JP2000240596A - Turbo compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the seizure caused by the thermal expansion of a rotary shaft and to improve the performance and the reliability of a multistage turbo compressor using a gas bearing. SOLUTION: The impellers 15, 75 at low stage side and high stage side are respectrively attached to both ends of a rotary shaft 13. First and second inlet passages 141, 142 are mounted for distributing the intake coolant from an intake pipe 130. The blow passages 50a, 50a for blowing the intake coolant of low temperature to the neighborhood of the herringbone grooves 35, 95 of the rotary shaft 13 forming a gas bearing between the static side journal bearings 31, 33 are connected to the inlet passages 141, 142. A groove 53 for heat radiation, is formed on an outer peripheral surface of the rotary shaft 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo compressor, and more particularly, to a turbo compressor having impellers on both sides of a rotating shaft to compress gas in multiple stages.

[0002]

2. Description of the Related Art For example, as disclosed in Japanese Patent Application Laid-Open No. Hei 5-223090, there is known a turbo compressor which compresses a refrigerant in multiple stages by a plurality of impellers mounted on both sides of a rotating shaft. Here, various types of bearings have been proposed as bearings that rotatably support a rotating shaft. However, there are various problems when a bearing that requires lubricating oil is employed. That is, first, since lubricating oil is mixed in the refrigerant, a separate oil separator is required, the configuration becomes complicated, and the cost increases. Further, since lubricating oil is mixed in the refrigerant, there is a problem that the efficiency of the refrigerating device is reduced when the refrigerating device is mounted on the refrigerating device.

Therefore, there is a turbo compressor using a so-called non-contact type gas bearing as a bearing to eliminate the need for lubricating oil and to solve various problems caused by oil.

A gas bearing lubricates a gas film generated in a clearance between a rotating shaft and a bearing portion as the rotating shaft rotates. To maintain good bearing performance, a clearance is required. It is important to keep at an appropriate value.

[0005]

However, in conventional turbo compressors, the rotating shaft is often overheated due to bearing friction or leakage of high-temperature and high-pressure refrigerant after compression, and the temperature rises to cause thermal expansion in many cases. . However, when the rotating shaft undergoes thermal expansion, the clearance between the rotating shaft and the bearing decreases,
Seizure may occur. On the other hand, in order to prevent such seizure, it is conceivable to set the clearance to a large value in advance in consideration of the thermal expansion of the rotating shaft.
In this case, when the temperature rise of the rotating shaft is small at the start of operation or the like, the clearance is too large and it is difficult to sufficiently exert the bearing performance. Therefore, it has been difficult to say that the conventional turbo compressor sufficiently satisfies both performance and reliability.

Particularly, in a multi-stage turbo compressor, the pressure difference of the refrigerant in the compressor tends to be larger than that in a single-stage type, and heat generation due to bearing friction and leakage of the refrigerant in the impeller chamber may occur. Is over several places.
For this reason, it has been considered that it is more difficult to prevent seizure while maintaining the bearing performance than a single-stage compressor due to the characteristics unique to such a multi-stage turbo compressor.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object of the present invention is to provide a multi-stage turbo compressor in which the thermal expansion of a rotating shaft is suppressed and the clearance of a gas bearing is appropriately maintained. And to improve both performance and reliability.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is to simultaneously cool a plurality of portions of a rotating shaft with a low-temperature suction gas.

More specifically, a turbo compressor according to the present invention is a turbo compressor that compresses and discharges intake gas in multiple stages, and includes at least a motor chamber (11) and both sides of the motor chamber (11). A casing (1) defining the first and second impeller chambers (111, 112); a motor (27) housed in the motor chamber (11); and a rotating shaft (13) connected to the motor (27). )
And first and second impellers (15, 75) provided on both sides of the rotating shaft (13) and accommodated in the first and second impeller chambers (111, 112), respectively, and the first and second impellers. Impeller (15,7
5) first and second gas bearing forming portions (35, 95) formed on both sides of the rotating shaft (13), and the first and second gas bearing forming portions of the rotating shaft (13). Parts (35, 95) so as to form gas bearings (37, 97) with the respective parts (35, 95).
And a predetermined clearance (C1, C2), a bearing portion (31, 33) for supporting the rotating shaft (13) in a non-contact state, and the motor chamber (11) To cool the
A suction passage (141, 142) for guiding the suction gas to the motor chamber (11) is provided.

According to the above, low-temperature suction gas before pressure increase is introduced into the motor chamber (11) through the suction passages (141, 142), and the rotating shaft (13) is cooled by the suction gas. Therefore, thermal expansion of the rotating shaft (13) is suppressed, and the clearances (C1, C2) between the rotating shaft (13) and the bearing portions (31, 33) are maintained at appropriate values. Therefore, bearing performance is maintained and seizure is prevented, and performance and reliability are improved.

The above-mentioned intake passage is configured to cool the first and second gas bearing forming portions (35, 95) of the rotating shaft (13) so as to cool the suction gas to the respective gas bearing forming portions of the rotating shaft (13). A plurality of blowing passages (50a) for blowing near (35, 95) may be provided.

According to the above-mentioned matter, the low-temperature intake gas is supplied to the rotating shaft.
Since it is directly blown to the vicinity of each gas bearing forming portion (35, 95) of (13), each gas bearing forming portion (35, 95) is efficiently cooled, and thermal expansion is effectively suppressed.

