Patent Publication Number: US-11639724-B2

Title: Turbo compressor having separate cooling air channel

Description:
TECHNICAL FIELD 
     The present invention relates to a turbo compressor and, more particularly, to a turbo compressor capable of efficiently cooling a motor without pressure loss of a compression unit. 
     BACKGROUND ART 
     Turbo compressors or turbo blowers are centrifugal pumps for sucking in external air or a gas, compressing the air or gas, and then providing the compressed air or gas to outside by rotating an impeller at a high speed, and are commonly used to pneumatically convey powder or for aeration at sewage treatment plants, etc. and are also currently used for industrial processes and for vehicles. 
     In the turbo compressors, generation of high heat is unavoidable because of friction between a motor and bearings due to high-speed rotation of the impeller. Major heat sources such as the motor and the bearings need to be cooled. 
     An example of general turbo compressors is disclosed in Korean Patent Publication No. 10-2015-0007755. In this general turbo compressor, a part of air compressed by an impeller is used to cool a motor and bearings for rotating the impeller, and then is supplied again to the impeller through a hole in a rotary shaft of the motor. 
     Although the configuration of a cooling system may be simplified, the general turbo compressor uses a part of the air compressed by the impeller, as a cooling gas and thus pressure loss occurs in the air compressed by the impeller. 
     Furthermore, in the general turbo compressor, since the cooling gas is heated by the motor and the bearings and then is supplied again to the impeller, the temperature of the air to be compressed by the impeller is increased and thus compression efficiency of the turbo compressor is additionally reduced. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     The present invention provides a turbo compressor capable of efficiently cooling a motor without pressure loss of a compression unit. 
     Technical Solution 
     According to an aspect of the present invention, there is provided a turbo compressor for compressing a gas such as air and supplying the compressed gas to outside, the turbo compressor including a compression unit including a compression gas inlet for sucking the gas, an impeller for compressing the gas sucked through the compression gas inlet, a compression gas outlet for discharging the gas compressed by the impeller, and a compression gas channel connected from the compression gas inlet to the compression gas outlet, a motor including a rotary shaft having a front end coupled to the impeller, to rotate the impeller, a housing having a motor accommodation space to accommodate the motor, and a cooling gas channel passing through the motor accommodation space and enabling circulation of a cooling gas contained therein, wherein the compression gas channel is spatially separate from the cooling gas channel and thus the gas in the compression gas channel does not permeate into the cooling gas channel. 
     The cooling gas channel may include gas channels penetrating through the housing to cool the housing. 
     The turbo compressor may further include a cooling fan for circulating the cooling gas contained in the cooling gas channel. 
     The cooling fan may be provided at a rear end of the rotary shaft and is rotated by rotational force of the rotary shaft. 
     The turbo compressor may further include a cooling water channel for enabling circulation of a cooling liquid therein. 
     The cooling water channel may include water channels penetrating through the housing to cool the housing. 
     The cooling water channel may be configured to exchange heat with the cooling gas contained in the cooling gas channel. 
     The cooling gas channel may include gas channels penetrating through the housing to cool the housing, and the gas channels penetrating through the housing and the water channels penetrating through the housing may extend along a length direction of the rotary shaft and be alternately arranged along a circumferential direction of the rotary shaft. 
     Cooling fins capable of increasing heat exchange efficiency may be provided between the cooling water channel and the cooling gas channel. 
     The housing may include an inner housing having the motor accommodation space, and an outer housing surrounding the inner housing, and the cooling gas channel may be provided between an outer surface of the inner housing and an inner surface of the outer housing. 
     Advantageous Effects of the Invention 
     According to the present invention, using a turbo compressor including a compression unit including a compression gas inlet for sucking a gas, an impeller for compressing the gas sucked through the compression gas inlet, a compression gas outlet for discharging the gas compressed by the impeller, and a compression gas channel connected from the compression gas inlet to the compression gas outlet, a motor including a rotary shaft having a front end coupled to the impeller, to rotate the impeller, a housing having a motor accommodation space to accommodate the motor, and a cooling gas channel passing through the motor accommodation space and enabling circulation of a cooling gas contained therein, since the compression gas channel is spatially separate from the cooling gas channel and thus the gas in the compression gas channel does not permeate into the cooling gas channel, the motor may be efficiently cooled without pressure loss of the compression unit. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a cross-sectional view of a turbo compressor according to an embodiment of the present invention. 
