JP2018068021A - Turbomachine and refrigeration cycle device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide technology for suppressing heat transfer from a motor to a working fluid in a turbomachine.SOLUTION: A motor (30) of a turbomachine in the present disclosure has: a shaft (10) including a plurality of ribs (36) extending in a longitudinal direction; a rotator (31) that has an inner-circumferential surface (31q) being in contact with the plurality of ribs (36) and is fixed to the shaft (10); a stator (32) arranged around the rotator (31); a clearance (37) that exists between the rotator (31) and the stator (32); a first flow channel (38) that is provided between the shaft (10) and the rotator (31) and exists between a rib (36) and a rib (36) adjacent to each other in a circumferential direction of the shaft (10); and a second flow channel (39) that passes through the rotator (31) to communicate the first flow channel (38) with the clearance (37) in a radial direction of the shaft (10).SELECTED DRAWING: Figure 3

Description

  The present disclosure relates to a turbo machine and a refrigeration cycle apparatus using the same.

  Induction motors are often used in turbomachines such as turbocompressors. The heat generation of the induction motor is generally larger than the heat generation of the synchronous motor due to loss due to rotational slip. Therefore, the ventilation hole extended in the direction parallel to a shaft is provided in the iron core which comprises a rotor, or the ventilation hole extended in radial direction is provided in an iron core. These ventilation holes contribute to the efficient cooling of the induction motor.

  6A is a longitudinal sectional view of a rotor of a conventional induction motor described in Patent Document 1. FIG. FIG. 6B is a cross-sectional view of the rotor taken along line AA. The rotor includes a disk 309 and iron cores 303 arranged on both sides of the disk 309. The disc 309 and the iron core 303 are fitted on the shaft 301. The iron core 303 is provided with a ventilation hole 308a. The circular plate 309 is also provided with a ventilation hole 308b. The circular plate 309 is provided with a ventilation hole 311 that is continuous with the ventilation hole 308b and extends in the radial direction. A conductor 304 is inserted into the disc 309 and the iron core 303.

JP-A-2-299436

  In turbomachines, it is important to cool the motor. If the motor is not sufficiently cooled, heat is actively transferred from the motor to the working fluid, resulting in various disadvantages.

  One object of the present disclosure is to provide a technique for suppressing heat transfer from a motor to a working fluid in a turbomachine.

That is, this disclosure
A motor,
An impeller fixed to the motor;
A turbomachine comprising:
The motor is
A shaft including a plurality of longitudinally extending ribs;
A rotor having an inner peripheral surface in contact with the plurality of ribs and fixed to the shaft;
A stator disposed around the rotor;
A gap between the rotor and the stator;
A first flow path provided between the rib and the rib provided between the shaft and the rotor and adjacent to each other in the circumferential direction of the shaft;
A second flow path penetrating the rotor from an inner peripheral surface of the rotor toward an outer peripheral surface of the rotor, and communicating the first flow path and the gap in the radial direction of the shaft;
A turbomachine is provided.

  According to the technology of the present disclosure, heat transfer from a motor to a working fluid can be suppressed in a turbo machine.

FIG. 1 is a configuration diagram of a refrigeration cycle apparatus according to an embodiment of the present disclosure. FIG. 2 is a longitudinal sectional view of a turbo compressor used in the refrigeration cycle apparatus shown in FIG. FIG. 3 is a cross-sectional view of the induction motor used in the turbo compressor shown in FIG. FIG. 4 is a perspective view of the shaft. FIG. 5 is a partially enlarged view of FIG. 6A is a longitudinal sectional view of a rotor of a conventional induction motor described in Patent Document 1. FIG. FIG. 6B is a partial cross-sectional view of the rotor along the line AA.

(Knowledge that became the basis of this disclosure)
In the motor, the contact area between the shaft and the rotor is large, and heat is easily transmitted from the rotor to the shaft. In a turbo machine, an impeller for compressing a working fluid is fixed to a shaft. When the rotor heat is transferred to the working fluid through the shaft and the impeller, the compression efficiency is reduced. Further, when the temperature of the bearing that supports the shaft increases, the lubricity of the bearing may also decrease. Therefore, in order to suppress heat transfer from the motor to the working fluid, it is important to suppress heat transfer from the rotor to the shaft.

The turbomachine according to the first aspect of the present disclosure is:
A motor,
An impeller fixed to the motor;
A turbomachine comprising:
The motor is
A shaft including a plurality of longitudinally extending ribs;
A rotor having an inner peripheral surface in contact with the plurality of ribs and fixed to the shaft;
A stator disposed around the rotor;
A gap between the rotor and the stator;
A first flow path provided between the rib and the rib provided between the shaft and the rotor and adjacent to each other in the circumferential direction of the shaft;
A second flow path penetrating the rotor from an inner peripheral surface of the rotor toward an outer peripheral surface of the rotor, and communicating the first flow path and the gap in the radial direction of the shaft;
It is what has.

