JPH11294879A - Refrigerating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand an air conditioning operation area by solving problems of seizure of a compressor due to the insufficiency of a lubricating oil, poor lubrication due to a drop in viscosity and the like. SOLUTION: A refrigerant circuit of a multi-air conditioner for a building is provided with a turbo compressor 1 wherein a drive shaft 10 is supported non-contact by dynamic pressure gas bearings 34 and 35 as oilless compressor making a double-stage compression. A first impeller chamber 91, a first vortex chamber 13, a motor chamber 6, a second impeller chamber 92 and a second vortex chamber 14 are formed being sectioned in a casing 2 of the turbo compressor 1 sequentially from above. A refrigerant sucked in from a suction pipe 12 is compressed, introduced once into the motor chamber 6 through the first vortex chamber 13 and a first communication path 15 and compressed by the second impeller chamber 92 through the second communication path 18 to be delivered from a delivery pipe 12 through the second vortex chamber 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refrigeration system,
In particular, the present invention relates to a refrigeration apparatus provided with a turbo compressor.

[0002]

2. Description of the Related Art Many conventional refrigeration systems, such as a building air conditioner and a room air conditioner, have one or more outdoor units having a compressor and an outdoor heat exchanger, and an indoor heat exchanger. One or a plurality of indoor units provided with a vessel were connected by a refrigerant pipe.

In the conventional refrigeration apparatus described above, a compressor in which lubricating oil is sealed in a casing is used as disclosed in, for example, Japanese Patent Publication No. 7-18424. In this type of compressor, operation is performed while supplying lubricating oil to sliding parts inside the compressor. That is, an oil film of lubricating oil is formed between the sliding metal members so as not to directly contact each other, thereby preventing abrasion and burning. Further, the lubricating oil enters the gap between the components forming the compression chamber and forms an oil film that closes the gap. As a result, the compression chamber is hermetically sealed.

[0004]

However, the conventional refrigeration system has many problems due to the necessity of lubricating oil for the compressor. Hereinafter, those problems will be listed and described.

[0005] -Problem 1 (retention of lubricating oil)-In the conventional refrigeration apparatus, if the lubricating oil discharged from the compressor stays somewhere in the refrigeration apparatus, the lubricating oil does not return to the compressor. As a result, the lubricating oil in the compressor gradually decreases and eventually runs short. And ultimately,
Lubricating oil did not spread to the sliding part of the compressor, causing wear and seizure. Therefore, the conventional refrigeration system cannot be said to have sufficiently high reliability.

-Problem 2 (Dilution of lubricating oil)-In a conventional refrigeration system, a compatible lubricating oil is often used. Therefore, when a large amount of refrigerant is dissolved in the lubricating oil stored inside the compressor, the lubricating oil is diluted by the refrigerant, and the viscosity decreases. When the compressor was operated in such a state, the lubricating oil could not sufficiently lubricate the sliding portion, so that abrasion and seizure were likely to occur.

-Problem 3 (comfort)-Further, when the compressor is started in a state in which the refrigerant is dissolved in the lubricating oil stored in the compressor, the lubricating oil forms and the lubricating oil contained in the discharge gas is discharged. The amount increases. Therefore, the lubricating oil inside the compressor will be insufficient if this state is maintained.

As a countermeasure, in the case of a variable speed compressor, the operating frequency is often increased stepwise from the start of the operation with respect to the operating time to suppress an increase in oil rise due to forming.

Generally, immediately after the start of the refrigerating apparatus, the difference between the room temperature and the set temperature of the refrigerating apparatus is large. Therefore, in order to quickly bring the room temperature to the set temperature, it is desirable to operate at the highest frequency immediately after starting.

[0010] However, in the conventional refrigeration system, it was not possible to operate at the highest frequency immediately after the start due to the above-mentioned problem of forming. For this reason, there has been a problem that the room temperature cannot be quickly set to the set temperature, and the comfort is low.

Further, in the conventional refrigeration system, when operating in a steady state, if the heat load in the room is reduced, the required capacity is reduced, so that the operating frequency of the compressor is reduced, and the refrigerant in the refrigeration system is accordingly reduced. Flow velocity decreases. Therefore, the lubricating oil discharged from the compressor is difficult to return to the compressor, and the lubricating oil inside the compressor often runs short.

[0012] As a countermeasure, a lubricating oil recovery operation is usually performed for returning the retained lubricating oil to the compressor for several minutes at regular intervals. The lubricating oil recovery operation is performed by increasing the operating frequency of the compressor and increasing the flow rate of the refrigerant in the refrigeration system.

However, when the lubricating oil recovery operation is performed, the balance between the heat load of the room and the capacity of the refrigeration system is lost, so that there is a problem that the room temperature fluctuates and the comfort is impaired.

On the other hand, it is conceivable to add various operation controls as means for suppressing the above-mentioned decrease in comfort. However, in this case, the cost of the entire refrigeration system increases.

-Problem 4 (Oil compression)-In a compressor in which a compressor suction pipe is directly connected to a compression chamber, when lubricating oil circulates through a refrigerating device and returns to the compressor, oil compression is performed. May occur. In this case, there is a problem that the compression chamber is broken or the load on the sliding section becomes excessive due to an abnormal increase in the pressure of the compression chamber, and wear and seizure of the sliding section increase.

-Problem 5 (connection of a plurality of compressors)-Some air conditioners for buildings use a plurality of compressors connected to each other. In such an apparatus, the suction pipe and the discharge pipe are connected, and between the casings, an oil equalizing pipe that is opened in the lateral direction near the specified oil level of each oil reservoir is connected. With such a configuration, a pressure difference is generated between the casings based on the difference in the sharing capacity of each compressor, and the lubricating oil flows from the high-pressure side casing to the low-pressure side casing so that the oil level height is increased. I am trying to correct my balance.

However, even if the oil level in the casing is low, the return oil supplied to each sliding portion is scattered by the rotating body, returns to a large amount of mist and returns to the oil pool.
Since this mist is constantly falling inside the casing,
Even when the oil level of the compressor on the high pressure side is equal to or less than the specified oil level, a large amount is transferred to the compressor on the low pressure side through the oil equalizing pipe, and the compressor on the high pressure side runs short of lubricating oil, and wear and seizure increase. On the other hand, the compressor on the low pressure side sometimes becomes excessively lubricated and causes oil compression. Therefore, such a conventional refrigeration system has a problem of low reliability.

-Issue 6 (oil return)-Also, when the connection pipe between the outdoor unit and the indoor unit is very long, such as in an air conditioner for a building, or where the outdoor unit and the indoor unit are installed. When the height difference is large, it is difficult for the lubricating oil discharged from the compressor to circulate in the refrigerating device and return to the compressor, and there is a problem that the lubricating oil inside the compressor runs short. for that reason,
In the conventional refrigeration system, there are restrictions on the length of the connection pipe and the height difference regarding the installation of the outdoor unit and the indoor unit.

-Problem 7 (Adhesion of lubricating oil to heat exchanger and piping)-In the conventional refrigeration system, since the lubricating oil is discharged from the compressor, a condenser or a part of the refrigeration system, Lubricating oil adhered to the tube wall of the evaporator, and the heat transfer coefficient was sometimes reduced as compared with the case without lubricating oil. In addition, there is a problem that pressure loss of the pipe increases due to the lubricating oil adhering to the pipe wall of the pipe.

In a refrigerating apparatus using a variable speed compressor, the operating frequency is increased in order to compensate for a decrease in heat transfer coefficient in a condenser or an evaporator. Therefore, the compressor input increases, and the compressor efficiency decreases. On the other hand, in the case of a constant speed compressor, the capacity is reduced and the compressor efficiency is reduced.

When the pressure loss in the piping increases, the suction pressure of the compressor decreases, and the density of the suction gas decreases. Therefore, there is a problem that the amount of circulating refrigerant is reduced and the capacity is reduced. Therefore, there is a problem that the efficiency of the compressor is reduced as in the case of the reduction in the heat transfer coefficient.

-Problem 8 (Chemical Properties of Lubricating Oil)-In a conventional refrigeration system, a refrigerant containing chlorine is generally used. However, when this kind of refrigerant is released into the atmosphere, it is highly likely that the refrigerant will adversely affect the global environment, such as destroying the ozone layer surrounding the earth. Therefore, in the future, it is considered necessary to replace the refrigerant with a refrigerant that does not contain chlorine and does not adversely affect the earth, for example, an HFC-based refrigerant.

By the way, when using an HFC-based refrigerant containing no chlorine, the lubricating oil is mixed with the HFC-based refrigerant so that the lubricating oil contained in the discharge gas of the compressor returns to the compressor promptly. Solubility is required.

In the conventional refrigerant containing chlorine, chlorine in the refrigerant is bonded to the metal surface of the sliding portion inside the compressor to form a compound film, and the metal surfaces sliding with each other are directly contacted. It is becoming clear that it had the effect of avoiding contact with metal and preventing wear and seizure. Therefore, in addition to the mutual solubility described above,
It is required that the FC-based refrigerant has the same lubricating properties as conventional ones.

At the present stage, various candidates for the HFC-based refrigerant are considered. Therefore, every time the refrigerant changes, a lubricating oil excellent in mutual solubility and lubricating properties for the refrigerant must be selected each time, and there is a problem that development takes time and effort.

-Problem 9 (ester oil)-At present, ester oil is selected as a lubricating oil having mutual solubility with HFC-based refrigerants and excellent lubricating properties, but this ester oil has a hygroscopic property. It is high and has the property of producing fatty acids by hydrolysis. Then, there is a problem that metal soap or the like generated by combining the fatty acid with the metal of each part of the freezing device is clogged in a capillary tube or the like used as a decompression mechanism, thereby impairing the function of the freezing device.

The inventor of the present invention has devised to use a turbo compressor as a compressor of a refrigeration system in order to overcome the above problems 1 to 9 (see Japanese Patent Application No. 8-309185).

However, for various reasons, it is desired to expand the air-conditioning operation area more than before and to improve the operation efficiency.

The present invention has been made in view of the above points, and an object of the present invention is to provide a refrigeration system equipped with a turbo compressor, such as expansion of a controllable air-conditioning operation area and improvement of operation efficiency. The goal is to improve performance.

[0030]

In order to achieve the above object, the present invention comprises a turbo compressor provided with a plurality of stages of impellers. Also, a plurality of turbo compressor units are provided in series.

Specifically, the means taken by the first invention are:
A refrigerant circuit in which a turbo compressor (1) for compressing the refrigerant, a heat source side heat exchanger (56a) for condensing or evaporating the refrigerant, and a utilization side heat exchanger (56b) for evaporating or condensing the refrigerant are connected in order. (5A) is configured, the turbo compressor (1) is provided with a pressure increasing mechanism, and is rotatably supported in a non-contact state by a gas bearing (34, 35) formed by the pressure increasing mechanism and the refrigerant. A drive shaft (10) and a plurality of impellers (8, 9, 43) connected to the drive shaft (10) and compressing the refrigerant in multiple stages are provided.

According to the above-mentioned specific features of the invention, since the drive shaft (10) is supported by the gas bearings (34, 35) in a non-contact state, lubricating oil is not required. Therefore, various problems associated with the use of the lubricating oil are overcome. Further, since a plurality of stages of impellers are provided for compressing the refrigerant in multiple stages, the compression ratio of the refrigerant is increased, and the controllable air-conditioning operation area is expanded.

According to a second aspect, in the first aspect, the impeller of the turbo compressor (1) is constituted by a two-stage or three-stage impeller (8, 9, 43). It is what it was.

According to the above-mentioned invention specifying matter, the air-conditioning operation area required for practical use can be sufficiently covered while suppressing an increase in the cost of the apparatus.

The means adopted by the third invention is, as shown in FIG. 3, the turbo compressor (1) according to the second invention,
A first impeller chamber (91), a first spiral chamber (13) located around the first impeller chamber (91), a motor chamber (6), a second impeller chamber (92), and the second impeller chamber (92) and a casing (2) provided with a second spiral chamber (14) in order from one end to the other end, and a motor body (23, 23) fixed in the motor chamber (6). Motor (2) having a drive shaft (10) extending from the motor body (23, 24) to both the one end and the other end.
2), a suction passage (95) for guiding the refrigerant drawn from the suction pipe (12) to the suction side of the first impeller chamber (91), and a drive of the motor (22) in the first impeller chamber (91). A first impeller (8) that is connected to a shaft (10), sucks refrigerant from the suction passage (95) from the one end side, compresses the refrigerant, and discharges the compressed refrigerant to the first spiral chamber (13); The refrigerant in the chamber (13) is
And a second communication path (18) for guiding the refrigerant in the motor chamber (6) to the suction side of the second impeller chamber (92).
The second impeller chamber (92) is connected to the drive shaft (10) of the motor (22) in the second impeller chamber (92), sucks refrigerant from the second communication path (18) from the other end side, compresses the refrigerant, and (2) It is provided with a second impeller (9) for discharging to the spiral chamber (14) and a discharge passage (96) for guiding the refrigerant in the second spiral chamber (14) to a discharge pipe (21). It is.

