阅读说明：本技术 涡轮压缩机和包括该涡轮压缩机的涡轮冷却器 (Turbo compressor and turbo cooler including the same ) 是由 金哲民 郑琎熺 韩贤旭 黄义植 姜正浩 李熙雄 于 2020-06-24 设计创作，主要内容包括：涡轮压缩机和包括该涡轮压缩机的涡轮冷却器。该涡轮压缩机包括：外壳,所述外壳被配置为限定外观,所述外壳的前部设置有制冷剂吸入孔,制冷剂通过所述制冷剂吸入孔被引入；马达壳体,所述马达壳体被配置为限定容纳空间,在该容纳空间中安装有沿前后方向延伸的旋转轴和被配置为向该旋转轴提供驱动力的马达；第一叶轮,所述第一叶轮联接到所述旋转轴的一端,该第一叶轮被配置为初次压缩引入到所述制冷剂吸入孔中的所述制冷剂；从所述第一叶轮的出口向后延伸的连接通道,所述连接通道被配置为围绕所述马达壳体；以及联接到所述旋转轴的另一端的第二叶轮,该第二叶轮被配置为对通过所述连接通道引入的所述制冷剂进行二次压缩。(A turbo compressor and a turbo cooler including the turbo compressor. The turbo compressor includes: a case configured to define an external appearance, a front portion of the case being provided with a refrigerant suction hole through which refrigerant is introduced; a motor housing configured to define an accommodation space in which a rotation shaft extending in a front-rear direction and a motor configured to provide a driving force to the rotation shaft are installed; a first impeller coupled to one end of the rotary shaft, the first impeller being configured to primarily compress the refrigerant introduced into the refrigerant suction hole; a connection channel extending rearward from an outlet of the first impeller, the connection channel configured to surround the motor housing; and a second impeller coupled to the other end of the rotary shaft, the second impeller being configured to secondarily compress the refrigerant introduced through the connection passage.)

1. A turbocompressor, which comprises:

a case configured to define an external appearance, a front portion of the case being provided with a refrigerant suction hole through which refrigerant is introduced;

a motor housing configured to define an accommodation space in which a rotation shaft extending in a front-rear direction and a motor configured to provide a driving force to the rotation shaft are installed;

a first impeller coupled to one end of the rotary shaft, the first impeller being configured to primarily compress the refrigerant introduced into the refrigerant suction hole;

a connection channel extending rearward from an outlet of the first impeller, the connection channel configured to surround the motor housing; and

a second impeller coupled to the other end of the rotary shaft, the second impeller being configured to secondarily compress the refrigerant introduced through the connection passage.

2. The turbocompressor according to claim 1, wherein the motor housing is arranged spaced inwardly from the outer casing and

the connecting passage is disposed in a spaced-apart space between the outer shell and the motor housing.

3. The turbocompressor according to claim 1, wherein the motor housing is surrounded by the outer shell.

4. The turbocompressor according to claim 1, wherein the connecting passage is provided in a space defined between an inner peripheral surface of the outer shell and an outer peripheral surface of the motor housing.

5. The turbocompressor according to claim 1, wherein the first and second impellers are arranged on a front side and a rear side of the motor, respectively.

6. The turbocompressor according to claim 1, wherein the outlet of the first impeller and the outlet of the second impeller face in the same direction, and

the first impeller and the second impeller are disposed to be spaced apart from each other in the front-rear direction so as to be connected by the connection passage.

7. The turbocompressor according to claim 1, wherein the first impeller is provided as a mixed-flow impeller.

8. The turbocompressor according to claim 7, wherein the second impeller is provided as a centrifugal impeller and has a diameter range equal to that of the first impeller.

9. The turbocompressor according to claim 1, further comprising vanes mounted in said connecting channel to direct the flow of said refrigerant.

10. The turbocompressor according to claim 9, wherein the vanes extend from the outer circumferential surface of the motor housing to the inner circumferential surface of the casing.

11. The turbocompressor according to claim 10, wherein the vanes comprise a first vane and a second vane disposed behind the first vane, and

each of the first blade and the second blade has an airfoil shape in the front-rear direction.

12. The turbocompressor according to claim 11, wherein the second vane is provided as a plurality of second vanes which are arranged spaced apart from each other in both circumferential directions with respect to the trailing edge of the first vane.

13. The turbocompressor according to claim 10, wherein the blade includes an electric wire hole through which the accommodation space of the motor housing and the outside of the casing communicate with each other, and

a wire configured to provide power is inserted into the wire hole.

14. The turbocompressor according to claim 1, further comprising a radial bearing and a thrust bearing configured to support rotation of the rotating shaft,

wherein the radial bearing includes a first bearing and a second bearing that are disposed apart from each other in the front-rear direction with respect to a center point of the rotation shaft.

15. The turbocompressor according to claim 14, wherein the thrust bearing is arranged between the first bearing and the first impeller.

16. The turbocompressor of claim 14, wherein the motor comprises a permanent magnet motor, and

the radial bearing includes a magnetic bearing configured to support the rotating shaft with a magnetic force.

17. The turbocompressor according to claim 1, wherein the connecting channel comprises:

a discharge passage configured to guide the refrigerant discharged from the first impeller, the discharge passage extending to have a diameter increasing backward from an outlet of the first impeller;

a connection passage extending rearward from the discharge passage to have a constant diameter; and

an inflow passage extending to have a diameter decreasing rearward from the connection passage, the inflow passage being configured to guide the refrigerant to be introduced into the second impeller.