  According to the first aspect, the outer peripheral surface of the rib is in contact with the inner peripheral surface of the rotor, whereby the rotor is fixed to the shaft. Since the contact area between the rotor and the shaft is small, the heat of the rotor is not easily transmitted to the shaft. Moreover, according to the 1st aspect, the length of the 2nd flow path regarding the radial direction of a shaft can fully be ensured. In this case, the centrifugal force acts on the larger volume of the cooling gas, so the pressure at the outlet of the second flow path increases, and the flow rate of the cooling gas flowing into the gap between the rotor and the stator increases. Therefore, the amount of heat released from the motor to the cooling gas also increases. Further, the first flow path is between the shaft and the rotor. Since a hole penetrating the rotor in the axial direction can be omitted, the magnetic flux is prevented from being saturated in the rotor. As a result, slip loss is reduced and heat generation of the motor is suppressed. Due to the combined effects described above, heat transfer from the motor shaft to the impeller is suppressed. That is, heat transfer from the motor to the working fluid is suppressed. As a result, a decrease in compression efficiency and a decrease in lubricity can be suppressed.

  In the second aspect of the present disclosure, for example, the plurality of ribs of the turbomachine according to the first aspect each extend in a spiral shape in the longitudinal direction of the shaft. According to the second aspect, the cooling gas is accelerated not only in the turning direction but also in the axial direction. As a result, the flow rate of the cooling gas in the first flow path increases.

  In the third aspect of the present disclosure, for example, the plurality of ribs of the turbomachine according to the first or second aspect are each in the longitudinal direction of the shaft at a twist angle opposite to the rotation direction of the shaft. It extends in a spiral. According to the 3rd aspect, the effect in a 2nd aspect is acquired more fully.

  In the fourth aspect of the present disclosure, for example, the motor of the turbomachine according to any one of the first to third aspects further includes a casing storing the shaft, the rotor, and the stator. The casing has, as its internal space, a first space adjacent to one end of the rotor in the longitudinal direction of the shaft and an other end of the rotor in the longitudinal direction of the shaft. The first flow path is opened in each of the first space and the second space. According to such a structure, the cooling gas is smoothly introduced into the gap between the rotor and the stator and the first flow path.

The refrigeration cycle apparatus according to the fifth aspect of the present disclosure is:
An evaporator for evaporating the refrigerant;
A compressor for compressing the refrigerant vaporized by the evaporator;
A condenser for condensing the refrigerant compressed by the compressor;
With
The compressor includes any one of the first to fourth turbomachines,
The refrigerant is used as a cooling gas for the motor.

  According to the fifth aspect, the same effect as described in the first aspect can be obtained. Furthermore, since the refrigerant of the refrigeration cycle apparatus is used as the cooling gas for the motor, no special sealing structure is required.

  In the sixth aspect of the present disclosure, for example, the compressor of the refrigeration cycle apparatus according to the fifth aspect includes the turbomachine according to the fourth aspect, and the flow path through which the refrigerant having the first pressure flows is the first space. The flow path through which the refrigerant having a second pressure lower than the first pressure flows is connected to the second space. According to the sixth aspect, the refrigerant as the cooling gas can be smoothly introduced into the gap between the rotor and the stator, the first flow path, and the second flow path.

The induction motor according to the seventh aspect of the present disclosure is:
A shaft including a plurality of longitudinally extending ribs;
A rotor having an inner peripheral surface in contact with the plurality of ribs and fixed to the shaft;
A stator disposed around the rotor;
A gap between the rotor and the stator;
A first flow path provided between the rib and the rib provided between the shaft and the rotor and adjacent to each other in the circumferential direction of the shaft;
A second flow path penetrating the rotor from an inner peripheral surface of the rotor toward an outer peripheral surface of the rotor, and communicating the first flow path and the gap in the radial direction of the shaft;
It is equipped with.

  According to the seventh aspect, the same effect as described in the first aspect can be obtained.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

  As shown in FIG. 1, the refrigeration cycle apparatus 100 of the present embodiment includes a main circuit 5, a heat absorption circuit 6 (low pressure side circulation circuit), and a heat radiation circuit 7 (high pressure side circulation circuit). The refrigeration cycle apparatus 100 is an air conditioner dedicated to cooling, for example.

  The main circuit 5 includes an evaporator 2, a compressor 3, a condenser 4, and flow paths 5a to 5d. In the main circuit 5, the evaporator 2, the compressor 3 and the condenser 4 are annularly connected in this order. The flow path 5 a connects the vapor outlet of the evaporator 2 and the suction port of the compressor 3. The flow path 5 c connects the discharge port of the compressor 3 and the steam inlet of the condenser 4. The flow path 5 d connects the liquid outlet of the condenser 4 and the liquid inlet of the evaporator 2.

  In the evaporator 2, the refrigerant evaporates and refrigerant vapor (gas phase refrigerant) is generated. The refrigerant vapor generated in the evaporator 2 is sucked into the compressor 3 and compressed. The refrigerant vapor compressed by the compressor 3 is supplied to the condenser 4. In the condenser 4, the refrigerant vapor is cooled to produce a refrigerant liquid (liquid phase refrigerant). The refrigerant liquid is returned from the condenser 4 to the evaporator 2. Each of the flow paths 5a to 5d is constituted by a pipe.

