JP6799792B2 - Fluid machinery and refrigeration cycle equipment - Google Patents

Description

The present disclosure relates to fluid machinery and refrigeration cycle equipment.

Conventionally, in a refrigerator in which water is used as a refrigerant, a technique for supplying lubricating water to a bearing of a compressor is known. For example, Patent Document 1 describes the refrigerator 100.

As shown in FIG. 9, the refrigerator 100 includes an evaporator 102, a compressor 104, a condenser 106, a refrigerant gas lead-out line 109, a cooling water line 114, a cooling tower 116, a cooling water pump 118, and the like. It includes a lubricating water pump 111, a lubricating water supply line 132, and a lubricating water discharge line 134. The lubricating water circuit includes a condenser 106, a cooling water line 114, a cooling tower 116, a cooling water pump 118, a lubricating water pump 111, a lubricating water supply line 132, a compressor 104, and a lubricating water discharge line 134. It is composed of and. The lubricating water supply line 132 is for supplying water as a lubricant to the bearings and the like of the compressor 104, and connects the bearings and the like of the compressor 104 to the downstream portion of the cooling tower 116 in the cooling water line 114. ing. A part of the cooling water returned from the cooling tower 116 to the condenser 106 through the cooling water line 114 is supplied to the compressor 104 as lubricating water through the lubricating water supply line 132.

Further, a technique of supplying a part of liquid refrigerant to a bearing in a turbo compressor in a turbo chiller is also known. For example, Patent Document 2 describes a turbo chiller 300.

As shown in FIG. 10, the turbo chiller 300 includes a turbo compressor 330, a condenser 302, and an evaporator 305. In the turbo compressor 330, the centrifugal impeller 331 is fixed to the output shaft 333 of the inverter motor 332. The output shaft 333 is supported by a radial bearing 339, a radial bearing 340, a thrust bearing 341, and a thrust bearing 342. The saturated liquid refrigerant in the liquid pool 343 formed in the lower part of the evaporator 305 is extracted by the liquid refrigerant pump 344. The saturated liquid refrigerant is pressurized by the liquid refrigerant pump 344 so as to be in an overcooled state, and then supplied to the radial bearing 339, the radial bearing 340, the thrust bearing 341, or the thrust bearing 342 to lubricate them. After lubricating the radial bearing 339, the radial bearing 340, the thrust bearing 341, or the thrust bearing 342, the liquid refrigerant returns to the evaporator 305 due to its own weight and differential pressure.

Japanese Unexamined Patent Publication No. 2011-196185 Japanese Unexamined Patent Publication No. 10-132395

According to the techniques described in Patent Documents 1 and 2, the state of the lubricating water or the liquid refrigerant supplied to the bearing of the compressor is not always the desired state. Therefore, in the present disclosure, when lubricating a bearing in a compressor with a lubricating liquid containing the same type of substance as the main component of the refrigerant as the main component, the lubricating liquid is supplied to the bearing in a desirable state. Providing advantageous technology.

This disclosure is
A first compressor having a first suction port and a first discharge port, a second compressor having a second suction port and a second discharge port, and at least one of the first compressor and the second compressor. A multi-stage compressor including a bearing that supports a shaft for driving a compressor, wherein a gaseous compressor is sucked from the first suction port, compressed, and then discharged from the first discharge port. In addition, the multi-stage compressor in which the gaseous refrigerant discharged from the first discharge port of the second compressor is sucked from the second suction port, compressed, and then discharged from the second discharge port.
A pressure vessel that stores a lubricating liquid that contains the same type of substance as the main component of the refrigerant as the main component,
A first supply path that connects the pressure vessel and the bearing and supplies the lubricating liquid stored in the pressure vessel to the bearing.
A pump located on the first supply path and delivering the lubricating fluid towards the bearings,
A first return path that connects the bearing and the pressure vessel and returns the lubricating liquid that has passed through the bearing to the pressure vessel.
An intermediate pressure maintained at a pressure higher than the pressure of the gaseous refrigerant at the first suction port and lower than the pressure of the gaseous refrigerant at the second discharge port during the operating period of the multi-stage compressor. With space,
The internal space of the pressure vessel forms a part of the intermediate pressure space.
Provide a fluid machine.

According to the above-mentioned fluid machine, the lubricating liquid stored in the pressure vessel and containing the same type of substance as the main component of the refrigerant as the main component is likely to be supplied to the bearing of the multi-stage compressor in a desirable state.

FIG. 1 is a block diagram showing an example of the fluid machine of the present disclosure. FIG. 2 is a configuration diagram showing a modified example of the fluid machine shown in FIG. FIG. 3 is a configuration diagram showing another modification of the fluid machine shown in FIG. FIG. 4 is a configuration diagram showing still another modification of the fluid machine shown in FIG. FIG. 5 is a configuration diagram showing still another modification of the fluid machine shown in FIG. FIG. 6 is a block diagram showing another example of the fluid machine of the present disclosure. FIG. 7 is a configuration diagram showing an example of the refrigeration cycle apparatus of the present disclosure. FIG. 8 is a configuration diagram showing another example of the refrigeration cycle apparatus of the present disclosure. FIG. 9 is a configuration diagram showing a conventional refrigerator. FIG. 10 is a configuration diagram showing a conventional turbo chiller.

