Screw compressor

Abstract

A screw compressor capable of suppressing deformation around the opening is provided. The compressor (1) comprises: a pair of male and female rotors (2); a housing (6) having a rotor chamber (7) that houses the pair of rotors (2) and is divided circumferentially into an intake side and an exhaust side, and a bore wall (8) that defines the rotor chamber (7); an opening (20) provided in the bore wall (8) that opens the intake side of the rotor chamber (7) radially; an exhaust port (14) that discharges compressed fluid from the exhaust side of the rotor chamber (7); and a protrusion (40) provided around the opening (20) and protruding outward from the bore wall (8).

Description

Technical Field

[0001] This invention relates to a screw compressor. Background Technology

[0002] Patent Document 1 discloses a screw compressor having a bore wall defining a rotor chamber housing a pair of rotors. The bore wall includes a partially cylindrical male bore wall housing a male rotor and a partially cylindrical female bore wall housing a female rotor. Both the male and female bore walls have a certain thickness. In an orthogonal section, the arc representing the inner circumferential surface of the male bore wall and the arc representing the inner circumferential surface of the female bore wall form apexes at two points. The arc representing the outer circumferential surface of the male bore wall and the arc representing the outer circumferential surface of the female bore wall also form apexes at two points.

[0003] Patent document 2 discloses a screw compressor with an opening in the bore wall that connects the rotor chamber to the outside and a discharge port. The opening opens the rotor chamber radially and is also called a radial port. The opening is used for assembly or maintenance operations and also for drawing fluid into the rotor chamber. The discharge port discharges the compressed fluid from the rotor chamber. The opening exits from the discharge port in both the axial and circumferential directions.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 10-159766 Patent Document 2: Japanese Patent Application Publication No. 2015-48739. Summary of the Invention

[0005] The problem that the invention aims to solve When the compressor starts, the periphery of the discharge port heats up rapidly due to the compressed fluid, while the periphery of the opening remains at a low temperature because it carries the relatively cold fluid that flowed before compression. Due to this temperature difference, the bore wall undergoes uneven thermal expansion during the heating process, expanding unevenly in both the axial and circumferential directions. At this point, it can be recognized that, combined with the lower rigidity of the opening periphery, the bore wall deforms unevenly, potentially causing inward displacement of the opening periphery before it has fully heated up.

[0006] The objective of this invention is to provide a spiral compressor capable of suppressing deformation around the opening.

[0007] Methods used to solve problems One technical solution of the present invention provides a screw compressor comprising: a pair of male and female rotors; a housing having a rotor chamber that houses the pair of rotors and is circumferentially divided into an intake side and a discharge side, and a bore wall defining the rotor chamber; an opening provided in the bore wall that radially opens the intake side of the rotor chamber; a discharge port that discharges compressed fluid from the discharge side of the rotor chamber; and a protrusion provided at the periphery of the opening and protruding outward from the bore wall.

[0008] According to the above structure, the rigidity of the periphery of the opening is improved by providing the protrusion. Even if the bore wall deforms due to the temperature difference between the discharge and suction sides (circumferential temperature difference) or the temperature difference between the discharge end face and suction end face in the rotor chamber (axial temperature difference), deformation such as inward displacement at the periphery of the opening can be suppressed. Furthermore, since the protrusion protrudes outward from the bore wall, the clearance between the bore wall and the rotor can be appropriately ensured without affecting the inner circumferential surface.

[0009] Alternatively, the aforementioned bore wall may include a male bore wall defining a male rotor chamber that houses the male rotor of the aforementioned pair of rotors, and a female bore wall defining a female rotor chamber that houses the female rotor of the aforementioned pair of rotors; in an orthogonal section, the outer peripheral surface of the aforementioned suction side of the connection between the aforementioned male bore wall and the aforementioned female bore wall in the aforementioned bore wall other than the aforementioned protrusion extends along a common tangent of the inner peripheral surface of the aforementioned male bore wall on the aforementioned suction side and the inner peripheral surface of the aforementioned female bore wall on the aforementioned suction side.

[0010] According to the above structure, the thickness of the bore wall increases on the intake side with the opening. Therefore, the rigidity of the bore wall is improved on the intake side including the opening, which can further suppress deformation around the opening. In addition, the outer peripheral surface of the bore wall eliminates sharp points and becomes flat along a common tangent. Therefore, stress concentration caused by deformation around the opening can be mitigated.