According to the above-mentioned invention, the low-pressure refrigerant flowing from the suction pipe (12) flows into the first impeller chamber (91),
After the first-stage compression is performed by the first impeller (8) to become the intermediate-pressure refrigerant, the first spiral chamber (13) and the first communication passage (1) are compressed.
It flows into the motor room (6) through 5). The intermediate-pressure refrigerant in the motor chamber (6) passes through the second communication passage (18) to the second impeller chamber.
(92), is compressed in the second stage by the second impeller (9), and becomes high-pressure refrigerant. The high-pressure refrigerant passes through the second spiral chamber (14) and the discharge passage (96), and is discharged to the discharge pipe (21).

The means adopted by the fourth invention is that, as shown in FIG. 6, in the second invention, the turbo compressor (1a)
A first impeller chamber (91), a first spiral chamber (13) located around the first impeller chamber (91), a motor chamber (6), a second impeller chamber (92), and the second impeller chamber (92) and a casing (2) provided with a second spiral chamber (14) in order from one end to the other end, and a motor body (23, 23) fixed in the motor chamber (6). Motor (2) having a drive shaft (10) extending from the motor body (23, 24) to both the one end and the other end.
2), a suction passage (95) for guiding the refrigerant drawn from the suction pipe (12) to the suction side of the first impeller chamber (91), and a drive of the motor (22) in the first impeller chamber (91). A first impeller (8) that is connected to a shaft (10), sucks refrigerant from the suction passage (95) from the one end side, compresses the refrigerant, and discharges the compressed refrigerant to the first spiral chamber (13); A communication path (15a) for guiding the refrigerant in the chamber (13) to the suction side of the second impeller chamber (92), and is connected to the drive shaft (10) of the motor (22) in the second impeller chamber (92). A second impeller (9) that sucks and compresses the refrigerant from the communication path (15a) from the other end side and discharges the compressed refrigerant to the second spiral chamber (14); Discharge pipe for refrigerant (21)
Discharge passage (96), the suction pipe (12) and the motor chamber
And a pressure equalizing pipe (36) communicating with (6).

The means adopted by the fifth invention is, as shown in FIG. 7, the turbo compressor (1b) according to the second invention,
A first impeller chamber (91), a first spiral chamber (13) located around the first impeller chamber (91), and a second impeller chamber (92) and located around the second impeller chamber (92) The second spiral chamber to do (14)
And a casing (2) in which a motor chamber (6) is provided in order from one end to the other end, a motor body (23, 24) fixed in the motor chamber (6), and the motor body (23 , 24), a motor (22) having a drive shaft (10) extending to the one end, and a suction pipe (12).
A suction passage (95) for guiding the refrigerant sucked from the suction port of the first impeller chamber (91) to a suction side of the first impeller chamber (91), and a drive shaft (10) of the motor (22) in the first impeller chamber (91); Inhalation passage (95)
A first impeller (8) that draws in refrigerant from the one end from the one end side, compresses the refrigerant, and discharges the refrigerant to the first spiral chamber (13);
A communication path (15a) for guiding the refrigerant in the spiral chamber (13) to the suction side of the second impeller chamber (92), and a drive shaft (10) of the motor (22) in the second impeller chamber (92). Connected to the communication path (15
a) a second impeller (9) that sucks the refrigerant from one end side and compresses the refrigerant and discharges the refrigerant into the second spiral chamber (14); and discharges the refrigerant in the second spiral chamber (14) to a discharge pipe (21). (96)
And a pressure equalizing pipe (36) communicating the suction pipe (12) with the motor chamber (6).

As shown in FIG. 8, the means adopted by the sixth invention is that, in the second invention, the turbo compressor (1c)
A second impeller chamber (92) and a second spiral chamber (14) located around the second impeller chamber (92); and a first impeller chamber (91) and located around the first impeller chamber (91). The first spiral chamber to do (13)
And a casing (2) in which a motor chamber (6) is provided in order from one end to the other end, a motor body (23, 24) fixed in the motor chamber (6), and the motor body (23 , 24), a motor (22) having a drive shaft (10) extending to the one end, and a suction pipe (12).
A suction passage (95) for guiding the refrigerant sucked from the suction port of the first impeller chamber (91) to a suction side of the first impeller chamber (91), and a drive shaft (10) of the motor (22) in the first impeller chamber (91); Inhalation passage (95)
A first impeller (8) that draws in refrigerant from the one end from the one end side, compresses the refrigerant, and discharges the refrigerant to the first spiral chamber (13);
A communication path (15a) for guiding the refrigerant in the spiral chamber (13) to the suction side of the second impeller chamber (92), and a drive shaft (10) of the motor (22) in the second impeller chamber (92). Connected to the communication path (15
a) a second impeller (9) that sucks the refrigerant from the other end from the other end side and compresses and discharges the refrigerant into the second spiral chamber (14); and discharges refrigerant in the second spiral chamber (14) through a discharge pipe ( Discharge passage leading to 21) (96)
And a pressure equalizing pipe (36) communicating the suction pipe (12) with the motor chamber (6).

As shown in FIG. 9, the means adopted by the seventh invention is that, in the second invention, the turbo compressor (1d) comprises:
A second impeller chamber (92) and a second spiral chamber (14) located around the second impeller chamber (92); and a first impeller chamber (91) and located around the first impeller chamber (91). The first spiral chamber to do (13)
And a casing (2) in which a motor chamber (6) is provided in order from one end to the other end, a motor body (23, 24) fixed in the motor chamber (6), and the motor body (23 , 24), a motor (22) having a drive shaft (10) extending to the one end, and a suction pipe (12).
A suction passage (95) for guiding the refrigerant sucked from the suction port of the first impeller chamber (91) to a suction side of the first impeller chamber (91), and a drive shaft (10) of the motor (22) in the first impeller chamber (91); Inhalation passage (95)
A first impeller (8) that sucks in refrigerant from the other end from the other end side, compresses the refrigerant, and discharges the refrigerant to the first spiral chamber (13).
A communication path (15a) for guiding the refrigerant in the spiral chamber (13) to the suction side of the second impeller chamber (92), and a drive shaft (10) of the motor (22) in the second impeller chamber (92). Connected to the communication path (15
a) a second impeller (9) that sucks the refrigerant from one end side and compresses the refrigerant and discharges the refrigerant into the second spiral chamber (14); and discharges the refrigerant in the second spiral chamber (14) to a discharge pipe (21). (96)
And a pressure equalizing pipe (36) communicating the suction pipe (12) with the motor chamber (6).

According to the third to seventh aspects of the present invention, the low-pressure refrigerant flowing from the suction pipe (12) flows into the first impeller chamber (91), and the low-pressure refrigerant flows through the first impeller (8). The compression of the stage is performed, and it becomes a medium pressure refrigerant. The intermediate-pressure refrigerant flows into the second impeller chamber (92) through the first swirl chamber (13) and the communication path (15a), and is compressed by the second impeller (9) in the second stage, so that the high-pressure refrigerant is discharged. It becomes a refrigerant. High pressure refrigerant
After passing through the second volute chamber (14) and the discharge passage (96), the discharge pipe (21)
Is discharged.

As shown in FIG. 10, the means adopted by the eighth invention is the turbo compressor (1e) according to the second invention.
The second impeller chamber (92) and the second spiral chamber (14) located around the second impeller chamber (92), and the third impeller chamber (93) and the periphery of the third impeller chamber (93) The third swirl chamber (9
4), the motor chamber (6), the first impeller chamber (91) and the first impeller chamber (91).
A casing (2) in which a first spiral chamber (13) located around the impeller chamber (91) is provided in order from one end to the other end, and a motor body (6) fixed in the motor chamber (6) 23, 24), a motor (22) having a drive shaft (10) extending from the motor body (23, 24) to both the one end and the other end, and a refrigerant sucked from a suction pipe (12). A suction passage (95) leading to the suction side of the first impeller chamber (91), and a drive shaft (10) of the motor (22) in the first impeller chamber (91); Impeller (8) that draws in refrigerant from the other end side and compresses and discharges the refrigerant into the first spiral chamber (13), and transfers the refrigerant in the first spiral chamber (13) to the second impeller chamber. A first communication path (15) leading to the suction side of the motor (22) and a drive shaft (10) of the motor (22) in the second impeller chamber (92);
A second impeller (9) that sucks in the refrigerant from the one end from the one end side, compresses the refrigerant, and discharges the refrigerant into the second spiral chamber (14), and a refrigerant in the second spiral chamber (14) with the third impeller. A second communication path (18) leading to the suction side of the chamber (93) and a drive shaft (10) of the motor (22) in the third impeller chamber (93); A third impeller (43) that draws in refrigerant from the one end side, compresses the refrigerant, and discharges the refrigerant to the third spiral chamber (94);
A discharge passageway (96) for guiding the refrigerant in the third spiral chamber (94) to the discharge pipe (21), and a pressure equalizing pipe (36) communicating the suction pipe (12) and the motor chamber (6). It has been prepared.

According to the above invention, the low-pressure refrigerant flowing from the suction pipe (12) flows into the first impeller chamber (91),
After the first stage compression is performed by the first impeller (8),
It flows into the second impeller chamber (92) through the first spiral chamber (13) and the first communication path (15). The refrigerant flowing into the second impeller chamber (92) is compressed by the second impeller (9) in the second stage to further increase its pressure, and is further compressed through the second spiral chamber (14) and the second communication passage (18). It flows into the three impeller chamber (93). Third impeller room (9
The refrigerant flowing into (3) is compressed by the third impeller (43) in the third stage and further pressurized, passes through the third spiral chamber (94) and the discharge passage (96), and flows through the discharge pipe (21). ).

As shown in FIG. 11, the means adopted by the ninth invention is the turbo compressor (1f) according to the second invention.
A motor chamber (6), a second impeller chamber (92) and a second spiral chamber (14) located around the second impeller chamber (92);
A casing (2) provided with an impeller chamber (91) and a first spiral chamber (13) located around the first impeller chamber (91) in order from one end to the other end; and a motor chamber (6). ), A motor (22) having a motor body (23, 24) and a drive shaft (10) extending from the motor body (23, 24) to both the one end and the other end. The refrigerant sucked from the suction pipe (12)
And a first communication path (1A) for guiding the refrigerant in the motor chamber (6) to the suction side of the first impeller chamber (91).
5A) and the motor (22) in the first impeller chamber (91).
And the refrigerant from the first communication path (15A) is sucked from the other end side and compressed to compress the first spiral chamber.
(13) and a first impeller (8) and the first spiral chamber (1).
3) a second communication passageway (18A) for guiding the refrigerant in the second impeller chamber (92) to the suction side of the second impeller chamber (92), and a drive shaft (10) of the motor (22) in the second impeller chamber (92). And the second communication passage (18)
A), a second impeller (9) that draws in the refrigerant from the one end side and compresses and discharges the refrigerant into the second spiral chamber (14), and discharges the refrigerant in the second spiral chamber (14) to a discharge pipe (21). (96)
And that it is provided.

According to the above-mentioned invention specific matter, a low-pressure refrigerant flows into the motor chamber (6) from the suction pipe (12) through the suction passage (12A). The refrigerant in the motor chamber (6) flows into the first impeller chamber (91) through the first communication passage (15A), is compressed by the first impeller (8) in the first stage, and is converted into intermediate-pressure refrigerant. Become. The intermediate-pressure refrigerant flows into the second impeller chamber (92) through the first spiral chamber (13) and the second communication path (18A), and is compressed by the second impeller (9) in the second stage. It becomes a high-pressure refrigerant. The high-pressure refrigerant passes through the second spiral chamber (14) and the discharge passage (96), and is discharged to the discharge pipe (21).