18. The turbine compressor of claim 1, further comprising a volute coupled to an aft end of the housing and having a refrigerant discharge hole,

wherein the refrigerant passing through the second impeller is introduced into the refrigerant discharge hole.

19. A turbine cooler, the turbine cooler comprising:

a turbocompressor according to any one of claims 1 to 18;

a condenser configured to heat-exchange refrigerant compressed in the turbo compressor with cooling water;

an expansion valve that expands the refrigerant passing through the condenser; and

an evaporator configured to evaporate the refrigerant passing through the expansion valve to provide expanded refrigerant to the turbo compressor.

20. The turbine cooler of claim 19, further comprising:

an economizer installed between the expansion valve and the evaporator; and

an injection pipe through which the refrigerant separated from the economizer flows,

wherein the turbo compressor includes:

an injection tube connection passage configured to communicate with the injection tube; and

an injection hole defined in the housing such that the injection tube connection channel and the connection channel communicate with each other.

Technical Field

The invention relates to a turbo compressor and a turbo cooler including the turbo compressor.

Background

Typically, the turbo-cooler may comprise a refrigeration cycle. That is, the turbo cooler may include: a turbo compressor that sucks a low-pressure refrigerant to compress the low-pressure refrigerant into a high-pressure refrigerant; a condenser in which the compressed refrigerant is condensed; an expansion device which expands the refrigerant passing through the condenser; and an evaporator that evaporates the refrigerant expanded in the expansion device.

The turbocompressor may comprise a centrifugal compressor. In addition, the turbo compressor may be used to discharge gas in a high pressure state while converting kinetic energy generated by the driving motor into positive pressure.

In detail, the turbo compressor may include an impeller rotated by a driving force of a driving motor to compress refrigerant, a diffuser, and a casing in which the impeller is received.

Here, the impeller may be provided with a plurality of impellers. For example, the impeller may be provided as a two-stage centrifugal impeller. Since the two-stage centrifugal impeller performs centrifugal compression in two stages, compression efficiency can be improved as compared with the case of performing centrifugal compression in one stage.

The impeller may be classified into a centrifugal impeller, a mixed-flow impeller, and an axial-flow impeller. Here, the impeller has a relationship that a specific speed range is limited according to the shape and a specific diameter increases as the specific speed decreases.

Specifically, the centrifugal impeller has a relatively minimum number of revolutions and a maximum impeller size, and the axial-flow impeller has a relatively maximum number of revolutions and a minimum impeller size. The mixed-flow impeller may have a range between a centrifugal impeller and an axial-flow impeller.

That is, the turbo compressor provided with the two-stage centrifugal impeller according to the related art has a limitation in an increase in size of the impeller because there is a limitation in a range due to an increase in the number of revolutions. In detail, the turbo compressor according to the related art is limited in that since a specific speed design range of the centrifugal impeller must be selected to be about 1.1 or less, the impeller must be increased in size (or diameter).

Further, in the turbo compressor provided with the two-stage centrifugal impeller according to the related art, the outlet of the first impeller performing the first centrifugal compression (one stage) and the outlet of the second impeller performing the second centrifugal compression (two stages) may face the same direction, and the outlet of the first impeller may be provided to be directly connected to the inlet of the second impeller. It will be appreciated that the arrangement of the two stages of centrifugal impellers is a "series arrangement".

When two-stage centrifugal impellers are arranged in series, since each of the first impeller and the second impeller has a circular shape, there is a limitation in size increase of the turbo compressor. Also, since the shape of the passage connecting the first impeller to the second impeller is complicated, there is a limit in that the pressure loss increases.

As another example, in a turbo compressor provided with two-stage centrifugal impellers according to the related art, an outlet of the first impeller and an outlet of the second impeller may be disposed to be spaced apart from each other in both side directions with respect to the drive motor. The arrangement of the two-stage centrifugal impeller may be understood as a "symmetrical arrangement".

When the two-stage centrifugal impeller is symmetrically disposed, there is a limit in that the size of the turbo compressor is further increased because a separate connection pipe for connecting the first impeller to the second impeller is provided. In addition, for the above reason, there is a problem that the compressor is increased in size since each of the first impeller and the second impeller has a circular shape.

The relevant prior art literature information is as follows.

[ Prior art documents ]

[ patent document ]

(patent document 1) KR10-2011-

(patent document 2) US2017/0146271A1, (TURBO CHILLER; TURBO cooler)

(patent document 3) US2017/0336106A1, (TURBO ECONOMIZER USED IN CHILLER SYSTEM; TURBO ECONOMIZER USED in chiller system)

Disclosure of Invention

Embodiments provide a turbo compressor and a turbo cooler including the same.

Embodiments also provide a turbo compressor capable of improving performance while minimizing the size of the turbo compressor, and a turbo cooler including the turbo compressor.

Embodiments also provide a turbo compressor capable of minimizing the size of an impeller while improving compression performance in a multi-stage compression process, and a turbo cooler including the turbo compressor.

Embodiments also provide a turbo compressor capable of reducing a pressure loss of a refrigerant occurring in a multi-stage compression process, and a turbo cooler including the turbo compressor.

Embodiments also provide a turbo compressor capable of minimizing, simplifying, or straightening a refrigerant flow between two impellers performing multi-stage compression, and a turbo cooler including the turbo compressor.

Embodiments also provide a turbo compressor capable of reducing a loss occurring in a refrigerant flow between an impeller performing an initial compression and an impeller performing a next compression, and a turbo cooler including the turbo compressor.

