Abstract:
A cooling structure for electronic components includes: a case having a refrigerant intake port and a refrigerant channel through which a refrigerant introduced from the refrigerant intake port flows, the refrigerant channel being formed by a wall section; a cooling section having a plurality of flat surfaces formed inside of the case in a manner to interpose the wall section between the flat surfaces and the refrigerant channel; and a plurality of electronic components arranged inside of the case and each of which is in contact with one of the flat surfaces. Each of the electronic components is cooled by the refrigerant via a corresponding flat surface of the flat surfaces and the wall section.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on Japanese Patent Application No. 2014-175703 filed on Aug. 29, 2014, the disclosure of which is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to a cooling structure for electronic components and an electric compressor. 
       BACKGROUND ART 
       [0003]    An in-vehicle electric compressor is generally installed in a periphery of a traveling engine in an engine room, and thus a normal operation of an inverter circuit under a high-temperature atmosphere is essential. For this reason, an electric compressor that has a cooling structure for cooling the inverter circuit by using a refrigerant suctioned into the compressor has been suggested (for example, see Patent Literature 1). 
         [0004]    More specifically, the electric compressor includes: a cylindrical housing that includes a refrigerant inlet port and a refrigerant discharge port; a compression mechanism that is accommodated in the housing to compress the refrigerant sucked from the refrigerant inlet port; an electric motor that is accommodated in the housing to drive the compression mechanism; and the inverter circuit that is attached to an axial end side of the housing to drive the electric motor. 
         [0005]    A cooling plate is arranged between the axial end of the housing and the inverter circuit. A refrigerant passage, through which the refrigerant passes through, is provided between the axial end of the housing and the cooling plate, the refrigerant being sucked from the refrigerant inlet port and flowing toward the compression mechanism. The inverter circuit is cooled by the refrigerant in the refrigerant passage. 
       PRIOR ART LITERATURES 
     Patent Literature 
       [0006]    Patent Literature 1: JP 2009-222009 A 
       SUMMARY OF INVENTION 
       [0007]    In the electric compressor of Patent Literature 1 described above, the refrigerant passage is formed between the axial end of the housing and the cooling plate, and the inverter circuit is cooled by the refrigerant in the refrigerant passage. 
         [0008]    Meanwhile, in reality, downsizing of the electric compressor has been promoted. Accordingly, an installation space, in which electronic components for constituting the inverter circuit are installed, is limited. In addition to the above, of the electronic components, the electronic component that should be cooled the most is desirably arranged at a position that is suited for cooling. However, in order to achieve favorable assemblability of the electronic components, such arrangement may be difficult. Thus, there is a case where performance of the electric compressor cannot sufficiently be realized under the high-temperature environment. 
         [0009]    The present disclosure has a purpose of providing a cooling structure for electronic components, and an electric compressor, in which the electronic components can be sufficiently cooled. 
         [0010]    According to an aspect of the present disclosure, a cooling structure for electronic components includes: a case having a refrigerant intake port and a refrigerant channel through which a refrigerant introduced from the refrigerant intake port flows, the refrigerant channel being formed by a wall section; a cooling section having a plurality of flat surfaces inside of the case in a manner to interpose the wall section between the flat surfaces and the refrigerant channel; and a plurality of electronic components arranged inside of the case and each of which is in contact with one of the flat surfaces. Each of the electronic components is cooled by the refrigerant via a corresponding flat surface of the flat surfaces and the wall section. 
         [0011]    According to the above, the cooling section is constructed of the flat surfaces. Thus, each of the electronic components can be brought into contact with an appropriate flat surface of the flat surfaces in accordance with a physical constitution thereof. Therefore, the electronic components can sufficiently be cooled. 
         [0012]    The wall section means a portion of the case that is filled with a material for constituting the case. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0013]    The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. 
           [0014]      FIG. 1  is a perspective view of exploded states of a compressor section and an inverter device in an in-vehicle electric compressor according to a first embodiment. 
           [0015]      FIG. 2  is a schematic view of a configuration of the in-vehicle electric compressor of the first embodiment. 
           [0016]      FIG. 3  is a cross-sectional view of a single body of a plate in  FIG. 1 . 
           [0017]      FIG. 4  is a view in which the single body of the plate in  FIG. 1  is seen from the other side in an axial direction. 
           [0018]      FIG. 5  is a top view of an inverter case of the inverter device in  FIG. 1 . 
           [0019]      FIG. 6  is a cross-sectional view of the inverter device in  FIG. 1 . 
           [0020]      FIG. 7  is a view in which a single body of the inverter case of the inverter device in  FIG. 1  is seen from the other side in the axial direction. 
           [0021]      FIG. 8  is a view in which the inverter device in  FIG. 1  is seen from one side in the axial direction. 
           [0022]      FIG. 9  is a view in which inside of the inverter device in  FIG. 1  is seen from the other side in the axial direction. 
           [0023]      FIG. 10  is an electric circuit diagram that depicts a configuration of an electric circuit in the inverter device in  FIG. 1 . 
           [0024]      FIG. 11  is a view in which a single body of an inverter case of an inverter device according to a second embodiment is seen from the other side in an axial direction. 
           [0025]      FIG. 12  is a view in which the inverter device in  FIG. 11  is seen from one side in the axial direction. 
           [0026]      FIG. 13  is a cross-sectional view of the inverter device in  FIG. 11 . 
           [0027]      FIG. 14  is a view in which a single body of a plate in  FIG. 13  is seen from the other side in the axial direction. 
           [0028]      FIG. 15  is a cross-sectional view of the single body of the plate in  FIG. 13 . 
           [0029]      FIG. 16  is a cross-sectional view of an inverter device according to a third embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0030]    Hereinafter, embodiments will be described according to the drawings. Same or equivalent portions among respective embodiments below are labeled with same reference numerals in the drawings. 