  The refrigeration cycle apparatus 100 contains, for example, a substance whose saturation vapor pressure at normal temperature (Japanese Industrial Standard: 20 ° C. ± 15 ° C./JIS Z8703) is negative (absolute pressure lower than atmospheric pressure) as a main component. Refrigerant is filled. Examples of such a refrigerant include a refrigerant containing water, alcohol, or ether as a main component. During operation of the refrigeration cycle apparatus 100, the pressure inside the refrigeration cycle apparatus 100 is lower than atmospheric pressure, for example. The “main component” means a component that is contained most in mass ratio.

  In the refrigeration cycle apparatus 100, the heat absorption circuit 6 is connected to the evaporator 2. The heat dissipation circuit 7 is connected to the condenser 4.

  The heat absorption circuit 6 includes a pump 61, a heat exchanger 62, and flow paths 6a to 6c. The upstream end (one end of the flow path 6 a) of the heat absorption circuit 6 is connected to the bottom of the evaporator 2. The downstream end of the heat absorption circuit 6 (one end of the flow path 6 c) is connected to the upper part of the evaporator 2. The evaporator 2, the pump 61, and the heat exchanger 62 are connected in this order by the flow paths 6a to 6c. Specifically, the flow path 6 a connects the liquid outlet of the evaporator 2 and the inlet of the pump 61. The flow path 6 b connects the outlet of the pump 61 and the inlet of the heat exchanger 62. The flow path 6 c connects the outlet of the heat exchanger 62 and the other liquid inlet of the evaporator 2. Each flow path 6a-6c is comprised by piping. Due to the action of the pump 61, the refrigerant liquid stored in the evaporator 2 is supplied to the heat exchanger 62. The refrigerant liquid absorbs heat in the heat exchanger 62 and is returned to the evaporator 2.

  The heat exchanger 62 is a heat exchanger such as a shell tube heat exchanger or a fin tube heat exchanger. When the refrigeration cycle apparatus 100 is an air conditioner that cools a room, the heat exchanger 62 is installed indoors. The indoor air is cooled by the refrigerant liquid.

  The heat dissipation circuit 7 includes a pump 71, a heat exchanger 72, and flow paths 7a to 7c. The upstream end of the heat dissipation circuit 7 (one end of the flow path 7 a) is connected to the bottom of the condenser 4. The downstream end of the heat dissipation circuit 7 (one end of the flow path 7 c) is connected to the upper part of the condenser 4. The condenser 4, the pump 71, and the heat exchanger 72 are connected in this order by the flow paths 7a to 7c. Specifically, the flow path 7 a connects the other liquid outlet of the condenser 4 and the inlet of the pump 71. The flow path 7 b connects the outlet of the pump 71 and the inlet of the heat exchanger 72. The flow path 7 c connects the outlet of the heat exchanger 72 and the other steam inlet of the condenser 4. Each flow path 7a-7c is comprised with piping. Due to the action of the pump 71, the refrigerant liquid stored in the condenser 4 is supplied to the heat exchanger 72. The refrigerant liquid is cooled in the heat exchanger 72 and returned to the condenser 4.

  The heat exchanger 72 is a heat exchanger such as a shell tube heat exchanger or a fin tube heat exchanger. When the refrigeration cycle apparatus 100 is an air conditioner that cools indoors, the heat exchanger 72 is installed outdoors. The refrigerant liquid is cooled by the outdoor air.

  The evaporator 2 (low pressure side storage tank) is constituted by, for example, a container having heat insulation and heat resistance. The evaporator 2 stores the refrigerant liquid and evaporates the refrigerant liquid inside. That is, the refrigerant liquid heated by absorbing heat from the external environment boils in the evaporator 2. In the present embodiment, the refrigerant liquid stored in the evaporator 2 is in direct contact with the refrigerant liquid circulating in the heat absorption circuit 6. That is, a part of the refrigerant liquid stored in the evaporator 2 is heated by the heat exchanger 62 and used to heat the saturated refrigerant liquid.

  The heat absorption circuit 6 may be configured so that the refrigerant liquid stored in the evaporator 2 is not mixed with the heat medium circulating in the heat absorption circuit 6. For example, when the evaporator 2 has a shell tube heat exchanger structure, the refrigerant liquid stored in the evaporator 2 can be heated and evaporated by the heat medium circulating in the heat absorption circuit 6. At this time, the heat exchanger 62 heats the heat medium for heating the refrigerant liquid stored in the evaporator 2. The heat medium is a liquid such as water or oil.

  The condenser 4 (high-pressure side storage tank) is constituted by, for example, a container having heat insulating properties and pressure resistance. The condenser 4 condenses the refrigerant vapor and stores the refrigerant liquid generated by condensing the refrigerant vapor. In this actual form, the refrigerant vapor in an overheated state directly condenses with the refrigerant liquid cooled by releasing heat to the external environment. That is, a part of the refrigerant liquid stored in the condenser 4 is cooled by the heat exchanger 72 and used to cool the refrigerant vapor in an overheated state.