[0011] Alternatively, the aforementioned housing may be formed from castings; in the aforementioned orthogonal cross section, the end face of the aforementioned protrusion extends along the aforementioned common tangent of the aforementioned inner circumferential surface of the aforementioned male cavity wall on the aforementioned suction side and the aforementioned inner circumferential surface of the aforementioned female cavity wall on the aforementioned suction side.

[0012] According to the above structure, since the thickness of the protrusion can be made uniform, casting defects such as poor shape and strain of the protrusion are less likely to occur when the shell is formed by casting.

[0013] Alternatively, the aforementioned opening may be a through hole, with the entire circumference of the aforementioned opening surrounded by the aforementioned protrusion.

[0014] According to the above structure, compared with the case of cutting the bore wall to form an opening, the periphery of the opening becomes less prone to deformation.

[0015] This screw compressor can also be an oil-free compressor.

[0016] Based on the above structure, without an oil injection system, the axial temperature difference of the compressor bore increases. If a protrusion is provided in this type of screw compressor, deformation around the opening can be effectively suppressed, which is therefore beneficial.

[0017] Invention Effects According to the present invention, a spiral compressor capable of suppressing deformation around the opening can be provided. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of the screw compressor according to the first embodiment.

[0019] Figure 2 yes Figure 1 A three-dimensional view of the bore wall and rotor.

[0020] Figure 3 yes Figure 1 III-III view.

[0021] Figure 4 yes Figure 2 A top view of the bore wall and rotor.

[0022] Figure 5 It is along Figure 4 The V-V line represents a partial sectional view of a screw compressor.

[0023] Figure 6 It is along Figure 4 The VI-VI line represents a partial sectional view of a screw compressor.

[0024] Figure 7 This is a top view of the bore wall and rotor of the screw compressor according to the second embodiment.

[0025] Figure 8 It is a three-dimensional view of the bore wall of a conventional screw compressor. Detailed Implementation

[0026] Hereinafter, the embodiments will be described with reference to the accompanying drawings. Furthermore, the same or corresponding elements are given the same reference numerals throughout the drawings, and repetition of detailed descriptions is omitted.

[0027] Figure 1 This is a cross-sectional view of the compressor 1 according to the first embodiment. Figure 2 From Figure 1 The three-dimensional view of compressor 1 is shown by extracting only a pair of rotors 2 and the bore wall 8. Figure 3 yes Figure 1The III-III view is an axial view taken from the suction end face 8b side. Figure 1 The diagram of housing 6 is shown, but the rotor 2 is omitted for the sake of clarity regarding rotor chamber 7. In the following description, "axial," "radial," and "circumferential" refer to the axis of rotor 2. "Upper" and "lower" correspond to... Figure 1 and Figure 3 The vertical direction on the paper, but only as a simple example of radial or circumferential region, can be appropriately varied according to the orientation of compressor 1. "Up" corresponds to the suction side of rotor chamber 7 in the circumferential direction, and "down" corresponds to the discharge side of rotor chamber 7 in the circumferential direction.

[0028] The compressor 1 in this embodiment is a screw compressor, which is an oil-free compressor. The compressor 1 has a pair of male rotors 2m and female rotors 2f (sometimes referred to together as rotors 2), a housing 6, and a cover 18.

[0029] Reference Figure 1 and Figure 2 The female rotor 2f has a rotor shaft 3f, a plurality of helical teeth 4f disposed on the outer periphery of the rotor shaft 3f, and helical tooth grooves 5f defined between adjacent teeth 4f. The rotor shaft 3f is rotatably supported relative to the housing 6 and the cover 18 via bearings 19 about the axis Af of the female rotor 2f.

[0030] Reference Figure 2 The male rotor 2m, similar to the one described above, has a rotor shaft (not shown), teeth 4m, and tooth grooves 5m, and is supported so as to be rotatable about its own axis Am. The rotor 2 is housed in the housing 6 with its two axes Am and Af extending parallel to each other, and the teeth 4m of the male rotor 2m engaging with the tooth grooves 5f of the female rotor 2f. The male rotor 2m is mechanically connected to a drive mechanism (not shown) including a motor and is driven to rotate by the drive mechanism. Alternatively, the female rotor 2f may be driven to rotate by the drive mechanism, either in place of the male rotor 2m or otherwise.