<Knowledge based on the study by the present inventors>
The present inventors have considered using a liquid refrigerant of a refrigeration cycle device as a lubricating liquid for lubricating a bearing of a multi-stage compressor in a refrigeration cycle device. In this case, for example, it is conceivable to use a part of the liquid refrigerant from the evaporator or the condenser as a lubricating liquid for lubricating the bearing of the multi-stage compressor. However, the present inventors have newly found that the liquid refrigerant taken out from the evaporator or the condenser is not always in a desirable state as a lubricating liquid. For example, a liquid refrigerant taken out from an evaporator as a lubricating liquid has a saturation temperature with respect to a low pressure which is a pressure in an evaporator or a temperature near a saturation temperature with respect to a low pressure which is a pressure in an evaporator. In this case, the temperature of the lubricating liquid is low, and condensation or dew condensation of the gaseous refrigerant is likely to occur in the multi-stage compressor. On the other hand, for example, the liquid refrigerant taken out from the condenser as a lubricating liquid has a saturation temperature with respect to a high pressure which is the pressure in the condenser or a temperature near the saturation temperature with respect to the high pressure which is the pressure in the condenser. In this case, the temperature of the lubricating liquid may be high and the bearing may not be cooled properly.

Therefore, the present inventors have repeatedly studied day and night on a technique capable of supplying a lubricating liquid containing the same type of substance as the main component of the refrigerant as the main component to the bearing of the multi-stage compressor in a desirable state. As a result of the study, the present inventors have found that the lubricating liquid can be supplied to the bearing in a desired state by keeping the internal space of the pressure vessel for storing the lubricating liquid at a predetermined pressure separately from the evaporator and the condenser. It was. The present inventors have devised the fluid machine of the present disclosure based on such new findings. In addition, in this specification, a "principal component" means a component contained most in mass basis.

The first aspect of the present disclosure is
A first compressor having a first suction port and a first discharge port, a second compressor having a second suction port and a second discharge port, and at least one of the first compressor and the second compressor. A multi-stage compressor including a bearing that supports a shaft for driving a compressor, wherein a gaseous compressor is sucked from the first suction port, compressed, and then discharged from the first discharge port. In addition, the multi-stage compressor in which the gaseous refrigerant discharged from the first discharge port of the second compressor is sucked from the second suction port, compressed, and then discharged from the second discharge port.
A pressure vessel that stores a lubricating liquid that contains the same type of substance as the main component of the refrigerant as the main component,
A first supply path that connects the pressure vessel and the bearing and supplies the lubricating liquid stored in the pressure vessel to the bearing.
A pump located on the first supply path and delivering the lubricating fluid towards the bearings,
A first return path that connects the bearing and the pressure vessel and returns the lubricating liquid that has passed through the bearing to the pressure vessel.
An intermediate pressure maintained at a pressure higher than the pressure of the gaseous refrigerant at the first suction port and lower than the pressure of the gaseous refrigerant at the second discharge port during the operating period of the multi-stage compressor. With space,
The internal space of the pressure vessel forms a part of the intermediate pressure space.
Provide a fluid machine.

According to the first aspect, the internal space of the pressure vessel in which the lubricating liquid containing the same type of substance as the main component of the refrigerant as the main component is stored forms a part of the intermediate pressure space. Therefore, the lubricating liquid stored in the pressure vessel tends to reach the saturation temperature at the intermediate pressure or a temperature near the saturation temperature. As a result, the lubricating liquid stored in the pressure vessel tends to have a desired temperature for lubricating the bearings, and the lubricating liquid tends to be supplied to the bearings of the multi-stage compressor in a desirable state. Here, the intermediate pressure is a pressure that is higher than the pressure of the gaseous refrigerant at the first suction port and lower than the pressure of the gaseous refrigerant at the second discharge port during the operating period of the multi-stage compressor.

In the second aspect of the present disclosure, in addition to the first aspect, the intermediate pressure space passes through the first discharge port and the second suction port during the operating period of the multi-stage compressor. Provided is a fluid machine filled with the gaseous refrigerant which is not. According to the second aspect, a gaseous refrigerant that has passed through the first discharge port and has not passed through the second suction port can be used in order to keep the internal space of the pressure vessel at a desired pressure. In addition, the pressure in the internal space of the pressure vessel in which the lubricating liquid is stored is likely to be maintained at a more desirable pressure, and the lubricating liquid can be more reliably supplied to the bearing in a desired state.

In the third aspect of the present disclosure, in addition to the first aspect or the second aspect, the intermediate pressure space connects the first discharge port and the pressure vessel, and is discharged from the first discharge port. To connect the pressure vessel and the second suction port to a second supply path for guiding the gaseous refrigerant to the internal space of the pressure vessel, and to guide the gaseous refrigerant to the second compressor. Provide fluid machinery, including with a third supply channel of. According to the third aspect, the gaseous refrigerant discharged from the first discharge port passes through the second supply passage, the internal space of the pressure vessel, and the third supply passage and is guided to the second compressor. In this way, the internal space of the pressure vessel can be used as a part of the flow path of the gaseous refrigerant. In addition, the gas generated by vaporization from the lubricating liquid due to the loss in the bearing is guided to the second compressor through the third supply path. Therefore, the internal space of the pressure vessel is maintained at a desired pressure. In addition, it is possible to prevent the temperature of the lubricating liquid from continuing to rise.

