JP4981557B2 - Turbo compressor and turbo refrigerator - Google Patents

Description

  The present invention relates to a turbo compressor that improves a cooling mechanism of a bearing that supports a rotating shaft on which an impeller is provided, and can be further increased in speed and size, and a turbo refrigerator using the turbo compressor.

  In a turbo compressor applied to a turbo refrigerator, there is still a high need for cost reduction by downsizing the compressor itself as well as high performance. In order to reduce the size of the turbo compressor, it is necessary to rotate the impeller at a higher speed. For this purpose, it is indispensable to improve the bearing that supports the rotating shaft provided with the impeller. In turbo compressors, sliding bearings that support and support the shaft with an oil film and rolling bearings that use rolling balls or rollers are used as bearings that support the rotating shaft. This increases the mechanical loss of the chiller, causing a problem of reducing the performance of the refrigerator.

  In general, in a rotating shaft system, a sliding bearing is used for a high load, and a rolling bearing is used for a medium to low load. However, if the shaft support rigidity and load conditions can be within an allowable range, a sliding bearing can be used. However, it is preferable to use a rolling bearing with a small mechanical loss. Even in a turbo compressor, a rolling bearing with a smaller mechanical loss is used as a bearing for a rotating shaft provided with an impeller for speeding up. (For example, refer to Patent Document 1).

  Also, under high-speed rotation and high load conditions, cooling and lubrication of the bearing that supports the rotating shaft is inevitable. The lubricating oil supplied to the bearing has two functions: a lubricating function that forms and secures an oil film between the ball or roller of the bearing and the inner and outer rings, and a cooling function that removes generated heat by the oil. . Patent Document 1 discloses a configuration in which lubricating oil or liquid refrigerant is supplied into a bearing box in which a rolling bearing is provided, and the rolling bearing is lubricated and cooled with oil or refrigerant. Patent Document 2 discloses a liquid refrigerant extracted from a condenser outlet of a refrigeration cycle and introduced into a turbo compressor to cool a bearing and a drive motor.

Japanese Patent Application Laid-Open No. 2000-291587 JP 2006-194579 A

  In a turbo compressor that rotates an impeller at high speed via a rotating shaft, the cooling and lubrication of the bearing is the point of speeding up. Various ideas have been made. On the other hand, the mechanical loss of the bearing includes a loss due to rolling of balls and rollers and a loss due to stirring of the lubricating oil. To reduce the stirring loss, the application of jet lubrication, mist lubrication, etc. It is necessary to keep the amount of oil supply to a minimum. However, if the amount of oil is simply reduced, the generated heat cannot be sufficiently removed by the lubricating oil, so the bearing temperature rises and the oil film breaks due to a local decrease in the viscosity of the oil. It may cause a metal touch with the inner ring or the outer ring, resulting in damage such as flaking.

  In the above two functions of the lubricating oil supplied to the bearing, the relationship between the minimum lubricating oil amount A for securing an oil film and the minimum lubricating oil amount B for cooling is generally A << B. In order to reduce the amount of oil used and reduce the stirring loss, it is necessary to cool the bearing by another means. Patent Documents 1 and 2 disclose cooling and lubricating a bearing using a refrigerant extracted from a refrigeration cycle. However, these merely show that the bearing is cooled and lubricated by the refrigerant, and does not disclose a configuration for reducing the mechanical loss including the stirring loss of the cooling medium in the bearing. Therefore, with such a cooling and lubrication configuration, the mechanical loss of the bearing cannot be sufficiently reduced, and it is difficult to further increase the speed and size of the turbo compressor.

  The present invention has been made in view of such circumstances, and further increases the speed by improving the cooling mechanism of the bearing that supports the rotating shaft provided with the impeller and reducing the mechanical loss of the bearing. An object of the present invention is to provide a turbo compressor and a turbo refrigerator that can be miniaturized.

In order to solve the above problems, the turbo compressor and the turbo refrigerator of the present invention employ the following means.
That is, a turbo compressor according to the present invention is a turbo compressor that is rotatably supported by a housing via a bearing and is provided with an impeller at least at one end of a rotating shaft that is rotated by a driving source. The rotary shaft cooling mechanism for cooling at least the vicinity of the support portion of the rotary shaft by the bearing is provided inside the shaft using the refrigerant extracted from the refrigeration cycle of the turbo refrigerator as a cooling medium.

In turbo compressors, in addition to high performance, there is a great need for higher speed and smaller size. In order to increase the speed and size of the turbo compressor, one problem is to reduce the mechanical loss in the rotating shaft system that drives the impeller. Therefore, a rolling bearing with relatively little mechanical loss is used for the bearing that supports the rotating shaft. However, it is not sufficient to reduce the mechanical loss simply by changing the bearing to a rolling bearing, and the agitation loss generated by agitating the lubricating oil supplied to the bearing cannot be ignored. To reduce the agitation loss of the lubricating oil, it is sufficient to reduce the amount of oil supply. However, simply reducing the oil supply amount makes it impossible to remove the heat generated during high-speed rotation and increases the bearing temperature, resulting in a decrease in the viscosity of the lubricating oil. Occurrence of oil film breakage may cause damage due to poor lubrication.
According to the present invention, the bearing can be cooled from the inner ring side via the rotating shaft cooled from the inside of the shaft by the rotating shaft cooling mechanism using the refrigerant extracted from the refrigeration cycle as the cooling medium. In this way, by cooling the bearing from the rotating shaft side, it is not necessary to supply a large amount of lubricating oil to the bearing to remove heat, and the amount of oil supplied to the bearing can be suppressed to the minimum amount of oil necessary for lubrication. Thereby, the stirring loss of the lubricating oil in the bearing can be reduced. In addition, since the bearing is cooled from the inner ring side, it is possible to cool the inner ring against the temperature of the ball or roller that has the highest temperature inside the bearing and keep the temperature low, and ideally maintain the clearance inside the bearing. be able to. Thereby, the thermal expansion of a bearing can be suppressed, the load concerning a ball | bowl and a roller can be reduced, and a mechanical loss can be reduced. Therefore, the turbo compressor can be further increased in speed and reduced in size, and cost reduction and downsizing and high performance can be realized.