[0031] Reference Figure 1 The housing 6 has a bore wall 8, an end wall 8a, and an outer casing 9 that surrounds the bore wall 8. A rotor chamber 7, housing the rotor 2, is defined by the inner surfaces of the bore wall 8 and the end wall 8a. The rotor chamber 7 houses the rotor 2 and is thus divided circumferentially into an intake side and an exhaust side. The housing 6 is a cast metal product integrally formed with a dual structure of the bore wall 8 and the outer casing 9, and the bore wall 8 can be connected to the outer casing 9 via a connecting part 10. The outer casing 9 is generally elliptical cylindrical, defining an internal space 11 that houses the bore wall 8, at one axial end ( Figure 1 The right side of the paper is open. Cover 18 is securely attached to one end of outer box 9, sealing outer box 9.

[0032] Reference Figure 2 and Figure 3The rotor chamber 7 includes a male rotor chamber 7m that houses the male rotor 2m and a female rotor chamber 7f that houses the female rotor 2f, and is open at one axial end (towards the intake end face 8b). The bore wall 8 includes a male bore wall 8m that defines the male rotor chamber 7m and a female bore wall 8f that defines the female rotor chamber 7f. The other axial end of the rotor chamber 7 (towards the discharge end face) is closed by an end wall 8a.

[0033] The male rotor wall 8m and the female rotor wall 8f are partially cylindrical, resembling a C-shape when viewed axially. The centerline of the male rotor wall 8m is substantially aligned with the axis Am of the male rotor 2m, and the centerline of the female rotor wall 8f is substantially aligned with the axis Af of the female rotor 2f; the two centerlines extend parallel to each other. The male rotor wall 8m and the female rotor wall 8f are continuous at both the top and bottom. Thus, the rotor wall 8 as a whole appears roughly cocoon-shaped or gourd-shaped when viewed axially. The male rotor chamber 7m and the female rotor chamber 7f are spatially interconnected, capable of housing the male rotor 2m and the female rotor 2f in an engaged state.

[0034] Reference Figure 1 and Figure 3 The internal space 11 of the housing 6 includes a suction passage 12 for guiding fluid drawn into the compressor 1 from the outside of the compressor 1. The suction passage 12 communicates with a suction port 13 formed in the housing 18. The suction port 13 is connected to an opening at one axial end of the bore wall 8.

[0035] The housing 6 is provided with a discharge port 14. The discharge port 14 is provided, for example, axially at the other end of the bore wall 8, recessed in or extending through the end wall 8a. The discharge port 14 is provided circumferentially on the lower side of the bore wall 8.

[0036] Reference Figures 1-3 An opening 20 is provided in the bore wall 8. The opening 20 is also referred to as a radial port. The opening 20 radially opens the intake side of the rotor chamber 7, allowing the intake passage 12 to connect to the rotor chamber 7 via a different route than the intake port 13. The opening 20 is located axially near the intake end face 8b of the bore wall 8. The opening 20 is circumferentially located on the upper part of the bore wall 8. The opening 20 allows visual inspection of the interior of the rotor chamber 7 from the outer periphery of the bore wall 8. Operators can perform assembly or maintenance work on the compressor 1 while visually inspecting the engagement state of the rotor 2 housed in the rotor chamber 7 through the opening 20.

[0037] When viewed axially or in an orthogonal section, the opening 20 and the discharge port 14 are positioned on opposite sides of the straight line connecting the axis Am of the male rotor 2m and the axis Af of the female rotor 2f (see reference). Figure 3 or Figure 5In the example diagram, the straight line connecting the axes Am and Af extends horizontally, with the opening 20 positioned on the upper side and the discharge port 14 positioned on the lower side. Furthermore, in this invention, relative to the plane containing the axes Am and Af, the side where the opening 20 is located is designated as the suction side, and the side where the discharge port 14 is located is designated as the discharge side.