In the fourth aspect of the present disclosure, in addition to the first aspect or the second aspect, the intermediate pressure space connects the first discharge port and the second suction port, and the gaseous refrigerant is used as the first aspect. (Ii) The fourth supply path for guiding to the compressor, the pressure vessel, and the confluence point on the fourth supply path are connected, and the gas generated by vaporizing from the lubricating fluid is transferred to the second compressor. A fluid machine is provided, including a fifth supply path for guiding. According to the fourth aspect, since the internal space of the pressure vessel is communicated by the fourth supply passage and the fifth supply passage, the internal space of the pressure vessel is maintained at the intermediate pressure, and the internal space of the pressure vessel is the intermediate pressure space. Make a part. In addition, the gas generated by vaporization from the lubricating liquid due to the loss in the bearing is guided to the second compressor through the fifth supply path, so that the internal space of the pressure vessel is maintained at a desired pressure. In addition, it is possible to prevent the temperature of the lubricating liquid from continuing to rise.

A fifth aspect of the present disclosure is, in addition to any one of the first to fourth aspects, a branch point located between the outlet of the pump and the bearing on the first supply path and the pressure vessel. Provided is a fluid machine which is connected by bypassing the bearing and further provided with a second return path for returning a part of the lubricating liquid in the first supply path to the pressure vessel. According to the fifth aspect, the lubricating liquid returned to the pressure vessel through the second return path can be brought into contact with the gaseous refrigerant in the pressure vessel. As a result, the gaseous refrigerant is cooled and the lubricating fluid stored in the pressure vessel is likely to have the desired temperature to more reliably lubricate the bearings.

A sixth aspect of the present disclosure provides a fluid machine, in addition to the fifth aspect, further comprising a first filter arranged on the first supply path to reduce the amount of impurities contained in the lubricating fluid. According to the sixth aspect, the amount of impurities contained in the lubricating liquid can be reduced by the first filter.

A seventh aspect of the present disclosure, in addition to the sixth aspect, provides a fluid machine in which the first filter is located between the outlet of the pump and the branch point on the first supply path. According to the seventh aspect, the amount of impurities in the lubricating liquid flowing through the second return path and the lubricating liquid supplied to the bearing can be reduced without requiring a filter other than the first filter. Therefore, the fluid machine can be simplified and the manufacturing cost can be reduced.

An eighth aspect of the present disclosure, in addition to the sixth aspect, provides a fluid machine in which the first filter is located between the branch point and the bearing on the first supply path. According to the eighth aspect, the amount of impurities in the lubricating liquid supplied to the bearing can be reduced.

A ninth aspect of the present disclosure, in addition to the eighth aspect, is arranged between the outlet of the pump and the branch point on the first supply path to reduce the amount of impurities contained in the lubricating fluid. Provided is a fluid machine further equipped with a filter. According to the ninth aspect, the amount of impurities in the lubricating liquid flowing through the second return path and the lubricating liquid supplied to the bearing can be reduced by the second filter. In addition, impurities that have passed through the second filter can be captured by the first filter. As a result, the amount of impurities in the lubricating liquid supplied to the bearing can be more reliably reduced. Further, since the impurities trapped in the second filter do not reach the first filter, the first filter is less likely to be clogged.

A tenth aspect of the present disclosure provides a fluid machine, in addition to the eighth aspect, further comprising a second filter arranged on the second return path to reduce the amount of impurities contained in the lubricating fluid. According to the tenth aspect, when the second filter is replaced, the lubricating liquid can be continuously supplied to the bearing without stopping the pump on the first supply path.

The eleventh aspect of the present disclosure provides a fluid machine in which, in addition to any one of the first to tenth aspects, the refrigerant and the lubricating liquid contain water as a main component. According to the eleventh aspect, since the latent heat in the evaporation of water is large, the amount of gas vaporized from the lubricating liquid can be reduced.

The twelfth aspect of the present disclosure is
The fluid machine according to any one of the first to eleventh aspects,
An evaporator that evaporates a liquid refrigerant to generate the gaseous refrigerant, and
A first vapor path that connects the evaporator and the first suction port and guides the gaseous refrigerant to the first compressor, and
A condenser that condenses the gaseous refrigerant discharged from the second discharge port, and
A refrigeration cycle apparatus including a second steam passage that connects the second discharge port and the condenser and guides the refrigerant of the gas discharged from the second discharge port to the condenser. provide.

According to the twelfth aspect, since the fluid machine of any one of the first to eleventh aspects is provided, the bearing of the multi-stage compressor is appropriately made, and the refrigeration cycle apparatus has high reliability.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The following embodiments are merely examples, and the present invention is not limited thereto.

<First Embodiment>
As shown in FIG. 1, the fluid machine 1a includes a multi-stage compressor 6, a pressure vessel 10, a first supply path 11, a pump 12, a first return path 15, and an intermediate pressure space 20. The multi-stage compressor 6 includes a first compressor 6a, a second compressor 6b, and a bearing 7. The fluid machine 1a typically forms part of a refrigeration cycle apparatus. The first compressor 6a has a first suction port 6p and a first discharge port 6q. The first compressor 6a sucks a gaseous refrigerant from the first suction port 6p, compresses it, and then discharges it from the first discharge port 6q. The second compressor 6b has a second suction port 6r and a second discharge port 6s. The second compressor 6b sucks the gaseous refrigerant discharged from the first discharge port 6q from the second suction port 6r, compresses it, and then discharges it from the second discharge port 6s. The bearing 7 supports a shaft 6c that drives at least one of the first compressor 6a and the second compressor 6b. The pressure vessel 10 stores a lubricating liquid containing the same type of substance as the main component of the refrigerant as the main component. The first supply path 11 connects the pressure vessel 10 and the bearing 7, and is a flow path for supplying the lubricating liquid stored in the pressure vessel 10 to the bearing 7. The pump 12 is arranged on the first supply path 11 and sends the lubricating fluid toward the bearing 7. The first return path 15 connects the bearing 7 and the pressure vessel 10, and is a flow path for returning the lubricating liquid that has passed through the bearing 7 to the pressure vessel 10. The intermediate pressure space 20 has a pressure higher than the pressure of the gaseous refrigerant at the first suction port 6p and lower than the pressure of the gaseous refrigerant at the second discharge port 6s during the operation period of the multi-stage compressor 6 (intermediate). Pressure) is maintained. The internal space of the pressure vessel 10 forms a part of the intermediate pressure space 20.

