Screw Compressor

Abstract

To provide a screw compressor of high reliability and high efficiency.SOLUTION: A screw compressor for compressing a working medium is provided with: first and second screw rotors sucking the working medium and compressing and discharging the working medium; a first bearing rotatably supporting one end side of the first screw motor connected to a rotating shaft of a power source at one end side; a casing housing the first screw rotor and the first bearing; a shaft seal member disposed at a side opposite to a tooth-shaped portion of the first screw rotor with respect to the first bearing on the inside of the casing and sealing a through hole of the casing to which a shaft portion of the first screw rotor connected to an output shaft of the power source is inserted; a partition for partitioning the first bearing and the shaft seal member from each other in the casing; and a liquid supply passage disposed on the casing, and having a first liquid supply port for supplying a lubricant liquid to the first bearing and a second liquid supply port for supplying the lubricant liquid to the shaft seal member.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a screw compressor, and is suitable for use in a screw compressor equipped with a liquid supply mechanism. [Background technology]

[0002] As a conventional screw compressor, an oil-cooled screw compressor is disclosed in Patent Document 1. This screw compressor has an oil supply hole through which lubricating oil is supplied to a space housing a suction bearing and a mechanical seal, a first recovery hole is formed in a partition wall between the screw rotor and the suction side bearing, and a second recovery hole is formed bypassing the first recovery hole, and these first and second recovery holes also have a structure that opens into a compressed air suction passage.

[0003] With this structure, in the screw compressor disclosed in Patent Document 1, a portion of the lubricating oil is recovered via the second recovery hole, and the amount of lubricating oil passing through the suction side bearing is kept to the minimum necessary for lubrication, making it possible to reduce the stirring loss of the suction side bearing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-21758 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the screw compressor disclosed in Patent Document 1, the bearings are lubricated through a process in which a portion of the lubricating oil accumulated in the space in which the suction side bearing and the mechanical seal are housed passes through the suction side bearing and is recovered in the first recovery hole.

[0006] For this reason, in principle, the suction side bearing is designed to agitate the lubricating oil that has accumulated in the space and also agitate the lubricating oil that passes through the suction side bearing. This means that there is a large agitation loss, especially when agitating the lubricating oil that has accumulated in the space, which is a factor in reducing the performance of the compressor.

[0007] The present invention has been made in consideration of the above points, and aims to propose a highly reliable and efficient screw compressor which can effectively prevent a decrease in performance as a compressor. [Means for solving the problem]

[0008] In order to solve the above problem, the present invention provides a screw compressor for compressing a working medium, the screw compressor comprising: first and second screw rotors for sucking in, compressing and discharging the working medium; a first bearing for rotatably supporting one end of the first screw rotor, the one end of which is connected to a rotating shaft of a power source; a casing in which the first screw rotor and the first bearing are housed; and a second bearing for supporting the first screw rotor and the first bearing, the first bearing being disposed inside the casing on the opposite side of a toothed portion of the first screw rotor with respect to the first bearing, the second bearing being disposed inside the casing on the opposite side of the toothed portion of the first screw rotor and ... rotate The casing is provided with a shaft seal member that seals the through hole of the casing through which the shaft portion of the first screw rotor connected to a shaft passes, a partition wall that isolates the first bearing and the shaft seal member inside the casing, and a liquid supply path provided in the casing having a first liquid supply port for supplying lubricating liquid to the first bearing and a second liquid supply port for supplying the lubricating liquid to the shaft seal member.