[0038] If rotor 2 is driven to rotate, the male rotor 2m and female rotor 2f rotate synchronously in an engaged state. Furthermore, fluid flows from the outside of housing 6 into suction passage 12. A portion of the fluid is drawn axially into rotor chamber 7 via suction port 13. A portion of the fluid can be drawn radially into the suction side of rotor chamber 7 via opening 20 from suction passage 12. The drawn-in fluid flows into tooth grooves 5m and 5f, where it is compressed and heated while being axially transported. The compressed fluid is discharged from the discharge side of rotor chamber 7 to the outside of housing 6 via discharge port 14.

[0039] Unless otherwise specified, the fluid compressed by compressor 1 will be assumed to be air. Before compressor 1 starts, the temperature of the casing 6 throughout the casing is the same as the ambient temperature (e.g., atmospheric temperature), i.e., room temperature. If compressor 1 starts, the discharge side of casing 6 is exposed to the high temperature of the compressed air and heats up. In contrast, the intake side of casing 6, since the incoming air is at atmospheric temperature, does not change significantly from room temperature. If compressor 1 continues to operate, the heat from the discharge side is transferred to the entire casing 6. The casing temperature throughout casing 6 becomes higher than the ambient temperature.

[0040] During the transition from compressor 1 startup to the stabilization of the casing temperature at high temperatures, especially immediately after startup, a significant temperature difference arises between the suction and discharge sides, or between the suction end face and the discharge end face. Thermal deformation of the casing 6 begins on the discharge side, with thermal deformation on the suction side occurring later. During this process, strain may occur on the suction side of the casing 6. If the strain is large, the suction side of the casing 6 may come into contact with the rotor 2.

[0041] In particular, in this embodiment, since the discharge port 14 and the opening 20 are separated not only axially but also circumferentially, the temperature difference is not easily eliminated (the transition condition is prone to become chronic), and strain is easily generated on the suction side. In this embodiment, since the compressor 1 is an oil-free compressor, compared with the case where the compressor 1 is an oil-injected compressor, the temperature difference between the suction side and the discharge side, or between the suction end face side and the discharge end face side, is prone to become larger, and strain is easily generated on the suction side. Furthermore, in this embodiment, an opening 20 that can also be used for various operations is additionally provided on the suction side of the bore wall 8, along with the suction port 13. Therefore, the rigidity of the suction side is relatively low, and strain is easily generated on the suction side. In the compressor 1 of this embodiment, the strain on the suction side under transition conditions is effectively suppressed by means of the following structure.

[0042] Figure 8 This is a three-dimensional diagram of the bore wall 8 from a previous example. Please refer to it together. Figure 2 and Figure 8 The male bore wall 8m has a male inner circumferential surface 31m that defines the male rotor chamber 7m, and a male outer circumferential surface 32m that is opposite to the rotor chamber 7. The female bore wall 8f has a female inner circumferential surface 31f that defines the female rotor chamber 7f, and a female outer circumferential surface 32f that is opposite to the rotor chamber 7.

[0043] In the following description, let the radius of the inner circumference of the male surface 31m be "male inner diameter rm", the radius of the inner circumference of the female surface 31f be "female inner diameter rf", the radius of the outer circumference of the male surface 32m be "male outer diameter Rm", and the radius of the outer circumference of the female surface 32f be "female outer diameter Rf". Furthermore, in the orthogonal section, let the straight-line distance between the two axis centers Am and Af be "center-to-center distance D" (refer to...). Figure 5 ).

[0044] The male inner circumferential surface 31m and the female inner circumferential surface 31f are circular arcs when viewed axially. The male inner diameter rm and the female inner diameter rf are constant axially. The male inner diameter rm is slightly larger than the radius of the tooth tip circle of the male rotor 2m. The female inner diameter rf is slightly larger than the radius of the tooth tip circle of the female rotor 2f, but smaller than the male inner diameter rm. The center-to-center distance D is larger than the difference between the male inner diameter rm and the female inner diameter rf, but smaller than the sum of the male inner diameter rm and the female inner diameter rf. Therefore, when viewed axially or in an orthogonal section of the axis, the circular arcs of the male inner circumferential surface 31m and the female inner circumferential surface 31f intersect at two points on opposite sides, i.e., the suction side and the discharge side, relative to the straight line connecting the axes Af and Am. In the following description, the lower intersection point is designated as "the first inner tip 33a", and the upper intersection point is designated as "the second inner tip 33b". The first inner tip 33a and the second inner tip 33b extend in a straight line along the axial direction.