The internal space of the pressure vessel 10 is maintained at a desired pressure by a gaseous refrigerant having an intermediate pressure, and the lubricating liquid is easily maintained at a saturation temperature at the intermediate pressure or a temperature near the saturation temperature. Therefore, the lubricating liquid has a desirable temperature for lubricating the bearing 7. As a result, the lubricating liquid is likely to be supplied to the bearing 7 of the multi-stage compressor 6 in a desirable state. As a result, in the multi-stage compressor 6, unstable vibration such as whirl vibration that occurs when the bearing 7 is too cold to condense the gaseous refrigerant or the occurrence of dew condensation can be prevented and the bearing 7 is insufficiently cooled. Can be suppressed.

The intermediate pressure space 20 is not particularly limited as long as it is a space filled with an intermediate pressure gaseous refrigerant. For example, the intermediate pressure space 20 is filled with a gaseous refrigerant that has passed through the first discharge port 6q and has not passed through the second suction port 6r during the operating period of the multi-stage compressor 6. In this case, in order to keep the internal space of the pressure vessel 10 at a desired pressure, a gaseous refrigerant that has passed through the first discharge port 6q and has not passed through the second suction port 6r can be used. In addition, the pressure in the internal space of the pressure vessel 10 in which the lubricating liquid is stored is likely to be maintained at a more desirable pressure, and the lubricating liquid can be more reliably supplied to the bearing 7 in a desired state.

The intermediate pressure space 20 may include a flow path of the refrigerant between the first discharge port 6q and the second suction port 6r in the flow of the refrigerant in the multi-stage compressor 6. Further, the intermediate pressure space 20 may include a space in which the gaseous refrigerant that has passed through the first discharge port 6q drifts toward the second suction port 6r without flowing toward the second suction port 6r during the operating period of the multi-stage compressor 6. In some cases, the intermediate pressure space 20 may include a space in which a gaseous refrigerant decompressed to the intermediate pressure floats.

As shown in FIG. 1, in the fluid machine 1a, the intermediate pressure space 20 includes, for example, a second supply path 8a and a third supply path 8b. The second supply path 8a connects the first discharge port 6q and the pressure vessel 10, and is a flow path for guiding the gaseous refrigerant discharged from the first discharge port 6q to the internal space of the pressure vessel 10. .. The third supply path 8b connects the pressure vessel 10 and the second suction port 6r, and is a flow path for guiding the gaseous refrigerant to the second compressor 6b. In this case, the gaseous refrigerant discharged from the first discharge port 6q passes through the second supply path 8a, the internal space of the pressure vessel 10, and the third supply path 8b, and is guided to the second compressor 6b. In this way, the internal space of the pressure vessel 10 can be used as a part of the flow path of the gaseous refrigerant. The lubricating liquid supplied to the bearing 7 is returned to the pressure vessel 10 through the first return path 15 in a state where the enthalpy is increased due to the loss in the bearing 7. As the enthalpy of the lubricating liquid rises, it vaporizes from the lubricating liquid to generate gas. This gas is guided to the second compressor 6b through the third supply path 8b. Therefore, the internal space of the pressure vessel 10 is likely to be maintained at a desired pressure. Further, even if the radiator is not arranged on the first return path 15, it is possible to prevent the temperature of the lubricating liquid stored in the pressure vessel 10 from continuing to rise due to the loss in the bearing 7.

The gaseous refrigerant discharged from the first discharge port 6q passes through the second supply path 8a and is guided to the internal space of the pressure vessel 10. In this case, for example, in the internal space of the pressure vessel 10, the gaseous refrigerant can be cooled by heat exchange between the gaseous refrigerant and the lubricating liquid. Therefore, the cooled gaseous refrigerant can be guided to the second compressor 6b through the third supply path 8b. In this way, the lubricating liquid stored in the pressure vessel 10 can be used for intermediate cooling of the gaseous refrigerant in the multi-stage compressor 6. As a result, the coefficient of performance (COP) of the refrigeration cycle apparatus provided with the fluid machine 1a can be increased. In this way, the pressure vessel 10 may function as an intercooler.

The first compressor 6a and the second compressor 6b may be, for example, a speed type compressor (turbo compressor) or a positive displacement type compressor, respectively. The speed type compressor is a compressor that compresses the refrigerant by giving momentum to the refrigerant, and the positive displacement compressor is a compressor that compresses the refrigerant by changing the volume, such as a screw compressor. The multi-stage compressor 6 includes, for example, a casing, and the first compressor 6a and the second compressor 6b are housed inside the casing. The first compressor 6a and the second compressor 6b may be housed in a single casing or may be housed in separate casings.