In one embodiment, a turbocompressor comprises: a case configured to define an external appearance, a front portion of the case being provided with a refrigerant suction hole through which refrigerant is introduced; a motor housing configured to define an accommodation space in which a rotation shaft extending in a front-rear direction and a motor configured to provide a driving force to the rotation shaft are installed; a first impeller coupled to one end of the rotary shaft, the first impeller being configured to primarily compress the refrigerant introduced into the refrigerant suction hole; a connection channel extending rearward from an outlet of the first impeller, the connection channel configured to surround the motor housing; and a second impeller coupled to the other end of the rotary shaft, the second impeller being configured to secondarily compress the refrigerant introduced through the connection passage.

The motor housing may be arranged to be spaced inwardly from the outer shell, and the connection passage may be provided in a spaced space between the outer shell and the motor housing

The motor housing may be surrounded by the outer shell.

The connection passage may be provided in a space defined between an inner circumferential surface of the housing and an outer circumferential surface of the motor housing.

The first impeller and the second impeller may be disposed at a front side and a rear side of the motor, respectively.

The outlet of the first impeller and the outlet of the second impeller may face in the same direction, and the first impeller and the second impeller may be disposed to be spaced apart from each other in the front-rear direction so as to be connected by the connection passage.

The first impeller may be provided as a mixed flow impeller.

The second impeller may be provided as a centrifugal impeller, and a diameter range of the second impeller is equal to a diameter range of the first impeller.

The turbo compressor may further include a vane installed in the connection passage to guide a flow of the refrigerant.

The blades may extend from an outer circumferential surface of the motor housing to an inner circumferential surface of the housing.

The blades may include a first blade and a second blade disposed behind the first blade.

Each of the first blade and the second blade may have an airfoil shape in the front-rear direction.

The second blade may be provided as a plurality of second blades that are provided to be spaced apart from each other in both circumferential directions with respect to a trailing edge of the first blade.

The blade may include a wire hole through which the receiving space of the motor housing and the outside of the outer case communicate with each other.

A wire configured to provide power is inserted into the wire hole.

The turbo compressor may further include a radial bearing and a thrust bearing configured to support rotation of the rotary shaft.

The radial bearing may include a first bearing and a second bearing that are disposed apart from each other in the front-rear direction with respect to a center point of the rotation shaft.

The thrust bearing may be disposed between the first bearing and the first impeller.

The motor may include a permanent magnet motor, and the radial bearing may include a magnetic bearing configured to support the rotating shaft with a magnetic force.

The connection path may include: a discharge passage configured to guide the refrigerant discharged from the first impeller, the discharge passage extending to have a diameter increasing backward from an outlet of the first impeller; a connection passage extending rearward from the discharge passage to have a constant diameter; and an inflow passage extending to have a diameter reduced backward from the connection passage, the inflow passage being configured to guide the refrigerant to be introduced into the second impeller.

The turbo compressor may further include a volute coupled to the rear end of the casing and having a refrigerant discharge hole, wherein the refrigerant passing through the second impeller may be introduced into the refrigerant discharge hole.

In another embodiment, a turbine cooler comprises: a turbo compressor; a condenser configured to heat-exchange refrigerant compressed in the turbo compressor with cooling water; an expansion valve that expands the refrigerant passing through the condenser; and an evaporator configured to evaporate the refrigerant passing through the expansion valve to provide expanded refrigerant to the turbo compressor.

The turbine cooler may further include: an economizer installed between the expansion valve and the evaporator; and an injection pipe through which the refrigerant separated from the economizer flows.

The turbo compressor may include: an injection tube connection passage configured to communicate with the injection tube; and an injection hole defined in the housing such that the injection tube connection channel and the connection channel communicate with each other.

The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

Drawings

Fig. 1 is a schematic diagram illustrating the configuration of a turbo cooler and the flow of refrigerant according to an embodiment.

Fig. 2 is a sectional view of a configuration of a turbo compressor according to an embodiment.

Fig. 3 is a schematic view illustrating a flow of refrigerant in a connection passage of a turbo compressor according to an embodiment.

Fig. 4 is a sectional view taken along line a-a' in fig. 3.

Fig. 5 is a graph illustrating a result obtained by measuring a refrigerant swirl angle depending on a distance from a turbo compressor to a connection passage according to an embodiment.

Detailed Description

Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; on the contrary, alternative embodiments included in other degenerative inventions or within the spirit and scope of the present disclosure will fully convey the concept of the invention to those skilled in the art.

Fig. 1 is a schematic diagram illustrating the configuration of a turbo cooler and the flow of refrigerant according to an embodiment.

Referring to fig. 1, a turbo cooler 10 according to an embodiment may include a turbo compressor 100 (hereinafter, referred to as a "compressor") compressing a refrigerant, a condenser 20 condensing the refrigerant compressed in the compressor 100, expansion valves 30 and 50 decompressing the refrigerant condensed in the condenser 20, and an evaporator 60 evaporating the refrigerant decompressed in the expansion valves 30 and 50.

Further, the turbo cooler 10 may further include an economizer 40 that separates liquid refrigerant and gas refrigerant from the refrigerant decompressed by the expansion valves 30 and 50.

In order to improve the refrigerant compression efficiency in two stages, the gas refrigerant separated in the economizer 40 may be introduced into the compressor 100 through the injection pipe 45.