[0009] As a result, appropriate amounts of lubricating liquid can be supplied independently to the shaft seal member and the first bearing, thereby suppressing loss of lubricating liquid in the first bearing due to excessive supply of lubricating liquid to the first bearing. Effect of the Invention

[0010] According to the present invention, a highly reliable and highly efficient screw compressor can be realized. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a horizontal sectional view showing the configuration of a male rotor side in the screw compressor according to the first embodiment. [Diagram 2] FIG. 2 is a vertical sectional view showing the configuration of a male rotor side in the screw compressor according to the first embodiment. [Diagram 3] FIG. 2 is a vertical sectional view showing the configuration of a liquid supply path on the male rotor side in the screw compressor according to the first embodiment. [Figure 4] FIG. 2 is a vertical sectional view showing the configuration of a female rotor side in the screw compressor according to the first embodiment. [Diagram 5] FIG. 2 is a conceptual diagram illustrating an external path of a lubricating liquid injected into the screw compressor according to the first embodiment. [Figure 6] FIG. 11 is a vertical sectional view showing the configuration of a male rotor side of a screw compressor according to a second embodiment. [Figure 7] FIG. 11 is a vertical sectional view showing the configuration of a male rotor side of a screw compressor according to a third embodiment. [Figure 8] FIG. 10 is a vertical sectional view showing the configuration of a male rotor side of a screw compressor according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will now be described in detail with reference to the drawings.

[0013] (1) First embodiment Fig. 1 and Fig. 2 show a screw compressor 1 according to a first embodiment. Fig. 1 is a view (horizontal cross-sectional view) taken along line CC in Fig. 2, and Fig. 2 is a view (vertical cross-sectional view) taken along line AA in Fig. 1.

[0014] As shown in FIGS. 1 and 2, a screw compressor 1 of the present embodiment is configured to include a pair of screw rotors, that is, a male rotor 2 and a female rotor 3, and a casing 4 that houses the male rotor 2 and the female rotor 3 therein.

[0015] The male rotor 2 is composed of a toothed portion 2A having a plurality of teeth (lobes) extending helically, a suction-side shaft portion 2B formed at one end side of the toothed portion 2A in the rotor axial direction (the left side in Figs. 1 and 2, the same applies below), and a discharge-side shaft portion 2C formed at the other end side of the toothed portion 2A in the rotor axial direction (the right side in Figs. 1 and 2, the same applies below). The suction-side shaft portion 2B of the male rotor 2 is rotatably supported by a suction-side bearing 5 (hereinafter referred to as the first suction-side bearing), and the discharge-side shaft portion 2C of the male rotor 2 is rotatably supported by a discharge-side bearing 6 (hereinafter referred to as the first discharge-side bearing).

[0016] Similarly, the female rotor 3 is comprised of a toothed section 3A having a plurality of teeth formed thereon to mesh with the teeth of the male rotor 2, a suction-side shaft section 3B formed at one end in the rotor axial direction of the toothed section 3A, and a discharge-side shaft section 3C formed at the other end in the rotor axial direction of the toothed section 3A. The suction-side shaft section 3B of the female rotor 3 is rotatably supported by a suction-side bearing (hereinafter referred to as the second suction-side bearing) 7, and the discharge-side shaft section 3C of the female rotor 3 is rotatably supported by a discharge-side bearing (hereinafter referred to as the second discharge-side bearing) 8.

[0017] The suction side shaft 2B of the male rotor 2 passes through the casing 4 and is connected to the rotating shaft of a motor (not shown). This allows the male rotor 2 to be rotated integrally with the rotating shaft of the motor by driving the motor, and accordingly the female rotor 3 can also be rotated integrally with the male rotor 2.

[0018] The casing 4 is composed of a main casing 4A, a discharge side casing 4B connected to the other end side of the main casing 4A in the rotor axial direction, and a suction side casing 4D connected to one end side of the main casing 4A in the rotor axial direction via a suction side partition 4C.

[0019] The discharge-side casing 4B is provided with a first discharge-side bearing accommodating space 9A and a second discharge-side bearing accommodating space 9B which are provided independently of each other, with the first discharge-side bearing 6 accommodated in the first discharge-side bearing accommodating space 9A and the second discharge-side bearing 8 accommodated in the second discharge-side bearing accommodating space 9B. The discharge-side casing 4B is also formed with a discharge port 10 located radially outward (lower in FIG. 2) of the toothed portions 2A, 3A of the male rotor 2 and the female rotor 3, and a discharge path 11 connecting the discharge port 10 and a bore 12 which will be described later.