When the first compressor 6a and the second compressor 6b are driven by the shaft 6c, the moving parts of the first compressor 6a and the second compressor 6b move in a rotary motion, a linear motion, or a reciprocating motion. The moving parts of the first compressor 6a and the second compressor 6b are, for example, the impeller of a turbo compressor or the rotor of a screw compressor. The shaft 6c is made of, for example, a metal or alloy. For example, the multi-stage compressor 6 includes one shaft 6c. In this case, parts such as the impeller of the turbo compressor or the rotor of the screw compressor of the first compressor 6a and the second compressor 6b are attached to one shaft 6c, and the first compressor is provided by one shaft 6c. 6a and the second compressor 6b are driven. The shaft 6c is connected to, for example, an electric motor (not shown), and moves when the electric motor operates. The multi-stage compressor 6 may include a plurality of shafts 6c. In this case, for example, the moving parts of the first compressor 6a are attached to any of the plurality of shafts 6c, and the moving parts of the second compressor 6b are attached to another shaft 6c.

The bearing 7 is, for example, a plain bearing or a ball bearing, and is lubricated with a lubricating liquid. The bearing 7 supports the shaft 6c in at least one of the radial direction and the thrust direction.

The pressure vessel 10 is a pressure-resistant container made of a metal material such as steel, and the internal space of the pressure vessel 10 is sealed with respect to the external space of the pressure vessel 10 by welding or a sealing material. As a result, leakage of the lubricating liquid in the internal space of the pressure vessel 10 and inflow of external gas into the internal space of the pressure vessel 10 are prevented.

The pump 12 may be, for example, a positive displacement pump or a speed pump. The positive displacement pump is a pump that boosts the liquid refrigerant by changing the volume, and the speed pump is a pump that boosts the liquid refrigerant by applying momentum to the refrigerant. The pump 12 may include a mechanism for changing the rotation speed of the pump 12 such as a motor driven by an inverter. The discharge pressure of the pump 12 is not particularly limited, but is, for example, 100 to 1000 kPa. The pump 12 may be connected to the controller by wire or wirelessly so as to be able to receive a control signal from the controller, for example. In this case, the pump 12 operates according to the control signal from the controller.

At least a part of each of the first supply path 11, the first return path 15, the second supply path 8a, and the third supply path 8b is composed of a pipe made of a metal material such as steel, for example. In this case, the inside of the pipe is sealed to the outside space of the pipe by welding or a sealing material. This prevents leakage of the lubricating liquid flowing through the first supply path 11 and the first return path 15 and prevention of external gas from flowing into the first supply path 11 and the first return path 15. Further, the leakage of the refrigerant flowing through the second supply path 8a and the third supply path 8b and the inflow of the external gas into the second supply path 8a and the third supply path 8b are prevented.

The refrigerant is not particularly limited, but is, for example, a refrigerant (low pressure refrigerant) having a relatively low saturated vapor pressure of 50 kPaA or less at room temperature. The main components of such a refrigerant are, for example, hydrofluoroolefin (HFO) -based substances such as R-1233zd and R-1234ze or water.

The refrigerant and lubricating liquid preferably contain water as a main component. Since the latent heat in the evaporation of water is large, even if the lubricating liquid is vaporized due to the loss in the bearing 7 or the contact of the gas with the refrigerant, the amount of gas generated by the vaporization of the lubricating liquid is small. Therefore, the amount of the gaseous refrigerant guided to the second compressor 6b through the third supply path 8b is suppressed, and the work to be done by the second compressor 6b can be reduced. In addition, the temperature of the gaseous refrigerant sucked into the second compressor 6b is guided to the internal space of the pressure vessel 10 through the second supply passage 8a so that the temperature becomes the saturation temperature at the intermediate pressure or a temperature near the saturation temperature. It is also possible to cool the gaseous refrigerant.

(Modification example)
The fluid machine 1a can be changed from various viewpoints. The fluid machine 1a may further include a filter on the first supply path 11 that reduces the amount of impurities contained in the lubricating liquid. The filter is composed of, for example, a sintered metal filter or a metal mesh. Further, the hydraulic machine 1a may be modified as shown in FIGS. 2 to 5 such as the hydraulic machine 1b, the hydraulic machine 1c, the hydraulic machine 1d, or the fluid machine 1e.

Each of the fluid machine 1b, the hydraulic machine 1c, the hydraulic machine 1d, and the fluid machine 1e is configured in the same manner as the fluid machine 1a, unless otherwise specified. The components of the fluid machine 1b, the fluid machine 1c, the fluid machine 1d, and the fluid machine 1e that are the same as or correspond to the components of the fluid machine 1a are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIGS. 2 to 5, each of the fluid machine 1b, the fluid machine 1c, the fluid machine 1d, and the fluid machine 1e further includes a second return path 16. The second return path 16 connects the branch point B located between the outlet of the pump 12 on the first supply path 11 and the bearing 7 and the pressure vessel 10 by bypassing the bearing 7. This is a flow path for returning a part of the lubricating liquid in the passage 11 to the pressure vessel 10. Therefore, a part of the lubricating liquid flowing through the first supply path 11 passes through the second return path 16 without passing through the bearing 7 and is returned to the internal space of the pressure vessel 10. This allows the lubricating liquid to come into contact with the gaseous refrigerant. The outlet of the second return path 16 is typically in contact with the intermediate pressure space 20 of the internal space of the pressure vessel 10.

At least a part of the second return path 16 is composed of a pipe made of a metal material such as steel. In this case, the inside of the pipe is sealed to the outside space of the pipe by welding or a sealing material. This prevents the lubricating liquid flowing through the second return path 16 from leaking and the external gas from flowing into the second return path 16.

