Patent Publication Number: US-2022238273-A1

Title: Soundproofing transformer

Description:
TECHNICAL FIELD 
     The present disclosure relates to a soundproofing transformer. 
     BACKGROUND ART 
     As illustrated in  FIG. 1 , an internal space  11   a  is provided inside a tank  11  forming an outer appearance of a conventional transformer  10 , and the internal space  11   a  is provided with a core  12  and a winding  13 , wound around the core. The internal space  11   a  may be filled with oil, an insulating fluid. 
     Vibrations of the core  12  and the winding  13  may occur inside the tank  11  of the transformer  10 , and the vibrations may be transmitted to the tank  11  of the transformer through a mechanical structure of the transformer and the insulating fluid. 
     In such a process, acoustic sound may be generated, and the generated acoustic sound may be transmitted to a periphery of the transformer  10  as noise. 
     Therefore, there is a need for research on noise reduction, optimized for various designs, standards, and mechanical specifications of the transformer. 
     PRIOR ART DOCUMENT 
     KR 10-1746129 B1 (2017.06.05) 
     DISCLOSURE 
     Technical Problem 
     An aspect of the present disclosure is to reduce noise of a transformer. 
     In addition, an aspect of the present disclosure is to reduce noise in a manner optimized for characteristics of a transformer. 
     Technical Solution 
     According to an aspect of the present disclosure, a soundproofing transformer may include: a tank; a winding portion and a core portion provided inside the tank; an insulating fluid provided inside the tank; a reinforcing member provided outside of the tank; a cavity having a resonance space and connected to the reinforcing member by a coupling member; a partition member stacked on the cavity and having an acoustic absorption portion; a noise inlet member having a first inlet facing the tank, connected to the resonance space, and configured to transmit noise introduced from the first inlet to the resonance space; and a noise reduction panel connected to at least one of the partition member and the noise inlet member, and having a second inlet provided to communicate with the acoustic absorption portion while facing the tank. 
     According to another aspect of the present disclosure, a soundproofing transformer may include: a tank; a winding portion and a core portion provided inside the tank; an insulating fluid provided inside the tank; a reinforcing member provided outside of the tank; a cavity having a resonance space and disposed to face the tank and the reinforcing member; a partition member stacked on the cavity and having an acoustic absorption portion; a noise inlet member having a first inlet facing the tank, connected to the resonance space, and configured to transmit noise introduced from the first inlet to the resonance space; and a noise reduction panel connected to at least one of the partition member and the noise inlet member, and having a second inlet provided to communicate with the acoustic absorption portion while facing the tank. 
     In addition, the cavity may include a noise inlet hole formed on a surface facing the second inlet to communicate with the resonance space. 
     In addition, the noise reduction panel may include the plurality of second inlets. The noise inlet hole may be a hole penetrating the cavity, the plurality of noise inlet holes being provided in the cavity. 
     In addition, the partition member may connect the cavity and the noise reduction panel, and may be provided to separate the noise reduction panel from the cavity. 
     In addition, the partition member may be disposed outside an outer peripheral surface of the second inlet, the noise inlet hole and the noise inlet member to form the acoustic absorption portion on the outer peripheral surface of the noise inlet member. 
     The acoustic absorption portion may be provided with a porous acoustic absorption material. 
     In addition, the plurality of noise inlet members may be provided, and may be provided to be spaced apart from each other by a predetermined distance. 
     In addition, the resonance space of the cavity may have a cylindrical form, a volume (V o ) of the resonance space of the cavity, a length (L eq ) of the noise inlet member, and a cross-sectional area (A) of the inner diameter of the noise inlet member may be determined by a resonance frequency (f H ), the resonance frequency (f H ) may be determined by 
     
       
         
           
             
