WO2022240096A1

WO2022240096A1 - Turbocompressor and method for controlling same

Info

Publication number: WO2022240096A1
Application number: PCT/KR2022/006567
Authority: WO
Inventors: 오준철; 배효조; 문창국; 이병철
Original assignee: 엘지전자 주식회사
Priority date: 2021-05-12
Filing date: 2022-05-09
Publication date: 2022-11-17
Also published as: EP4339464A1; KR20220153925A; KR102548667B1

Abstract

The present invention provides a turbocompressor and a method for controlling same, the turbocompressor comprising: a driving unit for enabling generation of rotational power for compressing refrigerant; a shaft extending in one direction and installed in the driving unit to be able to rotate by means of power generated by the driving unit; and first to third compression units installed on the shaft from one side of the shaft. The first compression unit comprises a first impeller rotated by power from the driving unit such that refrigerant discharged from an evaporator can be suctioned, and the suctioned refrigerant can be compressed and discharged. The second compression unit comprises a second impeller rotated by power from the driving unit such that refrigerant discharged from the first compression unit can be suctioned, and the suctioned refrigerant can be compressed and discharged. The third compression unit comprises a third impeller. The third impeller makes it possible to suction refrigerant discharged from the second compression unit, to compress the suctioned refrigerant, and to discharge same to the outside. Alternatively, the third impeller makes it possible to provide the refrigerant while bypassing the first compression unit.

Description

Turbo compressor and method for controlling it

The present invention relates to a turbo compressor and a method for controlling the same, and more particularly, to a turbo compressor having a structure that can be miniaturized while producing a high compression ratio by a three-stage structure impeller, and a method for controlling the same.

In general, compressors are applied to vapor compression type refrigerating cycles (hereinafter, abbreviated as refrigerating cycles) such as refrigerators or air conditioners. The compressor may be classified into a reciprocating type, a rotary type, a scroll type, and the like according to a method of compressing refrigerant.

A reciprocating compressor is a compressor in which a piston in a cylinder compresses gas by reciprocating motion. Among them, a scroll compressor engages a fixed scroll fixed in the inner space of an airtight container to perform a orbital motion, thereby performing a orbital movement with a fixed wrap of the fixed scroll and an orbiting scroll. It is a compressor in which a compression chamber is formed between the orbiting wraps of the

A turbo compressor is a type of centrifugal compressor, which compresses gas with centrifugal force by rotating the impeller wheels of the curved blades in the casing. Turbo compressors have advantages over reciprocating and screw-type compressors such as large capacity, low noise, and low maintenance. In addition, it is possible to produce clean compressed gas that does not contain oil.

A centrifugal turbocompressor consists of an impeller to compress the gas and a diffuser to decelerate the accelerated gas flow and convert it to pressure. When the motor rotates the impeller at high speed, external gas is sucked in along the axial direction of the impeller, and the sucked gas is discharged in the centrifugal direction of the impeller. The fluid discharged in the centrifugal direction of the impeller is compressed while moving along a flow path formed inside the turbo compressor.

Among the two-stage turbo compressors, the counter-type turbo compressor has first and second stage impellers centered on the motor and disposed opposite to each other on both sides of the motor. In this structure, both the impeller and the journal bearing that apply the load to the shaft are symmetrically arranged to take a mechanically stable structure.

As a method for cooling the motor of the counter-type turbo compressor, liquid refrigerant at a cold temperature is injected into the motor unit. Its advantage is that it can quickly and reliably lower the temperature of the motor. However, there is a disadvantage in that the refrigerant performance of the entire refrigeration cycle may be partially reduced by partially bypassing the refrigerant of the refrigeration cycle and using it for motor cooling.

As a method of cooling the motor while compensating for these disadvantages, there is a method of arranging all the impellers on one side of the motor. When the impeller is arranged in this way, the refrigerant sucked into the impeller passes through the motor to cool the motor and is sucked into the impeller. Thus, no additional injection lines are required, eliminating the disadvantages of counter-type injection cooling. In addition, since gaseous suction refrigerant is used instead of cold liquid refrigerant, there is no problem of reliability or reduction in efficiency of the aerodynamic part due to inflow of liquid refrigerant.

Turbo compressors have a certain relationship between the operating speed and the maximum pressure ratio. In addition, there is a certain relationship between the operating speed and the flow rate. Due to these characteristics, there is a problem in that it is difficult to have a required flow rate range in all pressure ratios when designing three or more stages.

In particular, in order to have a flow rate range of 10 to 100% of partial load at a pressure ratio of 15 or more, all compression parts of the first to third stages do not compress sequentially, but only two compression parts are compressed sequentially, and one compression part is bypassed by suction or cycle (by-pass) and the development of technology to secure the operating range is required.

Among conventional turbocompressors, Patent Document 1 (EP 2019192850 (2020.02.26.)) discloses a turbocompressor having an axial bearing cooling arrangement structure.

Patent Document 1, as a solution to the problem of deformation of the thrust bearing plate due to heat generation in the thrust bearing and vibration of the shaft caused by this, forms a suction refrigerant bypass passage adjacent to the thrust bearing plate to cool the thrust bearing part. Provides a structure that prevents thermal deformation of the thrust bearing plate through. Further, for the inlet distributor having an inlet refrigerant flow path, the inlet distributor is configured to cool adjacent to the thrust bearing plate, includes a bypass opening, and a part of the suction refrigerant introduced through the bypass opening cools the thrust plate. A structure that joins the suction refrigerant again is disclosed.

In the case of Patent Document 1, it is difficult to manufacture and assemble the shape of the guide that distributes the suction refrigerant into the first-stage compression unit, and the efficiency of the compressor decreases due to flow resistance, and the inflow of high density refrigerant depends on the operating conditions of the compressor. When distributed for the purpose of bearing cooling, there is a problem of generating heat rather than cooling.

In addition, in the case of Patent Document 1, in order to cool the motor and the bearing part, a liquid refrigerant is put in and the liquid refrigerant having a high density is expanded and introduced into the suction part due to the characteristics of the horizontal compressor in implementing the stirring well. there is a problem.

Meanwhile, Patent Document 2 (US 7293954 (November 13, 2007)) predicts surge of a turbo compressor and discloses a control system for preventing surge. As a method of controlling the surge, a high-temperature gas bypass is used. A bypass pipe connects a discharge part and a suction part, and a bypass valve enabling opening and closing of the bypass pipe is applied. In addition, Patent Document 2 discloses a feature of opening and closing the bypass valve of the hot gas at a predetermined value through a control device when it is determined that a surge occurs in the anti-surge control system.

In Patent Document 2, when the high-temperature gas bypass is applied, the high-temperature and high-pressure discharge gas of the discharge unit is mixed with the suction gas, thereby increasing the suction pressure and enabling surge avoidance.

In this way, when the hot gas is bypassed, the temperature of the suction refrigerant rises, which lowers the efficiency of the compressor and adversely affects the reliability of the mechanical unit. In particular, in the case of 3-stage compression, the pressure and temperature of the discharge gas discharged to the 3-stage compression unit are much higher than those of the 1-stage or 2-stage compressor, and the conventional high-temperature gas bypass is used to avoid surge in the 3-stage turbo compressor. If used, there is a problem that the temperature of the suction refrigerant rises excessively.

The present invention has been made to solve the above problems, and one object of the present invention is to provide a turbo compressor of a structure that can be miniaturized while paying a high compression ratio by a three-stage structure impeller and a method for controlling the same.

Another object of the present invention is to provide a turbo compressor and a method for controlling the same in which a flow rate range is not reduced while securing a pressure ratio by means of a three-stage impeller.

Another object of the present invention is a structure in which only the first and second stage compression units enable discharge and the third stage compression unit bypasses or sends refrigerant to the suction unit of the first stage compression unit to lower the operating speed and minimize losses. It is to provide a turbo compressor and a method for controlling the same.

