Liquid supply type screw compressor
Patent Information
- Application Number
- JP2023133902
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-08-21
- Publication Date
- 2025-03-06
Smart Images
Figure 2025029344000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a liquid feed type screw compressor that supplies liquid such as oil or water to a working chamber, and more particularly to a liquid feed type screw compressor that discharges compressed gas and liquid in a working chamber through a discharge port. [Background technology]
[0002] A screw compressor includes a pair of screw rotors having helical teeth (tooth grooves) and a casing that houses the two screw rotors in a state of meshing with each other. The screw compressor sucks in and compresses gas by increasing and decreasing the volume of a working chamber formed by the two screw rotors and the inner wall surface of the casing as the two screw rotors rotate. The pair of screw rotors have a discharge side end face at one axial end. A discharge port for discharging compressed gas is formed on the inner wall surface of the casing that faces the discharge side end faces of the two screw rotors. Among screw compressors, there are liquid-feed compressors that supply liquid such as oil or water to the working chamber and liquid-free compressors that do not supply the liquid to the working chamber.
[0003] In a screw compressor, if the opening area of the working chamber to the discharge port of the working chamber disappears before the volume of the working chamber formed by the meshing of both screw rotors becomes zero during the discharge stroke in which the compressed gas in the working chamber is discharged, the compressed gas in the working chamber may be overcompressed, resulting in power loss. In detail, the meshing of both screw rotors periodically forms a crescent-shaped working chamber that is open only in the axial direction at the discharge end surface and whose volume decreases with the rotation of the screw rotor. The working chamber is in a state where it is partially open to the discharge port, and the opening area to the discharge port gradually narrows with the rotation of both screw rotors. If compressed gas remains in the working chamber when the opening area to the discharge port of this working chamber disappears, the compressed gas in the working chamber cannot be discharged through the discharge port and is overcompressed. As a result, the torque driving both screw rotors increases, resulting in power loss in the screw compressor.
[0004] As a solution to this problem, for example, a screw compressor has been proposed as described in Patent Document 1. In this screw compressor, a groove is provided adjacent to the discharge port of the casing, which is connected to the discharge port at the timing when the volume of the compression working space (working chamber) formed by both rotors and the casing as a pair of male and female screw rotors rotates becomes almost zero. [Prior art documents] [Patent documents]
[0005] [Patent Document 1] JP 2010-275931 A Summary of the Invention [Problem to be solved by the invention]
[0006] The screw compressor described in Patent Document 1 is an oil-free type. Even if the configuration of this oil-free type screw compressor (groove provided adjacent to the discharge port of the casing) is applied to an oil-fed screw compressor, the effect of suppressing power loss due to overcompression in the discharge stroke may be insufficient. Specifically, in a liquid-fed screw compressor, power loss may occur due to liquid being caught by both screw rotors in the discharge stroke. The working chamber in the discharge stroke discharges both compressed gas and liquid when the volume decreases with the rotation of the screw rotor. However, since the specific gravity of compressed gas is smaller than that of liquid (e.g., oil), the compressed gas tends to be discharged before the liquid. Therefore, in the early to middle stages of the discharge stroke, a large ratio of compressed gas to liquid is discharged. As a result, in the later stages of the discharge stroke, the ratio of compressed gas remaining in the working chamber to liquid becomes smaller. In the final stage of the discharge stroke (the period when the volume approaches zero), almost only liquid remains in the working chamber. For this reason, even if the liquid remaining in the working chamber in the latter part of the discharge stroke is discharged into a groove provided adjacent to the discharge port as in the screw compressor described in Patent Document 1, it may remain in the groove, which is a narrower space than the discharge port. For this reason, the liquid in the working chamber in the final part of the discharge stroke is not discharged into the groove but remains in the working chamber, causing jamming between the two screw rotors. As a result, the liquid in the working chamber is overcompressed, resulting in power loss in the screw compressor.
[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 type screw compressor that can suppress over-compression of the liquid in the working chamber during the discharge stroke. [Means for solving the problem]
[0008] The present application includes a plurality of means for solving the above-mentioned problems. For example, a liquid-feed screw compressor includes a male rotor having a discharge end face on one axial side and rotatable around a first axis, a female rotor having a discharge end face on one axial side and rotatable around a second axis parallel to the first axis, a bearing for rotatably supporting the one axial side of the female rotor, and a casing having an accommodation chamber for rotatably accommodating the male rotor and the female rotor in a state of meshing with each other and a bearing chamber in which the bearing is disposed, the casing has a discharge port formed on a discharge side inner wall surface of the accommodation chamber facing the discharge side end face of the male rotor and the discharge side end face of the female rotor, the discharge port being located in an area on one side away from a reference line which is a straight line passing through the first axis and the second axis. the female rotor has a main opening formed on the male rotor and defined based on a tooth profile on the discharge side end face of the male rotor and a tooth profile on the discharge side end face of the female rotor, and a groove portion connected to an end of the main opening on the reference line side and close to the second axis and extending from the main opening to the reference line side, the female rotor has a discharge hole having a first opening on one side that opens onto the discharge side end face of the female rotor and a second opening on the other side that communicates with the bearing chamber, the first opening of the discharge hole is positioned such that its circumferential position of the female rotor corresponds to the bottom of the teeth on the discharge side end face of the female rotor, and is configured to periodically face the groove portion without always facing the main opening in the discharge port. Effect of the Invention
[0009] According to one embodiment of the present invention, the second opening on the other side of the female rotor's discharge hole is connected to the bearing chamber, and the first opening on one side is configured to periodically face the groove of the discharge port, so that liquid in the working chamber during the discharge stroke is sucked from the groove of the discharge port through the female rotor's discharge hole into the bearing chamber, which has a relatively lower pressure than the discharge port, thereby making it possible to suppress overcompression due to liquid getting caught in the working chamber during the discharge stroke. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]
[0010] [Figure 1] FIG. 1 is a vertical sectional view showing a liquid feed type screw compressor according to a first embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view of the liquid feed screw compressor according to the first embodiment, taken along the line II-II in FIG. 1. [Diagram 3] FIG. 2 is a perspective view showing a discharge side flow path formed in a discharge side casing of the liquid feed type screw compressor according to the first embodiment shown in FIG. 1 and a discharge port on a wall surface of the discharge side casing, and an enlarged view showing an area indicated by the symbol P in the perspective view in an enlarged state. [Figure 4] FIG. 2 is a vertical sectional view of a female rotor in the liquid feed screw compressor according to the first embodiment shown in FIG. [Diagram 5] FIG. 5 is a side view of the female rotor of the liquid feed screw compressor according to the first embodiment shown in FIG. 4, as viewed from an arrow V (axial discharge side). [Figure 6] FIG. 2 is an explanatory diagram showing the positional relationship between a discharge port of a casing and a discharge hole opening on the discharge side end face of a female rotor in the liquid feed type screw compressor according to the first embodiment. [Figure 7] FIG. 4 is a diagram for explaining entrapment of liquid during the discharge stroke in a liquid feed type screw compressor as a comparative example compared to the liquid feed type screw compressor according to the first embodiment. [Figure 8] FIG. 4 is a diagram for explaining the function and effect of the discharge stroke of the liquid feed screw compressor according to the first embodiment. [Figure 9] FIG. 6 is a vertical sectional view of a female rotor in a liquid feed type screw compressor according to a second embodiment of the present invention. [Figure 10] 10 is a side view of a female rotor of the liquid feed type screw compressor according to the second embodiment shown in FIG. 9, as viewed from an arrow X (axial discharge side). FIG. [Figure 11] FIG. 11 is an explanatory view showing the positional relationship between a discharge port of a casing and a discharge hole opening on the discharge side end face of a female rotor in a liquid feed type screw compressor according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a liquid feed type screw compressor according to the present invention will be described by way of example with reference to the drawings.