Further, another turbo compressor according to the present invention includes:
A turbocompressor that compresses and discharges intake gas in multiple stages, comprising a casing (11) having at least a motor chamber (11) and first and second impeller chambers (111, 112) formed on both sides of the motor chamber (11). 1), a motor (27) housed in the motor chamber (11), and a rotating shaft (13) connected to the motor (27),
Provided on both sides of the rotating shaft (13) and the first and second
First and second impellers (15, 75) respectively housed in impeller chambers (111, 112), and both sides of the rotation shaft (13) corresponding to the first and second impellers (15, 75). A gas bearing (3) is provided between the first and second gas bearing forming portions (35, 95) formed and the first and second gas bearing forming portions (35, 95) of the rotating shaft (13).
7, 97) to form the respective gas bearing forming portions (35, 95) and predetermined clearances (C1, C2).
The bearings (31, 33) supporting the (13) in a non-contact state, and the first and second gas bearing forming portions (35, 95) of the rotating shaft (13) are cooled by the suction gas before the pressure increase. As described above, a plurality of blowing passages (50a) for blowing the suction gas to the vicinity of the respective gas bearing forming portions (35, 95) of the rotating shaft (13) are provided.

According to the above, the low-temperature suction gas before pressure increase is blown through the blowing passage (50a) to the vicinity of each gas bearing forming portion (35, 95) of the rotating shaft (13). 35,95) is cooled efficiently and thermal expansion is effectively suppressed. Therefore, the clearances (C1, C2) between the rotating shaft (13) and the bearing portions (31, 33) are maintained at appropriate values. Therefore, bearing performance is maintained and seizure is prevented, and performance and reliability are improved.

The spray passage (50a) is provided with
It may be formed so as to be sprayed obliquely to the axial direction of (13).

According to the above, the suction gas is blown in a direction inclined with respect to the axial direction of the rotating shaft (13), so that it is easy to flow along the axial direction. Therefore, the relative speed of the suction gas with respect to the surface of the rotation shaft (13) increases, and the time during which the suction gas contacts the rotation shaft (13) increases, so that the suction gas and the rotation shaft (13) Heat transfer between the
Cooling of the rotating shaft (13) can be promoted.

The blowing passage (50a) is provided with
It may be formed so as to spray in the tangential direction of (13).

According to the above, the drawn refrigerant easily flows along the circumferential direction of the rotating shaft (13), so that the flow becomes smooth and heat transfer is promoted.

The rotary shaft (13) may have a groove (53) for heat radiation.

According to the above, the heat transfer surface of the rotating shaft (13) is enlarged, and cooling of the rotating shaft (13) is promoted.

Further, another turbo compressor according to the present invention comprises:
A turbo compressor that compresses and discharges intake gas in multiple stages, and is an impeller (1) attached to a rotation shaft (13) of a motor (27).
5a, 75a) and a plurality of compression sections (201, 202),
(13) a plurality of gas bearings (37, 97) provided so as to be pivotally supported at a plurality of locations corresponding to the respective compression portions (201, 202), and the respective gas bearings (37, 97) in the rotating shaft (13). 97), a plurality of blowing passages (20) for blowing the suction gas to the portions (37a, 97a).
3,204).

According to the above-mentioned matter, the low-temperature suction gas before pressurization passes through the respective blowing passages (203, 204) and is blown to the portions (37a, 97a) near the plurality of gas bearings (37, 97) on the rotating shaft (13). . Therefore, thermal expansion of the rotating shaft (13) is suppressed, and seizing of the bearing is prevented. As a result, performance and reliability are improved.

The outlets of the above-mentioned blowing passages (203, 204) are arranged apart from the rotating shaft (13) so as to provide clearances (C1, C2) between the blowing passages (203, 204). Spray passage (204)
May be smaller than the gap between the outlet of the low-stage-side blowing passageway (203) and the rotary shaft (13).

According to the above, the spray passage (204) on the high stage side
Because the outlet of the upper stage is closer to the rotating shaft (13) than the outlet of the blowing passage (203) on the lower stage, the gas bearing (37) on the higher stage
The suction gas is blown more directly in the vicinity (37a) than in the vicinity (97a) of the gas bearing (97) on the lower stage side. Therefore, the portion (37a) near the gas bearing (37) on the high-stage side where thermal expansion is more likely to occur than on the low-stage side becomes easier to cool than the low-stage side, and the degree of thermal expansion of the rotating shaft (13) is reduced. The corresponding cooling is performed. Therefore, efficient cooling is realized.

The blowing passages (203, 204) may be configured such that the blowing passage (204) on the higher stage has a larger spraying amount than the blowing passage (203) on the lower stage.

Due to the above, the portion (37a) in the vicinity of the gas bearing (37) on the high-stage side where thermal expansion is more likely to occur than on the low-stage side becomes easier to cool than the low-stage side, and the rotation shaft (13) Cooling according to the degree of thermal expansion is performed. Therefore, efficient cooling is realized.

The blowing passages (203, 204) blow the suction gas to a portion (97a) of the rotating shaft (13) near the high-stage gas bearing (97), and then collect the gas to form a low-stage gas bearing. It may be configured to spray on the portion (37a) in the vicinity of (37).

According to the above, the low-temperature suction gas is first blown to the portion (97a) near the gas bearing (97) on the high-stage side of the rotating shaft (13). And the high-stage gas bearing
The gas blown to the portion (97a) near (97) is
The vicinity of the high-stage gas bearing (97) in (13) is cooled and the temperature is raised.
Next, the heated gas is recovered, and the low-stage gas bearing (37)
Is sprayed on the vicinity (37a) of the. As a result, the portion near the low-stage gas bearing (37) is also cooled. in this way,
High-stage gas bearing where thermal expansion is more likely to occur than the low-stage side (97)
Because a lower-temperature gas is blown to the portion (97a) near the lower stage gas bearing (97), the portion (97a) near the higher stage gas bearing (97) is closer than the portion (37a) near the lower stage gas bearing (37). Easy to cool. Therefore, cooling according to the degree of thermal expansion of the rotating shaft (13) is performed, and efficient cooling is realized.