Another object of the present invention is to provide a turbo compressor having a structure capable of having a required flow rate range at all pressure ratios when designed with three or more stages, and a method for controlling the same.

In order to solve the above problems, the turbo compressor of the present invention, a driving unit capable of generating rotational power for compression of the refrigerant; a shaft extending in one direction and installed in the driving unit to be rotatable by power generated from the driving unit; One side of the shaft includes first to third compression units installed on the shaft, and the first compression unit sucks the refrigerant discharged from the evaporator, compresses the sucked refrigerant, and discharges the refrigerant from the drive unit. and a first impeller rotating by the power of, and the second compression unit sucks in the refrigerant discharged from the first compression unit and compresses the sucked refrigerant so that it can be discharged by the power of the drive unit. A rotating second impeller is provided, and the third compression unit sucks the refrigerant discharged from the second compression unit, compresses the sucked refrigerant, and discharges the refrigerant to the outside or bypasses the first compression unit. 3 Impeller is provided.

According to an example related to the present invention, the first compression unit has a first inlet through which the refrigerant discharged from the evaporator can be sucked, and the first inlet communicates with the third impeller to enable supply of the refrigerant. A first bypass passage is connected, and a first valve enabling or blocking flow from the first inlet to the third impeller may be installed in the first bypass passage.

The first compression unit may include a first impeller housing capable of accommodating the first impeller, and the first inlet may be formed at one side of the first impeller housing in a direction parallel to the axis.

The second compression unit has a second outlet capable of supplying the refrigerant discharged from the second impeller to the third impeller, the third compression unit is capable of communicating with the second outlet, An inflow passage allowing the refrigerant discharged from the second impeller to flow into the third impeller is provided, and a second valve is installed at the second outlet or the inflow passage, and the second valve discharges the refrigerant from the second impeller. The flow of the refrigerant to the third impeller may be enabled or blocked.

A second impeller housing capable of accommodating the second impeller may be provided, and the second outlet may be provided in the second impeller housing.

According to another example related to the present invention, the third compression unit includes a third volute formed on a side of the third impeller to collect and discharge the refrigerant discharged from the third impeller, A second bypass passage may be formed between the first inlet and the third volute.

A third valve is installed in the second bypass passage, and the third valve enables or blocks the flow of the refrigerant discharged from the third impeller from the third volute to the first inlet. .

A third outlet communicating with an external cycle is formed in the third volute, a fourth valve is installed at the third outlet, and the fourth valve discharges the refrigerant discharged from the third impeller to an external cycle. can be enabled or blocked.

The drive unit may include a refrigerant inlet flow path capable of communicating with the first inlet, and a fifth valve may be connected to the refrigerant inlet flow path to enable or block the inflow of the refrigerant discharged from the evaporator.

In order to solve another of the above problems, the turbo compressor of the present invention includes a driving unit capable of generating rotational power for compressing a refrigerant; a shaft extending in one direction and installed in the driving unit to be rotatable by power generated from the driving unit; first to third compression units installed on the shaft at one side of the shaft; and a control unit electrically connected to the drive unit to control operations of the first to third compression units, wherein the first compression unit can suck in refrigerant discharged from the evaporator, compress the sucked refrigerant, and discharge the sucked refrigerant. And a first impeller rotating by power from the drive unit to do so, and the second compression unit sucks the refrigerant discharged from the first compression unit, compresses the sucked refrigerant, and discharges the refrigerant. It has a second impeller rotating by power from the unit, and the third compression unit sucks in the refrigerant discharged from the second compression unit, compresses the sucked refrigerant, and discharges it to the outside or to the first compression unit. A third impeller enabling bypass may be provided.

The first compression unit has a first inlet through which the refrigerant discharged from the evaporator can be sucked, and a first bypass flow path communicating to enable supply of refrigerant to the third impeller is connected to the first inlet. , A first valve enabling or blocking the flow from the first inlet to the third impeller may be installed in the first bypass passage.

The second compression unit has a second outlet capable of providing the refrigerant discharged from the second impeller to the third compression unit, and the third compression unit is capable of communicating with the second outlet, An inflow passage allowing the refrigerant discharged from the second impeller to flow into the third impeller is provided, and a second valve is installed at the second outlet or the inflow passage, and the second valve discharges the refrigerant from the second impeller. The flow of the refrigerant to the third impeller may be enabled or blocked.

According to an example related to the present invention, the third compression unit includes a third volute formed on a side of the third impeller to collect and discharge the refrigerant discharged from the third impeller, wherein the first A second bypass passage may be formed between the inlet and the third volute.

The control unit is electrically connected to the first valve and can control the first valve to be turned off when a target pressure ratio is not greater than an operable pressure ratio or when a surge is not expected.

The control unit is electrically connected to the second valve and can control the second valve to be turned off when a target pressure ratio is not greater than an operable pressure ratio or when a surge is not expected.

According to another example related to the present invention, a third valve is installed in the second bypass passage, and the third valve allows the refrigerant discharged from the third impeller to flow from the third volute to the first inlet. It can enable or block the flow.

The control unit is electrically connected to the third valve, and the third valve is turned off when the target pressure ratio is not greater than the operable pressure ratio or when a surge is not expected, and the target pressure ratio is greater than the operable pressure ratio. The third valve may be controlled to be turned on when a surge or a surge is expected.

The control unit is electrically connected to the fourth valve and can control the fourth valve to be turned off when a target pressure ratio is not greater than an operable pressure ratio or when a surge is not expected.

The drive unit may include a refrigerant inlet passage capable of communicating with the first inlet, and a fifth valve may be installed in the refrigerant inlet passage to enable or block the inflow of the refrigerant discharged from the evaporator.

The control unit is electrically connected to the fifth valve and controls the fifth valve to be turned off when the target pressure ratio is not greater than the operable pressure ratio or when a surge is not expected, and the target flow rate is operated. The fifth valve may be controlled to be turned on when heating is performed without being greater than the available flow rate and the response to the injection load is possible.

In order to solve the above another problem, a method for controlling a turbo compressor of the present invention includes determining whether a target flow rate is greater than an operable flow rate; determining whether the target pressure ratio is greater than the operable pressure ratio; Determining whether a surge is expected; and determining whether to perform cooling or heating.

When it is decided to perform cooling, the operation of the compressor is controlled to be stopped.

When the target pressure ratio is smaller than the operable pressure ratio, the third compression unit operates, and when the third compression unit operates, the first to fifth valves are turned off to discharge the refrigerant Response operation according to the load is performed so that

When the surge is not expected to occur, the second compression unit is operated, and when the second compression unit is operated, the second and third valves are turned off to discharge the refrigerant Responsive operation according to the load.

In the present invention, only the first and second stage compression units enable discharge, and the third stage compression unit bypasses or sends the refrigerant to the suction unit of the first stage compression unit to lower the operating speed and thereby minimize losses.

In addition, the present invention, at a pressure ratio of 15 or more, compresses only the compression parts of the first and second stages sequentially without sequentially compressing all the compression units of the first to third stages so as to have a flow rate range of 10% to 100% of partial load. The compression part of the bypass bypasses the intake or cycle to secure the operating range.

In the present invention, the surge margin valve can be applied in this way, and operates to avoid the operating speed when the surge point of the turbocompressor of the present invention is unstable or acts as a safety valve only for the turbocompressor other than the bypass of the cycle. This makes it possible to respond to driving in real time.

In the present invention, by adjusting the operation characteristics of various valves, it is possible to minimize the concern that a large amount of refrigerant used for cooling at high speed enters the first stage inlet and compresses the liquid without the refrigerant distributor mentioned in the prior art. can improve

In addition, the present invention directly bypasses the first-stage compression unit in the third-stage compression unit, so that an additional valve is required, but the flow rate of the turbo compressor is increased to have a larger operating range than the choking area. Therefore, it can be applied to various products by expanding the rated capacity without increasing the operating speed.