As shown in FIG. 12, a means adopted by the tenth invention is a turbo compressor (1h) for compressing a refrigerant, a heat source side heat exchanger (56a) for condensing or evaporating the refrigerant, and The use side heat exchanger (56b) for evaporating or condensing is connected in order to form a refrigerant circuit (5A), and the turbo compressor (1
h) includes a plurality of turbo compressor units (65, 66) connected in series so as to compress the refrigerant in multiple stages, and the drive shaft (90A, 90B) of each of the turbo compressor units (65, 66). ) Are provided with a booster mechanism (114A, 114B, 119A, 119B), and the booster mechanism (11
4A, 114B, 119A, 119B) and a refrigerant, and are rotatably supported in a non-contact state by gas bearings (117A, 117B).

According to the above-mentioned specific features of the invention, the drive shafts (90A, 90B) of the turbo compressor units (65, 66) are
A, 117B), so that lubricating oil is not required. Therefore, various problems associated with the use of the lubricating oil are overcome. Also, multiple turbo compressor units (6
5, 66) are connected in series, the compression ratio of the refrigerant is increased, and the controllable air-conditioning operation area is expanded.

The means adopted by the eleventh invention is, as shown in FIG. 2, the refrigerant circuit (5
A) is that the plurality of use side heat exchangers (56b) are configured in a multi-circuit connected in parallel with each other.

According to the above-mentioned invention, since no lubricating oil is used, the performance and reliability of the apparatus are not reduced even if the circuit is complicated. Therefore, the first to tenth
The effect of the invention of (1) will be more remarkably exhibited.

As shown in FIG. 13 or FIG. 14, the means adopted by the twelfth invention is the same as the first to eleventh inventions, except that the discharge pipe (21) and the suction pipe (12) are connected to a turbo compressor ( 1f, 1h)
And a bypass passage (71) for bypassing and connecting the turbo compressor (1f, 1h) to close the bypass passage (71) during the compression operation of the turbo compressor (1f, 1h). When the compressor (1f, 1h) stops the compression operation,
An opening / closing means (72) for opening the bypass passage (71) so as to eliminate a pressure difference between the inside of the suction pipe (12) and the inside of the suction pipe (12).

According to the above-mentioned invention specifying matter, the turbo compressor (1
During the compression operation of (f, 1h), the bypass passage (71) is closed, and the refrigerant sucked into the turbo compressor (1f, 1h) from the suction pipe (12) is compressed in multiple stages, and the discharge pipe (21) Is discharged.
On the other hand, when the compression operation of the turbo compressor (1f, 1h) is stopped,
The opening / closing means (72) opens the bypass passage (71). And
The high-pressure refrigerant inside the discharge pipe (21) flows into the suction pipe (12) through the bypass passage (71), and the inside of the discharge pipe (21) and the suction pipe (1).
2) The pressure inside is immediately equalized. As a result, the backflow of the refrigerant that tries to equalize through the compressor immediately after the operation of the turbo compressor (1f, 1h) is avoided, and the gas bearings (34, 35, 1
17A, 117B), the drive shaft (10, 90
A, 90B) is prevented from rotating in the reverse direction.

As shown in FIG. 15, the means adopted by the thirteenth invention is the same as that of the first to twelfth inventions, except that the discharge pipe (2
1) is provided with a backflow prevention means (74) that allows only the discharge of the refrigerant from the turbo compressor (1f, 1h).

According to the above-mentioned invention specifying matter, the turbo compressor (1
During the compression operation of (f, 1h), the discharge operation of the refrigerant from the turbo compressor (1f, 1h) to the discharge pipe (21) is maintained, and a multi-stage compression operation of the refrigerant is performed. On the other hand, when the compression operation of the turbo compressor (1f, 1h) is stopped, the pressure inside the discharge pipe (21) becomes higher than that inside the turbo compressor (1f, 1h). However, due to the backflow prevention means (74), the turbo compressor (1) is discharged from the discharge pipe (21).
Backflow of the refrigerant toward f, 1h) is prevented. As a result, the reverse rotation of the drive shaft (10, 90A, 90B) in a state where the action of the gas bearings (34, 35, 117A, 117B) is not exhibited is prevented.

As shown in FIG. 15, the means of the fourteenth invention is the same as that of the first to thirteenth inventions, except that the suction pipe (1
2) is provided with a backflow prevention means (73) that allows only the suction of the refrigerant into the turbo compressors (1f, 1h).

According to the above-mentioned invention specifying matter, the turbo compressor (1
f, 1h), the turbo compressor is connected through the suction pipe (12).
The operation of sucking the refrigerant into (1f, 1h) is maintained, and a multi-stage compression operation of the refrigerant is performed. Meanwhile, turbo compressors (1f, 1h)
When the compression operation is stopped, the pressure inside the suction pipe (12) becomes lower than that inside the turbo compressor (1f, 1h). However, the backflow prevention means (73) prevents the backflow of the refrigerant from the turbo compressor (1f, 1h) toward the suction pipe (12). as a result,
The reverse rotation of the drive shaft (10, 90A, 90B) in a state where the action of the gas bearings (34, 35, 117A, 117B) is not exhibited is prevented.

As shown in FIG. 16, the means adopted by the fifteenth invention is that, in the first to fourteenth inventions, when the operation of the turbo compressor (1f, 1h) is stopped, the inside of the discharge pipe (21) is stopped. After the motor (22) of the turbo compressor (1f, 1h) is gradually decelerated so that the pressure difference between the turbo compressor (1f, 1h) and the inside of the suction pipe (12) becomes equal to or less than a predetermined value, the motor (22) is stopped. A time control means (131) is provided.

According to the above invention specifying matter, the turbo compressor (1
f, 1h), the stop-time control means (131) gradually decelerates the motor (22) of the turbo compressor (1f, 1h) to stop the discharge pipe (21).
The pressure difference between the inside of the compressor and the inside of the suction pipe (12) is reduced to a predetermined value or less that does not cause the backflow of the refrigerant inside the compressor. As a result, the differential pressure becomes equal to or less than the predetermined value, and the motor (22) stops. Therefore, the backflow of the refrigerant inside the turbo compressor (1f, 1h) is prevented, and the reverse rotation of the drive shaft (10, 90A, 90B) in a state where the function of the gas bearing (34, 35, 117A, 117B) is not exhibited. Is prevented.

The measures taken by the sixteenth invention are as follows.
In the fifteenth invention, when the operation of the turbo compressor (1f, 1h) is stopped, the rotation speed of the motor (22) of the turbo compressor (1f, 1h) is gradually reduced, and then the rotation speed is reduced to near zero. And a stop-time control means (131) for stopping the motor (22) after maintaining the predetermined low rotation speed for a predetermined time.

According to the above invention specifying matter, the turbo compressor (1
When the operation of (f, 1h) is stopped, the stop time control means (131) gradually reduces the rotation speed of the motor (22) of the turbo compressor (1f, 1h). Thereafter, the rotation speed is maintained at a predetermined low rotation speed near zero for a predetermined time, and the motor (22) is stopped. By such an operation, when the motor (22) is stopped, the pressure difference between the inside of the discharge pipe (21) and the inside of the suction pipe (12) is reliably reduced, and the refrigerant inside the turbo compressor (1f, 1h) is reduced. Is reliably prevented from flowing back.

[0060]

Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1>-Configuration of building multi-air conditioner (50)-As shown in FIGS. 1 and 2, the refrigeration apparatus according to the present embodiment includes a plurality of outdoor units (51) and a plurality of outdoor units (51). Indoor unit
(52), air conditioner for each room
(50). Specifically, multi air conditioners for buildings (50)
Means two outdoor units (51) and nine indoor units (52)
And a refrigerant circuit (5A) as a multi-circuit configured by being connected by a refrigerant pipe (53) and installed in the building (60).

The outdoor unit (51) contains a compressor (1), a four-way switching valve (54), an outdoor heat exchanger (56a), and a pressure reducing mechanism (55). Although not shown, the outdoor unit (51) also includes a blower, a control device, and the like for supplying air to the outdoor heat exchanger (56a).

On the other hand, the indoor unit (52) is provided with an indoor heat exchanger (56b) and a blower (not shown), and further includes a control device (not shown) for adjusting the air volume of the blower.

The outdoor unit (51) and the indoor unit (5)
Various valves (not shown) for switching the refrigerant flow path and adjusting the flow rate of the refrigerant are provided in the refrigerant pipe (53) between the indoor unit and the indoor unit (53) according to the load of each room. It is configured such that the supply amount of the refrigerant to 52) is adjusted.

The multi air conditioner (50) for the building does not use a lubricating oil, so that no oil separator is provided. Further, no U trap is provided to prevent a large amount of lubricating oil from returning to the compressor (1) at one time. Further, it is not necessary to dispose the refrigerant pipe (53) on a downward slope in order to prevent the accumulation of the lubricating oil. Therefore, the refrigerant pipe (53)
It is easily installed in.

-Configuration of Compressor (1)-Next, the configuration of the compressor (1) will be described. The compressor (1) is a compressor that does not require lubricating oil, that is, an oilless compressor. Specifically, as shown in FIG. 3, a so-called multi-stage turbo compressor for increasing the pressure of a refrigerant in multiple stages.

In FIG. 3, an upper partition wall is located inside the casing (2) at a position having a predetermined dimension below the upper end.
In (3), lower partition walls (4) are provided at positions having predetermined dimensions upward from the lower end. The upper partition wall (3) partitions the internal space of the casing (2) into an upper first impeller chamber (91) and a lower motor chamber (6). On the other hand, the lower partition wall (4) partitions the internal space of the casing (2) into a lower second impeller chamber (92) and an upper motor chamber (6).

The first impeller chamber (91) and the second impeller chamber (9)
2) is a first impeller formed at the center of the casing (2) in the axial section and connected to both sides of the drive shaft (10).
(8) and a storage room for storing the second impeller (9).

The first impeller chamber (91) and the second impeller chamber (9)
The shape of 2) is a substantially frustoconical shape whose inner diameter gradually increases toward the center of the casing (2). The first impeller (8) is inside the first impeller chamber (91) and the second impeller (9) is inside the second impeller (91).
Each is rotatably housed inside the impeller chamber (92). The first impeller (8) and the second impeller (9) are composed of a plurality of substantially triangular plate blades (11, 11,...) Provided radially around a vertical axis, and are radial type for generating an outward radial flow. Of the rotating body.

A suction pipe (12) is connected to the center of the upper end surface of the casing (2). A suction passage (95) is formed between the suction pipe (12) and the first impeller chamber (91). The suction passage (95) transfers the refrigerant along the axial direction of the first impeller (8) from above the first impeller (8) to the first impeller chamber (9).
It leads to 1).

A first spiral chamber (13) and a second spiral chamber (14) are formed around the outer periphery of the first impeller chamber (91) and the outer periphery of the second impeller chamber (92), respectively. These spiral chambers (13),
(14) is the impeller chamber via diffusers (101) and (102).
It communicates with (91) and (92). Diffuser (101), (102)
Is a portion that converts the dynamic pressure of the refrigerant discharged by applying centrifugal force by the impellers (8) and (9) to static pressure. Spiral chamber
(13) and (14) are configured to collect the pressurized refrigerant.

The first spiral chamber on the side surface of the casing (2)
At a position corresponding to (13), a first communication path (15) for guiding the refrigerant pressurized by the first impeller (8) to the motor chamber (6) is provided. The first communication path (15) is formed of a refrigerant pipe, and the inlet (16) is provided at a position corresponding to the first spiral chamber (13) on the side surface of the casing (2), and the outlet (17) is It is provided at a position corresponding to the upper side of the motor chamber (6) on the side surface of the casing (2).

A second communication path (18) for guiding the refrigerant in the motor chamber (6) to the suction side of the second impeller chamber (92) is connected to a side surface of the casing (2). The second communication passage (18) is also the first
Like the communication passage (15), the communication passage (15) is constituted by a refrigerant pipe.
The inlet (19) of the second communication path (18) is provided at a position corresponding to the lower side of the motor chamber (6) on the side surface of the casing (2), and the outlet (20) of the second communication passage (18) is It is provided at the center of the lower end surface. The second communication passage (18) directs the refrigerant in the motor chamber (6) from the lower side of the second impeller (9) to the second impeller chamber (92) along the axial direction of the second impeller (9). Leading.