       First Embodiment 
       [0031]      FIG. 1  and  FIG. 2  illustrate an in-vehicle electric compressor  1  according to a first embodiment, into which a cooling structure for electronic components is applied. 
         [0032]    The in-vehicle electric compressor  1  shown in  FIG. 1  configures a well-known refrigeration cycle apparatus for circulating a refrigerant together with a cooling device, a pressure reducing valve, and an evaporator, and includes a compressor section  10  and an inverter device  20 . The compressor section  10  includes a compressor housing  11 . The compressor housing  11  is formed in a cylindrical shape, one side of which in an axial direction is closed. A refrigerant discharge port  12  is provided on the one side in the axial direction of the compressor housing  11 . 
         [0033]    The compressor housing  11  has legs  11   a ,  11   b ,  11   c ,  11   d . A through hole  11   e  that is penetrated by a bolt (not depicted) is provided in each of the legs  11   a ,  11   b ,  11   c ,  11   d . The bolts are used to fix the compressor housing  11  to a traveling engine. 
         [0034]    An opening is formed on the other side in the axial direction of the compressor housing  11 . A disc-shaped plate  13  is fitted to the opening. 
         [0035]    As depicted in  FIG. 3  and  FIG. 4 , a groove  13   a  is formed on the other side in the axial direction of the plate  13 . On a central side of the plate  13 , the groove  13   a  is formed to be recessed to the one side in the axial direction. The groove  13   a  constitutes a channel  40  with a recessed section  29  of an inverter case  21 . The plate  13  has a refrigerant outlet port  13   b  and a through hole  13   c . The refrigerant outlet port  13   b  is formed to penetrate the groove  13   a . The refrigerant outlet port  13   b  is a hole for guiding the refrigerant into the compressor housing  11 , the refrigerant being suctioned from a refrigerant intake port  23 , which will be described below. The through hole  13   c  is provided to accommodate an airtight terminal  52 , which is depicted in  FIG. 9 . The airtight terminal  52  is a terminal for electrically connecting a circuit board  60  in the inverter device  20  and an electric motor  12   a . The electric motor  12   a  is accommodated in the compressor housing  11  and drives a compression mechanism  12   b . The electric motor  12   a  of the present embodiment constitutes a three-phase AC motor of a synchronous type. The compression mechanism  12   b  is accommodated in the compressor housing  11 , compresses the refrigerant that is suctioned from the refrigerant intake port  23 , which will be described below, and discharges the refrigerant from the refrigerant discharge port  12  toward the cooling device. 
         [0036]    The inverter device  20  includes the inverter case  21 . The inverter case  21  is arranged on the other side of the compressor section  10  in the axial direction. The inverter case  21  is formed in a short cylindrical shape. The inverter case  21  is arranged such that an axis thereof corresponds to an axis of the compressor housing  11 . 
         [0037]    The inverter case  21  includes a side wall  22  that is formed in an annular shape with the axis thereof being the center. The side wall  22  has the refrigerant intake port  23  (see  FIG. 5 ,  FIG. 6 ). 
         [0038]    As depicted in  FIG. 6 , an opening  30  is formed on the other side in the axial direction of the side wall  22 . As depicted in  FIG. 7 , one side in the axial direction of the side wall  22  is closed by a bottom section  24  and a projected section  25 .  FIG. 7  is a view in which a single body of the inverter case  21  is seen from the other side in the axial direction. That is,  FIG. 7  is a view of the inverter case  21  in a state where switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6 , a drive circuit  50 , a capacitor  51 , and the airtight terminal  52  are removed therefrom. 
         [0039]    The projected section  25  is formed to be projected from the bottom section  24  to the other side in the axial direction. As depicted in  FIG. 7 , when seen from the other side in the axial direction, the projected section  25  is formed in a rectangular shape that extends from the refrigerant intake port  23  of the side wall  22  to an axial center side (a lower side in  FIG. 7 ). That is, in the inverter case  21 , the projected section  25  is formed in a rectangular parallelepiped shape. 
         [0040]    A rectangular flat surface  26   a  (a first flat surface) is formed on the other side in the axial direction (that is, on the side adjacent to the opening  30 ) of the projected section  25 . Side surfaces  26   b ,  26   c ,  26   d  as flat surfaces are formed on the projected section  25  on the side adjacent to the side wall  22 . Each of the side surfaces  26   b ,  26   c ,  26   d  is formed to intersect the flat surface  26   a . The side surface  26   b  (a second flat surface) is formed on one side in a radial direction S 1 . The radial direction S 1  is a radial direction with the axial center of the inverter case  21  being the center. The side surface  26   c  is formed on the other side in the radial direction S 1 . The radial direction S 1  is a direction that intersects a radial direction S 2  at right angles, the radial direction S 2  connecting the refrigerant intake port  23  and the axial center. The side surface  26   d  is formed on an opposite side of the refrigerant intake port  23  in the radial direction S 2 . 
         [0041]    A flat surface  27   a  (a third flat surface) is formed on the one side in the radial direction S 1  of the bottom section  24 . A flat surface  27   b  is formed on the other side in the radial direction S 2  of the bottom section  24 . A through hole  28  is formed on the other side in the radial direction S 1  of the bottom section  24 . The through hole  28  is formed to communicate with the through hole  13   c  of the plate  13 . The through holes  28 ,  13   c  each constitute the hole for accommodating the airtight terminal  52 . 
         [0042]    The recessed section  29  (see  FIG. 6 ,  FIG. 8 ) that is recessed to the other side in the axial direction is formed on the one side in the axial direction of the projected section  25 . 
