JPH05113184A - Screw compressor - Google Patents

Abstract

PURPOSE:To reduce the obstruction for the suction of a rotor by reducing the inflow of lubricating oil to the suction side of the rotor by forming an oil supplying passage which communicates to a high pressure side bearing, at a sealing part between an edge part chamber having a high pressure side bearing installed and the high pressure part of the rotor. CONSTITUTION:A screw rotor 2 having a screw groove 21 is installed in the casing 1 of a screw compressor, and a suction side chamber 31 having a low pressure side bearing 3 installed and a high pressure side edge part chamber 5 in which a bearing housing 51 supporting a high pressure side bearing 4 are formed. A sealing part 7 is formed by fitting the bearing housing 51 and the rotor 2 each other, and an oil supplying passage which communicates to the high pressure side bearing 4 is opened. The lubricating oil which leaks from the sealing part 7 is allowed to flow to the high pressure side bearing side 4 from the oil supplying passage 8. The lubricating oil which flows into the suction side of the rotor 2 reduces by that portion, and the increase of the specific capacity of the sucked gas due to the overheat of the lubricating oil and the gasification of coolant are reduced. Accordingly, the reduction of the capacity efficiency due to the obstruction for the suction to the rotor 2 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw compressor, and more particularly to a casing, a screw rotor rotatably supported in the casing, and a low pressure side bearing and a high pressure side bearing for supporting a drive shaft of the screw rotor. The present invention relates to a screw compressor in which a high-pressure side end chamber containing the high-pressure side bearing is partitioned from a high-pressure part of the rotor via a seal portion and the high-pressure side end chamber communicates with a suction side.

[0002]

2. Description of the Related Art Conventionally, this type of screw compressor is disclosed in, for example, Japanese Patent Publication No. 28682/1990, and FIG.
As shown in FIG. 3, a casing A is internally provided with a screw rotor C having a screw groove B, and a drive shaft D of the screw rotor C is rotatably supported by a low pressure side bearing E and a high pressure side bearing F. A seal portion G made of a labyrinth is provided on the outer periphery of the cylindrical portion of the rotor C to partition the high pressure portion formed in the screw groove B during rotation of the rotor C and the high pressure side bearing F side. ..

Lubricating oil separated by an oil separator (not shown) provided on the discharge side of the casing A is supplied to each bearing E,
In addition to supplying oil to F, a pressure equalizing passage H is provided in the rotor C so that the high pressure side bearing F side communicates with the suction side of the rotor C to equalize pressure with the suction side.

[0004]

However, in the above configuration, the lubricating oil that lubricates the low pressure side bearing E is the rotor C.
Of the high pressure side bearing F, and the lubricating oil that lubricates the high pressure side bearing F also flows from the high pressure portion formed in the screw groove B to the high pressure side bearing F side through the seal portion G. The leaked lubricating oil and refrigerant gas flow into the suction side of the rotor C through the pressure equalizing passage H, and are separated by the oil separator as described above.
Since the temperature of the lubricating oil supplied to the bearings E and F and the refrigerant gas contained in the lubricating oil is high, when the lubricating oil and the refrigerant gas flow into the suction side, they are sucked by these lubricating oils. When the gas is overheated and expanded, the specific volume of the suction gas is increased, and a part of the refrigerant contained in the lubricating oil is vaporized and gasified, so that the suction inhibition to the rotor C occurs and the volume is increased. There was a problem that the efficiency was lowered and the performance of the compressor could not be improved.

The present invention was invented paying attention to the lubricating oil leaking from the seal portion. An object of the first invention is to lubricate the high pressure side bearing by utilizing the lubricating oil leaking from the seal portion. The point is to improve the performance of the compressor by reducing the overheating of the intake gas due to the high temperature lubricating oil and the gasification of the refrigerant contained in the lubricating oil to reduce the obstruction of the intake to the rotor.

The second object of the present invention is to lubricate the high pressure side and low pressure side bearings by utilizing the lubricating oil leaking from the seal portion, so that the intake gas overheated by the high temperature lubricating oil and the gasification of the refrigerant can be further suppressed. This is to reduce the suction inhibition to the rotor to further improve the performance of the compressor.