[0012] [First embodiment] The configuration of a liquid feed type screw compressor according to a first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a vertical sectional view showing a liquid feed type screw compressor according to a first embodiment of the present invention. Fig. 2 is a sectional view of the liquid feed type screw compressor according to the first embodiment as seen from the arrow II-II shown in Fig. 1. In Figs. 1 and 2, the left side is the suction side of the screw compressor, and the right side is the discharge side.
[0013] 1 and 2, a liquid-feeding screw compressor (hereinafter referred to as a screw compressor) 1 includes a male rotor 2 and a female rotor 3 as a pair of screw rotors that rotate while meshing with each other, and a casing 4 that houses the male rotor 2 and the female rotor 3 inside so that they can rotate while meshing with each other. The male rotor 2 and the female rotor 3 are rotatable about an axis A1 and an axis A2, respectively, and the male rotor 2 and the female rotor 3 are arranged so that the axes A1 and A2 are parallel to each other. The male rotor 2 is rotatably supported at both ends in the axial direction (left and right direction in Figs. 1 and 2) by a suction side bearing 5 and a discharge side bearing 6, respectively. The female rotor 3 is rotatably supported at both ends in the axial direction by a suction side bearing 7 and a discharge side bearing 8, respectively.
[0014] The male rotor 2 is composed of a rotor tooth portion 21 having a plurality of helical male 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 perpendicular to the axial direction (axis A1) at one axial end (left end in Figs. 1 and 2) and the other axial end (right end in Figs. 1 and 2), respectively. Tooth grooves are formed between the male teeth 21a of the rotor tooth portion 21. The suction side shaft portion 22 is configured to extend, for example, outside the casing 4, and is connected to a rotation drive source such as an electric motor (not shown). A shaft seal member 15 is arranged on the suction side shaft portion 22 of the male rotor 2 to seal a gap between the suction side shaft portion 22 and the casing 4. The shaft seal member 15 is, for example, an oil seal or a mechanical seal.
[0015] The female rotor 3 is composed of a rotor tooth portion 31 having a plurality of helical female teeth (lobes) 31a, and a suction side shaft portion 32 and a discharge side shaft portion 33 provided on both axial end portions 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 perpendicular to the axial direction (axis A2) 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 female teeth 31a of the rotor tooth portion 31. The screw compressor 1 of this embodiment is characterized by the rotor tooth portion 31 and the discharge side shaft portion 33 of the female rotor 3. The detailed structures of the rotor tooth portion 31 and the discharge side shaft portion 33 of the female rotor 3 will be described later.
[0016] The casing 4 includes a main casing 41 and a discharge-side casing 42 attached to the discharge side (right side in Figs. 1 and 2) of the main casing 41. An accommodation chamber 45 is formed inside the casing 4 to accommodate the rotor teeth 21 of the male rotor 2 and the rotor teeth 31 of the female rotor 3 in a state of meshing with each other. The accommodation chamber 45 is formed by closing the opening on one axial side (right side in Figs. 1 and 2) of two partially overlapping cylindrical spaces (bores) formed in the main casing 41 with the discharge-side casing 42. The wall surfaces forming the accommodating chamber 45 are composed of a first inner circumferential surface 46 having an approximately cylindrical shape covering the radial outside of the rotor tooth portion 21 of the male rotor 2, a second inner circumferential surface 47 having an approximately cylindrical shape covering the radial outside of the rotor tooth portion 31 of the female rotor 3, a suction side inner wall surface 48 on one axial side (left side in Figures 1 and 2) 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 49 on the other axial side (right side in Figures 1 and 2) facing the discharge side end faces 21c, 31c of the rotor tooth portions 21, 31 of both the male and female rotors 2, 3. Multiple working chambers C are formed by the rotor teeth 21, 31 of the male and female rotors 2, 3 and the inner wall surface of the casing 4 surrounding them (the first inner surface 46, the second inner surface 47, the suction side inner wall surface 48, and the discharge side inner wall surface 49 of the accommodating chamber 45).
[0017] The suction side end of the main casing 41 (the axial end opposite the opening) is provided with a suction side bearing chamber 51 in which the suction side bearing 5 on the male rotor 2 side is disposed, and a suction side bearing chamber 52 in which the suction side bearing 7 on the female rotor side is disposed. The suction side bearing chamber 51 and the suction side bearing chamber 52 are in communication with each other. The two suction side bearing chambers 51, 52 are separated from the accommodation chamber 45 by a suction side partition wall 53. A suction side cover 43 is attached to the main casing 41 so as to close the openings of the two suction side bearing chambers 51, 52. The suction side bearing chambers 51, 52 are at approximately atmospheric pressure.