         [0043]    The recessed section  29  is formed by a wall section  25   a  and is constructed of side surfaces  29   a ,  29   b ,  29   c ,  29   d  and a ceiling surface  29   e . The wall section  25   a  is not a portion of the inverter case  21  that is filled with the refrigerant or air but is a portion of the inverter case  21  that is filled with a metallic material for constituting the inverter case  21 . The wall section  25   a  indicates a wall section of the inverter case  21  that constitutes the projected section  25 . 
         [0044]    The side surface  29   a  is formed on one side in the radial direction S 2 . A through hole  31   b  that communicates with the refrigerant intake port  23  is opened in the side surface  29   a . That is, the inside of the recessed section  29  communicates with the refrigerant intake port  23 . The side surface  29   b  is formed on the other side in the radial direction S 2 . The side surface  29   c  is formed on the one side in the radial direction S 1 . The side surface  29   d  is formed on the other side in the radial direction S 1 . The ceiling surface  29   e  is formed on the other side in the axial direction. 
         [0045]    In a state of being closed by the groove  13   a  of the plate  13 , the recessed section  29 , which is configured just as described, constitutes the channel  40 . The channel  40  is formed by the wall section  25   a  of the inverter case  21  and a wall section  13   f  of the plate  13 . The wall section  13   f  is a portion of the plate  13  that is filled with a metallic material for constituting the plate  13 . A cooling fin  31  is provided in the channel  40 . The cooling fin  31  promotes heat exchange between the refrigerant in the channel  40  and cooling targets. The cooling targets of the present embodiment are the switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6 , the drive circuit  50 , and the capacitor  51 . 
         [0046]    More specifically, the cooling fin  31  is constructed of thin plate materials  31   a . Each of the thin plate materials  31   a  is formed in a thin film shape that extends in the radial direction S 2  and the axial direction. The thin plate materials  31   a  are aligned in the radial direction S 1 . Between the two adjacent thin plate materials  31   a  of the thin plate materials  31   a , a channel, through which the refrigerant suctioned from the refrigerant intake port  23  flows toward the refrigerant outlet port  13   b  as indicated by arrows Y 1 , Y 2  in  FIG. 6  and  FIG. 8 , is formed for two each of the adjacent thin plate materials  31   a . The arrow Y 2  in  FIG. 8  indicates a state where a flow (the arrow) of the refrigerant is directed to a near side in a perpendicular direction of the sheet. Each of the thin plate materials  31   a  is supported by the side surface  29   b  and the ceiling surface  29   e.    
         [0047]    In the present embodiment that is configured as described above, the flat surface  26   a  and the side surfaces  26   b ,  26   c ,  26   d  of the projected section  25  are formed to surround the cooling fin  31 . 
         [0048]    The switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6 , the drive circuit  50 , the capacitor  51 , and the airtight terminal  52  are arranged in the inverter case  21 . 
         [0049]    Each of the switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6  is formed in a thin film shape. The drive circuit  50  is formed in a thin film shape. Each of the switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6  and the drive circuit  50  is in contact with the flat surface  26   a  of the projected section  25 . The switching elements SW 1  to SW 6  are arrayed in matrix of (2×3) on the flat surface  26   a  adjacent to the refrigerant intake port  23 . The drive circuit  50  is arranged on the flat surface  26   a  adjacent to the refrigerant outlet port  13   b  (a lower side in  FIG. 9 ) with respect to the switching elements SW 1  to SW 6 . 
         [0050]    Each of the switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6  and the drive circuit  50  of the present embodiment is mounted on the circuit board  60 . In the inverter case  21 , the circuit board  60  is arranged on the other side in the axial direction with respect to the switching elements SW 1  to SW 6  and the drive circuit  50 . 
         [0051]    In the inverter case  21 , the capacitor  51  is arranged on the one side in the radial direction S 1  with respect to the projected section  25 . The capacitor  51  is formed in a rectangular parallelepiped shape and is in contact with the side surface  26   b  and the flat surface  27   a . The capacitor  51  is connected to the circuit board  60  via terminals  51   a ,  51   b . The terminals  51   a ,  51   b  are arranged on the other side in the axial direction of the capacitor  51 . 
         [0052]    The switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6 , the drive circuit  50 , and the capacitor  51  constitute an inverter circuit that outputs a three-phase AC current to the electric motor  12   a . A configuration of an electric circuit in the inverter circuit will be described below. 
         [0053]    In the inverter case  21 , the airtight terminal  52  is arranged on the other side in the radial direction S 1  with respect to the projected section  25 . The airtight terminal  52  is connected to the circuit board  60  via terminals  52   a ,  52   b ,  52   c . The terminals  52   a ,  52   b ,  52   c  are arranged on the other side in the axial direction of the airtight terminal  52 . 
         [0054]    As depicted in  FIG. 1 , the inverter device  20  includes a lid  70 . The lid  70  is formed to close the opening  30  of the inverter case  21 . Connectors  71 ,  72  are connected to the lid  70 . The connectors  71 ,  72  are connected to the circuit board  60 . 
         [0055]    The lid  70  is fixed to the compressor housing  11  by units (six in  FIG. 1 ) of bolts  73 . Each of the units (six in  FIG. 1 ) of the bolts  73  is fastened to the compressor housing  11  through a through hole  21   a  (see  FIG. 9 ) of the inverter case  21 . In this way, the inverter case  21  and the lid  70  are fixed to the compressor housing  11  by the units of the bolts  73 . 
         [0056]    Each of the compressor housing  11 , the plate  13 , the inverter case  21 , and the cooling fin  31  ( 32 ,  33 ) of the present embodiment is molded from a metallic material, such as aluminum, stainless steel (SUS), or cast iron. 
         [0057]    Next, a description will be made on a configuration of an electric circuit in an inverter circuit  80  of the present embodiment with reference to  FIG. 10 . 