  Furthermore, the turbo compressor of the present invention is the above-described turbo compressor, wherein the rotary shaft cooling mechanism includes a refrigerant passage that is drilled along the axial direction in the axial center of the rotary shaft and through which the refrigerant flows. It is characterized by that.

  According to the present invention, the refrigerant is circulated through the refrigerant passage formed along the axial direction in the axial center of the rotating shaft, and the rotating shaft is cooled by absorbing heat from the shaft side and evaporating the refrigerant. Thus, the bearing can be cooled from the inner ring side. Therefore, the rotating shaft cooling mechanism efficiently cools the rotating shaft and the bearing by using the phase change of the refrigerant, and the mechanical loss due to the load generated by the thermal expansion of the bearing can be reduced. The amount can be reduced to the minimum amount of lubricating oil required for lubrication.

  Furthermore, the turbo compressor of the present invention is the above turbo compressor, wherein the refrigerant passage is provided to penetrate from one end side to the other end side of the rotating shaft, and the refrigerant evaporated in the refrigerant passage is, The rotary shaft flows out from the impeller side end of the rotary shaft into the refrigerant suction passage of the compressor.

  According to the present invention, since the refrigerant passage is provided penetrating from one end side to the other end side of the rotating shaft, the refrigerant shaft is led from the refrigeration cycle to the rotating shaft cooling mechanism and is evaporated while flowing in the refrigerant passage. The refrigerant that has been cooled can be directly discharged from the end of the rotating shaft on the impeller side to the refrigerant suction passage of the compressor. Therefore, it is possible to simply configure the rotating shaft cooling mechanism, the refrigerant flow path, and the rotating shaft.

  Furthermore, the turbo compressor of the present invention is the turbo compressor described above, wherein the refrigerant passage is drilled from one end side to the other end side of the rotating shaft and before the position where the impeller is provided. The refrigerant that is communicated with the oil exhaust space in the housing and evaporated in the refrigerant passage flows out into the oil exhaust space, and then is guided to the refrigerant suction passage of the compressor through the pressure equalizing passage. Features.

  According to the present invention, the refrigerant passage is drilled from one end side to the other end side of the rotating shaft and communicates with the oil drain space in the housing before the position where the impeller is provided. The refrigerant, which has been led to the rotating shaft cooling mechanism and evaporated while flowing in the refrigerant passage to cool the rotating shaft, flows out into the oil drain space in the housing, and then sucks the refrigerant in the compressor through the pressure equalizing passage. It can be led to the flow path. Therefore, even when the refrigerant does not evaporate completely in the refrigerant passage, the liquid component can be separated in the oil discharge space, and only the gas refrigerant can be guided to the refrigerant suction passage of the compressor. Can be prevented.

  Furthermore, in any one of the above-described turbo compressors, the turbo compressor of the present invention is provided with a fixed throttle for reducing the refrigerant introduced from the refrigeration cycle to a low-temperature low-pressure refrigerant at the inlet of the refrigerant passage, The refrigerant depressurized by a fixed throttle is introduced into the refrigerant passage.

  According to the present invention, the fixed throttle is provided at the inlet of the refrigerant passage, and the refrigerant guided from the refrigeration cycle is reliably reduced in pressure to the low-temperature and low-pressure refrigerant by the fixed throttle and introduced into the refrigerant passage. For this reason, the refrigerant introduced into the refrigerant passage immediately absorbs heat from the shaft side and evaporates to cool the rotating shaft. Therefore, the rotating shaft can be efficiently cooled by the latent heat of vaporization of the refrigerant, and the bearing can be efficiently cooled from the inner ring side via the rotating shaft.

  Furthermore, in the turbo compressor according to the present invention, in any one of the above-described turbo compressors, the rotary shaft cooling mechanism includes a refrigerant introduction system that guides the refrigerant extracted from the refrigeration cycle to the refrigerant passage of the rotary shaft. The refrigerant introduction system path is provided with a flow rate adjusting valve for adjusting the flow rate of the refrigerant.

  According to the present invention, the flow rate adjusting valve for adjusting the flow rate of the refrigerant is provided in the refrigerant introduction system path that guides the refrigerant extracted from the refrigeration cycle to the refrigerant passage of the rotation shaft. The flow rate adjustment valve can be adjusted appropriately according to the operating conditions. Therefore, an appropriate amount of refrigerant can always be introduced into the refrigerant passage of the rotating shaft, and a stable cooling effect can be obtained.

  Further, in the turbo compressor according to the present invention, in the above turbo compressor, the flow rate control valve causes the refrigerant evaporated by cooling the rotating shaft to be returned to the refrigerant suction passage of the compressor, and then to the compressor. The refrigerant temperature in the vicinity where it merges with the suction refrigerant is controlled to be equal to or higher than the pressure saturation temperature.

  According to the present invention, the flow rate control valve provided in the refrigerant introduction system is configured so that the refrigerant used for cooling the rotating shaft is returned to the refrigerant suction passage of the compressor, and the refrigerant temperature in the vicinity where the refrigerant merges with the suction refrigerant is pressurized. Since the temperature is controlled to be equal to or higher than the saturation temperature, the flow rate of the refrigerant introduced into the rotating shaft cooling mechanism can be adjusted to an appropriate amount that does not cause liquid return. Therefore, the maximum cooling capacity of the rotating shaft cooling mechanism capable of reliably preventing liquid compression is enabled, and the rotating shaft and the bearing can be efficiently cooled.