In detail, the injection pipe 45 may extend from the economizer 40 to an injection pipe connection passage 210 (see fig. 2) provided at one side of the compressor 100. The refrigerant introduced into the injection pipe connection passage 210 may be discharged through a connection passage 320 (see fig. 2) provided in the compressor 100. The refrigerant discharged from the injection pipe-connecting passage 210 may be mixed with the primarily (or primarily) compressed refrigerant.

The expansion valves 30 and 50 may include a first expansion valve 30 and a second expansion valve 50, the first expansion valve 30 primarily decompressing the refrigerant condensed in the condenser 20, and the second expansion valve 50 secondarily decompressing the liquid refrigerant separated in the economizer 40.

The first expansion valve 30 or the second expansion valve 50 may include an Electronic Expansion Valve (EEV) capable of adjusting an opening degree.

The compressor 100 may comprise a centrifugal turbo compressor.

A suction pipe 12 guiding suction of refrigerant evaporated in the evaporator 60 may be installed at an inlet side of the compressor 100. Also, a discharge pipe 14 extending to the condenser 20 may be installed at an outlet side of the compressor 100.

The cooling water W1 is introduced into the condenser 20 and discharged from the condenser 20, and the cooling water is heated by heat exchange with the refrigerant while passing through the condenser 20.

Also, the cooling water W2 is introduced into the evaporator 60 and discharged from the evaporator 60, and the cooling water is cooled by heat exchange with the refrigerant while passing through the evaporator 60.

The compressor 100 includes: a motor 110 that generates a driving force; a power transmission member 115 that transmits the driving force of the motor 110 to the impellers 141 and 143; and a rotary shaft 120 connecting the power transmission member 115 to the impellers 141 and 143.

The motor 110 may include a Permanent Magnet (PM) motor for high-speed rotation.

The impellers 141 and 143 may include a first impeller 141 primarily compressing the refrigerant introduced into the refrigerant suction hole 202 and a second impeller 143 secondarily compressing the primarily compressed refrigerant.

The first and second impellers 141 and 143 may be disposed in two directions with respect to the motor 110, respectively. That is, the first and second impellers 141 and 143 may be disposed to be spaced apart from each other in the front-rear direction with respect to the motor 110.

For example, the first impeller 141 may be disposed at a front side (or an inlet side) of the compressor 100, and the second impeller 143 may be disposed at a rear side (or an outlet side) of the compressor 100.

The refrigerant passing through the second impeller 143 may be discharged to the refrigerant discharge hole 104 (see fig. 2) and then introduced into the discharge pipe 14.

The first impeller 141 and the second impeller 143 may be rotated together due to the rotation of the rotation shaft 120.

The compressor 100 may be provided with a refrigerant suction hole 202 (see fig. 2) communicating with the suction pipe 12. The refrigerant suction hole 202 may be connected to an outlet side of the suction pipe 12.

Further, the turbo cooler 10 may further include a liquid droplet supply pipe 70 that supplies the refrigerant condensed in the condenser 20 to the compressor 100.

The refrigerant supplied through the droplet-supplying pipe 70 may be in a condensed state and thus may have a liquid phase. Also, the pressure of the droplet refrigerant supplied through the droplet supply pipe 70 may be greater than the pressure of the primarily compressed refrigerant flowing through the later-described connection passage 320.

Fig. 2 is a sectional view of a configuration of a turbo compressor according to an embodiment.

Referring to fig. 2, the compressor 100 may further include a casing 200 provided with a refrigerant suction hole 202.

The housing 200 may define an external appearance of the compressor 100. For example, the housing 200 may have a hollow shape, the inside of which is hollow. The housing 200 may have a generally cylindrical shape.

The housing 200 may be provided with a plurality of housing parts 200a, 200b, and 200c connected to each other to seal the inner space.

The plurality of housing portions 200a, 200b, and 200c may be coupled to one another to define an integrated appearance. Therefore, since the casing 200 is provided to be assembled, the compressor 100 can be easily assembled and disassembled.

In detail, the housing 200 may include a first housing part 200a disposed at a front side, a second housing part 200b disposed behind the first housing part 200a, and a third housing part 200c disposed behind the second housing part 200 b.

The first housing portion 200a and the third housing portion 200c may be connected to each other by the second housing portion 200 b. For example, second housing section 200b may be connected to the rear end of first housing section 220a and the front end of third housing section 220 c.

The first housing portion 200a may provide an injection pipe connection passage 210 into which the refrigerant separated from the economizer 40 is introduced into the injection pipe connection passage 210. As described above, the injection pipe connection passage 210 is connected to the injection pipe 45.

The inlet pipe connection passage 210 may be provided as a hollow portion extending in the circumferential direction in the first housing portion 200 a. For example, the filler pipe connection passage 210 may be understood as a space defined in the circumferential direction between an inner circumferential surface of the first housing portion 200a, which faces an outer circumferential surface of the motor housing 114 described later, and an outer circumferential surface of the first housing portion 200 a.

The injection hole 220 may be defined in an outer circumferential surface of the motor housing 114, and the refrigerant flowing through the injection pipe connection channel 210 is introduced into a connection channel, which will be described later.

For example, the injection hole 220 may be perforated to allow the injection pipe connection channel 210 and a discharge passage 310, which will be described later, to communicate with each other. Accordingly, the refrigerant flowing through the injection pipe-connecting passage 210 may be mixed with the refrigerant discharged from the first impeller 141 through the injection hole 220.