         [0058]    Transistors SW 1 , SW 3 , SW 5  are connected to a positive electrode bus  84 . A positive electrode of a high-voltage power supply  82  is connected to the positive electrode bus  84 . Transistors SW 2 , SW 4 , SW 6  are connected to a negative electrode bus  86 . A negative electrode of the high-voltage power supply  82  is connected to the negative electrode bus  86 . 
         [0059]    The transistors SW 1 , SW 2  are connected in series between the positive electrode bus  84  and the negative electrode bus  86 . The transistors SW 3 , SW 4  are connected in series between the positive electrode bus  84  and the negative electrode bus  86 . The transistors SW 5 , SW 6  are connected in series between the positive electrode bus  84  and the negative electrode bus  86 . 
         [0060]    A common connection terminal T 1  between the transistors SW 1 , SW 2  is connected to a U-phase coil of a stator coil of the electric motor  12   a . A common connection terminal T 2  between the transistors SW 3 , SW 4  is connected to a V-phase coil of the stator coil of the electric motor  12   a . A common connection terminal T 3  between the transistors SW 5 , SW 6  is connected to a W-phase coil of the stator coil of the electric motor  12   a . Each of the transistors SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6  is constructed of any of various types of semiconductor switching elements, such as an insulated gate bipolar transistor (an IGBT), and a reflux diode. The capacitor  51  is connected between the positive electrode bus  84  and the negative electrode bus  86  of the inverter circuit  80  and stabilizes a voltage that is provided between the positive electrode bus  84  and the negative electrode bus  86  from the high-voltage power supply  82 . The drive circuit  50  controls the switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6 . 
         [0061]    In the present embodiment that is configured as described above, the flat surface  26   a  and the side surface  26   b  of the projected section  25  constitute a cooling section  90  for cooling the capacitor  51 , the drive circuit  50 , and the switching elements SW 1  to SW 6 . 
         [0062]    Next, a description will be made on a manufacturing method of the inverter device  20  of the present embodiment. 
         [0063]    First, the capacitor  51  and the airtight terminal  52  are accommodated in the inverter case  21 . At this time, the capacitor  51  is brought into contact with the side surface  26   b  of the projected section  25  and the flat surface  27   a . The airtight terminal  52  is fixed to the flat surface  27   b  of the inverter case  21  in a state of being fitted to the through holes  28 ,  13   c.    
         [0064]    Next, the circuit board  60 , on which the switching elements SW 1  to SW 6  and the drive circuit  50  are mounted in advance, is accommodated in the inverter case  21 . At this time, the switching elements SW 1  to SW 6  and the drive circuit  50  are arrayed on the flat surface  26   a  of the projected section  25 . In this way, the switching elements SW 1  to SW 6  and the drive circuit  50  are brought into contact with the flat surface  26   a  of the projected section  25 . In this state, the circuit board  60  is fixed to the inverter case  21 . 
         [0065]    Next, the lid  70  is arranged on the inverter case  21  so as to close the opening  30  of the inverter case  21 . The lid  70  and the inverter case  21  are fixed to the compressor housing  11  by the units of the bolts  73 . 
         [0066]    Next, a description will be made on an operation of the inverter device  20  of the present embodiment. 
         [0067]    First, the drive circuit  50  controls the switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6 . Accordingly, each of the switching elements SW 1  to SW 6  performs switching. In conjunction with this, the three-phase AC current is output from the common connection terminals T 1 , T 2 , T 3  to the stator coil of the electric motor  12   a  on the basis of the output voltage of the capacitor  51 . At this time, the electric motor  12   a  outputs rotational output thereof to the compression mechanism  12   b . Thus, the compression mechanism  12   b  is driven by the electric motor  12   a  and performs an operation of compressing the refrigerant. At this time, the refrigerant from the evaporator side passes through the refrigerant intake port  23 , the through hole  31   b , the channel  40 , the refrigerant outlet port  13   b  of the plate  13 , and the electric motor  12   a  and is suctioned to the compression mechanism  12   b . The compression mechanism  12   b  compresses the suctioned refrigerant and discharges the high-temperature, high-pressure refrigerant from the refrigerant discharge port  12  toward the cooling device. 
         [0068]    Each of the switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6 , the capacitor  51 , and the drive circuit  50  generates heat. Meanwhile, each of the switching elements SW 1  to SW 6  and the drive circuit  50  exchanges heat with the refrigerant in the channel  40  via the wall section  25   a  and the flat surface  26   a  of the projected section  25 . Accordingly, the switching elements SW 1  to SW 6  and the drive circuit  50  are cooled by the refrigerant in the channel  40 . 
         [0069]    The heat is exchanged between the capacitor  51  and the refrigerant in the channel  40  via the wall section  25   a  and the side surface  26   b  of the projected section  25 . Accordingly, the capacitor  51  is cooled by the refrigerant in the channel  40 . 
         [0070]    According to the present embodiment that has been described so far, the inverter device  20  includes the inverter case  21 , the switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6 , the drive circuit  50 , and the capacitor  51 . The side wall  22  of the inverter case  21  has the refrigerant intake port  23 . The one side in the axial direction of the side wall  22  is closed by the bottom section  24  and the projected section  25 . The recessed section  29  that is recessed to the other side in the axial direction is formed on the one side in the axial direction of the projected section  25 . In the state of being closed by the groove  13   a  of the plate  13 , the recessed section  29  constitutes the channel  40 . The channel  40  is formed by the wall section  25   a  of the inverter case  21  and the wall section  13   f  of the plate  13 . The channel  40  communicates with the refrigerant intake port  23  through the through hole  31   b  and also communicates with the refrigerant outlet port  13   b  of the plate  13 . Along with the compressing operation of the compression mechanism  12   b , the refrigerant flows in an order of the refrigerant intake port  23 , the through hole  31   b , the channel  40 , the refrigerant outlet port  13   b  of the plate  13 , and the compression mechanism  12   b . In this way, the refrigerant channel is three-dimensionally configured in the inverter case  21 . 
