JP7720198B2 - Screw compressor casing - Google Patents

Description

The present invention relates to a casing for a screw compressor, and more specifically to a casing for a screw compressor characterized by a structure in which the various components of the casing are fastened together with bolts.

Figure 8 shows an example of the configuration of the casing 110 of the screw compressor 100, which is shown in Figure 3 of Patent Document 1, which will be discussed later.

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 end face 120a of the cylinder casing 120 with bolts, and a gear casing 140 fastened to the inlet casing 130 on the opposite side of the cylinder casing 120.

The cylinder casing 120 is provided with a rotor chamber 121 that rotatably houses a pair of male and female screw rotors 150, 160. Of the rotor shafts 151, 152; 161, 162 provided on the pair of screw rotors 150, 160, shaft holes 123, 124 that house the discharge-side rotor shafts 152, 162 are formed in a portion of the cylinder casing 120 located on the discharge side of the rotor chamber 121. Shaft holes 131, 132 that house the suction-side rotor shafts 151, 161 are formed in the inlet casing 130.

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

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. By meshing the driven gear 173 with the drive gear 174 within the gear casing 140, the pair of male and female screw rotors 150, 160 can be rotated in mesh by operating the driving source (not shown).

As described above, in the casing 110 of the screw compressor 100, which consists of the cylinder casing 120, inlet casing 130, and gear casing 140, the cylinder casing 120 and the inlet casing 130 are fastened together by aligning the suction end face 120a of the cylinder casing 120 and the cylinder casing 120-side end face of the inlet casing 130, and then aligning the flange 129 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.

The inlet casing 130 and the gear casing 140 are connected by aligning the end face of the inlet casing facing the gear casing 140 and the mounting surface 142 of the gear casing 140, and the flange 136 on the gear casing 140 side of the inlet casing 130 is fastened to the gear casing 140 with bolts 184.

To assemble the screw compressor 100 equipped with the casing 110 configured in this manner, first, the pair of male and female screw rotors 150, 160 are placed inside the rotor chamber 121 of the cylinder casing 120. Then, the inlet casing 130 is used to close the suction side opening of the rotor chamber 121 in the cylinder casing 120, and necessary components such as bearings 125, 126, 133, and 134 are attached. Then, bolts 183 are inserted into the through holes in the flange 129 of the cylinder casing 120, and the tips of the bolts 183 are screwed into the threaded holes 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.

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 threaded hole provided in the mounting surface 142 of the gear casing 140, thereby fastening the inlet casing 130 and gear casing 140 together.

JP 2009-243281 A

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

In addition, 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 and 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, resulting in a long assembly time.

Furthermore, since the inlet casing 130 is fastened to the gear casing 140 by inserting and tightening bolts 184 from the inlet casing 130 side toward the gear casing 140 side, it is necessary to secure 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 so that the bolts 184 can be inserted into through holes provided in the flange 136 and a fastening tool can be accommodated to tighten 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.

The present invention was made to overcome the drawbacks of the above-mentioned conventional technology, and aims to improve workability during assembly of the screw compressor casing 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, despite a relatively simple configuration. A further aim is to provide a screw compressor casing 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.

Below, the means for solving the problems are described along 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 intended to limit the interpretation of the technical scope of the present invention.

In order to achieve the above object, the casing 10 of the screw compressor 1 of the present invention is
A casing (10) of a screw compressor (1) comprising: 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 an intake 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 an intake 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 an intake side end surface 20a formed around the intake 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 the cylinder casing 20, the inlet casing 30, and the gear casing 40 are stacked together, and a plurality of co-fastening bolts 82 that fasten the cylinder casing 20 and the gear casing 40 through through holes (through holes 38 for co-fastening bolts) provided in the flange 35 of the inlet casing 30 are provided so as to surround the intake side opening of the rotor chamber 21 (claim 1).

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 threaded 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 end is screwed into the threaded 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 (FIG. 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 FIG. 1) (claim 2).

As described 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 in the suction side end surface 20 a of the cylinder casing 20 to attach the inlet casing 30 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 threaded 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).

The number of auxiliary bolts 81 may be less than the number of co-fastening bolts 82 (Claim 4).

Furthermore, the auxiliary bolts 81 may be placed between each of the adjacent co-fastening bolts 82, 82 (Claim 5).

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:

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 achieved by the cooperation of the auxiliary bolts 81 and the co-fastening bolts 82 used to fasten the cylinder casing 20 with the inlet casing 30 attached to the gear casing 40. This reduces 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 inlet casing 130, and the inlet casing 130 and gear casing 140 are each fastened separately at two locations.

As a result, workability during assembly of the casing 10 has been significantly improved.

