JP5950870B2 - Oil-cooled screw compressor - Google Patents

Description

  The present invention relates to an oil-cooled screw compressor including a gear chamber that houses a gear mechanism that transmits a rotational driving force from a driving source to a screw.

  The oil-cooled screw compressor includes a compressor body that houses a pair of screw rotors that mesh with each other in a casing, compresses the gas sucked into the rotor chamber from the suction passage by the rotation of the screw rotor, and discharges the gas from the discharge passage. ing. And oil is supplied with respect to various locations of a compressor main part. That is, the oil is supplied to the compression side space of the rotor chamber for the purpose of lubrication, sealing, and cooling of the compressor body.

  A gear chamber that houses a gear mechanism that transmits a rotational driving force from a drive source to any one of the screw rotors and the rotor chamber are connected in a state of being partitioned by a partition wall, An oil-cooled type in which a discharge pipe communicating with the lower part of the rotor chamber is formed in the partition wall, and after oil is supplied to the gear mechanism, it accumulates in the lower part of the gear chamber, and the oil accumulated in the gear chamber is guided to the rotor chamber through the exhaust pipe A screw compressor is disclosed (for example, see Patent Document 1).

  In the oil-cooled screw compressor disclosed in Patent Document 1, the oil contained in the mixed gas is separated by the oil recovery device, and then most of the high-pressure mixed gas containing mist-like oil is transferred to the oil separator. After the oil is removed and sent to the gas outlet, a part of the mixed gas is sent to the return flow path with the removed oil without passing through the filter of the oil separator. Yes. When the gear mechanism is immersed in the oil in the gear chamber, oil agitation occurs, so that there is a problem that the oil temperature rises and power loss for rotating the gear increases. Therefore, high-pressure gas containing oil is introduced into the gear mechanism in the gear chamber through the return flow path connected to the upper space of the gear chamber, so that the gear mechanism is lubricated and the gear chamber is pressurized. Yes. By pressurizing the gear chamber, oil is discharged to the rotor chamber via the discharge pipe and the oil level in the gear chamber is pushed down, so that excessive oil is prevented from accumulating in the gear chamber.

Japanese Utility Model Publication No. 61-138891

  In the screw compressor disclosed in Patent Document 1, a part of the compressed gas compressed in the rotor chamber is used as a pressurizing means for pressurizing the gear chamber. The compressed gas generated by being compressed in the rotor chamber is originally separated from the oil through an oil recovery device or the like and supplied to the compressed gas demand facility. Therefore, when the compressed gas produced | generated by the compressor is used as a pressurizing means of a gear chamber, there exists a problem that the compressed gas supply amount to a compressed gas demand facility decreases.

  Therefore, the technical problem to be solved by the present invention is to supply oil to the gear mechanism in the gear chamber and to use a part of the compressed gas that is being supplied to the compressed gas demand facility via the oil recovery device or the like. It is another object of the present invention to provide an oil-cooled screw compressor provided with pressurizing means that pressurizes the gear chamber and pushes down the oil level in the gear chamber.

  In order to solve the above technical problem, according to the present invention, the following oil-cooled screw compressor is provided.

That is, in the oil-cooled screw compressor according to claim 1 of the present invention,
An oil-cooled screw compressor in which a pair of male and female screw rotors that rotate in a meshing state and compress compressed gas is housed in a rotor chamber of a casing, the oil-cooled screw compressor is
A gear chamber that houses a gear mechanism that transmits a rotational driving force from a driving source to any one of the pair of screw rotors in an airtight state, and the gear chamber is located on the suction side of the casing. The rotor chamber and the liquid reservoir portion of the gear chamber communicate with each other through a communication hole formed in the partition, and the lower end portion of the gear mechanism is connected to the chamber through the communication hole. A gear chamber configured at a higher position,
After supplying approximately discharge pressure of oil to the discharge-side shaft seal portion corresponding to the rotor shaft on the discharge side of the pair of screw rotors, the oil flowing out from the discharge-side shaft seal portion is supplied to the discharge-side bearing portion. A discharge-side oil supply flow path,
A gear chamber oil supply passage for supplying the discharge-side shaft seal / bearing oil that has flowed out of the discharge-side bearing portion to the gear mechanism of the gear chamber.