[0020] The main casing 4A is formed with a bore 12 for accommodating the toothed portion 2A of the male rotor 2 and the toothed portion 3A of the female rotor 3. The bore 12 is a space having a shape of two cylindrical holes partially overlapping each other for accommodating the toothed portion 2A of the male rotor 2 and the toothed portion 3A of the female rotor 3 with their teeth meshing.

[0021] A working chamber is formed by the inner wall surface of the bore 12, the tooth grooves of the male rotor 2, and the tooth grooves of the female rotor 3. The working chamber is formed so that its volume gradually decreases from one end to the other end in the rotor axial direction. As a result, a working medium such as air sucked in from the suction port 13 is gradually compressed in the working chamber and discharged from the discharge port 10 via the discharge path 11.

[0022] The suction port 13 is formed on the outer side in the rotor radial direction (upper side in FIG. 2) of the toothed portion 2A of the male rotor 2 and the toothed portion 3A of the female rotor 3 in the main casing 4A. The suction port 13 communicates with the working chamber via the suction space 14, and the working medium sucked from the suction port 13 is supplied to the working chamber via the suction space 14.

[0023] A cylindrical first suction side bearing accommodating space 15 and a cylindrical second suction side bearing accommodating space 16 are formed on an end face on one end side of the rotor axial direction of main casing 4A. The first suction side bearing 5 is fitted into first suction side bearing accommodating space 15, and the second suction side bearing 7 is fitted into second suction side bearing accommodating space 16.

[0024] The main casing 4A also has a first bearing communication space 17 which is slightly smaller in diameter than the first suction side bearing accommodating space 15 and which communicates between the first suction side bearing accommodating space 15 and the suction space 14, and a second bearing communication space 18 which is slightly smaller in diameter than the second suction side bearing accommodating space 16 and which communicates between the second suction side bearing accommodating space 16 and the suction space 14.

[0025] Furthermore, a suction side partition 4C is fixed to one end face of the main casing 4A in the rotor axial direction, and a suction side casing 4D is fixed to the end of the suction side partition 4C in the rotor axial direction. A shaft seal space 20 communicating with a through hole 19 through which the suction side shaft portion 2B of the male rotor 2 is inserted is formed in the suction side casing 4D on the surface facing the suction side partition 4C, and a shaft seal member 21 for sealing the through hole 19 is disposed in the shaft seal space 20.

[0026] In addition, the casing 4 of the screw compressor 1 is provided with a first working chamber liquid supply port 22 communicating with the working chamber in the bore 12, and liquid can be injected into the working chamber via this first working chamber liquid supply port 22. Also, a first suction side liquid supply port 23 is provided on the suction port 13 side of the casing 4, and a first discharge side liquid supply port 24 is provided on the discharge port 10 side of the casing 4, and liquid can be injected into the shaft seal space 20 and the first suction side bearing housing space 15 via the first suction side liquid supply port 23, and liquid can be injected into the first discharge side bearing housing space 9A via the first discharge side liquid supply port 24.

[0027] The purpose of injecting liquid into the working chamber, the shaft seal space 20, the first suction side bearing accommodation space 15, and the first discharge side bearing accommodation space 9A is to cool the mechanical components and the compressed air, to lubricate the first suction side bearing 5 and the first discharge side bearing 6, and to improve the sealing performance of the shaft seal member 21. The liquid injected at this time is oil or water. Hereinafter, this liquid will be referred to as the lubricating liquid.

[0028] The lubricating liquid injected into the first suction side liquid supply port 23 passes through the inside of the casing 4 and is released into the shaft seal space 20 via the first liquid supply port 25, and is also released into the first suction side bearing accommodating space 15 via the second liquid supply port 26.

[0029] 3 shows the flow path of the lubricating liquid inside the casing 4, which is supplied to the first suction side bearing 5 and the shaft seal member 21. The arrows in the figure indicate the supply direction of the lubricating liquid. As shown in FIG. 3, a first liquid supply path 27 is provided inside the casing 4, which connects the first suction side liquid supply port 23 to the first and second liquid supply ports 25, 26. The first liquid supply path 27 is branched into first and second branch paths 27A, 27B midway, with the first branch path 27A communicating with the first liquid supply port 25 and the second branch path 27B communicating with the second liquid supply port 26.