  Furthermore, the turbo compressor of the present invention is the turbo compressor according to any one of the above-described turbo compressors, wherein the rotating shaft cooling mechanism is attached to the refrigerant passage inlet of the rotating shaft, and the fixed throttle that rotates together with the rotating shaft. And a seal member that seals the outer peripheral surface of the nozzle as a seal surface and that does not contact the refrigerant introduction path.

  According to the present invention, a nozzle having a fixed throttle that rotates together with the rotation shaft is attached to the refrigerant passage inlet portion of the rotation shaft, the outer peripheral surface of the nozzle is used as a seal surface, and the seal that seals non-contact with the refrigerant introduction system path Since the member is provided, it is possible to seal between the stationary-side refrigerant introduction system path and the rotating refrigerant path without adding extra resistance to the rotating shaft. Therefore, the refrigerant can be reliably guided into the refrigerant passage of the rotating shaft without causing power loss.

  Furthermore, the turbo compressor of the present invention is the above-described turbo compressor, wherein the bearing is installed in the housing via a bearing box, and the bearing box has a bearing box cooling mechanism for cooling the bearing. Is provided.

  According to the present invention, the bearing that supports the rotating shaft is installed in the housing via the bearing box, and the bearing box cooling mechanism that cools the bearing is provided in the bearing box. Cooling can also be performed from the outer ring side by the cooling mechanism. Thereby, the cooling effect of the bearing can be further enhanced, the amount of oil supplied to the bearing can be made the minimum amount of lubricating oil, and the temperature difference between the inner and outer rings of the bearing can be made as small as possible. Therefore, the mechanical loss of the bearing can be further reduced.

  Furthermore, the turbo compressor of the present invention is characterized in that, in the above turbo compressor, the bearing box cooling mechanism uses a refrigerant extracted from a refrigerating cycle of the turbo refrigerator or a cooling oil for lubrication as a cooling medium. To do.

  According to the present invention, the bearing box is cooled by the bearing box cooling mechanism using the refrigerant extracted from the refrigeration cycle of the centrifugal chiller or the cooling oil used for lubrication as a cooling medium, and the bearing is also cooled from the outer ring side through the bearing box. It can be cooled efficiently. Accordingly, the cooling effect of the bearing can be further enhanced, the amount of oil supplied to the bearing can be made the minimum amount of lubricating oil, and the temperature difference between the inner and outer rings of the bearing can be made as small as possible.

  Furthermore, the turbo compressor of the present invention is characterized in that, in any of the above turbo compressors, the refrigerant is extracted from a reservoir of a condenser constituting the refrigeration cycle.

  According to the present invention, since the refrigerant used for the cooling medium is extracted from the liquid reservoir of the condenser constituting the refrigeration cycle, the liquid refrigerant is discharged from the liquid reservoir of the condenser using the condensation pressure that is a high pressure in the refrigeration cycle. Can be introduced directly into the cooling mechanism. Thereby, the condensed liquid refrigerant can be taken out from the system of the turbo refrigerator itself and can be effectively used for cooling the bearing.

  Furthermore, the turbo compressor of the present invention is characterized in that, in any of the above-described turbo compressors, the refrigerant is extracted from an outlet of a liquid refrigerant cooling subcooler constituting the refrigeration cycle.

  According to the present invention, since the refrigerant used for the cooling medium is extracted from the outlet of the liquid refrigerant cooling subcooler constituting the refrigeration cycle, the subcooler outlet pressure corresponding to the condensation pressure, which is the high pressure in the refrigeration cycle, is used. The liquid refrigerant supercooled from the outlet of the subcooler can be directly introduced into the cooling mechanism. As a result, the supercooled liquid refrigerant can be taken out from the system of the turbo refrigerator itself and can be effectively used for cooling the bearing.

  Furthermore, the turbo compressor of the present invention is characterized in that, in any of the above turbo compressors, the refrigerant is extracted from an outlet of an economizer constituting the refrigeration cycle.

  According to the present invention, since the refrigerant used for the cooling medium is extracted from the outlet of the economizer constituting the refrigeration cycle, the condensing pressure that is the high pressure in the refrigeration cycle or the intermediate pressure between the high pressure and the low pressure is used. The liquid refrigerant supercooled from the outlet of the economizer can be directly introduced into the cooling mechanism. As a result, the supercooled liquid refrigerant can be taken out from the system of the turbo refrigerator itself and can be effectively used for cooling the bearing. The economizer cycle includes an intercooler system and a gas-liquid separator system, and the intercooler system is particularly used for turbo chillers that use a mixed refrigerant whose refrigerant composition changes due to self-expansion. Is preferred.

  Furthermore, the turbo compressor according to the present invention is the turbo compressor according to any one of the above-described turbo compressors, wherein the refrigerant is supplied from a refrigerant liquid reservoir of an evaporator constituting the refrigeration cycle via a pump or an eductor using a high-pressure refrigerant gas as a drive source. Extracted.

  According to the present invention, the refrigerant used for the cooling medium is extracted from the refrigerant liquid reservoir of the evaporator constituting the refrigeration cycle through the pump or the eductor driven by the high-pressure refrigerant gas. A low-temperature and low-pressure liquid refrigerant can be pumped through a pump or an eductor and introduced into the cooling mechanism. As a result, the low-temperature and low-pressure liquid refrigerant can be taken out of the turbo refrigerator itself and can be effectively used for cooling the bearing.

  Furthermore, the turbo refrigerator according to the present invention includes any one of the above-described turbo compressors as a turbo compressor constituting the refrigeration cycle.