[0018] The discharge side casing 42 is provided with a discharge side bearing chamber 55 in which the discharge side bearing 6 of the male rotor 2 is disposed, and a discharge side bearing chamber 56 in which the discharge side bearing 8 for the female rotor 3 is disposed. The discharge side bearing chamber 55 and the discharge side bearing chamber 56 are mutually connected. The two discharge side bearing chambers 55, 56 are configured to be separated from the accommodation chamber 45 by a discharge side partition wall 57. The discharge side cover 44 is attached to the discharge side casing 42 so as to close the openings of the two discharge side bearing chambers 55, 56. The discharge side bearing chambers 55, 56 are also at approximately atmospheric pressure.
[0019] 2, the casing 4 is provided with a suction passage 61 for sucking gas into the working chamber C. The suction passage 61 connects the outside of the casing 4 with the accommodation chamber 45 (working chamber C).
[0020] The casing 4 is provided with a discharge passage 62 for discharging compressed gas from the working chamber C to the outside of the casing 4. The discharge passage 62 connects the accommodation chamber 45 (working chamber C) with the outside of the casing 4. The discharge passage 62 has a discharge port 63 formed on the discharge side inner wall surface 49 of the casing 4. The screw compressor 1 of this embodiment is also characterized by the structure of the discharge port 63. The structure of the discharge port 63 will be described in detail later.
[0021] The casing 4 is provided with a liquid supply passage 59 for supplying liquid supplied from outside (supply source) of the screw compressor 1 to the working chamber C. The liquid supply passage 59 is open, for example, to a region of the inner wall surface of the accommodation chamber 45 where the working chamber C undergoes a compression stroke. The liquid is supplied for the purpose of cooling the compressed gas in the working chamber C and sealing the gaps between the male and female rotors 2, 3 and the casing. Similarly, liquid is also supplied from the supply source to the suction side bearing chambers 51, 52 and the discharge side bearing chambers 55, 56 to lubricate the suction side bearings 5, 7 and the discharge side bearings 6, 8.
[0022] Next, the discharge port of the discharge flow passage formed in the casing in the liquid feed type screw compressor of the first embodiment will be described with reference to Fig. 3. Fig. 3 is a perspective view showing the discharge side flow passage formed in the discharge side casing of the liquid feed type screw compressor according to the first embodiment shown in Fig. 1 and the discharge port on the wall surface of the discharge side casing, and an enlarged view showing an area indicated by the symbol P in the perspective view in an enlarged state.
[0023] 3, a discharge flow passage 62 formed in the casing 4 (discharge-side casing 42) has a discharge port 63 that opens in the discharge-side inner wall surface 49 of the casing 4. The discharge port 63 is formed in an area on one side (lower side in FIG. 3) of a reference line L that passes through the axis A1 of the male rotor 2 and the axis A2 of the female rotor 3.
[0024] The discharge port 63 has a main opening 64 formed in an area on one side away from the reference line L, and an opening of a groove portion 65 connected to the main opening 64. The main opening 64 is determined based on the tooth profile of the discharge end face 21c of the male rotor 2 and the tooth profile of the discharge end face 31c of the female rotor 3, and is a portion where the working chamber C (see, for example, the upper and middle figures in FIG. 8 described later) is in direct communication from the start of the discharge stroke to a certain stage in the latter half. The groove portion 65 is basically interposed between the main opening 64 and the working chamber C (see, for example, the lower figure in FIG. 8 described later) whose volume has been reduced in the final stage of the discharge stroke, and maintains the communication relationship therebetween.
[0025] Specifically, the contour of the main opening 64 of the discharge port 63 includes, for example, a first contour line 71 and a second contour line 72 that form a pair of side edges of a tongue-shaped protrusion 49a that can close the working chamber whose volume increases as the male rotor 2 and the female rotor 3 rotate, of the two working chambers that are periodically formed by the meshing of the discharge side end faces 21c, 31c of the male and female rotors 2, 3 and open only in the axial direction. Further, there are included a third contour line 73 extending along a part of the curve obtained by projecting the tooth bottom circle (not shown) of the female rotor 3 onto the discharge side inner wall surface 49 of the casing 4, a fourth contour line 74 extending along a curve obtained by projecting the tooth surface shape (see FIG. 6 described later) of the discharge side end face 31c of the female rotor 3 onto the discharge side inner wall surface 49 of the casing 4, a fifth contour line 75 extending along a part of the curve obtained by projecting the tooth bottom circle (not shown) of the male rotor 2 onto the discharge side inner wall surface 49 of the casing 4, and a sixth contour line 76 extending along the curve obtained by projecting the tooth surface shape (see FIG. 6 described later) of the discharge side end face 21c of the male rotor 2 onto the discharge side inner wall surface 49 of the casing 4. The tongue-shaped protruding portion 49a has a shape that protrudes inward of the discharge port 63 in a direction away from the reference line L.
[0026] The groove portion 65 is connected to the end of the main opening 64 on the reference line L side and to a portion close to the axis A2 of the female rotor 3, and is configured to extend from the main opening 64 to the reference line L side. Specifically, the groove portion 65 is, for example, connected to the end of the main opening 64 on the reference line L side and to a portion close to the axis A2 of the female rotor 3, and is configured with a groove body 66 extending from the main opening 64 to the reference line L side, and a recess 67 connected to a portion (for example, a tip portion) of the groove body 66 close to the axis A2 of the female rotor 3. In detail, the groove body 66 is configured to extend from the connection portion between the first contour line 71 and the third contour line 73 toward the reference line L. The groove body 66 ensures an indirect communication state between the working chamber Cd (for example, see the lower diagram of FIG. 8 described later) whose volume has been reduced in the final stage of the discharge stroke and the main opening 64. That is, the groove body 66 is interposed between the working chamber Cd in the final stage of the discharge stroke and the main opening 64 to communicate therebetween. If the groove width of the groove body 66 is made too large, it may communicate the working chamber in the discharge stroke with the working chamber in the suction stroke, so there is a restriction on the groove width. The recess 67 periodically provides direct communication with a discharge hole 35 (first opening 36a) of the female rotor 3, which will be described later. That is, the recess 67 is interposed between the groove body 66 of the discharge port 63 and the discharge hole 35 of the female rotor 3, which will be described later, to periodically ensure an indirect communication state therebetween.