[0030] In this case, the first liquid supply port 25 opens toward the shaft seal member 21 arranged in the shaft seal space 20, so that the lubricating liquid that has been injected into the casing 4 from the first suction-side liquid supply port 23 and flowed into the first branch passage 27A is discharged from the first liquid supply port 25 and supplied to the shaft seal member 21. The shaft seal space 20 also communicates with the suction space 14 via a bypass communication passage 28, so that the lubricating liquid injected into the shaft seal space 20 is discharged into the suction space 14 via the bypass communication passage 28.

[0031] On the other hand, the second liquid supply port 26 opens toward the first suction side bearing 5 accommodated in the first suction side bearing accommodating space 15, so that the lubricating liquid injected into the casing 4 from the first suction side liquid supply port 23 and flowing into the second branch path 27B is released from the second liquid supply port 26 and supplied to the first suction side bearing 5 from the male rotor 2 side.

[0032] In this case, since the first suction side bearing 5 is partially exposed to the suction space 14 via the first bearing communication space 17 of the main casing 4A, the lubricating liquid supplied to the first suction side bearing 5 from the second liquid supply port 26 flows out into the suction space 14 via the first bearing communication space 17. This lubricating liquid then merges with the lubricating liquid that has flowed into the suction space 14 via the bypass communication passage 28, and is transported to the working chamber together with the working medium that has flowed into the suction space 14 from the suction port 13.

[0033] Here, let us consider the agitation loss of the lubricating liquid in the first suction side bearing 5. In this embodiment, the first suction side bearing 5 is assumed to be a roller bearing, but the present invention is not limited to this, and the first suction side bearing 5 may be another rolling bearing such as a ball bearing.

[0034] Generally, when a rolling bearing rotates in a lubricating liquid, the rolling elements in the rolling bearing experience fluid resistance as they roll while pushing aside the lubricating liquid. In addition, in this embodiment, the structure is such that the lubricating liquid supplied to the first suction side bearing 5 is constantly replaced, so the rolling elements must work to accelerate the newly introduced lubricating liquid. The combination of these factors constitutes the churning loss.

[0035] In this embodiment, as is clear from Fig. 3, the location where the first suction side bearing 5 is arranged is higher than the lowest end of the suction space 14, making it difficult for lubricating liquid to accumulate. Furthermore, when the screw compressor 1 is installed with the male rotor 2 and female rotor 3 horizontal as shown in Fig. 3, the first bearing communicating space 17 is formed so that its lowest end is lower than the height position of the lowest end of the inner diameter of the outer ring of the first suction side bearing 5, making it easy to discharge the lubricating liquid in the rolling element raceway of the first suction side bearing 5 into the suction space 14.

[0036] Furthermore, for example, if the second liquid supply port 26 is formed on the suction side partition wall 4C side, the lubricating liquid supplied to the first suction side bearing 5 through the second liquid supply port 26 must pass through the rolling element raceway of the rotating first suction side bearing 5 in order to flow out to the suction space 14 side, resulting in a large agitation loss. In contrast, in this embodiment, the second liquid supply port 26 is formed so that the lubricating liquid can be supplied to the first suction side bearing 5 from the male rotor 2 side, so that all of the lubricating liquid supplied to the first suction side bearing 5 does not need to pass through the rolling element raceway of the rotating first suction side bearing 5. Therefore, it can be said that the screw compressor 1 has a structure in which the agitation loss of the lubricating liquid in the rolling element raceway of the first suction side bearing 5 is small.

[0037] Next, a description will be given of the amount of lubricating liquid supplied to the shaft seal member 21 and the first suction side bearing 5. As described in the above-mentioned Patent Document 1, the amount of lubricating liquid required for the first suction side bearing 5 is generally less than the amount required for the shaft seal member 21, such as a mechanical seal.