[0029]

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

Embodiment 1 FIG. 1 shows a turbo compressor (100) according to an embodiment of the present invention. (1) is a dome-shaped casing. This casing (1) is a bottomed cylindrical casing body (3) with both ends (left and right ends in FIG. 1) opened.
Closing members (5), (65) for covering the opening of the casing body (3)
And are formed in a closed structure.

The turbo compressor (100) is a so-called oilless compressor that does not require lubricating oil, and has a casing (1).
A stationary-side thrust bearing (7) is provided at a position close to the closing member (5). The stationary-side thrust bearing (7) forms a gas bearing with the rotating-side thrust bearing (41). A part of a first stationary journal bearing (31) described later also constitutes a stationary thrust bearing.
That is, both surfaces of the dynamic pressure type thrust gas bearing (43) are dynamic pressure gas bearings. Closure member (5) and stationary thrust bearing
A high-stage impeller chamber (112) is sectioned between (7) and
In the high-stage impeller chamber (112), a substantially frustoconical impeller (impeller) (15) having a plurality of blades (15a) is arranged. On the outer periphery (impeller outlet) of the impeller (15), a diffuser space (9) and a scroll space (17) communicating with the high-stage impeller chamber (112) are formed.

A rotary shaft (13) is rotatably disposed at the center of the casing (1), and the impeller (15) is attached to one end (the left end in FIG. 1) of the rotary shaft (13) so as to rotate integrally. Have been. A slight clearance is provided between the impeller (15) and the closing member (5). In addition, a second supply pipe (136) for guiding the refrigerant to the high-stage impeller chamber (112) is connected to a central portion of the closing member (5). Casing body (3)
A discharge pipe (137) for discharging the pressurized refrigerant is connected to the scroll space (17).

The motor chamber (11) is located at the center of the casing (1).
Are formed, and the middle part of the rotating shaft (13) is arranged so as to be exposed to the internal space of the motor chamber (11). Motor room (1
1) includes a motor (2) including a rotor (23) and a stator (25).
7) is located. The rotor (23) is fixed in the middle of the rotating shaft (13), while the stator (25) faces the rotor (23) such that the peripheral wall member (29) mounted on the inner peripheral surface of the casing body (3). ) Is fixed.

A first stationary journal bearing (31) is fixed to the motor chamber (11) side of the stationary thrust bearing (7), and a second stationary journal bearing (33) is fixed to the opposite side. The first and second stationary journal bearings (31) and (33) and the peripheral wall member (29) form a housing, and the inside of the housing is a motor chamber (11). In addition, these first
The stationary journal bearing (31) and the second stationary journal bearing (33) correspond to the "bearing portion" in the present invention. First and second stationary journal bearings of a rotating shaft (13)
A plurality of herringbone grooves (35), (95) (corresponding to the "gas bearing forming portion") are formed on the outer peripheral surface of the penetrating portion of (31), (33), among these bearings (31), (33). It is formed so as to face the peripheral surface. Further, clearances (C1) and (C2) at predetermined intervals are provided between the rotating shaft (13) and the bearings (31) and (33), and the clearances (C1) and (C2) are provided. Dynamic pressure type journal gas bearings (37) and (97) that rotatably support the rotating shaft (13) in a non-contact state by the gas film formed by the generated gas pressure.

A plate chamber (39) is formed between the stationary side thrust bearing (7) and the first stationary side journal bearing (31).
In this plate chamber (39), a rotating thrust bearing (41) made of a thrust disc is fitted and disposed so as to project outward on the rotating shaft (13). The stationary thrust bearing (7) is disposed closer to the impeller (15) than the rotating thrust bearing (41), and faces the rotating thrust bearing (41). Spiral grooves (not shown) are formed on both surfaces of the rotating thrust bearing (41), and gas generated in a slight clearance between each of the stationary thrust bearing (7) and the first stationary journal bearing (31). A dynamic pressure type thrust gas bearing (43) that rotatably supports the thrust load of the rotating shaft (13) in a non-contact state by the gas film by pressure is configured. The dynamic pressure type thrust gas bearing (43) is disposed closer to the impeller (15) than the dynamic pressure type journal gas bearing (37).

A labyrinth seal portion (45) is provided on the impeller chamber (112) side of the rotary shaft (13) higher than the herringbone groove (35) to prevent refrigerant leakage. A similar labyrinth seal portion (96) is also provided on the low-stage side impeller chamber (111) side.

Second stationary journal bearing (33) and closing member
A low-stage impeller chamber (111) is formed between the lower shaft (65) and the lower-stage impeller chamber (111). Mounted Impeller (75)
Is housed. As with the high-stage impeller chamber (112), the diffuser space (6
9) and the scroll space (77) are arranged to communicate with each other.

The casing body (3) and the peripheral wall member (29) are formed with insertion holes through which first and second suction pipes (131) and (132) formed by branching the suction pipe (130) are inserted. The distal ends of the first and second suction pipes (131) and (132) are inserted into these insertion holes to form first and second suction passages (141) and (142). These suction passages (141) and (142) guide the low-temperature and low-pressure suction refrigerant before pressure increase to the motor room (11), and the compressor (100) has a low-pressure dome structure in which the inside becomes a low-temperature and low-pressure atmosphere. Have.

The casing body (3) and the peripheral wall member (29) on the opposite sides of the first and second suction passages (141) and (142) are connected to the casing (1) from the respective suction passages (141) and (142). The first and second lead-out passages (143), (144) are respectively provided at positions slightly displaced toward the center in the axial direction. These outlet passages (143), (144)
Is a passage for discharging the refrigerant that has cooled the motor (27) and the rotating shaft (13) in the motor chamber (11) from the motor chamber (11). The first and second outlet passages (143) and (144) are connected to the first and second outlet pipes (133) and (134), respectively.
The two outlet pipes (133) and (134) are connected to the central portion of the closing member (65) after being joined to form a first supply pipe (135) for supplying a refrigerant to the low-stage impeller chamber (111). ing.