         [0071]    The drive circuit  50  and the switching elements SW 1  to SW 6  are in contact with the flat surface  26   a  of the projected section  25 . The capacitor  51  is in contact with the side surface  26   b  of the projected section  25 . Just as described, the flat surface  26   a  and the side surface  26   b  of the projected section  25  constitute the cooling section  90  for cooling the capacitor  51 , the drive circuit  50 , and the switching elements SW 1  to SW 6 . The drive circuit  50  and the switching elements SW 1 , . . . SW 6  are cooled by the refrigerant in the channel  40  via the flat surface  26   a  and the wall section  25   a . The capacitor  51  is cooled by the refrigerant in the channel  40  via the wall section  25   a  and the side surface  26   b  of the projected section  25 . 
         [0072]    According to what has been described so far, each of the drive circuit  50 , the capacitor  51 , and the switching elements SW 1  to SW 6  can be brought into contact with an appropriate flat surface of the flat surface  26   a  and the side surface  26   b  of the projected section  25  in accordance with a physical constitution thereof. Accordingly, the drive circuit  50 , the capacitor  51 , and the switching elements SW 1  to SW 6  can sufficiently be cooled in the electric compressor. Thus, the inverter circuit  80 , which is constructed of the switching elements SW 1  to SW 6 , the drive circuit  50 , and the capacitor  51 , can be sufficiently cooled under a high-temperature environment in an engine room, and performance of the in-vehicle electric compressor  1  can be improved in a wide range. Therefore, a frequency at which the inverter circuit  80  is stopped due to a temperature constraint can be reduced. 
         [0073]    In the present embodiment, the switching elements SW 1  to SW 6  are arranged in a portion that is closer to the refrigerant intake port  23  than the drive circuit  50  and the capacitor  51 . The switching elements SW 1  to SW 6  generate a larger amount of heat generation than the drive circuit  50  and the capacitor  51 . 
         [0074]    Accordingly, the switching elements SW 1  to SW 6  are arranged in the portion that is closer to the refrigerant intake port  23  than the drive circuit  50  and the capacitor  51 , each of which generates the smaller amount of heat generation than the switching elements SW 1  to SW 6 . Thus, a sufficient cooling effect of the switching elements SW 1  to SW 6  can be obtained. Therefore, heat resistance of the entire inverter circuit (the electronic circuit)  80  can be improved. 
         [0075]    In the present embodiment, the switching elements SW 1  to SW 6  generate the larger amount of heat generation than the drive circuit  50  and the capacitor  51 . Accordingly, the switching elements SW 1  to SW 6  are required to be cooled the most in comparison with the drive circuit  50  and the capacitor  51 . For this reason, in the present embodiment, the switching elements SW 1  to SW 6  are arranged on the flat surface  26   a  of the projected section  25 , the flat surface  26   a  being formed on the other side in the axial direction. Thus, the switching elements SW 1  to SW 6  can proactively and easily be arranged far from the compressor housing  11  as a heat generating body, and heat insulation performance is thereby improved. 
         [0076]    In the present embodiment, the cooling fin  31  is arranged in the channel  40 . Accordingly, the heat exchange between the refrigerant and each of the switching elements SW 1  to SW 6 , the drive circuit  50 , and the capacitor  51  is promoted. Thus, the switching elements SW 1  to SW 6 , the drive circuit  50 , and the capacitor  51  can reliably be cooled. 
         [0077]    In the present embodiment, the flat surface  26   a  and the side surfaces  26   b ,  26   c ,  26   d  of the projected section  25  are formed to surround the cooling fin  31 . Thus, the flat surface  26   a  and the side surfaces  26   b ,  26   c ,  26   d  as cooling surfaces can three-dimensionally be configured, and the number of electronic components as the cooling targets can easily be increased. 
       Second Embodiment 
       [0078]    In the above first embodiment, the description has been made in which the capacitor  51  is cooled by the refrigerant in the channel  40  via the side surface  26   b  of the projected section  25 . In addition to the above, a description will be made in which a capacitor  51  of a second embodiment is cooled by a refrigerant via a bottom section  24 . 
         [0079]      FIG. 11 ,  FIG. 12 , and  FIG. 13  depict an inverter device  20  of the second embodiment.  FIG. 11  is a view in which inside of a single body of an inverter case  21  of the present embodiment is seen from the other side in an axial direction.  FIG. 12  is a view in which the single body of the inverter case  21  is seen from one side in the axial direction.  FIG. 13  is a cross-sectional view of the inside of the inverter device  20 . 
         [0080]    Similar to the above first embodiment, the inverter case  21  has the bottom surface  24  and a projected section  25 . The projected section  25  has recessed sections  110   a ,  110   b . Each of the recessed sections  110   a ,  110   b  is formed by a wall section  25   a  and is formed to be recessed from the one side in the axial direction to the other side in the axial direction of the projected section  25 . The recessed section  110   a  (a first recessed section) is arranged adjacent to a refrigerant intake port  23  with respect to the recessed section  110   b . The recessed section  110   b  (a second recessed section) is formed adjacent to an axial center of the inverter case  21 . 
         [0081]    As depicted in  FIG. 12 , a groove  110   c  (a third recessed section) is formed on the one side in the axial direction with respect to the bottom section  24  in the inverter case  21 . The groove  110   c  is formed by a wall section  24   a  and is formed to extend between the recessed sections  110   a ,  110   b  on the side adjacent to the bottom section  24 . That is, the groove  110   c  is formed to bypass the portion between the recessed sections  110   a ,  110   b  in an inverted C-shape when seen from the one side in the axial direction. Similar to the wall section  25   a , the wall section  24   a  of the present embodiment is a portion of the inverter case  21  that is filled with a metallic material for constituting the inverter case  21 . The wall section  24   a  indicates a wall section of the inverter case  21  that constitutes the bottom section  24 . 