[0038] In this regard, in the screw compressor 1 of this embodiment, the first suction side bearing accommodating space 15 in which the first suction side bearing 5 is accommodated and the shaft seal space 20 in which the shaft seal member 21 is arranged are separated by the suction side partition 4C, and a first liquid supply port 25 for supplying lubricating liquid to the shaft seal member 21 and a second liquid supply port 26 for supplying lubricating liquid to the first suction side bearing 5 are provided independently, so that an appropriate amount of lubricating liquid can be supplied to the shaft seal member 21 and the first suction side bearing 5, respectively.

[0039] The distribution of the amount of lubricating liquid supplied to the shaft seal member 21 and the first suction side bearing 5 can be determined by the pressure loss of the first liquid supply path 27, specifically, by the length and hydraulic diameter of the first and second branch paths 27A, 27B, and the diameters of the first and second liquid supply ports 25, 26. In this embodiment, since the amount of lubricating liquid required for the shaft seal member 21 is greater than the amount of lubricating liquid required for the first suction side bearing 5 as described above, the length and hydraulic diameter of the first and second branch paths 27A, 27B, and the diameters of the first and second liquid supply ports 25, 26 are selected so that the pressure loss from the first suction side liquid supply port 23 to the first liquid supply port 25 is smaller than the pressure loss from the first suction side liquid supply port 23 to the second liquid supply port 26.

[0040] Fig. 4 is a view (vertical cross-sectional view) taken along the line BB in Fig. 1. The main casing 4A is provided with a second working chamber liquid supply port 30 communicating with the working chamber in the bore 12, and lubricating liquid can be supplied to the working chamber from outside the screw compressor 1 via the second working chamber liquid supply port 30.

[0041] In addition, a second discharge side liquid supply port 31 is formed in the discharge side casing 4B, and lubricating liquid can be supplied to the second discharge side bearing 8 arranged in the second discharge side bearing accommodating space 9B through this second discharge side liquid supply port 31.

[0042] Further, a second suction side liquid supply port 32 is formed on the outer side of the rotor radial direction in the suction side casing 4D, and a third liquid supply port 33 is provided in the main casing 4A toward the second suction side bearing 7 accommodated in the second suction side bearing accommodating space 16, and the third liquid supply port 33 is communicated with the second suction side liquid supply port 32 via a second liquid supply path 34 formed inside the casing 4. As a result, by injecting lubricating liquid into the screw compressor 1 via the second suction side liquid supply port 32, the lubricating liquid can be supplied from the third liquid supply port 33 via the second liquid supply path 34 to the second suction side bearing 7.

[0043] In this case, since the second suction side bearing 7 is partially exposed to the suction space 14 through the second bearing communication space 18 of the main casing 4A, the lubricating liquid supplied to the second suction side bearing 7 from the second suction side liquid supply port 32 through the second liquid supply path 34 flows out into the suction space 14 through the second bearing communication space 18, and then is transported to the working chamber together with the working medium that has flowed into the suction space 14 from the suction port 13.

[0044] By configuring the second fluid supply path 34 in this manner, the agitation loss of the lubricating fluid in the second suction side bearing 7 can be kept small due to a mechanism similar to that of the agitation loss of the lubricating fluid in the first suction side bearing 5.

[0045] The second working chamber liquid supply port 30, the second suction side liquid supply port 32 and the second discharge side liquid supply port 31 may be formed separately from the corresponding ones among the first working chamber liquid supply port 22, the first suction side liquid supply port 23 and the first discharge side liquid supply port 24 described above in Figure 2, or they may be provided in the same location, i.e., the first and second working chamber liquid supply ports 22, 30, the first and second suction side liquid supply ports 23, 32 and the first and second discharge side liquid supply ports 24, 31 may each be the same.

[0046] Fig. 5 shows an external path of the lubricating liquid injected into the screw compressor 1 of this embodiment. The lubricating liquid injected into the screw compressor 1 is discharged from the discharge port 10 (Figs. 2 and 4) in a state where it is mixed with the working medium compressed by the screw compressor 1. Then, this lubricating liquid is separated from the working medium compressed by the oil separator 40, cooled by a cooler 41, and then provided to the first and second working chamber liquid supply ports 22, 30 (Figs. 2 and 4) via an oil filter (and a check valve) 42, and is injected into the working chambers via these first and second working chamber liquid supply ports 22, 30, respectively.