A refrigerant suction hole 202 may be defined in a front surface of the first housing portion 200a, and the refrigerant suction hole 202 may extend rearward from the interior of the first housing portion 200 a. That is, the refrigerant suction hole 202 may be opened in the front-rear direction and connected to the suction pipe 12 at the front end. In other words, the refrigerant suction hole 202 may be defined in the inlet (or front) of the casing 200.

The first impeller 141 may be disposed within the first housing portion 200 a. That is, the first impeller 141 may be disposed in a refrigerant passage extending from the refrigerant suction hole 202.

The refrigerant sucked into the refrigerant suction hole 202 may be primarily compressed while passing through the first impeller 141.

The second impeller 143 may be disposed within the third housing portion 200 c.

The volute 103 may be coupled to the rear end of the third housing portion 200 c. In this case, the scroll 103 may be provided in the refrigerant discharge hole 104.

Also, the scroll 103 may guide the refrigerant discharged from the second impeller 143 in the radial direction to the refrigerant discharge hole 104. That is, the inner space of the scroll case 103 may extend to connect the outlet of the second impeller 143 to the refrigerant discharge hole 104.

The compressor 100 may also include a motor housing 114 surrounded by a shell 200.

The motor housing 114 may be spaced inwardly from the housing 200. That is, a space having a predetermined gap may be defined between the motor housing 114 and the outer case 200.

A motor housing 114 may be disposed around the motor 110. For example, the motor housing 114 may have a substantially cylindrical shape having the receiving space 113. The motor 110 may be installed in the receiving space 113 of the motor housing 114.

Also, the motor housing 114 may be configured to be assembled or disassembled corresponding to the housing 200. For example, the motor housing 114 may be provided with a plurality of housing parts 114a, 114b, and 114c, and the housing parts 114a, 114b, and 114c are coupled to each other to seal the accommodating space 113.

In detail, the motor housing 114 may include: a first housing portion 114a provided to correspond to the interior of the first housing portion 200 a; a second housing portion 114b coupled to a rear end of the first housing portion 114a and disposed to correspond to an interior of the second housing portion 200b, and a third housing portion 114c coupled to a rear end of the second housing portion 114b and disposed to correspond to an interior of the third housing portion 200 c.

A rotation shaft 120 extending in the front-rear direction may be disposed in the accommodation space 113 of the motor housing 114.

The rotation shaft 120 may be disposed at the center of the motor housing 114. That is, the rotary shaft 120 may be understood as a central axis of the compressor 100.

The rotation shaft 120 may be rotated by a driving force of the motor 110.

The first impeller 141 may be coupled to one end of the rotary shaft 120, and the second impeller 143 may be coupled to the other end of the rotary shaft 120.

For example, the front end of the rotating shaft 120 may be coupled to the first impeller 141. Also, the rear end of the rotation shaft 120 may be coupled to the second impeller 143.

Accordingly, the first and second impellers 141 and 143 may be rotated according to the rotation of the rotation shaft 120.

The motor 110 may include a rotor 111 and a stator 112 providing a driving force. Here, the rotor 111 and the stator 112 may be provided in a pair.

The stator 112 may be connected to the inside of the motor housing 114. For example, the stator 112 may be connected along an inner circumferential surface of the second housing portion 114 b. Also, the stator 112 may extend in a circumferential direction with respect to the rotational shaft 120.

The rotor 111 may be disposed inside the stator 112 to extend in a circumferential direction so as to surround a central portion of the rotation shaft 120. For example, the rotor 111 may be connected to a central portion of the rotation shaft 120.

Alternatively, the power transmission member 115 may further include one or more gears coupled with the motor 110 to allow the rotation shaft 120 to rotate.

Further, the power transmission member 115 may further include radial bearings 121 and 122 and a thrust bearing 125 supporting the rotation of the rotation shaft 120.

Since the first and second impellers 141 and 143 are connected to the front and rear ends of the rotary shaft 120, respectively, the radial bearings 121 and 122 may include a first bearing disposed near the first impeller 141 and a second bearing 122 disposed near the second impeller 143 with respect to the center or central point of the rotary shaft 120.

That is, the first bearing 121 and the second bearing 122 may be disposed to be spaced apart from each other in the front-rear direction or in both directions from the center point of the rotation shaft 120.

Since the first bearing 121 and the second bearing 122 are coupled to surround the rotation shaft 120, the position of the rotation shaft 120 may be fixed, and friction due to rotation may also be reduced.

Each of the first bearing 121 and the second bearing 122 may include a magnetic bearing that supports the rotation shaft 120 using magnetic force.

The thrust bearing 125 may be disposed between the first bearing 121 and the first impeller 141. The thrust bearing 125 may support a load acting in the axial direction of the rotary shaft 120.

The compressor 100 may further include a connection passage 300 that guides the primarily compressed refrigerant passing through the first impeller 141 to the second impeller 143.

The connecting channel 300 may be provided by the housing 200 and the motor housing 114. That is, the connection passage 300 may be provided as a space between the inner circumferential surface of the housing 200 and the outer circumferential surface of the motor housing 114.

In other words, the shell 200 and the motor housing 114 may provide a passage for refrigerant to flow from the refrigerant suction hole 202 (which is defined at the front of the compressor 100) to the refrigerant discharge hole (which is defined at the rear of the compressor 100).

In other words, the connection passage 300 is provided inside the compressor 100 to surround the motor housing 114.

In detail, the connection channel 300 may include: a discharge passage 310 guiding the refrigerant discharged from the first impeller 141; a connection passage 320 extending rearward from the discharge passage 310; and an inflow path 330 extending rearward from the connection path 320 to guide the refrigerant such that the refrigerant is introduced into the second impeller 143.