Each of the fluid machine 1b, the fluid machine 1c, the fluid machine 1d, and the fluid machine 1e further comprises, for example, a first filter 18a. The first filter 18a is a filter arranged on the first supply path 11 to reduce the amount of impurities contained in the lubricating liquid. The amount of impurities contained in the lubricating liquid to be supplied to the bearing 7 by the first filter 18a can be reduced.

The first filter 18a is composed of, for example, a sintered metal filter or a metal mesh, and can capture impurities of 7 μm or more.

As shown in FIG. 2, in the fluid machine 1b, the first filter 18a is arranged between the outlet of the pump 12 on the first supply path 11 and the branch point B. According to the fluid machine 1b, the amount of impurities in the lubricating liquid flowing through the second return path 16 and the lubricating liquid supplied to the bearing 7 can be reduced without requiring a filter other than the first filter 18a. Therefore, the fluid machine 1b can be simplified, and the manufacturing cost of the fluid machine 1b can be easily reduced. In this case, the outlet of the second return path 16 may be defined by a nozzle. In this case, the lubricating liquid flowing out from the outlet of the second return path 16 can be miniaturized. In addition, the first filter 18a is less likely to clog the nozzles that define the outlet of the second return path 16.

As shown in FIGS. 3 to 5, in the fluid machine 1c, the fluid machine 1d, and the fluid machine 1e, the first filter 18a is arranged between the branch point B on the first supply path 11 and the bearing 7. .. Even in this case, the amount of impurities in the lubricating liquid supplied to the bearing 7 can be reduced.

In the fluid machine 1c, only the first filter 18a is arranged on the first supply path 11 as a filter for reducing the amount of impurities contained in the lubricating liquid. In this case, it is desirable that the outlet of the second return path 16 is not defined by the nozzle. This is because impurities may pass through the second return path 16.

As shown in FIG. 4, the fluid machine 1d further includes a second filter 18b. The second filter 18b is a filter that is arranged between the outlet of the pump 12 on the first supply path 11 and the branch point B to reduce the amount of impurities contained in the lubricating liquid. In this case, the amount of impurities in the lubricating liquid flowing through the second return path 16 and the lubricating liquid supplied to the bearing 7 can be reduced by the second filter 18b. In addition, impurities that have passed through the second filter 18b can be captured by the first filter 18a. As a result, the amount of impurities in the lubricating liquid supplied to the bearing 7 can be more reliably reduced. According to the fluid machine 1d, the impurities trapped by the second filter 18b do not reach the first filter 18a, so that the first filter 18a is less likely to be clogged.

As shown in FIG. 5, the fluid machine 1e further includes a second filter 18b. The second filter 18b is a filter arranged on the second return path 16 to reduce the amount of impurities contained in the lubricating liquid. In this case, when the second filter 18b is replaced, the lubricating liquid can be continuously supplied to the bearing 7 without stopping the pump 12.

In the hydraulic machine 1d and the fluid machine 1e, the second filter 18b is composed of, for example, a sintered metal filter or a metal mesh, and can capture impurities having a size larger than the size of the impurities that can be captured by the first filter 18a. is there. For example, the second filter 18b can capture impurities of 40 μm or more.

In the fluid machine 1d and the fluid machine 1e, the outlet of the second return path 16 is defined by, for example, a nozzle. In this case, the lubricating liquid flowing out from the outlet of the second return path 16 can be miniaturized. In addition, the second filter 18b is less likely to clog the nozzles that define the outlet of the second return path 16.

<Second Embodiment>
Next, the fluid machine 1f according to the second embodiment will be described. The fluid machine 1f is configured in the same manner as the fluid machine 1a, unless otherwise specified. The same components as those of the fluid machine 1a or the corresponding components of the fluid machine 1f are designated by the same reference numerals, and detailed description thereof will be omitted. The description of the first embodiment (including the description of the modification) also applies to the second embodiment as long as there is no technical contradiction.

As shown in FIG. 6, in the fluid machine 1f, the intermediate pressure space 20 includes the fourth supply path 8c and the fifth supply path 9. The fourth supply path 8c connects the first discharge port 6q and the second suction port 6r, and is a flow path for guiding the gaseous refrigerant to the second compressor 6b. The fifth supply passage 9 connects the pressure vessel 10 and the confluence J on the fourth supply passage 8c, and is a flow path for guiding the gas generated by vaporizing from the lubricating liquid to the second compressor 6b. Is.

According to the fluid machine 1f, since the internal space of the pressure vessel 10 is communicated with the fourth supply passage 8c by the fifth supply passage 9, the internal space of the pressure vessel 10 is maintained at an intermediate pressure, and the inside of the pressure vessel 10 is maintained. The space forms part of the intermediate pressure space 20. In addition, the gas generated by vaporization from the lubricating liquid due to the loss in the bearing 7 is guided to the second compressor 6b through the fifth supply path 9, so that the internal space of the pressure vessel 10 is maintained at a desired pressure. Cheap. Further, even if the radiator is not arranged on the first return path 15, it is possible to prevent the temperature of the lubricating liquid stored in the pressure vessel 10 from continuing to rise due to the loss in the bearing 7. As a result, the lubricating liquid can be supplied to the bearing 7 in a desired state.

