JP2002322999A - Centrifugal compressor and refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize a centrifugal compressor by preventing contamination of a gaseous refrigerant with a lubricant in the rear of an impeller and thereby dispensing with an oil mist separation tank. SOLUTION: The centrifugal compressor is provided with a main shaft 28 rotatably supported in a casing 27 and the first step and second step impellers 29 and 33 provided integrally with the main shaft 28, and sucks and compresses the gaseous refrigerant by rotating the impellers together with the main shaft 28. In the compressor, a gas venting chamber 45 and an oil reservoir chamber 48 are formed by providing a labyrinth seal 47 between a bearing 39 rotatably supporting the main shaft 28 in the casing 27 and the second step impeller 33. The gaseous refrigerant extracted from the gas venting chamber 45 is introduced into the suction side of the compressor, and the lubricant is returned from the oil reservoir chamber 48 to an oil tank 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal compressor for compressing a fluid by a rotating impeller, and a refrigerator having the same.

[0002]

2. Description of the Related Art An example of a centrifugal compressor is shown in FIG. In the drawing, reference numeral 1 denotes a casing, 2 denotes a main shaft, 3 denotes a first-stage impeller (impeller), 4 denotes a first-stage diffuser portion, 5 denotes a return bend, 6 denotes a guide vane, 7 denotes a second-stage impeller, 8
Denotes a second-stage diffuser portion, and 9 denotes a suction port. A bearing 10 is provided behind the second-stage impeller 7 to rotatably support the main shaft 2.

[0003] In this centrifugal compressor, after the fluid is sucked through the suction port 9, the fluid passes through the impeller 3, the diffuser 4, the return bend 5, and the guide vane 6 in order, and is pressurized, and is led to the entrance of the next stage. .

In the above-described centrifugal compressor, a seal member 11 such as a labyrinth seal is provided between the second-stage impeller 7 at the highest pressure and the bearing 10 to prevent gas refrigerant from leaking. However, this also does not completely prevent leakage. Therefore, a gas vent chamber 12 is provided behind the seal member 11, and the gas refrigerant flowing into the gas vent chamber 12 is extracted and returned to the suction side of the centrifugal compressor.

[0005]

In the above-mentioned centrifugal compressor,
After lubrication, the lubricating oil supplied to the bearing 10 temporarily flows out into the degassing chamber 12 and flows into the oil tank 14 provided in the casing 1 through the oil passage 13. Therefore, the lubricating oil in the form of a mist (mist) tends to float in the gas venting chamber 12, and the oil mist may be extracted together with the gas refrigerant.

When oil is bled to the suction side of the centrifugal compressor together with the gas refrigerant as described above, the oil tank 14
There is a problem that the amount of oil in the inside gradually decreases and causes insufficient lubrication due to insufficient oil. Further, the gas refrigerant leaking into the degassing chamber 12 has a high pressure and is easily dissolved in the oil. When the refrigerant is dissolved in the oil, the viscosity of the oil decreases, which is also one of the causes of poor lubrication. Therefore, conventionally, an oil mist separation tank is provided in an extraction pipe connecting the degassing chamber 12 and the vane chamber of the centrifugal compressor to separate the oil mist and return the oil mist to the oil tank 14. As it becomes larger,
There was a problem that the cost was increased by an amount equivalent to the oil mist separation tank.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and prevents mixing of a gas refrigerant and a lubricating oil at the rear of an impeller so that only the gas refrigerant can be bled so that an oil mist separation tank is formed. It is an object of the present invention to reduce the size and cost of a centrifugal compressor by discarding it, and to further reduce the size and cost of a refrigerator equipped with the centrifugal compressor.

[0008]

As means for solving the above-mentioned problems, a centrifugal compressor and a refrigerator having the following structures are employed. That is, a centrifugal compressor according to claim 1 of the present invention includes a casing, a rotating shaft rotatably supported by the casing, and an impeller provided integrally with the rotating shaft. A centrifugal compressor that sucks and compresses fluid by rotating the impeller together with a shaft, wherein the impeller is disposed between a bearing that rotatably supports the rotating shaft between the casing and the impeller. A first space in which the fluid flows in from the vehicle side and a second space in which lubricating oil flows in from the bearing side are provided, and the fluid is extracted from the first space, and the second space is extracted from the second space. The method is characterized in that the lubricating oil is extracted.

