JP6767948B2 - Oil-cooled two-stage screw compressor - Google Patents

Description

The present invention relates to an oil-cooled two-stage screw compressor.

In some oil-cooled two-stage screw compressors, the first-stage screw rotor and the second-stage screw rotor are coupled by a coupling. In such an oil-cooled two-stage screw compressor, the distance between the first-stage and second-stage screw rotors is longer than that of the shaft-integrated type in order to provide the coupling. Bearings are required to support both ends of the second stage screw rotor. For example, Patent Document 1 discloses an oil-cooled two-stage screw compressor including a coupling and bearings that support both ends of the first-stage and second-stage screw rotors.

Japanese Unexamined Patent Publication No. 2014-74350

An oil-cooled two-stage screw compressor equipped with a coupling and bearings that support both ends of the first and second stage screw rotors has three rotor casings that house the screw rotors for assembly. A structure for dividing into the above is required. That is, a coupling and a bearing are provided between the first compression chamber accommodating the first stage screw rotor, the second compression chamber accommodating the second stage screw rotor, and the first compression chamber and the second compression chamber. A divided structure for forming each of the intermediate chambers to be provided is required. However, such a split structure of the rotor casing requires high-precision machining of the split surface, which increases the man-hours for assembling and is one of the factors for increasing the manufacturing cost. Therefore, in order to reduce the manufacturing cost, it is necessary to form a rotor casing having a simple structure.

An object of the present invention is to provide an oil-cooled two-stage screw compressor having a simplified rotor casing structure.

The present invention includes a first rotor set having a first driven side rotor and a first driven side rotor, a second rotor set having a second driven side rotor and a second driven side rotor, and the first driven. The connection portion that mechanically connects the side rotor and the second drive side rotor, the first compression chamber that houses the first rotor set, and the first compression chamber are fluidly communicated with the second rotor. The rotor casing includes a rotor casing that forms a second compression chamber for accommodating the set, the rotor casing has an intermediate wall that separates the first compression chamber and the second compression chamber, and the connection portion is the connection portion. A connection shaft formed in either the first drive side rotor or the second drive side rotor, a connection hole formed in the other and fitting the connection shaft coaxially, and a relative relationship between the connection shaft and the connection hole. The intermediate wall has a rotation prevention structure for preventing such rotation, and the intermediate wall has a through hole for inserting the connection shaft and a first intermediate bearing that pivotally supports the first driven side rotor. An oil-cooled type having a first recess for installing from the compression chamber side and a second recess for installing the second intermediate bearing that pivotally supports the second driven side rotor from the second compression chamber side. A two-stage screw compressor is provided.

According to this configuration, the structure of the rotor casing is simplified by devising the structure of the intermediate wall. Specifically, since a through hole is provided in the intermediate wall, the connection shaft connecting the first drive side rotor and the second drive side rotor can be guided through the through hole, and the first drive side rotor and the second drive side can be guided. The connection with the rotor can be easily secured. Further, since the first recess is provided in the intermediate wall, the first intermediate bearing can be installed together with the first driven side rotor from the first compression chamber side, and the second recess is provided in the intermediate wall. 2 The intermediate bearing can be installed from the second compression chamber side together with the second driven side rotor. In other words, the first intermediate bearing and the first driven rotor can be installed from the same one side with respect to the intermediate wall, and similarly, the second intermediate bearing and the second driven rotor are the same with respect to the intermediate wall. It can be installed from the other side. Therefore, the necessary parts can be easily installed in the rotor casing, and the structure of the rotor casing can be simplified. Further, in the above configuration, the first drive side rotor and the second drive side rotor are connected by a connecting portion without providing a coupling. As a result, it is not necessary to provide an intermediate chamber for installing the coupling, so that the structure of the rotor casing can be simplified.

The first drive-side rotor may be a male screw rotor, and the second drive-side rotor may also be a male screw rotor.

According to this configuration, in both the first rotor set and the second rotor set, the male screw rotor is driven and the power is transmitted to the female screw rotor. Comparing the case where power is transmitted from the male screw rotor to the female screw rotor and the case where power is transmitted from the female screw rotor to the male screw rotor, the transmission torque is smaller in the former case. .. Specifically, the number of teeth on the male screw rotor is generally less than the number of teeth on the female screw rotor. Therefore, when the male screw rotor makes one rotation, the female screw rotor rotates less than one rotation. That is, when power is transmitted from the male screw rotor to the female screw rotor, the transmission torque can be reduced as described above because the gear ratio is less than 1. Therefore, since the required power can be reduced, the load applied to the first rotor set and the second rotor set is reduced, and the tooth surface strength required for the first rotor set and the second rotor set is also lowered. In other words, the durability of the first rotor set and the second rotor set can be improved.

The first drive-side rotor may be a female screw rotor, and the second drive-side rotor may also be a female screw rotor.

