Screw compressor casing

Abstract

To achieve higher workability by enabling the assembly of a casing of a screw compressor with the smallest possible number of bolts.SOLUTION: In a casing 10 of a screw compressor 1 consisting of a cylinder casing 20, an inlet casing 30, and a gear casing 40, a flange 35 mounted to the inlet casing 30 oppositely to a suction side end face 20a of the cylinder casing 20 is mounted to the cylinder casing 20 with auxiliary bolts 81. The face of the inlet casing 30 mounted to the cylinder casing 20, on the opposite side to the flange 35, is disposed oppositely to a mounted face 42 of the gear casing 40, and then the cylinder casing 20, the inlet casing 30, and the gear casing 40 are overlapped with one another. In such a state, a jointly fastening bolt fastens the cylinder casing 20 penetrating through a through-hole 38 provided in the flange 35 of the inlet casing 30 to the gear casing 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a casing for a screw compressor, and more particularly to a casing for a screw compressor characterized by a structure in which the components of the casing are fastened together with bolts. [Background technology]

[0002] As an example of the configuration of the casing 110 of the screw compressor 100, an example of the configuration of the casing 110 shown in FIG. 3 of Patent Document 1, which will be described later, is shown in FIG.

[0003] The casing 110 of the screw compressor 100 shown in Figure 8 is composed of a cylinder casing 120, an inlet casing 130 fastened to the suction side end face 120a of the cylinder casing 120 by bolts, and a gear casing 140 fastened to the inlet casing 130 on the opposite side of the cylinder casing 120.

[0004] Of these, the cylinder casing 120 is provided with a rotor chamber 121 that rotatably accommodates a pair of male and female screw rotors 150, 160, and of the rotor shafts 151, 152; 161, 162 provided on the pair of screw rotors 150, 160, shaft holes 123, 124 that accommodate the discharge side rotor shafts 152, 162 are formed in a part of the cylinder casing 120 that is located on the discharge side relative to the rotor chamber 121, and shaft holes 131, 132 that accommodate the suction side rotor shafts 151, 161 are formed in the aforementioned inlet casing 130.

[0005] These shaft holes 123, 124, 131, 132 are provided with bearings 125, 126, 133, 134 that rotatably support the rotor shafts 151, 152; 161, 162, respectively, thereby allowing the pair of screw rotors 150, 160 mentioned above to mesh and rotate within the rotor chamber 121.

[0006] In addition, the suction side rotor shaft 151 provided on either the male or female screw rotor (the male screw rotor 150 in the illustrated embodiment) has a driven gear 173 attached to its shaft end within the gear casing 140, and a drive gear 174 is provided within this gear casing 140 to which rotational driving force is input from a driving source not shown, such as an engine or motor, so that by meshing the aforementioned driven gear 173 with the drive gear 174 within the gear casing 140 and operating the driving source not shown, the pair of male and female screw rotors 150, 160 can be meshed and rotated.

[0007] As described above, in the casing 110 of the screw compressor 100, which consists of the cylinder casing 120, the inlet casing 130, and the gear casing 140, the fastening between the cylinder casing 120 and the inlet casing 130 is performed by aligning the suction side end face 120a of the cylinder casing 120 and the cylinder casing 120 side end face of the inlet casing 130, and aligning the flange 129 provided on the suction side of the cylinder casing 120 and the flange 135 on the cylinder casing 120 side of the inlet casing 130, and tightening them with bolts 183, as shown in Figure 9.

[0008] In addition, between the inlet casing 130 and the gear casing 140, the end face of the inlet casing on the gear casing 140 side and the mounting surface 142 of the gear casing 140 are arranged facing each other, and a flange 136 provided on the gear casing 140 side of the inlet casing 130 and the gear casing 140 are fastened with bolts 184.

[0009] To assemble the screw compressor 100 having the casing 110 configured in this manner, first, a pair of male and female screw rotors 150, 160 are accommodated in the rotor chamber 121 of the cylinder casing 120, then the suction side opening of the rotor chamber 121 provided in the cylinder casing 120 is closed with the inlet casing 130, and necessary parts such as bearings 125, 126, 133, 134 are attached. Then, a bolt 183 is inserted into a through hole provided in the flange 129 of the cylinder casing 120, and the tip of the bolt 183 is screwed into a threaded hole provided in the flange 135 on the cylinder casing side of the inlet casing 130, thereby fastening the cylinder casing 120 and the inlet casing 130 together.

