JP2019090602A - Turbo refrigerator - Google Patents

Abstract

To provide a turbo refrigerator capable of reducing the environmental load by utilizing characteristics of R1233zd(E) refrigerant in which low pressure refrigerant becomes negative pressure at 18°C or less of saturation temperature while the frequency of maintenance is reduced due to oil-less operation and the occasion of refrigerant discharge is reduced due to the maintenance.SOLUTION: A turbo refrigerator comprises: a turbo compressor 2; a condenser; a decompression device; and an evaporator, which are connected in series via piping so as to constitute a refrigerating cycle, the refrigerating cycle being filled with refrigerant, in which the refrigerant is R1233zd(E) refrigerant which is low pressure refrigerant with a low global warming coefficient and a low ozone destruction coefficient; the turbo compressor 2 is a direct-coupled structure turbo compressor 2 in which the axis 18 of revolution of impellers 15 and 17 is directly connected to a motor 19; and the bearing supporting the axis 18 of revolution comprises magnet bearings 20, 21, 23, and 24.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a turbo refrigerator in which the environmental load is reduced by using R1233zd (E) refrigerant having low global warming potential (GWP) and low ozone depletion potential (ODP).

  In the turbo refrigerator, HFC refrigerants such as R134a are currently used. It is known that this HFC refrigerant has a high global warming potential (GWP) although it has an ozone depletion potential (ODP) of zero. Also, with turbo chillers, regular maintenance for bearing replacement, lubricating oil replacement, oil filter replacement, etc. is essential, and at that time, the refrigerant in the refrigeration cycle is recovered for maintenance. There are refrigerants that can not be recovered from inside the refrigerator and refrigerants that are dissolved in lubricating oil, and some of the refrigerant may be released to the atmosphere. Although there is no particular problem with the law, this is not preferable from the viewpoint of global warming.

  On the other hand, in some turbo refrigerators, the lubricating oil system is omitted by oil-free operation, and the high compression ratio and suction air flow are increased by increasing the rotation speed of the compressor, and the motor is miniaturized and bearings are increased by increasing the rotation speed of the motor. In order to reduce loss, improve reliability by simplifying components, reduce cost, etc., while adopting the motor direct coupling structure of the compressor in which the rotary shaft of the impeller (impeller) is directly connected to the motor, What is supported by a magnetic bearing is provided (see, for example, Patent Documents 1 and 2). However, in many turbo chillers, the configuration is still such that the impeller rotation shaft is driven by the motor shaft via the speed-increasing gear. In this case, a lubricating oil system for cooling and lubricating the speed-increasing gear is essential, and maintenance such as replacement of lubricating oil and replacement of an oil filter can not be avoided.

  Under these circumstances, R1233zd (E) refrigerants have recently attracted attention, which have characteristics of a GWP of 5 or less, an ODP of 0.00031, both low, and a negative pressure at a saturation temperature of 18 ° C. or less. This R1233zd (E) refrigerant is a low-pressure refrigerant with low density, and conventionally used mainly as a urethane foaming agent, but since it can reduce the environmental burden, it is one of the HCFO (hydrochlorofluoroolefin) refrigerants. As one, application to a refrigerator is being considered.

Patent No. 2809346 gazette JP, 2013-122331, A

  In particular, R1233zd (E) refrigerant, one of the HCFO refrigerants attracting attention as a low GWP refrigerant, has low GWP and ODP and is preferable for reducing environmental load, while it is a low pressure refrigerant and has a density Because it is low (about one-fifth of the R134a refrigerant), it is difficult to secure the capacity in a refrigerator, air conditioner or heat pump that uses a scroll-type or rotary-type positive displacement compressor, Was considered difficult.

  However, a turbo compressor, which is a centrifugal compressor, has a feature of being suitable for high flow rate refrigerant compression. The inventors paid attention to this point, and by applying to a refrigerator equipped with a turbo compressor, it is a low-pressure refrigerant and has a low density, and a negative pressure when the saturation temperature is 18 ° C. or less, R1233zd (E ) Considering that the characteristics of the refrigerant can be utilized, as a result of repeated investigations, by applying to a turbo refrigerator equipped with a turbo compressor having a specific structure, the environment utilizing the characteristics of the R1233 zd (E) refrigerant We have found the possibility of providing a turbo refrigerator that can reduce the load.

  The present invention has been made in view of the above circumstances, and the oilless operation reduces the frequency of maintenance and the opportunity for refrigerant release due to maintenance, and the low pressure refrigerant has a negative pressure when the saturation temperature is 18 ° C. or less R1233zd ( E) The object is to provide a turbo refrigerator that can reduce the environmental load by utilizing the characteristics of the refrigerant.