According to this configuration, power is transmitted from the female screw rotor to the male screw rotor in both the first rotor set and the second rotor set. From the viewpoint of the gear ratio, when power is transmitted from the female screw rotor to the male screw rotor, the gear ratio is 1 or more. Therefore, since the rotation speeds of the first rotor set and the second rotor set can be increased, the discharge air volume at the same rotation speed can be increased as compared with the case of driving the male rotor.

One of the first drive side rotor and the second drive side rotor is inserted to insert a fixing screw for fixing the axial relative position between the first drive side rotor and the second drive side rotor. It may have a hole, and the other may have a screw fastening portion adjacent to the insertion hole for fastening the fixing screw.

According to this configuration, since the relative positions of the first drive-side rotor and the second drive-side rotor in the axial direction are fixed by the fixing screws, the thrust forces generated in these are common. Therefore, when a bearing that supports this common thrust force is provided, the bearing can be shared, so that the structure can be simplified.

The first rotor set and the second rotor set so that the compression action in the first compression chamber and the second compression chamber produces a pressing force that presses the first rotor set and the second rotor set in the same axial direction. A second rotor set is provided,
A thrust bearing capable of supporting at least a thrust load and a force resisting the pressing force are applied to the second drive side rotor at an end opposite to the connection portion with respect to the second drive side rotor. It may further be provided with a balance piston for this purpose.

According to this configuration, by providing the balance piston, the reaction force due to the discharge pressure generated in the first drive side rotor and the second drive side rotor can be reduced. Therefore, the thrust force applied to the thrust bearing is reduced, so that the thrust bearing can be miniaturized.

The second compression chamber may be arranged after the first compression chamber, the insertion hole may be provided in the second drive side rotor, and the screwing portion may be provided in the first drive side rotor. ..

According to this configuration, the insertion hole can be easily formed. In general, the second rotor set in the rear stage has a smaller diameter and a shorter length than the first rotor set in the front stage. Therefore, from the viewpoint of the amount of processing for forming the insertion hole, the amount of processing for the second rotor set in the subsequent stage is smaller than that in the first rotor set in the previous stage, so that the insertion hole can be easily formed.

The diameter of the through hole is smaller than the diameter of the tooth bottom of the first drive side rotor and smaller than the diameter of the tooth bottom of the second drive side rotor, and one end of the through hole is on the first drive side. A part of the end portion of the rotor has entered, and a part of the end portion of the second drive side rotor has entered the other end portion of the through hole, so that the edge portion of the through hole and the edge portion thereof A seal region may be formed between the tooth bottom of the first drive side rotor and the tooth bottom of the second drive side rotor.

According to this configuration, the seal region forms a shaft seal for the through hole. Therefore, since it is possible to prevent fluid from leaking from the through holes in the first compression chamber and the second compression chamber, the performance of the oil-cooled two-stage screw compressor can be improved.

The diameter of the first recess is smaller than the diameter of the tooth bottom of the first driven rotor, and a part of the end portion of the first driven rotor has entered the first recess. A seal region is formed between the edge of the first recess and the tooth bottom of the first driven rotor, and the diameter of the second recess is the diameter of the tooth bottom of the second driven rotor. It is smaller, and a part of the end portion of the second driven side rotor has entered the second recess, so that the edge portion of the second recess and the tooth bottom of the second driven side rotor A seal region may be formed between and.

According to this configuration, a shaft seal is formed for each of the first recess and the second recess by the seal region. Therefore, the leakage of the fluid from the first compression chamber to the first recess and the leakage of the fluid from the second compression chamber to the second recess can be prevented, so that the performance of the oil-cooled two-stage screw compressor can be improved. ..

The rotor casing is made of an integral casting, and has a first opening into which the first rotor set can be inserted from the outside of the first compression chamber into the inside of the first compression chamber toward the intermediate wall. A second opening into which the second rotor set can be inserted from the outside of the second compression chamber to the inside of the second compression chamber toward the intermediate wall may be provided at both ends.

According to this configuration, since the rotor casing is formed of an integral casting without providing a dividing surface on the rotor casing, the man-hours for processing and assembling the rotor casing can be reduced. Further, since the first rotor set and the second rotor set can be inserted through the openings at both ends of the rotor casing, the first rotor set and the second rotor set can be easily arranged in the rotor casing.

The male screw rotor of the first rotor set has a four-toothed shape, and the female screw rotor of the first rotor set has a six-toothed shape.
The male screw rotor of the second rotor set may have a five-toothed shape, and the female screw rotor of the second rotor set may have a six-toothed shape.

