved surface shape that is convexly curved 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 area. This allows fine droplets to be dispersed over a wider area from the liquid supply mechanism 40, 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 feature of this embodiment is that the second region 43 of the recess 41 has a bent surface 435 that is inclined with respect to the vertical wall surface 422. The bent surface 435 is bent at the boundary with one of the vertical wall surfaces 422 and has a planar shape that continues in a direction away from the outlet 441 of the liquid introduction channel 44. The bent surface 435 is disposed at a position that faces the rotation direction of the screw rotor 1.

[0042] The bent surface 435 is bent at a predetermined angle θb relative 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, forming 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 film 51 does not move along the bent surface 431 as it enters the second region 43, but instead breaks off from the vertical wall surface 422 due to its own inertial force and is released into the air in the second region 43 of the recess 41. The liquid film 51 released into the air breaks up 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. The liquid film 51 is then 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. This improves the cooling of the compressed air in the compression chamber 13 and the sealing of gaps in each section.

[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 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 recessed portion 41, thereby generating strong disturbances due to the airflow.

[0046] <Third and Fourth Embodiments> Next, screw compressors according to third and fourth embodiments will be described. Figures 10 and 11 are views showing the configuration of a liquid supply mechanism of a screw compressor according to the 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 the perpendicular to the vertical wall surface 422 and larger than 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 (in FIG. 6 , it inclines to the right as it goes up). That is, the vertical wall surface 422 is inclined in an inverse tapered manner so as to gradually move toward the outlet 441 of the liquid introduction channel 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 accelerated from being broken down into fine droplets.

[0049] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as defined 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 including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0050] DESCRIPTION OF SYMBOLS 1...Screw rotor, 4...Casing, 4a...Inner surface of casing, 13...Compression chamber, 40...Liquid supply mechanism, 41...Recess, 42...First region (liquid collision space), 43...Second region (liquid separation space), 44...Liquid introduction flow path, 100...Screw compressor, 421...Bottom surface of recess, 422...Vertical wall surface, 422B...Concave curved surface portion, 422C...Convex curved surface portion, 431, 435...Bent surface, 432...Edge, 441...Outlet, 434...Inclined surface

Claims

1. A screw compressor comprising a screw rotor and a casing that houses the screw rotor, and equipped with a liquid supply mechanism that supplies liquid into a compression chamber formed within the casing, wherein the liquid supply mechanism has a structure in which a vertical wall surface that runs along the depth direction of the recess and an outlet of a liquid introduction flow passage that opens opposite the vertical wall surface are arranged in a first region on the bottom side of a recess that opens into the inner surface of the casing, and a bent surface that is bent at the boundary with the vertical wall surface and continues in a direction away from the outlet of the liquid introduction flow passage in a second region on the inner surface side of the casing of the recess that is continuous with the first region.

2. The screw compressor according to claim 1, wherein said bent surface is formed by being bent in a step shape at the boundary portion with said vertical wall surface.

3. A screw compressor as described in claim 1, characterized in that the bent surface is bent in a tapered manner at the boundary with the vertical wall surface, and is gradually inclined so as to 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. A screw compressor as described in claim 1, characterized in that the liquid introduction passage is arranged at an incline with respect to the vertical wall surface so that liquid sprayed from the outlet collides obliquely with the vertical wall surface from the bottom side of the recess.

5. A screw compressor according to claim 1, wherein said vertical wall surface in said first region is formed parallel to a ridge line of the screw teeth of said screw rotor.

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

7. A screw compressor as described in claim 6, characterized in that it has an inclined surface arranged in a position opposite to the bent surface in the second region and inclined so as to transition from the inner surface of the casing to the bottom side of the recess as it transitions along the rotational direction of the screw rotor.

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

10. A screw compressor according to claim 1, characterized in that the vertical wall surface has a concavely curved surface portion that is curved concavely in a direction away from the outlet of the liquid introduction passage.

11. 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 passage.

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

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