JP6921135B2 - Turbo compressor and refrigerator using it - Google Patents

Description

The present invention relates to a turbo compressor and a refrigerator using the same.

The turbo compressor has an electric motor, an impeller, and a rotating shaft that transmits the power of the electric motor to the impeller. Here, when the rotating shaft is divided into an electric motor rotating shaft and an impeller rotating shaft, which are two separate parts, a speed-increasing gear connecting these rotating shafts is provided, and each rotating shaft is rotated by a bearing. Generally, it has a freely supported configuration. In this case, the power of the electric motor is transmitted to the impeller rotating shaft via the speed increasing gear.

On the other hand, there is also a gearless turbo compressor having a structure that does not use such a speed-increasing gear. In the case of a gearless turbo compressor, the power of the motor is directly transmitted to the impeller via one rotating shaft. With such a structure, gear loss in the speed increasing gear can be eliminated, the compressor performance can be improved, the number of parts of the compressor can be reduced, and the structure of the compressor can be simplified. Since the gearless turbo compressor operates the motor in a higher rotation speed range than the conventional compressor with a speed-increasing gear, noise and vibration of the rotating shaft may become a problem.

According to Patent Document 1, in a compressor used in a refrigerating apparatus and driven by a motor, a shaft connecting an impeller of the compressor and a rotor of the motor can be rotated by a pair of bearings (rolling bearings). The supported configurations are described.

In a rotating machine that operates at high speed, a plain bearing that supports the rotating shaft by a lubricating oil film that is interposed between the rotating shaft and the bearing is often adopted. In a plain bearing, an oil film pressure is generated by drawing lubricating oil into a wedge-shaped gap between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the bearing by shaft rotation, thereby supporting the load of the rotating shaft. Further, as compared with rolling bearings similarly used in rotating machines, they have features such as a large load capacity, a long life, low operating noise, high impact resistance, and high vibration absorption.

When operating at high speed, plain bearings may have problems with vibration phenomena such as forced vibration and self-excited vibration. In particular, self-excited vibration is a phenomenon in which the rotating shaft swings due to the damping effect of the lubricating oil film of the slide bearing, and is called oil whip or wheel whirl. The oil whip occurs at a high rotation speed of twice or more the critical speed, and once vibration occurs, it diverges without being attenuated, which may cause damage to the bearing and the compressor. Therefore, it is desirable to design the machine to operate while avoiding the rotation speed range in which forced vibration and self-excited vibration occur.

However, in recent years, with the increase in size and speed of rotating machines, suppression of vibration phenomena occurring within the operating range has become a design issue.

To solve such problems, there are a method of increasing the rigidity of the rotating shaft to increase the natural frequency, a method of increasing the bearing support points of the rotating shaft, or a method of adopting a bearing having excellent stability. As for slide bearings, so-called dynamic pressure bearings such as multi-arc bearings, tilting pad bearings, and floating bush bearings are known to have excellent shaft stability.

Patent Document 2 includes a three-arc bearing for attaching a spindle and a drive shaft to a gearbox in a centrifugal compressor, and the three-arc bearing effectively improves the certainty and stability of high-speed operation of the rotating shaft. It is described that the noise is reduced by making the bearing.

Japanese Unexamined Patent Publication No. 2008-82622 Special Table 2016-599275

In the centrifugal compressor described in Patent Document 2, a gear is provided between the drive motor and the impeller. In this document, the arrangement of the drive motor bearings is not specified.

In a compressor having a configuration in which both electric motors are supported, the generation of electrolytic corrosion due to circulating current becomes a problem. In order to prevent this, it is necessary to insulate the bearings and attach an earth brush, which causes problems such as complicated compressor structure and cost increase.

On the other hand, in a compressor having a configuration in which the electric motor is cantilevered and supported, since electrolytic corrosion does not need to be considered, insulation treatment is unnecessary and desirable.

From the viewpoint of preventing oil leakage from oil pipes, it is desirable to reduce the number of oil pipes and joints. When the structure is such that the lubricating oil is supplied from the pump to the compressor with a single pipe and the system is branched inside the casing to supply oil to each bearing, the motor can be cantilevered rather than the structure that supports both sides of the motor. It is desirable to shorten the bearing spacing by supporting it because the oil supply path can be shortened and the structure can be simplified easily.