According to this configuration, the diameter of the tooth bottom of the first drive side rotor and the diameter of the tooth bottom of the second drive side rotor can be brought close to each other. In the case of a structure in which the connection shaft is passed through the through hole as described above, the diameters of both ends of the through hole are made the same by bringing the diameter of the tooth bottom of the first drive side rotor and the diameter of the tooth bottom of the second drive side rotor close to each other. Can be about. Therefore, a through hole can be easily formed. In particular, when the first rotor set has a so-called 4-6 tooth profile and the second rotor set has a so-called 5-6 tooth profile, the diameter of the tooth bottom of the first drive side rotor and the diameter of the tooth bottom of the second drive side rotor are substantially defined. Can be about the same.

According to the present invention, in the oil-cooled two-stage screw compressor, the necessary parts can be easily installed in the rotor casing by providing the through hole, the first recess and the second recess in the intermediate wall. The structure of the rotor casing can be simplified.

Horizontal sectional view of the oil-cooled two-stage screw compressor according to the embodiment of the present invention. Sectional view of the first rotor set Sectional view of the second rotor set Schematic cross-sectional view near the anti-rotation structure for power transmission Vertical sectional view of the oil-cooled two-stage screw compressor according to the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a horizontal sectional view of a compressor (oil-cooled two-stage screw compressor) 1 according to an embodiment. The compressor 1 has a low-stage compression unit 10 that compresses a gas sucked from the outside and a high-stage compression unit 20 that further compresses the gas compressed by the low-stage compression unit 10, and a screw rotor is used as described later. It is a two-stage screw compressor for use. Further, the compressor 1 is an oil-cooled type, and the oil is used for lubrication of each part of the compressor 1 and also acts as a coolant for removing heat generated during compression.

The low-stage compression unit 10 has a first compression chamber 12 defined by a rotor casing 30 and a bearing casing 50. A pair of male and female first rotor sets 13 is housed in the first compression chamber 12. Specifically, the first rotor set 13 includes a first male rotor (first drive side rotor) 14 which is a male screw rotor and a first female rotor (first driven rotor) which is a female screw rotor. It is composed of a side rotor) 15. When the first male rotor 14 and the first female rotor 15 rotate in a meshed state, the compressor 1 takes in gas, compresses it, and discharges it toward the high-stage compression unit 20.

FIG. 2 is a cross-sectional view of the first rotor set 13. In the present embodiment, the first male rotor 14 has a four-toothed shape, and the first female rotor 15 has a six-toothed shape. Therefore, when the first male rotor 14 makes one rotation, the first female rotor 15 makes two-thirds of the rotation. The material of the first rotor set 13 is not particularly limited, but is preferably a metal having a tooth surface strength required to rotate without being damaged in the meshed state, and is, for example, steel. In FIG. 2, only the inner shape of the rotor casing 30 is shown.

As shown in FIG. 1, the high-stage compression unit 20 has a second compression chamber 22 defined by a rotor casing 30 and a bearing casing 70. A pair of male and female second rotor sets 23 are housed in the second compression chamber 22. Specifically, the second rotor set 23 includes a second male rotor (second drive side rotor) 24 which is a male screw rotor and a second female rotor (second driven rotor) which is a female screw rotor. It is composed of a side rotor) 25. In particular, the second rotor set 23 is formed to have a smaller diameter and a shorter length than the first rotor set 13. By rotating the second male rotor 24 and the second female rotor 25 in a meshed state, the compressor 1 further compresses the compressed gas supplied from the low-stage compression unit 10 and discharges it to the outside.

FIG. 3 is a cross-sectional view of the second rotor set 23. In the present embodiment, the second male rotor 24 has a five-toothed shape, and the second female rotor 25 has a six-toothed shape. Therefore, when the first male rotor 14 makes one rotation, the first female rotor 15 makes 5/6 rotations. The material of the second rotor set 23 is not particularly limited, but is preferably a metal having a tooth surface strength required to be able to rotate without being damaged in the meshed state, and is, for example, steel. In FIG. 3, only the inner shape of the rotor casing 30 is shown.

As shown in FIG. 1, rotor shafts 14a, 14b, 15a, 15b, 24a, 24b, 25a, 25b extend from the ends of the rotors 14, 15, 24, 25, respectively. Bearings 16-18, 26-28 are attached to the rotor shafts 14b, 15a, 15b, 24a, 25a, 25b, respectively, and the rotor shafts 14b, 15a, 15b, 24a are attached by the bearings 16-18, 26-28. , 25a, 25b are axially supported, respectively.

The bearing 16 attached to the rotor shaft 14b extending from the low pressure side (right side in the figure) of the first male rotor 14 is a radial bearing (roller bearing) capable of supporting a radial load. The bearing 26 attached to the rotor shaft 24a extending from the high pressure side (left side in the drawing) of the second male rotor 24 is a thrust bearing (ball bearing) capable of supporting at least a thrust load. A balance piston 76 is also attached to the rotor shaft 24a. The balance piston 76 applies a force to the rotor shaft 24a against the thrust force (pushing pressure) commonly acting on the first male rotor 14 and the second male rotor 24 by utilizing the pressure of the lubricating oil. Can be done. That is, the balance piston 76 can reduce the thrust force received by the bearing 26 attached to the rotor shaft 24a.