For example, the discharge passage 310 may have a diameter increasing rearward from the outlet of the first impeller 141. Also, the connection passage 320 may extend toward the rear side with a constant diameter. Further, the diameter of the inflow path 330 may decrease toward the rear side where the inlet of the second impeller 143 is provided.

Accordingly, since the primarily compressed refrigerant discharged from the first impeller 141 is introduced into the second impeller 143 along the connection passage 300 provided in a relatively streamlined shape, a flow loss of the refrigerant may be reduced.

The discharge passage 310 may be provided as a space defined by an outer circumferential surface of the first housing portion 114a and an inner circumferential surface of the first housing portion 200 a. In other words, the drain passage 310 may be disposed circumferentially around the first housing portion 114 a.

The injection hole 220 may extend to the discharge passage 310 to allow the refrigerant injected into the pipe connection channel 210 to be introduced into the discharge passage 310.

The connection passage 320 may be provided as a space defined by an outer circumferential surface of the second housing portion 114b and an inner circumferential surface of the second housing portion 200 b. In other words, the connection passage 320 may be disposed circumferentially around the second housing portion 114 b.

The connection passage 320 may guide the refrigerant flowing through the discharge passage 310 to flow into the inflow passage 330. For example, later-described blades 410 and 420 may be installed in the connection passage 320. As a result, the swirl of the refrigerant passing through the connection passage 320 can be reduced.

The inflow passage 330 may be provided as a space defined by an outer circumferential surface of the third housing portion 114c and an inner circumferential surface of the third housing portion 200 c. In other words, the inflow passage 330 may be disposed circumferentially around the third housing portion 114 c.

The inflow passage 330 may guide the refrigerant flowing through the connection passage 320 to an inlet of the second impeller 143.

As a result, the primarily compressed refrigerant compressed in the first impeller 141 may flow along the connection passage 300 to flow into the second impeller 143. In addition, the secondarily compressed refrigerant additionally compressed in the second impeller 143 may be introduced into the discharge pipe 14 through the refrigerant discharge hole 104 to flow into the condenser 20.

The impellers 141 and 143 according to one embodiment may be arranged in series, as opposed to the series-sequential arrangement or symmetrical arrangement described above.

That is, the outlet of the first impeller 141 may be connected to the connection channel 300, which is provided around the outer circumference of the motor 110 or along the outer circumferential surface of the motor housing 114, and the connection channel 300 may be connected to the inlet of the second impeller 143.

As a result, the direction in which the outlet of the first impeller 141 and the inlet of the second impeller 143 point may be the same, but the first impeller 141 and the second impeller 143 may be spaced apart from each other.

Also, the first impeller 141 may be provided as a mixed flow impeller. For example, the first impeller 141 may be provided as a mixed flow impeller, and the second impeller 143 may be provided as a centrifugal impeller.

As described above, when the first impeller 141 is provided as a mixed-flow impeller, the rotational speed can be increased and the diameter (or size) can be reduced as compared with the conventional centrifugal impeller.

For example, the first impeller 141 may have a diameter range of about 300mm to about 400 mm. Here, the diameter of the second impeller 143 provided as a centrifugal impeller may range from about 300mm to about 400 mm. That is, according to an embodiment, the diameter of the first impeller 141 provided as a mixed flow impeller and the diameter of the impeller 143 provided as a centrifugal impeller may be designed within the same range while satisfying the target performance of the compressor 100. Therefore, the overall diameter of the compressor 100 can be reduced as compared with the case where the first impeller is provided as a centrifugal impeller.

As a result, since the number of revolutions of the first impeller 141 is higher than that of the centrifugal impeller, the compression performance can be improved. Therefore, it is possible to better suit the characteristics of the recently proposed eco-friendly refrigerant (e.g., R1233zd) than the refrigerant such as the existing R-134 a.

In addition, even if the first impeller 141 is provided as a mixed flow impeller, the flow of the refrigerant introduced into the second impeller 143 through the connection passage 300 may be relatively straightened. Therefore, the flow loss of the refrigerant can be reduced.

In addition, the diameter of the first impeller 141 may be further reduced, and the compressor 100 may be more compact by the connection passage 300 surrounding the motor housing 114.

Further, since the connection passage 300 surrounds the motor housing 114, dew condensation caused by a temperature difference between the existing motor housing and the outside air can be prevented.

The compressor 100 may further include a diffuser (not shown) mounted on a rear surface of the second impeller 143 to compress the refrigerant discharged from the second impeller 143 in a radial direction.

For example, the diffuser may be coupled to an end of the rotating shaft 120 and installed at a central portion of the rear surface of the second impeller 143.

The diffuser may include diffuser vanes (not shown) protruding forward toward the second impeller 143 and disposed in plurality in the circumferential direction.

For example, the diffuser vanes may extend in a rake shape along the radial direction. Also, the diffuser vane may compress and guide the refrigerant passing through the second impeller 143.

Fig. 3 is a schematic view illustrating a flow of refrigerant in a connection passage of a turbo compressor according to an embodiment, and fig. 4 is a sectional view taken along line a-a' of fig. 3.

Referring to fig. 2 to 4, the compressor 100 may further include blades 410 and 420 provided in the connection passage 300.

The vanes 410 and 420 may guide the flow of the refrigerant such that the swirl of the refrigerant passing through the connection passage 300 is reduced and the flow direction of the refrigerant is more straight.