According to a second aspect of the present invention, there is provided the centrifugal compressor according to the first aspect, wherein the first space and the second space are provided between the casing and the rotary shaft. It is characterized by being partitioned by members.

According to a third aspect of the present invention, there is provided a centrifugal compressor according to the second aspect, wherein a labyrinth seal is used for the seal member.

According to a fourth aspect of the present invention, there is provided a centrifugal compressor.
4. The centrifugal compressor according to 2 or 3, wherein the fluid extracted from the first space is supplied to a suction side of the impeller.

In the centrifugal compressor according to the present invention, the space into which the fluid leaking from the impeller side and the space into which the lubricating oil flows from the bearing side are divided so as to mix the fluid and the lubricating oil. Is less likely to occur. Therefore, when returning the fluid leaking from the impeller side to the upstream side of the impeller, it is not necessary to provide an oil mist separator as in the related art. Also,
Since the gas refrigerant does not mix with the lubricating oil and the clay of the lubricating oil is kept at an appropriate level, the operation of the lubricating oil can be prevented from lowering and stable operation can be realized. Further, the oil rising phenomenon in which the lubricating oil is reduced by being mixed with the refrigerant is also prevented.

[0013] The refrigerator according to claim 5 is characterized in that:
A centrifugal compressor according to 3 or 4, a condenser for condensing and liquefying a gaseous refrigerant compressed by the centrifugal compressor,
A throttle valve for reducing the pressure of the refrigerant liquefied by the condenser;
An evaporator is provided that cools the object to be cooled by performing heat exchange between the refrigerant and the object to be cooled, the pressure of which is reduced by the throttle valve, and evaporates and vaporizes the refrigerant.

In the refrigerator according to the present invention, the downsizing of the centrifugal compressor and the stable operation thereof are realized as described above, so that the downsizing of the refrigerator itself and the stable operation can be realized.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a centrifugal compressor and a refrigerator according to the present invention will be described with reference to FIGS. 1 and 2 show the configuration of the refrigerator according to the present embodiment. The refrigerator shown in the figure includes an evaporator 16 that performs heat exchange between a refrigerant and cold water to cool the cold water and evaporates and vaporizes the refrigerant, and a compressor 17 that compresses the refrigerant vaporized in the evaporator 16. A condenser 18 that causes heat exchange between the refrigerant compressed in the compressor 17 and the cooling water to condense and liquefy the refrigerant, a throttle valve 19 that decompresses the refrigerant liquefied in the condenser 18, An intercooler 20 for temporarily storing and cooling the refrigerant liquefied in the condenser 18;
An oil cooler 21 that cools the lubricating oil of the compressor 17 using a part of the refrigerant cooled in the condenser 18;
7 for driving the motor 7.

The evaporator 16, the compressor 17, the condenser 18, the throttle valve 19, and the intercooler 20 are connected by a main pipe 23 to form a closed system for circulating the refrigerant.

The compressor 17 employs a two-stage turbo compressor, which is introduced into an impeller at the front stage to compress a gas refrigerant, and the refrigerant is introduced into an impeller at the subsequent stage to be further compressed and then condensed. To 18. The compressor 17 will be described later.

The condenser 18 comprises a main condenser 18a and an auxiliary condenser 18b called a subcooler.
a, the refrigerant is introduced in the order of the subcooler 18b, and a part of the refrigerant cooled in the main condenser 18a is
4, the lubricating oil is introduced into the oil cooler 21 without passing through the subcooler 18b to cool the lubricating oil. Apart from that, a part of the refrigerant cooled in the main condenser 18a is supplied to the branch pipe 25.
After passing through the casing of the motor 22 without passing through the sub-cooler 18b through the sub-cooler 18b, the stator and the coils (not shown) are cooled and then introduced into the evaporator 16.

The throttle valve 19 comprises a condenser 18 and an intercooler 20
, And between the intercooler 20 and the evaporator 16 to decompress the refrigerant liquefied in the condenser 18 stepwise.

The structure of the intercooler 20 is the same as that of a hollow container. The refrigerant cooled in the main condenser 18a and the subcooler 18b and temporarily reduced in the throttle valve 19 is temporarily stored therein to further cool it. The gas phase components in the intercooler 20 are introduced into the compressor 17 through the bypass pipe 26 without passing through the evaporator 16.