[0010] Then, a bolt 184 is inserted from the inlet casing 130 side toward the gear casing 140 side through a through hole provided in the flange 136 on the gear casing 140 side of the inlet casing 130, and the tip of the bolt 184 is screwed into a screw hole provided in the mounting surface 142 of the gear casing 140, thereby fastening the inlet casing 130 and the gear casing 140 together. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-243281 Summary of the Invention [Problem to be solved by the invention]

[0012] In the casing 110 of the conventional screw compressor 100 described above, the cylinder casing 120 and the inlet casing 130 must be fastened together, and the inlet casing 130 and the gear casing 140 must be fastened together separately.

[0013] Furthermore, in order to apply appropriate surface pressure between the cylinder casing 120 and the inlet casing 130, and between the inlet casing 130 and the gear casing 140, a relatively large number of bolts 183, 184 were required to fasten the cylinder casing 120 and the inlet casing 130, and between the inlet casing 130 and the gear casing 140, respectively, which resulted in the assembly work taking a long time.

[0014] Moreover, since the inlet casing 130 is fastened to the gear casing 140 by inserting the bolts 184 from the inlet casing 130 side toward the gear casing 140 side and fastening them, it is necessary to ensure a space S on the back surface of the flange 136 provided at the end of the inlet casing 130 on the gear casing 140 side, in which the bolts 184 can be inserted into through holes provided in the flange 136 and which can receive a fastening tool for fastening the bolts 136. This increases the overall length of the inlet casing 130 in the axial direction of the rotor shafts 151, 161, causing the screw compressor 100 to become larger.

[0015] The present invention has been made to overcome the drawbacks of the above-mentioned conventional technology, and aims to improve the workability of assembling the casing of a screw compressor by reducing the total number of bolts used to fasten the cylinder casing and inlet casing, and the inlet casing and gear casing, while applying appropriate surface pressure between each casing, while having a relatively simple configuration.Furthermore, it aims to provide a casing for a screw compressor that can minimize the overall length of the inlet casing in the axial direction of the rotor shaft, thereby contributing to the miniaturization and weight reduction of the screw compressor. [Means for solving the problem]

[0016] The means for solving the problems are described below together with the reference numerals used in the description of the embodiment of the invention. These reference numerals are intended to clarify the correspondence between the claims and the description of the embodiment of the invention, and needless to say, are not used to restrict the interpretation of the technical scope of the present invention.

[0017] In order to achieve the above object, the casing 10 of the screw compressor 1 of the present invention is The casing 10 of the screw compressor 1 is provided with a cylinder casing 20 having a rotor chamber 21 in which a pair of male and female screw rotors 50, 60 are housed so as to be meshed and rotatable, an inlet casing 30 that closes the suction side opening of the rotor chamber 21 provided in the cylinder casing 20, and a gear casing 40 that houses a driven gear 73 attached to the suction side rotor shaft 51 of either the male or female screw rotor (the male screw rotor 50 in the illustrated example) in mesh with a drive gear 74 to which rotational driving force from a drive source (not shown) is input, and seal members are provided between the cylinder casing 20 and the inlet casing 30 and between the inlet casing 30 and the gear casing 40, The inlet casing 30 is provided with a flange 35 that is attached to face the suction side end surface 20a formed around the suction side opening of the rotor chamber 21 of the cylinder casing 20, and auxiliary bolts 81 are provided to attach the flange 35 to the cylinder casing 20. The surface of the flange 35 of the inlet casing 30 attached to the cylinder casing 20 opposite the cylinder casing 20 side is aligned with the mounting surface 42 provided on the gear casing 40, and in this state the cylinder casing 20, the inlet casing 30, and the gear casing 40 are stacked together, and the cylinder casing 20 and the gear casing 40 are fastened together by passing through the through holes (through holes 38 for co-fastening bolts) provided in the flange 35 of the inlet casing 30. Multiple Co-tightening bolt 8 2 is placed around the intake side opening of the rotor chamber 21. The present invention is characterized by the provision of a stator (claim 1).

[0018] A through hole 36 for an auxiliary bolt into which the auxiliary bolt 81 is inserted is provided in the flange 35 of the inlet casing, and a screw hole 27 for an auxiliary bolt into which the auxiliary bolt 81 is screwed is provided in the suction side end surface 20a of the cylinder casing 20 at a position corresponding to the opening position of the through hole 36 for the auxiliary bolt, and the auxiliary bolt 81 is inserted into the through hole 36 for the auxiliary bolt and the tip is screwed into the screw hole for the auxiliary bolt, thereby attaching the inlet casing 30 to the cylinder casing 20, A countersink 36a may be provided at the end of the through hole 36 for the auxiliary bolt provided in the flange 35 of the inlet casing 30 on the gear casing 40 side (Figure 1), or a fitting hole 43 for receiving the head of the auxiliary bolt 81 may be provided in the mounting surface 42 of the gear casing 40 (variant 1 of Figure 1) (Claim 2).