The second spiral chamber on the side surface of the casing (2)
At a position corresponding to (14), a discharge pipe (21) extending horizontally is provided outside the casing (2). Second spiral chamber (14)
A discharge passage (96) is formed between the discharge pipe (21). The discharge pipe (21) discharges the refrigerant discharged into the second spiral chamber (14) to outside the casing (2). That is, the second impeller
With the rotation of (9), from the second communication passage (18) to the second impeller chamber
The refrigerant sucked into the (92) flows outward in the radial direction into the second spiral chamber (14), is collected in the second spiral chamber (14), and is discharged through the discharge passage (96). It is configured to be discharged to the pipe (21).

The motor chamber (6) houses a motor (22) for rotating and driving the first impeller (8) and the second impeller (9). The motor (22) is arranged concentrically with the impellers (8) and (9) housed inside the stator (23) fixed to the inner wall surface of the motor chamber (6) and the stator (23). Rotor
(24). The stator (23) and the rotor (24)
It constitutes the motor body. The rotor (24) is fixed at its center to a drive shaft (10) extending vertically.

The upper and lower sides of the drive shaft (10) are first bearing plates.
(25) and a second bearing plate (26), rotatably supported by the casing (2). Specifically, the upper end of the drive shaft (10) is formed in a through hole formed in the center of the first bearing plate (25).
(27), and the lower end of the drive shaft (10) is
It is inserted through a through hole (28) formed in the center of (26).

The outer peripheral surfaces of the upper end and the lower end of the drive shaft (10) are provided with herringbone grooves (29,
29, ...) are formed. That is, as shown in FIG. 4, two rows of herringbone grooves (29, 29,...) Are formed vertically at the upper end and the lower end of the drive shaft (10). The herringbone grooves (29, 29, ...) are formed in a shape that is twisted in the rotation direction X from the inner end toward the outer end.

The herringbone grooves (29, 29,...)
When the is rotated, the outer peripheral surface of the drive shaft (10) and the through holes (27), (28)
Is formed so as to generate a gas film by a gas pressure in a gap between the inner peripheral surface and the inner peripheral surface. With this gas film, the drive shaft
Dynamic pressure gas bearing (3) supporting the lower end of (10) in a non-contact state
5) is configured. That is, the dynamic pressure gas bearing (35) is a so-called herringbone journal gas bearing, and rotatably supports the lower end of the drive shaft (10).

The drive shaft (10) has a large-diameter portion (31) located at the center of the casing (2) and the impellers (8), (9) (32), (32)
It is composed of The upper and lower ends of the large diameter portion (31) are the first
The through hole (27) of the bearing plate (25) and the through hole (28) of the second bearing plate (26) are inserted.

A thrust bearing plate (33) is provided between the second bearing plate (26) and the lower partition (4). At the center of the thrust bearing plate (33), the small diameter part of the drive shaft (10)
A through hole (34a) having substantially the same diameter as (32) is formed. The inner surface of the through hole (34a) and the outer peripheral surface of the small diameter portion (32) are connected, and the drive shaft (10) and the thrust bearing plate (33) are integrally fixed.

The lower surface of the thrust bearing plate (33) is a lower partition.
The upper surface of the thrust bearing plate (33) faces the lower surface of the second bearing plate (26). Although not shown, substantially spiral spiral grooves forming a thrust-side pressure raising mechanism are formed on both upper and lower surfaces of the thrust bearing plate (33). Due to the action of the spiral groove, upward and downward thrusts are provided between the thrust bearing plate (33) and the lower partition (4) and between the thrust bearing plate (33) and the second bearing plate (26). A dynamic pressure gas bearing (34) constituting a bearing is configured. The drive shaft (10) is supported in the thrust direction by the dynamic pressure gas bearing (34).

-Operation of Building Multi-Air Conditioner (50)-The operation of the building multi-air conditioner (50) will be described. First, a cooling operation for cooling each room will be described.

During the cooling operation, the four-way switching valve (54)
Is switched to the solid line side shown in FIG. Also, a circulation path of the refrigerant is formed by an electromagnetic valve or the like (not shown) such that the refrigerant circulates only in the indoor unit (52) in which the switch is turned on (the switch is in an ON state).

In the above state, the compressor (1) in each outdoor unit (51) is started.

At this time, since the compressor can be operated at the maximum capacity from the start of the operation, the cooling of each room can be performed quickly. Therefore, the problem such as the problem 3 (comfort) described above does not occur.

[0086] The refrigerant discharged from the compressor (1) passes through the four-way switching valve (54) and is condensed in the outdoor heat exchanger (56a). At this time, since only the refrigerant flows in the pipe of the outdoor heat exchanger (56a), the heat transfer of the refrigerant is good. Therefore, the problem such as the problem 7 (adhesion of lubricating oil to the heat exchanger and the pipe) does not occur.

After the pressure of the refrigerant is reduced by the pressure reducing mechanism (55), the refrigerant flows out of the outdoor unit (51). At this time, assignment 9
A problem such as (blockage of the pressure reducing mechanism) does not occur.

The refrigerant flowing out of the outdoor unit (51) flows through the refrigerant pipe (53) toward each indoor unit (52). At this time, the refrigerant flows in the middle of the refrigerant pipe (53) located between the outdoor unit (51) and the indoor unit (52).
The flow is divided by an electromagnetic valve or the like (not shown) according to the cooling load of each room.

In the multi air conditioner (50) for the building, the refrigerant pipe (53) connects the outdoor unit (51) installed on the roof and the indoor unit (52) installed in each room. Very long in length. However, since the turbo compressor (1) that does not use lubricating oil is used, problem 1 (retention of lubricating oil)
There is no problem such as or problem 6 (oil return).

Then, after being separated, the indoor unit (52)
Refrigerant flowing into the indoor evaporator in the indoor heat exchanger (56b). As a result, the indoor air is cooled by exchanging heat with the refrigerant,
Indoor cooling is performed.

Thereafter, the refrigerant evaporated in the indoor heat exchanger (56b) flows out of the indoor unit (52), and flows out of the outdoor unit (51).
To the inside of the refrigerant pipe (53).

Then, the refrigerant flows into the outdoor unit (51), passes through the four-way switching valve (54), and is sucked into the compressor (1). At this time, a problem such as the problem 4 (oil compression) does not occur.

As described above, the refrigerant circulates through the refrigerant circuit of the multi air conditioner for building (50), and the rooms of the building (60) are cooled.

On the other hand, in the heating operation, the four-way switching valve (5
4) is switched to the broken line side shown in FIG. Then, the refrigerant discharged from the compressor (1) circulates in the refrigerant circuit (5A) in a direction opposite to that in the cooling operation. That is, the refrigerant discharged from the compressor (1) is condensed in the indoor heat exchanger (56b),
(55), evaporates in the outdoor heat exchanger (56a),
Perform circulation returning to (1). As a result, the indoor air is heated by the condensation heat of the refrigerant in the indoor heat exchanger (56b), and the room is heated.

-Operation of Compressor (1)-Next, the operation of the compressor (1) will be described.

First, during the compression operation, the motor (22) is driven, and the drive shaft (10) rotates at high speed. And this drive shaft
According to the rotation of (10), the first impeller (8) and the second impeller
(9) rotates at high speed in the first impeller chamber (91) and the second impeller chamber (92).

At this time, the gap between the outer peripheral surface of the upper end of the large diameter portion (31) of the drive shaft (10) and the inner peripheral surface of the first bearing plate (25), and the lower end of the large diameter portion (31) In the gap between the outer peripheral surface and the inner peripheral surface of the second bearing plate (26), a gas film is formed by gas pressure, and a dynamic pressure gas bearing (35) is formed. Due to this gas film, the drive shaft (10) is connected to the first bearing plate (25) and the second bearing plate (2).
6) is supported in the radial direction without contact.

The gap between the thrust bearing plate (33) and the second bearing plate (26) and the gap between the thrust bearing plate (33) and the lower partition (4) are filled with gas by gas pressure. A film is formed and a dynamic pressure gas bearing (34) is formed. The drive shaft (10) is supported in the thrust direction by the gas film.

The first impeller in the first impeller chamber (91)
By the rotation of (8), the refrigerant is sucked into the first impeller chamber (91) from the suction pipe (12). The refrigerant guided to the first impeller (8) along the axial direction of the first impeller (8) is supplied to the first impeller (8).
It flows outward in the radial direction along the blade (11) and flows out from the outer peripheral end of the first impeller (8). At this time, the refrigerant is
The dynamic pressure and the static pressure are obtained by the centrifugal force given by the impeller (8) and pass through the diffuser (101). In the diffuser (101), the refrigerant decelerates, the dynamic pressure is converted to static pressure, and the dynamic pressure is recovered. Then, the refrigerant is pressurized and discharged to the first spiral chamber (13). Thereafter, the refrigerant flows into the first spiral chamber (13).
Flows through the first communication path (15) and flows into the motor chamber (6).

The refrigerant in the motor chamber (6) is supplied to the second impeller chamber (9).
Due to the rotation of the second impeller (9) in 2), the second communication passage
It is sucked from (18) and sucked into the second impeller chamber (92).
The refrigerant guided to the second impeller (9) along the axial direction of the second impeller (9) flows outward in the radial direction along the blades (11) of the second impeller (9). It flows out from the outer peripheral end of (9). Thereafter, in the same manner as in the compression operation in the first impeller chamber (91), the refrigerant is pressurized and discharged to the second spiral chamber (14), and is discharged as high-pressure gas from the discharge pipe (21).

-Effects of Building Multi-Air Conditioner (50)-As described above, the building multi-air conditioner (50)
(1) Gas bearings (34, 35) are used, and impeller chambers (91), (9
2) No airtightness is required, so no lubricating oil is required.

Therefore, the seizure of the compressor due to lack of lubricating oil in the compressor does not occur, and the reliability is high.

Further, since there is no problem of poor lubrication due to a decrease in the viscosity of the lubricating oil, the reliability is high.

Further, since there is no problem of forming the lubricating oil, the compressor (1) can be operated at the maximum capacity from the start. Therefore, each room can be quickly brought to the predetermined temperature. Therefore, the multi air conditioner for this building (50)
It is possible to perform air conditioning with high comfort. Furthermore,
Since no special control for startup is required, the configuration can be made at low cost.

Further, since there is no fear of oil compression in the compressor, the reliability is high.

Further, since it is not necessary to return the oil, the length of the pipe can be increased. Therefore, large buildings such as high-rise buildings can be air-conditioned with only a single device (50). Further, there is an effect that the degree of freedom in installing the outdoor unit and the outdoor unit is increased.

The pressure loss of the refrigerant pipe (53) is reduced as compared with the case where lubricating oil is used. Therefore, the compressor (1)
Load is reduced, and efficiency is improved.

Further, since there is no need to select a lubricating oil according to the alternative refrigerant, design and development can be shortened.

Further, the pressure reducing mechanism (55) is not blocked by the fatty acid in the ester oil.

As described above, in the refrigerating apparatus of the present embodiment,
Since an oilless compressor is used as the compressor (1), various problems associated with lubricating oil do not occur. Therefore, the present invention provides a configuration particularly suitable for a multi-air conditioner for buildings (50),
As a result, highly reliable and comfortable air conditioning can be realized at low cost.

Further, in the multi air conditioner (50) for the building, not only the compressor (1) is made oil-less but also a two-stage turbo compressor, so that the following effects are obtained.

First, as shown in FIG. 5, the air-conditionable area becomes large. In other words, if it is a single-stage turbo compressor,
If HFC134a or R410A is used as a refrigerant and it is attempted to secure a large difference between the high and low pressures in the refrigerant circuit, measures such as increasing the diameter of the impeller and increasing the rotation speed of the impeller are required. There were problems such as the generation of shock waves around the impeller. Therefore, with the single-stage turbo compressor, air conditioning could be performed only within the operating area below the solid line S. However,
In the multi air conditioner (50) for this building, the operable area has been expanded by setting the number of stages of the turbo compressor (1) to two. Specifically, air conditioning can be performed in an operation area below a solid line D located above the solid line S. As a result, it is possible to cover not only the cooling operation area C required for the cooling operation but also the heating operation area H required for the heating operation. Therefore, the multi air conditioner (50) for the building can perform not only the cooling operation but also the heating operation.