  In the oil-cooled screw compressor according to claim 2 of the present invention, the oil at the substantially discharge pressure in the discharge side shaft seal portion holds the discharge gas discharged from the rotor chamber by a pressure check valve. It is supplied from an oil sump in an oil separator / collector that is introduced in a state and separates and recovers oil.

  In the oil-cooled screw compressor according to claim 3 of the present invention, the oil at the substantially discharge pressure in the discharge-side shaft seal portion is a gas pressure held in the oil separator / collector from the oil reservoir. It is characterized by being supplied.

  The oil-cooled screw compressor according to claim 4 of the present invention is characterized in that a pressure retaining portion is provided in the gear chamber oil supply passage.

  In the oil-cooled screw compressor according to claim 5 of the present invention, the pressure holding portion is provided immediately before the gear chamber.

  In the oil-cooled screw compressor according to claim 6 of the present invention, the lower end portion of the gear mechanism is configured to be higher than the lower end portion of the screw rotor.

  In the oil-cooled screw compressor according to claim 7 of the present invention, the upper end portion of the communication hole is configured to be higher than the lower end portion of the screw rotor.

  In the invention according to claim 1, the discharge-side shaft seal / bearing oil that seals the shaft seal portion and flows out of the discharge-side bearing portion is housed in the gear chamber in an airtight state via the gear chamber oil supply passage. The mechanism is supplied and the gear mechanism is lubricated. At this time, the discharge-side shaft seal / bearing oil that has been used for the shaft seal and has flowed out of the discharge-side bearing portion contains many fine compressed gas bubbles generated by gas compression. When the bearing oil is introduced into the gear chamber, the compressed gas contained in the discharge side shaft seal / bearing oil expands all at once, increasing the pressure in the gear chamber. Therefore, the oil in the gear chamber is pushed out into the rotor chamber through the communication hole and discharged, and the oil level is lowered, so that excessive oil is prevented from accumulating in the gear chamber. Therefore, lubrication of the gear mechanism and pressurization in the gear chamber can be realized at the same time, and a part of the compressed gas that is being supplied to the compressed gas demand facility through the oil separator / collector etc. is not used. Thus, it is possible to supply more compressed gas to the compressed gas demand facility.

  In the invention according to claim 2, by using the oil in the oil reservoir of the oil separator / recovery unit maintained at a substantially discharge pressure, it is possible to stably secure the oil at a substantially discharge pressure containing a large amount of fine bubbles. There is an effect that can be.

  In the invention according to claim 3, the oil present in the oil reservoir of the retained oil separator / recovery unit is supplied to the ejection side shaft seal portion using the retained gas pressure, thereby providing the discharge side oil supply means. Is not required to be separately provided, and the cost can be reduced.

  The invention according to claim 4 has the effect that the discharge side shaft seal / bearing oil can be kept as high as possible, and the compressed gas contained in the discharge side shaft seal / bearing oil can be prevented from expanding.

  In the invention which concerns on Claim 5, since the pressure output of oil can be maintained so that a pressure holding part is near a gear chamber, there exists an effect that it can lubricate effectively with respect to a gear mechanism.

  In the invention which concerns on Claim 6, since the lower end part of a gear mechanism becomes a position higher than the lower end part of a screw rotor, it is prevented that the oil more than necessary always accumulates in a gear chamber. Therefore, it is possible to prevent the occurrence of energy loss due to agitation during operation of the compressor, and it is possible to suppress energy loss due to agitation during restart, and to more reliably suppress power loss.