However, if the structure is such that the motor is cantilevered and supported, the exciting force of the motor rotor becomes large, and the number of rotations at which self-excited vibration of the rotating shaft is generated decreases. In particular, a turbo compressor in which a rotating shaft equipped with an impeller is directly driven by an electric motor has a higher rotation speed of the electric motor than a conventional turbo compressor having a speed-increasing gear, and shaft vibration occurs within the operating range. Therefore, it is necessary to take measures against vibration.

INDUSTRIAL APPLICABILITY In a turbo compressor having a structure directly connected to a motor and supporting an electric rotor with a sliding bearing, electrolytic corrosion due to an electric motor circulating current is prevented, an insulating structure is not required, a refueling path is simplified, and vibration of a rotating shaft is made. The purpose is to suppress the above and enable high-speed rotation.

The turbo compressor of the present invention is arranged between an electric motor having a stator and a rotor, an impeller, a rotating shaft that directly connects the rotor and the impeller, and the rotor and the impeller, and via lubricating oil. It comprises at least two bearings to support the rotating shaft and a casing to accommodate them, the rotating shaft is arranged substantially horizontally, the rotor is cantilevered by the rotating shaft, and the at least two bearings are. , At least one is a multi-arc sliding bearing.

According to the present invention, in a turbo compressor having a structure directly connected to a motor and supporting an electric motor rotor with a sliding bearing, electrolytic corrosion due to the electric motor circulating current is prevented, an insulating structure is not required, a refueling path is simplified, and a rotating shaft is used. It is possible to suppress the vibration of the motor and enable high-speed rotation.

It is a schematic cross-sectional view which shows the whole structure of the turbo compressor which concerns on one Embodiment of this invention. FIG. 1 is a cross-sectional view taken along the line AA of FIG. It is a figure which looked at the side of the multi-circular plain bearing 8 in the state where the bearing housing 3 of FIG. 1 was disassembled. It is a figure which shows the contact surface of the multi-circular plain bearing 8 of FIG. 1 with a bearing housing 3. FIG. 4 is a cross-sectional view taken along the line BB of FIG. It is schematic cross-sectional view which shows the whole structure of the turbo compressor which concerns on other embodiment of this invention. It is a perspective view seen from the side of a bearing housing 3 in a state where the multi-circular bearing 68 of FIG. 6 was disassembled. FIG. 7 is a vertical cross-sectional view of the multi-circular bearing 68 of FIG. 7. FIG. 5 is a cross-sectional view taken along the line AA of the perfect circular sliding bearing according to the third embodiment. It is a schematic block diagram which shows the refrigerator of this invention.

(Embodiment 1)
The present invention relates to a gearless turbo compressor which is a turbo compressor directly connected to a motor and a refrigerator using the gearless turbo compressor. Here, the rotating shaft of the gearless turbo compressor is arranged in a substantially horizontal direction inside the casing and is supported by a dynamic pressure plain bearing.

Here, the "substantially horizontal direction" includes a direction tilted by about 10 degrees with respect to the true horizontal direction orthogonal to the direction of gravity. This takes into consideration the installation environment when installing the turbo compressor. Of course, such an inclination with respect to the true horizontal direction is preferably small, preferably 5 degrees or less, and more preferably 3 degrees or less. In any case, by using the dynamic pressure plain bearing (multi-arc plain bearing) according to the present invention, the runout of the rotating shaft can be suppressed.

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

FIG. 1 is a schematic cross-sectional view showing the overall configuration of the turbo compressor of the present invention.

As shown in this figure, the turbo compressor 1 includes impellers 5 and 6, an electric motor 10, a rotating shaft 7 connecting them, and a multi-arc sliding bearing 8 and 9 supporting the rotating shaft 7 (hereinafter, “many”). Also called "arc bearing"). These components are housed inside the casing. The electric motor 10 has an electric motor stator 11 (stator) and an electric motor rotor 12 (rotor). The motor rotor 12 is directly connected to the impellers 5 and 6 via a rotating shaft 7 without gears. The impellers 5 and 6 are driven by the electric motor 10.

The casing includes an impeller casing 2 for accommodating the impellers 5 and 6, a bearing housing 3 for installing the multi-arc slide bearings 8 and 9, and a motor casing 4 for accommodating the motor 10. The impeller casing 2 and the motor casing 4 are connected in the horizontal direction and have a cylindrical shape as a whole. The motor stator 11 is fixed to the inner wall of the motor casing 4.

The rotating shaft 7 is arranged at the center of the impeller casing 2 and the motor casing 4, and is supported by the multi-arc sliding bearings 8 and 9. The multi-arc slide bearings 8 and 9 are fixed to the bearing housing 3.