In order to solve the above-mentioned subject, the turbo refrigerator of the present invention adopts the following means.
That is, in the turbo refrigerator according to the present invention, a closed cycle refrigeration cycle is configured by sequentially connecting a turbo compressor, a condenser, a pressure reducing device and an evaporator via a pipe, and the refrigerant is charged in the cycle. In the turbo refrigerator, the refrigerant is a low-pressure refrigerant having a low global warming potential and an ozone destruction coefficient as R1233zd (E) refrigerant, and the turbo compressor directly connects the rotating shaft of the impeller to the motor A turbo compressor having a direct connection structure is provided, and a bearing for supporting the rotating shaft is a magnetic bearing.

  According to the present invention, the refrigerant is a low pressure refrigerant having low global warming potential and low ozone destruction coefficient as R1233zd (E) refrigerant, and the turbo compressor is a direct connected turbo compressor in which the rotary shaft of the impeller is directly connected to the motor. Since the bearing that supports the rotating shaft is a magnetic bearing, the turbo compression that is suitable for the compression of a large flow of refrigerant by reducing the power loss in the speed-up gear and the bearing loss in the rolling bearing etc. R1233zd (E) refrigerant, which is considered to be difficult to secure its capacity because it is a low-pressure refrigerant with low density and high sound velocity compared to a conventional HFC refrigerant, by enabling higher rotational speed of the machine. It is possible to cover the weak points of the oil, and eliminate the need for speed-up gears and rolling bearings that require oil lubrication to make the It can be omitted the maintenance of lubricating oil system and the like. Therefore, even if it is a low pressure refrigerant and low density R1233zd (E) refrigerant is applied, the required capacity can be secured. In addition, reduce the environmental load by reducing the frequency of maintenance and the opportunity for refrigerant discharge due to maintenance and taking advantage of the characteristics of the refrigerant that becomes a negative pressure at a saturation temperature of 18 ° C or less, and preventing the refrigerant from being released to the atmosphere. It is possible to simplify the configuration by omitting the lubricating oil system and to provide a low cost and highly reliable turbo chiller.

  Further, in the turbo refrigerator according to the present invention, a closed cycle refrigeration cycle is configured by sequentially connecting a turbo compressor, a condenser, a pressure reducing device, and an evaporator via a pipe, and the refrigerant is charged in the cycle. In the turbo refrigerator, the refrigerant is a low-pressure refrigerant having a low global warming potential and an ozone destruction coefficient as R1233zd (E) refrigerant, and the turbo compressor directly connects the rotating shaft of the impeller to the motor It is characterized in that it is a turbo compressor having a direct connection structure, and the bearing for supporting the rotating shaft is an oil-less ceramic bearing.

  According to the present invention, the refrigerant is a low pressure refrigerant having low global warming potential and low ozone destruction coefficient as R1233zd (E) refrigerant, and the turbo compressor is a direct connected turbo compressor in which the rotary shaft of the impeller is directly connected to the motor. Since the bearing that supports the rotary shaft is an oil-less ceramic bearing, the power loss in the speed-up gear and the bearing loss in the rolling bearing, etc. are reduced to compress the large flow rate refrigerant. By enabling further high rotation of a suitable turbo compressor, it is considered to be difficult to secure the ability because it is a low pressure refrigerant with low density and a high sound velocity compared to a conventional HFC refrigerant. R1233zd (E) can cover the weakness of refrigerants and use ceramic bearings to eliminate the need for speed-up gears that require oil lubrication and make them oil-less And it makes it possible to omit the maintenance such as replacement of the exchange and the oil filter of the lubricating oil. Therefore, even if the low-pressure refrigerant and the low density R1233zd (E) refrigerant are applied, the required capacity can be secured. In addition, the frequency of maintenance and the opportunity to release the refrigerant due to maintenance are greatly reduced, and by utilizing the characteristics of the refrigerant that has a negative pressure when the saturation temperature is 18 ° C or less, the environmental load is reduced by preventing the refrigerant from being released into the atmosphere. It is possible to simplify the configuration by omitting the lubricating oil system and to provide a low cost and highly reliable turbo refrigerator.

  Furthermore, according to the turbo refrigerator of the present invention, in the above-described turbo refrigerator, the liquid refrigerant can be circulated as a cooling and lubricating medium from the refrigeration cycle side to the bearing box of the bearing and the air gap portion of the motor. It is characterized by being.