[0047] The lubricating liquid is also branched after passing through the oil filter 42 and is provided to the first and second suction side liquid supply ports 23, 32 (FIGS. 2 and 4) and the first and second discharge side liquid supply ports 24, 31 (FIGS. 2 and 4), and is also supplied to the shaft seal member 21 (FIG. 2) in the shaft seal space 20 (FIG. 2) via the first suction side liquid supply port 23, the first suction side bearing 5 in the first suction side bearing housing space 15 (FIG. 2), the second suction side bearing 7 in the second suction side bearing housing space 15, the first discharge side bearing 6 (FIG. 1) housed in the first discharge side bearing housing space 9A (FIG. 1), and the second discharge side bearing 8 (FIG. 1) housed in the second discharge side bearing housing space 9B (FIG. 1). The branching of the lubricating liquid is not limited to the outside of the screw compressor 1 as shown in FIG. 5, but may be branched inside the casing 4 of the screw compressor 1.

[0048] As described above, in the screw compressor 1 of this embodiment, the first suction side bearing accommodation space 15 in which the first suction side bearing 5 is accommodated and the shaft seal space 20 in which the shaft seal member 21 is disposed are separated by the suction side partition wall 4C, and the first liquid supply port 25 for supplying lubricating liquid to the shaft seal member 21 and the second liquid supply port 26 for supplying lubricating liquid to the first suction side bearing 5 are provided independently, so that appropriate amounts of lubricating liquid can be independently supplied to the shaft seal member 21 and the first suction side bearing 5. Therefore, according to the screw compressor 1, it is possible to suppress agitation loss of the lubricating liquid in the first suction side bearing 5 caused by an excessive amount of lubricating liquid being supplied to the first suction side bearing 5, and therefore a highly reliable and efficient screw compressor can be realized.

[0049] Furthermore, in the present screw compressor 1, the second liquid supply port 26 is formed so that lubricating liquid can be supplied from the male rotor 2 side to the first suction side bearing 5, and therefore all of the lubricating liquid supplied to the first suction side bearing 5 does not need to pass through the rolling element raceway of the rotating first suction side bearing 5. Therefore, according to the present screw compressor 1, the agitation loss of the lubricating liquid in the first suction side bearing 5 is small, and a more efficient screw compressor can be realized.

[0050] (2) Second embodiment 6, in which the same reference numerals are assigned to parts corresponding to those in FIG. 2, shows a vertical cross section of a screw compressor 50 according to a second embodiment. This screw compressor 50 differs from the screw compressor 1 of the first embodiment in that a bypass communication passage 52 is configured in a casing 51 (suction side casing 50D, suction side partition wall 50C, and main casing 50A) so as to communicate between the shaft seal space 20 and the bore 12.

[0051] For this reason, in the screw compressor 50, the main casing 50A does not have a first working chamber liquid supply port 22 (Figure 2) and a path connecting the first working chamber liquid supply port 22 and the bore 12, and the lubricating liquid supplied to the shaft seal member 21 in the shaft seal space 20 is discharged into the bore 12 via the bypass connecting passage 52.

[0052] According to the screw compressor 50 of the present embodiment having the above-mentioned configuration, similarly to the screw compressor 1 of the first embodiment, it is possible to suppress the churning loss in the first and second suction side bearings 5, 7 to be low while supplying a necessary and sufficient amount of lubricating liquid to the first and second suction side bearings 5, 7 and the shaft seal member 21. Therefore, according to the present embodiment as well, it is possible to provide a screw compressor that is highly reliable and highly efficient.

[0053] (3) Third embodiment 7, in which parts corresponding to those in Fig. 2 are denoted by the same reference numerals, shows a vertical cross section of a screw compressor 60 according to a third embodiment. This screw compressor 60 has a similar configuration to the screw compressor 1 of the first embodiment, except that the position of the second liquid supply port 62 is different.