[0007]

A first aspect of the present invention is directed to a casing 1, a screw rotor 2 rotatably supported in the casing 1, and a low pressure side bearing 3 and a high pressure side bearing 3 for supporting a drive shaft 6 of the screw rotor 2. And a high pressure side end chamber 5 that houses the high pressure side bearing 4 is partitioned from the high pressure portion of the rotor 2 via a seal portion 7, and the high pressure side end chamber 5 is communicated with the suction side. In the screw compressor, an oil supply passage 8 communicating with the high pressure side bearing 4 is opened in the seal portion 7.

The second invention comprises a casing 1, a screw rotor 2 rotatably supported in the casing 1, and a low pressure side bearing 3 and a high pressure side bearing 4 for supporting a drive shaft 6 of the screw rotor 2, In the screw compressor, which divides the high-pressure side end chamber 5 containing the high-pressure side bearing 4 from the high-pressure part of the rotor 2 through the seal portion 7, and makes the high-pressure side end chamber 5 communicate with the suction side, While blocking the communication between the high pressure side end chamber 5 and the suction side, the drive shaft 6 is provided with an oil supply passage 62 to the low pressure side bearing 3, and a communication is provided between the oil supply passage 62 and the high pressure side bearing 4. Passage 10
Is provided to form an oil supply and pressure equalizing system path from the seal portion 7 through the high pressure side end chamber 5 and the high pressure side bearing 4 to the communication passage 10 and the oil supply passage 62.

Further, it is preferable to provide a magnet filter 9 in the high pressure side end chamber 5 upstream of the fluid leaking from the seal portion 7 with respect to the high pressure side bearing 4.

[0010]

In the first aspect of the invention, the lubricating oil leaking from the seal portion 7 flows into the high pressure side bearing 4 side through the oil supply passage 8 and is used for lubrication of the high pressure side bearing 4 before the rotor 2
The lubricating oil leaked from the seal portion 7 is used as compared with the case where the lubricating oil from the oil separator is used to lubricate the high-pressure side bearing 4. The lubricating oil flowing into the side can be reduced. As a result, it is possible to prevent the intake gas from being overheated by the lubricating oil and suppress the increase in the specific volume of the intake gas, and also to reduce the amount of the refrigerant that is vaporized and gasified on the intake side. It is possible to reduce inhibition and prevent a decrease in volumetric efficiency.

Accordingly, while the lubricating oil leaking from the seal portion 7 can be used to lubricate the high pressure side bearing 4, the rotor is caused by the overheating of the suction gas by the high temperature lubricating oil and the gasification of the refrigerant contained in the lubricating oil. It is possible to reduce the obstruction of inhalation into No. 2 and improve the performance of the compressor.

In the second aspect of the present invention, the lubricating oil leaking from the seal portion 7 to the high pressure side end chamber 5 is caused to flow into the oil supply / equal pressure equalizing system passage and is utilized for lubrication of the high pressure side and low pressure side bearings 4, 3. Flow into the intake side of the rotor 2 from the seal portion 7 compared to the first invention in which only the high pressure side end chamber 5 is lubricated by utilizing the lubricating oil leaking from the seal portion 7. It is possible to use less lubricating oil. As a result, it is possible to further prevent the intake gas from being overheated by the lubricating oil and to increase the specific volume of the intake gas, and it is possible to reduce the amount of the refrigerant that is vaporized and gasified on the intake side. It is possible to further reduce inhalation inhibition and prevent a decrease in volumetric efficiency.

Moreover, the high pressure side end chamber 5 and the suction side of the rotor 2 can be pressure-equalized via the oil supply and pressure equalizing system passage.

Therefore, while the lubricating oil leaking from the seal portion 7 can be used to lubricate the high pressure side and low pressure side bearings 4 and 3, the suction gas is overheated by the high temperature lubricating oil and the refrigerant contained in the lubricating oil. Inhalation obstruction to the rotor 2 due to gasification of the above can be further reduced, and the performance of the compressor can be reduced to the first invention in which only the high pressure side bearing 4 is lubricated by utilizing the lubricating oil leaking from the seal portion 7. It can be further improved in comparison. Further, since the high pressure side end chamber 5 and the suction side of the rotor 2 can be pressure-equalized via the oil supply and pressure equalizing system path, the high pressure side end chamber 5 is directly communicated with the suction side of the rotor 2. As in the case of the above, stable operation can be performed.

Further, in the case where a magnet filter 9 is provided in the high pressure side end chamber 5 upstream of the fluid leaking from the seal portion 7 with respect to the high pressure side bearing 4, from the lubricating oil before flowing into the high pressure side bearing 4. Since the iron powder contained in the lubricating oil can be removed, the durability of the high pressure side and low pressure side bearings 4 and 3 can be improved.