  The heat dissipation circuit 7 may be configured so that the refrigerant liquid stored in the condenser 4 is not mixed with the heat medium circulating in the heat dissipation circuit 7. For example, when the condenser 4 has a shell tube heat exchanger structure, the refrigerant vapor can be cooled and condensed by the heat medium circulating in the heat radiation circuit 7. At this time, the heat exchanger 72 cools the heat medium for cooling the refrigerant vapor. The heat medium is a liquid such as water or oil.

  In the present embodiment, the compressor 3 is a turbo compressor. Specifically, the compressor 3 is a single-shaft two-stage centrifugal compressor. The compressor 3 includes a first impeller 12, a second impeller 13, and a motor 30. The first impeller 12 and the second impeller 13 are fixed to the motor 30. Specifically, the motor 30 has the shaft 10. The first impeller 12 is fixed to one end of the shaft 10 by shrink fitting, for example. The second impeller 13 is fixed to the other end of the shaft 10 by shrink fitting, for example. The 1st impeller 12 and the 2nd impeller 13 rotate with the shaft 10, and give a kinetic energy to a refrigerant | coolant. The shaft 10 is supported by a first bearing 20 and a second bearing 21.

  The first impeller 12 constitutes a first compression unit of the compressor 3. The second impeller 13 constitutes a second compression unit of the compressor 3. The flow path 5b of the main circuit 5 connects the discharge port of the first compression unit and the suction port of the second compression unit. The refrigerant sucked into the compressor 3 is compressed by the first compression unit. The compressed refrigerant is supplied to the second compression unit through the flow path 5b and further compressed.

  The first bearing 20 and the second bearing 21 are, for example, sliding bearings that support the shaft 10 in the radial direction. A first bearing 20 is disposed at one end of the shaft 10, and a second bearing 21 is disposed at the other end of the shaft 10. The first bearing 20 is a component that surrounds the shaft 10 with a lubricant interposed between the inner peripheral surface of the first bearing 20 and the outer peripheral surface of the shaft 10. The width of the gap between the inner peripheral surface of the first bearing 20 and the outer peripheral surface of the shaft 10 (radial width) is such that sufficient fluid lubrication is achieved by the lubricant during operation of the compressor 3. It has been established. These also apply to the second bearing 21.

  The refrigeration cycle apparatus 100 includes a cooling gas passage 8. The cooling gas passage 8 is a passage for supplying the cooling gas to the motor 30 and discharging the cooling gas from the motor 30. In the present embodiment, the refrigerant of the refrigeration cycle apparatus 100 is used as the cooling gas. Specifically, the cooling gas path 8 includes a high pressure portion 8a and a low pressure portion 8b. The high pressure portion 8 a has one end connected to the condenser 4 and the other end connected to the motor 30. One end of the high-pressure portion 8 a opens toward the space above the condenser 4, that is, the space above the liquid level of the refrigerant liquid stored in the condenser 4. The other end of the high-pressure portion 8 a opens toward the motor chamber 33 that is the internal space of the motor 30. Thereby, the refrigerant gas can be easily guided from the condenser 4 to the motor 30 through the high-pressure portion 8a. The low-pressure portion 8 b includes one end connected to the motor 30 and the other end connected to the evaporator 2. One end of the low-pressure portion 8 b opens toward the space above the evaporator 2, that is, the space above the liquid level of the refrigerant liquid stored in the evaporator 2. The other end of the low pressure portion 8 b opens toward the motor chamber 33. Thereby, the refrigerant gas can be easily guided from the motor 30 to the evaporator 2 through the low pressure portion 8b.

  As shown in FIG. 2, the compressor 3 further includes a casing 50. The first impeller 12, the second impeller 13, and the motor 30 are stored in the casing 50. Inside the casing 50, the motor chamber 33 is located between the first impeller 12 and the second impeller 13. The casing 50 includes a first suction space 14a, a second suction space 14b, a first discharge space 16a, and a second discharge space 16b.

  The first suction space 14 a constitutes the suction port of the first compression unit including the first impeller 12. The flow path 5a of the main circuit 5 is connected to the first suction space 14a. The refrigerant is guided to the first impeller 12 through the first suction space 14a. The second suction space 14 b constitutes a suction port of the second compression unit including the second impeller 13. The flow path 5b of the main circuit 5 is connected to the second suction space 14b. The refrigerant is guided to the second impeller 13 through the second suction space 14b. The first suction space 14 a and the second suction space 14 b are spaces surrounded by the inner peripheral surface of the casing 50 and open toward the outside of the compressor 3.

  The first discharge space 16 a constitutes a discharge port of the first compression unit including the first impeller 12. The flow path 5b of the main circuit 5 is connected to the first discharge space 16a. The first discharge space 16a communicates with the second suction space 14b through the flow path 5b. The first discharge space 16 a is a spiral space formed around the first impeller 12. The second discharge space 16 b constitutes a discharge port of the second compression unit including the second impeller 13. The flow path 5c of the main circuit 5 is connected to the second discharge space 16b. The second discharge space 16 b is a spiral space formed around the second impeller 13. The refrigerant compressed by the first impeller 12 is directly guided from the first discharge space 16a to the second suction space 14b through the flow path 5b. When the intermediate cooler is disposed in the flow path 5b, the refrigerant is cooled in the intermediate cooler and then guided to the second suction space 14b.

