KR100343726B1 - Structure for reducing gas reakage of turbo compressor - Google Patents

Abstract

The present invention relates to a gas leakage reduction structure of a turbocompressor, and the present invention is provided with a plurality of impellers which are centrifugally compressed to refrigerant gas sequentially at both ends of a drive shaft which is coupled to a mover of a drive motor and rotates. In the turbocompressor, a radial bearing is mounted to radially support the drive shaft, and at least one end of the drive shaft is equipped with a thrust bearing for supporting the drive shaft in the axial direction. The thrust bearing has a disc shape. And a bearing member formed on both sides of the bearing member to be coupled to one end of the drive shaft, and fixedly disposed so as to face the bearing member, and a labyrinth seal formed on the surface opposite to both sides of the bearing member. The drive shaft is constituted by a plurality of support members Axis direction be the narrowing of the pores of the grabber rinsing chamber and a thrust bearing surface when the vibration is reduced backflow of the refrigerant gas, the vibration / noise of the compressor by reducing the critical speed shortens the axial length of the drive shaft is reduced stability is improved.

Description

STRUCTURE FOR REDUCING GAS REAKAGE OF TURBO COMPRESSOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas leakage reduction structure of a turbo compressor, and more particularly, to a gas leakage reduction structure of a turbo compressor when applying a bearing which is directly contacted and supported by a drive shaft such as a foil bearing.

Generally, a compressor converts mechanical energy into compressive energy of a compressive fluid, which is divided into reciprocating, scrolling, and centrifugal (commonly referred to as turbo) and vane (commonly referred to as rotary). .

Among them, a turbo compressor is generally known as a two-stage compression type turbo compressor, in which a fluid is sucked in an axial direction using a rotating force of an impeller like a vortex pump and compressed while being discharged in a centrifugal direction. Such turbo compressors are mainly used in large-capacity turbo compressors, such as centrally controlled air conditioners in buildings, but recently, small turbo compressors that are applicable to general home air conditioners have been developed.

The turbo compressor is divided into one stage, two stages, etc. according to the number of impellers (compression chamber), and may be classified into a back to back type or a face to face type according to the arrangement of the impeller. The back-to-back type may be arranged such that the back surfaces of the impeller face each other, whereas the face-to-face type is arranged so that the suction ends of the impeller face each other.

1 is a longitudinal sectional view showing a conventional two-stage compact turbo compressor of the face-to-face type.

As shown in the drawing, the conventional two-stage compact turbo compressor has a motor casing 1 having a predetermined internal volume, a first bearing plate 2A and a second covered on both sides of the motor casing 1. A bearing plate 2B, a shroud plate 3 mounted on an outer surface of the first bearing plate 2A, a first diffuser casing 4A mounted on an outer surface of the shroud plate 3, and A bearing cover 5 mounted on an outer surface of the second bearing plate 2B, and a volute casing 6 which receives the bearing cover 5 and is attached to the outer periphery of the second bearing plate 2B. And a second diffuser casing 4B mounted on the outer surface of the volute casing 6, a drive motor M mounted inside the motor casing 1, and a movement of the drive motor M. FIG. The first bearing plate 2A and the second bearing plate 2B pressed into the ruler MR and both ends thereof are The first impeller 8A fixed to the drive shaft 7 through which it communicates, and the 1st compression chamber Sc1 which consists of said shroud plate 3 and the 1st diffuser casing 4A fixed to one end of the drive shaft 7 above. And a second impeller 8B fixed to the other end of the drive shaft 7 and disposed in the second compression chamber Sc2 including the volute casing 6 and the second diffuser casing 4B. A first radial bearing 9A and a second radial bearing 9B, which are mounted to the first bearing plate 2A and the second bearing plate 2B and made of foil bearings to support the radial direction of the drive shaft 7, It is comprised between the 2nd bearing plate 2B and the bearing cover 5, and comprises the thrust bearing 10 which consists of foil bearing so that the axial direction of the drive shaft 7 may be supported.

The bearing cover 5 is formed in an annular shape so that the drive shaft 7 penetrates, and an inner surface thereof is formed on both sides of a bearing member 7A coupled to the drive shaft 7 together with an outer surface of the second bearing plate 2B. At the same time, a through hole (not shown) through which the drive shaft 7 penetrates is formed at the center thereof, and the inner circumferential surface of the through hole prevents leakage of refrigerant gas between the outer circumferential surfaces of the drive shaft 7. A labyrinth seal 5a is formed.

In the drawings, reference numeral 11 denotes a first gas passage, 12 denotes a second gas passage, SP denotes a suction tube, DP denotes a discharge tube, Sm denotes a motor chamber, MS denotes a stator, Ss1 denotes a first suction space, and Ss2 denotes a second suction. Space.

The conventional two-stage compact turbo compressor constructed as described above operates as follows.