  In the invention which concerns on Claim 7, since it has comprised so that the upper end part of a communicating hole may become a position higher than the lower end part of a screw rotor, the oil level in a gear chamber becomes easy to fall to a communicating hole. Therefore, the compressed gas generated in the gear chamber can be quickly sent to the suction side of the rotor chamber without staying more than necessary, and the compressed gas generated in the gear chamber is not wasted.

It is an axial direction horizontal sectional view of the oil-cooling type screw compressor body concerning this invention. It is a principal part enlarged view of FIG. FIG. 2 is a vertical sectional view in the axial direction of the oil-cooled screw compressor body shown in FIG. 1. It is a figure explaining the whole package structure of the oil-cooled type screw compressor concerning this invention.

  Hereinafter, a package-type oil-cooled screw compressor 1 according to an embodiment of the oil-cooled screw compressor according to the present invention will be described in detail with reference to FIGS. In the description of the embodiment, the upstream side and the downstream side mean the suction side and the discharge side, respectively, with reference to the rotor chamber 47 in the compressor body 2.

  First, the compressor body 2 of the oil-cooled screw compressor 1 will be described with reference to FIGS.

  The compressor body 2 of the oil-cooled screw compressor 1 includes a pair of male and female screw rotors 31 and 32 that have helical teeth and mesh with each other, and a casing 30 that houses a pair of male and female screw rotors 31 and 32. And comprising. In the casing 30, the rotor chamber housing 30a and the discharge side housing 30b are integrally coupled by, for example, a bolt (not shown).

  The rotor chamber housing 30a includes a rotor chamber 47 composed of two intersecting cylindrical working spaces that accommodate a pair of male and female screw rotors 31 and 32, and a suction chamber connected to the suction side of the rotor chamber 47. 46 and a suction port 4 provided on the suction side of the suction chamber 46. A portion where the male screw rotor 31 and the female screw rotor 32 mesh with each other constitutes a rotor meshing portion 39 that forms a seal line for sealing compressed gas. By the rotation of the pair of screw rotors 31 and 32, the gas to be compressed (for example, air) is sucked into the rotor chamber 47 through the suction port 4 and the suction port of the suction chamber 46 and compressed. Oil is supplied to the working space of the rotor chamber 47. The oil supplied to the rotor chamber 47 is transferred toward the discharge side of the rotor chamber 47 by the rotation of the pair of male and female screw rotors 31 and 32, and is discharged from the discharge port 5 described later together with the compressed gas.

  A discharge passage 49 is formed in the lower portion of the discharge side housing 30b. The discharge passage 49 has a discharge port 5 that opens toward the center below the discharge side end of the rotor chamber 47. The compressed gas discharged from the discharge port 5 is discharged to the outside of the compressor body 2 through the discharge passage 49, that is, the oil separation and recovery unit 6 (described later in FIG. 4) through the gas discharge passage 13 connected to the discharge passage 49. ).

  The suction-side rotor shaft 33 of the male screw rotor 31 is supported by a suction-side bearing portion 36 provided in the rotor chamber housing 30a, and the discharge-side rotor shaft 33 is supported by a discharge-side bearing portion 37 provided in the discharge-side housing 30b. It is supported. Similarly, the suction-side rotor shaft 34 of the female screw rotor 32 is supported by a suction-side bearing portion 36 provided in the rotor chamber housing 30a, and the discharge-side rotor shaft 34 is provided in the discharge-side housing 30b. Supported by part 37. The rotor shafts 33 and 34 of the screw rotors 31 and 32 are arranged in parallel so as to extend in a substantially horizontal direction.

  A gear device 50 is integrally connected to the end portion on the suction side of the rotor chamber housing 30a. The gear chamber 51 of the gear device 50 is configured to be able to maintain an airtight state, and a gear mechanism 59 is accommodated in the gear chamber 51. The gear mechanism 59 includes a driven gear 57 attached to the suction-side rotor shaft 33 of the male screw rotor 31 and a drive gear 58 attached to the output shaft 35 of the motor 3 as a drive source. The drive gear 57 and the drive gear 58 are meshed. The gear mechanism 59 is configured to transmit the rotational driving force from the output shaft 35 of the motor 3 to one of the male and female screw rotors 31 and 32. For example, as shown in FIG. 1, the gear mechanism 59 is configured to transmit the rotational driving force of the output shaft 35 of the motor 3 to the male screw rotor 31.