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 inlet casing 30 can be fastened together at a higher surface pressure than the surface pressure between the inlet casing 30 and gear casing 40, which is applied only by the axial force of the co-tightening bolt 82. This prevents the compressed gas in the rotor chamber 21 from leaking outside the machine, and, if an oil jacket 22 (described below) is provided, prevents the cooling oil in the oil jacket 22 from leaking outside the machine or into the rotor chamber 21.

In addition, with the conventional casing 110 structure 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 provide space S behind the flange 136 provided at the end of the inlet casing 130 facing the gear casing 140, which was necessary for operating a fastening tool. To provide this space S, the overall length of the inlet casing 130 in the axial direction of the rotor shafts 151 and 161 was increased. However, with the configuration of the present invention, it is not necessary to provide such space S. As a result, the overall length of the inlet casing 30 in the axial direction of the rotor shafts 51 and 61 can be shortened, thereby achieving a smaller and lighter casing 10 and, ultimately, a smaller and lighter screw compressor 1.

When the casing 10 of the present invention is used as the casing for 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 threaded hole 27 for the auxiliary bolt, into which the tip of the auxiliary bolt 81 is threaded, 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. This increases 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.

Furthermore, by reducing the number of auxiliary bolts 81 compared to the number of co-fastening bolts 82, the total number of bolts used in assembling the casing 10 is significantly reduced, further improving workability when assembling the casing 10. However, 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-fastening 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.

Furthermore, in a configuration in which the auxiliary bolts 81 are placed between adjacent co-fastening bolts 82, 82, the bolt installation pitch is shortened, improving the surface pressure between the cylinder casing 20 and the inlet casing 30, making it possible to withstand use in screw compressors 1 used under more severe conditions, such as screw compressors used to generate high-pressure compressed gas.

1 is a cross-sectional plan view of a screw compressor equipped with a casing of the present invention. 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. FIG. 2 is a view of the cylinder casing from the intake end face side. FIG. 10 is a view of the inlet casing from the mating surface side with the gear casing. FIG. 1 is a view of the cylinder casing (without a refrigerant flow path) viewed from the suction end face side. 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 the screw hole 27 for the auxiliary bolt is changed compared to FIG. 5 ). FIG. 2 is a plan view of the assembled casing of the present invention. 1 is a cross-sectional plan view of a screw compressor equipped with a conventional casing (corresponding to FIG. 3 of Patent Document 1). FIG. 1 is a cross-sectional plan view of a screw compressor equipped with a conventional casing.

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

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

The cylinder casing 20 has a rotor chamber 21 that rotatably houses a pair of male and female screw rotors 50, 60. The male screw rotor 50 and the female screw rotor 60 mesh and rotate within this rotor chamber 21, compressing the gas to be compressed.

The pair of male and female screw rotors 50, 60 housed in the rotor chamber 21 each have a rotor shaft 51, 52, 61, 62 protruding from each end, which serves as a rotating shaft. The inlet casing 30, which closes the suction side opening of the cylinder casing 20, is provided with shaft 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 shaft holes 31, 32.

Meanwhile, the cylinder casing 20, in a portion located closer to the discharge side than the rotor chamber 21, has shaft holes 23, 24 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 shaft holes 23, 24.

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 through the non-contact meshing 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. In order to enable the pair of male and female screw rotors 50, 60 to mesh and rotate 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.

Of the shaft holes 31, 32 provided in the inlet casing 30, the shaft 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 shaft hole 31 into the gear chamber 41 formed in the gear casing 40.

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 inside 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 manner by operating the drive source.

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

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

Assembly of the casing 10 begins with attaching the inlet casing 30 to the cylinder casing 20 configured as described above.

Then, the cylinder casing 20 with the inlet casing 30 attached is fastened to the gear casing 40, thereby assembling the casing 10 of the present invention, which consists of the cylinder casing 20, inlet casing 30, and gear casing 40.

When installing the inlet casing 30, a pair of male and female screw rotors 50, 60 are first installed inside the rotor chamber 21 of the cylinder casing 20. In this state, the inlet casing 30 seals the intake side openings of the rotor chamber 21 and oil jacket 22 of the cylinder casing 20 via sealing members such as O-rings, gaskets, or liquid gaskets (O-rings in the illustrated example). This prevents compressed gas from inside the rotor chamber 21 from leaking outside the machine, and also prevents cooling oil from inside the oil jacket 22 from leaking outside the machine or into the rotor chamber 21. This also allows necessary equipment, such as bearings 25, 26, 33, and 34, to be installed in the shaft holes 23 and 24 of the inlet casing 30.

The inlet casing 30 is provided with a flange 35 to enable attachment to the cylinder casing 20. 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 can close the suction side openings of the rotor chamber 21 and oil jacket 22 provided in the cylinder casing 20.