  The motor 30 includes a rotor 31 and a stator. The casing 50 also serves as the casing of the motor 30. A motor chamber 33 is formed inside the casing 50. Specifically, the internal space of the casing 50 is partitioned by a plurality of wall surfaces, thereby forming a motor chamber 33. A rotor 31 and a stator 33 are disposed in the motor chamber 33. The rotor 31 is fixed to the shaft 10. The stator is fixed to the casing 50. The shaft 10 protrudes from the motor chamber 33.

  Next, the structure of the motor 30 will be described in detail.

  As shown in FIG. 3, in the motor 30, the stator 32 is arranged concentrically around the rotor 31. A gap 37 is formed between the rotor 31 and the stator 32. In the present embodiment, the motor 30 is an induction motor. The rotor 31 and the stator 32 each have a cylindrical shape.

  The stator 32 includes an iron core and a plurality of coils. Each of the plurality of coils is wound around an iron core. The iron core is composed of a plurality of laminated electromagnetic steel plates. The stator 32 is fixed to the inner wall of the motor chamber 33. A voltage having a predetermined frequency is applied to each coil of the stator 32 by an inverter (not shown). As a result, a magnetic field is generated around the stator 32. The magnetic field moves periodically in the rotation direction of the motor 30.

  The rotor 31 includes an iron core 35 and a plurality of conductor bars 34. The iron core 35 is composed of a plurality of laminated electromagnetic steel plates. The rotor 31 has a cylindrical inner peripheral surface 31q and a cylindrical outer peripheral surface 31p. In a cross section perpendicular to the rotation axis of the motor 30, the rotor 31 has a ring shape. The conductor bar 34 is made of a metal material such as aluminum or copper. Each conductor bar 34 is embedded in the iron core 35. The plurality of conductor bars 34 are arranged at equiangular intervals. Cylindrical end rings (not shown in FIG. 3) are respectively attached to both ends of the rotor 31, and a plurality of conductor bars 34 are short-circuited to each other via these end rings. A cage-like electric circuit is formed by the conductor bar 34 and the end ring. The rotor 31 is fixed to the shaft 10 by shrink fitting, and rotates due to electromagnetic interaction between the rotor 31 and the stator 32. Specifically, an induced current flows in the electric circuit of the rotor 31 in response to the magnetic field generated by the stator 32. A magnetic field is generated by the iron core 35, and this magnetic field and the magnetic field of the stator 32 attract each other, and a rotational force of the motor 30 is generated.

  The shaft 10 includes a shaft body 11 and a plurality of ribs 36. The shaft body 11 is a cylindrical portion. The plurality of ribs 36 are linear portions that protrude outward from the shaft body 11 in the radial direction. The plurality of ribs 36 extend in the longitudinal direction of the shaft 10. In a cross section perpendicular to the rotation axis of the motor 30, the plurality of ribs 36 are arranged around the shaft body 11 at equal angular intervals. In the radial direction of the shaft 10, the outer peripheral surface 36 p of the rib 36 is in contact with the inner peripheral surface 31 q of the rotor 31. Thereby, the rotor 31 is fixed to the shaft 10. The plurality of ribs 36 are located between the shaft main body 11 and the rotor 31 and play a role of connecting the rotor 31 and the shaft main body 11.

  In the present embodiment, the plurality of ribs 36 are formed integrally with the shaft body 11. For example, the shaft 10 is obtained by cutting a rod-shaped member. However, the member having the plurality of ribs 36 may be a separate member from the shaft body 11. In this case, a member having a plurality of ribs 36 is fitted to the shaft body 11.

  The motor 30 further includes a plurality of first flow paths 38 and a plurality of second flow paths 39.

  The plurality of first flow paths 38 (axial flow paths) are flow paths provided between the shaft 10 and the rotor 31, and are adjacent to each other in the circumferential direction of the shaft 10. Exists between. The first flow path 38 is surrounded by the shaft body 11, the ribs 36, the ribs 36, and the rotor 31. The first flow path 38 also extends in the longitudinal direction of the shaft 10 in the same manner as the rib 36. The first flow path 38 opens toward the motor chamber 33 at the position of one end surface and the other end surface of the rotor 31. According to such a structure, the first flow path 38 through which the cooling gas can flow while firmly fixing the rotor 31 to the shaft 10 can be formed between the shaft 10 and the rotor 31.