The second supply pipe (136) is connected to the impeller (7
This is a pipe for supplying the refrigerant pressurized in 5), that is, the refrigerant subjected to the first-stage compression, to the high-stage impeller chamber (112). One end of the second supply pipe (136) is a scroll space (77) on the lower stage side.
The other end is connected to the closing member (5) so as to communicate with the suction side of the high-stage impeller chamber (112).

The discharge pipe (1) for discharging the refrigerant pressurized by the high-stage impeller (15), that is, the refrigerant subjected to the second-stage compression.
37) is connected to the casing body (3) so as to communicate with the scroll space (17) on the high-stage side.

As shown in FIG. 2A, the motor chamber (11) side of the first stationary journal bearing (31) and the motor chamber (11) side of the second stationary journal bearing (33) have: Donut-shaped annular members (51) each having a thick circular plate (50) sandwiched between two thin circular plates (52) are arranged. An insertion hole (51a) for inserting the rotating shaft (13) is formed at the center of the annular member (51), and an annular passage (51b) is formed on the outer periphery thereof. The rotation shaft (13) is inserted into the insertion hole (51) of the annular member (51).
It is arranged with a predetermined gap between the inner peripheral surface and the inner peripheral surface so as not to contact the inner peripheral surface of a). In the center circular plate (50) of the annular member (51), four spray passages (50a) penetrating in the radial direction are formed radially, and the insertion hole (51a) and the annular passage (51b) are formed. Communication is provided by each spray passage (50a). This spray passage (50a) is connected to the suction passage (14
1) and (142) form a refrigerant passage for directly blowing the low-temperature refrigerant introduced into the annular passage (51b) to the rotating shaft (13) and then introducing the refrigerant to the motor chamber (11).

Here, the flow passage cross-sectional area of the blowing passage (50a) is made smaller than the flow passage cross-sectional area of the suction passages (141) and (142) so that the speed of the refrigerant blown to the rotating shaft (13) increases. Is also set small. However, the flow passage cross-sectional area of the blowing passage (50a) may be set so that the refrigerant is blown at a speed suitable for cooling the rotating shaft (13), and if the flow rate of the refrigerant is an appropriate value, the suction The passages (141) and (142) may be equal to or larger than the cross-sectional area of the passage. From the viewpoint of reducing the pressure loss of the refrigerant, it is preferable that the flow passage cross-sectional area of the blowing passage (50a) is large, so that the flow cross-sectional area of the blowing passage (50a) depends on the cooling effect of the rotating shaft (13) and the pressure loss. It is desirable to set from both viewpoints. Also, the flow passage cross-sectional area of the blowing passage (50a) may be set so as to gradually decrease toward the downstream side. Further, it may be formed in a nozzle shape.

An annular groove (53) for heat dissipation is formed on the outer peripheral surface of the rotating shaft (13) on which the refrigerant from the blowing passage (50a) is blown, as an enlarged surface for promoting cooling. That is, the annular groove (53) is a herringbone groove (35) of the rotating shaft (13),
(95) formed in the vicinity of the motor chamber (11), the rotating shaft (13)
The heat conduction cools the herringbone grooves (35) and (95) and the labyrinth seal portions (45) and (96) to suppress the thermal expansion of the rotating shaft (13). Note that a fin may be provided on the rotating shaft (13) as an enlarged surface for promoting cooling.

Next, the operation of the turbo compressor (100) will be described. The first and second suction pipes (131) from the suction pipe (130),
The low-pressure refrigerant diverted to (132) and sucked into each blowing passage
(50a), is sprayed on the rotating shaft (13),
Introduced in (11). This refrigerant cools the rotating shaft (13) and also the motor (27), and the first and second outlet pipes (133),
(134). The refrigerant in both outlet pipes (133) and (134) merges in the first supply pipe (135) and is supplied as a low-pressure refrigerant to the low-stage impeller chamber (111). This low-pressure refrigerant is an impeller
The first stage compression is performed by the rotation of (75), and is discharged to the second supply pipe (136) as a pressurized intermediate-pressure refrigerant. The intermediate-pressure refrigerant passes through the second supply pipe (136), is introduced into the high-stage impeller chamber (112), is compressed in the second stage by the rotation of the impeller (15), and is further raised in pressure to high pressure It becomes a refrigerant. Then, the high-pressure refrigerant is discharged through the discharge pipe (137).

As described above, since the rotating shaft (13) is cooled by the low-temperature and low-pressure refrigerant before the pressure increase, even if it is heated by bearing friction or leakage of the high-temperature refrigerant, its temperature rise is suppressed. Therefore, the thermal expansion of the rotating shaft (13) is suppressed, and the clearance change in the dynamic pressure type journal gas bearings (37), (97) and the labyrinth seal portions (45, 96) is extremely small. Therefore, it is not necessary to set the clearances (C1) and (C2) to be relatively large in consideration of the thermal expansion of the rotating shaft (13) in advance, and to prevent seizure due to the thermal expansion of the rotating shaft (13). Can be. Therefore, it is possible to realize a highly efficient and highly reliable turbo compressor.

Further, the motor (27) in the motor chamber (11) is also cooled by the low-temperature low-pressure refrigerant before the pressure increase.
Is prevented from overheating. Therefore, heating of the rotating shaft (13) due to heat generated by the motor (27) is also suppressed. Further, the efficiency of the motor (27) itself is improved.

In particular, since the first and second suction passages (141) and (142) for dividing and guiding the suction refrigerant are provided to cool both sides of the rotary shaft (13), one of the two sides is cooled. The clearance on both sides of the rotating shaft (13)
(C1) and (C2) can be uniformly maintained at appropriate values. That is, since a plurality of suction passages (141) and (142) are provided so as to correspond to each of the gas bearings (37) and (97), each of the gas bearings (37) and (97) has a low-temperature refrigerant. Thus, the cooling can be directly performed, and the rotating shaft (13) can be effectively cooled.