The flange 35 of the inlet casing 30 also has a second surface 35b that faces the mounting surface 42 provided on the gear casing 40.

In this embodiment, as shown in Figure 4, a boss portion 37 that extends the axial holes 31, 32 toward the gear casing 40 is provided on the end face of the inlet casing 30 on the fastening side with the gear casing 40, and an opening 45 that receives this boss portion 37 is formed in the side wall of the gear casing 40. 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 aligned opposite the mounting surface 42 formed on the periphery of the opening 45.

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, preventing 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.

Attaching the inlet casing 30 to the cylinder casing 20, which is an intermediate step in assembling the casing 10, is performed using auxiliary bolts 81, as shown in Figures 1 and 7.

The attachment of the inlet casing 30 to the cylinder casing 20 with the auxiliary bolts 81, which is performed during the intermediate step of assembling the casing 10, does not necessarily need to generate the surface pressure required when the screw compressor 1 is finally assembled. It is sufficient that when the inlet casing 30 and the cylinder casing 20 are fastened to the gear casing 40 with the co-fastening bolts 82 described below, the axial force of the co-fastening bolts 82 is supplemented by the axial force of the auxiliary bolts 81 to obtain the required surface pressure.

To enable the inlet casing 30 to be attached to the cylinder casing 20 using this auxiliary bolt 81, in the illustrated example, an auxiliary bolt through-hole 36 is provided in the flange 35 of the inlet casing 30 for inserting the auxiliary bolt 81.

Then, the tip of the auxiliary bolt 81 inserted into this auxiliary bolt through hole 36 from the gear casing 40 side is screwed into the auxiliary bolt threaded hole 27 provided on the suction side end face 20a of the cylinder casing 20, thereby enabling the inlet casing 30 to be attached to the suction side end face 20a of the cylinder casing 20.

In this configuration, the inlet casing 30 is attached to the cylinder casing 20 using auxiliary bolts 81 inserted from the gear casing 40 side into the auxiliary bolt through holes 36 provided in the flange 35 of the inlet casing 30. When fastening the cylinder casing 20 with the attached inlet casing 30 to the gear casing 40 in this manner, a counterbore 36a is provided at the end of the auxiliary bolt through hole 36 on the gear casing 40 side, allowing the head of the auxiliary bolt 81 to be recessed into this counterbore 36a, so that the head of the auxiliary bolt 81 does not interfere with the mounting surface 42 of the gear casing 40.

In order 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 may be formed at a corresponding position on the mounting surface 42 of the gear casing 40 (see "Variation 1" in Figure 1). With this configuration, 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 easy to align the inlet casing 30 to the specified mounting position.

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, some of the threaded holes 27 for auxiliary bolts provided on the suction end face 20a of the cylinder casing 20 are located between the rotor chamber 21 and the oil jacket 22, and the flange 35 of the inlet casing 30 is provided with the aforementioned through-holes 36 for auxiliary bolts at positions corresponding to these threaded holes 27 for auxiliary bolts. The threaded holes 27 and through-holes 36 for auxiliary bolts can be used to attach the inlet casing to the cylinder casing with the aforementioned auxiliary bolts 81.

In this way, by providing a threaded hole 27 for an auxiliary bolt between the rotor chamber 21 and the oil jacket 22 and attaching an auxiliary bolt 81, it is possible to increase the surface pressure between the portion of the suction end surface 20a of the cylinder casing 20 between the rotor chamber 21 and the oil jacket 22 and one surface 35a of the flange 35 of the inlet casing 30, thereby making it difficult for the cooling oil in the oil jacket 22 to leak toward the rotor chamber 21.

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 periphery of the suction end face 20a of the cylinder casing 20, and through holes 36 for auxiliary bolts may be provided on the periphery of the flange 35 of the inlet casing 30 at the positions where the threaded holes 27 for auxiliary bolts are formed, thereby attaching the inlet casing 30 to the cylinder casing 20.

In this case, as shown in Figure 5, the number of threaded holes 27 for auxiliary bolts formed on the suction 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).

Furthermore, 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, threaded holes 27 for auxiliary bolts may be formed between the through holes 28 or threaded holes 28' for the co-fastening bolts formed at the mounting positions of the co-fastening bolts 82 described below, as shown in Figure 6, and auxiliary bolts 81 may be arranged between adjacent co-fastening bolts 82.

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 inserting the auxiliary bolt 81 into the auxiliary bolt through hole 36 from the gear casing 40 side and threading the tip of the auxiliary bolt into the auxiliary bolt threaded hole 27 provided on the suction side end face 20a of the cylinder casing 20.