As shown in this figure, the electric motor 10 is arranged at one end of the rotating shaft 7. The end of the rotating shaft 7 on the motor 10 side is not supported by bearings or the like. In other words, the motor rotor 12 is cantilevered by the multi-arc slide bearings 8 and 9. In other words, the turbo compressor 1 has an overhang structure in which the motor 10 (motor rotor 12) is supported by the multi-arc slide bearings 8 and 9.

The bearing housing 3 is provided with lubrication passages 13a, 13b, 13c (lubricating oil supply passages). An external oil supply pipe (not shown) of the turbo compressor 1 is connected to the oil supply passage 13a, and lubricating oil is supplied from the oil supply port 13. Lubricating oil is supplied to the multi-arc slide bearings 8 and 9 through the oil supply passages 13a, 13b and 13c. In other words, the lubricating oil supply path (lubricating passage 13a) is branched into lubrication passages 13b and 13c and communicates with two bearings (multi-arc slide bearings 8 and 9).
Since the turbo compressor 1 has an overhang structure as described above, a bearing can be arranged at the center of the rotating shaft 7. Therefore, the oil supply passages 13a, 13b, and 13c need only be formed in the bearing housing 3, and the compressor structure can be simplified.

In the turbo compressor of the present invention, as shown in this figure, the motor rotor 12 is cantilevered in the horizontal direction by the multi-arc sliding bearings 8 and 9, so that the turbo compressor has a mechanism of being supported by bearings at both ends. The natural frequency of the rotating shaft 7 may be smaller than that of a machine (rotating machine), and the number of rotations at which self-excited vibration or resonance occurs tends to be lower. Further, the sensitivity when an external force is applied to the motor rotor 12 during high-speed rotation is high, and the shaft vibration at the time of resonance becomes large.

Therefore, it is a problem to suppress self-excited vibration and resonance of the rotating shaft 7 inside the multi-arc slide bearing 9 shown in this figure.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1 and shows a detailed configuration of a multi-arc slide bearing.

The multi-arc slide bearing 8 shown in this figure is a tri-arc slide bearing (hereinafter, also referred to as a “tri-arc bearing”). A rotating shaft 7 is inserted in the center of the multi-arc slide bearing 8. The center of the rotating shaft 7 is arranged at the center of the multi-circular plain bearing 8 (bearing center). That is, the rotating shaft 7 and the multi-arc sliding bearing 8 are installed so that their centers are the same. The diameter of the rotating shaft 7 is φD.

The multi-arc slide bearing 8 has a concentric arc surface 14, an eccentric arc surface 15, and a refueling groove 16. The radius of the concentric arcuate surface 14 is R ₀ . The center of the eccentric arcuate surface 15 is different from the center of the concentric arcuate surface 14. The radius of the eccentric arcuate surface 15 is R ₁ . The radius of curvature of the refueling groove 16 is smaller than the radius of the concentric arcuate surface 14 and the eccentric arcuate surface 15.

The distance between the surface on which the eccentric arc surface 15 is extrapolated and the concentric arc surface 14 at the deepest portion of the refueling groove 16 is δ ₁ . The distance (gap) between the rotating shaft 7 and the concentric arcuate surface 14 is δ ₂ . δ _{2 is the difference between the radius R 0} of the concentric arcuate surface 14 and the radius (φD / 2) of the rotating shaft 7.

The opening angle (central angle) of the eccentric arcuate surface 15 from the portion where the eccentric arcuate surface 15 contacts the concentric arcuate surface 14 to the deepest portion of the refueling groove 16 is θ _{1 when the center of the rotation axis 7 is used as a reference.} .. The opening angle (central angle) of the concentric arcuate surface 14 is θ ₂ .

In this figure, the concentric arcuate surface 14, the eccentric arcuate surface 15, and the oil supply groove 16 are represented as arcs, but the cross-sectional shapes thereof are not limited to the arcs, and the pressure distribution of the lubricating oil is in a desired state. Any shape may be used.

The gap between the rotating shaft 7 and the multi-arc sliding bearing 8 is filled with lubricating oil supplied from the outside. The concentric arcuate surface 14 determines the minimum portion of the gap. The eccentric arcuate surface 15 is arranged eccentrically from the center of the bearing so that the gap gradually narrows toward the rotation direction of the rotating shaft 7 and is connected to the concentric arcuate surface 14. Three concentric arcuate surfaces 14 and three eccentric arcuate surfaces 15 are formed so that the concentric arcuate surfaces 14 and the eccentric arcuate surfaces 15 are arranged at an equal angle. In other words, the plurality of concentric arcuate surfaces 14 are formed so as to be arranged at an equal angle, and the plurality of eccentric arcuate surfaces 15 are formed so as to be arranged at an equal angle. A lubrication groove 16 for supplying lubricating oil is formed between the concentric arcuate surface 14 and the eccentric arcuate surface 15.