That is, when the first impeller 141 is provided as a mixed flow impeller, the refrigerant discharged from the first impeller 141 and introduced into the connection passage 300 may have a strong rotational component. Accordingly, the vanes 410 and 420 may perform functions of reducing a loss of the refrigerant flowing through the connection passage 300 and reducing a rotational flow component to allow the refrigerant to be more efficiently introduced into the second impeller 143.

The blades 410 and 420 may extend from the outer circumferential surface of the motor housing 114 to the inner circumferential surface of the casing 200. In other words, the blades 410 and 420 may extend to connect a surface of the connection channel 300 having a larger radius with respect to the rotation axis 120 to a surface of the connection channel 300 having a smaller radius with respect to the rotation axis 120.

For example, the plurality of blades 410 and 420 may be provided in plurality along the circumference of the motor housing 114, and each blade 410 and 420 may extend in a radial direction (upward and downward directions in fig. 2). That is, the blades 410 and 420 may extend in a radial direction with respect to the rotational shaft 120 to provide a wall in a partial space of the connection passage 300.

That is, the refrigerant passing through the connection passage 300 may be guided by the blades 410 and 420 connecting the inner circumferential surface of the casing 200 to the outer circumferential surface of the motor housing 114.

As a result, the flow direction of the refrigerant passing through the connection passage 300 may be directed in the forward and backward extending directions of the blades 410 and 420.

The motor 110 and a plurality of electronic devices may be installed in the receiving space 113 of the motor housing 114. However, according to one embodiment, since the connection passage 300 is provided to surround the motor housing 114, it is difficult to introduce the electric wire supplying power to the motor 110 and the like into the accommodation space 113 of the motor housing 114.

To solve this limitation, the blades 410 and 420 may include wire holes 411 and 412, which connect the receiving space 113 of the motor housing 114 to the external space of the casing 200.

Each of the wire holes 411 and 412 may be provided by allowing a hole having a predetermined diameter to extend in an extending direction, i.e., in a radial direction of the blades 410 and 420.

Also, the wire holes 411 and 412 may allow the outside of the case 200 to communicate with the receiving space 113. Accordingly, power can be supplied to the components disposed in the accommodating space 113.

The blades 410 and 420 may include a first blade 410 and a second blade 420 disposed behind the first blade 410.

The first blade 410 and the second blade 420 may extend in an airfoil shape in the front-rear direction.

Also, the refrigerant F passing through the connection passage 300 may be first guided along a curved surface extending in the front-rear direction after colliding with the most leading edge of the first vane 410. The leading edge may be referred to herein as the "leading edge".

The second blade 420 may be provided in plural spaced apart from each other in both circumferential directions with respect to the center of the most trailing edge of the first blade 410. The last edge may be referred to herein as the "trailing edge".

Accordingly, the refrigerant F flowing along the curved surface of the first vane 410 may exit the trailing edge of the first vane 410 to collide with the leading edge of the second vane 420. Also, the refrigerant F colliding with the second vane 420 may be guided rearward along a curved surface extending in the front-rear direction of the second vane 420. Accordingly, the refrigerant F passing through the connection passage 300 may reduce a component causing a vortex flow while sequentially passing through the first and second vanes 410 and 420, and may relatively increase a direct current component.

The first blade 410 and the second blade 420 may be provided to be disposed in the connection passage 320. Since the discharge passage 310 and/or the inflow passage 330 have an inclination on a horizontal line (or an extension line of the rotation axis) along the first and third housing portions 114a and 114c, the flow component of the refrigerant connecting the passage 320 can be more easily controlled.

The first blade 410 and a plurality of second blades 420 spaced from each other in a circumferential direction with respect to a trailing edge of the first blade 410 may be defined in groups. Also, the blades 410 and 420 provided in one set may be provided in plurality in the circumferential direction on the outer circumferential surface of the motor housing 114.

A plurality of wire holes 411 and 412 may be provided. For example, the wire holes 411 and 412 may include a first wire hole 411 and a second wire hole 412 having diameters different from each other.

The first wire hole 411 may have a diameter greater than that of the second wire hole 412 so that a plurality of wires are inserted into the receiving space 113.

Also, the second wire hole 412 may be disposed to be spaced apart from the first wire hole 411. Accordingly, the user can select the wire holes 411 and 412 near the components mounted in the receiving space 113 to insert the wires.

For example, a wire for supplying power to the motor 110 may be inserted into the first wire hole 411, and a wire for supplying power to the sensors mounted in the plurality of bearings 121, 122, and 125 may be inserted into the second wire hole 412.

Wire holes 411 and 312 may pass through a first blade 410 having a greater width or surface area than a second blade 420. Of course, the wire holes 411 and 412 may also be defined in the second blade 420.

Fig. 5 is a graph illustrating a result obtained by measuring a swirl angle of refrigerant depending on a distance from a turbo compressor to a connection passage according to an embodiment.

In detail, fig. 5 shows an experimental graph comparing a case (solid line) where the blades 410 and 420 according to one embodiment are installed in the connection passage 300 with a case (dotted line) where the blades are not installed.

In the experiment of fig. 5, the length of the connection passage 300 (i.e., the distance between the outlet of the first impeller 141 and the inlet of the second impeller 143) was about 2m, and the optimal target swirl angle at the inlet of the second impeller 143 was about 90 degrees.

Referring to fig. 5, it can be confirmed that, when the vanes 410 and 420 are installed, the swirl angle of the refrigerant passing through the connection passage 300 is maintained in a state closer to about 90 degrees than when the vanes 410 and 420 are not installed, and thus the refrigerant is introduced into the second impeller 143.