Since the low-temperature refrigerant is intensively blown through each blowing passage (50a) by using the annular member (51),
It is possible to efficiently cool only the rotating shaft (13) without cooling the first and second stationary journal bearings (31) and (33). Therefore, it is possible to suppress the thermal expansion of the rotating shaft (13) while allowing the thermal expansion of these bearings (31), (33). Further, the outlet of the spray passage (50a) is provided with a dynamic pressure type journal gas bearing (37),
(97) and the labyrinth seal portions (45) and (96) are arranged near the portions, so that these portions can be cooled intensively and efficiently.

The blowing passage (50a) in the rotating shaft (13)
An annular groove (53) for promoting heat transfer is formed in the vicinity of the outlet, so that the cooling effect can be further enhanced.

It should be noted that the annular member (51) is not limited to the above-described embodiment, but may be one in which two blowing passages (50a) are arranged at opposing positions as shown in FIG.
As shown in (c), six spray passages (50a) may be arranged radially. Furthermore, as shown in FIG.
The four blowing passages (50a) may be arranged so as to be substantially tangential to the rotating shaft (13), whereby the refrigerant flows smoothly and the low-temperature refrigerant is transmitted to the rotating shaft (13). Heat can be further promoted and the cooling effect can be further enhanced.

As shown in FIG. 3, each spray passage (50
The outlet of (a) is inclined, and the spray direction of the refrigerant is changed to the rotation axis (1).
If the coolant is blown from an oblique direction at an acute angle to the axis of 3), the flow of the coolant becomes smooth and heat transfer is promoted. Therefore, the cooling effect of the rotating shaft (13) can be further enhanced. In particular, by inclining the outlet of each blowing passage (50a) to the motor (27) side, the first and second
Without cooling the stationary journal bearings (31), (33)
Further, it is possible to effectively cool only the rotating shaft (13) without causing unnecessary disturbance in the clearance of the gas bearing.

Further, as shown in FIG. 4, the heat dissipation groove (53) formed on the outer peripheral surface of the rotating shaft (13) is formed in a helical shape, so that the refrigerant is circulated by the helical groove (53). Rotary axis (1
3) It can be guided around smoothly, and its cooling effect can be further improved. In particular, by forming the spiral shape so as to guide the refrigerant to the motor (27) side, the first
It is possible to effectively cool only the rotating shaft (13) without cooling the second stationary journal bearings (31) and (33) and without causing unnecessary disturbance in the clearance of the gas bearing. It becomes possible.

As shown in FIG. 5, the blowing passage (50a)
Instead of using an annular member (51) having a
a) It may be formed by a conduit. For example, the first and second
The distal ends of the suction pipes (131) and (132) may be extended to near the rotating shaft (13), and the suction refrigerant may be blown from the suction pipes (131) and (132).

In this embodiment, the first and second outlet pipes (13) serve as passages for leading the refrigerant in the motor chamber (11).
Although 3) and (134) are provided, the passage for taking out the refrigerant in the motor chamber (11) may be constituted by a single passage. That is, the motor chamber (11) may be configured to communicate with the low-stage impeller chamber (111) only by the first supply pipe (135).

<Second Embodiment> As shown in FIG. 6, a turbo compressor (100b) according to the present embodiment has two compression units (201, 202) on the high-stage side and the low-stage side, as in the first embodiment. It has. In each compression section (201, 202), an impeller (15, 75) attached to the rotating shaft (13) is housed in the impeller chamber (111, 112), and a diffuser space (9,69) is provided around the outer periphery of the impeller (15, 75). ) And a scroll space (17, 77) are provided. Also in the present embodiment, two herringbone grooves (35, 95) are formed in the rotating shaft (13) so as to correspond to the compression sections (201, 202) on the high-stage side and the low-stage side. And, the rotating shaft (13) includes a low-stage compression unit (201) and a high-stage compression unit (202).
Are supported by the dynamic pressure gas bearings (37, 97) at a plurality of locations corresponding to.

Also in the present embodiment, each of the blowing passages (203, 204) on the low-stage side and the high-stage side is provided in the vicinity of each of the gas bearings (37, 97) on the rotating shaft (13) (hereinafter, the blowing portions (37a, 97a)). However, unlike Embodiment 1, the spray passage according to the present embodiment
(203,204) separates the suction gas and then sprays each part (37a,
97a), all of the suction gas is blown once to the high-stage blowing section (37a), and the suction gas blown to the high-stage blowing section (37a) is collected, and the low-stage blowing is performed. It is configured to spray the part (97a).

As shown in FIG. 7B, the blowing passages (203, 204) of the present embodiment are formed by a substantially annular annular member (205) having a concave central portion. As shown in FIG. 7A, on the outer peripheral side of the annular member (205), two outer peripheral grooves (206, 207) extending at an angle of 90 degrees along the outer periphery are formed. The outer peripheral groove (206) and the outer peripheral groove (207) are provided at point-symmetric positions with respect to the center point of the annular member (205). In addition, the outer peripheral groove (206) and the center hole (2
08) is a blowing passage (209) extending in the radial direction of the annular member (205).
a, 209b). On the other hand, the outer peripheral groove (207) and the center hole (208) communicate with each other via suction passages (210a, 210b) extending in the radial direction of the annular member (205).