[0054] In practice, in the screw compressor 60 of this embodiment, a second liquid supply port 62 is provided in the suction side partition 60C so that lubricating liquid can be supplied to the first suction side bearing 5 from the suction side partition 60C side, and a second branch path 63B of the first liquid supply path 63 is provided in the suction side casing 60D and the suction side partition 60C so as to communicate between this first liquid supply port 62 and the first suction side liquid supply port 23.

[0055] As a result, in this screw compressor 60, the lubricating liquid supplied to the first suction side bearing 5 from the second liquid supply port 62 passes through the rolling element raceway of the rotating first suction side bearing 5, resulting in greater agitation loss in the first suction side bearing 5 than in the screw compressor 1 of the first embodiment.

[0056] However, in the screw compressor 60, since the first liquid supply port 62 is provided on the suction side partition 60C side of the first suction side bearing 5, there is no need to provide a portion in the main casing 4A for providing the first liquid supply port opposite the first suction side bearing 5. As a result, the opening area of ​​the first bearing communication space 17 can be made larger, so that the lubricating liquid is less likely to stagnate in the rolling element raceway of the first suction side bearing 5 and the stirring loss in the first suction side bearing 5 can be kept low.

[0057] According to the screw compressor 60 of the present embodiment having the above-mentioned configuration, similarly to the screw compressor 1 of the first embodiment, it is possible to keep the agitation loss in the first suction side bearing 5 low while supplying a necessary and sufficient amount of lubricating liquid to the first suction side bearing 5 and the shaft seal member 21. Therefore, according to the present embodiment as well, it is possible to provide a screw compressor that is highly reliable and highly efficient.

[0058] (4) Fourth embodiment Figure 8, in which parts corresponding to those in Figure 3 are designated by the same reference numerals, shows a vertical cross section of a portion of a screw compressor 70 according to a fourth embodiment. Screw compressor 70 is configured similarly to screw compressor 1 of the first embodiment, except that a through hole 72 for inserting suction side shaft portion 2B of male rotor 2, which is formed in suction side partition wall 71, is larger than that in screw compressor 1 of the first embodiment.

[0059] For this reason, in the screw compressor 70 of this embodiment, most of the lubricating liquid supplied to the first suction side bearing 5 via the second liquid supply port 26 flows out into the suction space 14, while a remaining portion passes through the first suction side bearing 5 and flows into the shaft seal space 20 through the through hole 72, and then merges with the lubricating liquid supplied to the shaft seal space 20 via the first liquid supply port 25 and is discharged into the suction space 14 via the bypass connecting passage 28.

[0060] As described above, in the screw compressor 70, a portion of the lubricating liquid supplied from the second liquid supply port 26 to the first suction side bearing 5 passes through the rolling element raceway of the rotating first suction side bearing 5. However, the lubricating liquid passing through the rolling element raceway of the first suction side bearing 5 quickly flows into the shaft seal space 20 via the through hole 72, so that the lubricating liquid is less likely to stagnate in the rolling element raceway of the first suction side bearing 5. As a result, the agitation loss in the first suction side bearing 5 can be kept lower than in the screw compressor 1 of the first embodiment.

[0061] According to the screw compressor 70 of the present embodiment having the above-mentioned configuration, it is possible to suppress the agitation loss in the first suction side bearing 5 to be lower than that in the screw compressor 1 of the first embodiment, while supplying a necessary and sufficient amount of lubricating liquid to the first suction side bearing 5 and the shaft seal member 21. Therefore, according to the present embodiment, it is possible to provide a screw compressor that is highly reliable and highly efficient.

[0062] (5) Other embodiments In the above-mentioned first to fourth embodiments, only the suction side shaft portion of the male rotor 2 is connected to the rotating shaft of a motor serving as a power source. However, the present invention is not limited to this, and the present invention can also be applied to a screw compressor in which the suction side bearing of the female rotor 3 is connected to the rotating shaft of the power source instead of or in addition to the male rotor 2.