[0019] As mentioned above, the tip of the auxiliary bolt 81 inserted into the through hole 36 for the auxiliary bolt from the gear casing 40 side toward the inlet casing 30 side is screwed into the screw hole 27 for the auxiliary bolt provided on the intake side end surface 20a of the cylinder casing 20, and the inlet casing 30 is attached to the cylinder casing 20, and When the screw compressor 1 is an oil-free screw compressor, the cylinder casing 20 is provided with a refrigerant flow path (oil jacket) 22 into which a refrigerant (cooling oil) is introduced (see Figures 2(B) and 3), and the inlet casing 30 is configured to close the suction side opening of the refrigerant flow path 22, A portion of the screw hole 27 for the auxiliary bolt into which the tip of the auxiliary bolt 81 is screwed may be provided on the suction side end face 20a of the cylinder casing 20 between the suction side opening of the rotor chamber 21 and the suction side opening of the refrigerant flow path 22 (Claim 3: see Figure 3).

[0020] The number of the auxiliary bolts 81 may be less than the number of the co-fastening bolts 82 (claim 4).

[0021] Furthermore, the auxiliary bolts 81 may be disposed between the adjacent co-fastening bolts 82, 82 (claim 5). [Effects of the Invention]

[0022] With the configuration of the present invention described above, the screw compressor 1 equipped with the casing 10 of the present invention can achieve the following significant effects.

[0023] The auxiliary bolts 81 are used when attaching the inlet casing 30 to the cylinder casing 20, and the surface pressure between the cylinder casing 20 and the inlet casing 30 required when the screw compressor 1 is operating is obtained by the cooperation of the auxiliary bolts 81 and the co-fastening bolts 82 used when fastening the cylinder casing 20 with the inlet casing 30 attached to the gear casing 40.This makes it possible to reduce the total number of bolts used compared to the conventional casing 110 described with reference to Figures 8 and 9, in which the cylinder casing 120 and the inlet casing 130, and the inlet casing 130 and the gear casing 140 are each fastened separately at two points.

[0024] As a result, the workability when assembling the casing 10 was significantly improved.

[0025] Furthermore, by applying the axial force of the auxiliary bolt 81 and the axial force of the co-tightening bolt 82, the cylinder casing 20 and the inlet casing 30 can be fastened together at a higher surface pressure than the surface pressure between the inlet casing 30 and the gear casing 40, which is applied only by the axial force of the co-tightening bolt 82, thereby preventing the compressed gas in the rotor chamber 21 from leaking outside the machine, and, if an oil jacket 22 described below is provided, preventing the cooling oil in the oil jacket 22 from leaking outside the machine or into the rotor chamber 21.

[0026] Furthermore, in the conventional structure of the casing 110 described with reference to Figures 8 and 9, in order to attach and detach the bolts used to fasten the inlet casing 130 and the gear casing 140, it was necessary to secure the space S necessary for operating the fastening tool on the back of the flange 136 provided at the end of the inlet casing 130 on the gear casing 140 side, and in order to secure this space S, the overall length of the inlet casing 130 in the axial direction of the rotor shafts 151, 161 was increased.However, with the configuration of the present invention, it is not necessary to secure such space S, and as a result, the overall length of the inlet casing 30 in the axial direction of the rotor shafts 51, 61 can be shortened, making it possible to reduce the size and weight of the casing 10 and, ultimately, the size and weight of the screw compressor 1.

[0027] When the casing 10 of the present invention is used as the casing of an oil-free screw compressor in which a refrigerant flow path (oil jacket) 22 is formed within the cylinder casing 20, a portion of the screw hole 27 for the auxiliary bolt into which the tip of the auxiliary bolt 81 is screwed can be provided on the suction side end face 20a of the cylinder casing 20 between the opening of the rotor chamber 21 and the opening of the refrigerant flow path (oil jacket) 22, thereby increasing the surface pressure between the portion of the suction side end face 20a of the cylinder casing 20 between the rotor chamber 21 and the refrigerant flow path (oil jacket) 22 and one surface 35a of the flange 35 of the inlet casing 30, making it even more difficult for the refrigerant (lubricating oil) in the refrigerant flow path 22 to leak toward the rotor chamber 21.

[0028] Furthermore, by reducing the number of auxiliary bolts 81 compared to the number of co-tightening bolts 82, the total number of bolts used in assembling the casing 10 is significantly reduced, thereby further improving workability when assembling the casing 10.On the other hand, since the surface pressure between the cylinder casing 20 and the inlet casing 30 is exerted not only by the auxiliary bolts 81 but also by the co-tightening bolts 82, the required surface pressure between the cylinder casing 20 and the inlet casing 30 can be ensured even if the number of auxiliary bolts 81 is reduced.