  According to the present invention, since the liquid refrigerant can be circulated as a cooling / lubricating medium from the refrigeration cycle side to the bearing box of the bearing and the air gap portion of the motor, the bearing made of ceramic material can be The durability can be improved by cooling and lubricating with the refrigerant, and the cooling performance is secured by cooling the motor having a high rotation speed with the liquid refrigerant, and the heat loss and the temperature rise of the motor increase. It is possible to prevent the suspension of protection. Therefore, even if oil-less, it is possible to sufficiently cool and lubricate bearings and motors, and it is possible to provide a high-performance, high-reliability, low-environmental-impact turbo refrigerator with improved durability and performance. .

  Furthermore, the turbo refrigerator according to the present invention is characterized in that, in the above-described turbo refrigerator, a low pressure gas refrigerant can be supplied to the air gap portion of the motor instead of the liquid refrigerant.

  According to the present invention, the low-pressure gas refrigerant can be supplied instead of the liquid refrigerant to the air gap portion of the motor. Therefore, when the low-pressure gas refrigerant is supplied as the cooling medium, the liquid refrigerant is supplied. In comparison, stirring loss due to the motor can be reduced. Therefore, the motor can be sufficiently cooled to reduce the heat loss and the like, and the stirring loss can be further reduced to enhance the motor efficiency and achieve a higher rotation.

  Furthermore, in the turbo refrigerator according to the present invention, in any one of the above-described turbo refrigerator, at least one of the stator inner peripheral surface, the rotor outer peripheral surface, or the outer peripheral surface of a balance ring provided on the rotor end surface of the motor As described above, it is characterized in that there is provided a spiral groove for circulating the liquid refrigerant or low-pressure gas refrigerant supplied to the air gap portion of the motor to the axial direction outer side.

  According to the present invention, the liquid refrigerant supplied to the air gap portion of the motor or at least one of the stator inner peripheral surface, the rotor outer peripheral surface, or the outer peripheral surface of the balance ring provided on the rotor end surface Since the helical groove which circulates the low pressure gas refrigerant to the axial direction outer side is provided, the refrigerant supplied to the air gap part can be circulated axially outward by the helical groove and can be discharged quickly. Therefore, the cooling effect of the motor by the refrigerant can be further improved, and the windage loss of the motor due to the stirring of the refrigerant can be reduced, and the efficiency of the motor can be further enhanced.

  According to the present invention, by reducing the power loss in the speed-increasing gear and the bearing loss in the rolling bearing etc., it is possible to further increase the rotation speed of the turbo compressor suitable for the compression of a large flow of refrigerant. Because it is a low-pressure refrigerant with low density and high sound velocity compared to the conventional HFC refrigerant, it is possible to cover the weakness of R1233zd (E) refrigerant, which has been considered difficult to secure its capacity, and oil lubrication It is possible to eliminate maintenance such as replacement of lubricating oil and oil filter by eliminating the speed-increasing gear and the rolling bearing that require the above, or by using the ceramic material bearing to make it oil-less. In addition, the frequency of maintenance and the opportunity to release the refrigerant due to maintenance are greatly reduced, and by utilizing the characteristics of the refrigerant that has a negative pressure when the saturation temperature is 18 ° C or less, the environmental load is reduced by preventing the refrigerant from being released into the atmosphere. It is possible to simplify the configuration by omitting the lubricating oil system and to provide a low cost and highly reliable turbo refrigerator.

It is a block diagram of the turbo refrigerator concerning a 1st embodiment of the present invention. It is a schematic block diagram of the turbo compressor applied to the said turbo refrigerator. It is a schematic block diagram of the turbo compressor concerning 2nd Embodiment of this invention. It is the elements on larger scale of the drive motor of the turbo compressor shown in FIG.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
First Embodiment
Hereinafter, a first embodiment of the present invention will be described using FIGS. 1 and 2.
FIG. 1 shows a block diagram of a turbo refrigerator according to the first embodiment, and FIG. 2 shows a schematic block diagram of a turbo compressor applied thereto.
As shown in FIG. 1, the turbo refrigerator 1 includes a turbo compressor 2, a condenser 3, a first pressure reducing device 4, a gas-liquid separator 5 functioning as an economizer, and a second pressure reducing device 6. A closed cycle refrigeration cycle 9 configured by being sequentially connected to the evaporator 7 via a refrigerant pipe (pipe) 8 is provided.