  The plurality of second flow paths 39 (radial flow paths) pass through the rotor 31 from the inner peripheral surface 31q of the rotor 31 toward the outer peripheral surface 31p of the rotor 31, and are second in the radial direction of the shaft 10. One flow path 38 and the gap 37 are communicated. The plurality of second flow paths 39 are provided in the rotor 31 at equal angular intervals. A second flow path 39 communicates with each of the first flow paths 38. The second flow path 39 is provided in the central portion of the rotor 31 in a direction (axial direction) parallel to the rotation axis of the shaft 10. The cooling gas can also flow through the second flow path 39. When the shaft 10 rotates, the cooling gas flows from the first flow path 38 toward the gap 37 through the second flow path 39. In the present embodiment, only one second flow path 39 communicates with one first flow path 38. However, a plurality of second flow paths 39 may communicate with one first flow path 38. The former configuration is advantageous from the viewpoint of the efficiency of the motor 30. The latter configuration is advantageous from the viewpoint of cooling the motor 30. Furthermore, the second flow path 39 may communicate with only a part of the first flow paths 38 selected from the plurality of first flow paths 38. For example, the second flow path 39 may communicate with only one of the pair of first flow paths 38 adjacent to each other in the circumferential direction of the shaft 10.

  According to the present embodiment, the outer peripheral surface 36 p of the rib 36 is in contact with the inner peripheral surface 31 q of the rotor 31, whereby the rotor 31 is fixed to the shaft 10. Since the contact area between the rotor 31 and the shaft 10 is small, the heat of the rotor 31 is not easily transmitted to the shaft 10.

  According to the present embodiment, the length of the second flow path 39 in the radial direction of the shaft 10 can be sufficiently ensured. In this case, since centrifugal force acts on a larger volume of the cooling gas, the pressure at the outlet of the second flow path 39 is increased, and the flow rate of the cooling gas flowing into the gap 37 between the rotor 31 and the stator 32 is increased. To do. Therefore, the amount of heat released from the motor 30 to the cooling gas (refrigerant gas) also increases.

  According to the present embodiment, the first flow path 38 is between the shaft 10 and the rotor 31. In this case, since the vent hole penetrating the rotor 31 in the axial direction can be omitted, saturation of the magnetic flux in the rotor 31 is prevented. As a result, slip loss is reduced and heat generation of the motor 30 is suppressed. Of course, there may be a vent hole penetrating the rotor 31 in the axial direction.

  Due to the combined effects described above, heat transfer from the shaft 10 of the motor 30 to each of the first impeller 12 and the second impeller 13 is suppressed. That is, heat transfer from the motor 30 to the refrigerant (working fluid) is suppressed. As a result, a decrease in compression efficiency and a decrease in lubricity can be suppressed.

  As shown in FIG. 4, each of the plurality of ribs 36 extends spirally in the longitudinal direction of the shaft 10. Specifically, each of the plurality of ribs 36 spirally extends in the longitudinal direction of the shaft 10 at a twist angle θ opposite to the rotational direction D1 of the shaft 10. Similarly, the plurality of first flow paths 38 also extend spirally in the longitudinal direction of the shaft 10 at a twist angle θ opposite to the rotational direction D1 of the shaft 10. According to such a configuration, the cooling gas flows into each of the first flow paths 38 at a turning speed sufficiently slower than the rotation speeds of the shaft 10 and the rotor 31. Thereafter, the rotation speed of the cooling gas is accelerated to the rotation speed of the rotor 31 by the action of the plurality of ribs 36. The plurality of helical ribs 36 accelerates the cooling gas not only in the swiveling direction but also in the axial direction. As a result, the flow rate of the cooling gas in the first flow path 38 increases.

  The spiral first flow path 38 functions as a pump that pumps the cooling gas in the axial direction of the shaft 10. This also increases the flow rate of the cooling gas in the first flow path 38. The surface area of the helical rib 36 is larger than that of the straight rib. Therefore, the helical rib 36 improves the cooling performance of the first flow path 38. Further, the spiral rib 36 can be thickened while maintaining the cooling performance of the first flow path 38. In this case, since the rigidity of the shaft 10 is increased, the gap between the first impeller 12 and the casing 50 and the gap between the second impeller 13 and the casing 50 can be reduced. By narrowing these gaps, the leakage flow of the refrigerant can be reduced, so that the efficiency of the compressor 3 is improved.

  Of course, it is not essential that the plurality of ribs 36 are spiral. The plurality of ribs 36 may extend parallel to the rotation axis of the shaft 10. That is, the rib 36 may be linear.

  In FIG. 4, “the twist angle θ in the direction opposite to the rotational direction D1 of the shaft 10” is an angle defined by the following method. First, the end of the rib 36 on the upstream side in the flow direction of the cooling gas in the first flow path 38 is defined as a reference position P. A line segment L1 is defined that starts from the reference position P and is parallel to the cooling gas flow direction in the motor chamber 33 (the cooling gas flow direction in the gap 37). In the developed plan view of the shaft 10, the angle formed by the line segment L 1 and the center line of the rib 36 can be defined as “twist angle θ”. When the rib 36 extends from the reference position P in a direction opposite to the rotation direction D1 of the shaft 10, the twist angle θ may be a twist angle opposite to the rotation direction D1 of the shaft 10.

