JP6675286B2 - Screw compressor - Google Patents

Description

  The present invention relates to a screw compressor, and more particularly, to a lubricating oil supply structure in a screw compressor.

  In a screw compressor, lubricating oil is supplied through an oil flow path to oil supply points such as a bearing that supports a rotor shaft of a screw rotor and a gear mechanism that transmits rotational driving force from a motor to the rotor shaft. After the lubricating oil supplied to each lubrication point is stored in the oil reservoir, the lubricating oil cooled by the oil cooler by the oil pump is again supplied to each lubrication point.

  In the screw compressor, the arrangement and the configuration are made centering on the compressor main body, the priority of the arrangement place of the oil cooler is low, and the screw cooler is often arranged in a place away from the compressor main body. In particular, in the case of a packaged screw compressor, space is greatly restricted, and it is necessary to store various components in a limited space. Therefore, the compressor body is preferentially arranged, and an oil cooler is often arranged in the remaining space after that. Due to such circumstances, the oil cooler will be disposed at a location distant from the compressor body.

  Patent Document 1 discloses a packaged screw compressor in which an oil cooler is arranged at a position distant from the compressor body.

JP-A-8-296574

  In a screw compressor, the operation of an oil pump is usually started in synchronization with the start of operation of the compressor body. The lubricating oil sent from the oil pump is supplied to a bearing of the compressor body via an oil cooler. Since the oil cooler is located away from the compressor main body, the flow path length from the oil pump to the bearing of the compressor main body via the oil cooler is long. In a screw compressor having a long flow path length, even when the operation of the compressor main body is started, lubrication of the bearing of the compressor main body is not performed immediately, so that lubrication of the bearing becomes insufficient. Therefore, there is a possibility that the bearing of the compressor body may not function properly at the start of operation.

  Therefore, a technical problem to be solved by the present invention is to provide a screw compressor in which the oil supply to the bearings of the compressor main body is immediately performed in accordance with the start of operation of the compressor main body.

  According to the present invention, in order to solve the above technical problem, the following screw compressor is provided.

  That is, a screw rotor housed in a main body casing of the compressor body, a bearing for supporting a rotor shaft of the screw rotor, a motor for rotating the rotor shaft, and a lubricating oil An oil pump that starts feeding, a cooling flow path that cools the lubricating oil sent from the oil pump by an oil cooler, and a supply flow path that is located downstream of the cooling flow path and supplies at least the bearing with oil. A bypass flow path branched from the cooling flow path on the upstream side of the oil cooler and joined to the cooling flow path on the downstream side of the oil cooler and connected to the supply flow path; And a bypass passage for supplying the bearing with the lubricating oil delivered from the bearing without passing through the oil cooler. To. Note that the oil pump may be driven by the power transmitted from the motor to rotate.

  According to the above configuration, in the flow path including the bypass flow path, the flow path length from the oil pump to the bearing of the compressor body is relatively shorter than other flow paths including the cooling flow path. Therefore, oil supply to the bearings of the compressor main body is immediately performed in accordance with the start of operation of the compressor main body. As a result, the bearing contains an appropriate amount of lubricating oil, and the bearing functions normally immediately after starting operation.

FIG. 1 is a schematic longitudinal sectional view of a screw compressor according to a first embodiment of the present invention. The typical longitudinal section of the screw compressor concerning a 2nd embodiment of this invention. The typical longitudinal section of the screw compressor concerning a 3rd embodiment of this invention.

  First, a screw compressor 1 according to a first embodiment of the present invention will be described in detail with reference to FIG.

  The screw compressor 1 is, for example, a package-type screw compressor 1 housed in a package indicated by a dashed line. In the package type screw compressor 1, various components are accommodated in the package, and the fan is driven to suck air from the air inlet 55 and discharge the sucked air from the air outlet 56. The screw compressor 1 includes a compressor main body 2, a motor 3, an oil cooler 4 for cooling lubricating oil, a gas cooler for cooling compressed gas (not shown), a control unit (not shown) for controlling the operation of the screw compressor 1, And various components such as an oil flow path 8.

  The compressor main body 2 is, for example, an oil-free screw compressor having a pair of male and female screw rotors 22 meshed with each other and housed in a rotor chamber of a main body casing 21. A rotor shaft 26 is provided at one end and the other end of each screw rotor 22. Each rotor shaft 26 on one end side is rotatably supported by a first bearing 23. Each rotor shaft 26 at the other end is rotatably supported by a second bearing 24. A timing gear 25 is attached to each of the rotor shafts 26 on one end side. A driven gear 27 is attached to one of the other ends of the rotor shaft 26. The driven gear 27 meshes with a drive gear 32 attached to a rotary drive shaft 31 connected to a motor shaft.