[0016]

EXAMPLE A screw compressor shown in FIG. 1 has a screw rotor 2 having a screw groove 21 inside a casing 1 provided with an oil separator 11, and a low pressure side bearing on the suction side of the rotor 2. 3, a suction side chamber 31 for accommodating 3 is provided, and a discharge side of the rotor 2 is provided with a high pressure side end chamber 5 for accommodating a bearing housing 51 supporting the high pressure side bearing 4, and the low pressure side bearing 3 and the high pressure side bearing are provided. 4, a drive shaft 6 of the rotor 2 is rotatably supported, and a motor 22 installed in the casing 1 rotates the drive shaft 6 to rotate the rotor 2 to compress a fluid mainly composed of a gas refrigerant. Then, the oil is discharged to the oil separator 11.

Further, the cylindrical end portion of the rotor 2 and the bearing housing 51 are fitted to each other, and a seal portion 7 made of a labyrinth is formed at the fitted portion,
The high pressure portion formed in the screw groove 21 during the rotation of the above and the high pressure side end chamber 5 are partitioned by the seal portion 7. Further, the rotor 2 is provided with a pressure equalizing passage 23 extending parallel to the drive shaft 6, and the high pressure side end chamber 5 is provided on the suction side of the rotor 2 via the pressure equalizing passage 23. It is connected to 31.

Reference numeral 61 is a thrust receiving portion provided at the end of the drive shaft 6, and 12 is a partition wall for partitioning the interior of the casing 1 and the interior of the oil separator 11.

In the screw compressor constructed as described above, the seal portion 7 is provided with the high pressure side bearing 4
The oil supply passage 8 communicating with is opened.

That is, as shown in an enlarged manner in FIG. 2, the cylindrical end portion of the rotor 2 and the step portion 52 of the bearing housing 51 are brought into close contact with each other, and an oil sump is provided at the close end of the seal portion 7. While providing the portion 71, the bearing housing 51,
The oil supply passage 8 that opens to the oil sump 71 and extends along the casing 1 is provided, and the tip end side of the oil supply passage 8 is opened near the partition wall 12 in the high pressure side end chamber 5 to provide the oil supply. The passage 8 is communicated with the high pressure side bearing 4.

Further, a magnet filter 9 is provided in the high pressure side end chamber 5 and near the opening of the oil supply passage 8, and a fluid containing a mixture of lubricating oil and refrigerant gas leaking from the seal portion 7 The iron powder contained in the lubricating oil can be removed.

Further, in the embodiment shown in FIG. 1, the drive shaft 6 is provided with an oil supply passage 62 communicating with the low pressure side bearing 3, and the partition wall 12 is provided with the oil supply passage 62 as shown by a chain line. An oil supply path is provided through which lubricating oil flows from the oil sump chamber 13 communicating with the separator 11 to the high pressure side bearing 4 and the oil supply passage 62, so that the high pressure side bearing 4 and the low pressure side bearing 3 can be supplied with oil.

The flow rate of the lubricating oil flowing from the oil supply passage 8 to the high pressure side bearing 4 is, for example, about 40 to 50 cc per minute, and the high pressure side bearing 4 is the lubricating oil that leaks from the seal portion 7. Since it is sufficient to lubricate oil, it is not necessary to supply oil from the oil sump chamber 13 to the high pressure side bearing 4, but the oil supply path is provided on the high pressure side in order to compensate for the lack of lubricating oil leaking from the seal portion 7. It is preferable to communicate with the bearing 4. In this case, the amount of oil supplied to the high pressure side bearing 4 is small enough to compensate for the shortage.