On the other hand, when a refrigerant having a relatively large gas constant, for example, carbon dioxide, is used as the refrigerant, the generation of shock waves around the impeller is suppressed. Can be increased. Therefore, even with a single-stage turbo compressor, it is possible to expand the operation area and cover the heating operation area. However, in this case, the high pressure of the refrigerant circuit becomes a very high pressure,
It is necessary to ensure a high pressure resistance of the refrigerant pipe and the heat exchanger. For this reason, the cost is increased, and the size and the weight are sometimes increased. However, the multi-air conditioner (50) for the building uses the two-stage turbo compressor (1), so that such a problem can be avoided.

As described above, since the high compression ratio required for the heating operation can be realized, the outer peripheral speed of the impeller can be relatively reduced during the cooling operation, and the turbo compressor can be used. Thus, it is possible to suppress the shock wave around the impeller, which is a factor of lowering the overall efficiency of the compressor, and to improve the overall efficiency of the compressor as compared with the related art.

Further, the refrigerant compressed by the first impeller (8) is once led to the motor chamber (6), and then the second impeller
Since compression is performed in (9), the pressure difference between the first impeller chamber (91) and the motor chamber (6) and the second impeller chamber (92)
The pressure difference between the motor chamber (6) and the motor chamber (6) becomes relatively small. Therefore, refrigerant leakage between the first impeller chamber (91) and the motor chamber (6) and refrigerant leakage between the second impeller chamber (92) and the motor chamber (6) can be reduced. Thus, the efficiency of the compressor (1) can be improved.

<Embodiment 2> Embodiment 2 is based on Embodiment 1.
In this embodiment, the compressor (1) is replaced with a turbo compressor (1a) shown in FIG.

The compressor (1a) is configured not to guide the refrigerant in the first spiral chamber (13) to the motor chamber (6), but directly to the second impeller chamber (92). That is, the communication passage (15a)
The inlet (16) is provided at a position corresponding to the first spiral chamber (13) on the side surface of the casing (2), and the outlet (20) of the communication passage (15a) is provided at the lower end face of the casing (2). It is formed at the center.

The suction pipe (12) and the motor chamber (6) are connected to the equalizing pipe (3
6). The internal pressure of this equalizing pipe (36) is
It changes according to the rotation speed of the first impeller (8). Equalizing tube (3
6) returns the leaked fluid (refrigerant) from the second impeller chamber (92) to the motor chamber (6) to the suction pipe (12).

<Embodiment 3> Embodiment 3 is based on Embodiment 1.
, The compressor (1) is replaced with a turbo compressor (1b) shown in FIG.

The compressor (1b) comprises a first impeller (8) and a second impeller (8).
The impeller (9) is configured to be stacked vertically above the motor chamber (6) in a state where the suction directions of the respective refrigerants are aligned.

That is, inside the casing (2), the upper partition (3), the intermediate partition (38), the lower partition (4),
A thrust bearing plate (33) and a second bearing plate (26) are provided. A first impeller chamber (91) is formed above the upper partition (3), and a second impeller chamber (92) is formed between the intermediate partition (38) and the lower partition (4). A motor chamber (6) is formed below the second bearing plate (26). The upper partition wall (3) is provided with a communication path (15a) for guiding the refrigerant in the first spiral chamber (13) to the suction side of the second impeller chamber (92). Discharge tube (21)
The outer peripheral surface of the second spiral chamber (14) is located substantially at the center in the vertical direction of the casing (2) so as to discharge the refrigerant in the second spiral chamber (14) through the discharge passage (96). Connected to the corresponding position. As in the second embodiment, a pressure equalizing pipe (36) is provided between the suction pipe (12) and the motor chamber (6).

<Embodiment 4> Embodiment 4 is based on Embodiment 1.
In this embodiment, the compressor (1) is replaced with a turbo compressor (1c) shown in FIG.

The compressor (1c) includes a first impeller (8) and a second impeller (8).
The impeller (9) is configured to be vertically stacked above the motor chamber (6) in a state where the refrigerant suction directions are opposite to each other.

That is, inside the casing (2), the upper partition (3), the intermediate partition (38), the lower partition (4),
A thrust bearing plate (33) and a second bearing plate (26) are provided. Between the lower partition (4) and the intermediate partition (38), a first impeller (8) is provided in a state of diverging downward,
Above the upper partition wall (3), a second impeller chamber (92) is provided so as to diverge upward. Inhalation tube (12)
Is connected to the outer peripheral surface of the casing (2) so as to be continuous with a suction passage (95) formed between the upper partition (3) and the intermediate partition (38). The outlet (41) of the suction passage (95) is
The first impeller chamber (91) formed to partition the impeller chamber (91) and the second impeller chamber (92) is open to the suction side. In other words, the refrigerant sucked from the suction pipe (12)
(95), and is guided to the suction side of the first impeller (8) without leaking into the second impeller chamber (92). The first spiral chamber (13) and the suction side of the second impeller chamber (92) are in communication with each other by a communication passage (15a).
The refrigerant compressed in (13) is further compressed in the second swirl chamber (14). A discharge pipe (21) is connected to the outer peripheral surface of the casing (2) at a position corresponding to the second spiral chamber (14), and high-pressure refrigerant is discharged through the discharge passage (96) and the discharge pipe (21). It has become so.

<Fifth Embodiment> A fifth embodiment is different from the first embodiment.
, The compressor (1) is replaced with a turbo compressor (1d) shown in FIG.

In the compressor (1d), similarly to the compressor (1c) of the fourth embodiment, the first impeller (8) and the second impeller (9) are connected to each other above the motor chamber (6). Are arranged in the vertical direction in a state where they are reversed, but the installation direction of each impeller (8), (9) is different from that of the fourth embodiment.

That is, the first impeller (8) is provided in a state of diverging downward, and the second impeller (9) is provided in a state of diverging upward. casing
Inside (2), the upper bulkhead (3) and the middle bulkhead (3
8), a lower partition (4), a thrust bearing plate (33), and a second bearing plate (26) are provided. Upper bulkhead (3) and middle bulkhead (38)
A second impeller chamber (92) is formed between
A first impeller chamber (91) is formed between (8) and the lower partition (4). The suction pipe (12) is connected to the outer peripheral surface of the casing (2) so as to be continuous with a suction passage (95) formed between the lower partition (4) and the thrust bearing plate (33). Above the upper partition wall (3), a communication path (15a) for guiding the refrigerant from the first spiral chamber (13) to the second impeller chamber (92) is formed. The suction pipe (12) and the motor chamber (6) are connected by a pressure equalizing pipe (36).

Therefore, the refrigerant sucked from the suction pipe (12) flows into the first impeller chamber (91) from the suction passage (95), is compressed in the first spiral chamber (13), and then is compressed. The air flows into the second impeller chamber (92) through 15a), is compressed in the second spiral chamber (14), and is discharged from the discharge pipe (21) through the discharge passage (96).

<Sixth Embodiment> A sixth embodiment is different from the first embodiment.
, The compressor (1) is replaced with a three-stage turbo compressor (1e) shown in FIG.

[0130] Inside the casing (2) of the compressor (1e),
In order from the top, upper partition (3), partition (45), partition (46), first
A thrust bearing plate (33), a first bearing plate (25), a second bearing plate (26), a second thrust bearing plate (48), and a lower partition (49) are provided. Inside the casing (2), in order from the top, a second impeller chamber (92), a second spiral chamber (14) located around the second impeller chamber (92), and a third impeller chamber (93) And a third spiral chamber (9) located around the third impeller chamber (93).
4), the motor chamber (6), the first impeller chamber (91) and the first impeller chamber (91).
A first spiral chamber (13) located around the impeller chamber (91) is provided. The thrust bearing may be either one of the first thrust bearing plate (33) and the second thrust bearing plate (48), and it is not always necessary to provide two.

The first impeller chamber (91) below the lower partition (49)
, The first impeller (8) is provided in an upwardly diverging state. In the second impeller chamber (92) above the upper partition wall (3), the second impeller (9) is provided so as to be divergent downward. In the third impeller chamber (93) between the partition (45) and the partition (46), the third impeller (43)
Are provided in a downwardly divergent state.

The suction pipe (12) is connected to the center of the lower end surface of the casing (2). Suction pipe (12) and first impeller chamber
A suction passage (95) for introducing the suction refrigerant into the first impeller chamber (91) along the axial direction of the first impeller (8) is formed between the suction passage (95) and the suction passage (95).

An upstream side of the first communication path (15) is connected to a position corresponding to the first spiral chamber (13) on the outer peripheral surface of the casing (2). The downstream side of the first communication path (15) is connected to the central portion of the upper end surface of the casing (2), and the refrigerant in the first spiral chamber (13) flows along the axial direction of the second impeller (9). It is configured to lead to the two impeller chamber (92).

The upper partition wall (3) has a second spiral chamber (14) and a third spiral chamber (14).
A second communication passage (18) communicating with the suction side of the impeller chamber (93) is formed. That is, the second communication path (18) is configured to guide the refrigerant in the second spiral chamber (14) to the suction side of the third impeller chamber (93).

A discharge pipe (21) is connected to a position corresponding to the third spiral chamber (94) on the outer peripheral surface of the casing (2). A discharge passage is provided between the third spiral chamber (94) and the discharge pipe (21).
(96) is formed.

The suction pipe (12) and the motor chamber (6) are connected to the equalizing pipe (3
6).

In this compressor (1e), as in the first embodiment, the drive shaft (10) is supported by the gas bearings (34) and (35) in a non-contact state.

In operation, the refrigerant flows into the first impeller chamber (91) from the suction pipe (12) through the suction passage (95), and after the first stage compression is performed, the refrigerant flows into the first spiral chamber (13). And the first communication passage (1
It flows into the second impeller chamber (92) through 5). After the refrigerant is further compressed in the second stage, the pressure of the refrigerant further increases, and then the refrigerant flows into the third impeller chamber (9) through the second spiral chamber (14) and the second communication path (18).
3). The refrigerant is further compressed by the third stage compression, and is discharged from the discharge pipe (21) through the third spiral chamber (94) and the discharge passage (96).

<Embodiment 7> Embodiment 7 is similar to Embodiment 1.
, The compressor (1) is a turbo compressor (1f) shown in FIG.
Is replaced by

In the compressor (1f), in order from the upper part to the lower part in the casing (2), the second impeller chamber (92) and the second spiral chamber () located around the second impeller chamber (92). 14),
A motor chamber (6), a first impeller chamber (91), and a first spiral chamber (13) located around the first impeller chamber (91) are formed. The suction pipe (12) is connected to the center of the casing (2) so as to guide the low-pressure refrigerant to the motor chamber (6), and is connected to the suction passage (12A).
Is formed. The motor chamber (6) and the suction side of the first impeller chamber (91) are connected by a first communication passage (15A).
The first spiral chamber (13) and the suction side of the second impeller chamber (92) are in the second
They are communicated by a communication passage (18A).

After the low-pressure refrigerant sucked through the suction passage (12A) flows into the motor chamber (6), it is guided to the suction side of the first impeller chamber (91) through the first communication passage (15A). This refrigerant is
In the first impeller chamber (91), the refrigerant is compressed by the first impeller (8) to become a medium-pressure refrigerant, and is discharged to the first spiral chamber (13). The intermediate-pressure refrigerant collected in the first spiral chamber (13) flows into the suction side of the second impeller chamber (92) through the second communication passage (18A), is compressed by the second impeller (9), and is compressed by the second impeller (9). And is collected in the second spiral chamber (14). Second spiral chamber (14)
The high-pressure refrigerant inside is discharged from the discharge pipe (21) through the discharge passage (96).

<Eighth Embodiment> An eighth embodiment is different from the first embodiment.
, The compressor (1) is replaced with the turbo compressor (1) shown in FIG.
h). The turbo compressor (1h) is configured by connecting two turbo compressor units (65) and (66) in series so as to compress the refrigerant in two stages.

Since the structure of the first compressor unit (65) and the structure of the second compressor unit (66) are the same, only the structure of the first compressor unit (65) will be described here. )
Is omitted.

In the casing (80A), a partition (81A) is provided at a position having a predetermined dimension from the upper end, and inside the casing (80A), the impeller chamber (82) above the partition (81A) is provided.
A) and a lower motor chamber (83A) are defined.
The impeller chamber (82A) is formed at the center of the casing (80A) in plan view, and has a substantially truncated conical shape whose inner diameter gradually increases downward. Impeller room (8
An impeller (85A) is rotatably housed inside 2A). The impeller (85A) is provided with a plurality of substantially triangular plate blades (84A), (84A),... Radially around a vertical axis. A spiral chamber (86A) is formed around the outer periphery of the impeller (85A) in the impeller chamber (82A).