               
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     γ may be an adiabatic index, P o  may be pressure in the resonance space of the cavity, and ρ may be amass density of a fluid present in the resonance space of the cavity. 
     In addition, the cavity may include a first cavity having a first resonance space, and to which the noise inlet member is connected; and a second cavity having a second resonance space, separated from the first resonance space and to which the noise inlet member is connected, the second cavity being stacked on the first cavity. The noise inlet member connected to the first cavity may be connected to the noise reduction panel through the second resonance space and the acoustic absorption portion. 
     In addition, the cavity may include a first cavity having a first resonance space, and to which the noise inlet member is connected; and a second cavity having a second resonance space separated from the first resonance space, and accommodated in the first resonance space. The noise inlet member connected to the second cavity may be connected to the noise reduction panel through the acoustic absorption portion. 
     In addition, the cavity may include a first cavity having a first resonance space, and to which a first noise inlet member communicating with the first resonance space is connected; and a second cavity having a second resonance space separated or not separated from the first resonance space, and to which a second noise member communicating with the second resonance space is connected. 
     In addition, the first cavity and the second cavity may include a connection hole on a surface facing each other, respectively, and a cover member provided to be coupled or uncoupled to the connection hole to open or close the connection hole may further be included. 
     In addition, a fastening frame connected to the cavity and having at least one fastening hole may further be included. 
     Advantageous Effects 
     According to the present disclosure, it is possible to reduce noise of a transformer. 
     In addition, noise may be reduced in a manner optimized for characteristics of the transformer. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view illustrating a conventional transformer. 
         FIG. 2  is a schematic perspective view illustrating a soundproofing transformer according to an embodiment of the present disclosure. 
         FIG. 3  is schematic view illustrating a partial cross-section in a direction perpendicular to a gravity direction of  FIG. 2 . 
         FIG. 4  is a schematic view illustrating a partial cross-section of a soundproofing transformer according to another embodiment of the present disclosure. 
         FIG. 5  is a schematic view illustrating a partial cross-section of a soundproofing transformer according to another embodiment of the present disclosure. 
         FIG. 6  is a schematic perspective view illustrating a cavity, a partition member, a noise inlet member, a noise reduction panel, and a fastening frame according to an embodiment of the present disclosure. 
         FIG. 7  is a cross-sectional view of  FIG. 6 . 
         FIG. 8  is a schematic cross-sectional view illustrating a cavity, a partition member, a noise inlet member, a noise reduction panel, and a fastening frame according to another embodiment of the present disclosure. 
         FIG. 9  is a schematic cross-sectional view illustrating a cavity, a partition member, a noise inlet member, a noise reduction panel, and a fastening frame according to another embodiment of the present disclosure. 
         FIG. 10  is a schematic view illustrating a cavity and a noise inlet member according to an embodiment of the present disclosure. 
         FIG. 11  is a schematic cross-sectional view illustrating a cavity, a partition member, a noise inlet member, a noise reduction panel, and a fastening frame according to another embodiment of the present disclosure. 
         FIG. 12  is a schematic cross-sectional view illustrating a cavity, a partition member, a noise inlet member, a noise reduction panel, and a fastening frame according to another embodiment of the present disclosure. 
         FIG. 13  is a view illustrating a sound wave absorption coefficient according to a frequency of the embodiments of the present disclosure. 
         FIG. 14  is a schematic cross-sectional view illustrating a cavity, a partition member, a noise inlet member, and a noise reduction panel according to another embodiment of the present disclosure. 
         FIG. 15  is a schematic cross-sectional view illustrating a cavity, a partition member, a noise inlet member, and a noise reduction panel according to another embodiment of the present disclosure. 
         FIG. 16  is a plan view illustrating a cavity, a noise inlet member, and a noise reduction panel according to another embodiment of the present disclosure. 
     
    
    