FIG. 3 shows the internal structure of the compressor 17. In the figure, reference numeral 27 denotes a casing, 28 denotes a main shaft (rotating shaft), 29 denotes a first-stage impeller (impeller), 30 denotes a first-stage diffuser portion, 31 denotes a return bend, 32 denotes a guide vane, and 33 denotes a second-stage impeller. , 34 are a second stage diffuser portion, 35 is a suction port, and 36 is a discharge port.

The first-stage diffuser section 30 is a vane diffuser having a plurality of vanes 30a arranged at equal intervals on the outer peripheral portion of the first-stage impeller 29, and the second-stage diffuser section 34 includes: , 2nd stage impeller 3
3 and a plurality of vanes 38a which are concentrically arranged and have no vanes and have vanes 38a arranged at equal intervals on the outer periphery of the parallel wall diffuser 37.
And a vane diffuser 38 having the same.

Behind the second stage impeller 33, the main shaft 28
The bearing 39 which rotatably supports is provided. A gear mechanism 40 for transmitting a driving force is provided between the motor 22 and the main shaft 28.

In the second-stage diffuser 34, one of the walls constituting the parallel-wall diffuser 37 can be moved toward and away from the other wall so that the effect of the parallel-wall diffuser 37 can be adjusted. Diffuser 38
A suitable diffuser effect can be obtained even when the suction flow rate of the fluid changes in combination with the above.

The compressor 17 includes a gear mechanism 40 and a motor 2.
An oil tank 41 for storing a lubricating oil for lubricating the oil tank 2 and an oil pump 43 for circulating the lubricating oil stored in the oil tank 41 through an oil pipe 42 are provided.

The oil sent from the oil tank 41 by the oil pump 43 is introduced into the oil cooler 20 and cooled by the refrigerant, and then returns to the compressor 17 and partially supports the gear mechanism 40 and the main shaft 28. It is supplied to a bearing (described later), and the rest is supplied to the motor 22.

The rotation of the first stage impeller 29 causes the suction port 3
The gas refrigerant sucked from 5 increases its speed and pressure by the action of the first-stage impeller 29, is slowed down in the process of passing through the first-stage diffuser unit 30, and converts kinetic energy into internal energy, Further, the pressure is increased by passing through the return bend 31 and the guide vane 32 in this order, and then guided to the entrance of the second-stage impeller 33. Second
The gas refrigerant sucked by the rotation of the stage impeller 33 is:
After passing through the second-stage impeller 33, the pressure is further increased through the same process. After passing through the second-stage diffuser section 34, the speed is again reduced to convert the kinetic energy into internal energy, and then the discharge is performed. It flows out of the outlet 36.

FIG. 4 shows the second-stage impeller 33 and its peripheral structure in more detail. As shown in the figure, a labyrinth seal 44 is provided behind the second-stage impeller 33 to prevent leakage of gas refrigerant compressed to a high pressure, and a gas venting chamber (first space) is provided behind the labyrinth seal 44. 45 are defined. The gas vent chamber 45 communicates with a vane chamber on the suction side of the compressor 17 through a gas return pipe 46 (see FIG. 2).

The bearing 39 is provided with a labyrinth seal (seal member) 47 for preventing lubricating oil from flowing into the gas venting chamber 45 by separating the end face facing the gas venting chamber 45 from the gas venting chamber 45. I have. This labyrinth seal 47
An oil sump chamber (second space) 48 is defined on the end face of the bearing 39 by the partition 50 and the partition 50.

Further, the casing 27 is formed with a communication hole 49 for communicating the oil sump chamber 48 with the oil tank 41, and the lubricating oil flowing into the oil sump chamber 48 is provided with the communication hole 4.
9, and flows into the oil tank 41.

In the compressor 17 configured as described above, the gas vent chamber 45 into which the gas refrigerant leaking from the second stage impeller 33 flows into the back, and the oil sump chamber 48 into which the lubricating oil leaking from the bearing 39 flows into But the labyrinth seal 47
Therefore, the oil mist does not mix into the gas refrigerant in the degassing chamber 45. Therefore, only the gas refrigerant can be bled and returned to the suction side of the compressor via the gas return pipe 46. Accordingly, it is not necessary to provide an oil mist separator in the gas return pipe 46 as in the related art, and the refrigerator equipped with the compressor 17 can be reduced in size and cost as compared with the related art.