  As shown in FIG. 5, the motor chamber 33 that is an internal space of the casing 50 includes a first space 43 and a second space 44. A gap 37 between the rotor 31 and the stator 32 is also a space included in the motor chamber 33. The first space 43 is adjacent to one end of the rotor 31 in the longitudinal direction of the shaft 10. The second space 44 is adjacent to the other end of the rotor 31 in the longitudinal direction of the shaft 10. The plurality of first flow paths 38 are open to the first space 43 and the second space 44, respectively. According to such a structure, the cooling gas is smoothly introduced into the gap 37 and the first flow path 38.

  According to the present embodiment, the refrigerant of the refrigeration cycle apparatus 100 is used as the cooling gas for the motor 30. Therefore, no special seal structure is required.

  A high pressure portion 8 a of the cooling gas passage 8 is connected to the first space 43. As described with reference to FIG. 1, the high-pressure portion 8 a is connected to the condenser 4. A refrigerant having a relatively high first pressure flows through the high-pressure portion 8a. A low pressure portion 8 b of the cooling gas path 8 is connected to the second space 44. The low pressure portion 8 b is connected to the evaporator 2. In the low pressure portion 8b, a refrigerant having a second pressure lower than the first pressure flows. According to such a configuration, the refrigerant as the cooling gas can be smoothly introduced into the gap 37, the first flow path 38, and the second flow path 39.

  In FIG. 5, the alternate long and short dash line indicates the flow of the refrigerant gas. The refrigerant gas flows through the cooling gas path 8 due to the pressure difference between the condenser 4 and the evaporator 2. Next, the refrigerant gas moves from the condenser 4 to the first space 43 of the motor chamber 33 through the high-pressure portion 8 a of the cooling gas passage 8. Next, the refrigerant gas flows from the first space 43 to the second space 44 through the gap 37, the first flow path 38 and the second flow path 39. Finally, the refrigerant gas moves from the second space 44 of the motor chamber 33 to the evaporator 2 through the low pressure portion 8 b of the cooling gas passage 8.

  In the motor chamber 33, the refrigerant gas cools the rotor 31 and the stator 32 when flowing through the gap 37. Further, when the refrigerant gas flows through the first flow path 38, the shaft 10 is cooled, and further, the rotor 31 is cooled from the inside of the rotor 31. The refrigerant gas flows into the first flow path 38 due to the pressure difference between the first space 43 and the second space 44. The flow of the refrigerant gas branches from the first flow path 38 to the second flow path 39 by centrifugal force, and the refrigerant gas is pumped toward the gap 37. As a result, the flow rate of the refrigerant gas in the gap 37 increases. The central portion of the rotor 31 is a portion that has the highest temperature in the rotor 31. Similarly, the center portion of the stator 32 is a portion having the highest temperature in the stator 32. According to the 2nd flow path 39, those center parts can be cooled especially efficiently.

  Hereinafter, some modified examples of the refrigeration cycle apparatus 100 and the motor 30 will be described.

  The turbo compressor according to the present disclosure is not limited to the centrifugal compressor, and may be another turbo compressor such as an axial flow compressor or a mixed flow compressor. Centrifugal compressors are suitable for applications that require a high compression ratio with a small number of stages. An axial flow compressor or a mixed flow compressor is suitable for an application that needs to compress a large flow rate of working fluid.

  According to this embodiment, in the axial direction of the shaft 10, the motor 30, the impeller 12 (or 13), and the bearing 20 (or 21) are fixed to the shaft 10 in this order. However, the position of the impeller 12 (or 13) and the position of the bearing 20 (or 21) may be interchanged. Further, in the axial direction of the shaft 10, the motor 30, the first bearing 20, the impeller 12, and the second bearing 21 may be fixed to the shaft 10 in this order. Further, the impeller and the bearing may be disposed only on one side of the motor 30. The number and arrangement of the impellers are not particularly limited. The number and arrangement of the bearings are not particularly limited.

  The 1st bearing 20 and the 2nd bearing 21 are not limited to a slide bearing, Other bearings, such as a ball bearing and a roller bearing, may be sufficient.

  In the present embodiment, the width of the rib 36 on the side in contact with the shaft body 11 (the width in the circumferential direction of the shaft 10) is approximately equal to the width of the rib 36 on the side in contact with the rotor 31. However, in the cross section perpendicular to the axial direction of the shaft 10, the shaft 10 may have a cross-sectional shape of a gear. That is, the width of the rib 36 on the side in contact with the shaft body 11 may be larger than the width of the rib 36 on the side in contact with the rotor 31. According to such a structure, the contact area between the rotor 31 and the shaft 10 is reduced, and heat transfer from the rotor 31 to the shaft 10 can be further suppressed. Further, the rigidity of the rib 36 due to the increase in thickness is also improved.

  The refrigeration cycle apparatus 100 may further include a cooler for cooling the internal space of the condenser 4. The cooler can be constituted by, for example, a pipe or a Peltier element for flowing a cooling heat medium. When a condenser is arranged inside the condenser 4, the outer peripheral surface of the condenser 4 is covered with a heat insulating material in order to prevent a cooling gas such as a refrigerant gas from absorbing the heat around the condenser 4. It is desirable that the condenser 4 has a heat insulating structure. Thereby, cooling gas can be cooled reliably.