That is, since the refrigerant introduced into the second impeller 143 is introduced through the vanes 410 and 420 at an optimum swirl angle, the efficiency of the secondary compression can be further improved.

Hereinafter, an operation of the compressor 100 according to an embodiment will be schematically described.

First, the rotation shaft 120 may receive a driving force of a motor composed of the stator 112 and the rotor 111 to rotate.

When the rotary shaft 120 rotates, primary compression of the refrigerant sucked into the refrigerant suction hole 202 may be performed by the mixed flow type first impeller 141 connected to the front end of the rotary shaft 120. Here, since the first impeller 141 is provided as a mixed flow impeller, the number of revolutions can be increased and the diameter can be reduced compared to the conventional centrifugal impeller.

The primarily compressed refrigerant may pass through the connection passage 300 disposed to surround the motor housing 114 and disposed to be a streamlined refrigerant passage toward the rear side, and then be finally introduced into the centrifugal second impeller 143.

The second impeller 143 may perform secondary compression of the refrigerant and then discharge the refrigerant into the scroll 103. In addition, the compressed refrigerant may be introduced into the condenser 20 through a refrigerant discharge hole 104 defined in the scroll 103.

Therefore, as compared with the case where all of the first and second impellers are provided as centrifugal impellers arranged in series or symmetrically to each other, the shape of the passage between the two impellers can be simplified, and a pipe for providing a separate passage can be unnecessary to reduce the size of the compressor 100.

In addition, since the vanes 410 and 420 capable of controlling the flow component of the refrigerant are installed in the connection passage 300, it is possible to minimize the swirl of the one-stage compressed refrigerant (gas) at the inlet of the second impeller 143. That is, the refrigerant may be introduced into the second impeller 143 at an optimum angle to reduce flow loss and improve compression efficiency.

According to this embodiment, an impeller that performs initial compression (one-stage compression) may be provided as a mixed-flow impeller to reduce the size of the impeller while maintaining compression performance. That is, the turbo compressor may be compact.

According to this embodiment, since the specific rotation speed of the mixed-flow impeller that performs one-stage compression is increased as compared with the centrifugal impeller according to the related art, the number of revolutions of the impeller is increased and the diameter is reduced.

According to this embodiment, since the mixed-flow impeller that performs one-stage compression is provided, the pressure loss or the flow loss of the refrigerant can be reduced due to the flow direction of the refrigerant discharged from the mixed-flow impeller, as compared with a turbo compressor including two centrifugal impellers in which the refrigerant is discharged in the radial direction and introduced in the axial direction.

According to this embodiment, because the flow space ("connecting passage") of the refrigerant reaching upward to the impeller performing the secondary compression (two-stage compression) is defined around the outer circumferential surface of the motor due to the direction of the refrigerant discharged from the mixed-flow impeller, the pressure loss and the flow loss of the refrigerant occurring during the multi-stage compression in the turbo compressor according to the related art can be reduced, and the size of the turbo compressor can be minimized.

According to this embodiment, an economizer may be provided to improve the efficiency of multi-stage compression, and gas discharged from the economizer may be supplied to an outlet of the mixed-flow impeller, through which one-stage compressed refrigerant is discharged, to reduce flow loss and improve the efficiency of the turbo cooler.

According to this embodiment, two impellers spaced apart from each other with respect to the motor are arranged (arranged in series to be spaced apart from each other) such that outlets through which refrigerant is discharged are directed in the same direction, and a connection passage connecting the two impellers to each other may guide the refrigerant in a relatively straight direction to reduce flow loss.

According to this embodiment, since the vane guiding the flow direction of the refrigerant is provided in the connection passage connecting the two impellers to each other, the refrigerant compressed at one stage can reduce the flow vortex when passing through the connection passage. Accordingly, the refrigerant in which the swirl is minimized may be introduced into an inlet of the impeller for performing the secondary compression, thereby improving the compression efficiency.

According to this embodiment, the mixed-flow impeller for one-stage compression may be configured to increase the rotational speed, and the diameter of the impeller may be increased by about 12% to about 19% as compared to the existing centrifugal impeller.

According to this embodiment, the loss of refrigerant through the connecting passage can be reduced by about 1/3 levels compared to the series continuous arrangement or the symmetrical arrangement according to the prior art.

According to this embodiment, since the connection passage is provided along the outer circumferential surface of the motor, it is possible to prevent a phenomenon in which dew is formed in the motor case (or the motor housing) when the motor is cooled according to the related art.

According to this embodiment, the specific speed range can be increased by about 1.8 times, and the diameter can be reduced by the mixed flow impeller for one-stage compression.

According to this embodiment, the number of parts can be reduced, and the manufacturing cost of the product can be reduced. That is, the economy of the product can be improved.

According to the embodiment, a surge phenomenon occurring in the multistage impeller can be prevented to improve the operational reliability of the turbo cooler.

According to this embodiment, since the structure of the passage connecting the two impellers to each other is relatively simple and straight, the pressure loss of the refrigerant can be minimized.

According to this embodiment, the inflow angle of the refrigerant can be optimized by the vane of the connection passage at the impeller inlet for the secondary compression. As a result, flow loss of the refrigerant can be minimized.

According to the embodiment, since the structure of the turbo compressor is simplified, the turbo compressor can be easily managed and the risk of malfunction is reduced.

Although a number of illustrative embodiments have been described, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.