That is, when power is applied to the drive motor M, the drive shaft 7 is supported by the radial bearings 9A, 9B and the thrust bearing 10 together with the movable element MR of the drive motor M. To rotate, and the first and second impellers 8A and 8B fixed to both ends of the driving shaft 7 rotate. At this time, the refrigerant gas sucked into the motor casing 1 through the suction pipe SP is sucked into the first compression chamber Sc1 through the first gas passage 11 and the first suction space Ss1, and thus the first impeller. The first stage compressed by the single stage 8A, the compressed shaft gas is sucked into the second compression chamber Sc2 through the plurality of second gas passages 12 and the second suction space (Ss2) and the second impeller It is compressed in two stages by 8B, and the compressed gas compressed in the two stages is collected by the volute casing 6 and discharged through the discharge pipe DP.

Here, the drive shaft (7) is rotated and the vibration occurs in the radial direction, as well as the first and second impellers 8A, 8B mounted at both ends are subjected to different pressures, and vibration occurs in the axial direction as well. In this radial and axial vibration, both radial bearings 9A and 9B and the foil of thrust bearing 10 are elastically slidably contacted with the outer circumferential surface of the drive shaft 7 and both side surfaces of the bearing member 7A. Supported.

At this time, a part of the pressurized shaft gas that is collected in the second suction space Ss2 is not sucked into the second compression chamber Sc2 by the pressure difference between the motor casing 1 and the second compression chamber Sc2, and the bearing cover. Although the through hole (not shown) of (5) and the outer peripheral surface of the drive shaft (7) flows back into the motor chamber (Sm) of the motor casing (1), the refrigerant gas to be flowed back through the bearing cover (5) It was interrupted by the labyrinth seal 5a provided in the hole.

However, in the conventional turbocompressor as described above, since the labyrinth seal 5a is formed in the radial direction of the drive shaft 7, the labyrinth seal 5a is applied to any one of the labyrinth seals 5a during the radial vibration of the drive shaft 7. Since the diameter of the drive shaft 7 and the inner diameter of the labyrinth seal 5a are unchanged even when they are close, the air gap c1 + c1 is further enlarged on the other side, and the reverse flow of the refrigerant gas increases. As the labyrinth seal 5a is formed on the inner circumferential surface of the in-bearing cover 5, the length of the drive shaft 7 is increased accordingly, and the vibration / noise of the compressor is increased and stability is lowered in consideration of the dangerous speed of the drive shaft 7. there was.

The present invention is made in view of the problems of the conventional turbo compressor as described above, before the refrigerant gas flowing into the second suction space is sucked into the second compression chamber to form a relatively low pressure portion through the axial direction of the drive shaft The purpose of the present invention is to provide a gas leakage reduction structure of a turbo compressor that can prevent backflow, and to reduce the risk speed by reducing the length of the drive shaft, thereby reducing the vibration / noise of the compressor and increasing stability. It is an object of the present invention to provide a gas leakage reducing structure.

1 is a longitudinal sectional view showing an example of a conventional turbo compressor.

Figure 2 is a longitudinal sectional view showing part "A" of Figure 1;

Figure 3 is a longitudinal sectional view showing an example of the turbo compressor provided with the gas leakage reduction structure of the present invention.

Figure 4 is a longitudinal sectional view showing the "B" portion of FIG.

5 is a longitudinal sectional view showing a modification to the "B" part of FIG.

** Description of symbols for the main parts of the drawing **

7: drive shaft 7A: bearing member

9A, 9B: Radial Bearing 10: Thrust Bearing

100: second bearing plate 200: bearing cover

110,210: labyrinth thread

In order to achieve the object of the present invention, a plurality of impellers are sequentially mounted to both ends of the drive shaft coupled to the mover of the drive motor to centrifugally compress the refrigerant gas, and both ends of the drive shaft support the drive shaft radially. In the turbocompressor in which a radial bearing is mounted so that at least one end of the drive shaft is mounted with a thrust bearing for supporting the drive shaft in an axial direction, the thrust bearing is formed in a disc shape and bearing surfaces are formed on both sides thereof. A plurality of support members formed by forming a bearing member which is coupled to one end of the drive shaft, and fixedly disposed to face the bearing member, and a labyrinth seal formed on a surface of the bearing member opposite to both sides of the bearing member. The gas leakage preventing structure of the turbo compressor, characterized in that Is provided.

Hereinafter, the gas leakage prevention structure of the turbocompressor according to the present invention will be described in detail with reference to the accompanying drawings.

Figure 3 is a longitudinal sectional view showing an example of the turbo compressor provided with a gas leakage reducing structure of the present invention, Figure 4 is a longitudinal sectional view showing a "B" part of FIG.

As shown therein, in the turbo compressor equipped with the gas leakage preventing structure according to the present invention, the drive shaft 7 is press-fitted into the movable element MR of the drive motor M mounted inside the motor casing 1, At both ends of the drive shaft 7, first compression chamber Sc1 made up of shroud plate 3 and first diffuser casing 4A, and second compression made up of volute casing 6 and second diffuser casing 4B. Suction ends of the first impeller 8A and the second impeller 8B provided in the seal Sc2 are fixed to face each other, and the first and second bearings are fixed to both sides of the motor casing 1. Radial bearings 9A and 9B made of foil bearings are mounted on the inner circumferential surfaces of the plates 2A and 100 so as to radially support the drive shaft 7 as described above. On the opposite surface of the bearing cover 200 fixed to the outer surface side of the drive shaft 7 A thrust bearing 10, which is also made of a foil bearing, is mounted to support the ring member 7A in the axial direction. The second bearing plate 100 and the bearing cover 200 are respectively provided on both sides of the bearing member 7A. It is fixedly placed to form a support member.