         FIG.  2    is a magnified cross-sectional view of a part of the turbo compressor illustrated in  FIG.  1   . 
         FIG.  3    is a cross-sectional view of the turbo compressor cut along line A-A of  FIG.  1   . 
         FIG.  4    is a cross-sectional view of the turbo compressor cut along line B-B of  FIG.  1   . 
         FIG.  5    is a cross-sectional view of the turbo compressor cut along line C-C of  FIG.  1   . 
         FIG.  6    is a cross-sectional view showing a flow path of a cooling liquid of the turbo compressor illustrated in  FIG.  1   . 
         FIG.  7    is a cross-sectional view of a turbo compressor according to a second embodiment of the present invention. 
         FIG.  8    is a cross-sectional view of the turbo compressor cut along line A-A of  FIG.  7   . 
         FIG.  9    is a cross-sectional view of the turbo compressor cut along line B-B of  FIG.  7   . 
         FIG.  10    is a cross-sectional view of the turbo compressor cut along line C-C of  FIG.  7   . 
     
    
    
     BEST MODE 
     Hereinafter, the present invention will be described in detail by explaining embodiments of the invention with reference to the attached drawings. 
       FIG.  1    is a cross-sectional view of a turbo compressor  100  according to an embodiment of the present invention, and  FIG.  2    is a magnified cross-sectional view of a part of the turbo compressor  100  illustrated in  FIG.  1   .  FIG.  3    is a cross-sectional view of the turbo compressor  100  cut along line A-A of  FIG.  1   . 
     Referring to  FIGS.  1  to  3   , the turbo compressor  100  according to an embodiment of the present invention is a centrifugal pump for sucking in an external gas, compressing the gas, and then providing the compressed gas to outside by rotating an impeller at a high speed, and is also called a turbo compressor or a turbo blower. The turbo compressor  100  includes a housing  10 , a compression unit  20 , a motor  30 , an air-cooling unit  40 , and a water-cooling unit  50 . In the following description, the gas to be compressed is assumed as air. 
     The housing  10  is a metal housing and includes an inner housing  11  and an outer housing  12 . 
     The inner housing  11  is a cylindrical member having a motor accommodation space  13  therein, has a circular cross-section around a first central axis C 1 , and extends along the first central axis C 1 . 
     The motor accommodation space  13  is a space having a shape corresponding to the motor  30  to be described below, to accommodate the motor  30 . 
     The inner housing  11  has an open left end and a right end having a cooling fan mounting hole  111 , as illustrated in  FIG.  1   . Herein, the right end of the inner housing  11  includes a few separate components for mounting the motor  30  therein, but a detailed description thereof will not be provided. 
     The outer housing  12  is a cylindrical member having a circular cross-section around the first central axis C 1 , and extends along the first central axis C 1 . 
     The outer housing  12  has a shape corresponding to the inner housing  11 , to surround and accommodate the inner housing  11 . 
     An inner surface of the outer housing  12  and an outer surface of the inner housing  11  are spaced apart from each other by a preset gap to face each other. 
     The compression unit  20  is a device for sucking in external air and compressing the air, and includes an impeller  21 , a front cover  22 , and a rear cover  23 . 
     As a major element of a centrifugal pump, the impeller  21  is a wheel including a plurality of curved blades, and is mounted to be rotatable at a high speed. 
     The front cover  22  is a metal member provided in front of the impeller  21 , and includes a compression gas inlet  24  for sucking the external air. 
     The front cover  22  is provided in the form of a scroll casing having a fluidic channel capable of enabling spiral flow of the air passed through the impeller  21 . 
     The rear cover  23  is a metal member provided behind the impeller  21 , and is coupled to the housing  10  by using bolts or screws. 
     The impeller  21  compresses the air sucked through the compression gas inlet  24 , and the air compressed by the impeller  21  is discharged outside through a compression gas outlet  25 . 
     The air sucked through the compression gas inlet  24  is compressed while moving along a compression gas channel  26  connected from the compression gas inlet  24  to the compression gas outlet  25 . 
     The motor  30  is an electric motor for generating rotational force, and is a device for providing high-speed rotational force to the impeller  21 . The motor  30  includes a rotary shaft  31 , a stator  32 , a rotor  33 , and bearings  34 . 