In addition, according to the present invention, the method of discarding the refrigerant by bypassing from the 3-stage compression unit to the external cycle can simplify the flow path (for example, piping), thereby securing an operating range.

1 is a cross-sectional view showing a turbo compressor of the present invention.

Figure 2 is a conceptual diagram schematically showing the flow, suction and discharge of refrigerant in the turbo compressor of the present invention.

3 is a conceptual diagram showing first to third compression units in the turbo compressor of the present invention;

4 is a block diagram showing an electrical connection relationship with a driving unit, first to third compression units, and first to fifth valves of a control unit;

5 is a flowchart showing operations aimed at low flow rate and high pressure ratio operation of the turbocompressor of the present invention.

Fig. 6 is a flow chart showing operations aimed at low flow rate and medium pressure ratio operation of the turbocompressor of the present invention.

Fig. 7 is a flow chart showing operations aimed at high flow rate and low pressure ratio operation of the turbocompressor of the present invention.

8 is a graph showing flow rate, pressure ratio, and surge line by comparing the three-stage turbocompressor of the present invention and the conventional two-stage turbocompressor.

In this specification, the same or similar reference numerals are given to the same or similar components even in different embodiments, and overlapping descriptions thereof will be omitted.

In addition, a structure applied to one embodiment may be equally applied to another embodiment as long as there is no structural or functional contradiction between different embodiments.

Singular expressions include plural expressions unless the context clearly dictates otherwise.

In describing the embodiments disclosed in this specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed descriptions thereof will be omitted.

The accompanying drawings are only for easy understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the accompanying drawings, and all changes and equivalents included in the spirit and technical scope of the present invention are included. It should be understood to include water or substitutes.

Hereinafter, the turbo compressor 100 according to the present invention will be described in detail based on an embodiment shown in the accompanying drawings.

1 is a cross-sectional view showing a turbo compressor 100 of the present invention. Referring to FIG. 1 , the turbo compressor 100 of the present invention includes a driving unit 120, a shaft 125, and first to

third compression units

130, 140, and 180.

The drive unit 120 can generate rotational power for compression of the refrigerant. The driving unit 120 includes a stator 121 and a rotor 122, and a detailed structure thereof will be described later.

The shaft 125 extends in one direction and is rotated by power generated from the drive unit 120 .

The first to

third compression units

130, 140, and 180 are installed on the shaft 125 at one side of the shaft 125, and each of the first to

third compression units

130, 140, and 180 and first to

third impellers

131, 141, and 181 enabling compression (125) of the refrigerant.

The first compression unit 130 includes a first impeller 131 that rotates by power from the drive unit 120 to suck in the refrigerant discharged from the evaporator, compress the sucked refrigerant, and enable discharge.

In addition, the second compression unit 140 sucks in the refrigerant discharged from the first compression unit 130, compresses the sucked refrigerant, and rotates the second impeller by power from the driving unit 120 to enable discharge. (141) is provided.

On the other hand, the third compression unit 180 sucks in the refrigerant discharged from the second compression unit 140, compresses the sucked refrigerant, discharges it to the outside, or bypasses the first compression unit to provide a third compression unit. An impeller 181 is provided.

By the refrigerant compression 125 of the first and

second compression units

130 and 140, the third compression unit 180 receives suction refrigerant and bypasses it to the housing or cycle, thereby minimizing loss and providing a wide operating range. have.

The third compression unit 180 is configured to compress the high-density refrigerant after being compressed in the first and

second compression units

130 and 140, so that a relatively large flow rate is achieved when the refrigerant is compressed in the first compression unit 130. It is not necessary to compress, and the refrigerant compressed in the third compression unit 180 can be supplied again to the rear end of the evaporator, which is the inlet of the housing, so that loss can be minimized.

In addition, since the flow rate and pressure ratio increase at the target speed for the target pressure ratio through the first to

third compression units

130, 140, and 180, the operation speed is lowered to ensure efficiency improvement.

In addition, this method reduces the flow rate and pressure ratio at the same operating speed compared to the method of performing three-stage compression through the first to

third compression units

130, 140, and 180, but it is possible to secure an operating range while minimizing surge point operation. there will be

In the case of the conventional two-stage turbo compressor 100, since the hot gas by-pass sucks the discharged refrigerant compressed in the second stage back into the first-stage compression unit, the temperature and pressure increase relatively rapidly. Therefore, there is a problem that the flow rate of the bypass is limited. On the other hand, in the turbo compressor 100 of the present invention, since the refrigerant compressed through the third compression unit 180 is supplied back to the first and

second compression units

130 and 140, the temperature and pressure are relatively increased. It is possible to minimize, and it is possible to have a design margin for the surge characteristic that the turbo compressor 100 generally has.

In addition, in the present invention, the surge margin valve can be applied in this way, and operates to avoid the operating speed at the time of unstable operation of the surge point of the turbo compressor 100 of the present invention or the turbo compressor other than the bypass of the cycle ( 100) as a safety valve, enabling real-time operation response.

Detailed structures of the first to

third compression units

130 , 140 , and 180 and the first to

third impellers

131 , 141 , and 181 provided thereto will be described later.

The turbo compressor 100 of the present invention may further include a casing 110. In the casing 110, the drive unit 120 is installed in the inner space, the first compression unit 130 and the second compression unit 140 are installed outside the casing 110, and the drive unit 120 and A shaft 125 is connected between the

compression units

130 and 140 .

Referring to FIG. 1, in the turbo compressor 100 according to the present embodiment, the drive unit 120 is installed in the inner space of the casing 110, and the first compression unit 130 and the outside of the casing 110 are installed. A second compression unit 140 is installed, and an example in which a shaft 125 is connected between the drive unit 120 and the

compression units

130 and 140 is shown.

The casing 110 may include a shell 111 having a cylindrical shape with both ends open, and a front frame 112 and a rear frame 113 covering both open ends of the shell 111, respectively.

A stator 121 of a driving unit 120 to be described later is fixedly coupled to the inner circumferential surface of the shell 111, and a shaft 125 to be described later passes through the center of the front frame 112 and the rear frame 113.

Holes

112a and 113a are formed, respectively, and the hole 112a of the front frame 112 and the hole 113a of the rear frame 113 are radial bearings for supporting the shaft 125 in the radial direction (151, 152) can be installed respectively.

In addition, a first thrust bearing 153 is coupled to the inner surface of the front frame 112 and a second thrust bearing 154 is coupled to the inner surface of the rear frame 113, respectively. The first axial support plate (thrust runner) 161 and the second axial support plate (thrust runner 162) may be fixedly coupled to each other so as to face the thrust bearing 153 and the second thrust bearing 154, respectively. That is, the first thrust bearing 153 together with the first axial support plate 161 forms a first direction thrust limiter, and the second thrust bearing 154 together with the second axial support plate (thrust runner 162) A second direction thrust limiting portion is formed. Thus, the first direction thrust limiting unit and the second direction thrust limiting unit cancel thrust on the rotating element including the shaft 125 while forming thrust bearings in opposite directions.

Meanwhile, the driving unit 120 serves to generate rotational power for compressing the refrigerant. The driving unit 120 includes a stator 121 and a rotor 122, and at the center of the rotor 122, the rotational force of the rotor 122 is transferred to a first impeller 131 and a second impeller 141, which will be described later. A shaft 125 for transmission is coupled.

The stator 121 may be fixed by being press-fitted to the inner circumferential surface of the casing 110 or welded to the casing 110 . For example, the outer circumferential surface of the stator 121 is formed to be decut in a D shape, and a passage through which fluid can move may be formed between the inner circumferential surface of the casing 110.

The rotor 122 is located inside the stator 121 and is spaced apart from the stator 121 . Balance weights may be coupled to both ends of the rotor 122 in the axial direction to offset eccentric loads generated by the first impeller 131 and the second impeller 141, which will be described later. However, the balance weight may be coupled to the shaft 125 without being installed on the rotor 122 .