     BEST MODE FOR INVENTION 
     In order to facilitate understanding of the description of the embodiments of the present disclosure, elements denoted by the same reference numerals in the accompanying drawings are the same element, and among the constituent elements which perform the same function, the related constituent elements are indicated by the number on the same or an extension line. 
     In order to clarify the gist of the present disclosure, descriptions of elements and techniques well known in the related art will be omitted, and the present disclosure will be described in detail with reference to the accompanying drawings. 
     It is to be understood that the present disclosure may, however, be exemplified in many different forms and should not be construed as being limited to specific embodiments set forth herein, but may be suggested by those skilled in the art in other forms in which certain elements are added, alternated, and deleted. 
     In  FIG. 2 , a soundproofing transformer  200  is illustrated in an embodiment of the present disclosure. 
     The soundproofing transformer  200  according to an embodiment of the present disclosure may include a tank  210 , a winding portion  211  and a core portion  212  provided inside the tank, an insulating fluid provided inside the tank, a reinforcing member  220  provided outside of the tank, a cavity  110  having a resonance space  111  and connected to the reinforcing member  220  by a coupling member  230 , a partition member  140  stacked on the cavity  110  and having an acoustic absorption portion  141 , a noise inlet member  120  having a first inlet  132  facing the tank  210  and connected to the resonance space  111  to transmit noise introduced from the first inlet  132  to the resonance space  111 , and a noise reduction panel  130  connected to at least one of the partition member  140  and the noise inlet member  120  and having a second inlet  131  provided to communicate with the acoustic absorption portion  141  while facing the tank  210 . 
     In the soundproofing transformer according to an embodiment of the present disclosure, as illustrated in  FIGS. 3 to 5 , the noise reduction panel  130  may be coupled to the reinforcing member  220  so as to face the tank  210  or the noise reduction panel  130  may be spaced apart from the reinforcing member  220  by a predetermined distance so as to face the reinforcing member  220  and the tank  210 . The tank  210  of transformer may have a space  210   a  for accommodating an insulating fluid. 
     In the soundproofing transformer according to an embodiment of the present disclosure, as illustrated in  FIG. 3 , the cavity  110  may be coupled to the reinforcing member  220  by using the coupling member  230  such that the cavity  110  is interposed between the reinforcing members  220 . 
     In a soundproofing transformer according to another embodiment of the present disclosure, as illustrated in  FIG. 4 , the noise reduction panel  130  may be coupled to the reinforcing member  220  by using the coupling member  230 , such that the cavity  110  covers the reinforcing member  220 . 
     Meanwhile, as illustrated in  FIG. 5 , the cavity  110  may be placed to be spaced apart from the tank  210  and the reinforcing member  220  by a predetermined distance, and these various installation methods may be suitably selected and applied depending on characteristics of the transformer, service environments of the transformer, and the like. 
     A configuration for reducing noise in the present disclosure, as illustrated in  FIGS. 6 to 9 , may include a cavity  110  having a resonance space  111  having a constant volume, a noise inlet member  120  connected to the cavity  110  to communicate with the resonance space  111 , and a noise reduction panel  130  connected to at least one of the cavity  110  and the noise inlet member  120  and having at least one second inlet  131  facing the tank ( 210  of  FIG. 2 ). 
     When describing an embodiment of the present disclosure with reference to  FIG. 7  in more detail, the noise inlet member  120  may include a hollow portion  121  therein, and both end portions of the noise inlet member  120  may be opened. 
     In this case, a side, in which the noise inlet member  120  faces the tank ( 210  of  FIG. 2 ) of the transformer, is a first inlet  132  through which noise is introduced. 
     The hollow portion  121  may be continuous with the first inlet  132 , and may be continuously provided in a longitudinal direction of the noise inlet member  120 . A diameter of the hollow portion  121  may be constant in the longitudinal direction of the noise inlet member  120 . 
     A region of the noise inlet member  120  in which the first inlet  132  is present may be connected to the noise reduction panel  130 , and the other side of the noise inlet member  120  may be connected to the cavity  110 . 
     In connecting the noise inlet member  120  and the cavity  110 , the noise inlet member  120  is connected to the cavity  110  such that the hollow portion  121  of the noise inlet member  120  is connected to the resonance space  111 . 
     The hollow portion  121  of the noise inlet member  120  may be connected to the resonance space  111  and may simultaneously also be provided to communicate with an outside of the cavity  110  and an outside of the noise reduction panel  130 . 
     Therefore, the noise inlet member  120  may be a path through which noise is introduced to the resonance space  111  of the cavity  110 . 