  According to the present invention, a refrigeration cycle can be configured using a high-performance turbo compressor that has been speeded up and miniaturized as described above as a turbo compressor. Therefore, a small-sized, high-performance and low-cost turbo chiller can be provided.

According to the turbo compressor of the present invention, since the bearing can be cooled from the inner ring side via the rotating shaft cooled by the rotating shaft cooling mechanism, it is not necessary to supply a large amount of lubricating oil to the bearing and remove the heat. The amount of oil supplied to the bearing can be suppressed to the minimum amount of oil necessary for lubrication. Thereby, the stirring loss of the lubricating oil in the bearing can be reduced. In addition, since the bearing is cooled from the inner ring side, it is possible to cool the inner ring against the temperature of the ball or roller that has the highest temperature inside the bearing and keep the temperature low, and ideally maintain the clearance inside the bearing. be able to. Thereby, the thermal expansion of a bearing can be suppressed, the load concerning a ball | bowl and a roller can be reduced, and a mechanical loss can be reduced. Therefore, the turbo compressor can be further increased in speed and reduced in size, and cost reduction and downsizing and high performance can be realized.
In addition, according to the turbo chiller of the present invention, a refrigeration cycle can be configured using a high-performance turbo compressor that is speeded up and downsized, and thus a small-sized high-performance and low-cost turbo chiller is provided. can do.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a longitudinal sectional view of a turbo compressor 1 according to the first embodiment of the present invention. The turbo compressor 1 includes a housing 2 configured by integrally connecting a compressor side housing 2A and a motor side housing 2B. An electric motor 3 that is driven at a variable speed via an inverter device (not shown) is incorporated in the motor-side housing 2B. One end of the motor shaft 3A of the electric motor 3 projects from the motor side housing 2B to the compressor side housing 2A.

  A refrigerant gas suction port 5 having a variable guide vane 4 is formed in the compressor-side housing 2A, and a first-stage compression stage 6 and a second-stage compression are provided in a downstream flow path following the suction port 5. Stages 7 are sequentially provided. The first stage compression stage 6 is provided with a diffuser part 8, a return vent 9 and a guide vane 10, and the second stage compression stage 7 is provided with a diffuser part 11 and a scroll chamber 12. The compressed refrigerant gas is discharged from the scroll chamber 12 through a discharge port (not shown).

  In addition, a rotary shaft 13 is rotatably installed in the compressor-side housing 2A, and a first stage impeller 14 for the first stage compression stage 6 and a second stage are provided on one end side of the rotary shaft 13. A second stage impeller 15 for the compression stage 7 is provided. The rotary shaft 13 is supported by a rolling bearing 17 consisting of a plurality of angular ball bearings, the central portion of which is installed in the compressor-side housing 2A via a bearing box 16, and the other end is connected to the motor side via a bearing box 18. It is supported by a rolling bearing 19 composed of a plurality of angular ball bearings installed in the housing 2B.

A small-diameter gear 20 is provided at an intermediate portion of the rotary shaft 13 supported by the rolling bearings 17 and 19. The gear 20 is meshed with a large-diameter gear 21 provided at one end of the motor shaft 3A, and a speed increasing mechanism 22 is configured by these gears 20 and 21.
Lubricating oil supply lines 23A and 23B for supplying lubricating oil to the rolling bearings 17 and 19 are connected to the bearing housings 16 and 18, respectively, and are proportional to the rotational speed of the rotary shaft 13 from an oil supply mechanism (not shown). The lubricating oil supply system is configured to supply the minimum amount of lubricating oil required for lubrication supplied to the rolling bearings 17 and 19 from the nozzle holes (not shown) via the bearing boxes 16 and 18. Lubricating oil used for lubricating the rolling bearings 17 and 19 is lubricated to the bearings, and then flows out into the oil drain space 2C in the housing 2 and circulates through the oil drain hole 24 to an oil supply mechanism (not shown). Is done.

In addition, oil grooves 25 and 26 are provided on the outer peripheral portions of the bearing housings 16 and 18, and cooling oil supply lines 27A and 27B for supplying the cooling oil to the oil grooves 25 and 26 are connected to each other. A cooling oil is supplied from an omitted oil supply mechanism through an oil cooler to constitute a bearing box cooling mechanism that cools the outer ring side of each rolling bearing 17, 19 via each bearing box 16, 18. The cooling oil is circulated through an oil drain hole 28 to an oil supply mechanism (not shown).
Furthermore, a through-hole (refrigerant passage) 29 (see FIG. 2) that penetrates from one end to the other end along the axis is provided at the axial center of the rotary shaft 13, and the refrigerant is circulated through the through-hole 29. Thus, the rotating shaft cooling mechanism 30 for cooling the rotating shaft 13 is configured.

  The rotary shaft cooling mechanism 30 is a liquid reservoir in a condenser (specifically, a condenser that constitutes the refrigeration cycle described later) in the refrigeration cycle of the turbo chiller 40 (see FIG. 4) including the turbo compressor 1. A part of the high-pressure liquid refrigerant or the low-pressure liquid refrigerant from the refrigerant piping system or the component equipment from the time until the liquid reservoir in the evaporator is extracted and led to the motor side end of the rotary shaft 13 through the housing 2. A refrigerant introduction system path 31, a flow rate adjusting valve 32 provided in the refrigerant introduction system path 31, and a through hole 29 of the rotary shaft 13, and the refrigerant guided through the refrigerant introduction system path 31 is decompressed by an orifice 33. A labyrinth seal that seals the nozzle 34 that flows into the through-hole 29, and the rotating portion between the nozzle 34 that rotates together with the rotating shaft 13 and the refrigerant introduction system path 31, with the outer peripheral surface of the nozzle 34 as a sealing surface and without contact. a configuration A seal member 35 which consists of the outlet hole 36. to uniformly flow out of the refrigerant which has flowed through the through hole 29 in the circumferential direction from the impeller end to the suction port 5 of the rotary shaft 13.