[0027] Next, the characteristic features of the female rotor in the liquid feed type screw compressor according to the first embodiment will be described with reference to Figs. 4 to 6. Fig. 4 is a longitudinal sectional view of the female rotor in the liquid feed type screw compressor according to the first embodiment shown in Fig. 1. Fig. 5 is a side view of the female rotor of the liquid feed type screw compressor according to the first embodiment shown in Fig. 4, seen from the arrow V (axial discharge side). Fig. 6 is an explanatory diagram showing the positional relationship between the discharge port of the casing and the discharge hole opening on the discharge side end face of the female rotor in the liquid feed type screw compressor according to the first embodiment. In Fig. 6, the shapes of the structures on the discharge side end face of the male rotor and the discharge side end face of the female rotor projected onto the discharge side inner wall face of the casing are shown by dashed lines. In Fig. 6, the thick arrows indicate the rotation directions of the male rotor and the female rotor.
[0028] 4 and 5, the female rotor 3 has discharge holes 35 that periodically communicate with the recesses 67 of the grooves 65 in the discharge port 63 shown in Fig. 3 and that always communicate with the discharge-side bearing chamber 56 (which is lower in pressure than the discharge pressure and is usually approximately atmospheric pressure) on the female rotor 3 side shown in Fig. 1. As shown in Fig. 4, the discharge holes 35 are composed of a first hole portion 36 provided in the rotor tooth portion 31 and having a first opening portion 36a that opens onto the discharge-side end face 31c, and a second hole portion 37 provided in the discharge-side shaft portion 33 and having a second opening portion 37a that communicates with the discharge-side bearing chamber 56 (see Fig. 1). As shown in Fig. 5, the female rotor 3 has discharge holes 35 in the same number as the number of female teeth 31a of the female rotor 3.
[0029] As shown in FIG. 5, the first opening 36a of the first hole 36 is configured so that its radial position corresponds to the outer circumferential edge of the discharge-side shaft portion 33. That is, the first opening 36a opens at the radially innermost position on the discharge-side end face 31c. The first opening 36a is arranged so that its circumferential position corresponds to the tooth bottom, not the tooth tip, on the discharge-side end face 31c of the female rotor 3. As shown in FIG. 4, the first hole 36 extends from the discharge-side end face 31c to the rotor tooth portion 31 so as to be inclined toward the radial inside with respect to the axis A2. The first hole 36 is formed in the same number as the number of female teeth 31a of the female rotor 3.
[0030] The second opening 37a of the second hole portion 37 is open on the axial end surface 33a of the discharge side shaft portion 33, as shown in FIG. 5, for example. The axial end surface 33a of the discharge side shaft portion 33 is a portion facing the discharge side bearing 8 on the female rotor 3 side shown in FIG. 1, and is exposed to the discharge side bearing chamber 56. The second opening 37a is arranged so that its circumferential position corresponds to the tooth bottom, not the tooth tip, on the discharge side end surface 31c of the female rotor 3, similarly to the first opening 36a. The second hole portion 37 is formed so as to extend from the axial end surface 33a facing the discharge side bearing 8 to the end position of the first hole portion 36 in parallel to the axis A2, as shown in FIG. 4. The second hole portions 37 are formed in the same number as the number of female teeth 31a of the female rotor 3.
[0031] As shown in Fig. 6, each discharge hole 35 of the female rotor 3 is configured such that, when viewed from the direction of the axis A2 of the female rotor 3, each first opening 36a on the discharge side end face 31c of the female rotor 3 overlaps only with the recessed portion 67 of the groove portion 65 of the discharge port 63 of the discharge side inner wall surface 49 of the casing 4 every rotation of the female rotor 3 (periodically). In other words, each discharge hole 35 of the female rotor 3 and the discharge port 63 of the casing 4 are configured to periodically communicate with each other by the first opening 36a of each discharge hole 35 and the recessed portion 67 of the groove portion 65 periodically facing each other. Conversely, each discharge hole 35 of the female rotor 3 and the discharge port 63 of the casing 4 are configured such that the first opening 36a of each discharge hole 35 and the main opening 64 of the discharge port 63 are always avoided from facing each other. Further, each discharge hole 35 of the female rotor 3 and the discharge port 63 are configured so as to always avoid opposing the first opening 36a of each discharge hole 35 and the groove body 66 of the groove portion 65. In other words, the groove body 66 is formed to a size such that opposing the first opening 36a of each discharge hole 35 is always avoided.
[0032] Next, the operation and effect of the liquid feed type screw compressor according to the first embodiment will be described by comparing it with a liquid feed type screw compressor of a comparative example. First, the configuration and operation of the liquid feed type screw compressor of the comparative example will be described with reference to FIG. 7. FIG. 7 is a diagram for explaining the entrapment of liquid during the discharge stroke in the liquid feed type screw compressor of the comparative example compared to the liquid feed type screw compressor of the first embodiment. In FIG. 7, the shapes of the discharge side end faces of both the male and female rotors projected onto the discharge side inner wall surface of the casing are shown by dashed lines. Also, the thick arrows indicate the rotation directions of both rotors. In FIG. 7, the same reference numerals as those in FIG. 1 to FIG. 6 indicate similar parts, and therefore detailed description thereof will be omitted.
[0033] In FIG. 7, the screw compressor 100 of the comparative example has a discharge port 163 on the discharge side inner wall surface 49 of the casing 4. The discharge port 163 includes a structural portion 64 similar to the main opening 64 (see FIG. 6) in the discharge port 63 of the screw compressor 1 according to the first embodiment. Furthermore, the discharge port 163 of the screw compressor 100 of the comparative example includes a groove portion 165 having only a structure similar to the groove body 66 of the groove portion 65 of the discharge port 63 of the screw compressor 1 according to the first embodiment. However, the discharge port 163 of the liquid-feeding screw compressor 100 of the comparative example does not include a structural portion equivalent to the recessed portion 67 (see FIG. 6) of the groove portion 65 of the discharge port 63 in the screw compressor 1 according to the first embodiment.
[0034] Moreover, the female rotor 103 of the screw compressor 100 of the comparative example does not have the discharge hole 35 (see FIGS. 4 and 6) of the female rotor 3 in the screw compressor 1 according to the first embodiment. That is, the screw compressor 100 of the comparative example is configured not to include the first opening 36a of the discharge hole 35 (see FIGS. 5 and 6) on the discharge side end face 31c of the female rotor 103.