  The rotational driving force of the motor 3 is transmitted to one screw rotor 22 via the driving gear 32 and the driven gear 27. Then, the rotational driving force transmitted to one screw rotor 22 is transmitted to the other screw rotor 22 via the timing gear 25. Thus, the pair of screw rotors 22 rotate synchronously in a non-contact state.

  The other end of the main casing 21 is connected to the gear box 28. The driven gear 27 and the driving gear 32 described above are housed in the gear box 28. An oil reservoir 33 for storing lubricating oil is provided at a lower portion of the gear box 28. An oil passage 8 for circulating lubricating oil between the oil reservoir 33 and a lubrication point requiring lubrication is connected to the gear box 28. An oil pump 34, an oil cooler 4, an oil filter 41, and the compressor main body 2 are provided on the oil flow path 8 connected to the gear box 28.

  The lubricating oil stored in the oil sump 33 is sent out to the pump channel 9 by the oil pump 34. The oil pump 34 may be any oil pump that starts sending the lubricating oil in accordance with the start of driving of the motor 3, that is, the start of operation of the compressor body 2. It is desirable that the start of the supply of the lubricating oil by the oil pump 34 be substantially simultaneous with the start of the operation of the motor 3 or slightly earlier than the start of the operation of the motor 3. The oil pump 34 is driven to rotate by the rotation drive shaft 31, but is not limited to the one driven by the power transmitted from the motor 3 that drives the compressor body 2 to be driven to rotate. A configuration in which the motor 3 is driven to rotate by an independent motor separate from the motor 3 may be employed.

  The oil cooler 4 is air-cooled for cooling lubricating oil by a flow of air generated by a cooling fan provided near the oil cooler 4 or a cooling fan provided in a package and away from the oil cooler 4. It is of the formula. The cooling fan is driven by a separate motor independent of the motor 3.

  The oil passage 8 is configured to supply the lubricating oil sent from the oil pump 34 to various lubrication points in the compressor body 2 that require lubrication, and then return the lubricating oil to the oil sump 33 of the gear box 28. I have. Thus, the lubricating oil is configured to circulate through the screw compressor 1. The oil flow path 8 includes a first flow path 61 connecting the pump flow path 9, the cooling flow path 11, the supply flow path 14, and the discharge flow path 18, and the pump flow path 9, the bypass flow path 51, and the supply flow path 14. A second route 62 connecting the discharge passage 18 and the discharge passage 18. Comparing the first route 61 and the second route 62, the difference is that the first route 61 has the cooling flow channel 11 and the second route 62 has the bypass flow channel 51. Are common. The downstream side of the pump flow path 9 is branched at the branch point 37 into the cooling flow path 11 and the bypass flow path 51. The downstream sides of the cooling flow path 11 and the bypass flow path 51 join at the junction 38 and are connected to the supply flow path 14.

  The pump passage 9 connects the lower part of the oil reservoir 33 and the branch point 37, and an oil pump 34 is provided on the pump passage 9. The cooling passage 11 connects the branch point 37 and the junction point 38, and the oil cooler 4 is provided on the cooling passage 11. In the present embodiment, a cooling jacket 29 is provided on the cooling channel 11 downstream of the oil cooler 4. The supply flow path 14 connects the junction point 38 to each of the oil supply points of the compressor body 2, and an oil filter 41 is provided on the supply flow path 14 downstream of the junction point 38. Clean lubricating oil from which foreign matter and the like have been removed by the oil filter 41 is supplied to the first bearing 23 and the second bearing 24. The supply channel 14 includes a first bearing channel 15, a second bearing channel 16, and a gear channel 17 that are further branched on the downstream side of the oil filter 41. The discharge passage 18 connects the first bearing 23 and the second bearing 24 to the upper part of the oil reservoir 33.

  In the screw compressor 1 shown in FIG. 1, the first bearing 23 and the second bearing 24 of the compressor main body 2 pass through the first bearing passage 15 and the second bearing passage 16 which constitute a part of the supply passage 14. Is supplied with lubricating oil. Further, the lubricating oil is supplied to the driven gear 27 and the drive gear 32 of the gear box 28 through the gear flow path 17 which forms a part of the supply flow path 14. As described above, the lubricating oil is supplied to the first bearing 23, the second bearing 24, the driven gear 27, and the drive gear 32 of the compressor main body 2 through the supply passage 14 (hereinafter, these are referred to as oil supply points of the compressor main body 2). .).