  The refrigeration cycle 9 of the present embodiment injects the gas refrigerant separated by the gas-liquid separator 5 into the intermediate pressure refrigerant compressed by the low-stage compressor 14 of the turbo compressor 2 through the intermediate port. A known economizer circuit 10 is provided. Although this economizer circuit 10 is a gas-liquid separation type economizer circuit 10 using a gas-liquid separator 5, a part of the refrigerant condensed and liquefied by the condenser 3 is divided and the refrigerant is depressurized. It is good also as an economizer circuit of the intercooler system which provided the intercooler which carries out heat exchange with liquid refrigerant. The economizer circuit 10 is not essential in the present invention.

  In the above-described refrigeration cycle 9, the global warming potential (GWP) is 5 or less, the ozone destruction coefficient (ODP) is 0.00031, both of which are low, and the saturation temperature is negative pressure at 18 ° C. or less. The required amount of R1233zd (E) refrigerant is filled. This R1233zd (E) refrigerant is one of the low GWP refrigerants, HCFO (hydrochlorofluoroolefin) refrigerant, is a low-pressure refrigerant and has a low density, and is one of the HFC refrigerants used in the current turbo refrigerator. It is known that the density is about one fifth of that of the R134a refrigerant.

In this embodiment, the turbo compressor 2 incorporated in the turbo refrigerator 1 filled with the R1233zd (E) refrigerant is a turbo compressor 2 having the following configuration.
A schematic block diagram of the turbo compressor 2 is shown in FIG.
As known, the turbo compressor 2 centrifugally compresses a low pressure refrigerant gas into a high pressure refrigerant gas by a rotating impeller (impeller) to circulate the refrigerant cycle 9.

  Here, the turbo compressor 2 is driven by the motor 19, and the rotary shaft 18 for rotating the two-stage low-stage and high-stage impellers (impellers) 15 and 17 is directly connected to the rotor 19A of the motor 19. In addition to the direct coupling structure, the rotary shaft 18 is rotatable relative to the housing 11 via a pair of front and rear radial magnetic bearings 20 and 21 and a pair of thrust magnetic bearings 23 and 24 disposed opposite to each other. It is considered as a turbo compressor 2 of a supported configuration.

  That is, the turbo compressor 2 includes the housing 11 in which the compressor housing 11A and the motor housing 11B are integrated, and low-pressure gas refrigerant evaporated in the evaporator 7 is supplied from the refrigerant suction port 12 through the inlet vane 13. Two-stage compression is performed by the low stage side compression unit 14 having the low stage side impeller 15 and the high stage side compression unit 16 having the high stage side impeller 17, and the gas refrigerant of high temperature and high pressure is externally discharged from the discharge port of the scroll casing. The refrigerant gas is discharged to the condenser 3, and the refrigerant gas at the intermediate pressure from the economizer circuit 10 is injected between the low-stage compression unit 14 and the high-stage compression unit 16 through the intermediate port. There is.

  The two-stage low-stage impeller 15 and the high-stage impeller 17 are integrally connected to one end of the rotating shaft 18 at a predetermined distance, and the rotating shaft 18 is further connected to the rotor 19A of the motor 19. Thus, the rotary shaft 18 of the impellers 15 and 17 is directly connected to the motor 19. Further, the motor 19 includes a rotor 19A and a stator 19B, is housed and installed substantially at a central portion in the motor housing 11B, and is configured to variably control the rotational speed via an inverter (not shown).

  Further, the rotary shaft 18 is rotatably supported by a pair of radial magnetic bearings 20, 21 provided at the front and rear of the motor 19, and the thrust disk 22 is fixedly installed at the rear end. The thrust magnetic bearings 23 and 24 are supported by being disposed so as to face each other. The pair of thrust magnetic bearings 23 and 24 generate a magnetic attraction force by the current supplied to the coils, and support the thrust load applied to the rotating shaft 18 by positioning the thrust disk 22 at the central portion thereof. It is.

According to the configuration described above, according to the present embodiment, the following effects can be obtained.
In the turbo refrigerator 1, when the turbo compressor 2 is driven, a low pressure gas refrigerant evaporated in the evaporator 7 is sucked from the suction port 12 through the inlet vane 13. The low-pressure refrigerant is centrifuged at two stages, from low pressure to intermediate pressure and from intermediate pressure to high pressure, by the low-stage impeller 15 and the high-stage impeller 17 rotating in high stages in the low-stage compression section 14 and high-stage compression section 16 respectively. After being compressed and discharged into the scroll casing, the pressure is sent from there to the condenser 3 outside.