As shown in FIG. 6, the annular member (205) is disposed inside the peripheral wall member (29). Then, the outer periphery of the annular member (205) provided on the high step side is covered by the peripheral wall member (29), so that the outer peripheral groove is formed as shown in FIG.
The (206) and the peripheral wall member (29) define a distribution passage (211) for distributing the suction gas from the first suction pipe (231) to the blow-out passages (209a, 209b). In addition, the outer peripheral groove (20
7) and the peripheral wall member (29), each suction passage (210a, 210b)
A converging passage (212) is formed in which the gas from the air is merged and supplied to the second suction pipe (232). It should be noted that the high-stage blowing passage (20) for blowing the intake gas to the high-stage blowing section (37a)
4) is formed by the distribution passage (211) and the outlet passages (209a, 209b). The above-mentioned suction passages (210a, 210b) and the merging passage (212) allow the blowing section (37a) on the high-stage side of the rotating shaft (13)
A recovery passage (213) for recovering the gas blown to the surface is formed.

Similarly, the annular member (20
By covering the outer periphery of 5) with the peripheral wall member (29),
By the outer peripheral groove (206) of the annular member (205) and the peripheral wall member (29), the suction gas from the second suction pipe (232) is supplied to each outlet passage.
A distribution passage (211) for distribution to (209a, 209b) is defined. Each of the suction passages (210) is formed by the outer peripheral groove (207) and the peripheral wall member (29) arranged point-symmetrically with the outer peripheral groove (206).
A converging passage (212) for converging the gas from a, 210b) and supplying it to the first supply pipe (135) is defined. The low-stage blowing passage (203) for blowing the intake gas to the low-stage blowing section (97a) includes the distribution passage (211) and the blowing passage (209a, 20
9b). The suction passage (210a, 210b)
And a collecting passage (214) for collecting the gas blown to the spraying portion (97a) on the lower stage side of the rotating shaft (13) by the merging passage (212).
Are formed.

The blowing passages (209a, 209) of the respective blowing passages (203, 204)
b) blows the gas into the blowing portion (37a, 97b) of the rotating shaft (13) so that the blowing direction of the gas is at an acute angle with respect to the axis of the rotating shaft (13).
It is formed so as to be sprayed obliquely to a).

In the present embodiment, the gas sucked from the first suction pipe (231) first passes through the high-stage blowing passage (204), and the blowing portion near the high-stage gas bearing (37). (37a). Most of the gas blown to the spraying part (37a) passes through the recovery passage (213) and passes through the second suction pipe (232).
Flows into. The gas in the second suction pipe (232) passes through the blowing passage (203) on the lower stage side and is blown to the blowing portion (97a) near the gas bearing (97) on the lower stage side. The gas blown to the blowing section (97a) passes through the recovery passageway (214) and passes through the first supply pipe (13
5). The gas in the first supply pipe (135) is supplied to the impeller chamber (111) on the lower stage side, where the first stage compression is performed by the rotation of the impeller (75), and the second stage refrigerant is pressurized as the intermediate pressure refrigerant. It is led out to the supply pipe (136). This intermediate pressure refrigerant is
After passing through the supply pipe (136), it is introduced into the high-stage impeller chamber (112), and the second stage is compressed by the rotation of the impeller (15). Then, the high-pressure refrigerant is discharged through the discharge pipe (137).

As described above, also in the present embodiment, the rotating shaft (13) is cooled by the low-temperature and low-pressure refrigerant before the pressure increase, so that the temperature rise is suppressed. Therefore, thermal expansion of the rotating shaft (13) is suppressed, and a change in clearance in the gas bearings (37, 97) and the labyrinth seal portions (45, 96) is extremely small. Therefore, bearing seizure can be prevented, and a highly efficient and highly reliable turbo compressor can be realized.

In particular, in the present embodiment, the suction gas is blown once to the blowing section (37a) on the high-stage side and then to the blowing section (97a) on the low-stage side. (37a), the temperature of the refrigerant to be blown
(97a) can be made lower than the temperature of the refrigerant blown. Therefore, a lower-temperature refrigerant can be sprayed on the high-stage side where the degree of thermal expansion of the rotating shaft (13) is expected to be large. As described above, a lower-temperature refrigerant can be blown to a portion having a large degree of thermal expansion, and a higher-temperature refrigerant than the low-temperature refrigerant can be blown to a portion having a small degree of thermal expansion. Cooling according to the degree of expansion of the shaft (13) can be performed. Therefore, the thermal expansion of the entire rotating shaft (13) can be more effectively suppressed.

<Third Embodiment> As shown in FIG. 8, a turbo compressor (100c) according to a third embodiment includes a high-stage blow passage (2c).
The outlet of 04) is closer to the rotating shaft (13) than the outlet of the blowing passage (203) on the lower stage side.

The high-stage spray passage (204) and the recovery passage (213)
Is formed by the same annular member (205) as in the second embodiment. On the other hand, the spray passage (203) on the lower stage side and the recovery passage
(214) is formed by an annular member (205a) in which the center hole of the annular member (205) is slightly larger. That is, in the present embodiment, the outlet of the blowing passage (203) on the lower stage side and the rotating shaft
The gap between the blowing section (97a) of (13) and the blowing section (37a) of the rotating shaft (13) is larger than the gap between the blowing port (204) on the high-stage side and the blowing section (37a). Has become.

During operation of the turbo compressor (100c), the first and second suction pipes are connected from the suction pipe (130) as in the first embodiment.
The low-pressure refrigerant diverted to (131, 132) and sucked passes through each of the blowing passages (203, 204), and each of the blowing portions (37a, 97a) of the rotating shaft (13).
Sprayed on. The refrigerant blown to each of the spray sections (37a, 97a) passes through the respective recovery passages (213, 214) to the first and second refrigerants.
It is led to the outlet pipe (133, 134). These outlet pipes (133,
The refrigerant in 134) joins in the first supply pipe (135),
The low-pressure refrigerant is supplied to the low-stage impeller chamber (111). As in the first embodiment, the low-pressure refrigerant is pressurized in the low-stage compression section (201) to become an intermediate-pressure refrigerant, and is further pressurized in the high-stage compression section (202) to become a high-pressure refrigerant. It is discharged through a discharge pipe (137).