As shown in FIG. 3 (A), the flow rate adjusting valve 32 is configured so that the refrigerant temperature near the outflow hole 36 of the refrigerant suction port 5 detected by a temperature sensor (Tsuc) 37 provided in the refrigerant suction port 5 is pressure saturated. The refrigerant flow rate is controlled so as to be equal to or higher than the temperature.
Further, as shown in FIG. 3, the outflow hole 36 through which the refrigerant gas flows out from the end portion of the rotating shaft 13 is formed in a circumferential direction from a gap between the end portion of the rotating shaft 13 and the fixed cover 38. The refrigerant gas is configured to be able to uniformly flow out in the circumferential direction through slits 39 provided at equal intervals.

  As shown in FIG. 4, the refrigeration cycle of the turbo chiller 40 includes a turbo compressor 1 that compresses the refrigerant, a condenser 41 that cools and condenses the refrigerant, and a first decompression that depressurizes the high-pressure refrigerant to an intermediate pressure. The valve 42, an economizer 43 that supercools the refrigerant, a second pressure reducing valve 44 that depressurizes the refrigerant to a low pressure state, and an evaporator 45 that evaporates the low pressure refrigerant are connected in a known manner. The refrigerant used as the cooling medium of the rotary shaft cooling mechanism 30 is a refrigerant piping system from the liquid reservoir in the condenser 41 constituting the refrigeration cycle of the turbo refrigerator 40 to the liquid reservoir in the evaporator 45. Alternatively, it can be extracted from any one of the components (A) to (E). Embodiments (A) to (E) will be described below with reference to FIGS.

In the embodiment (A), as shown in FIG. 5, the high-pressure liquid refrigerant condensed in the condenser 41 from the liquid reservoir 41 </ b> A of the condenser 41 is used for the rotary shaft cooling mechanism 30. The refrigerant is extracted into the refrigerant introduction system path 31.
As shown in FIG. 5, the embodiment (B) is supercooled from a subcooler 46 provided downstream of the condenser 41 and further cooling the liquid refrigerant condensed in the condenser 41 to provide supercooling. The extracted refrigerant is extracted into the refrigerant introduction system path 31 of the rotary shaft cooling mechanism 30 using the high pressure.

  In the embodiment (C), as shown in FIG. 6, the refrigerant supercooled in the intermediate cooler 43 </ b> A from the outlet of the economizer (intercooler) 43 </ b> A in an intermediate cooler type cycle called a so-called economizer cycle. Is extracted to the refrigerant introduction system path 31 of the rotary shaft cooling mechanism 30 using the high pressure. The intermediate-pressure gas refrigerant evaporated in the intermediate cooler 43A via the pressure reducing valve 47 is injected between the first compression stage 6 and the second compression stage 7 of the turbo compressor 1 via the refrigerant system 48. The This embodiment is effective in exerting a predetermined capacity in the turbo refrigerator 40 using a mixed refrigerant (for example, R410A refrigerant) whose refrigerant composition changes due to self-expansion.

  In the embodiment (D), as shown in FIG. 7, the supercooling is performed in the gas-liquid separator 43B from the outlet of the economizer (gas-liquid separator) 43B in a gas-liquid separator type cycle called a so-called economizer cycle. The refrigerant thus extracted is extracted to the refrigerant introduction system path 31 of the rotary shaft cooling mechanism 30 using the intermediate pressure. The intermediate-pressure gas refrigerant separated in the gas-liquid separator 43 </ b> B is injected between the first compression stage 6 and the second compression stage 7 of the turbo compressor 1 through the refrigerant system path 49.

  In the embodiment (E), as shown in FIG. 8, the low pressure and low temperature liquid refrigerant decompressed to the low pressure state by the second pressure reducing valve 44 from the liquid reservoir 45A of the evaporator 45 is supplied to the pump 50A or the turbo compressor. The refrigerant introduction system path 31 of the rotary shaft cooling mechanism 30 through the eductor 50B using the high pressure gas refrigerant (R1) extracted from one discharge system path or the high pressure gas refrigerant (R2) extracted from the condenser 41 as a drive source. It is to be extracted.

Next, operations of the turbo compressor 1 and the turbo refrigerator 40 will be described.
When the electric motor 3 is driven and the motor shaft 3 </ b> A is rotated, the rotation is increased by the speed increasing mechanism 22 configured by the gear 21 provided at one end thereof and the gear 20 meshing with the gear 21. Is rotated at high speed. When the rotating shaft 13 is rotated, the first stage impeller 14 and the second stage impeller 15 are rotated, and the compression operation is started. The refrigerant gas sucked into the turbo compressor 1 from the suction port 5 through the variable guide vane 4 by the rotation of the first stage impeller 14 and the second stage impeller 15 is converted into the first stage compression stage 6 and the second stage compression stage. 7 is compressed in two stages. The two-stage compressed high-pressure refrigerant gas is discharged from the scroll chamber 12 to the outside of the compressor through a discharge port (not shown). The high-pressure refrigerant gas circulates in the refrigeration cycle of the turbo refrigerator 40 including the turbo compressor 1 and the condenser 41, the first pressure reducing valve 42, the economizer 43, the second pressure reducing valve 44, the evaporator 45, and the like. Thus, the required refrigeration effect is achieved.

