Abstract:
A power supply line for high-frequency current has a two-layered tubular conductor including an inner tube portion and an outer tube portion which is concentric to the inner tube portion and integrally linked thereto by four connecting portions along the entire length in the longitudinal direction. The four connecting portions are circumferentially disposed at predetermined intervals. By providing the four connection portions between the inner tube portion and the outer tube portion, it is possible to more accurately position the inner tube portion and to reduce high frequency resistance when compared with the likes of conventional power supply lines for high-frequency current having only one connecting portion between an inner tube portion and an outer tube portion.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a power supply line for high-frequency current through which a high-frequency current flows, a power supply line manufacturing method and a power supply line holding structure for holding the power supply line. 
       BACKGROUND OF THE INVENTION 
       [0002]    Conventionally, there is available a trolley system including a vehicle, such as a travelling hoist or a transfer mover, and a power supply device for supplying electric power to the vehicle. In the power supply device, electric power is exchanged between a power supply line arranged along a vehicle-travelling rail and a power receiver provided in the vehicle. The electric power received by the power receiver is supplied to the vehicle. One example of the power supply line is disclosed in Patent Document 1. 
         [0003]      FIG. 12  is a perspective view showing the outward appearance of a power supply line for high-frequency current disclosed in Patent Document 1.  FIG. 13  is a vertical section view showing a modified example of the power supply line shown in  FIG. 12 , which employs another conductor formed by extruding copper. As shown in  FIGS. 12 and 13 , the power supply line for high-frequency current  100  includes a two-layered tubular conductor  200  embedded in an insulating body  300 . The conductor  200  includes an inner tube portion  200   a  and a concentric outer tube portion  200   b  one-piece connected to the inner tube portion  200   a  by a connecting portion  200   c  over the longitudinal full length of the conductor  200 . The insulating body  300  is not arranged in the spatial portions  400   a  and  400   b  of the respective tube portions  200   a  and  200   b.    
         [0004]    In the example shown in  FIG. 12 , a conductor  200  is formed by, e.g., bending a single copper plate. More specifically, an inner tube portion  200   a  is formed by bending the central portion of a plate into an annular cross-sectional shape. Two planar piece portions extending downward in  FIG. 12  from the opposite ends of the annular portion forming the inner tube portion  200   a  are formed in a parallel-extending contact relationship with each other. An outer tube portion  200   b  of annular cross-sectional shape concentric with the inner tube portion  200   a  is formed by bending the planar piece portions into an arc shape to surround the inner tube portion  200   a,  bringing the ends of the arc-shaped bent portions into contact with each other and welding the ends of the arc-shaped bent portions together. The two planar piece portions formed in a parallel-extending contact relationship make up a connecting portion  200   c  for interconnecting the inner and outer tube portions  200   a  and  200   b.    
         [0005]    In a trolley system, power supply lines are fixed in place by a line hanger  500  as shown in  FIGS. 14 and 15 . FIG. is a perspective view showing a state that two power supply lines  101  are fixed to a conventional line hanger  500 .  FIG. 15  is a front view of the line hanger  500  shown in  FIG. 14 . As shown in  FIGS. 14 and 15 , the line hanger  500  is used to fix the power supply lines  101  having a circular cross-sectional shape. The line hanger  500  is formed into a substantially U-like shape and includes a pair of holding members  501  and  502  for holding a pair of power supply lines  101  arranged in parallel and a connecting portion  503  for interconnecting the base end portions of the holding members  501  and  502 . In the tip end portions of the holding members  501  and  502 , there are formed recess portions  501 H and  502 H for holding the power supply lines  101 . The recess portions  501 H and  502 H are formed into a shape conforming to the outward shape of the power supply lines  101 , i.e., the cross-sectional shape of sheaths  301  of the power supply lines  101 . Thus, the recess portions  501 H and  502 H can hold the power supply lines  101  in a closely contacted state with no looseness. 
         [0006]      FIG. 16  shows the recess portion  501 H (or  502 H) of the holding member  501  (or  502 ) shown in  FIG. 14  and the power supply line  101  held in the recess portion  501 H (or  502 H). As shown in  FIG. 16 , step-like stoppers  501 Ha (or  502 Ha) are formed inside the recess portion  501 H (or  502 H) of the holding member  501  (or  502 ). The power supply line  101  is locked by the stoppers  501 Ha (or  502 Ha) and is prevented from being removed with ease. 
         [0007]    [Patent Document 1] 
         [0008]    Japanese Patent Application Publication No. 2008-117746 
         [0009]    However, the power supply line for high-frequency current disclosed in Patent Document 1 suffers from the following problems. 