[0029] Furthermore, in a configuration in which the auxiliary bolts 81 are placed between each of the adjacent co-tightening bolts 82, 82, the bolt mounting pitch is shortened, thereby improving the surface pressure between the cylinder casing 20 and the inlet casing 30, and making it possible to withstand use in screw compressors 1 used under harsher conditions, such as screw compressors used to generate high-pressure compressed gas. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a cross-sectional plan view of a screw compressor equipped with a casing of the present invention. [Figure 2] 1A and 1B are exploded perspective views of the casing of the screw compressor of the present invention, where FIG. 1A is a view from the cylinder casing side, and FIG. 1B is a view from the gear casing side. [Figure 3] FIG. 2 is a view of the cylinder casing from the intake end face side. [Figure 4] FIG. 10 is a view of the inlet casing from the mating surface side with the gear casing. [Figure 5] A view of the cylinder casing (without refrigerant flow path) viewed from the suction end face. [Figure 6] FIG. 10 is a view of a cylinder casing (without a refrigerant flow path) viewed from the suction end face side (an example in which the formation position of a screw hole 27 for an auxiliary bolt is changed compared to FIG. 5). [Figure 7] FIG. 2 is a plan view of the assembled casing of the present invention. [Figure 8] 1 is a cross-sectional plan view of a screw compressor equipped with a conventional casing (corresponding to FIG. 3 of Patent Document 1). [Figure 9] FIG. 1 is a cross-sectional plan view of a screw compressor equipped with a conventional casing. DETAILED DESCRIPTION OF THE INVENTION

[0031] The casing 10 of the screw compressor 1 of the present invention will be described below with reference to the accompanying drawings.

[0032] In Figure 1, the symbol 1 denotes a screw compressor equipped with a casing 10 of the present invention, and the casing 10 of this screw compressor 1 is composed of a cylinder casing 20, an inlet casing 30 fastened to the suction side end face 20a of the cylinder casing 20, and a gear casing 40 fastened to the inlet casing 30 on the opposite side to the cylinder casing 20.

[0033] The cylinder casing 20 has a rotor chamber 21 formed therein that rotatably houses a pair of male and female screw rotors 50, 60, and is configured so that the male screw rotor 50 and the female screw rotor 60 mesh and rotate within this rotor chamber 21, thereby compressing the gas to be compressed.

[0034] Rotor shafts 51, 52, 61, 62, which are rotating shafts, are protruding from both ends of each of the pair of male and female screw rotors 50, 60 housed in the rotor chamber 21, and the inlet casing 30 that closes the suction side opening of the aforementioned cylinder casing 20 is provided with axial holes 31, 32 into which the suction side rotor shafts 51, 61 are inserted, and bearings (cylindrical roller bearings) 33, 34 that support the suction side rotor shafts 51, 61 inserted into the axial holes 31, 32.

[0035] On the other hand, in the part of the cylinder casing 20 located on the discharge side of the rotor chamber 21, axial holes 23, 24 are provided into which the discharge side rotor shafts 52, 62 of the screw rotors 50, 60 are inserted, and bearings 25, 26 are provided to support the discharge side rotor shafts 52, 62 inserted into these axial holes 23, 24.

[0036] In the embodiment shown in Figure 1, the screw compressor 1 equipped with the casing 10 of the present invention is an oil-free screw compressor that compresses the gas to be compressed by the non-contact intermeshing rotation of a pair of male and female screw rotors 50, 60 without introducing lubricating oil for lubrication, cooling, and sealing into the compression working space, and in order to intermesh and rotate the pair of male and female screw rotors 50, 60 in a non-contact state, timing gears 71, 72 are attached to the axial end of the discharge side rotor shaft 52 of the male screw rotor 50 and the axial end of the discharge side rotor shaft 62 of the female screw rotor 60, respectively.

[0037] Furthermore, of the axial holes 31, 32 provided in the inlet casing 30, the axial hole 31 into which the suction side rotor shaft 51 of the male screw rotor 50 is inserted is formed through the inlet casing 30, and the tip of the suction side rotor shaft 51 of the male screw rotor 50 protrudes through this axial hole 31 into a gear chamber 41 formed in the gear casing 40.

[0038] The driven gear 73 attached to the tip of the suction side rotor shaft 51 of the male screw rotor 50 is meshed with a drive gear 74 within the gear chamber 41 to which rotational driving force is transmitted from a drive source (not shown), such as an engine or motor, so that the screw rotors 50, 60 can be meshed and rotated in a non-contact state by operating the drive source.