Here, "equal angle arrangement" means that they are arranged at equal angles in the circumferential direction. Therefore, it can be said that the concentric arcuate surfaces 14 are arranged on the inner wall surface of the multi-arc sliding bearing 8 at an angle equal to the rotation direction of the rotating shaft 7. Similar to the concentric arcuate surface 14, the eccentric arcuate surface 15 is also arranged on the inner wall surface of the multi-arc sliding bearing 8 at an angle equal to the rotation direction of the rotating shaft 7.

Similar to the multi-arc slide bearing 8, the multi-arc slide bearing 9 also has a concentric arc surface, an eccentric arc surface, and a refueling groove on its inner wall surface.

With the bearing configuration as shown in this figure, a non-uniform distribution of gaps is formed on the outer peripheral surface of the rotating shaft 7. As the rotation shaft 7 rotates, a pressure distribution is generated in the rotation direction of the rotation shaft 7 in the gap. This pressure distribution has three peaks (maximum values) in the rotation direction of the rotating shaft 7 in the case of a three-circle arc bearing as shown in this figure. Since the peaks are distributed at an equiangular angle, the rotating shaft 7 is supported from three directions via the lubricating oil, and the vibration of the rotating shaft 7 is suppressed. As a result, stable operation can be achieved even if the rotation speed of the turbo compressor is increased, and noise generation can be suppressed.

Although the three arc bearings are shown in this figure, the present invention is not limited to this, and the same effect can be obtained with a multi arc bearing having four or more arc shapes.

FIG. 3 is a view seen from the side of the multi-circular plain bearing 8 in a state where the bearing housing 3 of FIG. 1 is disassembled.

As shown in FIG. 3, a lubrication groove 34 for supplying lubricating oil is formed on the end surface 32 of the bearing housing 3. The refueling groove 34 is provided on the end surface 32 in an arc shape. Lubricating oil is supplied from a lubrication port 13 provided at the opposite end of the bearing housing 3, enters the lubrication groove 34 through the lubrication passages 13a and 13b, and is supplied to the multi-arc slide bearing 8 (FIG. 1). It is configured to. The refueling groove 34 has an arc shape, and the end opposite to the side of the refueling passage 13b serves as a dead end for the lubricating oil.

Further, the bearing housing 3 has a flange portion 31. The flange portion 31 is sandwiched and fixed between the impeller casing 2 and the motor casing 4 shown in FIG.

The bearing housing 3 has a through hole 33 penetrating the flange portion 31 and the end surface 32. A rotation shaft is inserted into the through hole 33.

FIG. 4 is a diagram showing a contact surface of the multi-circular plain bearing 8 of FIG. 1 with the bearing housing 3.

As shown in FIG. 4, the multi-arc slide bearing 8 is provided with three oil supply passages 42 at equal angles. Lubricating oil is supplied to these three oil supply passages 42 from the oil supply groove 34 of FIG. Further, the multi-arc slide bearing 8 has a through hole 41. A rotation shaft is inserted into the through hole 41.

FIG. 5 is a cross-sectional view taken along the line BB of FIG.

As shown in FIG. 5, the oil supply passage 42 is connected to the oil supply passage 43 inside the multi-arc slide bearing 8. From the viewpoint of the manufacturing process, it is desirable that the oil supply passage 43 is drilled from the outer peripheral surface of the multi-arc sliding bearing 8 toward the center. Therefore, after the oil supply passage 43 is formed, the oil supply passage 43 remaining on the outer peripheral portion of the multi-arc sliding bearing 8 is sealed by welding or the like, and the sealing portion 44 is formed.

With such a configuration, lubricating oil is supplied to the rotating shaft side of the multi-arc sliding bearing 8.

(Embodiment 2)
FIG. 6 is a schematic cross-sectional view showing the overall configuration of the turbo compressor according to another embodiment of the present invention.