The bearing 18 attached to the rotor shaft 15b extending from the low pressure side (right side in the figure) of the first female rotor 15 is a thrust bearing (ball bearing) capable of supporting at least a thrust load. Further, the bearing 17 attached to the rotor shaft 15a extending from the high pressure side (left side in the drawing) of the first female rotor 15 is a radial bearing (roller bearing) capable of supporting a radial load.

The bearing 28 attached to the rotor shaft 25b extending from the low pressure side (right side in the figure) of the second female rotor 25 is a radial bearing (roller bearing) capable of supporting a radial load. Further, the bearing 27 attached to the rotor shaft 25a extending from the high pressure side (left side in the drawing) of the second female rotor 25 is a thrust bearing (ball bearing) capable of supporting at least a thrust load.

A connection hole for fitting the rotor shaft (connection shaft) 24b extending from the low pressure side (right side in the figure) of the second male rotor 24 into the rotor shaft 14a extending from the high pressure side (left side in the figure) of the first male rotor 14. 14c is provided. Therefore, the first male rotor 14 and the second male rotor 24 are mechanically connected by fitting the rotor shaft 24b coaxially into the connection hole 14c. Therefore, the first male rotor 14 and the second male rotor 24 are arranged so as to extend in the coaxial direction. Further, a rotation prevention structure 41 is provided between the rotor shaft 24b and the connection hole 14c to prevent the relative rotation of the rotor shaft 24b and the connection hole 14c.

FIG. 4 is a schematic cross-sectional view of the vicinity of the rotation prevention structure 41 for power transmission. The rotation prevention structure 41 is formed by inserting a key member 44 attached to a key groove 42 provided in the rotor shaft 24b into a key groove 43 provided in the connection hole 14c. In the present embodiment, the rotor shaft 24b, the connection hole 14c, and the rotation prevention structure 41 constitute a connection portion 40 that mechanically connects the first male rotor 14 and the second male rotor 24. .. However, the mode of the connecting portion 40 is not limited to that of the present embodiment. For example, the rotor shaft 14a of the first male rotor 14 is used as the connecting shaft, and the connecting hole into which the connecting shaft is fitted is the second male rotor 24. It may be provided on the rotor shaft 24b of the above. That is, the rotor shaft 24b may be configured to hold the rotor shaft 14b. Further, as another aspect of the connecting portion 40, the connecting hole 14c does not necessarily have to be provided in the rotor shaft 14a. For example, the first male rotor 14 does not have the rotor shaft 14a, and the first male rotor 14 does not have the rotor shaft 14a. A connection hole may be provided directly in the main body of the mold rotor 14. According to this, the diameter of the rotor shaft 24b of the second male rotor 24 can be increased to increase the rigidity of the connecting portion.

As shown in FIG. 1, the rotor casing 30 is made of an integral casting and has an intermediate wall 31 inside which separates the first compression chamber 12 and the second compression chamber 22. The rotor casing 30 has a first opening 35 at one end into which the first rotor set 13 can be inserted from the outside of the first compression chamber 12 into the inside of the first compression chamber 12 toward the intermediate wall 31. The other end has a second opening 36 into which the second rotor set 23 can be inserted from the outside of the compression chamber 22 into the inside of the second compression chamber 22 toward the intermediate wall 31. That is, the rotor casing 30 has a tubular shape with both ends open.

As shown together with FIGS. 1 to 3, the intermediate wall 31 has a through hole 32 for inserting the rotor shaft 24b. The diameter R0 of the through hole 32 is smaller than the diameter R1 of the tooth bottom of the first male rotor 14 and smaller than the diameter R2 of the tooth bottom of the second male rotor 14. As a result, seal regions S1 and S2 are formed between the edge of the through hole 32 and the tooth bottom of the first male rotor 14 and the tooth bottom of the second male rotor 24, respectively. Further, a part of the end portion of the first male rotor 14 has entered the one end portion of the through hole 32 (see the shaded portion in the enlarged circle C1 in FIG. 1), and the other end portion of the through hole 32. A part of the end portion of the second male rotor 24 has entered (see the shaded portion in the enlarged circle C2 in FIG. 1).
The distance between the approaching portion at the end of the first male rotor 14 and the inner wall of the through hole 32 is set to about 0.05 mm, and similarly, with the approaching portion at the end of the second male rotor 24. The distance between the through hole 32 and the inner wall is set to about 0.05 mm. Therefore, a seal region is formed even in these 0.05 mm gaps.