According to the screw compressor of the first embodiment configured as described above, the lubricating oil that leaks from the seal portion 7 and accumulates in the oil sump 71 flows from the oil sump 71 to the oil supply passage 8. After that, the high pressure side bearing 4 can flow into the partition wall 12 side to lubricate the high pressure side bearing 4, and the lubricating oil that has lubricated the high pressure side bearing 4 can flow from the high pressure side end chamber 5 It flows into the suction side chamber 31, that is, the suction side of the rotor 2 through the pressure equalizing passage 23,
Although a part of the refrigerant contained in the lubricating oil is vaporized and gasified, the lubricating oil accumulated in the oil sump chamber 13 is supplied to the high pressure side bearing 4 through the oil supply path to supply the high pressure side bearing. Four
The amount of lubricating oil flowing into the suction side chamber 31 via the pressure equalizing passage 23 is reduced by utilizing the lubricating oil leaking from the seal portion 7 to the oil sump portion 71 as compared with the case where the lubricating oil is lubricated. You can do it. Therefore, it is possible to prevent the intake gas from being overheated by the lubricating oil and to prevent the specific volume of the intake gas from increasing, and also to reduce the amount of the refrigerant that is vaporized and gasified on the intake side. It is possible to reduce the inhalation inhibition to and to prevent the volumetric efficiency from decreasing.

That is, since the high pressure side bearing 4 is lubricated by utilizing the lubricating oil leaking from the seal portion 7, it is possible to eliminate or reduce the supply of the high temperature lubricating oil from the oil sump chamber 13. Therefore, it is possible to reduce overheating of the intake gas due to the high-temperature lubricating oil and the obstruction of intake to the rotor 2 due to gasification of the refrigerant contained in the lubricating oil, and it is possible to improve the performance of the compressor.

Further, the oil supply passage 8 is connected to the high pressure side end chamber 5
Since the magnet filter 9 is provided in the vicinity of the opening, the iron powder contained in the lubricating oil can be removed from the lubricating oil before flowing into the high pressure side bearing 4 from the oil supply passage 8. The durability of the high pressure side bearing 4 can be improved.

As described above, in the first embodiment shown in FIGS. 1 and 2, the high pressure side bearing 4 is lubricated by utilizing the lubricating oil leaking from the seal portion 7. The low pressure side bearing 3 may be lubricated.

Next, the second embodiment will be described with reference to FIG. First, in the first embodiment, the pressure equalizing passage 23 is provided in the rotor 2 so that the high pressure side end chamber 5 and the suction side chamber 31 provided on the suction side of the rotor 2 are directly communicated with each other. In the second embodiment shown in FIG. 5, the pressure equalizing passage 23 is not provided in the rotor 2, and the direct communication between the high pressure side end chamber 5 and the suction side chamber 31 is cut off via the rotor 3.

Further, as in the first embodiment, the drive shaft 6 is provided with the oil supply passage 62 to the low pressure side bearing 3, and the communication passage 10 is provided between the thrust receiving portion 61 and the partition wall 12. Is provided to connect the oil supply passage 62 and the high-pressure side bearing 4 via the communication passage 10. As shown by the solid line arrow in FIG. 3, the seal portion 7 is connected to the high-pressure side end chamber 5 and the high-pressure side. An oil supply and pressure equalizing system path is formed from the bearing 4 to the communication passage 10 and the oil supply passage 62, and the high pressure side end chamber 5 is communicated with the suction chamber 31, that is, the suction side of the rotor 2.

Further, the magnet filter 9 is provided near the step portion 52 side on the inner peripheral surface of the bearing housing 51, and the fluid leaking from the seal portion 7 and containing a mixture of the refrigerant gas and the refrigerant gas is mixed with the magnet. Filter 9
The iron powder contained in the lubricating oil can be removed by passing through.

Further, as in the first embodiment shown in FIG. 1, it is preferable that the partition wall 12 is provided with an oil supply passage shown by a chain line, and in this case as well, the amount of oil supplied from the oil supply passage is increased. Is small enough to compensate for the shortage of lubricating oil leaking from the seal portion 7.