  The refrigerant condensed in heat exchange with the cooling medium in the condenser 3 is supercooled via the first pressure reducing device 4, the gas-liquid separator 5 functioning as an economizer, and the second pressure reducing device 6, and the pressure is reduced to low pressure. It is led to the evaporator 7. The low-pressure liquid refrigerant led to the evaporator 7 exchanges heat with the medium to be cooled, thereby absorbing heat from the medium to be cooled and cooling the medium to be cooled. Repeat the operation of being sucked and compressed by 2.

  Further, the refrigerant which has been separated and evaporated in the gas-liquid separator 5 and has subcooled the liquid refrigerant is an intermediate pressure refrigerant compressed by the lower stage compression section 14 from the intermediate port of the turbo compressor 2 via the economizer circuit 10 By being injected into the gas, it acts as an economizer that improves the refrigeration capacity.

  The refrigeration cycle 9 of the turbo refrigerator 1 is filled with R1233zd (E) refrigerant, which is a low pressure refrigerant having a low global warming potential (GWP) and an ozone destruction coefficient (ODP) and a low density. Such refrigerants are considered to have difficulty in securing the refrigeration capacity, but in the present embodiment, the turbo compressor 2 suitable for high-flow-rate refrigerant compression is further used as the motor 19 for the rotary shaft 18 of the impellers 15 and 17. The turbo compressor 2 having a directly connected structure is incorporated, and the rotary shaft 18 is incorporated as a turbo compressor 2 configured to be supported by radial magnetic bearings 20 and 21 and thrust magnetic bearings 23 and 24.

  For this reason, the low pressure refrigerant is achieved by reducing the power loss in the speed-increasing gear and the bearing loss in the rolling bearings and the like to further increase the rotation speed of the turbo compressor 2 suitable for compressing a large flow of refrigerant. The density is low, and the sound velocity is high compared to the HFC refrigerant, so it is possible to cover the weaknesses of using the R1233zd (E) refrigerant, which was considered difficult to secure the capacity, and it is possible to use oil lubrication. The maintenance of the lubricating oil system such as replacement of the lubricating oil and the oil filter can be omitted by eliminating the necessary speed-increasing gear, rolling bearing and the like to make the oil-less.

  As a result, the required capacity can be secured even if it is a low pressure refrigerant and low density R1233zd (E) refrigerant is applied, and the frequency of maintenance and the opportunity of refrigerant discharge due to maintenance are reduced, and the saturation temperature is 18 It is possible to provide the turbo refrigerator 1 in which the environmental load is reduced by preventing the discharge of the refrigerant into the atmosphere by making use of the characteristics of the refrigerant which has a negative pressure at 0 ° C. or less. Further, the lubricating oil system can be omitted to simplify the configuration, and a low cost and highly reliable turbo refrigerator 1 can be provided.

  In the above embodiment, the example of the turbo compressor 2 performing two-stage compression has been described, but in the present invention, the turbo compressor 2 is not limited to two-stage compression, but may be single-stage compression or three or more stages. The turbo compressor 2 may be a multi-stage compression type turbo compressor, and the main point is that the turbo compressor 2 is a direct-coupled turbo compressor 2 in which the rotary shaft 18 of the impeller (impeller) is directly connected to the motor 19. May be supported by magnetic bearings.

Second Embodiment
Next, a second embodiment of the present invention will be described using FIGS. 3 and 4.
The present embodiment differs from the above-described first embodiment in that the bearings that rotatably support the rotating shaft 18 are oil-less ceramic bearings 25 and 26. The other points are the same as in the first embodiment, and thus the description thereof is omitted.
In the present embodiment, the bearings for rotatably supporting the rotating shaft 18 are replaced with the radial magnetic bearings 20, 21 and the thrust magnetic bearings 23, 24, and as shown in FIG. The roller bearings 25 and 26 (hereinafter, referred to as ceramic material bearings in the present invention) are used.

  Here, the ceramic bearings 25 and 26 are made of silicon nitride, and ensure high durability and can extend the life even without oil. In this embodiment, the ceramic bearings 25 and 26 can be cooled and lubricated through the liquid refrigerant extracted from the refrigeration cycle 9 side. That is, the refrigerant extraction pipe 27 extracts part of the high pressure liquid refrigerant condensed or liquefied by the condenser 3 from the refrigeration cycle 9 side or part of the low pressure liquid refrigerant from piping or equipment from the condenser 3 to the evaporator 7 The flow rate of the liquid refrigerant is adjusted by the flow control valve 28 and supplied to the bearing boxes 25A and 26A of the ceramic bearings 25 and 26 so that the ceramic bearings 25 and 26 can be cooled and lubricated by the liquid refrigerant. ing.