In the present embodiment, the spray passage (204) on the high-stage side
Is closer to the rotating shaft (13) than the outlet of the lower-stage blowing passage (203), so that the higher-stage blowing unit (37a) is the lower-stage blowing unit (97a). Easier to cool than. Therefore,
Also in the present embodiment, similarly to the second embodiment, the rotation shaft (1
The cooling according to the degree of thermal expansion of 3) can be performed, and the thermal expansion of the entire rotating shaft (13) can be more effectively suppressed.

<Fourth Embodiment> As shown in FIG. 9, a turbo compressor (100d) according to a fourth embodiment includes first and second suction pipes (131, 132) branched from a suction pipe (130). A flow rate changing mechanism is provided.

Specifically, the first suction pipe (131)
A valve (233) is provided, and a second valve (234) is provided in the second suction pipe (132). These first and second valves (233, 234) are valves whose opening degree can be freely adjusted, and by adjusting their opening degrees, the first and second suction pipes (1
31, 132) can be adjusted. Here, the first valve (233) is the second valve (234)
The suction refrigerant flowing through the suction pipe (130) flows more into the second suction pipe (132) than the first suction pipe (131). . As a result, the flow rate and flow rate of the suction refrigerant are changed to the second suction pipe (132).
Is larger than the first suction pipe (131), and more suction refrigerant is blown to the blowing section (37a) on the higher stage than the blowing section (97a) on the lower stage.

Therefore, also in this embodiment, the rotation axis (1
Since the cooling according to the degree of the thermal expansion of 3) can be performed, the thermal expansion of the entire rotating shaft (13) can be more effectively suppressed.

The flow rate change mechanism provided in the first and second suction pipes (131, 132) is not limited to the valves (233, 234), and the flow rate of the second suction pipe (132) is controlled by the first suction pipe (131, 132). ) So that each suction pipe (131, 13
Any type can be used as long as the flow rate can be adjusted in 2). For example, an orifice may be used. Also,
The flow rate changing mechanism may be a mechanism that makes the flow rate of each suction pipe (131, 132) a constant flow rate, or a mechanism that can appropriately change the flow rate manually or automatically.

Further, instead of providing a flow rate change mechanism in the first and second suction pipes (131, 132), the low-stage and high-stage blowing passages (204, 203) themselves are changed so that the high-stage side is lower than the low-stage side. May be formed so as to increase the flow rate. For example, the flow path cross-sectional area of the second suction pipe (132) may be larger than that of the first suction pipe (131).

[0074]

As described above, according to the present invention, the rotating shaft
Motor room (11) in which a motor (27) for rotating (13) is arranged
Into the motor chamber
Since (11) is in a low-temperature and low-pressure atmosphere, thermal expansion of the rotating shaft (13) can be suppressed, and the rotating shaft (13) and each bearing (31, 33)
, The clearance (C1, C2) can be kept at an appropriate value. Therefore, seizure can be prevented while bearing performance is maintained, and both performance and reliability can be improved.

The suction gas is supplied to each gas bearing forming portion of the rotary shaft (13).
By providing a plurality of blowing passages (50a) for blowing in the vicinity of (35, 95), both gas bearing forming portions (35, 95) can be cooled directly and efficiently, and the rotation shaft (13) Although the impellers (15, 75) and the gas bearing forming portions (35, 95) are provided on both sides, the thermal expansion of the rotating shaft (13) can be reliably prevented. Therefore, a multi-stage turbo compressor excellent in both performance and reliability can be realized.

The blowing passage (50a) is connected to the rotating shaft (13) through the suction gas.
Formed so as to be sprayed obliquely to the axial direction of the
Alternatively, by forming the suction gas so as to be blown in the tangential direction of the rotation shaft (13), the flow of the suction gas can be made smooth, and heat transfer between the suction gas and the rotation shaft (13) is promoted. can do.

The blowing passage (50a) is connected to the suction shaft (13)
The rotating shaft (13) can be efficiently cooled by spraying on the portion which is easily overheated.

By forming the heat radiation groove (53) in the rotating shaft (13), the cooling of the rotating shaft (13) can be further promoted.

A plurality of compression units (201, 202) having impellers (15, 75) attached to the rotation shaft (13) of the motor (27), and the rotation shaft (13) is connected to the compression units (201, 202). Multiple gas bearings provided to support at corresponding multiple locations (37,97)
And a plurality of blowing passages (203, 204) for blowing suction gas to portions (37a, 97a) of the rotary shaft (13) in the vicinity of the gas bearings (37, 97).
Seizure can be prevented while maintaining the bearing performance of (37, 97), and both performance and reliability can be improved.

The blowing passage (203, 204) is connected to the high-stage blowing passage.
By forming the outlet of (204) closer to the rotation axis (13) than the outlet of the blowing passage (203) on the lower stage side,
Cooling according to the degree of thermal expansion of each part of the rotating shaft (13) becomes possible, and seizure of the bearing can be effectively prevented.

By forming the spray passages (203, 204) such that the spray amount on the high-stage side is larger than that on the low-stage side,
Cooling according to the degree of thermal expansion of each part of the rotating shaft (13) becomes possible, and seizure of the bearing can be effectively prevented.

The blowing passages (203, 204) are cooled by the gas cooled in the vicinity (97a) of the rotary shaft (13) in the vicinity of the high-stage gas bearing (97), and in the vicinity (37a) of the low-stage gas bearing (37). By being formed so as to cool, it is possible to perform cooling according to the degree of thermal expansion of each part of the rotating shaft (13), and it is possible to effectively prevent seizing of the bearing.