According to the screw compressor of the second embodiment configured as described above, the seal portion 7 to the seal portion 7 are
The lubricating oil leaking to the high pressure side end chamber 5 through the gap of No. 5 flows as indicated by the solid line arrow, and the lubricating oil leaking from the seal portion 7 to the high pressure side end chamber 5 is After passing through the magnet filter 9 in the end chamber 5, it flows into the high pressure side bearing 4 to lubricate the high pressure side bearing 4. Further, the lubricating oil that lubricates the high pressure side bearing 4 flows into the oil supply passage 62 through the communication passage 10, further flows from the oil supply passage 62 into the low pressure side bearing 3, and the low pressure side bearing 3 It can be lubricated. Further, the lubricating oil that lubricates the low pressure side bearing 3 flows into the suction side chamber 31, that is, the suction side of the rotor 2,
A part of the refrigerant contained in the lubricating oil evaporates and gasifies. When oil is supplied from the oil sump chamber 13 to the high pressure side and low pressure side bearings 4 and 3 via the oil supply path, and
As in the embodiment, only the high pressure side end chamber 5 is lubricated by utilizing the lubricating oil leaking from the seal portion 7, and the low pressure side bearing 3
In comparison with the case of supplying oil from the oil sump chamber 13, the amount of lubricating oil flowing into the suction side chamber 31 can be reduced. Therefore, it is possible to further suppress the increase of the intake gas overheat due to the lubricating oil and increase the specific volume of the intake gas, and it is also possible to reduce the amount of the refrigerant that is vaporized and gasified on the intake side. It is possible to reduce the obstruction of suction to the rotor 2 and prevent the volumetric efficiency from lowering. Moreover, the high pressure side end chamber 5 and the suction side of the rotor 2 can be pressure-equalized via the oil supply / equalization system passage.

As described above, the lubricating oil leaking from the seal portion 7 is used to lubricate the high pressure side and low pressure side bearings 4 and 3, whereby the intake gas is overheated by the high temperature lubricating oil or the lubricating oil is used. Inhibition of suction into the rotor 2 due to gasification of the refrigerant contained in (1) can be further reduced compared to the first embodiment, so the performance of the compressor can be further improved. Further, since the high pressure side end chamber 5 and the suction side of the rotor 2 can be pressure-equalized via the oil supply and pressure equalizing system path, the high pressure side end chamber 5 is directly communicated with the suction side of the rotor 2. In addition, stable operation can be performed as in the first embodiment.

Further, since the magnet filter 9 is provided on the inner peripheral surface of the bearing housing 51 near the step portion 52 side, it leaks from the seal portion 7 to the high pressure side end chamber 5 and the high pressure side bearing. The iron powder contained in the lubricating oil before flowing into the lubricating oil 4 can be removed, and the durability of the high pressure side bearing 4 and the low pressure side bearing 4 can be improved.

[0035]

As described above, according to the first aspect of the present invention, the casing 1, the screw rotor 2 rotatably supported in the casing 1, and the low pressure side bearing 3 and the high pressure side bearing 4 supporting the drive shaft 6 of the screw rotor 2 are provided. A screw for partitioning the high-pressure side end chamber 5 containing the high-pressure side bearing 4 from the high-pressure part of the rotor 2 via a seal portion 7, and for communicating the high-pressure side end chamber 5 with the suction side. In the compressor, since the oil supply passage 8 communicating with the high pressure side bearing 4 is opened in the seal portion 7, the lubricating oil leaking from the seal portion 7 is caused to flow into the high pressure side bearing 4 side through the oil supply passage 8. The lubricant that can be used to lubricate the high-pressure side bearing 4 and leaks from the seal portion 7 as compared with the case where the high-pressure side bearing 4 is lubricated using only the lubricating oil from the oil separator. Use oil It is possible to reduce the lubricating oil flowing only to the suction side of the rotor 2. As a result, it is possible to prevent the intake gas from being overheated by the lubricating oil and suppress the increase in the specific volume of the intake gas, and also to reduce the amount of the refrigerant that is vaporized and gasified on the intake side. It is possible to reduce inhibition and prevent a decrease in volumetric efficiency.

Therefore, while the lubricating oil leaking from the seal portion 7 can be used to lubricate the high pressure side bearing 4, the rotor is caused by the overheating of the suction gas by the high temperature lubricating oil and the gasification of the refrigerant contained in the lubricating oil. It is possible to reduce the obstruction of inhalation into No. 2 and improve the performance of the compressor.