  Further, in this embodiment, a part of the liquid refrigerant introduced through the refrigerant extraction pipe 27 and the flow control valve 28 so that the motor 19 can be cooled not only by the ceramic bearings 25 and 26 but also by the liquid refrigerant. Is introduced into the air gap portion 19D of the motor 19 through the refrigerant injection hole 19C provided in the stator 19B of the motor 19 so that both the rotor 19A and the stator 19B can be cooled. The refrigerant that has cooled the ceramic bearings 25 and 26 and the motor 19 is collected in the refrigerant reservoir 29 of the motor housing 11B and returned to the low pressure region of the evaporator 7 etc. on the refrigeration cycle 9 side via the refrigerant discharge pipe 30. It is supposed to be.

  Furthermore, in order to quickly discharge the liquid refrigerant introduced into the air gap portion 19D to reduce the windage loss in the motor 19, as shown in FIG. 4, the outer peripheral surface of the rotor 19A in the motor 19, the stator 19B A spiral groove that causes the liquid refrigerant supplied to the air gap portion 19D to flow outward in the axial direction on at least one of the inner peripheral surface or the outer peripheral surface of the balance ring 31 provided on the end face of the rotor 19A. 32A, 32B, and 32C are provided. The spiral grooves 32A, 32B and 32C are considered to be most preferable in view of processing from the spiral groove 32C provided on the outer peripheral surface of the balance ring 31.

  As described above, also by using the oil-less ceramic bearings 25 and 26 as the bearings for supporting the rotary shaft 18, as in the first embodiment, the power loss in the speed-increasing gear, the bearing in the rolling bearings, etc. By reducing the loss and further increasing the rotation speed of the turbo compressor 2 suitable for high flow rate refrigerant compression, it is a low pressure refrigerant with a low density, and a high sound velocity as compared with the HFC refrigerant, It is possible to cover the weaknesses of using R1233zd (E) refrigerant, which has been considered difficult to secure its capacity, and eliminate the speed-up gears and rolling bearings that require oil lubrication to make it oil-less As a result, maintenance of the lubricating oil system such as replacement of lubricating oil or oil filter can be omitted.

  For this reason, even if it is a low-pressure refrigerant and the low density R1233zd (E) refrigerant is applied, the required capacity can be secured, and the frequency of maintenance and the opportunity for refrigerant discharge due to maintenance are reduced It is possible to provide the turbo refrigerator 1 in which the environmental load is reduced by preventing the discharge of the refrigerant into the atmosphere by making use of the characteristics of the refrigerant which has a negative pressure at 0 ° C. or less. Further, the lubricating oil system can be omitted to simplify the configuration, and a low cost and highly reliable turbo refrigerator 1 can be provided.

  Further, with respect to the bearing boxes 25A and 26A of the ceramic bearings 25 and 26 and the air gap portion 19D of the motor 19, the liquid refrigerant through the refrigerant extraction pipe 27, the flow control valve 28 and the refrigerant discharge pipe 30 from the refrigeration cycle 9 side. The motor can be circulated as a cooling / lubricating medium, so that the durability can be improved by cooling / lubricating the ceramic bearings 25 and 26 with liquid refrigerant, and the motor 19 can be highly rotated. By cooling the liquid with liquid refrigerant, the cooling performance can be secured, and the heat loss and the protection stop can be suppressed. Therefore, even if oil-less, the ceramic bearings 25 and 26 and the motor 19 can be sufficiently cooled and lubricated, and their performance and performance are improved. Machine 1 can be provided.

  Furthermore, in the above embodiment, the air gap of the motor 19 is at least one of the inner peripheral surface of the stator 19B of the motor 19, the outer peripheral surface of the rotor 19A, or the outer peripheral surface of the balance ring 31 provided on the rotor end surface. There are provided spiral grooves 32A, 32B, 32C which allow the liquid refrigerant supplied to the portion 19D to flow outward in the axial direction. Therefore, the liquid refrigerant supplied to the air gap portion 19D can be made to flow axially outward by the spiral grooves 32A, 32B, 32C, and can be quickly discharged. Therefore, the cooling effect of the motor 19 by the liquid refrigerant can be further improved, and the windage loss of the motor 19 by stirring the liquid refrigerant can be reduced, and the motor efficiency can be further enhanced.

  In the above embodiment, the motor 19 is cooled by introducing the high-pressure liquid refrigerant or the low-pressure liquid refrigerant from the refrigerant injection hole 19C, but instead of these liquid refrigerants, the low-pressure gas is evaporated by the evaporator 7. The structure may be such that the motor 19 is cooled by introducing a refrigerant. As described above, by introducing the low-pressure gas refrigerant as a cooling medium for the motor 19, the stirring loss due to the motor 19 can be reduced as compared with the case where the liquid refrigerant is introduced. As a result, heat loss and the like can be reduced, and the stirring loss can be further reduced to increase the efficiency of the motor 19 and achieve higher rotation.