  Further, lubricating oil is supplied to the cooling jacket 29 provided in the main body casing 21 through the cooling channel 11. The main casing 21 is cooled by the lubricating oil flowing through the cooling jacket 29. The cooling structure is simplified and the cost is reduced as compared with the case where a flow path for cooling the cooling jacket 29 is separately provided.

  The lubricating oil cooled via the oil cooler 4 arranged at a position distant from the compressor main body 2 is supplied to the oil supply point of the compressor main body 2 by the first route 61 including the cooling flow path 11. Therefore, lubricating oil having good lubrication performance is supplied to the oil supply point of the compressor body 2. However, in the first route 61 including the cooling channel 11, the length of the channel from the oil pump 34 to the oil supply point of the compressor body 2 is relatively long by the oil cooler 4.

  On the other hand, as described above, the bypass flow path 51 of the second route 62 branches at the branch point 37 located downstream of the oil pump 34, merges at the merge point 38, and then connects to the supply flow path 14. Have been. Therefore, lubricating oil that does not pass through the oil cooler 4 is supplied to the oil supply point of the compressor body 2. In the second route 62 including the bypass passage 51, the passage length from the oil pump 34 to the oil supply point of the compressor body 2 is relatively short because the oil does not pass through the oil cooler 4.

  According to the oil supply structure, oil supply to the compressor body 2, that is, oil to the first bearing 23 and the second bearing 24, is performed in accordance with the start of operation of the motor 3, that is, the start of operation of the compressor main body 2. Will be done immediately through. As a result, the first bearing 23 and the second bearing 24 contain an appropriate amount of lubricating oil, and the first bearing 23 and the second bearing 24 function normally immediately after the start of operation.

  Preferably, the cross-sectional area of the cooling flow path 11 is configured to be larger than the cross-sectional area of the bypass flow path 51. For example, the cross-sectional area of the cooling flow path 11 is configured to be approximately ten times as large as the cross-sectional area of the bypass flow path 51. Further, the internal volume of the cooling channel 11 is configured to be larger than the internal volume of the bypass channel 51. For example, the internal volume of the cooling channel 11 is configured to be approximately 100 times or more the internal volume of the bypass channel 51. According to this configuration, a large amount of cooled lubricating oil flows through the cooling channel 11, and an appropriate amount of lubricating oil flows through the bypass channel 51 to lubricate the lubrication point. As a result, immediately after the start of operation, the lubrication points of the compressor main body 2, that is, the first bearing 23 and the second bearing 24 are lubricated with an appropriate amount of lubricating oil from the bypass passage 51. After a short period of time has elapsed from the start of operation, the lubrication oil of the compressor body 2, that is, the first bearing 23 and the second bearing 23, is supplied with a large amount of lubricating oil cooled by the cooling passage 11 in addition to the bypass passage 51. 24 are lubricated. For example, when the screw compressor 1 is operated under the condition that the temperature of the lubricating oil is 0 ° C. or less, the time from the start of operation to the time when the first bearing 23 and the second bearing 24 are supplied with oil (bearing oil supply time) is a bypass time. A result is obtained that it is reduced to about two thirds of the case without the flow path 51.

  Next, a screw compressor 1 according to a second embodiment of the present invention will be described in detail with reference to FIG. In the second embodiment, components having the same functions as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

  In the second embodiment, a temperature control valve 43 is provided on the bypass channel 51. Normally, the temperature of the lubricating oil immediately after the start of operation is low, but the temperature of the lubricating oil gradually increases as the operation time increases. The lubricating oil flowing through the cooling passage 11 is cooled to a predetermined temperature or lower by passing through the oil cooler 4. Since the lubricating oil flowing through the bypass flow path 51 does not pass through the oil cooler 4, the lubricating oil supplied through the bypass flow path 51 tends to have a high temperature. When the temperature of the lubricating oil becomes high, the lubricating performance deteriorates. Therefore, there is a possibility that lubricating oil having deteriorated lubricating performance is supplied to the lubrication point of the compressor main body 2, that is, the first bearing 23 and the second bearing 24 through the bypass passage 51.