  In the meantime, in the turbo compressor 1, the minimum amount of lubricating oil necessary for lubrication is supplied to the bearing boxes 16 and 18 from the oil supply mechanism side (not shown) through the lubricating oil supply lines 23 </ b> A and 23 </ b> B. Oil is supplied to the rolling bearings 17 and 19 through nozzle holes (not shown). Thereby, each rolling bearing 17 and 19 is lubricated. Similarly, the oil grooves 25 and 26 provided in the outer peripheral portions of the bearing housings 16 and 18 through the cooling oil supply lines 27A and 27B are cooled by the oil cooler from the oil supply mechanism (not shown). It is circulated in. As a result, the outer rings of the rolling bearings 17 and 19 are cooled via the bearing housings 16 and 18.

  On the other hand, a part of the high-pressure liquid refrigerant or the low-pressure liquid refrigerant circulating in the refrigeration cycle of the turbo chiller 40 is extracted from any position (A) to (E) in the refrigeration cycle, and the refrigerant pressure or The refrigerant is introduced into the refrigerant introduction system path 31 of the rotary shaft cooling mechanism 30 using a pump or an ejector. The refrigerant introduced into the rotary shaft cooling mechanism 30 is supplied to the nozzle 34 connected to the rotary shaft 13 via the seal member 35 while the flow rate is adjusted by the flow rate adjusting valve 32 and the pressure is reduced according to the opening degree. Is done. The refrigerant is further decompressed to a low pressure state by an orifice 33 provided in the nozzle 34 and then flows out into the through hole 29 (refrigerant passage) of the rotating shaft 13.

  The refrigerant introduced into the through hole 29 absorbs heat from the rotating shaft 13 rotating at a high speed while flowing through the through hole 29, and cools the rotating shaft 13. As a result, the rolling bearings 17 and 19 that support the rotating shaft 13 are cooled from the inner ring side via the rotating shaft 13, and the heat generation thereof is suppressed. The refrigerant evaporated in the rotating shaft 13 is uniformly discharged in the circumferential direction from the outflow hole 36 provided at the end of the rotating shaft 13 on the impeller side, and merges with the refrigerant gas sucked from the suction port 5 and is compressed again. The At this time, the refrigerant temperature in the vicinity of the outflow hole 36 of the refrigerant suction port 5 is detected by the temperature sensor (Tsuc) 37, and the flow rate adjusting valve 32 controls the refrigerant flow rate so that it becomes equal to or higher than the pressure saturation temperature. As a result, the liquid refrigerant is prevented from flowing out from the outflow hole 36 and sucked into the compressor.

  As described above, the turbo compressor 1 of the present embodiment is configured to transfer a part of the high-pressure liquid refrigerant or the low-pressure liquid refrigerant extracted from any one of the positions (A) to (E) of the refrigeration cycle to the rotary shaft 13. A rotary shaft cooling mechanism that evaporates in the through-hole 29 (refrigerant passage) that is drilled, cools the rotary shaft 13 by the latent heat of evaporation, and cools the rolling bearings 17 and 19 from the inner ring side via the rotary shaft 13. 30. And the rotating shaft cooling mechanism 30 which uses this refrigerant as a cooling medium can be replaced with the bearing cooling mechanism which supplies a cooling medium to a bearing. For this reason, the amount of lubricating oil supplied to the rolling bearings 17 and 19 via the lubricating oil supply lines 23A and 23B can be suppressed to the minimum amount required for lubrication.

Thus, according to the present embodiment, the following operational effects are obtained.
Since the rolling bearings 17 and 19 that support the rotating shaft can be cooled from the rotating shaft 13 side by the rotating shaft cooling mechanism 30, the amount of oil supplied to the rolling bearings 17 and 19 can be suppressed to the minimum oil amount necessary for lubrication. Thereby, the stirring loss of the lubricating oil in the rolling bearings 17 and 19 can be reduced. Further, since the rolling bearings 17 and 19 are cooled from the inner ring side via the rotating shaft 13, the temperature gradient in the bearing is gradually increased from the inner ring side to the outer ring side, and the clearance inside the bearing is ideally maintained. be able to. Thereby, the mechanical loss by the thermal expansion of a bearing can also be reduced. Therefore, the turbo compressor can be further increased in speed and reduced in size, and cost reduction and downsizing and high performance can be realized.

Further, the refrigerant is evaporated in the through hole 29 (refrigerant passage) of the rotating shaft 13, and the rotating shaft 13 and further the rolling bearings 17 and 19 are cooled by the latent heat of vaporization. It can be cooled efficiently. Therefore, it is possible to reduce the mechanical loss caused by the thermal expansion of the rolling bearings 17 and 19, and at the same time, it is possible to suppress the amount of oil supplied to the rolling bearings 17 and 19 to the minimum amount required for lubrication. .
Further, a through hole 29 (refrigerant passage) is provided so as to penetrate from one end side of the rotating shaft 13 to the other end side, and the refrigerant introduced into the through hole 29 and evaporated is used as it is at the end of the rotating shaft 13 on the impeller side. Therefore, the rotary shaft cooling mechanism 30, the refrigerant flow path, and the rotary shaft 13 can be simply configured.

Further, since the refrigerant guided to the rotating shaft 13 side is depressurized by the fixed orifice 33 provided in the nozzle 34, the refrigerant can be surely depressurized to a low temperature and low pressure state and introduced into the through hole 29. Therefore, heat can be immediately absorbed from the shaft side in the through hole 29 to evaporate the refrigerant, the rotating shaft 13 can be efficiently cooled, and the rolling bearings 17 and 19 can be efficiently cooled from the inner ring side via the rotating shaft 13. it can.
In addition, a flow rate adjusting valve 32 for adjusting the flow rate of the refrigerant is provided in the refrigerant introduction system passage 31 that guides the refrigerant extracted from the refrigeration cycle to the through hole (refrigerant passage) 29 of the rotary shaft 13. The refrigerant flow rate is controlled so that the refrigerant temperature in the vicinity where the refrigerant having cooled 13 is returned to the refrigerant suction flow path 5 of the compressor 1 and merged with the refrigerant sucked into the compressor 1 becomes equal to or higher than the pressure saturation temperature. Thus, an appropriate amount of refrigerant can be supplied without causing liquid return to the rotating shaft cooling mechanism 30 side. As a result, the maximum cooling capacity of the rotary shaft cooling mechanism 30 that can reliably prevent liquid compression by the refrigerant returned from the outflow hole 36 to the refrigerant suction flow path 5 is possible, and the rotary shaft 13 and the rolling bearing 17 are efficiently provided. , 19 can be cooled.