However, the attachment of the inlet casing 30 to the cylinder casing 20 is not limited to this configuration. Instead of or in combination with the above configuration, as shown in "Variation 2" in Figure 1, a through hole 27' for the auxiliary bolt may be formed in the flange 29 provided at the intake end of the cylinder casing 20, and a threaded hole 36' for the auxiliary bolt may be formed on one surface 35a of the flange 35 of the inlet casing 30. 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 can then be screwed into the threaded hole 36' for the auxiliary bolt provided in the flange 35 of the inlet casing 30.

When the auxiliary bolt 81 is attached from the cylinder casing 20 side in this way, it is possible to omit forming a counterbore for the head of the auxiliary bolt 81 to be recessed.

As described above, the cylinder casing 20 with the inlet casing 30 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.

The cylinder casing 20 is fastened to the gear casing 40 by fastening the cylinder casing 20 and 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. When the fastening bolt 82 is tightened, the flange 35 of the inlet casing 30 is clamped between the suction end surface 20a of the cylinder casing 20 and the mounting surface 42 of the gear casing 40, resulting in a fastening arrangement.

In the example shown in Figure 1, to enable fastening using such a fastening bolt 82, a through hole 28 for the fastening bolt is provided in the flange 29 at the intake end of the cylinder casing 20, a through hole 38 for the fastening bolt is provided in the flange of the inlet casing 30, and a threaded hole 44' for the fastening bolt into which the tip of the fastening bolt 82 is threaded is provided in the mounting surface of the gear casing 40. The tip of the fastening bolt 82 is inserted into the through holes 28, 38 for the fastening bolt from the cylinder casing 20 side and threaded into the threaded hole 44' for the fastening bolt provided in the mounting surface 42 of the gear casing 40, thereby fastening the cylinder casing 20 with the inlet casing 30 attached to it to the gear casing 40.

In the fastening location shown in Figure 1, as described above, the tip of the fastening bolt 82 inserted into the fastening bolt through-holes 28, 38 from the cylinder casing 20 side is screwed into the fastening bolt threaded hole 44' provided on the mounting surface 42 of the gear casing 40.

In contrast, at another fastening location, as shown in Figure 7, a recess 46 can be formed in the gear casing on the back side of the mounting surface 42, forming a bracket 47 with a back surface 42' parallel to the mounting surface 42. A through hole 44 for the fastening bolt can be formed through this bracket 47, and a through hole 38 for the fastening bolt can be formed through the flange 35 of the inlet casing 30. A threaded hole 28' for the fastening bolt can also be formed in the suction side end face 20a of the cylinder casing 20. The tip of a fastening bolt 82 inserted into the through holes 44, 38 for the fastening bolt from the gear casing 40 side can then be threaded into the threaded hole 28' for the fastening bolt provided in the suction side end face 20a of the cylinder casing 20, thereby fastening the gear casing 40 and cylinder casing 20 via the inlet casing 30.

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

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

As an example, the conventional casing 110 described with reference to Figure 9 required 14 bolts to fasten the cylinder casing 120 and inlet casing 130 together, and 12 bolts to fasten the inlet casing 130 and gear casing 140 together, for a total of 26 bolts. In contrast, the casing 10 of the present invention described with reference to Figures 1 to 4 and 7 can be assembled with a total of 13 bolts, including five auxiliary bolts and eight co-fastening bolts. This significant reduction in the number of bolts used has significantly improved workability when assembling the casing 10.

1 Screw compressor 10 Casing 20 Cylinder casing 20a Suction side end surface (of cylinder casing 20)
21 rotor chamber 22 refrigerant flow path (oil jacket)
23, 24 Shaft holes 25, 26 Bearing 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 holes 33, 34 Bearing 35 Flange (of inlet casing 30)
35a One surface (of flange 35)
35b the other surface (of the flange 35)
36 Through hole (for auxiliary bolt 81)
36a Counterbore 36' Screw hole (for auxiliary bolt 81)
37 Boss portion 38 Through hole (for co-tightening bolt 82)
40 Gear casing 41 Gear chamber 42 Mounting surface 42' Back surface (of mounting surface 42)
43 Fitting hole 44 Through hole (for co-fastening bolt 82)
44' Screw hole (for co-tightening bolt 82)
45 Opening 46 Recess 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-fastening bolt 100 Screw compressor 110 Casing 120 Cylinder casing 120a Intake side end face (of cylinder casing 120)
121 Rotor chamber 123, 124 Shaft holes 125, 126 Bearing 129 Flange 130 Inlet casing 131, 132 Shaft holes 133, 134 Bearing 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 (5)

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 . 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. 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. A screw compressor casing as described in claim 1, characterized in that the number of auxiliary bolts is less than the number of co-fastening bolts. 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.