[0045] Reference Figure 8In previous examples, the thickness of the bore wall 8 was constant throughout both the circumferential and axial directions. Furthermore, by setting the thickness to a constant during casting, the cooling rate can be made uniform, which has the advantage of easily obtaining the desired shape; therefore, the thickness is generally set in this way.

[0046] The outer diameter Rm of the male is the amount of thickness of the inner diameter rm of the male bore wall 8, and the outer diameter Rf of the female is the amount of thickness of the inner diameter rf of the female bore wall 8. When viewed axially or in an orthogonal section, the arcs of the outer circumferential surface 32m of the male and the outer circumferential surface 32f of the female intersect at two points, one above the other. In the following description, the lower intersection point is designated "first outer tip 34a", and the upper intersection point is designated "second outer tip 34b". The first outer tip 34a and the second outer tip 34b extend linearly along the axial direction.

[0047] Furthermore, in the conventional example, the opening 20 is provided on one end side (the suction end face 8b side) and the upper side of the bore wall 8 in the axial direction. The opening 20 is formed in a manner that spans both the male bore wall 8m and the female bore wall 8f. The second inner tip 33b and the second outer tip 34b are separated into one side and the other side in the axial direction due to the opening 20.

[0048] Reference Figure 2 In this embodiment, the compressor 1 includes a protrusion 40 located at the periphery of the opening 20 and protruding radially toward the outer periphery, opposite to the rotor chamber 7. The bore wall 8 is locally thickened at the periphery of the opening 20.

[0049] In addition, refer to Figure 2 and Figure 5 In this embodiment, when viewed in an orthogonal section or axially, the outer peripheral surface of the bore wall 8 extends along the common tangent TLa of the male inner peripheral surface 31m and the female inner peripheral surface 31f on the side closer to the opening 20, i.e., the suction side. Furthermore, two common tangents of the two circles intersecting at two points are drawn on the suction and discharge sides relative to the straight line connecting their centers.

[0050] The outer peripheral surface of the bore wall 8 includes not only the male outer peripheral surface 32m and the female outer peripheral surface 32f that intersect at the first outer tip 34a, but also a connecting surface 32a that connects the male outer peripheral surface 32m and the female outer peripheral surface 32f on the opposite side (towards the suction end face 8b) relative to the straight line connecting the axes Am and Af. The male outer peripheral surface 32m and the female outer peripheral surface 32f are partially cylindrical surfaces, while the connecting surface 32a is a flat surface. Within the orthogonal section of the axis, the male outer peripheral surface 32m and the female outer peripheral surface 32f are arcs, and the connecting surface 32a is formed by the common tangent TLb of the arcs of the male outer peripheral surface 32m and the female outer peripheral surface 32f on the suction side.

[0051] Reference Figure 4 and Figure 5The outer circumferential surface of the bore wall 8 extends along the common tangents TLa and TLb, so there is no longer any presence as in previous examples (see reference). Figure 8 The second outer tip 34b is embedded in the bore wall 8, which locally thickens in the circumferential direction on the side closer to the opening 20. The thickness of the bore wall 8 is maximized at the location where the second inner tip 33b is provided.

[0052] Reference Figure 4 The opening 20, viewed from above, is shaped like a home plate. The home plate is a right-angled pentagon with two adjacent right angles, and is a linearly symmetric convex pentagon. The opening 20 has five vertices: two right-angled vertices 21a, two obtuse-angled vertices 21b, and a central vertex 21c on the axis of symmetry C20. Furthermore, each vertex may be chamfered (R), and does not necessarily need to be sharp. In addition, the opening 20 has five edges: a transverse edge 22a connecting the right-angled vertices 21a to each other, a pair of longitudinal edges 22b connecting the right-angled vertices 21a and the obtuse-angled vertices 21b, and a pair of oblique edges 22c connecting the obtuse-angled vertices 21b and the central vertex 21c.

[0053] A pair of longitudinal edges 22b extend axially. A right-angled vertex portion 21a is positioned on one side of the axial direction (towards the suction end face 8b), and a central vertex portion 21c is positioned on the other side of the axial direction (towards the discharge end face). The axis of symmetry C20 of the opening 20 extends axially at a position offset relative to the second inner tip 33b towards the male bore wall 8m. The pair of longitudinal edges 22b extend along the ridge line 32b between the male outer peripheral surface 32m and the connecting surface 32a, and along the ridge line 32c between the female outer peripheral surface 32f and the connecting surface 32a. All or almost all of the transverse edge 22a and the pair of oblique edges 22c are located on the connecting surface 32a.