In the motor chamber (83A), a stator (87A) fixed to the inner wall surface of the motor chamber (83A) and a stator (87A) housed inside and arranged concentrically with the impeller (85A). A motor (89A) including a rotor (88A) is provided. The drive shaft (90A) is fixed to the center of the rotor (88A), and the drive shaft (9
The upper and lower ends of 0A) are rotatably supported by bearing plates (111A) and (112A). Specifically, the lower end of the drive shaft (90A) is longer than the lower end of the rotor (88A), and the through hole (113A) of the lower bearing plate (111A) provided at the lower end of the motor chamber (83A). ). A herringbone groove (114A) is formed on the outer peripheral surface of the lower end of the drive shaft (90A). Then, the rotation of the drive shaft (90A) causes the drive shaft (90A) to rotate.
A gas film is generated by a gas pressure in a gap between the outer peripheral surface of the lower end of A) and the inner peripheral surface of the through hole (113A), and the lower end of the drive shaft (90A) is brought into a non-contact state by this gas film. Supported. That is, the lower end of the drive shaft (90A) is a dynamic pressure gas bearing (117A).
It is rotatably supported by.

On the other hand, the upper end of the drive shaft (90A) is
A) extends above the upper end of (A) and is located below the large diameter part (1
15A) and the impeller (85A) continuously above the large diameter part (115A)
And a small-diameter portion (116A) connected thereto. Large diameter part (1
15A) is rotatably supported by a dynamic pressure gas bearing (117A) similar to the bearing structure at the lower end of the drive shaft (90A) described above. That is, the large diameter portion (115A) is inserted into the through hole (118A) of the upper bearing plate (112A) provided above the motor chamber (83A). In addition, a herringbone groove (119A) is formed on the outer peripheral surface of the large diameter portion (115A), and the rotation of the drive shaft (90A) causes a gap between the outer peripheral surface and the inner peripheral surface of the through hole (118A). A gas film is generated in the gap. Also, on the upper side of the upper bearing plate (112A), a thrust bearing plate (120A)
Is provided. Then, the lower surface of the thrust bearing plate (120A) comes into contact with the upper end surface of the large diameter portion (115A) so that the drive shaft (9
Positioning in the thrust direction of 0A) is performed. In the center of the thrust bearing plate (120A), a through hole (121A) having substantially the same diameter as the small diameter portion (116A) is formed, and the small diameter portion (116A) is supported on the inner surface of the through hole (121A). doing.

Next, the connection relationship between the first compressor unit (65) and the second compressor unit (66) will be described. Inhalation tube (12)
Is connected to the center of the lower end surface of the casing (80B) of the second compressor unit (66), and the refrigerant sucked into the second compressor unit (66) from the suction pipe (12).
It is designed to be introduced into the motor room (83B) of the compressor unit (66). Motor room (83B) in casing (80B)
Between the position corresponding to the upper part of the first compressor unit (65) and the lower end surface of the casing (80A) of the first compressor unit (65), the refrigerant in the motor chamber (83B) of the second compressor unit (66) is supplied to the first compressor unit (66). Compressor unit
A first connection pipe (122) leading to the motor chamber (83A) of (65) is provided. Between the position corresponding to the upper part of the motor chamber (83A) on the side surface of the casing (80A) of the first compressor unit (65) and the center of the upper end surface of the casing (80A) of the first compressor unit (65). Impeller (85A) with the refrigerant in the motor room (83A)
A second connection pipe (123) is provided for introducing the impeller chamber (82A) from above along the rotation axis of the second connection pipe. Swirling chamber (86A) on the side of casing (80A) of first compressor unit (65)
And the center of the upper end surface of the casing (80B) of the second compressor unit (66), the refrigerant compressed by the first compressor unit (65) is rotated by the rotating shaft of the impeller (85B). A third connecting pipe introduced into the impeller chamber (82B) from above along the line
(124) is provided. A discharge pipe (21) is connected to a position corresponding to the spiral chamber (86B) on the side surface of the casing (80B) of the second compressor unit (66).

During operation of the multi air conditioner (50), that is, during operation of the first compressor unit (65) and the second compressor unit (66), the refrigerant sucked from the suction pipe (12) is 2 Flow into the motor room (83B) of the compressor unit (66),
After cooling B), it flows into the first connection pipe (122) from the motor chamber (83B). The refrigerant in the first connecting pipe (122) flows into the motor chamber (83A) of the first compressor unit (65), cools the motor (89A), and then passes through the second connecting pipe (123). unit
It flows into the impeller chamber (82A) of (65). The refrigerant flowing into the impeller chamber (82A) is compressed by the rotation of the impeller (85A), collected in the spiral chamber (86A), and discharged to the third connection pipe (124). That is, by the first compressor unit (65),
The first-stage compression operation is performed, and the pressurized refrigerant is supplied to the third connection pipe.
(124). The refrigerant in the third connection pipe (124) flows into the impeller chamber (82B) of the second compressor unit (66), is compressed by the rotation of the impeller (85B), and is collected in the spiral chamber (86B). That is, by the second compressor unit (66), 2
The compression operation of the stage is performed. Then, the refrigerant in the spiral chamber (86B) is discharged to the discharge pipe (21).

As described above, in this embodiment, since the turbo compressor units (65) and (66) are connected in series and the refrigerant compression operation is performed in two stages, the compression ratio per stage is reduced. Is relatively small. Therefore, the same effect as that of the first embodiment can be obtained, for example, the operable area can be enlarged.

The number of connected turbo compressor units is not limited to two, but may be three or more.

Ninth Embodiment A ninth embodiment is a modification of the seventh embodiment.
And a backflow prevention mechanism for preventing a backflow of the refrigerant inside the compressor immediately after the operation of the turbo compressor (1f) is stopped.

In the turbo compressor, when driven, the inside of the suction pipe is in a low pressure state due to the suction negative pressure. On the other hand, the inside of the discharge pipe is in a high pressure state due to the flow of the compressed refrigerant. Therefore, when the rotation of the impeller is stopped when the turbo compressor is stopped, the inside of the discharge pipe on the downstream side of the impeller on the subsequent stage is more downstream than the inside of the suction pipe on the upstream side of the impeller on the front stage. Is higher pressure. Therefore, a reverse flow occurs in which the high-pressure refrigerant in the discharge pipe is introduced into the suction pipe through the interior of the compressor, and the action of the high-pressure refrigerant causes the impeller to rotate in a direction opposite to the rotation direction of the compression operation described above. Become. As a result, the drive shaft also rotates in the reverse direction. Then, in the reverse rotation state, the bearing function of the dynamic pressure gas bearing is not exhibited, and in some cases, the bearing plate may be seized.

Particularly, in a compressor that performs two or more stages of compression operation, the pressure difference between the high-pressure refrigerant in the discharge pipe and the low-pressure refrigerant in the suction pipe is very large. Therefore, reverse rotation of the drive shaft is more likely to occur than in a single-stage compressor. Therefore, it is very important to prevent reverse rotation of the drive shaft after stopping the operation.

Therefore, as shown in FIG.
In order to prevent the above backflow, the suction pipe (12) and the discharge pipe (2
1), a bypass pipe (71) is provided as a bypass passage. The bypass pipe (71) is provided with an electromagnetic valve (72) as opening / closing means.

When the multi air conditioner (50) is operating, that is, when the turbo compressor (1f) is operating, the solenoid valve (72) is closed. Thereby, as described in the seventh embodiment, the refrigerant is sucked through the suction pipe (12) as shown by the solid line arrow in FIG. 13, and is cooled in two stages by the first impeller (8) and the second impeller (9). It is compressed and discharged through the discharge pipe (21).

On the other hand, when the operation of the turbo compressor (1f) is stopped, the solenoid valve (72) is opened. This allows the bypass pipe (7
The discharge pipe (21) communicates with the suction pipe (12) through 1). As a result, the high-pressure refrigerant in the discharge pipe (21) is directly introduced into the suction pipe (12) through the bypass pipe (71) without flowing backward inside the turbo compressor (1f). Therefore, the pressure inside the discharge pipe (21) and the inside of the suction pipe (12) are equalized immediately after the operation of the turbo compressor (1f) is stopped.

More specifically, immediately after the operation of the turbo compressor (1f) is stopped, the inside of the discharge passage (96) and the inside of the second communication passage (18A)
This is a high-pressure section having a higher pressure than the inside of the first communication passage (15A) or the inside of the motor chamber (6). However, since the discharge pipe (21) and the suction pipe (12) are in communication with each other through the bypass pipe (71), the refrigerant in the high-pressure section does not flow backward as indicated by the dashed arrow in FIG.
It flows through the discharge pipe (21) and the bypass pipe (71) to equalize the pressure with the low pressure part. Therefore, when the operation of the turbo compressor (1f) is stopped, the pressure on the downstream side of the impellers (8) and (9) becomes higher than the pressure on the upstream side, and the impellers (8) and (9) rotate in reverse. Such a situation is avoided.

As described above, in this embodiment, when the operation of the turbo compressor (1f) is stopped, the high-pressure refrigerant in the discharge pipe (21) is introduced into the suction pipe (12) through the bypass pipe (71). The reverse rotation of (8) and (9) is avoided. Therefore, the impeller
(8) The reverse rotation of the drive shaft (10) fixed to (9) is prevented. Therefore, it is possible to avoid a situation in which the drive shaft rotates without performing the bearing function of the dynamic pressure gas bearing due to the reverse rotation of the drive shaft, and the reliability of the turbo compressor (1f) and, consequently, the multi air conditioner (50 ) Reliability is improved.

<Embodiment 10> As shown in FIG. 14, in Embodiment 10, a turbo compressor (1h) of Embodiment 8 is provided with a backflow prevention mechanism similar to that of Embodiment 9.

That is, a bypass pipe (71) provided with an electromagnetic valve (72) is provided between the suction pipe (12) and the discharge pipe (21).

At the time of operation of the turbo compressor (1h),
During operation of the compressor unit (65) and the second compressor unit (66), the solenoid valve (72) is closed. The refrigerant sucked through the suction pipe (12) is compressed by the first compressor unit (65) and the second compressor unit (66) as in Embodiment 8,
Discharged to the discharge pipe (21).

On the other hand, when the operation of the turbo compressor (1h) is stopped, the solenoid valve (72) is opened. Accordingly, the high-pressure refrigerant in the discharge pipe (21) flows through the bypass pipe (71) to the suction pipe (12), and the pressure inside the discharge pipe (21) and the pressure inside the suction pipe (12) are equalized. Immediately after the operation of the turbo compressor (1h) is stopped, the discharge pipe (21),
The inside of the third connecting pipe (124) and the second connecting pipe (123) is a high-pressure part having a higher pressure than the inside of the first connecting pipe (122) and the suction pipe (12). However, in the present embodiment, the pressure in the discharge pipe (21) and the pressure in the suction pipe (12) are equalized.
It circulates in the same direction (forward direction) as the turbo compressor (1h) operates, and its pressure drops. Therefore, the impeller (85A), (8
The occurrence of a backflow that reverses 5B) is avoided.

As described above, also in this embodiment, when the operation is stopped, the high-pressure refrigerant in the discharge pipe (21) is introduced into the suction pipe (12) through the bypass pipe (71).
5) and (66) prevent the impellers (85A) and (85B) from rotating in the reverse direction, and also prevent the drive shafts (10A) and (10B) from rotating in the reverse direction. Therefore, it is possible to avoid a situation in which the drive shaft rotates without performing the bearing function of the dynamic pressure gas bearing, and the reliability of the compressor units (65) and (66) is improved.

In this embodiment, each compressor unit (65),
Instead of providing bypass pipes and solenoid valves for each of (66), a set of bypass pipes (71) and solenoid valves (72) are used to prevent backflow in both compressor units (65) and (66). I have. Therefore, the piping system can be simplified and the cost can be reduced, as compared with a configuration in which each of the compressor units (65) and (66) is provided with a bypass pipe and an electromagnetic valve.

<Eleventh Embodiment> As shown in FIG. 15, the eleventh embodiment differs from the turbo compressor (1f) of the seventh embodiment in that a backflow prevention mechanism for preventing a backflow of the refrigerant immediately after the operation is stopped is provided. This is a mode using stop valves (73) and (74).