     The resonance space  111  of the cavity  110  may be filled with air, and the air present in the resonance space  111  may act as a spring to cause resonance at a specific frequency. Therefore, noise introduced into the resonance space  111  may be reduced. 
     Specifically, when resonance of the air present in the resonance space  111  of the cavity  110  occurs, a fluid (for example, air) may actively flow in and out through the first inlet  132  and the hollow portion  121  of the noise inlet member  120 , and in this case, the fluid may rub against a tube wall of the noise inlet member  120  to generate thermal energy, thereby allowing acoustic absorption. 
     Meanwhile, the second inlet  131  may be a hole penetrating the noise reduction panel  130  in a direction parallel to the hollow portion  121 . 
     The plurality of the second inlets  131  may be provided on the noise reduction panel  130 , and an inner diameter of the second inlet  131  may be measured in micrometer units. 
     In addition, since the noise blocking performance, that is, the frequency at which resonance is possible, may be adjusted by altering an inner diameter of the second inlet  131 , the size of inner diameter of the second inlet  131  may be appropriately selected depending on operators and work environments and applied, but is not necessarily limited to that of the present disclosure. 
     The second inlet  131  may cause thermal losses and viscous losses of sound waves generated by noise with a wall surface of the noise reduction panel  130 , thereby weakening noise. 
     The thermal losses and the viscous losses of the sound waves may occur in thermal and viscous boundary layers near the wall surface of the noise reduction panel  130 . 
     Therefore, as the number of the second inlet  131  increases and the diameter of the second inlet  131  decreases, an acoustic absorption effect may increase. 
     Therefore, in another embodiment of the present disclosure, as illustrated in  FIG. 8 , a noise inlet hole  114  having a diameter in a micrometer unit may be formed on one surface of the cavity  110  facing the noise reduction panel  130 , thereby further increasing the acoustic absorption effect as described above. 
     In an embodiment of the present disclosure, the noise inlet hole  114  may be a hole penetrating the cavity  110  in a direction parallel to the hollow portion  121  of the noise inlet member  120 . 
     In this case, the noise inlet hole  114  may be a hole penetrating one surface of the cavity  110  to be connected to the resonance space  111  inside the cavity. 
     Further, the noise inlet hole  114  may be provided in a slot shape other than holes. 
     Meanwhile, the partition member  140  according to the present disclosure may serve to connect the cavity  110  and the noise reduction panel  130 , and to separate the noise reduction panel  130  from the cavity  110 . 
     The partition member  140  may be disposed outside of the outer peripheral surface of the noise inlet member  120 , the first inlet  132 , the second inlet  131 , and the noise inlet hole  114  to form the acoustic absorption portion  141  on the outer peripheral surface of the noise inlet member  120 . 
     Accordingly, the partition member  140  may be provided to surround the noise inlet member  120 . 
     The fluid present in the acoustic absorption portion  141  may also act as a spring to contribute to increasing the acoustic absorption effect on the same principle as described above. 
     Further, as illustrated in  FIG. 9 , when the acoustic absorption portion  141  is provided with a porous acoustic absorption material  142 , the acoustic absorption effect may be further increased and the noise may be significantly reduced. 
     A material of the porous acoustic absorption material  142  may be glass fiber, open-cell foam, felted or cast porous ceiling tile, or the like, however, the material is not necessarily limited to the present disclosure. 
     Meanwhile, the plurality of noise inlet members  120  may be provided in the cavity  110 , and the outer peripheries of the noise inlet members  120  may be spaced apart from each other by a predetermined distance. 
     The number of the noise inlet member  120  and the distance in which the noise inlet members  120  are spaced apart may be suitably set based on a frequency at which the resonance space  111  of the cavity  110  resonates. In this case, the frequency at which the resonance space  111  resonates may be generated by noise. 
     As illustrated in  FIG. 10 , in another embodiment of the present disclosure, the cavity may have a cylindrical form, such that the resonance space  111  of the cavity  110  may also have a cylindrical form. 
     In this case, the volume (V) of the resonance space of the cavity, the length (L) of the noise inlet member  120 , and the cross-sectional area (A) of the inner diameter of the noise inlet member  120  may be determined by a resonance frequency (f H ) of the fluid present in the resonance space  111 . 
     A relationship between the resonance frequency (f H , hz) and the volume (V) of the resonance space, the length (L) of the noise inlet member  120 , and the cross-sectional area (A) of the inner diameter of the noise inlet member  120  is expressed by the following Equations 1 and 2. 
     The Equations 1 and 2 are relational expressions necessary for deriving the resonance frequency (f H ). The resonance frequency (f H ) may be generated by noise, and a numerical value thereof may also be determined by noise. 
     