  When the output shaft 35 of the motor 3 rotates, the rotor shaft 33 on the suction side of the male screw rotor 31 is rotationally driven via the gear mechanism 59. When the male screw rotor 31 rotates, the female screw rotor 32 is driven by the male screw rotor 31 to be driven. In the gear mechanism 59 in which the driven gear 57 has a small diameter and the driving gear 58 has a large diameter, the rotation of the output shaft 35 of the motor 3 is increased, so that the gear device 50 functions as a speed increasing device.

  The rotor chamber 47 and the gear chamber 51 of the rotor chamber housing 30a are partitioned by a partition wall 54. The partition wall 54 is provided with suction-side bearing portions 36 that support the rotor shafts 33 and 34 of the screw rotors 31 and 32, respectively. The communication hole 53 formed in the lower part of the partition wall 54 communicates the bottom part of the rotor chamber 47 and the liquid reservoir 52 formed in the lower part of the gear chamber 51. The communication hole 53 functions as a flow path for introducing the oil accumulated in the liquid reservoir 52 of the gear device 50 into the rotor chamber 47. The opening of the communication hole 53 in the gear chamber 51 is disposed at such a height that the lower end 59 a of the gear mechanism 59 is not immersed in the oil accumulated in the liquid reservoir 52. In other words, the gear chamber 51 is configured so that the lower end portion of the gear mechanism 59 is positioned higher than the communication hole 53. Further, the gear chamber 51 is configured so that the lower end 59 a of the gear mechanism 59 is positioned higher than the lower ends of the screw rotors 31 and 32.

  In the discharge-side housing 30 b, a pair of insertion holes 41 for inserting the respective rotor shafts 33 and 34 of the male and female screw rotors adjacent to the rotor chamber 47, and downstream of the respective insertion holes 41, are provided. A bearing space 44 for forming a pair of discharge-side bearing portions 37 that support the rotor shafts 33 and 34 is formed.

  A discharge-side shaft sealing portion 38 is provided so as to be adjacent to the rotor chamber 47 corresponding to the discharge-side rotor shafts 33 and 34. An oil supply hole 42 is formed in the side wall of the discharge side housing 30b to connect the oil supply flow path 22 and the discharge side shaft seal portion 38 on the male screw rotor side (hereinafter referred to as the male side). An oil supply communication hole 43 is formed in a central partition formed between the pair of insertion holes 41 of the discharge side housing 30b. The oil supply communication hole 43 is formed on the male discharge side shaft seal portion 38 and the female screw rotor side. The discharge side shaft sealing portion 38 (hereinafter referred to as a female side) is connected.

  The pair of insertion holes 41 are cylindrical through holes extending in the axial direction of the rotor shafts 33 and 34 on the male side and the female side, and are sized and configured to be slightly larger in diameter than the rotor shafts 33 and 34. ing. A male discharge-side shaft sealing portion 38 is formed by a gap formed between the inner wall surface of the male insertion hole 41 and the outer peripheral surface of the male rotor shaft 33. Similarly, a female-side discharge-side shaft sealing portion 38 is formed by a gap formed between the inner wall surface of the female-side insertion hole 41 and the outer peripheral surface of the female-side rotor shaft 33. The shaft seal functions by applying a predetermined pressure to the discharge side shaft seal portion 38. Therefore, the discharge-side oil supply flow path 40 may be configured to be supplied with oil having a substantially discharge pressure P <b> 1 ′ that can cause a shaft seal action to the discharge-side shaft seal portion 38.