[0063] In addition, in the above-mentioned first to fourth embodiments, a liquid supply path (first branch path) communicating with the first liquid supply port and a liquid supply path (second branch path) communicating with the second liquid supply port are configured to branch off inside the casing, but the present invention is not limited to this, and these liquid supply paths may originally be formed separately (liquid supply ports from the outside may be formed separately).

[0064] Furthermore, in the above-mentioned third embodiment, the second liquid supply port 62 is provided in the suction side partition 60C so that lubricating liquid can be supplied to the first suction side bearing 5 from the suction side partition 60C side. However, the present invention is not limited to this, and the third liquid supply port 26 described above with reference to Figure 6 may also be provided in the suction side partition 60C so that lubricating liquid can be supplied to the second suction side bearing 7 from the suction side partition 60C side. [Industrial Applicability]

[0065] The present invention can be widely applied to screw compressors of various configurations that compress a working medium. [Explanation of symbols]

[0066] 1,50,60,70...Screw compressor, 2...Male rotor, 2A,3A...Toothed portion, 2B,3B...Suction side shaft portion, 2C,3C...Discharge side shaft portion, 3...Female rotor, 4,51...Casing, 5,7...Suction side bearing, 6,8...Discharge side bearing, 9A,9B...Discharge side bearing accommodating space, 10...Discharge port, 12...Bore, 13...Suction port, 14...Suction space, 15,16... ...Suction side bearing accommodating space, 17, 18, 72...bearing communication space, 19...through hole, 20...shaft seal space, 21...shaft seal member, 22, 30...working chamber liquid supply port, 23, 32...suction side liquid supply port, 24, 31...discharge side liquid supply port, 25, 26, 33, 62...liquid supply port, 27, 34, 63...liquid supply path, 27A, 27B, 63A, 63B...branch path, 28, 52...bypass communication passage.

Claims

1. In a screw compressor for compressing a working medium, First and second screw rotors that suck in, compress, and discharge the working medium; a first bearing that rotatably supports one end of the first screw rotor, the one end of which is connected to a rotating shaft of a power source; a casing in which the first screw rotor and the first bearing are housed; a shaft seal member disposed on an opposite side of the toothed portion of the first screw rotor with respect to the first bearing inside the casing, and configured to seal a through hole of the casing through which a shaft portion of the first screw rotor connected to the rotating shaft of the power source is inserted; a partition wall separating the first bearing and the shaft seal member from each other within the casing; a liquid supply path provided in the casing, the liquid supply path having a first liquid supply port for supplying lubricating liquid to the first bearing and a second liquid supply port for supplying the lubricating liquid to the shaft seal member; A screw compressor comprising:

2. The shaft seal member is disposed in a first space provided in the casing, the first bearing is disposed in a second space provided in the casing, a toothed portion on which teeth are formed in the screw rotor, one end side of which is connected to the rotary shaft of the power source, is accommodated in a third space provided in the casing, the first and second spaces are separated by the partition wall, the first space is communicated with the third space via a bypass communication passage, The lubricating liquid supplied to the first space is discharged to the third space through the bypass communication passage.

2. The screw compressor according to claim 1 .

3. The first liquid supply port includes: A lubricating oil supply pipe is formed in the casing so as to supply the lubricating liquid to the first bearing from the screw rotor side.

2. The screw compressor according to claim 1 .

4. a communication space that communicates the second space and the third space, The lubricating liquid supplied to the first bearing is discharged to the third space through the communication space.

3. The screw compressor according to claim 2 .

5. The communication space is formed such that, when the first and second screw rotors are installed horizontally, the lowest end of the communication space is lower than the lower end position of the inner diameter of the outer ring of the first bearing.

5. The screw compressor according to claim 4.

6. a second bearing that rotatably supports one end of the second screw rotor, the one end of the second screw rotor being the same as the one end of the first screw rotor to which the rotary shaft of the power source is connected; a third liquid supply port provided in the casing for supplying the lubricating liquid to the second bearing, The third liquid supply port is A lubricating oil supply pipe is formed in the casing so as to supply the lubricating liquid to the first bearing from the screw rotor side.

2. The screw compressor according to claim 1 .

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