       
         
           
             
               
                 
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     In the accompanied Equations 1 and 2, γ is an adiabatic index, P 0  is pressure of the resonance space ( 111  of  FIG. 1 ), of the cavity, and ρ is a mass density of a fluid (for example, air) present in the resonance space ( 111  of  FIG. 7 ) of the cavity. 
     Therefore, the specification of the volume (V) of the resonance space of the cavity, the length (L) of the noise inlet member  120 , and the cross-sectional area (A) of the inner diameter of the noise inlet member  120  may be determined according to the rated frequency of the transformer, that is, the noise caused from the transformer. 
     A value of the rated frequency of the transformer may be substituted into a value of the resonance frequency (f H ) of the Equations expressed in Equations 1 and 2 to determine the volume (V) of the resonance space of the cavity, the length (L) of the noise inlet member  120 , the cross-sectional area (A) of the inner diameter of the noise inlet member  120 , that is, the cross-sectional area of the hollow portion  121 . 
     The volume (V) of the resonance space  111  of the cavity  110  and the length (L) of the noise inlet member  120 , illustrated in  FIG. 10  are V o  and L eq  in Equation 2, respectively. When calculating by substituting the resonance frequency (f H ) into the Equation expressed Equation 2, A=A of  FIG. 10 , L eq =L of  FIG. 10 , V o =V of  FIG. 10 , and the rated frequency of transformer may be substituted into the resonance frequency (f H ) to be calculated. 
     That is, specifications of the cavity  110  and the noise inlet member  120  may be derived by using the Equations expressed in Equations 1 and 2 with a rated frequency value generated by the transformer. 
     For example, when the transformer having a rated frequency of 60 Hz is applied, volumes of first and second resonance spaces  111   a  and  111   b  of  FIG. 11  may be calculated by the above formula expressed in Equations 1 and 2. 
     The specification relating to the noise inlet member  120  derived from the Equation 2 may be a specification relating to any one of three noise inlet members  120  connected to the second resonance space  111   b , and the volume of the noise inlet member  120  penetrating the second resonance space  111   b  and the acoustic absorption portion  141  and connected to the first resonance space  111   a , may be ignored when calculating the volume of the first resonance space  111   a  and the second resonance space  111   b . Heights of the first and second resonance spaces  111   a  and  111   b  may be equal to each other. 
     In an embodiment of the present disclosure, dimensions in  FIG. 11  may be as follows, B=410 mm, C=414 mm, D=76.5 mm, E=82.5 mm, and F=73.8 mm. 
     In another embodiment of the present disclosure, when a transformer having a rated frequency of 50 Hz is applied, as illustrated in  FIG. 12 , the volume of the second resonance space  111   b  may be ignored when calculating the volume of the first resonance space  111   a , and specifications of the noise inlet members  120  connected to the first resonance space  111   a  and the second resonance space  111   b  may be equal to each other. 
     However, the volume of the second resonance space  111   b  is not specified by the present disclosure. The volume of the second resonance space  111   b  may be suitably selected and applied by those skilled in the art in consideration of the rated frequency of the transformer and the service environment of the transformer. 
     For example, dimensions in  FIG. 12  may be as follows, B=410 mm, C=414 mm, D=102.3 mm, E=108.3 mm, and F=73.8 mm. 
     However, these are only one example, and the detailed specifications may be determined by the transformer (or an environment generating noise). 
     Meanwhile, a sound wave absorption coefficient according to a frequency of a noise reduction apparatus according to  FIGS. 7 and 8  is illustrated in  FIG. 13 . 
     Referring to  FIG. 13 , it can be confirmed that a noise reduction panel  130  having the second inlet  131  and the noise inlet hole  114  (double MPP) and a cavity  110  has a significantly increased sound wave absorption coefficient in a section of 110 Hz to 220 Hz, such that the noise blocking effect is further improved as compared with a noise reduction panel  130  having only the second inlet  131  (single MPP). 
     Meanwhile, as described above, the cavity  110  illustrated in  FIG. 11  may include a first cavity  112  having a first resonance space  111   a  and to which the noise inlet member  120  is connected, and a second cavity  113  having a second resonance space  111   b  separated from the first resonance space  111   a , stacked on an upper portion of the first cavity  112  and to which a plurality of noise inlet members  120  are connected. 
     In this case, the plurality of noise inlet members  120  connected to the second cavity  113  to communicate with the second resonance space  111   b  may be connected to the second cavity  113  through the acoustic absorption portion  141 . 
     The noise inlet member  120  connected to the first resonance space  111   a  may be connected to the noise reduction panel  130  through the second resonance space  111   b  and the acoustic absorption portion  141 . 