     The rotary shaft  31  is a rod member extending along the first central axis C 1 , and a front end thereof is relatively non-rotatably coupled to the impeller  21  to rotate the impeller  21 . 
     The stator  32  is a stator wound with a field coil, and is mounted and fixed in the motor accommodation space  13 . 
     The rotor  33  is a rotor including a permanent magnet, and is coupled to a middle part of the rotary shaft  31 . 
     The bearings  34  are air bearings rotatably supporting the rotary shaft  31  to reduce friction generated due to high-speed rotation, and are separately provided at a front end and a rear end of the rotary shaft  31 . 
     A preset gap is provided between the stator  32  and the rotor  33 , between the rotary shaft  31  and the stator  32 , and between the rotary shaft  31  and the bearings  34 . 
     The air-cooling unit  40  is a device for cooling the housing  10  and the motor  30  by using a cooling gas, and includes a cooling gas channel  41  and a cooling fan  42 . Herein, air or an inert gas is used as the cooling gas. 
     The cooling gas channel  41  is a passage containing the cooling gas, and enables continuous circulation of the cooling gas contained therein. 
     The cooling gas channel  41  passes through the motor accommodation space  13  and the housing  10  as illustrated in  FIG.  2   , and includes a rear gas channel  41   a , outer gas channels  41   b , front gas channels  41   c , intermediate gas channels  41   d , and an inner gas channel  41   e.    
     The rear gas channel  41   a  is a gas channel for enabling the cooling gas to flow from the center of a rear end of the inner housing  11  in radial directions of the inner housing  11 . 
     The rear gas channel  41   a  has a disc-shaped space provided between an outer surface of the rear end of the inner housing  11  and an inner surface of a rear end of the outer housing  12 . 
     The outer gas channels  41   b  are gas channels penetrating though the housing  10  to cool the housing  10 , and extend along the first central axis C 1 . 
     The outer gas channels  41   b  are generated by an outer circumferential surface of the inner housing  11 , an inner circumferential surface of the outer housing  12 , and surfaces of cooling fins  52  to be described below, as illustrated in  FIG.  3   . 
     A plurality of outer gas channels  41   b  are arranged along a circumferential direction of the first central axis C 1 , and are connected to the rear gas channel  41   a.    
     The front gas channels  41   c  are gas channels for enabling the cooling gas to flow from the edge toward the center of a front end of the inner housing  11 . 
     The front gas channels  41   c  extend from front ends of the outer gas channels  41   b  to the motor accommodation space  13 , and include a plurality of holes  41   c  penetrating though the inner housing  11 . 
     The intermediate gas channels  41   d  extend from middle parts of the outer gas channels  41   b  to the motor accommodation space  13 , and include a plurality of holes  41   d  penetrating though the inner housing  11 . 
     The inner gas channel  41   e  is a gas channel passing through a space between the rotary shaft  31  and the stator  32 . 
     The inner gas channel  41   e  is connected to the front gas channels  41   c , the rear gas channel  41   a , and the intermediate gas channels  41   d.    
     The inner gas channel  41   e  enables the cooling gas to pass by the field coil of the stator  32 , the rotary shaft  31 , the rotor  33 , and the bearings  34 . 
     The cooling gas channel  41  may be rotationally or axially symmetric with respect to the first central axis C 1 . 
     In the current embodiment, the cooling gas channel  41  is spatially separate from the compression gas channel  26 . Therefore, the air contained in and compressed along the compression gas channel  26  may not leak or permeate into the cooling gas channel  41 . 
     The cooling fan  42  is a cooling fan for forcibly circulating the cooling gas contained in the cooling gas channel  41 , and is mounted in the cooling fan mounting hole  111  of the inner housing  11 . 
     In the current embodiment, the cooling fan  42  is relatively non-rotatably coupled to the rear end of the rotary shaft  31 , and thus rotates together by rotational force of the rotary shaft  31 . 
     The water-cooling unit  50  is a device for cooling the housing  10  by using a cooling liquid, and includes a cooling water channel  51 , the cooling fins  52 , a cooling liquid inlet  53 , and a cooling liquid outlet  54 . Herein, water is used as the cooling liquid. 
     The cooling water channel  51  is a passage containing the cooling liquid, and enables continuously circulation of the cooling liquid contained therein. 
     The cooling water channel  51  penetrates through the inner housing  11  as illustrated in  FIGS.  1  and  3   , and includes unit water channels  51   a , rear water channels  51   b  (see  FIG.  5   ), and front water channels  51   c  (see  FIG.  4   ). 