A refrigerant inlet passage 182f may be formed in the driving unit 120 to allow the inflow of refrigerant discharged from the evaporator, and its structure will be described later.

When the balance weight is coupled to the shaft 125, the first axial support plate 161 and the second axial support plate (thrust runner) 162 may be used as the balance weight.

The shaft 125 is press-fitted through the center of the rotor 122 . Therefore, the shaft 125 receives rotational force generated by the interaction between the stator 121 and the rotor 122 and rotates together with the rotor 122, and this rotational force is transmitted to the first impeller 131 and the second impeller to be described later. (141) to inhale, compress and discharge the refrigerant.

On both sides of the shaft 125, that is, on both sides of the rotor 122, a first axial support plate 161 axially supported by first and

second thrust bearings

153 and 154 provided in the casing 110 and The second axial support plates (thrust runners, 162) are fixedly coupled to each other. Accordingly, as described above, the shaft 125 is a first thrust bearing (where the first axial support plate 161 and the second axial support plate 162 provided on the shaft 125 are provided on the casing 110), as described above. 153) and the second thrust bearing 154, it is possible to effectively cancel the thrust generated by the first compression unit 130 and the second compression unit 140 while being supported in opposite directions.

The first axial support plate 161 and the second axial support plate 162 may be integrally provided at both ends of the rotor 122, but in this case, the first axial support plate 161 and the second axial support plate 162 ) Frictional heat generated in the process of supporting the shaft 125 in the axial direction may be transmitted to the rotor 122, and when each

support plate

161, 162 is deformed by receiving a load in the axial direction, the rotor 122 may be transformed. Accordingly, it is preferable that the first axial support plate 161 and the second axial support plate 162 are spaced apart from both ends of the rotor 122 .

In addition, when the first axial support plate 161 and the second axial support plate 162 are fixedly coupled to the shaft 125 to be described later, as described above, the first axial support plate 161 and the second axial support plate It may be used as a balance weight by adjusting the weight or fixing position of (162). In this case, since there is no need to install a separate balance weight on the rotor 122, not only can the weight of the rotating element be reduced, but also the axial length of the turbo compressor 100 can be reduced, thereby miniaturizing the turbo compressor 100. can

Here, the first thrust bearing 153 and the second thrust bearing 154 are not installed on the front frame 112 and the rear frame 113, but on the first axial support plate 161 and the second shaft opposite to each other. It may also be installed on the direction support plate 162 .

In addition, the inside of the casing 110, that is, between the front frame 112 and the rotor 122 or between the rear frame 113 and the rotor 122 is a separate front side fixed to the casing 110, respectively. A side fixing plate (not shown) and a rear fixing plate (not shown) may be further provided, and the first thrust bearing 153 and the second thrust bearing 154 may be respectively installed on the front fixing plate and the rear fixing plate. In this case, although the axial length of the turbo compressor 100 may increase and the number of assembly man-hours may increase, reliability may be improved compared to installing a thrust bearing directly on the casing 110.

Here, although not shown, the first thrust bearing 153 and the second thrust bearing 154 are gathered on one side of the drive unit 120, that is, on either the front side or the rear side with respect to the stator 121. may be provided.

Meanwhile, the

compression units

130, 140, and 180 may be formed of one compression unit to perform single compression, but may be formed of a plurality of compression units to perform multi-stage compression as in the present embodiment. In the case of the multi-stage compression 125, the plurality of

compression units

130, 140, and 180 are installed on both sides of the casing 110 with respect to the drive unit 120 to improve the characteristics of the turbo compressor 100 having a large axial load. Considering this, it can be desirable in terms of reliability.

However, in the case of the opposite type in which a plurality of compression units are installed on both sides, the length of the compressor becomes long and the compression efficiency may decrease. Forming on one side may be preferable in terms of high efficiency and miniaturization. Hereinafter, when a plurality of compression units are provided to compress the refrigerant in multiple stages, first to

third compression units

130, 140, and 180 will be separately described according to the order of compressing the refrigerant.

The first compression unit 130 and the second compression unit 140 are installed consecutively along the axial direction on one side of the casing 110 .

In addition, the first and

second impellers

131 and 141 are disposed to face the same direction so that the refrigerant flows from the right side of the first compression unit 130 and the second compression unit 140.

The first compression unit 130 includes a first inlet 132b through which the refrigerant discharged from the evaporator can be sucked. In addition, the first compression unit 130 may include a first impeller housing 132 capable of accommodating the first impeller 131, the first inlet 132b is, for example, the first impeller housing ( 132) may be formed on one side. 1 shows an example in which the first inlet 132b is formed in a direction parallel to the axis in the first impeller housing 132 near the center of the turbo compressor 100.

The first inlet 132b is connected to a first bypass passage 182d communicating to enable the supply of refrigerant to the third impeller 181, and the first bypass passage 182d has the first inlet ( A first valve 191a enabling or blocking the flow from 132b) to the impeller 181 may be installed.

In addition, the first inlet 132b may be formed on one side of the first impeller housing 132 in a direction parallel to the axis.

The first valve 191a may be understood as a first bypass valve.

Looking near the upper side of FIG. 1, the first bypass passage 182d is formed in an “L” shape in the first impeller housing 132, the second impeller housing 142, and the third impeller housing 182. An example is shown, but it is not necessarily limited to this structure, and may be formed in other structures or configurations as long as the first inlet 132b and the inflow passage 182f of the third compression unit 180 can communicate.

In the first compression unit 130, the second compression unit 140, and the third compression unit 180, each of the

impellers

131, 141, and 181 are accommodated in the

respective impeller housings

132, 142, and 182 and coupled. It can be. That is, in the first compression unit 130, the first impeller 131 is accommodated in the first impeller housing 132 and coupled to the shaft 125, and the second compression unit 140 has a second impeller 141 The second impeller housing 142 is accommodated and coupled to the shaft 125, and the third compression unit 180 is accommodated in the third impeller housing 182 and coupled to the shaft 125. can However, in some cases, the first impeller 131, the second impeller 141, and the third impeller 181 may be continuously arranged in one impeller housing and coupled to the shaft 125. However, if a plurality of impellers are installed in one impeller housing, the shape of the impeller housing will be considerably complicated.

Here, in this embodiment, a multi-stage turbo compressor 100 in which a plurality of impellers are successively installed on one side in the axial direction with respect to the driving unit 120 (or casing 110) will be described as an example.

A first impeller accommodating space 132a in which the first impeller 131 is accommodated is formed inside the first impeller housing 132, and a suction pipe 115 is connected to one end of the first impeller housing 132 to cycle the refrigeration cycle. A first inlet 132b through which refrigerant is sucked from the evaporator is formed, and at the other end of the first impeller housing 132, a first outlet 132c guides the refrigerant compressed in the first stage to the second impeller housing 142 to be described later. ) is formed.

The first impeller accommodating space 132a may be formed in a closed shape except for the first inlet 132b and the first outlet 132c so as to completely accommodate the first impeller 131, but the first impeller 131 It may be formed in a semi-enclosed shape in which the rear side of the is opened and the open side is sealed to the front side of the second impeller housing 142 to be described later.

Between the first inlet 132b and the first outlet 132c, the first diffuser 133 is formed by being spaced apart from the outer circumferential surface of the wing 131b of the first impeller 131 by a predetermined interval, and the first diffuser 133 The first volute 134 is formed on the downstream side of ). In addition, the first inlet 132b is formed at the center of one end of the first diffuser 133 in the axial direction, and the first outlet 132c is formed at the downstream side of the first volute 134, respectively.

The first impeller 131 includes a first disc portion 131a coupled to the shaft 125 and a plurality of first wing portions 131b formed on the front surface of the first disc portion 131a. The first disc portion 131a has a plurality of first wing portions 131b formed in a conical shape on its front surface, but its rear surface may be formed in a flat plate shape to receive back pressure.