As shown in FIG. 1, the intermediate wall 31 has a first recess 33 and a second recess 33 for installing a bearing (first intermediate bearing) 17 that pivotally supports the first female rotor 15 from the first compression chamber 12 side. It has a second recess 34 for installing a bearing (second intermediate bearing) 28 that pivotally supports the female rotor 25 from the second compression chamber 22 side. The first recess 33 is a recess provided on the surface of the intermediate wall 31 on the side of the first compression chamber 12 and has a diameter slightly larger than that of the bearing 17 and is formed to a depth sufficient to install the bearing 17. .. The second recess 34 is a recess provided on the surface of the intermediate wall 31 on the side of the second compression chamber 22 and has a diameter slightly larger than that of the bearing 28 and is formed to a depth sufficient to install the bearing 28. ..

As shown together with FIGS. 1 to 3, the diameter r10 of the first recess 33 is smaller than the diameter r11 of the tooth bottom of the first female rotor 15. As a result, the seal region S11 is formed between the edge of the first recess 33 and the tooth bottom of the first female rotor 15. Further, a part of the end portion of the first female rotor 15 has entered the first recess 33 (see the shaded portion in the enlarged circle C3 in FIG. 1), and the end portion of the first female rotor 15 The distance between the approach portion and the inner wall of the first recess 33 is set to about 0.05 mm. Therefore, a seal region is formed even in this 0.05 mm gap. Similarly, the diameter r20 of the second recess 34 is smaller than the diameter r21 of the tooth bottom of the second female rotor 25. As a result, the seal region S21 is formed between the edge of the second recess 34 and the tooth bottom of the second female rotor 25. Further, a part of the end portion of the second female rotor 25 has entered the second recess 34 (see the shaded portion in the enlarged circle C4 in FIG. 1), and the end portion of the second female rotor 25 The distance between the approach portion and the inner wall of the second recess 34 is set to about 0.05 mm. Therefore, a seal region is formed even in this 0.05 mm gap.

As shown in FIG. 1, the intermediate wall 31 of the rotor casing 30 is formed with an oil flow path 37 that communicates with the first recess 33 and the second recess 34 and supplies lubricating oil to the bearings 17 and 28. There is. This is the only oil flow path shown in FIG. 1, but in reality, an oil supply path is formed so that lubricating oil can be supplied to all the bearings 16 to 18, 26 to 28.

To insert the rotor shaft 14b of the first male rotor 14 and the rotor shaft 15b of the first female rotor 15 into the bearing casing 50 provided on the low pressure side (right side in the drawing) of the first rotor set 13. The two through holes 51 and 52 are provided. Bearing covers 53 and 54 are attached to the tips of the through holes 51 and 52 extending from the first compression chamber 12, respectively. The bearing covers 53 and 54 and the bearing casing 50 form a bearing chamber 55 for accommodating the bearings 16 and 18. The bearing cover 53 is formed with a through hole 56 for inserting the rotor shaft 14b of the first drive side rotor (first male rotor 14 in this embodiment).

A motor casing 60 is provided at a position adjacent to the bearing casing 50. A gear chamber 62 for accommodating the gear assembly 61 is formed by the motor casing 60, the bearing casing 50, and the bearing covers 53 and 54.

The two rotor shafts 14b and 15b extend from the first compression chamber 12 to the bearing chamber 55 through the through holes 51 and 52 of the bearing casing 50, respectively. Further, the rotor shaft 14b on the drive side extends to the gear chamber 62 through the through hole 56 of the bearing cover 53. Further, a motor 63 is arranged adjacent to the gear chamber 62, and a motor shaft 64 extends from the motor 63 into the gear chamber 62. The motor shaft 64 and the rotor shaft 14b are mechanically connected via the gear assembly 61, and the rotational power of the motor 63 is transmitted to the first male rotor 14 which is the first drive side rotor via the gear assembly 61. It is supposed to be done.

In order to insert the rotor shaft 24a of the second male rotor 24 and the rotor shaft 25a of the second female rotor 25 into the bearing casing 70 provided on the high pressure side (left side in the drawing) of the second rotor set 23. The two through holes 71 and 72 are provided, respectively. Bearing chambers for accommodating bearings 26 and 27 by bearing covers 73 and 74 and bearing casing 70 to which bearing covers 73 and 74 are attached to the tips of through holes 71 and 72 extending from the second compression chamber 22. 75 is formed. The bearing chamber 75 also houses a balance piston 76 attached to the rotor shaft 24a.

FIG. 5 is a vertical sectional view of the compressor 1. The connection hole 14c and the rotor shaft (connection shaft) 24b are connected by a fixing screw 45. The second male rotor 24 is provided with an insertion hole 24c for inserting the fixing screw 45. The insertion hole 24c is provided so as to penetrate the central portion of the second male rotor 24 in the longitudinal direction. Further, the first male rotor 14 is provided with a screw fastening portion 14d adjacent to the insertion hole 24c for fastening the fixing screw 45. The fixing screw 45 is inserted from the end of the rotor shaft 24a through the insertion hole 24c, extends to the screw fastening portion 14d of the connection hole 14c, and is screwed at the screw fastening portion 14d. Specifically, as a mode of this screw fastening, the tip of the fixing screw 45 is a male screw, and the screw fastening portion 14d is a female screw.