Further, since the gas refrigerant does not mix with the lubricating oil in the oil sump chamber 48, the lubricating oil can be prevented from being diluted by the dissolution of the refrigerant, and the viscosity of the oil can be maintained at an appropriate level. In addition, since a so-called oil rising phenomenon in which lubricating oil is reduced by being mixed with the gas refrigerant can also be prevented, a factor of poor lubrication can be eliminated and stable operation can be realized.

In this embodiment, the degassing chamber 4
Although the labyrinth seal is used for the seal member that separates the oil reservoir 5 from the oil reservoir chamber 48, the present invention is not limited to this, and another seal member may be used. Further, the gas refrigerant extracted from the degassing chamber 45 may be introduced into the vane chamber in which the driving section of the second-stage diffuser section 34 is accommodated. The gas refrigerant introduced here is compressed by the second stage impeller 33.

[0034]

As described above, according to the compressor of the present invention, the space into which the fluid leaking from the impeller side and the space into which the lubricating oil flows from the bearing side are divided and partitioned. As a result, mixing of the fluid and the lubricating oil hardly occurs. Therefore, when returning the fluid leaking from the impeller side to the upstream side of the impeller, it is not necessary to provide an oil mist separator, so that the compressor can be downsized compared to the conventional one, and the cost can be reduced accordingly. Can be achieved.

Further, since the gas refrigerant does not mix with the lubricating oil and the clay of the lubricating oil is kept at an appropriate level, a decrease in lubricating action can be prevented and a stable operation of the centrifugal compressor can be realized. Furthermore, since the oil rising phenomenon in which the lubricating oil is reduced by being mixed with the refrigerant can be prevented, poor lubrication caused by insufficient oil can be eliminated.

According to the refrigerator of the present invention, by providing the centrifugal compressor capable of exhibiting excellent performance as described above, it is possible to reduce the size of the refrigerator itself and realize stable operation. .

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment according to the present invention, and is a perspective view of a refrigerator using a centrifugal compressor.

FIG. 2 is a schematic diagram showing a system configuration of the refrigerator shown in FIG.

FIG. 3 is a sectional view showing the internal structure of the centrifugal compressor.

FIG. 4 is a sectional view showing the internal structure of the centrifugal compressor in more detail.

FIG. 5 is a sectional view showing an example of the internal structure of a conventional centrifugal compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 16 Evaporator 17 Compressor 18 Condenser 19 Throttle valve 20 Intercooler 21 Oil cooler 22 Motor 28 Main shaft (rotating shaft) 29 1st stage impeller (impeller) 33 2nd stage impeller (impeller) 39 Bearing 41 Oil Tank 45 Gas release chamber (first space) 47 Labyrinth seal (seal member) 48 Oil reservoir chamber (second space)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Ueda 3-1-1 Asahicho, Nishibiwajima-cho, Nishi-Kasugai-gun, Aichi Prefecture F-term in the Cooling Business Division of Mitsubishi Heavy Industries, Ltd. (Reference) 3H034 AA02 AA18 BB03 BB06 BB17 CC03 DD01 EE04

Claims (5)

[Claims] A casing, a rotating shaft rotatably supported by the casing, and an impeller provided integrally with the rotating shaft. Fluid is generated by rotating the impeller together with the rotating shaft. A centrifugal compressor that sucks and compresses the fluid, wherein the fluid flows in from the impeller side between a bearing that rotatably supports the rotating shaft between the casing and the impeller. A space and a second space into which lubricating oil flows from the bearing side are provided, and the fluid is extracted from the first space and the lubricating oil is extracted from the second space. Centrifugal compressor. 2. The method according to claim 1, wherein the first space and the second space are
The centrifugal compressor according to claim 1, wherein the compressor is partitioned by a seal member provided between the casing and the rotation shaft. 3. The centrifugal compressor according to claim 2, wherein a labyrinth seal is used for said seal member. 4. The centrifugal compressor according to claim 1, wherein the fluid extracted from the first space is supplied to a suction side of the impeller. 5. The centrifugal compressor according to claim 1, 2, 3, or 4, wherein a gaseous refrigerant compressed by the centrifugal compressor is condensed,
A condenser to be liquefied; a throttle valve for reducing the pressure of the refrigerant liquefied by the condenser; and a heat exchange between the refrigerant and the object to be cooled by the throttle valve to cool the object to be cooled. And a evaporator for evaporating and vaporizing the refrigerant.