At least a part of the fourth supply path 8c and the fifth supply path 9 is composed of pipes made of a metal material such as steel. In this case, the inside of the pipe is sealed to the outside space of the pipe by welding or a sealing material. As a result, leakage of gas or gaseous refrigerant generated by vaporization of the lubricating liquid flowing through the fourth supply passage 8c and the fifth supply passage 9 and inflow of external gas into the fourth supply passage 8c and the fifth supply passage 9 are prevented. Will be done. When the first compressor 6a and the second compressor 6b are housed inside a single casing, the piping for forming the fourth supply path 8c is typically located outside the casing. .. However, in some cases, a pipe for forming the fourth supply path 8c may be arranged inside the casing. Further, the space inside the casing may form the entire fourth supply path 8c. In this case, the fifth supply path 9 is composed of, for example, a pipe that opens into the space inside the casing forming the fourth supply path 8c.

<Refrigeration cycle equipment>
As shown in FIG. 7, the refrigeration cycle device 50a includes a fluid machine 1a, an evaporator 2, a first steam passage 5a, a condenser 3, and a second steam passage 5b. The evaporator 2 evaporates the liquid refrigerant to generate a gaseous refrigerant. The first steam passage 5a connects the evaporator 2 and the first suction port 6p, and is a flow path for guiding the gaseous refrigerant to the first compressor 6a. The condenser 3 condenses the gaseous refrigerant discharged from the second discharge port 6s. The second steam passage 5b connects the second discharge port 6s and the condenser 3, and is a flow path for guiding the gaseous refrigerant discharged from the second discharge port 6s to the condenser 3.

The evaporator 2 evaporates the liquid refrigerant by absorbing heat from an external heat source of the refrigeration cycle device 50a. The evaporator 2 is, for example, an indirect heat exchanger such as a shell-and-tube heat exchanger and a plate heat exchanger, or a direct heat exchanger such as a spray heat exchanger and a direct heat exchanger having a filler. is there. The evaporator 2 has, for example, a tank 23, a liquid refrigerant flow path 25, and a pump 27, as shown in FIG. The tank 23 is a container for storing a liquid refrigerant. The tank 23 is made of a metal material such as steel, and the internal space of the tank 23 is sealed to the external space of the tank 23 by welding or a sealing material. This prevents the leakage of the liquid refrigerant in the internal space of the tank 23 and the inflow of the external gas into the internal space of the tank 23. The liquid refrigerant flow path 25 has an inlet and an outlet in contact with the internal space of the tank 23, and is a flow path extending from the inlet to the outlet outside the tank 23. The pump 27 is arranged on the liquid refrigerant flow path 25 and discharges the liquid refrigerant toward the internal space of the tank 23. That is, when the pump 27 operates, a part of the liquid refrigerant stored in the tank 23 is extracted and returns to the inside of the tank 23 through the liquid refrigerant flow path 25. In the evaporator 2, the liquid refrigerant flow path 25 and the pump 27 may be omitted in some cases.

At least a part of each of the first steam passage 5a and the second steam passage 5b is composed of pipes made of a metal material such as steel. The inside of the pipe is sealed to the outside space of the pipe by welding or a sealing material. This prevents the leakage of the refrigerant of the gas flowing through the first steam passage 5a and the second steam passage 5b and the inflow of the external gas into the first steam passage 5a and the second steam passage 5b.

The condenser 3 condenses the gaseous refrigerant by dissipating the heat of the gaseous refrigerant to the outside of the refrigeration cycle device 50a. The condenser 3 is, for example, an indirect heat exchanger such as a shell-and-tube heat exchanger and a plate heat exchanger, or a direct heat exchanger such as a spray heat exchanger and a direct heat exchanger having a filler. is there. The condenser 3 stores, for example, a liquid refrigerant.

The refrigerant in the refrigeration cycle device 50a is, for example, a low pressure refrigerant. An example of the operation of the refrigeration cycle device 50a when the main component of the refrigerant is water will be described. The temperature of the liquid refrigerant stored in the tank 23 in the evaporator 2 is a temperature near the saturation temperature with respect to the low pressure which is the pressure in the evaporator 2 or the saturation temperature with respect to the low pressure which is the pressure in the evaporator 2, for example, at 5 ° C. is there. Since the temperature of the liquid refrigerant stored in the evaporator 2 is low, if the liquid refrigerant stored in the evaporator 2 is used as the lubricating liquid for the bearing 7, the gaseous refrigerant tends to condense or condense in the multi-stage compressor 6. Is likely to occur. The temperature of the liquid refrigerant stored in the condenser 3 is a temperature near the saturation temperature with respect to the high pressure which is the pressure in the condenser 3 or the saturation temperature with respect to the high pressure which is the pressure in the condenser 3, and is, for example, 35 ° C. Since the temperature of the liquid refrigerant stored in the condenser 3 is high, if the liquid refrigerant stored in the condenser 3 is used as a lubricating liquid, the bearing 7 may not be cooled properly.

During the period in which the refrigeration cycle device 50a is operating, the pump 12 is operated to supply the lubricating liquid stored in the pressure vessel 10 to the bearing 7. Since the internal space of the pressure vessel 10 forms a part of the intermediate pressure space 20, the pressure in the internal space of the pressure vessel 10 is maintained at the intermediate pressure during the period in which the refrigeration cycle device 50a is operating. The temperature of the lubricating liquid stored in the pressure vessel 10 is an intermediate pressure saturation temperature or a temperature near the saturation temperature, for example, 20 ° C. The lubricating liquid stored in the pressure vessel 10 has a temperature suitable for lubricating the bearing 7, and the bearing 7 is appropriately cooled in the refrigeration cycle device 50a.