         [0010]    (1) Since the inner tube portion and the outer tube portion are connected by the single connecting portion, the positioning of the inner tube portion becomes unstable and the alternating current resistance tends to increase. In this regard, the high-frequency resistance becomes smallest when the inner and outer tube portions are concentric with each other. 
         [0011]    (2) A higher level of technique and an increased cost are required to form the inner tube portion, the outer tube portion and the connecting portion using a single copper plate. 
         [0012]    (3) Copper is harder than aluminum, poor in extrusion formability (namely, throughput) and expensive. 
         [0013]    The line hanger set forth above suffers from the following problem. Despite the fact that the step-like stoppers are formed in the recess portion of the holding member of the line hanger, the power supply line having a sheath of circular cross-sectional shape is easily removed upward from the holding member. 
         [0014]    Since the holding member of the line hanger is not provided with a structure for restraining the power supply line from rotating in the circumferential direction, a problem is posed in that the power supply line is rotated when installed or repaired, which makes it difficult to keep the power supply line in position. 
       SUMMARY OF THE INVENTION 
       [0015]    In view of the above, the present invention provides a power supply line for high-frequency current and a power supply line manufacturing method, which are capable of increasing the positioning accuracy of an inner tube portion with respect to an outer tube portion and capable of enhancing the forming throughput. 
         [0016]    Furthermore, the present invention provides a power supply line holding structure for use in a system such as a trolley system employing a line hanger for fixing a power supply line, which is capable of preventing the power supply line from being removed upward and capable of reliably performing the positioning of the power supply line. 
         [0017]    In accordance with a first aspect of the present invention, there is provided a power supply line for high-frequency current, which includes a conductor including an inner tube portion, an outer tube portion and a plurality of connecting portions provided between the inner tube portion and the outer tube portion. 
         [0018]    With such configuration, the connecting portions are provided between the inner tube portion and the outer tube portion. It is therefore possible to increase the positioning accuracy of the inner tube portion and to reduce the high-frequency resistance. 
         [0019]    The connecting portions may preferably include raised connecting portions formed on the inner tube portion, the raised connecting portions making contact with an inner surface of the outer tube portion. With such configuration, the inner tube portion and the outer tube portion are formed independently of each other. This makes it possible to enhance the forming throughput and to save the cost. 
         [0020]    The outer tube portion may preferably include guide grooves formed on the inner surface thereof, the raised connecting portions engaging with the guide grooves. This makes it possible to increase the positioning accuracy of the inner tube portion. More specifically, depending on the machining accuracy of the inner surface of the outer tube portion, a deviation may sometimes occur in the position of the inner tube portion if the inner tube portion is rotated with respect to the outer tube portion in the circumferential direction. By fixing the position of the inner tube portion with respect to the outer tube portion, it is possible to prevent the inner tube portion from being deviated in position from the outer tube portion. It goes without saying that the positional deviation may be caused by the machining accuracy of the tip ends of the raised connecting portions as well as the machining accuracy of the inner surface of the outer tube portion. 
         [0021]    The raised connecting portions may preferably be pressed against the inner surface of the outer tube portion. This makes it possible to increase the positioning accuracy of the inner tube portion. 
         [0022]    In accordance with a second aspect of the present invention, there is provided a method for manufacturing a power supply line for high-frequency current, comprising: providing an inner tube portion having a plurality of raised connecting portions formed on an outer surface thereof; fitting an outer tube portion onto the inner tube portion, the outer tube portion having an inner surface surrounding the raised connecting portions; and reducing the diameter of the outer tube portion to obtain a conductor in which the raised connecting portions make contact with the inner surface of the outer tube portion. 
         [0023]    With such configuration, the inner tube portion and the outer tube portion are connected by the raised connecting portions formed on the outer surface of the inner tube portion. It is therefore possible to increase the positioning accuracy of the inner tube portion and to reduce the high-frequency resistance. Since the inner tube portion and the outer tube portion are formed independently of each other, it is possible to enhance the forming throughput and to save the cost as compared with a case where the inner tube portion and the outer tube portion are one-piece formed from a single copper plate. 
         [0024]    The number of the raised connecting portions may preferably be three or more. This makes it possible to increase the positioning accuracy of the inner tube portion. 
         [0025]    Guide grooves engaging with the raised connecting portions may preferably be formed on the inner surface of the outer tube portion. This makes it possible to further increase the positioning accuracy of the inner tube portion. 