         [0082]    As depicted in  FIG. 13 , similar to the above first embodiment, a plate  13  is arranged on the one side in the axial direction of the inverter case  21 . 
         [0083]    As depicted in  FIG. 14  and  FIG. 15 , a groove  13   d  is formed on the one side in the axial direction of the plate  13  of the present embodiment. As depicted in  FIG. 14 , the groove  13   d  is formed in a C-shape when seen from the other side in the axial direction. The groove  13   d  is formed with a refrigerant outlet port  13   b . The refrigerant outlet port  13   b  is arranged on and penetrates an axial center side of the plate  13  in the axial direction. The groove  13   d  is formed to overlap the recessed section  110   a , the groove  110   c , and the recessed section  110   b  in the axial direction. 
         [0084]    The recessed section  110   a  and the groove  13   d  constitute a channel  41  (a first channel). The recessed section  110   b  and the groove  13   d  constitute a channel  42  (a second channel). The groove  110   c  and the groove  13   d  constitute a bypass channel  43 . The bypass channel  43  constitutes a refrigerant channel that communicates with the channels  41 ,  42  and bypasses toward the bottom section  24 . 
         [0085]    The recessed section  110   a  is formed by side surfaces  29   a ,  29   b ,  29   c ,  29   d  and a ceiling surface  29   e . The recessed section  110   b  is formed by side surfaces  34   a ,  34   b ,  34   d ,  34   e  and a ceiling surface  34   c.    
         [0086]    A cooling fin  32  is provided in the channel  41 . The cooling fin  32  is constructed of thin plate materials  32   a . Each of the thin plate materials  32   a  is formed in a thin film shape that extends in a radial direction S 2  and the axial direction. The thin plate materials  32   a  are aligned in a radial direction S 1 . Between the two adjacent thin plate materials  32   a  of the thin plate materials  32   a , a channel, through which the refrigerant suctioned from the refrigerant intake port  23  flows toward the bypass channel  43  as indicated by arrows Y 4 , Y 5  in  FIG. 12  and  FIG. 13 , is formed for two each of the adjacent thin plate materials  32   a . Each of the thin plate materials  32   a  is supported by the side surface  29   b  and the ceiling surface  29   e.    
         [0087]    A cooling fin  33  is provided in the channel  42 . The cooling fin  33  is constructed of thin plate materials  33   a . Each of the thin plate materials  33   a  is formed in a thin film shape that extends in the radial direction S 2  and the axial direction. The thin plate materials  33   a  are aligned in the radial direction S 1 . Between the two adjacent cooling fins  33  of the thin plate materials  33   a , a channel, through which the refrigerant flows from the bypass channel  43  toward the refrigerant outlet port  13   b , is formed for two each of the cooling fins  33  as indicated by the arrows Y 4 , Y 5  in  FIG. 12  and  FIG. 13 . Each of the thin plate materials  33   a  is supported by the side surface  34   a  and the ceiling surface  34   c.    
         [0088]    In the present embodiment that is configured as described above, the flat surface  26   a  and the side surfaces  26   b ,  26   c ,  26   d  of the projected section  25  are formed to surround the cooling fins  32 ,  33 . Similar to the above first embodiment, switching elements SW 1  to SW 6  and a drive circuit  50  of the present embodiment are in contact with the flat surface  26   a  of the projected section  25 . The capacitor  51  is in contact with the side surface  26   b  of the projected section  25  and a flat surface  27   a  of the bottom section  24 . 
         [0089]    The side surface  26   b  and the flat surface  26   a  of the projected section  25  and the flat surface  27   a  of the bottom section  24  constitute a cooling section  90  for cooling the capacitor  51 , the drive circuit  50 , and the switching elements SW 1  to SW 6 . 
         [0090]    Next, a description will be made on an operation of the inverter device  20  of the present embodiment. 
         [0091]    In the present embodiment, when a compression mechanism  12   b  is driven by an electric motor  12   a  and performs an operation of compressing the refrigerant, the refrigerant from an evaporator side flows in an order of the refrigerant intake port  23 , a through hole  31   b , the channel  41 , the bypass channel  43 , and the channel  42 . The refrigerant flows into a compressor housing  11  from the refrigerant outlet port  13   b.    
         [0092]    At this time, the switching elements SW 1  to SW 6  are cooled by the refrigerant in the channel  41  via the wall section  25   a  and the flat surface  26   a  of the projected section  25 . The drive circuit  50  is cooled by the refrigerant in the channel  42  via the wall section  25   a  and the flat surface  26   a  of the projected section  25 . The capacitor  51  is cooled by the refrigerant in the channel  42  via the wall section  25   a  and the side surface  26   b  of the projected section  25 . The capacitor  51  is cooled by the refrigerant in the bypass channel  43  via the wall section  24   a  and the flat surface  27   a  of the bottom section  24 . 
         [0093]    According to the present embodiment that has been described so far, each of the drive circuit  50 , the capacitor  51 , and the switching elements SW 1  to SW 6  can be brought into contact with an appropriate flat surface of the flat surface  26   a  and the side surface  26   b  of the projected section  25  and the flat surface  27   a  of the bottom section  24  in accordance with a physical constitution thereof. Accordingly, similar to the above first embodiment, the drive circuit  50 , the capacitor  51 , and the switching elements SW 1  to SW 6  can sufficiently be cooled. 
         [0094]    In particular, in the present embodiment, the capacitor  51  is cooled by the refrigerant in the channels  41 ,  42  and the refrigerant in the bypass channel  43 . Accordingly, cooling performance for cooling the capacitor  51  can be improved. 