Here, a first back pressure plate (not shown) coupled to the shaft 125 is provided at the rear of the first disk part 131a and is spaced apart by a predetermined interval, and a first sealing member having an annular shape is attached to the first back pressure plate. (not shown) may be provided. Accordingly, a first back pressure space (not shown) filled with a predetermined refrigerant may be formed between the front surface of the second impeller housing 142 and the first back pressure plate at the rear of the first disc unit. However, since the pressure of the refrigerant sucked through the first inlet 132b is not so high, the thrust to the shaft 125 may not be large, so the first back pressure space may be excluded.

The second compression unit 140 may have a second outlet 142d that enables the refrigerant discharged from the second impeller 141 to be provided to the third impeller 181 . For example, as will be described later, the second outlet 142d may be provided in the second impeller housing 142 . Also, the third compression unit 180 may include an inflow passage 182f. The inflow passage 182f may communicate with the second outlet 142d and may include an inflow passage 182f allowing the refrigerant discharged from the second impeller 141 to flow into the third impeller 181. .

A second valve 191b may be installed in the second outlet 142d or the inflow passage 182f to enable or block the flow of the refrigerant discharged from the second impeller 141 to the third impeller 181. can

The second valve 191b may be understood as an inflow valve that introduces or blocks the flow of the refrigerant discharged from the second impeller 141 to the third impeller 181 .

1 shows an example in which the second outlet 142d is provided in the second volute and the second valve 191b is installed in the inflow passage 182f. However, it is not necessarily limited to this structure, and the second valve 191b may be installed on the side of the second outlet 142d.

Meanwhile, a second impeller accommodating space 142a in which the second impeller 141 is accommodated is formed inside the second impeller housing 142, and one end of the second impeller housing 142 has a first impeller housing 132 is connected to the first outlet 132c of the second inlet 142b through which the first-stage compressed refrigerant is sucked, and a discharge pipe 116 is connected to the other end of the second impeller housing 142 to form a second-stage compressed refrigerant. A second discharge port 142c is formed to guide the refrigerant to the condenser of the refrigerating cycle.

A second diffuser 143 is formed between the second inlet 142b and the second outlet 142c by being spaced apart from the outer circumferential surface of the wing 141b of the second impeller 141 by a predetermined interval, and the second diffuser 143 The second volute 144 is formed on the downstream side of ). In addition, the second inlet 142b is formed at the center of one end of the second diffuser 143 in the axial direction, and the second outlet 142c is formed at the downstream side of the second volute 144, respectively.

The second impeller 141 includes a second disk portion 141a coupled to the shaft 125 and a plurality of second wing portions 141b formed on the front surface of the second disk portion 141a. The second disc portion 141a has a plurality of second wing portions 141b formed in a conical shape on its front surface, but its rear surface may be formed in a flat plate shape to receive back pressure.

Here, a second back pressure plate 145 coupled to the shaft 125 is provided at the rear of the second disk part 141a and is spaced apart by a predetermined interval, and the second back pressure plate 145 has an annular second back plate 145. A sealing groove 145a is formed, and the second sealing member 146 may be inserted into the second sealing groove 145a. Thus, a second back pressure space (not shown) filled with a predetermined refrigerant is formed between the second back pressure plate (not shown) and the front surface of the casing 110 at the rear of the second disc portion 141a. In addition, as a part of the refrigerant flowing into the second back pressure space flows into the second sealing groove (not shown) and pushes up the second sealing member (not shown), the second back pressure space is sealed.

The second back pressure space is connected to a back pressure passage to be described later, and the back pressure passage is selectively connected to the back pressure passage so that the pressure in the second back pressure space can be varied according to the operating speed (ie, compression ratio) of the compressor. A back pressure control valve that opens and closes may be installed.

For example, the back pressure passage may be formed through the inside of the second impeller housing 142 and the casing 110 . That is, a first back pressure passage is formed inside the housing constituting the wall of the second impeller housing 142, and a second back pressure passage communicates with the first back pressure passage inside the front frame 112 of the casing 110. can be formed. Of course, the back pressure flow path may be formed in the form of a pipe branched from the middle of the discharge pipe, but it may be preferable to form the back pressure flow path inside the impeller housing and the front frame to reduce manufacturing cost by reducing the number of parts.

However, in some cases, the back pressure passage may be formed by assembling a separate valve frame equipped with the back pressure passage to the front surface of the casing 110 .

The third compression unit 180 is disposed adjacent to the second compression unit 140 .

The third compression unit 180 is installed on one side of the casing 110 opposite to the position where the drive unit 120 is disposed.

That is, in the third compression unit 180, the third impeller 181 is accommodated in the third impeller housing 182 and coupled to the shaft 125.

As shown in FIG. 1, the third impeller 181 is disposed to face opposite to the first and

second impellers

131 and 141.

Meanwhile, a third impeller receiving space 182a in which the third impeller 181 is accommodated is formed inside the third impeller housing 182, and at one end of the third impeller housing 182, the second compression unit 140 A third inlet 182b through which the refrigerant discharged from is provided is formed, and a third discharge port 182c for discharging the refrigerant compressed in three stages is formed on the lower side of the third impeller housing 182 .

The third impeller accommodating space 182a may be formed in a closed shape except for the third inlet 182b and the third discharge port 182c so as to completely accommodate the third impeller 181, but the third impeller 181 It may be formed in a semi-enclosed shape in which the rear side of the is opened and the open side is sealed to the rear side of the second impeller housing 142 to be described later.

A third diffuser 183 is formed between the third inlet 182b and the third discharge port 182c by being spaced apart from the outer circumferential surface of the wing 181b of the third impeller 181 by a predetermined distance, and the third diffuser 183 A third volute 184 is formed on the downstream side of ). Also, a third inlet 182b is formed at the center of one end of the third diffuser 183 in the axial direction, and a third discharge port 182c is formed at the downstream side of the third volute 184, respectively.

The third impeller 181 includes a third disc portion 181a coupled to the shaft 125 and a plurality of third wing portions 181b formed on the front surface of the third disc portion 181a. The third disc portion 181a has a plurality of third wing portions 181b formed in a conical shape on its front surface, but its rear surface may be formed in a flat plate shape to receive back pressure.

Here, a back pressure plate (not shown) coupled to the shaft 125 is spaced apart from each other by a predetermined interval at the rear of the third disc portion 181a, and an annular sealing member (not shown) is provided on the back pressure plate. It can be. Accordingly, a back pressure space (not shown) filled with a predetermined refrigerant may be formed between the rear surface of the second impeller housing 142 and the back pressure plate at the rear of the third disc unit.

The third compression unit 180 may include a third volute 184 capable of discharging the refrigerant discharged from the third impeller 181 . A second bypass passage 182e may be formed between the aforementioned first inlet 132b and the third volute 184 .

In addition, a third valve 191c may be installed in the second bypass flow path 182e, and the third valve 191c allows the refrigerant discharged from the third impeller 181 to flow through the third volute. The flow from 184 to the first inlet 132b is allowed or blocked.

The third valve 191c may be understood as a second bypass valve installed in the second bypass flow path 182e.

In addition, a third outlet 182g communicating with an external cycle is formed in the third volute 184, a fourth valve 191d is installed in the third outlet 182g, and the fourth valve 191d ) may enable or block the refrigerant discharged from the third impeller 181 from being discharged to an external cycle.

The fourth valve 191d may be understood as a third bypass valve installed in the third bypass passage.

1 shows an example in which a third outlet 182g is formed in the left direction in the third impeller housing 182, the third outlet 182g may communicate with an external cycle, and the third outlet 182g has An example in which the fourth valve 191d is installed is shown.

In this way, in the present invention, a third outlet 182g communicating with an external cycle is formed in the third volute 184, a fourth valve 191d is installed in the third outlet 182g, and The third outlet (182g) may communicate with an external cycle, and by the configuration in which the fourth valve (191d) is installed at the third outlet (182g), at a pressure ratio of 15 or more, at a partial load of 10% to 100% To have a flow rate range, all compression units in stages 1 to 3 do not compress sequentially, but only compression units in stages 1 and 2 are sequentially compressed, and the compression unit in 3 stages is bypassed with suction or cycle to secure an operating range.