(Modification example)
The refrigeration cycle device 50a can be changed from various viewpoints. For example, the refrigeration cycle device 50a may include a fluid machine 1b, a fluid machine 1c, a fluid machine 1d, or a fluid machine 1e instead of the fluid machine 1a. Further, the refrigeration cycle device 50a may be modified as in the refrigeration cycle device 50b shown in FIG. The refrigeration cycle device 50b is configured in the same manner as the refrigeration cycle 50a except that the fluid machine 1f is provided instead of the fluid machine 1a. The refrigeration cycle device 50a may be modified to further include a flow path connecting the confluence point between the pressure vessel 10 and the inlet of the pump 12 on the first supply path 11 and the tank 23. Further, the refrigeration cycle device 50a is further provided with a flow path connecting a confluence point between the pressure vessel 10 on the first supply path 11 and the inlet of the pump 12 and a branch point on the liquid refrigerant flow path 25. May be changed. In this case, it is also possible to supply the liquid refrigerant stored in the tank 23 to the bearing 7 according to the operating condition of the multi-stage compressor 6.

The fluid machinery of the present disclosure can be applied to, for example, a large air conditioner or a turbo chiller.

1a, 1b, 1c, 1d, 1e, 1f Fluid machine 2 Evaporator 3 Condenser 5a First steam passage 5b Second steam passage 6 Multi-stage compressor 6a First compressor 6b Second compressor 6c Shaft 6p First suction port 6q 1st discharge port 6r 2nd suction port 6s 2nd discharge port 7 Bearing 8a 2nd supply path 8b 3rd supply path 8c 4th supply path 9 5th supply path 10 Pressure vessel 11 1st supply path 12 Pump 15 1st Return path 16 Second return path 18a First filter 18b Second filter 20 Intermediate pressure space 50a, 50b Refrigeration cycle equipment J Confluence point B Branch point

Claims (12)

A first compressor having a first suction port and a first discharge port, a second compressor having a second suction port and a second discharge port, and at least one of the first compressor and the second compressor. A multi-stage compressor including a bearing that supports a shaft for driving a compressor, wherein a gaseous compressor is sucked from the first suction port, compressed, and then discharged from the first discharge port. In addition, the multi-stage compressor in which the gaseous refrigerant discharged from the first discharge port of the second compressor is sucked from the second suction port, compressed, and then discharged from the second discharge port.
A pressure vessel that stores a lubricating liquid that contains the same type of substance as the main component of the refrigerant as the main component,
A first supply path that connects the pressure vessel and the bearing and supplies the lubricating liquid stored in the pressure vessel to the bearing.
A pump located on the first supply path and delivering the lubricating fluid towards the bearings,
A first return path that connects the bearing and the pressure vessel and returns the lubricating liquid that has passed through the bearing to the pressure vessel.
An intermediate pressure maintained at a pressure higher than the pressure of the gaseous refrigerant at the first suction port and lower than the pressure of the gaseous refrigerant at the second discharge port during the operating period of the multi-stage compressor. With space,
The internal space of the pressure vessel forms a part of the intermediate pressure space.
Fluid machine. Claim 1 that the intermediate pressure space is filled with the gaseous refrigerant that has passed through the first discharge port and has not passed through the second suction port during the operating period of the multi-stage compressor. The fluid machinery described in. The intermediate pressure space connects the first discharge port and the pressure vessel, and a second supply path for guiding the gaseous refrigerant discharged from the first discharge port to the internal space of the pressure vessel. The fluid machine according to claim 1 or 2, wherein the pressure vessel and the second suction port are connected to each other, and a third supply path for guiding the gaseous refrigerant to the second compressor is included. .. The intermediate pressure space connects the first discharge port and the second suction port, and has a fourth supply path for guiding the gaseous refrigerant to the second compressor, the pressure vessel, and the first. (Iv) The invention according to claim 1 or 2, which is connected to a confluence point on the supply path and includes a fifth supply path for guiding a gas generated by vaporization from the lubricating fluid to the second compressor. Fluid machine. A branch point located between the outlet of the pump and the bearing on the first supply path and the pressure vessel are connected by bypassing the bearing, and a part of the lubricating fluid in the first supply path. The fluid machine according to any one of claims 1 to 4, further comprising a second return path for returning the pressure vessel to the pressure vessel. The fluid machine according to claim 5, further comprising a first filter arranged on the first supply path to reduce the amount of impurities contained in the lubricating liquid. The fluid machine according to claim 6, wherein the first filter is arranged between the outlet of the pump and the branch point on the first supply path. The fluid machine according to claim 6, wherein the first filter is arranged between the branch point and the bearing on the first supply path. The fluid machine according to claim 8, further comprising a second filter arranged between the outlet of the pump and the branch point on the first supply path to reduce the amount of impurities contained in the lubricating liquid. The fluid machine according to claim 8, further comprising a second filter arranged on the second return path to reduce the amount of impurities contained in the lubricating liquid. The fluid machine according to any one of claims 1 to 10, wherein the refrigerant and the lubricating liquid contain water as a main component. The fluid machine according to any one of claims 1 to 11.
An evaporator that evaporates a liquid refrigerant to generate the gaseous refrigerant, and
A first vapor path that connects the evaporator and the first suction port and guides the gaseous refrigerant to the first compressor, and
A condenser that condenses the gaseous refrigerant discharged from the second discharge port, and
A refrigeration cycle apparatus comprising a second steam passage that connects the second discharge port and the condenser and guides the refrigerant of the gas discharged from the second discharge port to the condenser.

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