[0054] In this embodiment, the opening 20 is a through hole, and its entire circumference is surrounded by the bore wall 8. In other words, all five edges of the opening 20 are defined by the bore wall 8. The transverse edge 22a extends parallel to the periphery (suction end face 8b) of one end of the bore wall 8 when viewed from above. The bore wall 8 has a bridge portion 25 between the periphery and the transverse edge 22a, extending parallel to both the periphery and the transverse edge 22a, defining the opening 20.

[0055] The protrusion 40 completely surrounds the opening 20. In this embodiment, the protrusion 40 includes a transverse protrusion 41 provided along the transverse edge 22a of the bridge portion 25, a pair of longitudinal protrusions 42 provided along a pair of longitudinal edges 22b, and a pair of inclined protrusions 43 provided along a pair of oblique edges 22c. The transverse protrusion 41 forms a periphery at one end of the bore wall 8.

[0056] The protrusion 40 has a closed-loop end face 40a that surrounds the opening 20. The end face 40a is located radially on the outer periphery relative to the connecting surface 32a and is substantially parallel to the connecting surface 32a. The end face 40a is connected via an inclined surface 40b (see reference). Figure 5 and Figure 6 It is connected to the outer peripheral surface (connecting surface 32a, male outer peripheral surface 32m or female outer peripheral surface 32f) of the bore wall 8.

[0057] Thus, the compressor 1 of this embodiment includes: an opening 20 provided on the bore wall 8, which opens the suction side of the rotor chamber 7 in the radial direction; a discharge port 14, which discharges the compressed fluid from the discharge side of the rotor chamber 7; and a protrusion 40 provided on the periphery of the opening 20 and protruding outward from the bore wall 8.

[0058] By providing the protrusion 40, rigidity is increased around the opening 20. Even if the bore wall 8 deforms due to the temperature difference between the discharge and intake sides (circumferential temperature difference) and the temperature difference between the discharge end face and intake end face of the rotor chamber 7 (axial temperature difference), deformation such as inward displacement around the opening 20 can be suppressed. Furthermore, since the protrusion 40 protrudes outward from the bore wall 8, it does not affect the inner circumferential surface of the bore wall 8, thus appropriately ensuring the clearance between the bore wall 8 and the rotor 2.

[0059] The bore wall 8 includes a male bore wall 8m defining a male rotor chamber 7m that houses the male rotor 2m, and a female bore wall 8f defining a female rotor chamber 7f that houses the female rotor 2f. In an orthogonal section, in the bore wall 8 excluding the protrusion 40, the outer peripheral surface of the connection between the male bore wall 8m and the female bore wall 8f on the suction side extends along a common tangent TLa of the inner peripheral surface of the male bore wall 8m and the inner peripheral surface of the female bore wall 8f on the suction side. As a result, the thickness of the bore wall 8 increases on the suction side with the opening 20. Therefore, on the suction side including the opening 20, the rigidity of the bore wall 8 is improved, and deformation around the opening 20 can be further suppressed. In addition, the outer peripheral surface of the bore wall 8 eliminates the second outer tip and becomes flat along the common tangent TLa. Therefore, stress concentration caused by deformation around the opening 20 can be mitigated.

[0060] The housing 6 is formed from a casting. In an orthogonal section, the end face 40a of the protrusion 40 extends along the common tangent TLa of the male inner circumferential surface 31m on the suction side and the female inner circumferential surface 31f on the suction side. This makes the thickness of the protrusion 40 uniform. Therefore, when the housing 6 is formed from a casting, casting defects such as poor shape or strain of the protrusion 40 are less likely to occur.

[0061] The opening 20 is a through hole. The entire circumference of the opening 20 is surrounded by the protrusion 40. Therefore, compared with the case where the opening 20 is formed by cutting into the bore wall 8, the periphery of the opening 20 is less prone to deformation. In this embodiment, due to the presence of the bridge portion 25 of the bore wall 8 reinforced by the transverse protrusion 41, deformation of the periphery of the opening 20 is effectively suppressed.