  Therefore, a temperature control valve 43 that closes the bypass flow passage 51 when the lubricating oil flowing through the bypass flow passage 51 exceeds a predetermined temperature is provided on the bypass flow passage 51. The predetermined temperature used for opening and closing the temperature control valve 43 is lower than the temperature at which the lubricating performance of the lubricating oil deteriorates. As a number that does not limit the present invention, the predetermined temperature used for opening and closing the temperature control valve 43 is, for example, 65 ° C. to 75 ° C. Although the relatively low-temperature lubricating oil immediately after the start of the operation flows through the bypass flow path 51 due to the temperature control valve 43, the lubricating oil that has become relatively high after a short time from the operation start flows through the bypass flow path 51. Without flowing through the cooling channel 11. Therefore, it is possible to prevent the lubricating oil, whose lubricating performance has been deteriorated due to the high temperature, from being supplied to the lubrication point of the compressor body 2, that is, the first bearing 23 and the second bearing 24.

  The temperature control valve 43 in the second embodiment shown in FIG. 2 is a self-standing type temperature control valve 43 that opens and closes by itself in accordance with the temperature of lubricating oil flowing through the bypass passage 51 and passing through the inside of the valve. . The self-standing temperature control valve 43 is, for example, a wax-type temperature control valve 43 in which a wax that rapidly changes in volume according to the temperature is sealed in a hollow valve body. The wax-type temperature control valve 43 opens and closes the valve autonomously (autonomously) when the wax rapidly changes in volume at a predetermined temperature. The wax-type temperature control valve 43 does not require a temperature sensor that measures the temperature of the lubricating oil and a control unit that controls opening and closing of the temperature control valve 43. Therefore, regarding opening / closing control in the bypass channel 51, size reduction and cost reduction can be achieved. Further, as the self-standing type temperature control valve 43, a valve using a temperature-sensitive spring made of a shape memory alloy can be used.

  Next, a screw compressor 1 according to a third embodiment of the present invention will be described in detail with reference to FIG. In the third embodiment, components having the same functions as the components in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

  In the third embodiment, the on-off valve 45 provided on the bypass flow path 51, the temperature sensor 44 provided in the oil reservoir 33, and the valve control unit 46 for controlling the on-off of the on-off valve 45 are used for bypass. The flow of the lubricating oil in the flow path 51 is controlled. After the lubricating oil supplied to the oil supply point of the compressor main body 2 is stored in the oil sump 33, a part of the lubricating oil is supplied again to the oil supply point of the compressor main body 2 through the bypass passage 51. Since the lubricating oil flowing through the bypass passage 51 is not cooled by the oil cooler 4, the temperature of the lubricating oil is close to the temperature of the lubricating oil in the oil sump 33 and may be considered to be substantially equivalent. it can. Therefore, the temperature of the lubricating oil in the oil reservoir 33 is measured by the temperature sensor 44 as a predetermined temperature used to open and close the on-off valve 45.

  The operation of the actuator of the on-off valve 45 is controlled by the valve control unit 46 based on the measured temperature of the lubricating oil, and the opening and closing of the on-off valve 45 is controlled. The on-off valve 45 is configured to close the bypass passage 51 when the lubricating oil flowing through the bypass passage 51 exceeds a predetermined temperature. That is, the opening and closing of the on-off valve 45 is controlled by the valve control unit 46 in accordance with the temperature of the oil reservoir 33 that is substantially equal to the temperature of the lubricating oil flowing through the bypass passage 51. Therefore, the setting of the predetermined temperature used for opening and closing the on-off valve 45 can be arbitrarily and easily changed by the valve control unit 46, so that the change of the predetermined temperature can be quickly and easily handled.

  The present invention is also applicable to an oil-cooled screw compressor that supplies lubricating oil to a rotor chamber that compresses gas with the screw rotor 22 for the purpose of sealing and cooling. Further, as a cooling method of the lubricating oil, an air cooling type in which the oil cooler 4 is cooled by a cooling fan has been illustrated, but a water cooling type in which the oil cooler 4 is cooled by cooling water supplied by a water pump may be used. In addition, in order to explain the present invention, the mode in which the oil pump 34 starts to supply the lubricating oil in synchronization with the start of driving of the motor 3, that is, the start of operation of the compressor body 2 has been described. A mode in which the oil pump 34 starts sending out the lubricating oil slightly later than the above may be included. That is, there may be a slight (about several seconds) time lag between the start of driving the motor 3 and the start of lubricating oil delivery by the oil pump 34.

  In order to explain the present invention, a package-type screw compressor in which various components such as the compressor main body 2, the motor 3, the oil cooler 4, and the control unit are housed in a package has been exemplified. The present invention can also be applied to a conventional screw compressor in which is not housed in a package.