The gas flow from intake to discharge in the compressor 1 of the present embodiment will be described. The rotor casing 30 is provided with an intake port 38 communicating with the first compression chamber 12, and gas is taken into the first compression chamber 12 from the intake port 38 (see arrow A). The gas compressed by the first rotor set 13 in the first compression chamber 12 is led out from the outlet 39a below the first rotor set 13 (see arrow B). The outlet 39a from the first compression chamber 12 communicates with the introduction port 39b of the second compression chamber 22. Therefore, the first compression chamber 12 and the second compression chamber 22 are fluidly communicated with each other. Therefore, the gas compressed in the first compression chamber 12 is supplied to the second compression chamber 22 (see arrow C). The gas supplied from the introduction port 39b to the second compression chamber 22 is compressed by the second rotor set 23 and discharged to the outside of the compressor from the discharge port 77 opened on the downstream side of the second compression chamber 22 (arrow). See D). As described above, in the compressor 1 of the present embodiment, the second compression chamber 22 is provided as a subsequent stage of the first compression chamber 12.

When the above discharge is performed, a pressing force is generated on the first rotor set 13 and the second rotor set 23 according to the compression action in the first compression chamber 12 and the second compression chamber 22. In the present embodiment, the first rotor set 13 and the second rotor set 23 are provided so that the pressing force presses the first male rotor 14 and the second male rotor 24 in the same axial direction. .. In other words, in the present embodiment, as shown in FIG. 5, the arrows P1 and P2 indicating the pressing force are aligned in the coaxial direction (to the right in the figure). Here, the pressing force generated by the compression action in these compression chambers is reduced by the balance piston 76 as described above.

According to this embodiment, the structure of the rotor casing 30 is simplified by devising the structure of the intermediate wall 31. Specifically, since the intermediate wall 31 is provided with the through hole 32, the connection shaft 24b connecting the first male rotor 14 and the second male rotor 24 can be guided through the through hole 32, and the first male rotor 24 can be guided. The connection between the rotor 14 and the second male rotor 24 can be easily secured. Further, since the first intermediate wall 31 is provided with the first recess 33, the first intermediate bearing 17 can be installed from the first opening 35 side like the first female rotor 15, and the second recess is formed in the intermediate wall 31. Since 34 is provided, the second intermediate bearing 28 can be installed from the second opening 36 side in the same manner as the second female rotor. In other words, the first intermediate bearing 17 and the first female rotor 15 can be installed from the same one side with respect to the intermediate wall 31, and similarly, the second intermediate bearing 28 and the second female rotor 25 can be installed on the intermediate wall 31. Can be installed from the same other side. Therefore, the necessary parts can be easily installed in the rotor casing 30, and the structure of the rotor casing 30 can be simplified. Further, in the above configuration, the first male rotor 14 (first drive side rotor) and the second male rotor 24 (second drive side rotor) are connected by the connecting portion 40 without providing a coupling. The rotor 14 and the second male rotor 24 are connected. As a result, it is not necessary to provide an intermediate chamber for installing the coupling, so that the structure of the rotor casing 30 can be simplified.

Further, according to the present embodiment, in both the first rotor set 13 and the second rotor set 23, the male screw rotor is driven to transmit the power to the female screw rotor. Comparing the case where power is transmitted from the male screw rotor to the female screw rotor and the case where power is transmitted from the female screw rotor to the male screw rotor, the transmission torque is smaller in the former case. .. Specifically, the number of teeth on the male screw rotor is generally less than the number of teeth on the female screw rotor. Therefore, when the male screw rotor makes one rotation, the female screw rotor rotates less than one rotation. That is, when power is transmitted from the male screw rotor to the female screw rotor, the transmission torque can be reduced as described above because the gear ratio is less than 1. Therefore, since the required power can be reduced, the load applied to the first rotor set 13 and the second rotor set 23 is reduced, and the tooth surface strength required for the first rotor set 13 and the second rotor set 23 is also reduced. In other words, the durability of the first rotor set 13 and the second rotor set 23 can be improved as compared with the case where power is transmitted from the female screw rotor to the male screw rotor.

Further, according to the present embodiment, since the relative positions of the first male rotor 14 and the second male rotor 24 in the axial direction are fixed by the fixing screw 45, the thrust forces generated in both rotors 14 and 24 are common. It becomes. Therefore, since the thrust bearing 26 that supports this common thrust force can be shared, the structure can be simplified. In the present embodiment, the first male rotor 14 is provided with the screwed portion 14d, and the second male rotor 24 is provided with the insertion hole 24c, but the second male rotor 24 is provided with the screwed portion 14d. Is provided, and the insertion hole 24c may be provided in the first male rotor 14.