The difference from FIG. 1 in this figure is that the bearing portion is composed of multi-circular plain bearings 68 and 69 having a small diameter portion. This small diameter portion is inserted inside the bearing housing 3. The bearing housing 3 has refueling passages 13d and 13e connected to the refueling passage 13b. The oil supply passage 13d of the bearing housing 3 is configured to supply lubricating oil to the small diameter portion of the multi-arc slide bearing 68, and the oil supply passage 13e of the bearing housing 3 is configured to supply lubricating oil to the small diameter portion of the multi-arc slide bearing 69.

FIG. 7 is a perspective view of the multi-arc slide bearing 68 of FIG. 6 as viewed from the side of the bearing housing 3 in a disassembled state.

In FIG. 7, the multi-arc slide bearing 68 includes a flange portion 68a and a small diameter portion 68b. Both the flange portion 68a and the small diameter portion 68b have a through hole 71. A rotation shaft is inserted into the through hole 71. A refueling groove 72 is provided on the outer peripheral portion of the small diameter portion 68b. The flange portion 68a is provided with a bolt hole 73.

FIG. 8 is a vertical cross-sectional view of the multi-arc slide bearing 68 of FIG.

As shown in FIG. 8, the oil supply groove 72 is connected to the oil supply passage 81 leading to the through hole 71. The lubricating oil supplied through the oil supply passage 13d of the bearing housing 3 shown in FIG. 6 is supplied to the through hole 71 via the oil supply groove 72 and the oil supply passage 81.

(Embodiment 3)
Embodiments 1 and 2 have two bearings, both of which are multi-arc plain bearings, but the present invention is not limited to this, and one of them may be a perfect circular plain bearing. FIG. 9 shows an example of a perfect circular slide bearing. This perfect circular slide bearing is provided on one of the two bearings indicated by reference numerals 8 and 9 in FIG. 1, and the other is a multi-arc slide bearing (for example, a tri-arc bearing).

By using a multi-arc slide bearing at least one of them, the effect of suppressing the runout of the rotating shaft can be obtained.

Further, the multi-arc slide bearing can correctly form the pressure distribution of the lubricating oil when the rotating shaft rotates in the normal direction. On the other hand, when the compressor is suddenly stopped, the rotating shaft may temporarily rotate in the reverse direction due to the backflow of the refrigerant gas, and the above-mentioned effect of the multi-arc slide bearing may not be sufficiently obtained. In such a case, there is a concern about seizure of the bearing on the motor side, which has a large load, and it is necessary to prevent it. In the present embodiment, the above concern can be suppressed by using one of them as a perfect circular slide bearing. More preferably, by using only the bearing on the motor side as a perfect circular slide bearing, seizure during reverse rotation can be effectively prevented. Since one of the bearings is a multi-arc slide bearing, the effect of suppressing the runout of the rotating shaft can also be obtained.

In FIG. 9, the perfect circular slide bearing has a concentric arcuate surface 114 and a refueling groove 116. The radius of the concentric arcuate surface 114 is R ₁₁ . The oil supply groove 116 corresponds to a gap between the outer surface of the rotating shaft 7 and the concentric arc surface 114. The distance (gap) between the rotating shaft 7 and the concentric arcuate surface 114 is δ ₁₁ . The radius (φD / 2) of the rotating shaft 7 is the same as that of the rotating shaft 7 of the first and second embodiments. The gap δ ₁₁ differs depending on the position of the concentric arcuate surface 114 because the rotating shaft 7 is displaced while rotating rather than immovably at a fixed position in the bearing.

In the third embodiment, it is preferable that the center of the concentric arc surface of the perfect circular slide bearing and the center of the concentric arc surface of the multi-arc slide bearing are on the same straight line.

In the third embodiment, the radius of the concentric arcuate surface 114 of the perfect circular slide bearing is larger than the radius of the concentric arcuate surface 14 of the multi-arc slide bearing or the radius of the eccentric arcuate surface. However, the present invention is not limited to this, and the radius of the concentric arcuate surface 114 of the perfect circular bearing may be configured to be the same as the radius of the concentric arcuate surface 14 of the multi-arc slide bearing or the radius of the eccentric arcuate surface.
In the third embodiment, the lubrication grooves and the lubrication passages for the perfect circular slide bearing may be the same as those in the first and second embodiments, may be different paths, and the number thereof may be increased or decreased.