[0035] In the comparative screw compressor 100, the female rotor 103 is rotationally driven by driving the male rotor 2. As a result, the working chamber C increases in volume with the rotation of both the male and female rotors 2, 103, sucking in gas through the suction passage 61 (see FIG. 2), and compresses the gas to a predetermined pressure by reducing its volume. In the comparative liquid-supply type screw compressor 100, liquid is supplied to the working chamber from the outside through the liquid supply passage 59 (see FIG. 2) of the casing 4. Therefore, compressed gas and liquid are mixed in the working chamber.
[0036] When each working chamber communicates with the discharge port 163 as the male and female rotors 2, 103 rotate, a discharge stroke is started in which the compressed gas in the working chamber is discharged to the discharge passage 62 through the discharge port 163. The working chamber Cd in the discharge stroke has a communication region D with a relatively large area with respect to the main opening 64 of the discharge port 163 at a relatively early stage of the discharge stroke as shown in the upper diagram of FIG. 7. Therefore, the compressed gas and liquid in the working chamber Cd are discharged to the discharge passage 62 through the main opening 64 of the discharge port 163.
[0037] The volume of the working chamber Cd during the discharge stroke gradually decreases as the discharge stroke progresses with the rotation of the male and female rotors 2, 103. For example, in the working chamber Cd during the discharge stroke shown in the middle diagram of Fig. 7, the communication area D with respect to the discharge port 163 is relatively smaller than that in the upper diagram of Fig. 7, but the area of the communication area D with respect to the main opening 64 of the discharge port 163 is sufficiently secured. Therefore, the compressed gas and liquid in the working chamber Cd are discharged to the discharge flow passage 62 through the main opening 64 of the discharge port 163.
[0038] As described above, when the discharge stroke of the working chamber Cd progresses, the compressed gas tends to be discharged before the liquid. Since the compressed gas has a smaller specific gravity than the liquid, the gas with a relatively smaller inertia is discharged first, followed by the liquid with a relatively larger inertia. For this reason, in the working chamber Cd during the discharge stroke shown in the upper and middle diagrams of FIG. 7, a large proportion of the compressed gas is discharged relative to the liquid. As a result, in the latter part of the discharge stroke, the proportion of the compressed gas remaining in the working chamber Cd relative to the liquid is small, and mainly the liquid is discharged from the working chamber Cd.
[0039] In the final stage of the discharge stroke (period when the volume approaches zero), the working chamber Cd moves to the groove 165 where the communication area D to the discharge port 163 is out of the main opening 64, as shown in the lower diagram of FIG. 7. In the working chamber Cd where the communication area D to the discharge port 163 is located at the groove 165, the compressed gas has already been discharged and only liquid remains. Since the groove 165 of the discharge port 163 is an extremely small area (space) relative to the main opening 64, the liquid discharged from the working chamber Cd to the groove 165 may not flow down to the discharge flow passage 62 and may remain in the groove 165 due to factors such as viscosity. Therefore, the liquid in the working chamber Cd cannot be discharged to the groove 165 due to the resistance of the liquid remaining in the groove 165, while the volume of the working chamber Cd is reduced, causing the male rotor 2 and the female rotor 103 to bite the liquid, resulting in overcompression, in which the pressure in the working chamber Cd rises rapidly. This results in a power loss in the screw compressor.
[0040] Next, the operation and effect of the liquid feed type screw compressor according to the first embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram for explaining the operation and effect of the liquid feed type screw compressor according to the first embodiment in the discharge stroke. In Fig. 8, the shapes of the structures on the discharge side end faces of the male rotor and the female rotor projected onto the discharge side inner wall surface of the casing are shown by dashed lines. In Fig. 8, the thick arrows indicate the rotation directions of the male rotor and the female rotor. The upper, middle, and lower views of Fig. 8 respectively show the same rotation angles of both screw rotors as those shown in the upper, middle, and lower views of Fig. 7.
[0041] In the screw compressor 1 according to this embodiment, the groove 65 connected to the main opening 64 in the discharge port 63 of the casing 4 has a groove body 66 that ensures an indirect communication state between the working chamber Cd in the final stage of the discharge stroke (the stage where the volume approaches 0) and the main opening 64, and also has a recess 67 connected to the tip of the groove body 66 and to a portion on the discharge-side shaft portion 33 side of the female rotor 3. This adds a volume to the groove body 66, which has an extremely small volume compared to the main opening 64. Furthermore, the female rotor 3 has a discharge hole 35 that periodically communicates with the recess 67 of the groove 65 in the discharge port 63 and always communicates with the discharge-side bearing chamber 56 on the female rotor 3 side.
[0042] As shown in the upper diagram of Fig. 8, the working chamber Cd at a relatively early stage of the discharge stroke has a communication region D with a relatively large area with respect to the main opening 64 of the discharge port 63, as in the case of the upper diagram of Fig. 7. At this time, the groove portion 65 (groove body 66 and recessed portion 67) of the discharge port 63 does not face the first opening 36a of the discharge hole 35 of the female rotor 3, and communication with the discharge hole 35 is blocked. Therefore, the compressed gas and liquid in the working chamber Cd are discharged into the discharge flow path 62 through the main opening 64 of the discharge port 63.
[0043] 8, the communication area D with respect to the discharge port 63 is relatively smaller than that in the upper diagram of FIG. 8, but the area of the communication area D with respect to the main opening 64 of the discharge port 63 is sufficiently secured. At this time, the groove 65 (groove body 66 and recess 67) of the discharge port 63 does not face the first opening 36a of the discharge hole 35 of the female rotor 3, and communication with the discharge hole 35 is blocked. Therefore, the compressed gas and liquid in the working chamber Cd are discharged to the discharge flow passage 62 through the main opening 64 of the discharge port 63.
[0044] When the discharge stroke of the working chamber Cd progresses in this manner, the compressed gas tends to be discharged before the liquid, as in the comparative screw compressor 100. For this reason, in the working chamber Cd during the discharge stroke shown in the upper and middle diagrams of Fig. 8, a large ratio of compressed gas to liquid is discharged. As a result, in the latter part of the discharge stroke, the ratio of compressed gas remaining in the working chamber Cd to liquid is small, and mainly liquid is discharged from the working chamber Cd.