In the second aspect of the invention, the casing 1, the screw rotor 2 that is rotatably supported in the casing 1, and the low pressure side bearing 3 that supports the drive shaft 6 of the screw rotor 2 are provided.
And a high-pressure side bearing 4 are provided, the high-pressure side end chamber 5 that houses the high-pressure side bearing 4 is partitioned from the high-pressure part of the rotor 2 via a seal portion 7, and the high-pressure side end chamber 5 is on the suction side. In the screw compressor in communication with each other, the communication between the high pressure side end chamber 5 and the suction side is blocked, while the drive shaft 6
Is provided with an oil supply passage 62 to the low pressure side bearing 3,
The communication passage 1 is provided between the oil supply passage 62 and the high pressure side bearing 4.
0 is provided to form an oil supply / equalizing system passage from the seal portion 7 through the high pressure side end chamber 5 and the high pressure side bearing 4 to the communication passage 10 and the oil supply passage 62. Lubricating oil that leaks to the side end chamber 5 can be made to flow in the oil supply / equal pressure equalizing system path and can be used not only for lubrication of the high pressure side bearing 4 but also for the low pressure side bearing 3. The lubricating oil flowing into the suction side of the rotor 2 can be further reduced as compared with the first invention in which only the high pressure side end chamber 5 is lubricated by utilizing the lubricating oil. As a result, it is possible to further prevent the intake gas from being overheated by the lubricating oil and to increase the specific volume of the intake gas, and it is possible to reduce the amount of the refrigerant that is vaporized and gasified on the intake side. It is possible to further reduce the inhalation inhibition and prevent a decrease in volumetric efficiency.

Moreover, the high pressure side end chamber 5 and the suction side of the rotor 2 can be pressure-equalized via the oil supply / equalization system passage.

Therefore, while the lubricating oil leaking from the seal portion 7 can be used to lubricate the high pressure side and low pressure side bearings 4 and 3, the intake gas is overheated by the high temperature lubricating oil and the refrigerant contained in the lubricating oil. Inhalation obstruction to the rotor 2 due to gasification of the above can be further reduced, and the performance of the compressor can be reduced to the first invention in which only the high pressure side bearing 4 is lubricated by utilizing the lubricating oil leaking from the seal portion 7. It can be further improved in comparison. Further, since the high pressure side end chamber 5 and the suction side of the rotor 2 can be pressure-equalized via the oil supply and pressure equalizing system path, the high pressure side end chamber 5 is directly communicated with the suction side of the rotor 2. As in the case of the above, stable operation can be performed.

Further, in the case where the magnet filter 9 is provided in the high pressure side end chamber 5 on the upstream side of the fluid leaking from the seal portion 7 with respect to the high pressure side bearing 4, from the lubricating oil before flowing into the high pressure side bearing 4. Since the iron powder contained in the lubricating oil can be removed, the durability of the high pressure side and low pressure side bearings 4 and 3 can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a screw compressor showing an embodiment of a first invention.

FIG. 2 is an enlarged sectional view of a seal portion in FIG.

FIG. 3 is a cross-sectional view of essential parts of a screw compressor showing an embodiment of the second invention.

FIG. 4 is a partial cross-sectional view showing a conventional example.

[Explanation of symbols]

 1 Casing 2 Screw rotor 3 Low pressure side bearing 4 High pressure side bearing 5 High pressure side end chamber 6 Drive shaft 7 Seal part 8 Oil supply passage 9 Magnet filter 10 Communication passage 62 Oil supply passage

Claims (3)

[Claims] 1. A high pressure side bearing comprising a casing 1, a screw rotor 2 rotatably supported in the casing 1 and a low pressure side bearing 3 and a high pressure side bearing 4 which support a drive shaft 6 of the screw rotor 2. High pressure side end chamber 5 that houses 4
In a screw compressor in which the high pressure side end chamber 5 is communicated with the suction side, while partitioning the high pressure side end chamber 5 with the high pressure side of the rotor 2 via the seal portion 7, the seal portion 7 communicates with the high pressure side bearing 4. A screw compressor in which the oil supply passage 8 is opened. 2. A high pressure side bearing comprising a casing 1, a screw rotor 2 rotatably supported in the casing 1 and a low pressure side bearing 3 and a high pressure side bearing 4 for supporting a drive shaft 6 of the screw rotor 2. High pressure side end chamber 5 that houses 4
In the screw compressor in which the high pressure side end chamber 5 is communicated with the high pressure side of the rotor 2 via the seal portion 7, and the high pressure side end chamber 5 is communicated with the suction side. While shutting off, the drive shaft 6 is provided with an oil supply passage 62 to the low pressure side bearing 3, and a communication passage 10 is provided between the oil supply passage 62 and the high pressure side bearing 4.
A screw compressor characterized by forming an oil supply / equalizing system path from the seal portion 7 through the high pressure side end chamber 5 and the high pressure side bearing 4 to the communication passage 10 and the oil supply passage 62. 3. The screw compressor according to claim 1, further comprising a magnet filter 9 provided upstream of the fluid leaking from the seal portion 7 with respect to the high pressure side bearing 4 in the high pressure side end chamber 5.