[Brief description of the drawings]

FIG. 1 is a sectional view of a turbo compressor according to an embodiment of the present invention.

FIGS. 2A to 2D are views showing various aspects of a blowing passage of an annular member.

FIG. 3 is a partial cross-sectional view showing a modified example of an annular member installation portion of the turbo compressor.

FIG. 4 is a view showing a modified example of the shape of the groove for heat radiation of the rotating shaft.

FIG. 5 is a cross-sectional view of a turbo compressor showing a modification of a blowing passage.

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

7A is a front view of the annular member, and FIG. 7B is a cross-sectional view of the annular member taken along line II of FIG.

FIG. 8 is a sectional view of a turbo compressor according to a third embodiment.

FIG. 9 is a sectional view of a turbo compressor according to a fourth embodiment.

[Explanation of symbols]

 (1) Casing (11) Motor room (13) Rotary shaft (15) Impeller (27) Motor (35), (95) Herringbone groove (gas bearing forming part) (37), (97) Dynamic pressure type journal gas bearing (Gas bearing) (43) Dynamic pressure thrust gas bearing (45) Labyrinth seal (50a) Spray passage (111), (112) Impeller chamber (131), (132) Suction passage (C1), (C2) Clearance

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Higashi 1304 Kanaokacho, Sakai-shi, Osaka Daikin Industries Sakai Works Kanaoka Plant

Claims (10)

[Claims] 1. A turbo compressor for compressing and discharging an intake gas in multiple stages, comprising a motor chamber (11) and first and second impeller chambers (111, 112) on both sides of the motor chamber (11). A casing (1) forming a compartment, a motor (27) housed in the motor chamber (11), a rotating shaft (13) connected to the motor (27), and a rotating shaft (13) on both sides of the rotating shaft (13). Provided and the first and second
First and second impellers (15, 75) respectively housed in the impeller chambers (111, 112), and the rotating shaft corresponding to the first and second impellers (15, 75).
First and second gas bearing forming portions (3) formed on both sides of (13)
5,95) and the first and second gas bearing forming portions (35,
95) are provided with the respective gas bearing forming portions (35, 95) and predetermined clearances (C1, C2) so as to form gas bearings (37, 97), and the rotating shaft (13 ) In a non-contact state, and a suction passage (141) for guiding the suction gas to the motor chamber (11) so as to cool the motor chamber (11) with the suction gas before the pressure increase. ,14
2) and equipped with a turbo compressor. 2. The suction passage includes first and second rotation shafts (13).
A plurality of blowing passages (50a) for blowing the suction gas to the vicinity of each of the gas bearing forming portions (35, 95) of the rotating shaft (13) so as to cool the gas bearing forming portions (35, 95) are provided. The turbo compressor according to claim 1. 3. A turbo compressor for compressing and discharging an intake gas in multiple stages, comprising at least a motor chamber (11) and first and second impeller chambers (111, 112) on both sides of the motor chamber (11). A casing (1) forming a compartment, a motor (27) housed in the motor chamber (11), a rotating shaft (13) connected to the motor (27), and a rotating shaft (13) on both sides of the rotating shaft (13). Provided and the first and second
First and second impellers (15, 75) respectively housed in the impeller chambers (111, 112), and the rotating shaft corresponding to the first and second impellers (15, 75).
First and second gas bearing forming portions (3) formed on both sides of (13)
5,95) and the first and second gas bearing forming portions (35,
95) are provided with the respective gas bearing forming portions (35, 95) and predetermined clearances (C1, C2) so as to form gas bearings (37, 97), and the rotating shaft (13 ) In a non-contact state, and the first and second shafts (13) of the rotary shaft (13) with the suction gas before pressurization.
A plurality of blowing passages (50a) for blowing the suction gas to the vicinity of each of the gas bearing forming portions (35, 95) of the rotating shaft (13) so as to cool the gas bearing forming portions (35, 95). Turbo compressor provided. 4. The spray passage (50a) is provided with a rotary shaft (1)
The turbo compressor according to any one of claims 2 and 3, wherein the turbo compressor is formed so as to blow in an oblique direction with respect to the axial direction of (3). 5. The spray passage (50a) is provided with a rotary shaft (1)
The turbo compressor according to any one of claims 2 to 4, wherein the turbo compressor is formed so as to blow in a tangential direction of (3). 6. The turbo compressor according to claim 2, wherein a groove (53) for heat radiation is formed in the rotating shaft (13). 7. A turbo compressor for compressing and discharging intake gas in multiple stages, comprising an impeller (15a, 7a) mounted on a rotating shaft (13) of a motor (27).
5a) and a plurality of gas bearings provided to support the rotating shaft (13) at a plurality of locations corresponding to the respective compression portions (201, 202) (37, 202).
97), and a plurality of blowing passages for blowing a suction gas to portions (37a, 97a) near the gas bearings (37, 97) on the rotating shaft (13).
(203,204). 8. An air outlet of each of the blowing passages (203, 204) is arranged at a distance from the rotary shaft (13) so as to provide a clearance (C1, C2) between the outlet and the rotary shaft (13). The gap between the outlet of the blowing passage (204) on the side and the rotating shaft (13) is the gap between the outlet of the blowing passage (203) on the lower stage and the rotating shaft (13). The turbo compressor according to claim 7, which is smaller than the turbo compressor. 9. The spray passage (203, 204) according to claim 7, wherein the blow passage (204) on the higher stage has a larger spray amount than the blow passage (203) on the lower stage. The turbo compressor as described. 10. A blowing passage (203, 204) blows a suction gas to a portion (97a) near a high-stage gas bearing (97) of a rotating shaft (13), and then collects the gas to recover a low-stage gas. 8. The structure according to claim 7, wherein the bearing is configured to spray on a portion (37a) near the bearing (37).
10. The turbo compressor according to any one of claims 9 to 9.