A plurality of second gas passages 12 communicating the first compression chamber Sc1 and the second compression chamber Sc2 to the first bearing plate 2A, the motor casing 1, and the second bearing plate 100. Is radially formed, and a second suction space Ss2 is formed between the bearing cover 200 and the volute casing 6 to communicate the respective second gas passages 12 and the second compression chamber Sc2. The thrust bearing 10 is formed on an inner side surface of the bearing cover 200 forming a part of the second suction space Ss2 and an outer side surface of the second bearing plate 100 corresponding thereto. The labyrinth seals 110 and 210 are formed on the outer surface of the second bearing plate 100 facing the bearing 10 and the inner surface of the bearing cover 200, respectively.

The second compression chamber side end portion of the drive shaft 7 is coupled with a bearing member 7A forming a thrust bearing surface together with an outer surface of the second bearing plate 100 and an inner surface of the bearing cover 200, and the lever The rinse seals 110 and 210 are disposed on the bearing surface of the second bearing plate 100 and the bearing surface outer side of the bearing cover 210 so as to face each other on both sides of the bearing member 7A.

In the drawings, the same reference numerals are given to the same parts as in the prior art.

MS, which is not described in the drawings, is a stator.

The general operation of the turbo compressor provided with the bearing structure of the present invention as described above is the same as in the prior art.

That is, when power is applied to the drive motor M, the drive shaft 7 is supported by the radial bearings 9A, 9B and the thrust bearing 10 together with the movable element MR of the drive motor M. And the first and second impellers 8A and 8B fixed to both ends of the driving shaft 7 rotate, and the refrigerant gas passes through the motor casing 1 to the first compression chamber. Sucked into Sc1 and compressed into one stage by the first impeller 8A, and the compressed compressed gas of the first stage is again sucked into the second compression chamber Sc2 and compressed into the second stage by the second impeller 8B. Discharged.

At this time, the pressurized shaft gas collected into the second suction space Ss2 is mostly sucked into the second compression chamber Sc2 by the second impeller 8B and is compressed and discharged, while a part of the pressurized shaft gas is compressed into the motor casing 1. ) And the second compression chamber Sc2 flows back to the motor casing 1 which forms a relatively low pressure part, but the refrigerant gas to flow back flows through the through hole of the bearing cover 200 and the outer circumferential surface of the drive shaft 7. Backflow is prevented by labyrinth seals 110 and 210 formed between the thrust bearing surfaces through the gaps c2 therebetween.

In this case, as shown in FIG. 4, the first impeller 8A and the second impeller 8B mounted at both ends of the drive shaft 7 receive different pressures, and the drive shaft 7 vibrates in either direction. Even though the two sides of the bearing member 7A of the drive shaft 7 corresponds to the outer surface of the second bearing plate 100 and the inner surface of the bearing cover 200, respectively, the labyrinth seals 110 and 210 are formed. Due to this, one of the thrust bare surface voids is always narrowed, the reverse flow of the refrigerant gas is significantly blocked.

Meanwhile, as shown in FIG. 5, since the labyrinth seals 110 and 210 are formed only on the outer surface of the second bearing plate 100 and the inner surface of the bearing cover 200, the through holes of the bearing cover 200. It is possible to make the thickness of the bearing cover thinner than to form the labyrinth seal, so that the length L 'of the drive shaft can be shorter than the length L of the conventional drive shaft, thereby risking the drive shaft 7. Lowering the critical speed also reduces the vibration / noise of the compressor and increases stability.

The gas leakage reduction structure of the turbocompressor according to the present invention is equipped with a plurality of impellers which sequentially centrifugally compress refrigerant gas at both ends of a drive shaft which is coupled to the mover of the drive motor and rotates, and at one end of the drive shaft. And a labyrinth seal on each of the inner surfaces of both support portions forming the thrust bearing surface together with the bearing portion, thereby providing a labyrinth during the axial vibration of the drive shaft. The air gap between the seal and the thrust bearing surface is narrowed, so that the reverse flow of the refrigerant gas is reduced, the shaft length of the drive shaft is shortened, and the danger speed is lowered, thereby improving the stability of the compressor.

Claims (2)

A plurality of impellers are coupled to the mover of the drive motor to sequentially centrifugally compress refrigerant gas at both ends of the rotating drive shaft, and radial bearings are mounted at both ends of the drive shaft to radially support the driving shaft. In at least one end of the drive shaft, the turbo compressor is provided with a thrust bearing for supporting the drive shaft in the axial direction, The thrust bearing is formed in a disk shape and forms bearing surfaces on both sides thereof, and includes a bearing member coupled to one end of the drive shaft, and fixedly disposed so as to face the bearing member, and a labyrinth seal on a surface opposite to both sides of the bearing member. A gas leakage preventing structure of a turbo compressor, characterized by comprising a plurality of support members each formed by a labyrinth seal. delete