[0045] In the working chamber Cd in the final stage of the discharge stroke (the period when the volume approaches zero), for example, as shown in the lower diagram of Fig. 8, the communication region D for the discharge port 63 moves to the groove body 66 of the groove portion 65 away from the main opening 64. In the working chamber Cd in which the communication region D for the discharge port 63 is located at the position of the groove body 66 of the groove portion 65, the compressed gas has already been discharged and almost only liquid remains, as in the case of the screw compressor 100 of the comparative example.
[0046] At this time, in this embodiment, the recess 67 of the groove 65 of the discharge port 63 faces the first opening 36a of the discharge hole 35 of the female rotor 3. That is, the groove body 66 of the groove 65 of the discharge port 63 is in communication with the discharge hole 35 of the female rotor 3 via the recess 67. On the other hand, the second opening 37a of the discharge hole 35 is always in communication with the discharge-side bearing chamber 56, which has a lower pressure than the discharge flow path 62.
[0047] As a result, when the liquid in the working chamber Cd, in which the communication region D for the discharge port 63 is located in the groove body 66 of the groove 65, is discharged to the groove body 66 side of the groove 65, it is sucked into the discharge hole 35 through the recess 67 of the groove 65 via the first opening 36a and finally discharged to the discharge-side bearing chamber 56. For this reason, in the final stage of the discharge stroke (the period when the volume approaches zero), as in the case of the screw compressor 100 of the comparative example, it is possible to prevent overcompression, in which the liquid in the working chamber Cd cannot be discharged to the groove body 66 due to the liquid remaining in the groove body 66 of the discharge port 63, and the pressure in the working chamber Cd rises suddenly. Therefore, there is no power loss of the screw compressor due to such overcompression. Furthermore, the capacity of the receiving portion for the liquid discharged from the working chamber Cd is increased by the volume of the recess 67 from the volume of the groove body 66, so that the flow resistance of the discharged liquid is reduced.
[0048] As described above, the screw compressor 1 according to the first embodiment includes the male rotor 2 having the discharge side end face 21c on one axial side and rotatable around the first axis A1, the female rotor 3 having the discharge side end face 31c on one axial side and rotatable around the second axis A2 parallel to the first axis A1, the discharge side bearing 8 (bearing) rotatably supporting one axial side of the female rotor 3, and the casing 4 having the accommodation chamber 45 that rotatably accommodates the male rotor 2 and the female rotor 3 in a mutually meshed state and the discharge side bearing chamber 56 (bearing chamber) in which the discharge side bearing 8 (bearing) is arranged. The casing 4 has a discharge port 63 formed on the discharge side inner wall surface 49 of the accommodation chamber 45 that faces the discharge side end face 21c of the male rotor 2 and the discharge side end face 31c of the female rotor 3. The discharge port 63 is formed in an area on one side away from the reference line L, which is a straight line passing through the first axis A1 and the second axis A2, and has a main opening 64 defined based on the tooth profile of the discharge side end face 21c of the male rotor 2 and the tooth profile of the discharge side end face 31c of the female rotor 3, and a groove portion 65 connected to an end of the main opening 64 on the reference line L side and close to the second axis A2, and extending from the main opening 64 to the reference line L side. The female rotor 3 has a discharge hole 35 whose first opening 36a on one side opens onto the discharge side end face 31c of the female rotor 3 and whose second opening 37a on the other side communicates with the discharge side bearing chamber 56 (bearing chamber). The first opening 36a of the discharge hole 35 is arranged so that the position in the circumferential direction of the female rotor 3 corresponds to the bottom of the teeth on the discharge side end face 31c of the female rotor 3, and is configured to periodically face the groove portion 65 without always facing the main opening 64 in the discharge port 63.
[0049] According to this configuration, by configuring the discharge hole 35 so that the second opening 37a on the other side of the discharge hole 35 of the female rotor 3 communicates with the discharge-side bearing chamber 56 (bearing chamber) and the first opening 36a on one side periodically faces the groove 65 of the discharge port 63, the liquid in the working chamber Cd during the discharge stroke is sucked from the groove 65 of the discharge port 63 through the discharge hole 35 of the female rotor 3 into the discharge-side bearing chamber 56 (bearing chamber), which has a relatively lower pressure than the discharge port 63. Therefore, over-compression due to liquid entrapment in the working chamber Cd during the discharge stroke can be suppressed.
[0050] In addition, in this embodiment, the groove portion 65 of the discharge port 63 has a groove body 66 that extends from the main opening 64 toward the reference line L and is formed to a size such that it always avoids opposing the first opening 36a of the discharge hole 35, and a recess 67 that is connected to a portion of the groove body 66 closer to the second axis A2 and periodically faces the first opening 36a of the discharge hole 35.
[0051] With this configuration, even if the size of the groove body 66 of the discharge port 63 is limited, it is possible to periodically face the recess 67 connected to a portion of the groove body 66 to the first opening 36a of the discharge hole 35 of the female rotor 3.
[0052] Moreover, in the female rotor 3 of the screw compressor 1 according to this embodiment, the discharge holes 35 have the first openings 36a the number of which is the same as the number of teeth of the female rotor 3.
[0053] According to this configuration, it is possible to prevent overcompression due to liquid entrapment in all of the working chambers of the multiple discharge strokes caused by the meshing of the male rotor 2 and the female rotor 3 on the discharge side end faces 21c, 31c.
[0054] In the present embodiment, the female rotor 3 has a plurality of discharge holes 35, and each of the discharge holes 35 has one first opening 36a and one second opening 37a.
[0055] According to this configuration, the discharge hole 35 has a simple structure.
[0056] [Second embodiment] Next, a liquid feed type screw compressor according to a second embodiment of the present invention will be described with reference to Figs. 9 and 10. Fig. 9 is a vertical sectional view of a female rotor in a liquid feed type screw compressor according to the second embodiment. Fig. 10 is a side view of the female rotor of the liquid feed type screw compressor according to the second embodiment shown in Fig. 9, as viewed from an arrow X (axial discharge side). In Figs. 9 and 10, the same reference numerals as those in Figs. 1 to 8 denote similar parts, and detailed description thereof will be omitted.