Further, according to the present embodiment, by providing the balance piston 76 on the rotor shaft 24a of the second drive side rotor, a thrust force (pushing force) acting in common on the first male rotor 14 and the second male rotor 24 is applied. A force that opposes the pressure) can be applied to the rotor shaft 24a. Therefore, the thrust force applied to the thrust bearing 26 attached to the rotor shaft 24a can be reduced, so that the thrust bearing 26 can be miniaturized.

Further, according to the present embodiment, the insertion hole 24c can be easily formed. In the present embodiment, the second rotor set 23 in the rear stage is smaller and shorter in length than the first rotor set 13 in the previous stage. Therefore, from the viewpoint of the amount of processing for forming the insertion hole 24c, the amount of processing of the second drive side rotor 24 of the rear stage is smaller than that of the first drive side rotor 14 of the front stage, so that the insertion hole 24c can be easily processed. Can be formed.

Further, according to the present embodiment, the seal regions S1 and S2 form a shaft seal with respect to the through hole 32. Therefore, it is possible to prevent the fluid from leaking from the through hole 32 between the first compression chamber 12 and the second compression chamber 22, so that the performance of the compressor 1 can be improved.

Further, according to the present embodiment, the seal regions S11 and S21 form shaft seals for the first recess 33 and the second recess 34, respectively. Therefore, the leakage of the fluid from the first compression chamber 12 to the first recess 33 and the leakage of the fluid from the second compression chamber 22 to the second recess 34 can be prevented, so that the performance of the compressor 1 can be improved.

Further, according to the present embodiment, since the rotor casing 30 is formed of an integral casting without the rotor casing 30 being provided with a dividing surface, the man-hours for processing and assembling the rotor casing 30 can be reduced. Further, since the first rotor set 13 and the second rotor set 23 can be inserted through the openings 35 and 36 at both ends of the rotor casing 30, the first rotor set 13 and the second rotor set 23 can be easily inserted into the rotor casing 30. Can be placed in.

Further, according to the present embodiment, the diameter R1 of the tooth bottom of the first male rotor 14 and the diameter R2 of the tooth bottom of the second male rotor 24 can be brought close to each other. In the case of a structure in which the connecting shaft 24b is passed through the through hole 32 as described above, the through hole is formed by bringing the diameter R1 of the tooth bottom of the first male rotor 14 and the diameter R2 of the tooth bottom of the second male rotor 24 close to each other. The diameters at both ends of 32 can be made to be about the same (the same R0 in this embodiment). Therefore, the through hole 32 can be easily formed. In particular, when the first rotor set 13 has a so-called 4-6 tooth profile and the second rotor set 23 has a so-called 5-6 tooth profile, the diameter R1 of the tooth bottom of the first male rotor 14 and the tooth bottom of the second male rotor 24 The diameter of R2 can be substantially the same as that of R2.

Further, as a modification of the above embodiment, instead of mechanically connecting the first male rotor 14 and the second male rotor 24, the first female rotor 15 and the second female rotor 25 are mechanically connected. You may connect to.

According to this modification, in both the first rotor set 13 and the second rotor set 23, power is transmitted from the female screw rotor to the male screw rotor. From the viewpoint of the gear ratio, when power is transmitted from the female screw rotor to the male screw rotor, the gear ratio is 1 or more. Therefore, since the rotation speeds of the first rotor set 13 and the second rotor set 23 can be increased, the discharge air volume at the same rotation speed can be increased as compared with the case of driving the male rotor.

Although specific embodiments of the present invention and variations thereof have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention. For example, an embodiment of the present invention may be obtained by appropriately combining the contents of the individual embodiments.

1 Compressor (oil-cooled two-stage screw compressor)
10 Low-stage compression unit 12 1st compression chamber 13 1st rotor set 14 1st male rotor (1st drive side rotor)
14a, 14b Rotor shaft 14c Connection hole 14d Screw fastening part 15 First female rotor (first driven side rotor)
15a, 15b Rotor shaft 16,18 bearing 17 bearing (first intermediate bearing)
20 High-stage compression unit 22 Second compression chamber 23 Second rotor set 24 Second male rotor (second drive side rotor)
24a Rotor shaft 24b Rotor shaft (connection shaft)
24c Insertion hole 25 2nd female rotor (2nd driven side rotor)
25a, 25b Rotor shaft 26 bearing (thrust bearing)
27 Bearing 28 Bearing (2nd intermediate bearing)
30 Rotor casing 31 Intermediate wall 32 Through hole 33 First recess 34 Second recess 35 First opening 36 Second opening 37 Oil flow path 38 Intake port 39a Outlet port 39b Introduction port 40 Connection part 41 Anti-rotation structure 42, 43 Key groove 44 Key member 45 Fixing screw 50 Bearing casing 51,52 Through hole 53,54 Bearing cover 55 Bearing chamber 56 Through hole 60 Motor casing 61 Gear assembly 62 Gear chamber 63 Motor 64 Motor shaft 70 Bearing casing 71,72 Through hole 73 , 74 Bearing cover 75 Bearing chamber 76 Balanced piston 77 Discharge port