     The unit water channels  51   a  are circular water channels penetrating through the inner housing  11 , and extend along the first central axis C 1 . 
     A plurality of unit water channels  51   a  are spaced apart from each other and are arranged along the circumferential direction of the first central axis C 1  as illustrated in  FIG.  3   . 
     The rear water channels  51   b  are water channels for interconnecting rear ends of the unit water channels  51   a , and penetrate through the rear end of the inner housing  11  as illustrated in  FIG.  5   . 
     The front water channels  51   c  are water channels for interconnecting front ends of the unit water channels  51   a , and penetrate through the front end of the inner housing  11  as illustrated in  FIG.  4   . 
     Therefore, the cooling water channel  51  is generated in a zigzag shape along a circumferential direction of the inner housing  11  as illustrated in  FIG.  6   , and surrounds the whole side wall of the inner housing  11 . 
     The cooling water channel  51  may be rotationally or axially symmetric with respect to the first central axis C 1 . 
     The cooling fins  52  are cooling fins for increasing heat exchange efficiency between the cooling liquid flowing along the cooling water channel  51  and the cooling gas flowing along the cooling gas channel  41 . 
     The cooling fins  52  protrude from the outer circumferential surface of the inner housing  11  in radial directions of the inner housing  11  as illustrated in  FIGS.  1  and  3   , and extend along the first central axis C 1 . 
     A plurality of cooling fins  52  are spaced apart from each other and are arranged along the circumferential direction of the inner housing  11 . 
     Ends of the cooling fins  52  are in contact with the inner surface of the outer housing  12 . 
     The cooling liquid inlet  53  is an inlet for receiving the cooling liquid from outside, is connected to an end of the cooling water channel  51 , and is provided in the outer housing  12 . 
     The cooling liquid inlet  53  is connected to an external pump (not shown), and thus receives water supplied from the pump. 
     The cooling liquid outlet  54  is an outlet for discharging the cooling liquid to outside, is connected to the other end of the cooling water channel  51 , and is provided in the outer housing  12 . 
     The cooling liquid discharged from the cooling liquid outlet  54  may be cooled outside and then be supplied again through the cooling liquid inlet  53 . 
     An example of an operating method of the above-described turbo compressor  100  will now be described. 
     When the rotary shaft  31  of the motor  30  rotates, the impeller  21  and the cooling fan  42  rotate, and the air sucked through the compression gas inlet  24  is compressed while flowing along the compression gas channel  26  of the compression unit  20  and is discharged through the compression gas outlet  25 . In this case, since the compression gas channel  26  is spatially separate from the cooling gas channel  41 , the air flowing in and compressed along the compression gas channel  26  may not leak or permeate into the cooling gas channel  41 . That is, a flow path of the air flowing along the compression gas channel  26  is not mixed with a flow path G of the cooling gas flowing along the cooling gas channel  41 . 
     The cooling gas contained in the cooling gas channel  41  is forcibly circulated by the cooling fan  42 , and thus passes by the field coil of the stator  32 , the rotary shaft  31 , the rotor  33 , and the bearings  34  as illustrated in  FIG.  2   . 
     The cooling liquid contained in the cooling water channel  51  is supplied from the cooling liquid inlet  53 , flows along a cooling liquid path W in a zigzag shape along the circumferential direction of the inner housing  11  as illustrated in  FIG.  6   , cools both the inner and outer housings  11  and  12 , and then is discharged through the cooling liquid outlet  54 . 
     In this case, the cooling gas flowing through the outer gas channels  41   b  is rapidly cooled by the cooling liquid flowing through the unit water channels  51   a  adjacent to the outer gas channels  41   b . Particularly, due to the cooling fins  52 , heat exchange efficiency between the cooling liquid flowing through the unit water channels  51   a  and the cooling gas flowing through the outer gas channels  41   b  is very high. 