(Separate embodiment)
(1) In at least one bearing, a perfect circular plain bearing and a multi-arc plain bearing may be arranged in series in the thickness direction (direction parallel to the axis of the rotating shaft). In this case, it is preferable that the thickness of the bearing in which the two types of bearings are arranged in series is thicker than the thickness of the bearing composed of only one type of bearing.
(2) In the first and second embodiments, it is preferable that the centers of the concentric arc planes of the two multi-arc slide bearings are on the same straight line.
(3) In the first to third embodiments, the two bearings are arranged substantially in the middle between the rotor and the impeller, but the present invention is not limited to this, and the rotor is proximal (distal to the impeller) or rotated. It may be located distal to the child (or proximal to the impeller).
(4) In the first to third embodiments, an example of two bearings has been given, but the number of bearings may be three or more. However, the smaller the number of bearings, the easier it is to make the refueling passage, refueling groove, etc. a simpler structure.

FIG. 10 is a schematic configuration diagram showing a refrigerator (freezing cycle) of the present invention.

The refrigerator 90 shown in FIG. 10 includes a turbo compressor 1, a condenser 92, a pressure reducing device 91 (expansion valve), an evaporator 93, and a refrigerant pipe 95 connecting them. The turbo compressor 1 compresses the low-temperature low-pressure refrigerant gas, discharges the high-temperature high-pressure refrigerant gas, and sends it to the condenser 92. The refrigerant gas sent to the condenser 92 exchanges heat with the cooling water flowing in the condenser 92, is cooled and condensed, and becomes a refrigerant liquid. Then, the refrigerant liquid passes through the decompression device 91, is depressurized, and is sent to the evaporator 93. The refrigerant liquid sent to the evaporator 93 exchanges heat with the cold water flowing in the evaporator 93, is heated and evaporates, becomes refrigerant vapor, and is sent to the turbo compressor 1. The cooling water that has taken heat from the refrigerant gas by the condenser 92 is sent to a cooling tower (not shown) or the like and dissipates heat to the atmosphere. The cold water cooled by heat exchange with the refrigerant liquid evaporated by the evaporator 93 is used for air conditioning of a building or the like.

1: Turbo compressor 2: Impeller casing 3: Bearing housing 4: Motor casing 5, 6: Impeller 7: Rotating shaft 8, 9: Multi-arc plain bearing 10: Electric motor 11: Motor stator 12: Motor rotor 13 : Refueling port 13a, 13b, 13c, 13d, 13e: Refueling passage 14, 114: Concentric arc surface 15: Eccentric arc surface 16: Refueling groove 31: Flange 32: End surface 33: Through hole 34: Refueling groove 41: Through hole 42, 43: Refueling passage 44: Sealing portion 68, 69: Multi-arc sliding bearing 68a: Flange portion 68b: Small diameter portion 71: Through hole 72: Refueling groove 73: Bolt hole 81: Refueling passage 90: Refrigerator 91: Decompression Device 92: Condenser 93: Evaporator 95: Flange piping

Claims (8)

A turbo compressor that has a structure directly connected to a motor and supports the rotor of an electric motor with plain bearings.
An electric motor with a stator and a rotor,
With an impeller
A rotating shaft that directly connects the rotor and the impeller,
At least two bearings arranged between the rotor and the impeller and supporting the rotating shaft via lubricating oil,
With a casing to accommodate these,
The axis of rotation is arranged in a substantially horizontal direction.
The rotor is cantilevered and supported by the rotating shaft.
The at least two bearings are turbo compressors, one of which is a multi-arc slide bearing. The turbo compressor according to claim 1, wherein the multi-arc slide bearing has a concentric arc surface, an eccentric arc surface, and a lubrication groove to which the lubricating oil is supplied. The multi-arc slide bearing has a plurality of concentric arc surfaces and an eccentric arc surface.
The plurality of concentric arc planes are formed so as to be arranged at an equal angle.
The turbo compressor according to claim 2, wherein the plurality of eccentric arc surfaces are formed so as to be arranged at an equal angle. The turbo compressor according to any one of claims 1 to 3, wherein the multi-circular plain bearing is a tri-circular plain bearing. The casing has one fuel filler port and the lubricating oil supply path.
The turbo compressor according to any one of claims 1 to 4, wherein the supply path is branched and communicates with the two bearings. The casing includes an impeller casing, a motor casing, and a bearing housing disposed between them.
The bearing housing has one fuel filler port and the lubricating oil supply path.
The turbo compressor according to any one of claims 1 to 4, wherein the supply path is branched and communicates with the two bearings. The turbo compressor according to any one of claims 1 to 6, wherein at least one of the at least two bearings is a perfect circular slide bearing. A refrigerator comprising the turbo compressor according to any one of claims 1 to 7, a condenser, a decompression device, an evaporator, and a refrigerant pipe connecting them.

Images