  At the boundary between the rotor chamber housing 30a and the discharge side housing 30b, compressed gas having a discharge pressure P1 exists on the discharge side of the rotor chamber 47, and oil having a substantially discharge pressure P1 ′ is supplied on the discharge side shaft seal portion 38 side. ing. As a result, there is almost no pressure difference between the rotor chamber 47 and the discharge-side shaft sealing portion 38, and the pressures are substantially balanced. As a result, since the flow of oil in the discharge side shaft seal portion 38 is restricted, the discharge side shaft seal portion 38 has a sealing action that prevents leakage of compressed gas from the discharge side of the rotor chamber 47, and the shaft Acts as a seal. In addition, in order to enhance oil filling properties in the gaps between the insertion hole 41 and the rotor shafts 33 and 34 to prevent oil from running out, the discharge side shaft sealing portion 38 has an oil supply hole 42 and an oil supply communication hole 43. At a portion corresponding to the position, at least one annular groove 36 is provided. In this embodiment, since the groove processing is easy, an annular groove 36 is formed on the outer peripheral surface of the rotor shafts 33, 34 corresponding to the discharge side shaft sealing portion 38, but the inner periphery of the insertion hole 41 It may be formed in the surface, and may be formed in both the inner peripheral surface and the outer peripheral surface.

  The bearing space 44 has a configuration in which two cylindrical spaces having a diameter larger than that of the insertion hole 41 are arranged in parallel in the direction perpendicular to the axis, and a discharge side bearing portion 37 on the male side and the female side is provided in each cylindrical space. Each is attached. Each of the discharge-side bearing portions 37 through which the rotor shafts 33 and 34 are inserted is attached to the upstream portion of the bearing space 44. The space formed in the downstream portion of the bearing space 44 is in an airtight state. A discharge-side bearing recess 45 connected to the discharge-side shaft sealing portion 38 is formed in a portion facing the discharge-side bearing portion 37 in the discharge-side housing 30b and in an outer peripheral portion of the insertion hole 41. Accordingly, the discharge-side bearing recess 45 can guide oil present in the discharge-side shaft seal portion 38 to the discharge-side bearing portion 37. The discharge-side bearing recess 45 is formed by an annular gap that is recessed so as to increase in diameter from the insertion hole 41. In this embodiment, the discharge-side bearing recess 45 has an annular shape that is larger in diameter than the insertion hole 41 and recessed in a step shape. It is composed of gaps.

  According to the above configuration, the oil supply hole 42 (the oil supply communication hole 43 on the female side), the discharge side shaft sealing portion 38 and the discharge side bearing recess 45 supplies the discharge side bearing portion 37 with oil on the discharge side oil supply passage. 40 is formed. In the discharge-side oil supply flow path 40, when oil having a substantially discharge pressure P1 ′ is supplied to the oil supply hole 42 through the oil supply flow path 22, the discharge-side shaft seal portion 38 is filled with oil having a substantially discharge pressure P1 ′. The discharge side shaft sealing portion 38 exhibits a shaft sealing action. Process in which oil having substantially discharge pressure P1 ′ in the discharge side shaft seal portion 38 is guided to the bearing space 44 slightly lower than the discharge side shaft seal portion 38 through the discharge side bearing recess 45 and the discharge side bearing portion 37. Thus, the discharge-side bearing portion 37 is lubricated. The pressure P2 of the oil led to the bearing space 44 by lubricating the discharge side bearing portion 37 is slightly lower than the discharge pressure P1 ′, but has a pressure sufficiently higher than the atmospheric pressure. . That is, the bearing space 44 passes through the discharge-side shaft seal portion 38 and the discharge-side bearing portion 37 and is oil having a pressure P2 slightly lower than the discharge pressure P1 ′ (hereinafter referred to as discharge-side shaft seal / bearing oil). ). The bearing space 44 and the gear chamber 51 communicate with each other through the gear chamber oil supply passage 60, and the discharge-side shaft seal / bearing oil that exists in the bearing space 44 passes through the gear chamber oil supply passage 60 to the gear chamber 51. Led.