[0039] In Figures 2(B) and 3, the symbol 22 denotes a refrigerant flow path (oil jacket in this embodiment) into which a refrigerant such as cooling oil is introduced, which is formed below the rotor chamber 21 and parallel to the rotor chamber 21, and opens at the suction side end face 20a of the cylinder casing 20.By passing cooling oil through this oil jacket 22, the cylinder casing 20 heated by the heat of compression can be cooled.

[0040] The formation of an oil jacket 22 on such a cylinder casing 20 is a configuration adopted in an oil-free screw compressor in which no lubricating oil is introduced into the compression working space, and when the casing 10 of the present invention is applied to an oil-cooled screw compressor, it can be configured without an oil jacket 22 as shown in Figures 5 and 6.

[0041] The assembly of the casing 10 begins with attaching the inlet casing 30 to the cylinder casing 20 having the above-described configuration.

[0042] Thereafter, the cylinder casing 20 to which the inlet casing 30 is attached is fastened to the gear casing 40, whereby the casing 10 of the present invention, which is made up of the cylinder casing 20, the inlet casing 30, and the gear casing 40, is assembled.

[0043] When installing the inlet casing 30, a pair of male and female screw rotors 50, 60 are installed in advance inside the rotor chamber 21 of the cylinder casing 20, and in this state, the intake side openings of the rotor chamber 21 of the cylinder casing 20 and the oil jacket 22 are blocked with the inlet casing 30 via sealing members such as O-rings, gaskets, and liquid gaskets (O-rings in the illustrated example), thereby preventing the compressed gas in the rotor chamber 21 from leaking outside the machine and preventing the cooling oil in the oil jacket 22 from leaking outside the machine or into the rotor chamber 21, and allowing necessary equipment such as bearings 25, 26, 33, 34 to be installed in the axial holes 23, 24 of the inlet casing 30.

[0044] In order to enable attachment to the cylinder casing 20, the inlet casing 30 is provided with a flange 35, and by attaching the inlet casing 30 to the cylinder casing 20 with one surface 35a of this flange 35 facing the suction side end surface 20a of the cylinder casing 20, the inlet casing 30 is configured to block the suction side openings of the rotor chamber 21 and oil jacket 22 provided in the cylinder casing 20.

[0045] The flange 35 of the inlet casing 30 is also formed with another surface 35 b that faces the mounting surface 42 provided on the gear casing 40 .

[0046] In this embodiment, as shown in Figure 4, a boss portion 37 is provided on the end face of the inlet casing 30 on the fastening side with the gear casing 40, extending the axial holes 31, 32 toward the gear casing 40, and an opening 45 is formed in the side wall of the gear casing 40 to receive this boss portion 37.By inserting the boss portion 37 into this opening 45, the other surface 35b of the flange 35 of the inlet casing 30 can be made to face the mounting surface 42 formed on the periphery of the opening 45.

[0047] In addition, a sealing member such as an O-ring, gasket, or liquid gasket (an O-ring in this embodiment) is sandwiched between the other surface 35b of the flange 35 of the inlet casing 30 and the mounting surface 42 of the gear casing 40, thereby preventing the lubricating oil in the gear chamber 41 from leaking outside the machine from between the other surface 35b of the flange 35 of the inlet casing 30 and the mounting surface 42 of the gear casing 40.

[0048] The inlet casing 30 is attached to the cylinder casing 20 as an intermediate step in the assembly of the casing 10 using auxiliary bolts 81 shown in FIGS.

[0049] Furthermore, the attachment of the inlet casing 30 to the cylinder casing 20 with the auxiliary bolts 81, which is carried out in the intermediate step of assembling the casing 10, does not necessarily need to generate the surface pressure required when the casing is finally assembled into the screw compressor 1, but it is sufficient that when the inlet casing 30 is fastened to the gear casing 40 together with the cylinder casing 20 with the co-tightening bolts 82 described below, the axial force of the co-tightening bolts 82 is supplemented by the axial force of the auxiliary bolts 81 to obtain the required surface pressure.

[0050] In order to enable the inlet casing 30 to be attached to the cylinder casing 20 using this auxiliary bolt 81, in the illustrated example, a through hole 36 for the auxiliary bolt is provided in the flange 35 of the inlet casing 30 to insert the auxiliary bolt 81.

[0051] The tip of the auxiliary bolt 81 inserted into the through hole 36 for the auxiliary bolt from the gear casing 40 side is screwed into the screw hole 27 for the auxiliary bolt provided on the suction side end face 20a of the cylinder casing 20, thereby making it possible to attach the inlet casing 30 to the suction side end face 20a of the cylinder casing 20.