         [0095]    In the present embodiment, the cooling fin  32  is arranged in the channel  41 . The cooling fin  33  is arranged in the channel  42 . Accordingly, heat exchange between the refrigerant and each of the switching elements SW 1  to SW 6 , the drive circuit  50 , and the capacitor  51  is promoted. Thus, the switching elements SW 1  to SW 6 , the drive circuit  50 , and the capacitor  51  can reliably be cooled. 
       Third Embodiment 
       [0096]    In the above first and second embodiments, the description has been made in which the refrigerant channel is constructed of the plate  13  and the inverter case  21 . Instead of the above, in a third embodiment, a refrigerant channel is constructed of a single body of an inverter case  21 . 
         [0097]      FIG. 16  is a cross-sectional view of an inverter device  20  of the third embodiment. In  FIG. 16 , the same reference sign as that in  FIG. 6  denote the same component. Similar to the above first embodiment, in the inverter case  21  of the inverter device  20  of the present embodiment, one side in an axial direction of a side wall  22  is closed by a bottom section  24  and a projected section  25 . The inverter case  21  defines a refrigerant channel  100 . The refrigerant channel  100  is formed by the single body of the inverter case  21 . That is, the refrigerant channel  100  is formed irrespective of a plate  13 . The refrigerant channel  100  is formed by wall sections  25   a ,  24   a  of the inverter case  21 . Each of the wall sections  25   a ,  24   a  is a portion of the inverter case  21  that is filled with a metallic material for constituting the inverter case  21 . The wall section  25   a  is a wall section of the projected section  25  that forms the refrigerant channel  100 . The wall section  24   a  is a wall section of the bottom section  24  that forms the refrigerant channel  100 . 
         [0098]    A refrigerant intake port  23  of the refrigerant channel  100  is formed in the side wall  22 . A refrigerant outlet port  13   b  of the refrigerant channel  100  is arranged on one side in an axial direction of the inverter case  21 . The refrigerant outlet port  13   b  is opened to the one side in the axial direction. 
         [0099]    The refrigerant channel  100  is formed along a flat surface  26   a  of the projected section  25 , a side surface  26   b , and a flat surface  27   a  of the bottom section  24 . 
         [0100]    A drive circuit  50  and switching elements SW 1  to SW 6  are in contact with the flat surface  26   a  of the projected section  25 . A capacitor  51  is in contact with the side surface  26   b  of the projected section  25  and the flat surface  27   a  of the bottom section  24 . A coil  53  is in contact with the flat surface  27   a  of the bottom section  24  and smoothes a voltage between both terminals of the capacitor  51 . The coil  53  constitutes an inverter circuit  80  with the switching elements SW 1 , SW 2 , SW 3 , SW 4 , SW 5 , SW 6 , the drive circuit  50 , and the capacitor  51 . 
         [0101]    Just as described, the flat surface  26   a  of the projected section  25 , the side surface  26   b  and the flat surface  27   a  of the bottom section  24  constitute a cooling section  90  for cooling the capacitor  51 , the drive circuit  50 , the coil  53 , and the switching elements SW 1  to SW 6 . 
         [0102]    The drive circuit  50  and the switching elements SW 1  to SW 6  are cooled by the refrigerant in the refrigerant channel  100  via the flat surface  26   a  and the wall section  25   a . The capacitor  51  is cooled by the refrigerant in the refrigerant channel  100  via the wall section  25   a  and the side surface  26   b  of the projected section  25 . Each of the capacitor  51  and the coil  53  is cooled by the refrigerant in the refrigerant channel  100  via the wall section  24   a  and the flat surface  27   a  of the bottom section  24 . 
         [0103]    A channel cross-sectional area of a refrigerant channel  100   a  that is formed adjacent to the projected section  25  of the refrigerant channel  100  differs from a channel cross-sectional area of a refrigerant channel  100   b  that is formed adjacent to the bottom section  24  of the refrigerant channel  100 . More specifically, the channel cross-sectional area of the refrigerant channel  100   a  is set to be larger than the channel cross-sectional area of the refrigerant channel  100   b.    
         [0104]    The capacitor  51  is connected to a circuit board  60  via electric terminals  51   a ,  51   b  (one of the electric terminals is depicted in  FIG. 16 ). In addition, the coil  53  is connected to the circuit board  60  via electric terminals  53   a ,  53   b  (one of the electric terminals is depicted in  FIG. 16 ). 
         [0105]    The electric terminals  51   a ,  51   b  are arranged on the other side in the axial direction of the capacitor  51 . The electric terminals  53   a ,  53   b  are arranged on the other side in the axial direction of coil  53 . Accordingly, the capacitor  51  and the coil  53  are arranged such that the electric terminals  51   a ,  51   b ,  53   a ,  53   b  face the same direction. 
         [0106]    According to the present embodiment that has been described so far, the flat surface  26   a  and the side surface  26   b  of the projected section  25  and the flat surface  27   a  of the bottom section  24  constitute the cooling section  90  for cooling the capacitor  51 , the drive circuit  50 , the coil  53 , and the switching elements SW 1  to SW 6 . Accordingly, each of the drive circuit  50 , the capacitor  51 , the coil  53 , and the switching elements SW 1  to SW 6  can be brought into contact with an appropriate flat surface of the flat surface  26   a  and the side surface  26   b  of the projected section  25  and the flat surface  27   a  of the bottom section  24  in accordance with a physical constitution thereof. Thus, similar to the above first embodiment, the drive circuit  50 , the capacitor  51 , and the switching elements SW 1  to SW 6  can sufficiently be cooled. 