[0062] The opening 20 and the discharge port 14 are separated in the orthogonal section of the shaft, positioned on opposite sides (i.e., the suction side and the discharge side) relative to the straight line connecting the axis Am of the male rotor 2m and the axis Af of the female rotor 2f. If the opening 20 and the discharge port 14 are thus circumferentially separated, heat conduction from the discharge side to the suction side takes time, and the temperature difference between the discharge and suction sides may be difficult to eliminate. Protrusion 40 in this configuration of the compressor 1 effectively suppresses deformation around the opening 20, which is advantageous.

[0063] Compressor 1 is an oil-free compressor. Because it does not employ an oil-injection system, the axial temperature difference of the bore wall 8 increases. Therefore, it is advantageous to provide a protrusion 40 in this type of compressor 1, as this effectively suppresses deformation around the opening 20.

[0064] Next, refer to Figure 7 The screw compressor 1 of the second embodiment will be described with a focus on the differences from the above-described embodiments.

[0065] In this embodiment, the opening 20 is a cut. A pair of longitudinal edges and a pair of oblique edges of the opening 20 are defined by the bore wall 8; furthermore, the opening 20 is open at one end of the bore wall 8. The protrusion 40 has a pair of longitudinal protrusions 42 and a pair of oblique protrusions. In this embodiment, the bore wall 8 does not have a bridge portion 25 (see reference). Figure 4 Protrusion 40 does not include transverse protrusion 41 (see reference). Figure 4 ).

[0066] However, in this embodiment, the rigidity around the opening 20 is also increased. Therefore, similar to the first embodiment, deformation around the opening 20 can be suppressed.

[0067] The structure of the above-described embodiment is merely a simple example and can be appropriately modified within the scope of this invention.

[0068] In the above embodiment, the protrusion 40 surrounds the entire circumference of the opening 20. The protrusion 40 may also be provided along a portion of the periphery of the opening 20.

[0069] In the above embodiment, the connecting surface 32a extends along the entire axial direction of the bore wall 8, and the second outer tip 34b is completely eliminated. The connecting surface 32a may also be partially provided axially along the bore wall 8.

[0070] In the above embodiment, both the connecting surface 32a and the end face 40a extend along the common tangent TLa of the male inner circumferential surface 31m and the female inner circumferential surface 31f in an axially orthogonal section, and are flat surfaces along the common tangent TLb of the male outer circumferential surface 32m and the female outer circumferential surface 32f. The connecting surface 32a may also be a curved surface that extends above the second inner tip 33b and below the common tangent TLb, or it may be a curved surface that extends above the common tangent TLb. The end face 40a is not limited to extending along the common tangent TLa, and may also be a surface parallel to an imaginary plane containing the axis Am of the male rotor 2m and the axis Af of the female rotor 2f.

[0071] In the above embodiment, the opening 20 is homeplate shaped (i.e., a linearly symmetrical and convex right-angled pentagon). The shape of the opening 20 is not particularly limited as long as it can fulfill the required functions of the opening 20 (e.g., operational upward movement and fluid intake), and can be appropriately changed to other shapes such as circles or rectangles.

[0072] In the above embodiment, compressor 1 is an oil-free compressor. The protrusion 40 and connecting surface 32a can also be applied to a screw compressor that is an oil-injected compressor. Furthermore, the connecting surface can be configured not only on the suction side but also to connect the male outer peripheral surface 32m and the female outer peripheral surface 32f on the discharge side.

[0073] This disclosure may include the following technical solutions.

[0074] (Technical Solution 1) A screw compressor includes: a pair of male and female rotors; a housing having a rotor chamber that houses the pair of rotors and is circumferentially divided into an intake side and a discharge side, and a bore wall defining the rotor chamber; an opening provided in the bore wall that radially opens the intake side of the rotor chamber; a discharge port that discharges compressed fluid from the discharge side of the rotor chamber; and a protrusion provided at the periphery of the opening and protruding outward from the bore wall.

[0075] (Technical Solution 2) As described in technical solution 1, the screw compressor has a bore wall comprising a male bore wall defining a male rotor chamber that houses the male rotor of the pair of rotors, and a female bore wall defining a female rotor chamber that houses the female rotor of the pair of rotors. In an orthogonal section, the outer peripheral surface of the connection between the male bore wall and the female bore wall of the bore wall, excluding the protrusion, extends along a common tangent to the inner peripheral surface of the male bore wall and the inner peripheral surface of the female bore wall on the suction side.