  Since the discharge-side shaft seal portion 38 is adjacent to the discharge-side rotor chamber 47 that confines the compressed gas having the maximum discharge pressure P1 in the oil-cooled screw compressor 1, the discharge existing on the discharge side of the rotor chamber 47 The oil in which the compressed gas having the pressure P1 is dissolved in the form of minute bubbles leaks to the discharge side shaft seal portion 38 and is supplied to the discharge side shaft seal portion 38 through the oil supply passage 22. It is thought that mixing occurs. Since all of the discharge side oil supply passage 40, the bearing space 44, and the gear chamber oil supply passage 60 are in an airtight state, the oil at the substantially discharge pressure P1 ′ at the discharge side shaft seal portion 38 and the pressure P2 at the bearing space 44 are reduced. The discharge side shaft seal and bearing oil both maintain the state where the compressed gas is dissolved in the oil. Therefore, the discharge side shaft seal / bearing oil at the pressure P2 in the gear chamber oil supply passage 60 contains compressed gas dissolved in the form of minute bubbles.

  The gear chamber oil supply passage 60 is provided with an orifice 62 as a pressure holding portion. The office 62 is provided to keep the pressure of the discharge side shaft seal / bearing oil at the pressure P2 and to prevent the compressed gas from expanding before being introduced into the gear chamber 51. Therefore, if the orifice 62 is only for the purpose of suppressing the expansion of the compressed gas, the orifice 62 may be disposed at any position in the middle of the gear chamber oil supply passage 60. Note that the more the orifice 62 is arranged in the vicinity of the gear chamber 51, the more the oil jet power can be maintained and the more effective the oil can be supplied to the gear mechanism 59, so the orifice 62 is arranged immediately before the gear chamber 51. Desirably, in this case, the orifice 62 may be configured to function as an oil injection nozzle serving as an oil injection port. Moreover, you may use the commercially available fluid nozzle of a suitable aperture | diameter as a pressure holding part.

  An oil filling port (not shown) is provided in the upper part of the gear chamber 51, and the gear chamber oil supply passage 60 is connected thereto. Through the oil supply port of the gear chamber 51, the discharge side shaft seal / bearing oil from the gear chamber oil supply passage 60 is supplied to the gear mechanism 59 inside the gear chamber 51. Since the discharge-side shaft seal / bearing oil from the gear chamber oil supply passage 60 has a high pressure P2, the discharge-side shaft seal / bearing oil is contained in the discharge-side shaft seal / bearing oil as soon as it is guided to the gear chamber 51. The compressed gas expands at once. The discharge-side shaft seal / bearing oil guided to the gear chamber 51 ejects vigorously toward the gear mechanism 59 to lubricate the driven gear 57 and the drive gear 58 of the gear mechanism 59. The oil that has lubricated the gear mechanism 59 flows down and accumulates in the liquid reservoir 52 of the gear device 50. During the oil supply process to the gear mechanism 59, the gear chamber 51 is in a pressurized state in which the internal pressure is higher than the atmospheric pressure due to the pressure from the compressed gas that is contained in the discharge side shaft seal / bearing oil and expands at once.

  Since the internal pressure of the gear chamber 51 is higher than the atmospheric pressure, the oil level 55 of the liquid reservoir 52 is pushed down, and the oil accumulated in the liquid reservoir 52 of the gear device 50 is communicated with the communication hole 53. Through the rotor chamber 47 and discharged. Accordingly, the lower end portion 59a of the gear mechanism 59 is not immersed in the oil surface 55 of the oil accumulated in the liquid reservoir 52 when the compressor body 2 is operated.

  Accordingly, the oil accumulated in the liquid reservoir 52 of the gear chamber 51 is discharged to the rotor chamber 47 through the communication hole 53 when the compressor body 2 is operated, so that more oil than necessary is accumulated in the gear chamber 51. As a result, a reduction in energy loss due to stirring and a suppression of an increase in oil temperature can be realized.