         [0107]    In the present embodiment, when the capacitor  51 , the coil  53 , and the circuit board  60  are assembled in the inverter case  21 , similar to the above first embodiment, the capacitor  51  and the coil  53  are accommodated in the inverter case  21  in advance, and the circuit board  60  is then arranged in the inverter case  21 . Then, the capacitor  51  is connected to the circuit board  60  via the electric terminals  51   a ,  51   b . Furthermore, the coil  53  is connected to the circuit board  60  via the electric terminals  53   a ,  53   b.    
         [0108]    The electric terminals  51   a ,  51   b  of the capacitor  51  and the electric terminals  53   a ,  53   b  of the coil  53  are arranged to face the same direction (an upper side in  FIG. 16 ). Accordingly, when the capacitor  51  and the coil  53  are assembled to the circuit board  60 , the circuit board  60  can be assembled from the same direction with respect to the capacitor  51  and the coil  53 . Thus, an assembling process of the circuit board  60  can be simplified. 
         [0109]    In the present embodiment, an amount of heat generation of the capacitor  51  is larger than an amount of heat generation of the coil  53 . For this reason, the capacitor  51  is in contact with the side surface  26   b  of the projected section  25  and the flat surface  27   a  of the bottom section  24 . The coil  53  is in contact with the flat surface  27   a  of the bottom surface  24 . That is, the number of the flat surfaces that the capacitor  51  is in contact is larger than the number of the flat surfaces that the coil  53  is in contact. In other words, the capacitor  51  and the coil  53  are set such that the number of contacting flat surfaces differs in accordance with the amount of heat generation. In this way, both of improvement of cooling performance of the capacitor  51  and the coil  53  and downsizing of the inverter case  21  can be achieved in a small space in the inverter case  21 . 
         [0110]    In the present embodiment, the channel cross-sectional area of the refrigerant channel  100   a  is set to be larger than the channel cross-sectional area of the refrigerant channel  100   b . A flow rate of the refrigerant that flows through the refrigerant channel  100   a  is lower than a flow rate of the refrigerant that flows through the refrigerant channel  100   b . Thus, the switching elements SW 1  to SW 6 , the drive circuit  50 , and the capacitor  51 , which are in contact with the projected section  25 , can reliably be cooled. 
       Other Embodiments 
       [0111]    In the above third embodiment, the description has been made in which, in the case where the amount of heat generation of the capacitor  51  is larger than the amount of heat generation of the coil  53 , the number of the flat surfaces that the capacitor  51  is in contact is increased to be larger than the number of the flat surfaces that the coil  53  is in contact. Instead of the above, the following may be adopted. 
         [0112]    More specifically, in the case where the amount of heat generation of the capacitor  51  is smaller than the amount of heat generation of the coil  53 , the number of the flat surfaces that the capacitor  51  is in contact may be reduced to be smaller than the number of the flat surfaces that the coil  53  is in contact. 
         [0113]    In the above third embodiment, the description has been made on the case where the channel cross-sectional area of the refrigerant channel  100   a  is set to be larger than the channel cross-sectional area of the refrigerant channel  100   b . Instead of the above, the channel cross-sectional area of the refrigerant channel  100   a  may be set to be smaller than the channel cross-sectional area of the refrigerant channel  100   b.    
         [0114]    In the above first, second, and third embodiments, a recess or a projection may be provided in the flat surface  26   a  and the side surface  26   b  of the projected section  25  and the flat surface  27   a  of the bottom section  24  in accordance with the physical constitutions of the electronic components, such as the drive circuit  50 , the capacitor  51 , and the switching elements SW 1  to SW 6 . That is, the electronic components are fitted to the recess(es) or the projection(s) of the flat surfaces ( 26   a ,  26   b ,  27   a ) of the case  21 . In this way, the electronic components can be fixed to the flat surfaces of the case  21 , and vibration resistance can thereby be improved. 
         [0115]    In the above first, second, and third embodiments, the description has been made on the example in which the refrigerant intake port  23  of the refrigerant channel in the inverter device  20  is provided on a radially outer side with the axis being the center and the refrigerant outlet port  13   b  is provided on the one side in the axial direction. Instead of the above, the refrigerant intake port  23  may be provided on the other side in the axial direction, and the refrigerant outlet port  13   b  may be provided on the one side in the axial direction. In this way, a flexibility in design of a connection section between the compressor housing  11  and the inverter case  21  can be increased. 
         [0116]    In the above first and second embodiments, the description has been made on the example in which the refrigerant channel is constructed of the plate  13  and the inverter case  21 . Instead of the above, the inverter case  21  that is constructed of split cases may be used, and the refrigerant channel may be constructed of the split cases and the plate  13 . In this way, assemblability of the drive circuit  50 , the capacitor  51 , the switching elements SW 1  to SW 6 , and the inverter case  21  can be improved. 
         [0117]    In the above first, second, and third embodiments, the description has been made on the example in which the one refrigerant channel is configured in the inverter device  20 . Instead of the above, refrigerant channels, through which the refrigerant flows from the evaporator side into the compressor housing  11 , may be formed in the inverter device  20 . In this way, a flexibility in arrangement of the electronic components can be increased. 
         [0118]    In the above first, second, and third embodiments, the description has been made on the example in which a cooling structure for the electronic components is applied to the in-vehicle electric compressor  1 . Instead of the above, the cooling structure for the electronic components may be applied to the electric compressor  1  of a mounted type. Alternatively, the cooling structure for the electronic components may be applied to a device other than the electric compressor  1 . 
         [0119]    It should be appreciated that the present disclosure is not limited to the embodiments described above and can be modified appropriately within the scope of the appended claims. The embodiments above are not irrelevant to one another and can be combined appropriately unless a combination is obviously impossible. In the respective embodiments above, it goes without saying that elements forming the embodiments are not necessarily essential unless specified as being essential or deemed as being apparently essential in principle.