  The present invention is not limited to the invention according to the above-described embodiment, and appropriate modifications can be made without departing from the scope of the invention. For example, although the above-mentioned embodiment explained an example applied to refrigeration cycle 9 provided with economizer circuit 10, of course, it is applicable also to a heat pump cycle of turbo heat pump. In the first embodiment, the magnetic bearings 20, 21, 23, 24 and the motor 19 may be configured to be cooled using a refrigerant as in the second embodiment.

DESCRIPTION OF SYMBOLS 1 turbo refrigerator 2 turbo compressor 3 condenser 4 1st pressure reduction apparatus 5 gas-liquid separator 6 2nd pressure reduction apparatus 7 evaporator 8 refrigerant piping (piping)
9 refrigeration cycle 14 low pressure side compression section 15 low pressure side impeller (impeller)
16 High-stage compression section 17 High-stage impeller (impeller)
Reference Signs List 18 rotary shaft 19 motor 19A rotor 19B stator 19C refrigerant injection hole 19D air gap portion 20, 21 radial magnetic bearings 23, 24 thrust magnetic bearings 25, 26 ceramic bearings 25A, 26A bearing box 27 refrigerant extraction pipe 28 flow control valve 29 Refrigerant reservoir 30 Refrigerant discharge pipe 31 Balance ring 32A, 32B, 32C Spiral groove

In order to solve the above-mentioned subject, the turbo refrigerator of the present invention adopts the following means.
That is, in the turbo refrigerator according to the present invention, a closed cycle refrigeration cycle is configured by sequentially connecting a turbo compressor, a condenser, a pressure reducing device and an evaporator via a pipe, and a single refrigerant is formed in the cycle. In the turbo refrigerator filled with the above, the single refrigerant is an R1233zd (E) refrigerant which is a low pressure refrigerant having a low global warming potential and an ozone destruction coefficient, and the turbo compressor is a rotary shaft of an impeller. A turbo compressor having a direct connection structure directly connected to a motor is provided, and a bearing for supporting the rotating shaft is a magnetic bearing.

Further, in the turbo refrigerator according to the embodiment of the present invention, a closed cycle refrigeration cycle is configured by sequentially connecting a turbo compressor, a condenser, a pressure reducing device, and an evaporator via a pipe, and in the cycle, In the turbo refrigerator filled with a refrigerant, the refrigerant is a low pressure refrigerant having a low global warming potential and an ozone destruction coefficient as R1233zd (E) refrigerant, and the turbo compressor is a motor having a rotating shaft of an impeller as a motor. The present invention is characterized in that the turbo compressor has a direct connection structure directly connected to the shaft, and the bearing for supporting the rotating shaft is an oil-less ceramic bearing.

According to the embodiment of the present invention, the refrigerant is a low-pressure refrigerant with low global warming potential and ozone depletion coefficient, R1233zd (E) refrigerant, and the turbo compressor has a direct coupling structure in which the rotating shaft of the impeller is directly coupled to the motor. Since a turbo compressor is used and the bearing that supports the rotary shaft is an oil-less ceramic bearing, the power loss in the speed-up gear and the bearing loss in the rolling bearing etc. are reduced, and a large flow of refrigerant It is a low-pressure refrigerant with low density and high sound velocity compared to conventional HFC refrigerants, which makes it difficult to secure the capacity by enabling higher rotational speeds of the turbo compressor suitable for the compression of It is possible to cover the weaknesses of R1233zd (E) refrigerant that has been used, use ceramic bearings, and omit the speed-up gears that require lubrication with oil. By gasification, it can be omitted the maintenance such as replacement of the exchange and the oil filter of the lubricating oil. Therefore, even if the low-pressure refrigerant and the low density R1233zd (E) refrigerant are applied, the required capacity can be secured. In addition, the frequency of maintenance and the opportunity to release the refrigerant due to maintenance are greatly reduced, and by utilizing the characteristics of the refrigerant that has a negative pressure when the saturation temperature is 18 ° C or less, the environmental load is reduced by preventing the refrigerant from being released into the atmosphere. It is possible to simplify the configuration by omitting the lubricating oil system and to provide a low cost and highly reliable turbo refrigerator.