Claims (10)

A first rotor set having a first drive-side rotor and the first driven side rotor is screw rotors,
A second rotor set having a second drive-side rotor and the second driven side rotor is screw rotors,
A connection portion that mechanically connects the first drive side rotor and the second drive side rotor,
A rotor casing that includes a first compression chamber that houses the first rotor set and a rotor casing that fluidly communicates with the first compression chamber to form a second compression chamber that houses the second rotor set.
The rotor casing has an intermediate wall that separates the first compression chamber and the second compression chamber.
The connection portion includes a connection shaft formed on either one of the first drive side rotor or the second drive side rotor, a connection hole formed on the other side and fitting the connection shaft coaxially, and the connection shaft. And has an anti-rotation structure that prevents the relative rotation of the connection hole.
The intermediate wall includes a through hole for inserting the connecting shaft, a first recess for installing a first intermediate bearing that pivotally supports the first driven side rotor from the first compression chamber side, and the above. the second intermediate bearing for supporting the second driven side rotor have a second recess for installation from the second compression chamber side,
One of the first drive side rotor and the second drive side rotor is inserted to insert a fixing screw for fixing the axial relative position between the first drive side rotor and the second drive side rotor. has a hole and the other have a screw portion for fastening the fixing screws adjacent to the insertion hole, oil-cooled two-stage screw compressor. The first drive side rotor is a male screw rotor.
The oil-cooled two-stage screw compressor according to claim 1, wherein the second drive-side rotor is also a male screw rotor. The first drive side rotor is a female screw rotor.
The oil-cooled two-stage screw compressor according to claim 1, wherein the second drive-side rotor is also a female screw rotor. The first rotor set and the second rotor set so that the compression action in the first compression chamber and the second compression chamber produces a pressing force that presses the first rotor set and the second rotor set in the same axial direction. A second rotor set is provided,
A thrust bearing capable of supporting at least a thrust load and a force resisting the pressing force are applied to the second drive side rotor at an end opposite to the connection portion with respect to the second drive side rotor. further comprising a balance piston for an oil-cooled two-stage screw compressor according to claim 1. The second compression chamber is arranged after the first compression chamber.
The insertion hole is provided in the second drive side rotor.
The oil-cooled two-stage screw compressor according to any one of claims 1 to 4, wherein the screwing portion is provided on the first drive side rotor. A part of the end of the first drive side rotor has entered the one end of the through hole, and a part of the end of the second drive side rotor has entered the other end of the through hole. The oil-cooled two-stage screw compressor according to any one of claims 1 to 5. Diameter of the through hole is smaller than the diameter of the tooth bottom of the first drive-side rotor, and, by not smaller than the diameter of the tooth bottom of the second drive-side rotor, and the edge portion of the through hole, the second The oil-cooled two-stage type according to any one of claims 1 to 6, wherein a seal region is formed between the tooth bottom of the 1-drive side rotor and the tooth bottom of the 2nd drive-side rotor. Screw compressor. The diameter of the first recess is smaller than the diameter of the tooth bottom of the first driven rotor, and a part of the end portion of the first driven rotor has entered the first recess. A seal region is formed between the edge of the first recess and the tooth bottom of the first driven rotor.
The diameter of the second recess is smaller than the diameter of the tooth bottom of the second driven rotor, and a part of the end portion of the second driven rotor has entered the second recess. The oil-cooled type according to any one of claims 1 to 7, wherein a seal region is formed between the edge of the second recess and the tooth bottom of the second driven rotor. Two-stage screw compressor. The rotor casing is made of an integral casting, and has a first opening into which the first rotor set can be inserted from the outside of the first compression chamber into the inside of the first compression chamber toward the intermediate wall. According to claim 1, each of both ends has a second opening into which the second rotor set can be inserted from the outside of the second compression chamber to the inside of the second compression chamber toward the intermediate wall. The oil-cooled two-stage screw compressor according to any one of claims 8. The male screw rotor of the first rotor set has a four-toothed shape, and the female screw rotor of the first rotor set has a six-toothed shape.
The male screw rotor of the second rotor set has a five-toothed shape, and the female screw rotor of the second rotor set has a six-toothed shape, according to any one of claims 1 to 9. Oil-cooled two-stage screw compressor.

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