         [0026]    The raised connecting portions may preferably be pressed against the inner surface of the outer tube portion by reducing the diameter of the outer tube portion. This makes it possible to prevent the inner tube portion from being deviated in position with respect to the outer tube portion. 
         [0027]    In accordance with a third aspect of the present invention, there is provided a power supply line holding structure, including: a holding member including a recess portion with a stopper; and a power supply line including a sheath having a substantially circular cross-sectional shape, the power supply line being mounted to the recess portion of the holding member, the sheath having a flat shoulder portion engaging, through surface-to-surface contact, with the stopper of the recess portion. 
         [0028]    With such configuration, when the power supply line is fixed to the recess portion of the holding member, the flat shoulder portion of the sheath of the power supply line are caught, through surface-to-surface contact, by the stopper of the recess portion. This makes it possible to prevent the power supply line from being removed upward or making rotation. It is therefore possible to reliably perform the positioning of the power supply line. 
         [0029]    The recess portion of the holding member may preferably have an inner surface and a groove formed on the inner surface, the sheath of the power supply line having a protrusion engaging with the groove. Employing this structure makes it possible to more reliably perform the positioning of the power supply line. 
         [0030]    In accordance with a fourth aspect of the present invention, there is provided a power supply line holding structure, including: a holding member including a recess portion; and a power supply line including a sheath having a substantially circular cross-sectional shape, the power supply line being mounted to the recess portion of the holding member, the recess portion of the holding member having an inner surface and a protrusion formed on the inner surface, the sheath having a groove engaging with the protrusion of the recess portion. 
         [0031]    With such configuration, when the power supply line is fixed to the recess portion of the holding member, the protrusion provided in on the inner surface of the recess portion engages with the groove provided in the sheath of the power supply line. This makes it possible to reliably prevent the power supply line from being removed upward or making rotation. It is therefore possible to more reliably perform the positioning of the power supply line. 
         [0032]    The present invention can provide a power supply line for high-frequency current and a power supply line manufacturing method, which are capable of increasing the positioning accuracy of an inner tube portion with respect to an outer tube portion and capable of enhancing the forming throughput. 
         [0033]    Furthermore, the present invention can provide a power supply line holding structure for use in a system such as a trolley system employing a line hanger for fixing a power supply line, which is capable of preventing the power supply line from being removed upward and capable of reliably performing the positioning of the power supply line. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    The objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which: 
           [0035]      FIG. 1  is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a first embodiment of the present invention; 
           [0036]      FIG. 2  is a perspective view schematically showing a modified example the conductor of the power supply line shown in  FIG. 1 , which has two connecting portions; 
           [0037]      FIG. 3  is a perspective view schematically showing another modified example the conductor of the power supply line shown in  FIG. 1 , which has three connecting portions; 
           [0038]      FIG. 4  is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a second embodiment of the present invention; 
           [0039]      FIG. 5  is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a third embodiment of the present invention; 
           [0040]      FIG. 6  is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a fourth embodiment of the present invention; 
           [0041]      FIG. 7  is a perspective view illustrating a method for manufacturing the power supply line shown in  FIG. 6 ; 
           [0042]      FIG. 8  is a perspective view illustrating a method for manufacturing the power supply line shown in  FIG. 5 ; 
           [0043]      FIG. 9  is a view showing a power supply line holding structure according to a fifth embodiment of the present invention; 
           [0044]      FIG. 10  is a view showing a power supply line holding structure according to a sixth embodiment of the present invention; 
           [0045]      FIG. 11  is a view showing a power supply line holding structure according to a seventh embodiment of the present invention; 
           [0046]      FIG. 12  is a perspective view showing the outward appearance of a conventional power supply line for high-frequency current; 
           [0047]      FIG. 13  is a vertical section view showing a modified example of the power supply line shown in  FIG. 12 , which employs another conductor formed by extruding copper; 
           [0048]      FIG. 14  is a perspective view showing a state that two power supply lines are fixed to a conventional line hanger; 
           [0049]      FIG. 15  is a front view of the line hanger shown in  FIG. 14 ; and 
           [0050]      FIG. 16  is an enlarged view showing a recess portion of a holding member of a conventional line hanger and a power supply line held in the recess portion. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0051]    Embodiments of the present invention will now be described in detail with reference to the accompanying drawings forming a part of the subject specification. In the respective drawings, identical or similar components will be designated by like reference symbols with no repeated description given thereto. 