  The refrigeration cycle apparatus 100 may further include an intercooler disposed in the flow path 5b. The intercooler includes, for example, a shell tube heat exchanger. A cooling heat medium (liquid such as water) flows through the tube of the shell tube heat exchanger, and refrigerant vapor flows inside the shell.

  The high pressure portion 8a of the cooling gas passage 8 may be branched from the outlet of the intermediate cooler described above. When the refrigerant gas compressed by the first impeller 12 is cooled by the intermediate cooler, the temperature of the refrigerant gas is relatively low at the outlet of the intermediate cooler. Therefore, the refrigerant gas present at the outlet of the intermediate cooler is suitable for cooling the motor 30. When water is used as the refrigerant of the refrigeration cycle apparatus 100, in the condenser 4, the refrigerant gas has a temperature of 35 ° C. and a pressure of 6 kPa, for example. At the outlet of the intercooler, the refrigerant gas has, for example, a temperature of 20 ° C. and a pressure of 3 kPa.

  The refrigeration cycle apparatus 100 may be an air conditioner capable of switching between cooling and heating. In this case, each of the indoor heat exchanger arranged indoors and the outdoor heat exchanger arranged outdoor is connected to each of the evaporator 2 and the condenser 4 via a four-way valve. During the cooling operation, the indoor heat exchanger functions as a heat exchanger 62 for heat absorption, and the outdoor heat exchanger functions as a heat exchanger 72 for heat dissipation. During the heating operation, the indoor heat exchanger functions as a heat exchanger 72 for heat dissipation, and the outdoor heat exchanger functions as a heat exchanger 62 for heat absorption.

  The refrigeration cycle apparatus 100 may be a chiller. The heat exchanger 62 may cool a gas or liquid other than air by absorbing heat of the refrigerant. The heat exchanger 72 may heat a gas or liquid other than air by radiating the refrigerant. The heat exchanger 62 and the heat exchanger 72 are not particularly limited as long as they are indirect heat exchangers.

  The technology disclosed herein is particularly useful for turbomachines that draw and compress working fluid. Specifically, the technology disclosed in this specification is useful for home or commercial air conditioners, chillers, heat pump water heaters, and the like. The technology disclosed in this specification can also be applied to a large-scale refrigeration cycle apparatus such as an industrial ice making apparatus or a refrigeration apparatus. Furthermore, the technique disclosed in the present specification is also useful for an air compression apparatus that can be used in a plant, a large ship, and the like. The air compressor may be used as a power source for a pneumatic machine or as a source of compressed air for an air cleaner for a clean room. The technology disclosed in this specification can also be applied to a generator of an expansion turbine that expands a working fluid.

2 Evaporator (low pressure side storage tank)
3 Compressor 4 Condenser (High-pressure side storage tank)
DESCRIPTION OF SYMBOLS 10 Shaft 12 1st impeller 13 2nd impeller 30 Motor 31 Rotor 32 Stator 33 Motor chamber 36 Rib 37 Clearance 38 1st flow path 39 2nd flow path 43 1st space 44 2nd space 50 Casing 100 Refrigeration cycle apparatus

Claims (6)

A motor,
An impeller fixed to the motor;
A turbomachine comprising:
The motor is
A shaft including a plurality of longitudinally extending ribs;
A rotor having an inner peripheral surface in contact with the plurality of ribs and fixed to the shaft;
A stator disposed around the rotor;
A gap between the rotor and the stator;
A first flow path provided between the rib and the rib provided between the shaft and the rotor and adjacent to each other in the circumferential direction of the shaft;
A second flow path penetrating the rotor from an inner peripheral surface of the rotor toward an outer peripheral surface of the rotor, and communicating the first flow path and the gap in the radial direction of the shaft;
Having a turbomachine.   The turbo machine according to claim 1, wherein each of the plurality of ribs extends in a spiral shape in the longitudinal direction of the shaft.   The turbo machine according to claim 1, wherein each of the plurality of ribs extends in a spiral shape in the longitudinal direction of the shaft at a twist angle opposite to a rotation direction of the shaft. The motor further includes a casing storing the shaft, the rotor, and the stator,
The casing has, as its internal space, a first space adjacent to one end of the rotor in the longitudinal direction of the shaft and a second space adjacent to the other end of the rotor in the longitudinal direction of the shaft. Including two spaces,
The turbomachine according to any one of claims 1 to 3, wherein the first flow path is opened in each of the first space and the second space. An evaporator for evaporating the refrigerant;
A compressor for compressing the refrigerant vaporized by the evaporator;
A condenser for condensing the refrigerant compressed by the compressor;
With
The compressor includes the turbomachine according to any one of claims 1 to 4,
A refrigeration cycle apparatus in which the refrigerant is used as a cooling gas for the motor. The compressor includes the turbomachine according to claim 4,
A flow path through which the refrigerant having a first pressure flows is connected to the first space;
The refrigeration cycle apparatus according to claim 5, wherein a flow path through which the refrigerant having a second pressure lower than the first pressure flows is connected to the second space.

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