  In the gear chamber 51 configured such that the lower end portion of the gear mechanism 59 is higher than the lower end portions of the communication hole 53 and the screw rotors 31 and 32, the gear chamber is provided even when the compressor body 2 is stopped. The oil level in 51 does not greatly exceed the height of the lower ends of the screw rotors 31 and 32. Since it is possible to prevent excessive oil from accumulating in the gear chamber 51 even when the compressor body 2 is stopped, it is possible to reduce energy loss due to agitation and to suppress oil temperature rise during restart. It is possible to prevent power loss during operation more reliably.

  Further, the lower end portion of the gear mechanism 59 is configured to be higher than the communication hole 53 and the lower end portions of the screw rotors 31 and 32, and the upper end portion of the communication hole 53 is the lower end portion of the screw rotors 31 and 32. In the gear chamber 51 configured to be at a higher position, the oil level in the gear chamber 51 is likely to be lowered to the communication hole. Therefore, the compressed gas generated by expanding in the gear chamber 51 can be quickly sent to the suction side of the rotor chamber 47 without staying more than necessary, and the compressed gas generated in the gear chamber 51 is wasted. There is nothing.

  Next, the overall package configuration of the oil-cooled screw compressor 1 will be described with reference to FIG.

  This package-type oil-cooled screw compressor 1 includes a compressor body 2, a motor 3 that drives the compressor body 2, an oil separation / recovery unit 6 that separates and recovers oil from compressed gas, and an oil separation / recovery unit 6. An oil cooler 8 that cools the oil separated and recovered in step 1, an aftercooler 16 that cools the compressed gas from which the oil is separated by the oil separation and recovery device 6, a sirocco fan 18 for air-cooling the oil cooler 8 and the aftercooler 16, and It has various piping systems.

  The compressor main body 2 driven by the motor 3 is provided with a suction filter and an intake control valve on the suction side, and an oil separator / collector 6 on the discharge side. An oil separation element 6 a is provided at the upper part of the oil separation and recovery unit 6, and an oil separator tank 6 b is attached to the lower part of the oil separation and recovery unit 6. The discharge side of the compressor body 2 and the oil separator / collector 6 are connected by a gas discharge passage 13. Furthermore, the gas discharge flow path 13 connected to the oil separation element 6 a side of the oil separation and recovery device 6 includes an air release device, a safety valve, and a pressure holding check valve, and reaches the aftercooler 16. Further, when the oil collected in the oil reservoir 6c of the oil separator tank 6b is higher than the set value, the oil passes through the oil filter, the automatic temperature control valve and the oil cooler 8, or when the oil temperature is lower than the set value. Is provided with an oil supply passage 22 configured to reach the compressor main body 2 through the bypass passage without passing through the oil cooler 8 from the automatic temperature control valve.

  The compressor main body 2 compresses the gas sucked through the suction filter and the intake control valve while receiving oil from the oil supply passage 22, and compresses the compressed gas containing oil into the gas discharge passage 13 at the discharge pressure P <b> 1. Discharge and reach the oil separator / collector 6. Since the gas discharge flow path 13 on the downstream side of the oil separation element 6a of the oil separation / recovery unit 6 includes a pressure holding check valve, the pressure inside the oil separation / recovery unit 6 can be maintained. Gas-liquid separation is performed in the process in which the compressed gas passes through the oil separation element 6a of the oil separation / recovery unit 6. The compressed gas is sent to a compressed gas demand facility 17 outside the machine through a gas discharge passage 13 including an after cooler 16, a drain separator and a ball valve. The oil separated and collected by the oil separator / collector 6 in the pressure-retained state and stored in the oil separator tank 6b is sent to the oil supply flow path 22 with the gas pressure maintained without being pressurized by the oil pump. Then, the oil is supplied to the discharge side shaft sealing portion 38 (shown in FIG. 1 and the like) of the compressor main body 2 and the compression side space of the rotor chamber 47 (shown in FIG. 1 and the like) through the oil supply passage 22.