       First Embodiment 
       [0052]      FIG. 1  is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a first embodiment of the present invention. Referring to  FIG. 1 , the power supply line for high-frequency current  1  of the present embodiment includes a two-layered tubular conductor  2 . The conductor  2  includes an inner tube portion  2   a  and a concentric outer tube portion  2   b  one-piece connected to the inner tube portion  2   a  by four connecting portions  2   c  over the longitudinal full length of the conductor  2 . Just like the conventional power supply line for high-frequency current  100  shown in  FIGS. 12 and 13 , the conductor  2 , when in use, is embedded in an insulating body  300  which is not shown in  FIG. 1 . The four connecting portions  2   c  interconnecting the inner tube portion  2   a  and the outer tube portion  2   b  are arranged at a specified interval (e.g., at an interval of 90 degrees) in the circumferential direction. 
         [0053]    As set forth above, the power supply line  1  of the present embodiment includes the conductor  2  having the four connecting portions  2   c  provided between the inner tube portion  2   a  and the outer tube portion  2   b.  Therefore, as compared with the conventional power supply line  100  in which only one connecting portion  200   c  exists between the inner tube portion  200   a  and the outer tube portion  200   b,  it is possible to increase the positioning accuracy of the inner tube portion  2   a  with respect to the outer tube portion  2   b  and to reduce the high-frequency resistance. 
         [0054]    The number of the connecting portions  2   c  interconnecting the inner tube portion  2   a  and the outer tube portion  2   b  is not limited to four but may be at least two.  FIG. 2  schematically shows a power supply line for high-frequency current  10  provided with two connecting portions  2   c.    FIG. 3  schematically shows a power supply line for high-frequency current  20  provided with three connecting portions  2   c.  The connecting portions  2   c  are arranged at an interval of 180 degrees in the power supply line  10  shown in  FIG. 2  and at an interval of 120 degrees in the power supply line  20  shown in  FIG. 3 . 
       Second Embodiment 
       [0055]      FIG. 4  is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a second embodiment of the present invention. Referring to  FIG. 4 , the power supply line for high-frequency current  30  of the present embodiment includes a two-layered tubular conductor  31 . The conductor  31  includes an inner tube portion  31   a  which has four raised connecting portions  31   c  and an outer tube portion  31   b  into which the inner tube portion  31   a  is inserted. The four raised connecting portions  31   c  of the inner tube portion  31   a  are arranged at a specified interval (e.g., at in interval of 90 degrees) in the circumferential direction of the inner tube portion  31   a  over the longitudinal full length of the inner tube portion  31   a.  The tip ends of the four raised connecting portions  31   c  have such a height that they can make contact with the inner surface of the outer tube portion  31   b.  By providing the four raised connecting portions  31   c  in the inner tube portion  31   a  and bringing the four raised connecting portions  31   c  into contact with the inner surface of the outer tube portion  31   b,  it is possible to form the inner tube portion  31   a  and the outer tube portion  31   b  independently of each other. This makes it possible to enhance the forming throughput and to save the cost. 
         [0056]    As described above, the power supply line  30  of the present embodiment is configured such that the four raised connecting portions  31   c  are provided in the inner tube portion  31   a  to make contact with the inner surface of the outer tube portion  31   b.  This makes it possible to form the inner tube portion  31   a  and the outer tube portion  31   b  independently of each other. As compared with a conventional example in which an inner tube portion and an outer tube portion are one-piece formed from a single copper plate, it is possible to enhance the forming throughput and to save the cost. 
         [0057]    The number of the raised connecting portions  31   c  is not limited to four but may be at least two as in the first embodiment described earlier. 
       Third Embodiment 
       [0058]      FIG. 5  is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a third embodiment of the present invention. Referring to  FIG. 5 , the power supply line for high-frequency current  40  of the present embodiment includes a two-layered tubular conductor  41 . The conductor  41  includes an inner tube portion  41   a  which has four raised connecting portions  41   c  and an outer tube portion  41   b  into which the inner tube portion  41   a  is inserted. The power supply line  40  of the present invention remains the same as the power supply line  30  of the second embodiment in that the inner tube portion  41   a  is provided with the four raised connecting portions  41   c  but differs from the power supply line  30  of the second embodiment in that guide grooves  41   d  for engaging with the raised connecting portions  41   c  are formed on the inner surface of the outer tube portion  41   b.    
         [0059]    The tip ends of the raised connecting portions  41   c  of the inner tube portion  41   a  are formed into a substantially arc shape. Likewise, the guide grooves  41   d  of the outer tube portion  41   b  are formed into a substantially arc shape. By forming the tip ends of the raised connecting portions  41   c  to have a round shape and forming the guide grooves  41   d  into an arc shape, it is possible to easily bring the raised connecting portions  41   c  into engagement with the guide grooves  41   d.    