As described above, the turbo compressor 100 of the present invention has a multi-stage structure in which a plurality of

impellers

131, 141, and 181 are successively installed on one side in the axial direction with respect to the driving unit 120 (or casing 110). The turbo compressor 100 of will be described as an example.

As shown in FIG. 1, a third impeller accommodating space 182a in which the third impeller 181 is accommodated is formed inside the third impeller housing 182, and one end of the third impeller housing 182 is inlet A flow path 182f is provided to receive the refrigerant discharged from the second compression unit 140, and the other end of the third impeller housing 182 discharges the refrigerant compressed by the third impeller 181. A third outlet 182g and a third outlet 182c are formed.

Meanwhile, the drive unit 120 may include a refrigerant inlet passage 182f capable of communicating with the first inlet 132b, and a fifth valve 191e may be connected to the refrigerant inlet passage 182f. The refrigerant inlet passage 182f may be formed along at least one direction, for example.

The fifth valve 191e may be understood as an injection valve that supplies refrigerant from the evaporator to the inside of the turbo compressor 100 .

1, an example in which a refrigerant inlet passage 182f is formed in the stator 121 of the driving unit 120 is shown. For example, the refrigerant inlet passage 182f is formed in a diagonal direction of the stator 121. Examples are shown, but are not necessarily limited to these structures.

1 shows an example in which an inlet communicating with the refrigerant inlet passage 182f is formed in the casing 110 and a fifth valve 191e is installed in the inlet.

The fifth valve 191e allows the refrigerant discharged from the evaporator to flow into or block the turbo compressor 100 .

A valve space (not shown) having a predetermined depth in the radial direction is formed in the front frame 112 of the casing 110, a back pressure valve (not shown) may be inserted and installed, and between the valve space and the back pressure valve A valve spring (not shown) may be installed to elastically support the back pressure valve.

In addition, a second back pressure hole (not shown) may be formed at one side of the first back pressure hole (not shown) to communicate the valve space with the inner space of the casing 110 . The second back pressure hole is formed to be located more centrally than the first back pressure hole so that it can be opened when a higher pressure than the first back pressure hole is received when the back pressure valve is opened by pressure. However, in some cases, the second back pressure hole may be formed at the same position as the first back pressure hole, that is, at a position where the first back pressure hole and the second back pressure hole are simultaneously opened and closed, or may be formed further outside the first back pressure hole. may be

The back pressure valve may be composed of a ball valve or a piston valve. The back pressure valve may have three positions depending on the difference between the force due to the pressure of the refrigerant flowing through the back pressure passage and the force due to the elastic force of the elastic member. That is, the back pressure valve has a first position where both the first back pressure hole and the second back pressure hole are closed, a second position where the first back pressure hole is open and the second back pressure hole is closed, and both the first back pressure hole and the second back pressure hole are open. It may be formed to have a third position.

To this end, the valve spring is composed of a compression coil spring and may be installed between the inner surface of the back pressure valve and the valve space. In some cases, the valve spring is composed of a tension coil spring and is installed between the outside of the back pressure valve and the valve space. may be installed.

Meanwhile, in the above-described embodiment, the first back pressure passage is connected to the discharge side of the second compression unit 140, that is, to the second discharge port, but in some cases, the back pressure passage may be connected to the discharge side of the first compression unit. Even in this case, basic configurations such as the valve space and the back pressure valve may be formed in the same manner as in the above-described embodiment.

The turbo compressor 100 according to the present embodiment as described above may be operated as follows.

That is, when power is applied to the driving unit 120, rotational force is generated by an induced current between the stator 121 and the rotor 122, and the rotational force causes the shaft 125 to rotate together with the rotor 122. will do The rotational force of the driving unit 120 is transmitted to the first impeller 131, the second impeller 141, and the third impeller 181 by the shaft 125, and the first impeller 131 and the second impeller 141 and the third impeller 181 rotate simultaneously in the respective

impeller receiving spaces

132a, 142a, and 182a.

Then, the refrigerant passing through the evaporator of the refrigeration cycle flows into the first impeller accommodation space 132a through the suction pipe and the first inlet 132b, and the refrigerant moves along the wing 131b of the first impeller 131. While doing so, the static pressure rises and at the same time passes through the first diffuser 133 with centrifugal force.

Then, the kinetic energy of the refrigerant passing through the first diffuser 133 leads to an increase in the pressure head by the centrifugal force in the first diffuser 133, and the centrifugally compressed high-temperature and high-pressure refrigerant flows in the first volute 134. It is collected and discharged through the first outlet 132c.

Then, while the refrigerant discharged from the first outlet 132c is transferred to the second impeller 141 through the second inlet 142b of the second impeller housing 142, the static pressure is restored inside the second impeller 141. As it rises, it passes through the second diffuser 143 with centrifugal force.

Then, the refrigerant passing through the second diffuser 143 is compressed to a desired pressure by the centrifugal force, and the high-temperature, high-pressure refrigerant compressed in two stages is collected in the second volute 144 and passed through the second outlet 142c and the discharge pipe. Through (not shown), a series of processes of being discharged to the condenser are repeated.

Meanwhile, some of the refrigerant passing through the second diffuser 143 and collected in the second volute 144 is provided to the third compression unit 180 . The refrigerant supplied to the third compression unit 180 flows along the inflow passage 182f of the third compression unit 180 and flows into the third impeller receiving space 182a through the third inlet 182b. do.

Then, while being transmitted to the third impeller 181, the static pressure rises again inside the third impeller 181 and at the same time passes through the second diffuser 183 with centrifugal force.

Then, the refrigerant passing through the third diffuser 183 is compressed to a desired pressure by centrifugal force, and the high-temperature, high-pressure refrigerant compressed in three stages is collected in the third volute 184 and part of the refrigerant is discharged through the third discharge port 182c. ) and a series of processes of being discharged to the condenser through a discharge pipe (not shown) are repeated.

Another part of the refrigerant collected in the third volute 184 may be supplied to an external cycle through the third outlet 182g.

In addition, another part of the refrigerant collected in the third volute 184 may be provided again to the first compression unit 130 by flowing through the second bypass passage 182e by the controller 170 to be described later. .

At this time, the first impeller 131 and the second impeller 141 provide thrust pushed backward by the refrigerant sucked through the first inlet 132b and the second inlet 142b of each of the

impeller housings

132 and 142. You will receive. In particular, in the case of the second impeller 141, as the refrigerant compressed in one stage by the first impeller 131 flows in through the second inlet 142b, it receives a considerably large backward thrust. This backward thrust is prevented by the first thrust bearing 153 and the second thrust bearing 154 provided inside the casing 110, so that the first impeller 131 and the second impeller 141 are connected to the shaft 125. ), and pushing toward the rear is suppressed.

As described above, when the first impeller 131 and the second impeller 141 are installed on one side with respect to the driving unit 120, a considerably large thrust is received toward the rear in the axial direction, thereby reducing the cross-sectional area of the thrust bearing. must be widely secured to maintain the reliability of the compressor. However, this increases the size of the turbo compressor 100 and increases the frictional loss in the thrust bearing, thereby degrading the efficiency of the compressor. In addition, during high-speed operation, the load of the drive unit 120 increases and the amount of heat generated increases, but this may not be effectively cooled or a separate cooling device may be required, resulting in an overall increase in manufacturing cost.

In view of this, the first impeller 131 and the second impeller 141 receive thrust to the rear, and the third impeller 181 also receives thrust to the rear, so that the first and

second impellers

131 and 141, Thrust forces of the third impeller 181 may be offset with each other, thereby reducing the load applied to the thrust bearing. Then, the size of the thrust bearing can be reduced, and the efficiency of the compressor can be increased by reducing the frictional loss caused by the thrust bearing.