     Accordingly, noise may be reduced in various frequency areas while suppressing an increase in the width of the cavity  110 , and utilization of space may be improved. 
     As another aspect, as illustrated in  FIG. 12 , the cavity  110  may include a first cavity  112  having a first resonance space  111   a  and to which the plurality of noise inlet members  120  are connected, and a second cavity  113  having a second resonance space  111   b  separated from the first resonance space  111   a  and accommodated in the first resonance space  111   a.    
     In this case, the noise inlet member  120  connected to the second cavity  113  to communicate with the second resonance space  111   b  may be connected to the noise reduction panel  130  through the acoustic absorption portion  141 . 
     By providing the cavity  110  in plural, utilization of space may be increased and noise may be reduced in various frequency areas. 
     Further, as illustrated in  FIGS. 14 to 16 , a cavity  110  having a matrix structure may be provided. 
     This makes it possible to easily install the cavity  110  and the noise inlet member  120  having a resonance frequency equal to the rated frequency of the transformer, and the cavity  110  and the noise inlet member  120  may be modularized according to the specification of the transformer, thereby further improving convenience in use. 
     In an embodiment of the present disclosure, the cavity  110  may include a first cavity  112  and a second cavity  113  having resonance spaces  111 . 
     More specifically, the cavity  110  may include a first cavity  112  having a first resonance space  111   a , and a second cavity  113  having a second resonance space  111   b.    
     A noise inlet member  120  may be connected to the first cavity  112  and the second cavity  113 , respectively, and a hollow portion  121  of the noise inlet member  120  may be connected to the first resonance space  111   a  and the second resonance space  111   b , respectively. 
     In this case, the first resonance space  111   a  of the first cavity  112  and the second resonance space  111   b  of the second cavity  113  may be separated or may not be separated from each other. 
     To this end, in an embodiment of the present disclosure, the first cavity  112  and the second cavity  113  may include a connection hole  115 , respectively, as illustrated in  FIG. 15 . More specifically, the connection hole  115  may include a first connection hole  115   a  formed on a surface of the first cavity  112  facing the second cavity  113 , and a second connection hole  115   b  formed on a surface of the second cavity  113  facing the first cavity  112 . 
     A cover member  150  may be provided to be coupled to or be uncoupled from the connection hole  115  such that the first cavity  112  and the second cavity  113  may be connected to or separated from each other. 
     The cover member  150  may be provided to be coupled to the connection hole  115  by a bolt, or the like, and may be coupled to the connection hole  115  by a fitting tolerance with the connection hole  115 . 
     According to the connection hole  115  and the cover member  150 , the volume of the cavity  110  may be easily changed, and the convenience and speed of operation in the field may be improved. 
     In addition, a first noise inlet member  122  may be connected to the first cavity  112  to communicate with the first resonance space  111   a , and a second noise inlet member  123  may be connected to the second cavity  113  to communicate with the second resonance space  111   b.    
     The first and second cavities  112  and  113  and the noise reduction panel  130  are connected to each other even when the connection hole  115  is formed in the cavity  110 , and a partition member  140  in which the noise reduction panel  130  is spaced apart from the first and second cavities  112  and  113  to form an acoustic absorption portion  141  between the noise reduction panel  130  and the first and second cavities  112  and  113  may be provided. 
     In this case, the acoustic absorption portion  141  may be provided with a porous sound absorption material ( 142  of  FIG. 9 ) to further improve the noise reduction effect. 
     In addition, in an embodiment of the present disclosure, as illustrated in  FIG. 16 , the cavities  110  may be stacked in plural and modulated. 
     Accordingly, it is possible to easily adjust the specification of the cavity  110  according to the specification of the transformer. 
     While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the present invention, as defined by the appended claims.
           10 ,  200 : transformer     110 : cavity     111 : resonance space     111   a : first resonance space     111   b : second resonance space     112 : first cavity     113 : second cavity     114 : noise inlet hole     115 : connection hole     115   a : first connection hole     115   b : second connection hole     120 : noise inlet member     121 : hollow portion     122 : first noise inlet member     123 : second noise inlet member     130 : noise reduction panel     131 : second inlet     140 : partition member     141 : acoustic absorption portion     142 : porous acoustic absorption material     150 : cover member     160 : fastening frame     161 : fastening hole     210 : tank     211 : winding portion     212 : core portion     220 : reinforcing member     230 : coupling member