[0052] In this configuration, in which the inlet casing 30 is attached to the cylinder casing 20 by an auxiliary bolt 81 inserted from the gear casing 40 side into the through hole 36 for the auxiliary bolt provided in the flange 35 of the inlet casing 30, when the cylinder casing 20 with the inlet casing 30 attached is fastened to the gear casing 40 in this manner, a countersink 36a is provided at the end of the through hole 36 for the auxiliary bolt on the gear casing 40 side so that the head of the auxiliary bolt 81 does not interfere with the mounting surface 42 of the gear casing 40, and the head of the auxiliary bolt 81 can be immersed in this countersink 36a.

[0053] In addition, as a configuration to avoid interference between the head of the auxiliary bolt 81 and the mounting surface 42 of the gear casing 40, a fitting hole 43 into which the head of the auxiliary bolt 81 fits can be formed at a corresponding position on the mounting surface 42 of the gear casing 40 (see "Variant 1" in Figure 1).By configuring in this way, when fastening the cylinder casing 20 to which the inlet casing 30 is attached to the gear casing 40, the head of the auxiliary bolt 81 can be fitted into this fitting hole 43, making it possible to easily align the inlet casing 30 to the specified mounting position.

[0054] As mentioned above, in the casing of an oil-free screw compressor which has an oil jacket 22 in addition to the rotor chamber 21 inside the cylinder casing 20, as shown in Figure 3, part of the screw hole 27 for the auxiliary bolt provided on the suction side end face 20a of the cylinder casing 20 is provided at a position between the rotor chamber 21 and the oil jacket 22, and a through hole 36 for the auxiliary bolt mentioned above is provided in the flange 35 of the inlet casing 30 at a position corresponding to this screw hole 27 for the auxiliary bolt, so that the inlet casing can be attached to the cylinder casing with the auxiliary bolt 81 mentioned above using this screw hole 27 for the auxiliary bolt and the through hole 36 for the auxiliary bolt.

[0055] In this way, by providing a screw hole 27 for an auxiliary bolt at a position between the rotor chamber 21 and the oil jacket 22 and attaching an auxiliary bolt 81, the surface pressure between the portion of the suction side end face 20a of the cylinder casing 20 between the rotor chamber 21 and the oil jacket 22 and one face 35a of the flange 35 of the inlet casing 30 can be increased, making it difficult for the cooling oil in the oil jacket 22 to leak toward the rotor chamber 21.

[0056] Furthermore, when the casing 10 of the present invention is applied to an oil-cooled screw compressor that does not have the aforementioned oil jacket 22, threaded holes 27 for auxiliary bolts may be provided on the peripheral portion of the suction side end face 20a of the cylinder casing 20, and through holes 36 for auxiliary bolts may be provided on the peripheral portion of the flange 35 of the inlet casing 30 at the positions where the threaded holes 27 for the auxiliary bolts are formed, thereby attaching the inlet casing 30 to the cylinder casing 20.

[0057] In this case, as shown in Figure 5, the number of threaded holes 27 for auxiliary bolts formed on the suction side end face 20a of the cylinder casing 20, and therefore the number of auxiliary bolts 81 used, may be reduced (two in the illustrated example).

[0058] In addition, in cases where it is necessary to increase the surface pressure between the cylinder casing 20 and the inlet casing 30, such as in a screw compressor 1 used to compress high-pressure compressed gas, as shown in Figure 6, screw holes 27 for auxiliary bolts may be formed between the through holes 28 or screw holes 28' for the co-tightening bolts formed at the mounting positions of the co-tightening bolts 82 described below, and the auxiliary bolts 81 may be arranged between each of the adjacent co-tightening bolts 82.

[0059] In the configuration of the casing 10 described with reference to Figure 1, the inlet casing 30 is attached to the cylinder casing 20 by screwing the tip of the auxiliary bolt 81 inserted into the through hole 36 for the auxiliary bolt from the gear casing 40 side into the screw hole 27 for the auxiliary bolt provided on the suction side end face 20a of the cylinder casing 20.

[0060] However, the attachment of the inlet casing 30 to the cylinder casing 20 is not limited to this configuration, and instead of or in combination with the above configuration, as shown as "Variant 2" in Figure 1, a through hole 27' for an auxiliary bolt may be provided in the flange 29 provided at the intake end of the cylinder casing 20, and a screw hole 36' for the auxiliary bolt may be provided on one surface 35a of the flange 35 of the inlet casing 30, and the tip of the auxiliary bolt 81 inserted into the through hole 27' for the auxiliary bolt provided in the flange 29 of the cylinder casing 20 may be screwed into the screw hole 36' for the auxiliary bolt provided in the flange 35 of the inlet casing 30.

[0061] When the auxiliary bolt 81 is attached from the cylinder casing 20 side in this way, it is possible to omit forming a counterbore into which the head of the auxiliary bolt 81 is recessed.