  Oil containing a large amount of fine bubbles is stored in the oil reservoir 6c of the oil separator tank 6b of the oil separator / collector 6 in a state where the pressure is substantially maintained at the discharge pressure. For this reason, by using this oil, it is possible to stably secure an oil having a substantially discharge pressure containing a large amount of fine bubbles. Further, the oil in the oil sump 6c of the oil separator / collector 6 maintained at a substantially discharge pressure is supplied to the discharge-side shaft seal portion 38 using the retained gas pressure, whereby the discharge-side oil supply means is provided. There is no need to provide it separately, and the cost can be reduced. Since the other points are the same as those of the embodiment shown in FIGS. 1 to 3 described above, description thereof will be omitted.

1: Package type oil-cooled screw compressor 2: Compressor body 3: Motor 4: Suction port 5: Discharge port 6: Oil separator / collector 8: Oil cooler 13: Gas discharge flow path 18: Cooling fan 22: Oil supply flow path 30: Casing 30a: Rotor chamber housing 30b: Discharge side housing 31: Male screw rotor 32: Female screw rotor 33: Rotor shaft 34: Rotor shaft 35: Output shaft 36: Groove 37: Discharge side bearing portion 38: Discharge side shaft seal portion 39: Rotor meshing portion 40: Discharge side oil supply passage 41: Insertion hole 42: Oil supply hole 43: Oil supply communication hole 44: Bearing space 45: Discharge side bearing recess 46: Suction chamber 47: Rotor chamber 50: Gear device 51: Gear chamber 52: Liquid reservoir 53: Communication hole 54: Partition wall 55: Oil surface 59: Gear mechanism 60: Gear chamber oil supply flow path 62: Orifice (pressure retaining portion)

Claims (7)

An oil-cooled screw compressor in which a pair of male and female screw rotors that rotate in a meshing state and compress compressed gas is housed in a rotor chamber of a casing, the oil-cooled screw compressor is
A gear chamber that houses a gear mechanism that transmits a rotational driving force from a driving source to any one of the pair of screw rotors in an airtight state, and the gear chamber is located on the suction side of the casing. The rotor chamber and the liquid reservoir portion of the gear chamber communicate with each other through a communication hole formed in the partition, and the lower end portion of the gear mechanism is connected to the chamber through the communication hole. A gear chamber configured at a higher position,
After supplying approximately discharge pressure of oil to the discharge-side shaft seal portion corresponding to the rotor shaft on the discharge side of the pair of screw rotors, the oil flowing out from the discharge-side shaft seal portion is supplied to the discharge-side bearing portion. A discharge-side oil supply flow path,
An oil-cooled screw compressor, comprising: a gear chamber oil supply passage for supplying discharge-side shaft seal / bearing oil that has flowed out of the discharge-side bearing portion to the gear mechanism of the gear chamber.   The oil at the substantially discharge pressure in the discharge side shaft seal is introduced in a state where the discharge gas discharged from the rotor chamber is held by a holding pressure check valve and separated and recovered. The oil-cooled screw compressor according to claim 1, wherein the oil-cooled screw compressor is supplied from a reservoir.   3. The oil according to claim 2, wherein the oil at the substantially discharge pressure in the discharge side shaft seal portion is supplied from the oil reservoir at a gas pressure held in the oil separation and recovery device. Cold screw compressor.   The oil-cooled screw compressor according to any one of claims 1 to 3, wherein a pressure holding portion is provided in the gear chamber oil supply passage.   The oil-cooled screw compressor according to claim 4, wherein the pressure holding portion is provided immediately before the gear chamber.   The oil-cooled screw according to any one of claims 1 to 5, wherein the gear chamber is configured such that a lower end portion of the gear mechanism is higher than a lower end portion of the screw rotor. Compressor.   The oil-cooled screw compressor according to claim 6, wherein an upper end portion of the communication hole is configured to be higher than a lower end portion of the screw rotor.

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