As is clear from the above description, the screw compressor 1 according to the present invention has:
A screw rotor 22 housed in a main body casing 21 of the compressor main body 2,
Bearings 23 and 24 for supporting a rotor shaft 26 of the screw rotor 22;
A motor 3 for rotationally driving the rotor shaft 26;
An oil pump 34 for starting delivery of lubricating oil in accordance with the start of driving of the motor 3;
A cooling passage 11 for cooling the lubricating oil sent from the oil pump 34 by the oil cooler 4,
Supply passages 15, 16 for supplying oil to at least the bearings 23, 24, located downstream of the cooling passage 11;
A bypass flow path 51 branched from the cooling flow path 11 upstream of the oil cooler 4 and joined to the cooling flow path 11 downstream of the oil cooler 4 and connected to the supply flow paths 15 and 16. And a bypass passage 51 for supplying lubricating oil sent from the oil pump 34 to the bearings 23 and 24 without passing through the oil cooler 4.

  According to the above configuration, in the flow path including the bypass flow path 51, the flow path length from the oil pump 34 to the bearings 23 and 24 of the compressor body 2 is relatively longer than other flow paths including the cooling flow path 11. Has become shorter. Therefore, oil supply to the bearings 23 and 24 of the compressor main body 2 is immediately performed at the same time as the operation start of the compressor main body 2. As a result, the bearings 23 and 24 contain an appropriate amount of lubricating oil, and the bearings 23 and 24 function normally immediately after the start of operation.

  The present invention can have the following features in addition to the above features.

  That is, a cooling jacket 29 provided in the main body casing 21 of the compressor main body 2 is provided on the cooling flow path 11 downstream of the oil cooler 4. According to this configuration, the cooling structure is simplified and the cost is reduced as compared with the case where a flow path for cooling the cooling jacket 29 is separately provided.

  A temperature control valve 43 that closes the bypass flow passage 51 when the lubricating oil flowing through the bypass flow passage 51 exceeds a predetermined temperature is provided on the bypass flow passage 51. According to this configuration, the relatively low-temperature lubricating oil immediately after the start of the operation flows through the bypass passage 51, but the lubricating oil that has become relatively high after a short time from the start of the operation flows through the bypass passage 51. Without flowing through the cooling channel 11. Therefore, it is possible to prevent the lubricating oil whose lubrication performance has been deteriorated due to the high temperature from being supplied to the bearings 23 and 24.

  The temperature control valve 43 is a self-standing temperature control valve that opens and closes by itself in accordance with the temperature of the lubricating oil passing through the inside. According to this configuration, since a temperature sensor and a control unit are not required, the size and cost can be reduced with respect to the opening / closing configuration in the bypass flow path 51.

  An on-off valve 45 for closing the bypass flow passage 51 when the lubricating oil flowing through the bypass flow passage 51 exceeds a predetermined temperature is provided on the bypass flow passage 51. According to this configuration, the relatively low-temperature lubricating oil immediately after the start of the operation flows through the bypass passage 51, but the lubricating oil that has become relatively high after a short time from the start of the operation flows through the bypass passage 51. Without flowing through the cooling channel 11. Therefore, it is possible to prevent the lubricating oil whose lubricating performance has been deteriorated due to the high temperature from being supplied to the bearings 23 and 24.

  The opening and closing of the on-off valve 45 is controlled by the valve control unit 46 according to the temperature of the oil reservoir 33 that is substantially equal to the temperature of the lubricating oil flowing through the bypass flow path 51. According to this configuration, the setting of the predetermined temperature used for opening and closing the on-off valve 45 can be arbitrarily and easily changed by the valve control unit 46, so that the predetermined temperature can be changed quickly and easily.

Further, the screw compressor 1 according to the present invention includes:
A screw rotor 22 housed in a main body casing 21 of the compressor main body 2,
Bearings 23 and 24 for supporting a rotor shaft 26 of the screw rotor 22;
A motor 3 for rotationally driving the rotor shaft 26;
An oil pump 34 that is rotationally driven by power transmitted from the motor 3,
A cooling passage 11 for cooling the lubricating oil sent from the oil pump 34 by the oil cooler 4,
Supply passages 15, 16 for supplying oil to at least the bearings 23, 24, located downstream of the cooling passage 11;
A bypass flow path 51 branched from the cooling flow path 11 upstream of the oil cooler 4 and joined to the cooling flow path 11 downstream of the oil cooler 4 and connected to the supply flow paths 15 and 16. And a bypass passage 51 for supplying lubricating oil sent from the oil pump 34 to the bearings 23 and 24 without passing through the oil cooler 4.