In addition, although the amount of heat generated from the drive unit 120 may increase during high-speed operation, when a portion of the bypassed refrigerant is induced into the inner space of the casing 110 to cool the drive unit 120, the drive unit 120 ) to improve compressor efficiency.

4 shows the control unit 170, the drive unit 120, the first to

third compression units

130, 140, 180, and the first to

fifth valves

191a, 191b, 191c, 191d, 191e and electrical It is a block diagram showing the connection relationship.

As shown in FIG. 4 , the turbo compressor 100 of the present invention may further include a controller 170.

The controller 170 causes the turbo compressor 100 to operate or stop based on the target flow rate, the operable flow rate, the target pressure ratio, and the operable pressure ratio of the turbo compressor 100 .

As an example, the control unit 170 may include a controller or board on which a CPU or the like is mounted, but is not necessarily limited thereto. In addition, the control unit 170 may be understood as a configuration capable of storing and utilizing various logics or programs related to a control method described below.

The control unit 170 is electrically connected to the drive unit 120, the first to

third compression units

130, 140, and 180, and the first to

fifth valves

191a, 191b, 191c, 191d, and 191e, respectively. , and an example of this is shown in FIG.

The control unit 170 controls the first to

fifth valves

191a, 191b, 191c, 191d, in each case of low-flow/high-pressure ratio operation, low-flow/medium-pressure ratio operation, or high-flow/low-pressure ratio operation of the turbo compressor 100. 191e may be turned on or off, or the second or

third compression unit

140 or 180 may compress the refrigerant to operate in response to a load.

On the other hand, in the turbocompressor control method (S100, S200, S300) of the present invention, the turbocompressor 100 based on the target flow rate, operable flow rate, target pressure ratio, and operable pressure ratio of the turbo compressor 100 by the control unit 170 ) drive or stop.

The turbo compressor control method (S100, S200, S300) of the present invention includes the step of determining whether the target flow rate is greater than the operable flow rate (S10, S210, S310), and the step of determining whether the target pressure ratio is greater than the operable pressure ratio. (S20, S220, S320), determining whether a surge is expected (S50, S250, S350), and determining whether to perform cooling or heating (S30, S230, S330).

In addition, in the turbo compressor control method (S100, S200, S300) of the present invention, in each case of low flow high pressure ratio operation, low flow medium pressure ratio operation or high flow low pressure ratio operation of the turbo compressor 100, the control unit 170 ), the first to

fifth valves

191a, 191b, 191c, 191d, and 191e are turned on or off, or the second or third compression unit compresses the refrigerant, thereby operating in response to the load. can do

An example in which the turbo compressor control method (S100, S200, and S300) of the present invention is performed by the controller 170 will be described with reference to flowcharts of FIGS. 5 to 7 below.

5 is a flow chart of an operation (S100) aimed at low flow rate and high pressure ratio operation of the turbo compressor 100 of the present invention.

The controller 170 determines whether the target flow rate is greater than the operable flow rate (S10), and if the target flow rate is greater than the operable flow rate (Yes), determines whether the target pressure ratio is greater than the operable pressure ratio (S20), If the target flow rate is smaller than the operable flow rate (No), it is determined whether to perform cooling or heating (S30).

When it is decided to perform cooling, the operation of the turbo compressor 100 is stopped (S35).

On the other hand, when it is decided to perform heating, it is determined whether the injection load can be responded to (S40), and if the injection load can be responded to (eg), the fifth valve 191e is turned on (S43) according to the load A response operation is performed (S70).

It is determined whether the target pressure ratio is greater than the operable pressure ratio (S20), and if the target pressure ratio is greater than the operable pressure ratio (Yes), whether or not a surge will occur is predicted (S50).

On the other hand, when the target pressure ratio is smaller than the operable pressure ratio (No), the third compression unit 180 operates (S55). When the third compression unit 180 operates, the first to

fifth valves

191a, 191b, 191c, 191d, and 191e are turned off (S57). In this case, discharge 2 in FIG. It is performed, and corresponding operation according to the load is performed (S70).

When it is expected that a surge will occur (Yes), the third valve 191c is turned on (S60) and corresponding operation according to the load is performed (S70).

On the other hand, when it is expected that no surge will occur (No), the third compression unit 180 operates (S55). When the third compression unit 180 operates, the first to

fifth valves

FIG. 6 is a flowchart of an operation (S200) aimed at low flow rate and medium pressure ratio operation of the turbo compressor 100 according to the present invention.

The controller 170 determines whether the target flow rate is greater than the operable flow rate (S210), and if the target flow rate is greater than the operable flow rate (Yes), determines whether the target pressure ratio is greater than the operable pressure ratio (S220), If the target flow rate is smaller than the operable flow rate (No), it is determined whether to perform cooling or heating (S230).

When it is decided to perform cooling, the operation of the turbo compressor 100 is stopped (S235).

On the other hand, when it is decided to perform heating, it is determined whether the injection load can be responded to (S240), and if the injection load can be responded to (eg), the fifth valve 191e is turned on (S243) according to the load A response operation is performed (S270).

It is determined whether the target pressure ratio is greater than the operable pressure ratio (S220), and if the target pressure ratio is greater than the operable pressure ratio (Yes), whether or not a surge will occur is predicted (S250).

On the other hand, it is determined whether the target pressure ratio is greater than the operable pressure ratio (S220), and if the target pressure ratio is less than the operable pressure ratio (No), the second compression unit 140 operates (S255). When the second compression unit 140 operates, the second and third valves 191c are turned off (S257). In this case, discharge 1 in FIG. 2 is performed, and according to the load A response operation is performed (S270).

In addition, when it is expected that a surge will occur (Yes), the third valve 191c is turned on (S260) and corresponding operation according to the load is performed (S270).

On the other hand, when it is expected that no surge will occur (No), the second compression unit 140 operates (S255). When the second compression unit 140 operates, the second and third valves 191c are turned off (S257). In this case, discharge 1 in FIG. 2 is performed, and according to the load A response operation is performed (S270).

In addition, when the second compression unit 140 operates (S255), the second valve 191b is turned off in the third compression unit 180, and the first valve 191a is turned on. , discharge 2 in FIG. 2 is performed or the fourth valve 191d is turned on to enable load response operation (S256).

Due to this, by the pressure difference between discharge 2 and discharge 1 in FIG. 2 , backflow of discharge from the entire system can be prevented, and damage to the system and surge in the refrigerant flow path can be prevented. To this end, a non-return valve (for example, a check valve) and a differential pressure valve may be installed.

7 shows a flow chart of an operation (S300) aimed at driving the turbo compressor 100 with a high flow rate and a low pressure ratio according to the present invention.

The controller 170 determines whether the target flow rate is greater than the operable flow rate (S310), and if the target flow rate is greater than the operable flow rate (Yes), determines whether the target pressure ratio is greater than the operable pressure ratio (S320), If the target flow rate is smaller than the operable flow rate (No), it is determined whether to perform cooling or heating (S330).

When it is decided to perform cooling, the third compression unit 180 determines whether or not it is possible to respond to the flow rate (S333), and if the response is not possible (No), the operation of the turbo compressor 100 is stopped (S335). . On the other hand, if the third compression unit 180 can respond to the flow rate (yes), the second valve 191b in the third compression unit 180 is turned off, and the first valve 191a is turned on. ) state, discharge 2 in FIG. 2 is performed or the fourth valve 191d is turned on to enable load response operation (S356).

On the other hand, when it is decided to perform heating, it is determined whether the injection load can be responded to (S340), and if the injection load can be responded to (eg), the fifth valve 191e is turned on (S343) according to the load Corresponding operation is performed (S370), and if the injection load is not responsive (No), the operation is stopped (S335).

Meanwhile, it is determined whether the target pressure ratio is greater than the operable pressure ratio (S320), and if the target pressure ratio is greater than the operable pressure ratio (Yes), whether or not a surge will occur is predicted (S350).