According to the present invention and the embodiment of the present invention, the liquid refrigerant is circulated as a cooling / lubricating medium from the side of the refrigeration cycle to the bearing housing of the bearing and the air gap portion of the motor. The bearing can be cooled and lubricated with liquid refrigerant to improve its durability, and the motor with high rotation speed can be cooled with liquid refrigerant to secure the cooling performance, and the heat loss and so on. It is possible to prevent the protection stop due to the temperature rise of the motor. Therefore, even if oil-less, it is possible to sufficiently cool and lubricate bearings and motors, and it is possible to provide a high-performance, high-reliability, low-environmental-impact turbo refrigerator with improved durability and performance. .

According to the present invention and the embodiment of the present invention , further increase in the rotation speed of the turbo compressor suitable for compression of a large flow rate refrigerant by reducing power loss in the speed increasing gear and bearing loss in the rolling bearing etc. It is a low-pressure refrigerant with low density and high sound velocity compared to conventional HFC refrigerants, so it is possible to cover the weakness of R1233zd (E) refrigerant, which was considered difficult to secure its capacity. It is possible to eliminate maintenance gears, such as replacement of lubricating oil and oil filter, by eliminating speed-up gears and rolling bearings that require oil lubrication, or by using an oil bearing using ceramic bearings. it can. In addition, the frequency of maintenance and the opportunity to release the refrigerant due to maintenance are greatly reduced, and by utilizing the characteristics of the refrigerant that has a negative pressure when the saturation temperature is 18 ° C or less, the environmental load is reduced by preventing the refrigerant from being released into the atmosphere. It is possible to simplify the configuration by omitting the lubricating oil system and to provide a low cost and highly reliable turbo refrigerator.

It is a block diagram of the turbo refrigerator concerning a 1st embodiment of the present invention. It is a schematic block diagram of the turbo compressor applied to the said turbo refrigerator. It is a schematic block diagram of the turbo compressor concerning the reference embodiment of the present invention. It is the elements on larger scale of the drive motor of the turbo compressor shown in FIG.

[ Reference embodiment]
Next, a reference embodiment of the present invention will be described using FIGS. 3 and 4.
The present embodiment differs from the above-described first embodiment in that the bearings that rotatably support the rotating shaft 18 are oil-less ceramic bearings 25 and 26. The other points are the same as in the first embodiment, and thus the description thereof is omitted.
In this reference embodiment, by changing the bearing supporting the rotary shaft 18 rotatably in the radial magnetic bearings 20, 21 and the thrust magnetic bearing 23 and 24, as shown in FIG. 3, the oil-less ceramic material made sliding bearing Alternatively, the rolling bearings 25 and 26 (hereinafter, referred to as ceramic material bearings in the reference embodiment of the present invention) are used.

Claims (5)

In a turbo refrigerator in which a closed cycle refrigeration cycle is configured by sequentially connecting a turbo compressor, a condenser, a pressure reducing device and an evaporator via a pipe, and the cycle is filled with a refrigerant,
The refrigerant is an R1233zd (E) refrigerant which is a low pressure refrigerant having low global warming potential and low ozone depletion potential.
The turbo compressor is a turbo compressor having a direct connection structure in which the rotary shaft of the impeller is directly connected to a motor,
A turbo chiller characterized in that a bearing for supporting the rotating shaft is a magnetic bearing. In a turbo refrigerator in which a closed cycle refrigeration cycle is configured by sequentially connecting a turbo compressor, a condenser, a pressure reducing device and an evaporator via a pipe, and the cycle is filled with a refrigerant,
The refrigerant is an R1233zd (E) refrigerant which is a low pressure refrigerant having low global warming potential and low ozone depletion potential.
The turbo compressor is a turbo compressor having a direct connection structure in which the rotary shaft of the impeller is directly connected to a motor,
A turbo chiller characterized in that a bearing for supporting the rotating shaft is an oil-less ceramic bearing.   The turbo refrigerator according to claim 2, wherein the refrigerant liquid is configured to be circulated as a cooling / lubricating medium from the refrigeration cycle side to the bearing box of the bearing and the air gap portion of the motor. .   The turbo refrigerator according to claim 3, wherein a low pressure gas refrigerant can be supplied to the air gap portion of the motor instead of the refrigerant liquid. The refrigerant liquid or low-pressure gas refrigerant supplied to the air gap portion of the motor on at least one of the stator inner peripheral surface, the rotor outer peripheral surface, or the outer peripheral surface of the balance ring provided on the rotor end surface The turbo refrigerator according to claim 3 or 4, wherein a spiral groove is provided to flow in the axial direction to the outside.

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