[0062] As described above, the cylinder casing 20 to which the inlet casing 30 is attached is further fastened to the gear casing 40 to complete the casing 10 of the present invention, which consists of the aforementioned cylinder casing 20, inlet casing 30, and gear casing 40.

[0063] The cylinder casing 20 is fastened to the gear casing 40 by fastening the cylinder casing 20 and the gear casing 40 with a fastening bolt 82 through a through hole 38 for the fastening bolt 82 formed in the flange 35 of the inlet casing 30.As a result, when the fastening bolt 82 is tightened, the flange 35 of the inlet casing 30 is clamped between the suction side end face 20a of the cylinder casing 20 and the mounting surface 42 of the gear casing 40, thereby achieving a fastening effect.

[0064] In the example shown in Figure 1, to enable fastening using such a co-fastening bolt 82, a through hole 28 for the co-fastening bolt is provided in the flange 29 provided at the suction end of the cylinder casing 20, a through hole 38 for the co-fastening bolt is provided in the flange of the inlet casing 30, and a screw hole 44' for the co-fastening bolt into which the tip of the co-fastening bolt 82 is screwed is provided in the mounting surface of the gear casing 40, and the tip of the co-fastening bolt 82 inserted into the through holes 28, 38 for the co-fastening bolt from the cylinder casing 20 side is screwed into the screw hole 44' for the co-fastening bolt provided in the mounting surface 42 of the gear casing 40, thereby enabling the cylinder casing 20 with the inlet casing 30 attached to it to be fastened to the gear casing 40.

[0065] In addition, at the fastening point shown in Figure 1, as described above, the tip of the co-tightening bolt 82 inserted into the through holes 28, 38 for the co-tightening bolt from the cylinder casing 20 side is screwed into the screw hole 44' for the co-tightening bolt provided on the mounting surface 42 of the gear casing 40.

[0066] In contrast to this, at another fastening location, as shown in Figure 7, a recess 46 is provided in the gear casing on the back side of the mounting surface 42, thereby forming a bracket 47 having a back surface 42' parallel to the mounting surface 42, and a through hole 44 for the co-fastening bolt that passes through this bracket 47 and a through hole 38 for the co-fastening bolt that passes through the flange 35 of the inlet casing 30 are formed, and a screw hole 28' for the co-fastening bolt is formed in the suction side end face 20a of the cylinder casing 20, and the tip of the co-fastening bolt 82 inserted into the through holes 44, 38 for the co-fastening bolt from the gear casing 40 side is screwed into the screw hole 28' for the co-fastening bolt provided in the suction side end face 20a of the cylinder casing 20, thereby making it possible to fasten the gear casing 40 and the cylinder casing 20 via the inlet casing 30.

[0067] In the embodiment shown in Figure 7, a combination of fastening by inserting a co-tightening bolt 82 from the cylinder casing 20 side and fastening by inserting a co-tightening bolt 82 from the gear casing 40 side is used, but instead of this configuration, it may be modified so that fastening is performed only by a co-tightening bolt 82 inserted from either side.

[0068] In this way, the inlet casing 30 is attached to the cylinder casing 20 in advance using the auxiliary bolts 81, and the cylinder casing 20 and the gear casing 40 are fastened together via the inlet casing 30 using the co-tightening bolts 82. Therefore, when the fastening is achieved using the co-tightening bolts 82, the surface pressure between the cylinder casing 20 and the inlet casing 30 is reinforced not only by the axial force of the co-tightening bolts 82, but also by the axial force of the auxiliary bolts 81 described above. As a result, the number of bolts used can be significantly reduced compared to when the cylinder casing 120 and the inlet casing 130, and the inlet casing 130 and the gear casing 140 are fastened together independently, as in the casing 110 of the conventional screw compressor 100 described with reference to Figure 9.

[0069] As an example, in the conventional casing 110 described with reference to Figure 9, 14 bolts were used to fasten the cylinder casing 120 and the inlet casing 130 together, and 12 bolts were used to fasten the inlet casing 130 and the gear casing 140 together, for a total of 26 bolts, whereas in the casing 10 of the present invention described with reference to Figures 1 to 4 and 7, the casing 10 can be assembled with a total of 13 bolts, including 5 auxiliary bolts and 8 co-fastening bolts.By significantly reducing the number of bolts used, it has been possible to significantly improve workability when assembling the casing 10. [Explanation of symbols]