  In addition, a nozzle 34 having a fixed orifice 33 that rotates together with the rotary shaft 29 is attached to an inlet portion of a through hole (refrigerant passage) 29 of the rotary shaft 13. Since a seal member 35 is provided for non-contact sealing with a labyrinth seal between the stationary refrigerant introduction path 31 and the rotary nozzle 34 without adding extra resistance to the rotary shaft 13. Can be sealed. Therefore, the refrigerant can be reliably guided into the through hole (refrigerant passage) 29 of the rotating shaft 13 without causing power loss.

  Furthermore, in this embodiment, a bearing box cooling mechanism for circulating the cooling oil from the cooling oil supply line 27 is provided in the oil grooves 25 and 26 provided on the outer periphery of the bearing boxes 16 and 18 where the rolling bearings 17 and 19 are installed. The rolling bearings 17 and 19 can be cooled from the outer ring side via the boxes 16 and 18. For this reason, the cooling effect of the rolling bearings 17 and 19 can be further enhanced, the amount of oil supplied to the rolling bearings 17 and 19 can be maintained at the minimum amount of oil necessary for lubrication, and the inner and outer rings of the rolling bearings 17 and 19 can be maintained. The temperature difference can be made as small as possible. Therefore, the mechanical loss of the rolling bearings 17 and 19 can be further reduced.

Further, from either position (A) to (E) of the refrigeration cycle, high pressure or intermediate pressure energy of the refrigerant, or a part of the high pressure liquid refrigerant or low pressure liquid refrigerant is extracted using a pump or an eductor, The rotating shaft 13 and the rolling bearings 17 and 19 can be cooled using the refrigerant as a cooling medium. Therefore, the refrigerant taken out from the turbo refrigerator itself can be effectively used for cooling the rolling bearings 17 and 19.
Furthermore, since the refrigeration cycle can be configured using the high-performance turbo compressor 1 that has been speeded up and miniaturized as described above, the small-sized high-performance and low-cost turbo chiller 40 can be manufactured.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG.
The present embodiment differs from the first embodiment in the configuration of a hole (refrigerant passage) 59 formed in the rotating shaft 13. Since other points are the same as those in the first embodiment, description thereof will be omitted. In the first embodiment, the through hole 29 (refrigerant passage) is provided so as to penetrate from one end side of the rotating shaft 13 to the other end side. However, in this embodiment, a hole (refrigerant passage) drilled in the rotating shaft 13 is provided. 59 is from the motor side end to the front side (II position shown in FIG. 2) where the second stage impeller 15 is provided. Then, at this II position, as shown in FIGS. 9A and 9B, a plurality of (two or four in the illustrated example) communication holes 60 are balanced with respect to the axial center in the radial direction. Are drilled. The communication hole 60 is opened to the oil drain space 2C in the housing 2.

  Further, in the present embodiment, the flow rate adjustment valve 32 provided in the refrigerant introduction system path 31 further detects the outer ring temperature of the rolling bearings 17 and 19 by a temperature sensor (not shown) after satisfying the above control conditions, It is controlled so that it is below a preset reference temperature. Thereby, the minimum flow rate of the refrigerant is determined, and the outer ring temperature of the bearing can be ensured. The oil discharge space 2C is communicated with the refrigerant suction passage 5 of the compressor 1 via the pressure equalizing passage 61, and is maintained in a low pressure state.

  According to the present embodiment, the refrigerant extracted from the refrigeration cycle of the turbo chiller 40 is introduced into the hole (refrigerant passage) 59 of the rotating shaft 13 via the refrigerant introduction system path 31 and evaporated in the hole 59. Thus, the rotating shaft 13 and the rolling bearings 17 and 19 are cooled. The refrigerant evaporated in the hole 59 flows out from the hole 59 into the oil drain space 2C of the housing 2 through the communication hole 60. Since the flow rate of the refrigerant gas is reduced in the oil discharge space 2 </ b> C, when the liquid component is contained, it is separated, and only the gas component is sucked into the refrigerant of the compressor 1 through the pressure equalizing passage 61. It is sucked into the road 5. Therefore, according to the present embodiment, in addition to the same effects as the first embodiment, the liquid compression generated by the return of the refrigerant supplied to the cooling of the rotating shaft 13 and the rolling bearings 17 and 19 is performed. The effect that it can prevent reliably is show | played.

  The present invention is not limited to the invention according to the above-described embodiment, and can be appropriately modified without departing from the gist thereof. For example, although the two-stage turbo compressor has been described in the above embodiment, the present invention is not limited to this, and the present invention can be similarly applied to a one-stage or three-stage or more multi-stage turbo compressor. In the above embodiment, cooling oil is supplied to the oil grooves 25 and 26 provided on the outer periphery of the bearing housings 16 and 18 to cool the outer ring side of the rolling bearings 17 and 19. Instead of the cooling oil, a refrigerant extracted from a refrigeration cycle may be used. Furthermore, the amount of heat generated and the amount of refrigerant necessary for cooling may be calculated in accordance with the rotational speed of the compressor, and the flow rate adjustment valve 32 may be controlled. You may make it stop.