  According to the above configuration, in the flow path including the bypass flow path 51, the flow path length from the oil pump 34 to the bearings 23 and 24 of the compressor body 2 is relatively longer than other flow paths including the cooling flow path 11. Has become shorter. Therefore, oil supply to the bearings 23 and 24 of the compressor body 2 is immediately performed at the same time as the drive of the motor 3 is started. As a result, the bearings 23 and 24 contain an appropriate amount of lubricating oil, and the bearings 23 and 24 function normally immediately after the start of operation.

  It should be understood that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments, and includes all modifications within the scope and meaning equivalent to the terms of the claims.

1: Package type screw compressor 2: Compressor body 3: Motor 4: Oil cooler 8: Oil flow path 9: Pump flow path 11: Cooling flow path 14: Supply flow path 15: First bearing flow path (supply flow Road)
16: second bearing flow path (supply flow path)
17: Gear channel (supply channel)
18: discharge passage 21: main body casing 22: screw rotor 23: first bearing (bearing)
24: second bearing (bearing)
25: timing gear 26: rotor shaft 27: driven gear 28: gear box 29: cooling jacket 31: rotary drive shaft 32: drive gear 33: oil reservoir 34: oil pump 37: branch point
38: Merging point 41: Oil filter 43: Temperature control valve 44: Temperature sensor 45: Open / close valve 46: Valve control unit 51: Bypass channel 55: Air inflow unit 56: Air outflow unit 61: First route 62: Second root

Claims (6)

A screw rotor housed in a body casing of the compressor body,
A bearing that supports a rotor shaft of the screw rotor;
A motor that rotationally drives the rotor shaft,
An oil pump that starts sending lubricating oil in accordance with the start of driving of the motor,
A cooling passage for cooling the lubricating oil sent from the oil pump by an oil cooler,
A cooling jacket provided on a cooling flow path downstream of the oil cooler and disposed on a main body casing of the compressor main body;
A supply flow path that is located downstream of the cooling flow path and supplies oil to at least the bearing,
A bypass flow path branched from the cooling flow path upstream of the oil cooler and joined to the cooling flow path downstream of the oil cooler and downstream of the cooling jacket and connected to the supply flow path; And a bypass passage for supplying lubricating oil sent from the oil pump to the bearing without passing through the oil cooler and the cooling jacket ,
A screw compressor , wherein a cross-sectional area and an internal volume of the cooling channel are larger than a cross-sectional area and an internal volume of the bypass channel . The screw compressor according to claim 1 ,
A screw compressor, wherein a temperature control valve for closing the bypass flow passage when lubricating oil flowing through the bypass flow passage exceeds a predetermined temperature is provided on the bypass flow passage. The screw compressor according to claim 2 ,
A screw compressor, wherein the temperature control valve is a self-standing type temperature control valve that opens and closes by itself in accordance with the temperature of lubricating oil passing through the inside. The screw compressor according to claim 1 ,
A screw compressor, wherein an on-off valve for closing the bypass passage when lubricating oil flowing through the bypass passage exceeds a predetermined temperature is provided on the bypass passage. The screw compressor according to claim 4 ,
A screw compressor, wherein opening and closing of the on-off valve is controlled by a valve control unit in accordance with a temperature of an oil reservoir that is substantially equal to a temperature of lubricating oil flowing through the bypass flow passage. A screw rotor housed in a body casing of the compressor body,
A bearing that supports a rotor shaft of the screw rotor;
A motor that rotationally drives the rotor shaft,
An oil pump driven to rotate by being transmitted from the motor;
A cooling passage for cooling the lubricating oil sent from the oil pump by an oil cooler,
A cooling jacket provided on a cooling flow path downstream of the oil cooler and disposed on a main body casing of the compressor main body;
A supply flow path that is located downstream of the cooling flow path and supplies oil to at least the bearing,
A bypass flow path branched from the cooling flow path upstream of the oil cooler and joined to the cooling flow path downstream of the oil cooler and downstream of the cooling jacket and connected to the supply flow path; And a bypass passage for supplying lubricating oil sent from the oil pump to the bearing without passing through the oil cooler and the cooling jacket ,
A screw compressor , wherein a cross-sectional area and an internal volume of the cooling channel are larger than a cross-sectional area and an internal volume of the bypass channel .

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