     The above-described turbo compressor  100  includes the compression unit  20  including the compression gas inlet  24  for sucking a gas, the impeller  21  for compressing the gas sucked through the compression gas inlet  24 , the compression gas outlet  25  for discharging the gas compressed by the impeller  21 , and the compression gas channel  26  connected from the compression gas inlet  24  to the compression gas outlet  25 , the motor  30  including the rotary shaft  31  having a front end coupled to the impeller  21 , to rotate the impeller  21 , the housing  10  having the motor accommodation space  13  to accommodate the motor  30 , and the cooling gas channel  41  passing through the motor accommodation space  13  and enabling circulation of a cooling gas contained therein. Since the compression gas channel  26  is spatially separate from the cooling gas channel  41  and thus the gas in the compression gas channel  26  does not permeate into the cooling gas channel  41 , the motor  30  may be efficiently cooled without pressure loss of the compression unit  20 . 
     In the turbo compressor  100 , since the cooling gas channel  41  includes the gas channels  41   a ,  41   b ,  41   c , and  41   d  penetrating through the housing  10  to cool the housing  10 , the housing  10  may be rapidly cooled by using the cooling gas. 
     Furthermore, since the turbo compressor  100  includes the cooling fan  42  for circulating the cooling gas contained in the cooling gas channel  41 , the cooling gas contained in the cooling gas channel  41  may be forcibly circulated. 
     In the turbo compressor  100 , since the cooling fan  42  is provided at a rear end of the rotary shaft  31  and is rotated by rotational force of the rotary shaft  31 , an additional motor for rotating the cooling fan  42  may not be required. 
     Besides, since the turbo compressor  100  includes the cooling water channel  51  for enabling circulation of a cooling liquid therein, an air-cooling function using the cooling gas channel  41  and a water-cooling function using the cooling water channel  51  may be performed at the same time. 
     In the turbo compressor  100 , since the cooling water channel  51  includes the water channels  51   a ,  51   b , and  51   c  penetrating through the housing  10  to cool the housing  10 , compared to a case in which a cooling pipe is separately used, cooling efficiency may be high and the possibility of leakage may be very low. 
     Furthermore, in the turbo compressor  100 , since the cooling water channel  51  is configured to exchange heat with the cooling gas contained in the cooling gas channel  41 , a two-stage cooling structure in which the cooling gas heated by the motor  30  may be rapidly cooled by the cooling liquid may be achieved. 
     In addition, in the turbo compressor  100 , since the cooling fins  52  are provided between the cooling water channel  51  and the cooling gas channel  41 , heat exchange efficiency between the cooling gas and the cooling liquid may be increased. 
     Besides, in the turbo compressor  100 , since the housing  10  includes the inner housing  11  having the motor accommodation space  13 , and the outer housing  12  surrounding the inner housing  11 , and the cooling gas channel  41  is provided between an outer surface of the inner housing  11  and an inner surface of the outer housing  12 , the cooling fins  52  and the cooling gas channel  41  may be easily generated. 
     Although the cooling fins  52  are integrated with an outer circumferential surface of the inner housing  11  in the current embodiment, it will be understood that the cooling fins  52  may also be processed as separate members and then be coupled to the housing  10  by using, for example, press fitting. 
       FIG.  7    is a cross-sectional view of a turbo compressor  200  according to a second embodiment of the present invention. Most elements and effects of the turbo compressor  200  are the same as those of the above-described turbo compressor  100  and thus the following description will be focused on the differences therebetween. 
     The turbo compressor  200  includes a single housing  110  instead of the inner and outer housings  11  and  12 . 
     The unit water channels  51   a  of the turbo compressor  200  extend along a length direction C 1  of the rotary shaft  31 , and the outer gas channels  41   b  of the turbo compressor  200  extend along the length direction C 1  of the rotary shaft  31   
     The unit water channels  51   a  and the outer gas channels  41   b  of the turbo compressor  200  penetrate through the housing  110  and are alternately arranged along a circumferential direction of the rotary shaft  31 , as illustrated in  FIG.  8   . 
     Since the turbo compressor  200  includes a single housing  110  and the cooling gas channel  41  and the cooling water channel  51  penetrate through the housing  110 , the possibility of leakage of a cooling gas and a cooling liquid from the housing  110  may be low. 
     Although the cooling fan  42  is directly coupled to a rear end of the rotary shaft  31  in the afore-described embodiments, it will be understood that the cooling fan  42  may also be driven by a separate electric motor. 
     Although the bearings  34  are provided as air bearings in the afore-described embodiments, it will be understood that other types of bearings may also be used. 
     Although a sealing means for airtightness is not described in the afore-described embodiments, it will be understood that various types of sealing means may be used. 
     While the present invention has been particularly shown and described with reference to embodiments thereof, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the scope of the present invention as defined by the following claims.