[0057] The screw compressor of the second embodiment shown in Figures 9 and 10 differs from the first embodiment (see Figures 4 and 5) in the configuration of the discharge hole 35A of the female rotor 3A. The other configurations of the screw compressor of the second embodiment are the same as those of the first embodiment.
[0058] Specifically, the discharge hole 35A of the female rotor 3A is configured to periodically communicate with the recess 67 of the groove 65 in the discharge port 63 of the casing 4 shown in Fig. 3, and to always communicate with the discharge side bearing chamber 56 shown in Fig. 1 on the female rotor 3A side. The discharge hole 35A is provided in the rotor tooth portion 31 and is composed of a first hole portion 36A having a first opening portion 36a on the discharge side end face 31c, and a second hole portion 37A provided in the discharge side shaft portion 33 and having a second opening portion 37b that opens into the discharge side bearing chamber 56 (see Fig. 1). The first hole portion 36A has a structure similar to that of the first embodiment, while the second hole portion 37A has a structure different from that of the first embodiment.
[0059] The first opening 36a of the first hole portion 36A is configured so that its radial position corresponds to the position of the outer circumferential edge of the discharge-side shaft portion 33, as in the first embodiment. That is, the first opening 36a opens at the radially innermost position on the discharge-side end face 31c. The first opening 36a is arranged so that its circumferential position corresponds to the tooth bottom portion, not the tooth tip portion, of the rotor tooth portion 31. Unlike the structure of the first embodiment, the first hole portion 36A is configured to extend from the discharge-side end face 31c to the position of the axis A2, inclined with respect to the axis A2. The first hole portion 36A is formed in the same number as the number of female teeth 31a of the female rotor 3A.
[0060] The second opening 37b of the second hole portion 37A opens onto the axial end face 33b of the discharge-side shaft portion 33. The axial end face 33b of the discharge-side shaft portion 33 is the axially most distal surface exposed to the discharge-side bearing chamber 56 shown in FIG. 1. The second opening 37b is disposed at the center position (axis A2) of the axial end face 33b. The second hole portion 37A is formed so as to extend from the most distal axial end face 33b along the axis A2 to the end position of the first hole portion 36A. Unlike the first embodiment, only one second hole portion 37A is formed.
[0061] The discharge hole 35A of the female rotor 3A thus configured is configured such that, when viewed from the direction of the axis A2 of the female rotor 3A, each first opening 36a on the discharge side end surface 31c of the female rotor 3A overlaps only with the recessed portion 67 (see FIG. 6) of the groove portion 65 of the discharge port 63 of the casing 4 every rotation (periodically) of the female rotor 3A. In other words, the discharge hole 35A of the female rotor 3A and the discharge port 63 of the casing 4 (see FIG. 6) are configured to periodically communicate with each other by each first opening 36a of the discharge hole 35A and the recessed portion 67 of the groove portion 65 periodically facing each other. Conversely, the discharge hole 35A of the female rotor 3A and the discharge port 63 of the casing 4 are configured such that the first opening 36a of the discharge hole 35A and the main opening 64 of the discharge port 63 are always avoided from facing each other. On the other hand, the discharge hole 35A has one second opening 37b provided in the axial end face 33b, which always communicates with the discharge-side bearing chamber 56.
[0062] In this embodiment, in the working chamber Cd in the final stage of the discharge stroke (the period when the volume approaches zero), the recess 67 of the groove 65 of the discharge port 63 faces the first opening 36a of the discharge hole 35A of the female rotor 3A, as in the first embodiment. That is, the groove body 66 of the groove 65 of the discharge port 63 communicates with the discharge hole 35A of the female rotor 3A through the recess 67. On the other hand, the second opening 37b of the discharge hole 35A always communicates with the discharge side bearing chamber 56, which has a lower pressure than the discharge flow passage 62. As a result, the liquid in the working chamber Cd is sucked from the groove body 66 of the groove 65 through the recess 67 into the discharge hole 35A, and is finally discharged to the discharge side bearing chamber 56. Therefore, it is possible to prevent overcompression, in which the pressure in the working chamber Cd rises suddenly due to liquid staying in the groove body 66 of the discharge port 63.
[0063] According to the second embodiment described above, similarly to the first embodiment, the second opening 37b on the other side of the discharge hole 35A of the female rotor 3A is communicated with the discharge-side bearing chamber 56 (bearing chamber) and the discharge hole 35A is configured so that the first opening 36a on one side periodically faces the groove 65 of the discharge port 63, so that the liquid in the working chamber Cd during the discharge stroke is sucked from the groove 65 of the discharge port 63 through the discharge hole 35A of the female rotor 3A into the discharge-side bearing chamber 56 (bearing chamber), which has a relatively lower pressure than the discharge port 63. Therefore, over-compression due to liquid entrapment in the working chamber Cd during the discharge stroke can be suppressed.
[0064] Moreover, the discharge hole 35A of the female rotor 3A according to this embodiment has a plurality of first openings 36a and one second opening 37b.
[0065] According to this configuration, it is only necessary to process the discharge hole 35A so that there is one second opening 37b, so that the number of processing steps can be reduced and processing becomes easier.
[0066] [Third embodiment] Next, a liquid feed type screw compressor according to a third embodiment of the present invention will be described with reference to Fig. 11. Fig. 11 is an explanatory diagram showing the positional relationship between the discharge port of the casing and the discharge hole opening on the discharge side end face of the female rotor in the liquid feed type screw compressor according to the third embodiment. In Fig. 11, the same reference numerals as those in Figs. 1 to 10 denote similar parts, and therefore detailed description thereof will be omitted.
[0067] The screw compressor 1B of the liquid feed type according to the third embodiment shown in Fig. 11 differs from the first embodiment (see Fig. 6) in that the configuration and structure of the discharge port 63B of the casing 4 are different, and therefore the communication relationship between the discharge port 63B of the casing 4 and the discharge hole 35 of the female rotor 3 is different. The other configurations of the screw compressor 1B of the liquid feed type according to the third embodiment are similar to those of the first embodiment.