[0070] 1. Screw compressor 10 Casing 20 Cylinder casing 20a suction side end face (of cylinder casing 20) 21 Rotor Room 22 Refrigerant flow path (oil jacket) 23,24 Shaft hole 25,26 Bearings 27 Screw hole (for auxiliary bolt 81) 27' Through hole (for auxiliary bolt 81) 28 Through hole (for co-tightening bolt 82) 28' screw hole (for co-tightening bolt 82) 29 Flange (of cylinder casing 20) 30 Inlet casing 31,32 Shaft hole 33,34 Bearings 35 Flange (of inlet casing 30) 35a One side (of flange 35) 35b the other surface (of flange 35) 36 Through hole (for auxiliary bolt 81) 36a Reeling 36' screw hole (for auxiliary bolt 81) 37 Boss section 38 Through hole (for co-tightening bolt 82) 40 Gear casing 41 Gear room 42 Mounting surface 42' Rear (mounting surface 42) 43 Fitting hole 44 Through hole (for co-tightening bolt 82) 44' screw hole (for co-tightening bolt 82) 45 Aperture 46 Depression 47 Bracket 50 Male screw rotor 51 Rotor shaft (suction side) 52 Rotor shaft (discharge side) 60 female screw rotor 61 Rotor shaft (suction side) 62 Rotor shaft (discharge side) 71,72 Timing gear 73 Driven gear 74 Drive gear 81 Auxiliary bolt 82 Co-tightening bolt 100 Screw compressor 110 Casing 120 Cylinder casing 120a: Intake end face (of cylinder casing 120) 121 Rotor Room 123,124 Shaft hole 125,126 Bearings 129 flange 130 Inlet casing 131,132 Shaft hole 133,134 Bearings 135 Flange (cylinder casing 120 side) 136 Flange (gear casing 140 side) 140 Gear casing 142 Mounting surface 150 Male screw rotor 151 Rotor shaft (suction side) 152 Rotor shaft (discharge side) 160 female screw rotor 161 Rotor shaft (suction side) 162 Rotor shaft (discharge side) 173 Driven gear 174 Drive gear 183 Bolt (for fastening between cylinder casing and inlet casing) 184 Bolt (for fastening between inlet casing and gear casing)

Claims

1. A casing for a screw compressor comprising: a cylinder casing having a rotor chamber in which a pair of male and female screw rotors are housed so as to be meshed and rotatable; an inlet casing that closes the suction side opening of the rotor chamber provided in the cylinder casing; and a gear casing that houses a driven gear attached to the suction side rotor shaft of either the male or female screw rotor, in mesh with a drive gear to which rotational driving force from a drive source is input, and wherein seal members are provided between the cylinder casing and the inlet casing and between the inlet casing and the gear casing, a flange is provided on the inlet casing, the flange being attached to face an intake end face formed around an intake opening of the rotor chamber of the cylinder casing; auxiliary bolts are provided to attach the flange to the cylinder casing; a casing for a screw compressor, characterized in that, in a state in which the cylinder casing, the inlet casing, and the gear casing are stacked together with the surface of the flange of the inlet casing attached to the cylinder casing opposite the cylinder casing side facing a mounting surface provided on the gear casing, a plurality of co-fastening bolts that fasten the cylinder casing and the gear casing together by passing through through holes provided in the flange of the inlet casing are provided so as to surround the suction side opening of the rotor chamber.

2. a through hole for an auxiliary bolt into which the auxiliary bolt is inserted is provided in the flange of the inlet casing, a threaded hole for an auxiliary bolt into which the auxiliary bolt is screwed is provided in the suction side end surface of the cylinder casing at a position corresponding to the opening position of the through hole for the auxiliary bolt, and the auxiliary bolt is inserted into the through hole for the auxiliary bolt and its tip is screwed into the threaded hole for the auxiliary bolt to attach the inlet casing to the cylinder casing; 2. A casing for a screw compressor according to claim 1, characterized in that a counterbore is provided at the end of the through hole for the auxiliary bolt provided in the flange of the inlet casing on the gear casing side, or a fitting hole is provided in the mounting surface of the gear casing to receive the head of the auxiliary bolt.

3. the screw compressor is an oil-free screw compressor, the cylinder casing has a refrigerant flow path into which a refrigerant is introduced, and the inlet casing is configured to close an intake side opening of the refrigerant flow path, 3. A casing for a screw compressor according to claim 2, characterized in that a portion of a threaded hole for the auxiliary bolt into which the tip of the auxiliary bolt is screwed is provided in the suction side end face of the cylinder casing between the suction side opening of the rotor chamber and the suction side opening of the refrigerant flow path.

4. 2. A casing for a screw compressor according to claim 1, wherein the number of said auxiliary bolts is smaller than the number of said co-fastening bolts.

5. 5. A casing for a screw compressor according to claim 1, wherein the auxiliary bolts are disposed between adjacent ones of the co-fastening bolts.

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