[0076] (Technical Solution 3) As described in technical solution 2, the screw compressor has a housing formed from castings; in the aforementioned axial orthogonal section, the end face of the aforementioned protrusion extends along the aforementioned common tangent of the aforementioned inner circumferential surface of the aforementioned male cavity wall on the aforementioned suction side and the aforementioned inner circumferential surface of the aforementioned female cavity wall on the aforementioned suction side.

[0077] (Technical Solution 4) In the screw compressor as described in any one of technical solutions 1 to 3, the aforementioned opening is a through hole, and the entire circumference of the aforementioned opening is surrounded by the aforementioned protrusion.

[0078] (Technical Solution 5) The screw compressor as described in any one of technical solutions 1 to 4 is an oil-free compressor.

[0079] Explanation of reference numerals in the attached figures 1. Compressor 2 rotors 2f Female rotor 2m male rotor 3f rotor shaft 4f, 4m teeth 5f, 5m tooth groove 6. Shell 7 Rotor Chamber 7f Female rotor chamber 7m male rotor chamber 8 chamber wall 8a end wall 8b Suction end face 8f vaginal wall 8m male chamber wall 9 outer box 10 Connecting parts 11. Interior Space 12 Inhalation route 13 Intake port 14 Discharge Port 18 masks 19 bearings 20 Opening 21a Right-angle vertex 21b Obtuse angle vertex 21c Central Vertex 22a Horizontal edge 22b Longitudinal edge 22c Beveled edge 25. Bridge section 31f Inner circumference of the vagina 31m inner circumference of the sun 32a Connection surface 32b, 32c edge lines 32f outer peripheral surface 32m outer perimeter of the sun 33a First inner tip 33b Second inner tip 34a First outer tip 34b Second outer tip 40. Protrusion 40a end face 40b Inclined surface 41 Transverse protrusion 42 Longitudinal protrusion 43. Inclined protrusion Af, Am axis C20 axis of symmetry D. Intercenter distance Rf female outer diameter Rm Yang outer diameter rf vaginal diameter rm male inner diameter TLa and TLb share the same tangent.

Claims

1. A screw compressor, have: A pair of yin and yang rotors; The housing has a rotor chamber that houses the aforementioned pair of rotors and is divided circumferentially into an intake side and an exhaust side, and a bore wall that defines the aforementioned rotor chamber; An opening is provided in the aforementioned bore wall, which radially opens the aforementioned suction side of the aforementioned rotor chamber; The discharge port discharges the compressed fluid from the aforementioned discharge side of the aforementioned rotor chamber; as well as The protrusion is located around the periphery of the aforementioned opening and protrudes outward from the aforementioned bore wall.

2. The screw compressor as described in claim 1, characterized in that, The aforementioned bore wall includes the male bore wall defining the male rotor chamber that houses the male rotor of the aforementioned pair of rotors, and the female bore wall defining the female rotor chamber that houses the female rotor of the aforementioned pair of rotors. In an orthogonal section, in the aforementioned bore wall other than the aforementioned protrusion, the outer peripheral surface of the aforementioned suction side at the connection between the aforementioned male bore wall and the aforementioned female bore wall extends along the common tangent of the inner peripheral surface of the aforementioned male bore wall on the aforementioned suction side and the inner peripheral surface of the aforementioned female bore wall on the aforementioned suction side.

3. The screw compressor as described in claim 2, characterized in that, The aforementioned shell is formed from castings; In the aforementioned orthogonal cross section, the end face of the aforementioned protrusion extends along the aforementioned common tangent of the aforementioned inner circumferential surface of the aforementioned male cavity wall on the aforementioned suction side and the aforementioned inner circumferential surface of the aforementioned female cavity wall on the aforementioned suction side.

4. The screw compressor as described in claim 1, characterized in that, The aforementioned opening is a through hole, and the entire circumference of the aforementioned opening is surrounded by the aforementioned protrusion.

5. The screw compressor as described in any one of claims 1 to 4, characterized in that, This screw compressor is an oil-free machine.

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