When a surge is expected to occur (Yes), the third valve 191c is turned on (S360) and corresponding operation is performed according to the load (S370).

On the other hand, when it is expected that no surge will occur (No), the second compression unit 140 operates (S355). When the second compression unit 140 operates, the second and

third valves

191b and 191c are turned off. In this case, discharge 1 in FIG. 2 is performed (S357), and Corresponding operation according to the load is performed (S370).

In addition, when the second compression unit 140 operates (S355), the second valve 191b is turned off in the third compression unit 180, and the first valve 191a is turned on. , discharge 2 in FIG. 2 is performed or the fourth valve 191d is turned on to enable load response operation (S356).

The turbo compressor 100 described above and the method for controlling it (S100, S200, S300) are not limited to the configuration and method of the above-described embodiments, but the embodiments are all of the embodiments so that various modifications can be made. Alternatively, some of them may be selectively combined.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential characteristics of the present invention. Accordingly, the above detailed description should not be construed as limiting in all respects and should be considered illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

The present invention can be used for a turbo compressor and a method for controlling the same.

Claims

a driving unit capable of generating rotational power for compression of the refrigerant;

a shaft extending in one direction and installed in the driving unit to be rotatable by power generated from the driving unit;

Including first to third compression units installed on the shaft at one side of the shaft,

The first compression unit includes a first impeller rotating by power from the driving unit to suck in the refrigerant discharged from the evaporator, compress the sucked refrigerant, and enable discharge,

The second compression unit includes a second impeller rotating by power from the drive unit to suck in the refrigerant discharged from the first compression unit and compress the sucked refrigerant to be discharged;

The third compression unit includes a third impeller that sucks in the refrigerant discharged from the second compression unit, compresses the sucked refrigerant, and discharges it to the outside or bypasses the first compression unit. turbo compressor.
According to claim 1,

The first compression unit has a first inlet through which the refrigerant discharged from the evaporator can be sucked, and a first bypass flow path communicating to enable supply of refrigerant to the third impeller is connected to the first inlet. , A turbocompressor, characterized in that a first valve is installed in the first bypass passage to enable or block the flow from the first inlet to the third impeller.
According to claim 2,

The first compression unit has a first impeller housing capable of accommodating the first impeller, and the first inlet is turbo, characterized in that formed on one side of the first impeller housing in a direction parallel to the axis compressor.
According to claim 1 or 2,

The second compression unit has a second outlet that enables the refrigerant discharged from the second impeller to be supplied to the third impeller,

The third compression unit is capable of communicating with the second outlet and has an inflow passage allowing the refrigerant discharged from the second impeller to flow into the third impeller,

A second valve is installed at the second outlet or the inflow passage, and the second valve enables or blocks the flow of the refrigerant discharged from the second impeller to the third impeller.
According to claim 4,

The third compression unit includes a third volute formed on a side of the third impeller to collect and discharge the refrigerant discharged from the third impeller,

A turbo compressor, characterized in that a second bypass passage is formed between the first inlet and the third volute.
According to claim 5,

A third valve is installed in the second bypass passage, and the third valve enables or blocks the flow of the refrigerant discharged from the third impeller from the third volute to the first inlet. turbo compressor made with.
According to claim 5,

A third outlet communicating with an external cycle is formed in the third volute, a fourth valve is installed at the third outlet, and the fourth valve discharges the refrigerant discharged from the third impeller to an external cycle. A turbocompressor, characterized in that enabling or blocking it.
According to claim 2,

The drive unit is provided with a refrigerant inlet passage capable of communicating with the first inlet, and a fifth valve that enables or blocks the inflow of the refrigerant discharged from the evaporator is connected to the refrigerant inlet passage. .
a driving unit capable of generating rotational power for compression of the refrigerant;

a shaft extending in one direction and installed in the driving unit to be rotatable by power generated from the driving unit;

first to third compression units installed on the shaft at one side of the shaft; and

A control unit electrically connected to the driving unit to control operations of the first to third compression units;

The first compression unit includes a first impeller rotating by power from the driving unit to suck in the refrigerant discharged from the evaporator, compress the sucked refrigerant, and enable discharge,

The second compression unit includes a second impeller rotating by power from the drive unit to suck in the refrigerant discharged from the first compression unit and compress the sucked refrigerant to be discharged;

The third compression unit includes a third impeller that sucks in the refrigerant discharged from the second compression unit, compresses the sucked refrigerant, and discharges it to the outside or bypasses the first compression unit. turbo compressor.
According to claim 9,

The first compression unit has a first inlet through which the refrigerant discharged from the evaporator can be sucked, and a first bypass flow path communicating to enable supply of refrigerant to the third impeller is connected to the first inlet. , A turbocompressor, characterized in that a first valve is installed in the first bypass passage to enable or block the flow from the first inlet to the third impeller.
The method of claim 9 or 10,

The second compression unit has a second outlet enabling the supply of the refrigerant discharged from the second impeller to the third compression unit,

The third compression unit is capable of communicating with the second outlet and has an inflow passage allowing the refrigerant discharged from the second impeller to flow into the third impeller,

A second valve is installed at the second outlet or the inflow passage, and the second valve enables or blocks the flow of the refrigerant discharged from the second impeller to the third impeller.
According to claim 10,

The third compression unit includes a third volute formed on a side of the third impeller to collect and discharge the refrigerant discharged from the third impeller,

A turbo compressor, characterized in that a second bypass passage is formed between the first inlet and the third volute.
According to claim 11,

The control unit,

electrically connected to the second valve;

A turbocompressor characterized in that the second valve is controlled to be in an off state when the target pressure ratio is not greater than the operable pressure ratio or when a surge is not expected.
According to claim 12,

A third valve is installed in the second bypass passage, and the third valve enables or blocks the flow of the refrigerant discharged from the third impeller from the third volute to the first inlet. turbo compressor made with.
According to claim 14,

The control unit,

electrically connected to the third valve,

The third valve is turned off when the target pressure ratio is not greater than the operable pressure ratio or when a surge is not expected,

A turbocompressor characterized in that the third valve is controlled to be in an on state when the target pressure ratio is greater than the operable pressure ratio or when a surge is expected.
According to claim 12,

A third outlet communicating with an external cycle is formed in the third volute, a fourth valve is installed at the third outlet, and the fourth valve discharges the refrigerant discharged from the third impeller to an external cycle. to enable or block

The control unit,

electrically connected to the fourth valve,

A turbocompressor characterized in that the fourth valve is controlled to be in an off state when the target pressure ratio is not greater than the operable pressure ratio or when a surge is not expected.
According to claim 12,

The driving unit is provided with a refrigerant inlet passage capable of communicating with the first inlet, and a fifth valve is installed in the refrigerant inlet passage to enable or block the inflow of the refrigerant discharged from the evaporator,

The control unit,

electrically connected to the fifth valve,

Control the fifth valve to be off when the target pressure ratio is not greater than the operable pressure ratio or when surge is not expected,

A turbocompressor characterized in that the fifth valve is controlled to be turned on when the target flow rate is not greater than the operable flow rate, heating is performed, and it is possible to respond to the injection load.
Determining whether the target flow rate is greater than the operable flow rate;

determining whether the target pressure ratio is greater than the operable pressure ratio;

Determining whether a surge is expected; and

A turbocompressor control method comprising the step of determining whether to perform cooling or heating.
According to claim 18,

When the target pressure ratio is smaller than the operable pressure ratio, the third compression unit operates, and when the third compression unit operates, the first to fifth valves are turned off to discharge the refrigerant A method of controlling a turbo compressor, characterized in that for corresponding operation according to the load so as to do so.
According to claim 18,

When the surge is not expected to occur, the second compression unit is operated, and when the second compression unit is operated, the second and third valves are turned off to discharge the refrigerant A method of controlling a turbo compressor, characterized in that for corresponding operation according to the load.