[0068] Specifically, the discharge port 63B of the casing 4 has a main opening 64 similar to that of the first embodiment, and a groove 65B connected to the main opening 64 and different from that of the first embodiment. The groove 65B serves as the groove body 66 and the recess 67 of the groove 65 of the first embodiment. In detail, the groove 65B periodically and directly communicates with the first opening 36a of the discharge hole 35 of the female rotor 3 when the groove width is set to a condition that can avoid a communication state between the working chamber in the discharge stroke and the working chamber in the suction stroke. That is, the groove 65B of the discharge port 63B is configured to overlap (periodically) with each first opening 36a on the discharge side end surface 31c of the female rotor 3 when viewed from the axial direction (direction of the axis A2) of the female rotor 3. In other words, the discharge port 63B of the casing 4 and the discharge hole 35 of the female rotor 3 are configured to periodically communicate with each other by periodically opposing each first opening 36a of the discharge hole 35 to the groove portion 65B of the discharge port 63B.
[0069] In this embodiment, in the working chamber Cd in the final stage of the discharge stroke (the period when the volume approaches zero), the communication region D for the discharge port 63B moves to the groove portion 65B, as shown in the lower diagram of FIG. 11, for example. In detail, the communication region D of the working chamber Cd is at a position in the groove portion 65B that is relatively distant from the discharge-side shaft portion 33 of the female rotor 3. At the same time, the groove portion 65B of the discharge port 63B faces the first opening portion 36a of the discharge hole 35 of the female rotor 3. In other words, the groove portion 65B of the discharge port 63B is in direct communication with the discharge hole 35 of the female rotor 3.
[0070] As a result, when the liquid in the working chamber Cd, in which the communication region D for the discharge port 63B is located in the groove portion 65B, is discharged to the groove portion 65B side, it is sucked from the groove portion 65B through the first opening portion 36a into the discharge hole 35, and is finally discharged to the discharge-side bearing chamber 56. This makes it possible to prevent overcompression, in which the pressure in the working chamber Cd rises suddenly because the liquid cannot be discharged to the groove portion 65B due to the liquid remaining in the groove portion 65B of the discharge port 63B during the final stage of the discharge stroke (the period when the volume approaches zero), causing the pressure in the working chamber Cd to rise suddenly. Therefore, there is no power loss in the screw compressor due to such overcompression.
[0071] According to the above-mentioned third embodiment, similarly to the first embodiment, the second opening 37a on the other side of the discharge hole 35 of the female rotor 3 is communicated with the discharge-side bearing chamber 56 (bearing chamber) and the discharge hole 35 is configured so that the first opening 36a on one side periodically faces the groove 65B of the discharge port 63B, so that the liquid in the working chamber Cd during the discharge stroke is sucked from the groove 65B of the discharge port 63B through the discharge hole 35 of the female rotor 3 into the discharge-side bearing chamber 56 (bearing chamber) which has a relatively lower pressure than the discharge port 63B. Therefore, it is possible to suppress overcompression due to liquid entrapment in the working chamber Cd during the discharge stroke.
[0072] [Other embodiments] The present invention is not limited to the above-described embodiment, but includes various modified examples. The above-described embodiment has been described in detail to easily explain the present invention, and is not necessarily limited to those having all of the configurations described. That is, 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. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.
[0073] For example, in the above-described first to third embodiments, the discharge holes 35, 35A of the female rotors 3, 3A have a plurality of first openings 36a formed in the discharge side end surface 31c. However, the discharge holes 35, 35A of the female rotors 3, 3A may have at least one first opening 36a formed in the discharge side end surface 31c. [Explanation of symbols]
[0074] Explanation of the Reference Numerals 1...Liquid-feed screw compressor, 2...Male rotor, 3, 3A...Female rotor, 4...Casing, 8...Discharge-side bearing (bearing), 21c...Discharge-side end face, 31c...Discharge-side end face, 35, 35A...Discharge hole, 36a...First opening, 37a, 37b...Second opening, 45...Accommodation chamber, 49...Discharge-side inner wall surface, 56...Discharge-side bearing chamber (bearing chamber), 63, 63B...Discharge port, 64...Main opening, 65, 65B...Groove portion, 66...Groove body, 67...Recess, A1...Axis (first axis), A2...Axis (second axis), L...Reference line
Claims
1. a male rotor having a discharge end surface on one axial side and rotatable about a first axis; a female rotor having a discharge end surface on one axial side and rotatable about a second axis parallel to the first axis; a bearing that rotatably supports the female rotor at one axial end; a casing having an accommodation chamber that accommodates the male rotor and the female rotor rotatably in a state of being meshed with each other and a bearing chamber in which the bearing is disposed, the casing has a discharge port formed in a discharge side inner wall surface of the accommodation chamber facing the discharge side end surface of the male rotor and the discharge side end surface of the female rotor, The discharge port is a main opening formed in an area on one side away from a reference line that is a straight line passing through the first axis and the second axis, the main opening being defined based on a tooth profile on the discharge side end surface of the male rotor and a tooth profile on the discharge side end surface of the female rotor; a groove portion connected to an end portion of the main opening on the reference line side and close to the second axis line, the groove portion extending from the main opening toward the reference line side, the female rotor has a discharge hole having a first opening on one side that opens onto the discharge side end surface of the female rotor and a second opening on the other side that communicates with the bearing chamber, The first opening of the discharge hole is disposed so that its circumferential position on the female rotor corresponds to a tooth bottom on the discharge side end face of the female rotor, and is configured to periodically face the groove portion without always facing the main opening of the discharge port. Liquid-feed screw compressor.
2. 2. The liquid feed screw compressor according to claim 1, The groove portion of the discharge port is a groove body extending from the main opening toward the reference line and formed to a size such that the groove body is always avoided from opposing the first opening of the discharge hole; a recess connected to a portion of the groove body close to the second axis and periodically facing the first opening of the discharge hole; Liquid-feed screw compressor.
3. 2. The liquid feed screw compressor according to claim 1, The discharge hole has the first openings in the same number as the number of teeth of the female rotor. Liquid-feed screw compressor.
4. 2. The liquid feed screw compressor according to claim 1, The female rotor has a plurality of the discharge holes, Each of the discharge holes has one of the first openings and one of the second openings. Liquid-feed screw compressor.
5. 2. The liquid feed screw compressor according to claim 1, The discharge hole has a plurality of the first openings and a single second opening. Liquid-feed screw compressor.
Citation Information
Patent Citations
Oil free screw compressor
JP2010275931A
Cited By
Substrate processing apparatus and substrate processing method
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