The suction pipe (12) is provided with a suction-side check valve (73) as backflow prevention means for permitting only suction of the refrigerant. That is, the suction-side check valve (73) allows the refrigerant flow from the suction pipe (12) to the motor chamber (6), while preventing the refrigerant flow from the motor chamber (6) to the suction pipe (12). It is provided as follows. A discharge-side check valve (74) is attached to the discharge pipe (21) as backflow prevention means that allows only refrigerant discharge. That is, the discharge-side check valve (74) allows the refrigerant flow from the discharge passage (96) toward the discharge pipe (21), while preventing the refrigerant flow from the discharge pipe (21) toward the discharge passage (96). It is provided as follows.

The operation of the turbo compressor (1f) is as described in the seventh embodiment.

When the operation of the turbo compressor (1f) is stopped, the pressure inside the discharge pipe (21) is higher than the pressure inside the suction pipe (12). However, in the present embodiment, a discharge-side check valve (74) for preventing a refrigerant flow from the discharge pipe (21) toward the discharge passage (96) is provided, and further, the motor chamber (6) is connected to the suction pipe (12). Since the suction-side check valve (73) for preventing the refrigerant flow toward
The backflow of the refrigerant due to the pressure difference between the discharge pipe (21) and the suction pipe (12) is reliably avoided. As a result, the reverse rotation of the impellers (8) and (9) is prevented, and the reverse rotation of the drive shaft (10) is also prevented.
Therefore, it is possible to avoid a situation in which the drive shaft rotates without performing the bearing function of the dynamic pressure gas bearing, and the reliability of the turbo compressor (1f) is improved.

The suction-side check valve (73) and the discharge-side check valve (73)
The mode including (74) is the turbo compressor (1f) of the above embodiment.
Not limited to, for example, the turbo compressor of the first to sixth or 8 to 10 (1), (1a), (1b), (1c), (1d), (1e), (1f), (1h)
In addition, a suction check valve (73) and a discharge check valve (74) may be provided.

It is not always necessary to provide both the suction-side check valve (73) and the discharge-side check valve (74), and only one of them may be provided.

<Twelfth Embodiment> A twelfth embodiment relates to a motor
By the drive control of (22), the backflow of the refrigerant when the compressor is stopped is avoided. The configuration of the turbo compressor (1f) according to the present embodiment is the same as that of the above-described seventh embodiment.

In the twelfth embodiment, as shown in FIG.
A controller (131) for controlling the drive of the motor (22) is provided with a stop-time control unit (131). The stop control unit (131)
When the turbocompressor (1f) is stopped, the motor (22) is not stopped immediately, but is configured to perform deceleration control in which the rotation speed is gradually reduced.

The deceleration control of the motor (22) by the stop control section (131) will be described. First, in the driving state of the turbo compressor (1f), a large pressure difference is generated between the inside of the suction pipe (12) and the inside of the discharge pipe (21) according to the rotation speed of the motor (22). Therefore, when the operation of the turbo compressor (1f) is stopped, the motor
If (22) is stopped immediately, due to the above differential pressure,
There is a possibility that the backflow in which the refrigerant in the discharge pipe (21) flows into the suction pipe (12) through the inside of the turbo compressor (1f). Therefore, in the present embodiment, after stopping the operation of the turbo compressor (1f), instead of immediately stopping the rotation of the motor (22),
The number of revolutions is gradually reduced so that the differential pressure becomes equal to or less than a predetermined value. As a result, the pressure difference between the inside of the discharge pipe (21) and the inside of the suction pipe (12) gradually decreases, and this pressure difference becomes a small pressure difference that does not generate a backflow. Then, the operation of the motor (22) is stopped in a state where the differential pressure has become sufficiently small, and the occurrence of the backflow after the stop is avoided. Therefore, reverse rotation of the impellers (8) and (9) is prevented.

As described above, in the present embodiment, the control of the motor (22) when the operation of the turbo compressor (1f) is stopped is improved without changing the structure of the turbo compressor (1f). Reverse rotation of the impellers (8) and (9) can be prevented.

It should be noted that Embodiments 1 to 6 or Embodiments 8 to
Needless to say, the above control may be applied to 11. Even in this case, similarly to the above, the reverse rotation of the impeller is prevented, and the reliability of the turbo compressor is improved.

The bypass pipe (71), the suction-side check valve (73)
The above control may be applied to a turbo compressor provided with a discharge-side check valve (74). By doing so, the backflow of the refrigerant is more reliably prevented.

<Thirteenth Embodiment> A thirteenth embodiment is a modification of the twelfth embodiment in which the control content of the stop control section (131) is changed. The stop control unit (131) of the present embodiment gradually reduces the rotation speed of the motor (22) when the operation of the turbo compressor (1f) is stopped, and when a predetermined low rotation speed is reached, The rotation number is maintained for a predetermined time, and thereafter, control for stopping the motor (22) is executed.

Hereinafter, the stop control of the motor (22) in this embodiment will be described. As shown in FIG.
The solid line 7 is the rotation speed of the impellers (8) and (9), and the broken line is the suction pipe (1).
The pressure difference between the inside of 2) and the inside of the discharge pipe (21) is shown),
In the driving state of the turbo compressor (1f), a large pressure difference is generated between the inside of the suction pipe (12) and the inside of the discharge pipe (21) according to the number of revolutions (region A in FIG. 17). This differential pressure is proportional to the square of the rotation speed of the motor (22), as shown in FIG. For this reason, in the high rotation speed region of the motor (22), the increase in the differential pressure with respect to the increase in the rotation speed is large, and conversely, in the low rotation speed region of the motor (22), the increase in the differential pressure with the increase in the rotation speed increases. Become smaller. By utilizing such characteristics of the turbo compressor (1f), in the present embodiment, when the operation of the turbo compressor (1f) is stopped, first, the rotation speed of the motor (22) is gradually reduced (FIG. 17). In the region B), when the rotation speed reaches a predetermined low rotation speed, the rotation speed is maintained for a predetermined time (region C in FIG. 17). In this state, the differential pressure has almost disappeared, and the motor (22) is stopped in such a state (region D in FIG. 17). Therefore, the motor (2
When the operation is stopped in 2), the pressure difference between the upstream side (inside the suction pipe (12)) and the downstream side (inside the discharge pipe (21)) of the impellers (8) and (9) is extremely small, and the impeller (8 ), When (9) is stopped,
The impellers (8) and (9) do not rotate backward.

As described above, according to the present embodiment, since the stop control is performed in consideration of the characteristics of the turbo compressor (1f), the backflow can be more reliably prevented.

It should be noted that Embodiments 1 to 6 or Embodiments 8 to
Needless to say, the control of this embodiment may be applied to 11. Further, the present control may be applied to a turbo compressor including a bypass pipe (71), a suction-side check valve (73), and a discharge-side check valve (74).

<Other Embodiments> In the above embodiment,
Although the compressor has two or three stages of impellers, the present invention is not limited to these, and may have four or more stages.

The refrigerant may be a mixed refrigerant such as HFC134a or R410A or a single refrigerant such as R22. Further, a natural refrigerant such as CO ₂ may be used.

In the above embodiment, a herringbone journal gas bearing is employed as a bearing for rotatably supporting the drive shaft (10). However, the present invention is not limited to this,
Various gas bearings such as a tilting pad journal gas bearing may be employed.

Each of the impellers (8), (9), and (43) may be an open type or a closed type.

The gas bearing is not limited to the dynamic pressure type by rotating the drive shaft (10), but may be a static pressure type using a refrigerant gas pressure increased by a compressor.

In the above embodiment, with respect to the compressor (1),
Although the gas bearing is used as the bearing, it is sufficient that the drive shaft (10) is rotatably supported in a non-contact state. For example, a magnetic bearing may be used.

In the above embodiment, the air conditioner capable of cooling operation and heating operation has been described. However, the scope of the present invention may be a cooling only device or a heating only device. Of course, it may be a device.

[0188]

As described above, according to the first to tenth aspects, it is possible to overcome the problems inevitably caused by the use of the lubricating oil, to achieve high reliability and comfort, and to reduce the cost. It is possible to provide a simple refrigerating device. Further, since the compression ratio of the refrigerant can be made larger than before, the controllable air conditioning area can be expanded.

According to the eleventh aspect, the above effects can be obtained in a complicated multi-circuit, so that the effects can be more remarkably exhibited.

According to the twelfth to sixteenth aspects, the differential pressure between the inside of the discharge pipe and the inside of the suction pipe when the operation of the turbo compressor is stopped can be reduced, so that the refrigerant inside the turbo compressor can be reduced. Can be prevented, and the reverse rotation of the drive shaft while the function of the gas bearing is not exhibited can be reliably prevented. Therefore, seizure of the drive shaft can be reliably prevented, and the reliability of the refrigeration system is improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a multi air conditioner for a building.

FIG. 2 is a refrigerant circuit diagram of a multi air conditioner for buildings.

FIG. 3 is a longitudinal sectional view of the compressor according to the first embodiment.

FIG. 4 is an enlarged view of a gas bearing.

FIG. 5 is a region diagram showing a operable air-conditioning area.

FIG. 6 is a longitudinal sectional view of a compressor according to a second embodiment.

FIG. 7 is a longitudinal sectional view of a compressor according to a third embodiment.

FIG. 8 is a longitudinal sectional view of a compressor according to a fourth embodiment.

FIG. 9 is a longitudinal sectional view of a compressor according to a fifth embodiment.

FIG. 10 is a longitudinal sectional view of a compressor according to a sixth embodiment.

FIG. 11 is a longitudinal sectional view of a compressor according to a seventh embodiment.

FIG. 12 is a longitudinal sectional view of a compressor according to an eighth embodiment.

FIG. 13 is a longitudinal sectional view of a compressor according to a ninth embodiment.

FIG. 14 is a longitudinal sectional view of a compressor according to a tenth embodiment.

FIG. 15 is a vertical sectional view of a compressor according to an eleventh embodiment.

FIG. 16 is a vertical sectional view of a compressor according to a twelfth embodiment.

FIG. 17 is a diagram illustrating a control operation of the motor according to the thirteenth embodiment.

FIG. 18 is a diagram illustrating a relationship between an impeller rotation speed and a differential pressure between upstream and downstream of the impeller in the turbo compressor.

[Explanation of symbols]

 (1) Compressor (6) Motor chamber (8) First impeller (9) Second impeller (10) Drive shaft (12) Suction pipe (13) First spiral chamber (14) Second spiral chamber (21) Discharge Pipe (29) Herringbone groove (34), (35) Dynamic pressure gas bearing (56a) Outdoor heat exchanger (heat source side heat exchanger) (56b) Indoor heat exchanger (use side heat exchanger) (91) No. 1 Impeller room (92) 2nd impeller room

Claims (16)