1 is a longitudinal sectional view of a turbo compressor according to a first embodiment of the present invention. FIG. 2 is a side view of the turbo compressor shown in FIG. 1 with only a rotating shaft system taken out. It is a fragmentary longitudinal cross-sectional view near the suction inlet of the turbo compressor shown in FIG. It is a refrigerating cycle figure of the turbo refrigerator using the turbo compressor concerning a 1st embodiment of the present invention. It is detail drawing of the Example (A) and (B) of refrigerant | coolant extraction from the refrigerating cycle shown in FIG. It is detail drawing of the Example (C) of the refrigerant | coolant extraction from the refrigerating cycle shown in FIG. It is detail drawing of the Example (D) of the refrigerant | coolant extraction from the refrigerating cycle shown in FIG. It is detail drawing of the Example (E) of the refrigerant | coolant extraction from the refrigerating cycle shown in FIG. It is a longitudinal cross-sectional view of Example (A) from which the rotating shaft differs in the turbo compressor concerning 2nd Embodiment of this invention, (B).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbo compressor 2 Housing 2C Oil drain space 3 Electric motor 13 Rotating shaft 14 First stage impeller 15 Second stage impeller 16, 18 Bearing box 17, 19 Rolling bearing 25, 26 Oil groove 27A, 27B Cooling oil supply line 29 Through-hole (refrigerant passage)
30 Rotating shaft cooling mechanism 31 Refrigerant introduction path 32 Flow rate adjusting valve 33 Fixed orifice 35 Sealing member 40 Turbo refrigerator 41 Condenser 41A Liquid reservoir 43 Economizer 43A Economizer (intercooler)
43B economizer (gas-liquid separator)
45 Evaporator 45A Liquid reservoir 46 Subcooler 50A Pump 50B Ejector 59 Hole (refrigerant passage)
60 communication hole 61 pressure equalizing passage

Claims (15)

In a turbo compressor in which an impeller is provided at least at one end of a rotating shaft that is rotatably supported by a housing via a bearing and rotated by a drive source,
Wherein the axis of rotation, characterized in that the inside shaft refrigerant extracted from the refrigeration cycle of the turbo chiller and cooling medium, the rotary shaft cooling mechanism is provided for cooling the vicinity of at least the support by the bearing portion of the rotary shaft And turbo compressor.   2. The turbo compressor according to claim 1, wherein the rotating shaft cooling mechanism includes a refrigerant passage that is drilled along an axial direction in an axial center of the rotating shaft and through which the refrigerant flows.   The refrigerant passage is provided so as to penetrate from one end side of the rotating shaft to the other end side, and the refrigerant evaporated in the refrigerant passage flows from the impeller side end portion of the rotating shaft to the refrigerant suction passage of the compressor The turbo compressor according to claim 2, wherein the turbo compressor is discharged into the inside.   The refrigerant passage is drilled from one end side to the other end side of the rotating shaft, and communicates with an oil drain space in the housing before a position where the impeller is provided. The turbo compressor according to claim 2, wherein the evaporated refrigerant is led to the refrigerant suction passage of the compressor through the pressure equalizing passage after flowing out into the oil discharge space.   The inlet of the refrigerant passage is provided with a fixed throttle for reducing the refrigerant introduced from the refrigeration cycle to a low-temperature and low-pressure refrigerant, and the refrigerant reduced in pressure by the fixed throttle is introduced into the refrigerant passage. The turbo compressor according to any one of claims 2 to 4.   The rotary shaft cooling mechanism includes a refrigerant introduction system path that guides the refrigerant extracted from the refrigeration cycle to the refrigerant path of the rotary shaft, and the refrigerant introduction system path is provided with a flow rate adjusting valve that adjusts a refrigerant flow rate. The turbo compressor according to any one of claims 2 to 5, wherein   The flow rate control valve returns the refrigerant evaporated after cooling the rotating shaft to the refrigerant suction passage of the compressor, and the refrigerant temperature in the vicinity where the refrigerant merges with the refrigerant sucked into the compressor is equal to or higher than the pressure saturation temperature. The turbo compressor according to claim 6, wherein the turbo compressor is controlled as follows.   The rotary shaft cooling mechanism is attached to the refrigerant passage inlet of the rotary shaft, has a nozzle having the fixed throttle that rotates together with the rotary shaft, an outer peripheral surface of the nozzle as a seal surface, and the refrigerant introduction passageway The turbo compressor according to claim 6, further comprising a sealing member that performs non-contact sealing between the two.   9. The turbo according to claim 1, wherein the bearing is installed in the housing via a bearing box, and the bearing box is provided with a bearing box cooling mechanism for cooling the bearing. Compressor.   The turbo compressor according to claim 9, wherein the bearing box cooling mechanism uses a refrigerant extracted from a refrigeration cycle of the turbo refrigerator or a cooling oil for lubrication as a cooling medium.   The turbo compressor according to claim 1, wherein the refrigerant is extracted from a reservoir of a condenser that constitutes the refrigeration cycle.   The turbo compressor according to any one of claims 1 to 10, wherein the refrigerant is extracted from an outlet of a subcooler for cooling the liquid refrigerant constituting the refrigeration cycle.   The turbo compressor according to any one of claims 1 to 10, wherein the refrigerant is extracted from an outlet of an economizer constituting the refrigeration cycle.   The said refrigerant | coolant is extracted from the refrigerant | coolant liquid reservoir of the evaporator which comprises the said refrigerating cycle through the pump or the eductor which uses a high pressure refrigerant gas as a drive source. Turbo compressor. A turbo refrigeration machine comprising the turbo compressor according to any one of claims 1 to 14 as a turbo compressor constituting a refrigeration cycle.

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