[Claims] 1. A turbo compressor (1) for compressing a refrigerant, a heat source side heat exchanger (56a) for condensing or evaporating the refrigerant, and a utilization side heat exchanger (56b) for evaporating or condensing the refrigerant in order. The turbo compressor (1) is connected to form a refrigerant circuit (5A), and the turbo compressor (1) rotates in a non-contact state by a gas bearing (34, 35) provided with a pressure increasing mechanism and the refrigerant. A drive shaft (10) freely supported,
A refrigeration system comprising: a plurality of impellers (8, 9, 43) connected to the drive shaft (10) to compress refrigerant in multiple stages. 2. The refrigeration system according to claim 1, wherein the impeller of the turbo compressor (1) is constituted by a two-stage or three-stage impeller (8, 9, 43). apparatus. 3. The refrigeration system according to claim 2, wherein the turbo compressor (1) includes a first impeller chamber (91) and a first spiral chamber (13) located around the first impeller chamber (91). ), A motor chamber (6), a second impeller chamber (92), and a second spiral chamber (14) located around the second impeller chamber (92) are provided in this order from one end to the other end. A casing (2), a motor body (23, 24) fixed in the motor chamber (6), and a drive shaft extending from the motor body (23, 24) to both the one end and the other end. A motor (22) having the first impeller chamber (91) and a refrigerant sucked from the suction pipe (12).
A suction passage (95) leading to the suction side of the motor, and a drive shaft of the motor (22) in the first impeller chamber (91).
A first impeller (8) connected to the suction passage (95), for sucking the refrigerant from the suction passage (95) from the one end side, compressing the refrigerant, and discharging the compressed air to the first spiral chamber (13); (13) a first communication path (15) for guiding the refrigerant in the motor chamber (6) to the motor chamber (6); and a second communication path for guiding the refrigerant in the motor chamber (6) to the suction side of the second impeller chamber (92). A passage (18) and a drive shaft of the motor (22) in the second impeller chamber (92).
A second impeller (9) that is connected to the second communication passage (10), sucks refrigerant from the second communication passage (18) from the other end side, compresses the refrigerant, and discharges the refrigerant to the second spiral chamber (14); (2) A refrigeration apparatus comprising: a discharge passage (96) for guiding a refrigerant in a spiral chamber (14) to a discharge pipe (21). 4. The refrigeration apparatus according to claim 2, wherein the turbo compressor (1a) includes a first impeller chamber (91) and a first spiral chamber (13) located around the first impeller chamber (91). ), A motor chamber (6), a second impeller chamber (92), and a second spiral chamber (14) located around the second impeller chamber (92) are provided in this order from one end to the other end. A casing (2), a motor body (23, 24) fixed in the motor chamber (6), and a drive shaft extending from the motor body (23, 24) to both the one end and the other end. A motor (22) having the first impeller chamber (91) and a refrigerant sucked from the suction pipe (12).
A suction passage (95) leading to the suction side of the motor, and a drive shaft of the motor (22) in the first impeller chamber (91).
A first impeller (8) connected to the suction passage (95), for sucking the refrigerant from the suction passage (95) from the one end side, compressing the refrigerant, and discharging the compressed air to the first spiral chamber (13); (13) The refrigerant in the second impeller chamber (92)
A communication path (15a) leading to the suction side of the motor, and a drive shaft of the motor (22) in the second impeller chamber (92).
A second impeller (9) connected to the second swirl chamber (14) and sucking the refrigerant from the communication path (15a) from the other end side and compressing and discharging the refrigerant to the second swirl chamber (14); A discharge passage (96) for guiding the refrigerant in the chamber (14) to the discharge pipe (21), and a pressure equalizing pipe communicating the suction pipe (12) and the motor chamber (6).
(36) A refrigeration apparatus comprising: 5. The refrigeration apparatus according to claim 2, wherein the turbo compressor (1b) includes a first impeller chamber (91) and a first spiral chamber (13) located around the first impeller chamber (91). ), A second impeller chamber (92) and a second spiral chamber (14) located around the second impeller chamber (92).
A casing (2) in which a motor chamber (6) is sequentially provided from one end to the other end; a motor body (23, 24) fixed in the motor chamber (6); and a motor body (23 , 24), the drive shaft (10) extending to the one end side.
A first impeller chamber (91), and a motor (22) having
A suction passage (95) leading to the suction side of the motor, and a drive shaft of the motor (22) in the first impeller chamber (91).
A first impeller (8) connected to the suction passage (95), for sucking the refrigerant from the suction passage (95) from the one end side, compressing the refrigerant, and discharging the compressed air to the first spiral chamber (13); (13) The refrigerant in the second impeller chamber (92)
A communication path (15a) leading to the suction side of the motor, and a drive shaft of the motor (22) in the second impeller chamber (92).
A second impeller (9) connected to the second spiral chamber (10) for sucking the refrigerant from the communication path (15a) from the one end side and compressing and discharging the refrigerant to the second spiral chamber (14); (14) A discharge passage (96) for guiding the refrigerant in the discharge pipe (21) to the pressure equalizing pipe for communicating the suction pipe (12) with the motor chamber (6).
(36) A refrigeration apparatus comprising: 6. The refrigeration apparatus according to claim 2, wherein the turbo compressor (1c) includes a second impeller chamber (92) and a second spiral chamber (14) located around the second impeller chamber (92). ), A first impeller chamber (91) and a first spiral chamber (13) located around the first impeller chamber (91).
A casing (2) in which a motor chamber (6) is sequentially provided from one end to the other end; a motor body (23, 24) fixed in the motor chamber (6); and a motor body (23 , 24), the drive shaft (10) extending to the one end side.
A first impeller chamber (91), and a motor (22) having
A suction passage (95) leading to the suction side of the motor, and a drive shaft of the motor (22) in the first impeller chamber (91).
A first impeller (8) connected to the suction passage (95), for sucking the refrigerant from the suction passage (95) from the one end side, compressing the refrigerant, and discharging the compressed air to the first spiral chamber (13); (13) The refrigerant in the second impeller chamber (92)
A communication path (15a) leading to the suction side of the motor, and a drive shaft of the motor (22) in the second impeller chamber (92).
A second impeller (9) connected to the second swirl chamber (14) and sucking the refrigerant from the communication path (15a) from the other end side and compressing and discharging the refrigerant to the second swirl chamber (14); A discharge passage (96) for guiding the refrigerant in the chamber (14) to the discharge pipe (21), and a pressure equalizing pipe communicating the suction pipe (12) and the motor chamber (6).
(36) A refrigeration apparatus comprising: 7. The refrigeration apparatus according to claim 2, wherein the turbo compressor (1d) includes a second impeller chamber (92) and a second spiral chamber (14) located around the second impeller chamber (92). ), A first impeller chamber (91) and a first spiral chamber (13) located around the first impeller chamber (91).
A casing (2) in which a motor chamber (6) is sequentially provided from one end to the other end; a motor body (23, 24) fixed in the motor chamber (6); and a motor body (23 , 24), the drive shaft (10) extending to the one end side.
A first impeller chamber (91), and a motor (22) having
A suction passage (95) leading to the suction side of the motor, and a drive shaft of the motor (22) in the first impeller chamber (91).
A first impeller (8) connected to the first swirl chamber (13) for sucking refrigerant from the suction passage (95) from the other end side, compressing the refrigerant, and discharging the compressed air to the first spiral chamber (13); The refrigerant in the chamber (13) is transferred to the second impeller chamber (92).
A communication path (15a) leading to the suction side of the motor, and a drive shaft of the motor (22) in the second impeller chamber (92).
A second impeller (9) connected to the second spiral chamber (10) for sucking the refrigerant from the communication path (15a) from the one end side and compressing and discharging the refrigerant to the second spiral chamber (14); (14) A discharge passage (96) for guiding the refrigerant in the discharge pipe (21) to the pressure equalizing pipe for communicating the suction pipe (12) with the motor chamber (6).
(36) A refrigeration apparatus comprising: 8. The refrigeration apparatus according to claim 2, wherein the turbo compressor (1e) includes a second impeller chamber (92) and a second spiral chamber (14) located around the second impeller chamber (92). ), A third impeller chamber (93) and a third spiral chamber (94) located around the third impeller chamber (93).
And a motor chamber (6), a first impeller chamber (91), and a first spiral chamber (13) located around the first impeller chamber (91) are sequentially provided from one end to the other end. A casing (2), a motor main body (23, 24) fixed in the motor chamber (6), and a drive shaft extending from the motor main body (23, 24) to both the one end and the other end. A motor (22) having a suction pipe (12) and a refrigerant sucked from the suction pipe (12);
A suction passage (95) leading to the suction side of the motor, and a drive shaft of the motor (22) in the first impeller chamber (91).
A first impeller (8) connected to the first swirl chamber (13) for sucking refrigerant from the suction passage (95) from the other end side, compressing the refrigerant, and discharging the compressed air to the first spiral chamber (13); The refrigerant in the chamber (13) is transferred to the second impeller chamber (92).
A first communication path (15) leading to the suction side of the motor; and a drive shaft of the motor (22) in the second impeller chamber (92).
A second impeller (9) that is connected to the first communication path (10), sucks refrigerant from the first communication path (15) from the one end side, compresses the refrigerant, and discharges the refrigerant to the second spiral chamber (14); The refrigerant in the spiral chamber (14) is supplied to the third impeller chamber (93).
A second communication passage (18) leading to the suction side of the motor, and a drive shaft of the motor (22) in the third impeller chamber (93).
A third impeller (43) that is connected to the second communication path (10), sucks refrigerant from the second communication path (18) from the one end side, compresses the refrigerant, and discharges the refrigerant to the third spiral chamber (94); A discharge passageway (96) for guiding the refrigerant in the spiral chamber (94) to a discharge pipe (21), and a pressure equalizing pipe communicating the suction pipe (12) and the motor chamber (6).
(36) A refrigeration apparatus comprising: 9. The refrigeration apparatus according to claim 2, wherein the turbo compressor (1f) includes a second impeller chamber (92) and a second spiral chamber (14) located around the second impeller chamber (92). ), A motor chamber (6), a first impeller chamber (91), and a first spiral chamber (13) located around the first impeller chamber (91) are sequentially provided from one end to the other end. A casing (2), a motor body (23, 24) fixed in the motor chamber (6), and a drive shaft extending from the motor body (23, 24) to both the one end and the other end. (10), a suction passage (12A) for guiding refrigerant sucked from a suction pipe (12) to the motor chamber (6), and a refrigerant in the motor chamber (6) to the first chamber. A first communication path (15A) leading to the suction side of the impeller chamber (91), and a drive shaft of the motor (22) in the first impeller chamber (91).
A first impeller (8) that is connected to the first communication path (10), sucks refrigerant from the first communication path (15A) from the other end side, compresses the refrigerant, and discharges the refrigerant to the first spiral chamber (13); The refrigerant in one spiral chamber (13) is transferred to the second impeller chamber (92).
A second communication passage (18A) leading to the suction side of the motor, and a drive shaft of the motor (22) in the second impeller chamber (92).
A second impeller (9) that is connected to the second communication path (10), sucks refrigerant from the second communication path (18A) from the one end side, compresses the refrigerant, and discharges the refrigerant to the second spiral chamber (14); A refrigerating apparatus comprising: a discharge passage (96) for guiding a refrigerant in a spiral chamber (14) to a discharge pipe (21). 10. A turbo compressor (1h) for compressing a refrigerant,
A heat source side heat exchanger (56a) for condensing or evaporating the refrigerant,
A use side heat exchanger (56b) for evaporating or condensing the refrigerant is connected in order to form a refrigerant circuit (5A), and the turbo compressor (1h) is connected in series so as to compress the refrigerant in multiple stages. Multiple turbo compressor units (65,6
6), the drive shaft (90A, 90B) of each of the turbo compressor units (65, 66)
Is provided with a pressure raising mechanism (114A, 114B, 119A, 119B), and is rotatable in a non-contact state by a gas bearing (117A, 117B) formed by the pressure raising mechanism (114A, 114B, 119A, 119B) and a refrigerant. A refrigeration device characterized by being configured to be supported by a refrigerator. 11. The refrigeration apparatus according to claim 1, wherein the refrigerant circuit (5A) is configured as a multi-circuit in which a plurality of use-side heat exchangers (56b) are connected in parallel with each other. A refrigeration apparatus characterized by being performed. 12. The bypass device according to claim 1, wherein the discharge pipe (21) and the suction pipe (12) are connected by bypassing the turbo compressor (1f, 1h). A passage (71) provided in the bypass passage (71);
While the bypass passage (71) is closed during the compression operation of the (f, 1h), the inside of the discharge pipe (21) and the suction pipe (12) are stopped when the compression operation of the turbo compressor (1f, 1h) is stopped. Opening / closing means (7) for opening the bypass passage (71) so as to eliminate the pressure difference with the inside of the
2) A refrigeration apparatus comprising: 13. The refrigerating apparatus according to claim 1, wherein the discharge pipe (21) has a backflow preventing means for permitting only discharge of the refrigerant from the turbo compressor (1f, 1h). A refrigeration apparatus comprising (74). 14. The refrigeration apparatus according to claim 1, wherein the suction pipe (12) has a backflow prevention means that allows only suction of refrigerant to the turbo compressor (1f, 1h). A refrigeration apparatus comprising (73). 15. The refrigeration apparatus according to claim 1, wherein when the operation of the turbo compressor (1f, 1h) is stopped, the inside of the discharge pipe (21) and the inside of the suction pipe (12). After the motor (22) of the turbocompressor (1f, 1h) is gradually decelerated so that the pressure difference between the motor and the turbo compressor (1f, 1h) becomes equal to or less than a predetermined value, stop-time control means (131) for stopping the motor (22)
A refrigeration apparatus comprising: 16. The refrigeration apparatus according to claim 1, wherein when the operation of the turbo compressor (1f, 1h) is stopped, the turbo compressor is stopped.
After gradually lowering the rotation speed of the motor (22) of (1f, 1h),
Stop time control means for maintaining the rotation speed at a predetermined low rotation speed near zero for a predetermined time and thereafter stopping the motor (22)
A refrigeration apparatus comprising (131).