         [0060]    Since the guide grooves  41   d  engaging with the raised connecting portions  41   c  are formed on the inner surface of the outer tube portion  41   b  in the power supply line  40  of the present embodiment, it is possible to increase the positioning accuracy of the inner tube portion  41   a.  More specifically, depending on the machining accuracy of the inner surface of the outer tube portion  41   b,  a deviation may sometimes occur in the position of the inner tube portion  41   a  if the inner tube portion  41   a  is rotated with respect to the outer tube portion  41   b  in the circumferential direction. By fixing the tip ends of the raised connecting portions  41   c  of the inner tube portion  41   a  to the guide grooves  41   d  of the outer tube portion  41   b,  it is possible to prevent the inner tube portion  41   a  from being deviated in position from the outer tube portion  41   b.  It goes without saying that the positional deviation may be caused by the machining accuracy of the tip ends of the raised connecting portions  41   c  as well as the machining accuracy of the inner surface of the outer tube portion  41   b.    
         [0061]    While the guide grooves  41   d  and the raised connecting portions  41   c  are formed into a round shape in the present embodiment, they may be formed to have other shapes, e.g., a triangular shape. The number of the raised connecting portions  41   c  is not limited to four but may be at least two as in the first embodiment described earlier. 
       Fourth Embodiment 
       [0062]      FIG. 6  is a perspective view schematically showing a conductor of a power supply line for high-frequency current according to a fourth embodiment of the present invention. Referring to  FIG. 6 , the power supply line for high-frequency current  50  of the present embodiment includes a two-layered tubular conductor  51  just like the power supply line  30  of the second embodiment. The conductor  51  includes an inner tube portion  51   a  which has four raised connecting portions  51   c  and an outer tube portion  51   b  into which the inner tube portion  51   a  is inserted. The power supply line  50  of the present embodiment differs from the power supply line  30  of the second embodiment in that the raised connecting portions  51   c  are pressed against the inner surface of the outer tube portion  51   b.  By pressing the raised connecting portions  51   c  against the inner surface of the outer tube portion  51   b,  it is possible to fix the inner tube portion  51   a  to the outer tube portion  51   b  as in the power supply line  30  of the second embodiment. This makes it possible to prevent positional deviation of the inner tube portion  51   a  with respect to the outer tube portion  51   b.    
         [0063]      FIG. 7  is a perspective view schematically illustrating a method for manufacturing the power supply line  50  of the present embodiment. Referring to  FIG. 7 , the inner tube portion  51   a  having the four raised connecting portions  51   c  on the outer surface thereof is produced and, then, the outer tube portion  51   b  for holding the raised connecting portions  51   c  on the inner surface thereof is produced. Thereafter, the outer tube portion  51   b  is fitted to the inner tube portion  51   a.  Subsequently, the outer tube portion  51   b  is moved through a ring-shaped die  60  having an inner diameter a little smaller than an outer diameter of the outer tube portion  51   b,  thereby reducing the diameter of the outer tube portion  51   b.  As a result, it is possible to obtain a conductor  51  in which the raised connecting portions  51   c  are kept in close contact with the inner surface of the outer tube portion  51   b.  The conductor  51  is embedded in the afore-mentioned insulating body  300  (see  FIGS. 12 and 13 ) to thereby obtain a power supply line for high-frequency current  50 . 
         [0064]    In the power supply line  50  of the present invention, the positioning accuracy of the inner tube portion  51   a  can be increased by pressing the raised connecting portions  51   c  of the inner tube portion  51   a  against the inner surface of the outer tube portion  51   b.    
         [0065]    The number of the raised connecting portions  51   c  is not limited to four but may be at least two as in the first embodiment described earlier. 
         [0066]    In the third embodiment described above, the raised connecting portions  41   c  may be pressed against the inner surface of the outer tube portion  41   b.    FIG. 8  is a perspective view schematically illustrating a method for manufacturing the power supply line  40  of the third embodiment. Referring to  FIG. 8 , the inner tube portion  41   a  having the four raised connecting portions  41   c  on the outer surface thereof is produced and, then, the outer tube portion  41   b  for holding the raised connecting portions  41   c  on the inner surface thereof is produced. In the production of the inner tube portion  41   a,  the tip ends of the raised connecting portions  41   c  are formed into an arc shape. In the production of the outer tube portion  41   b,  the guide grooves  41   d  are formed to have an arc shape. Thereafter, the outer tube portion  41   b  is fitted onto the inner tube portion  41   a.  Subsequently, the outer tube portion  41   b  is moved through a ring-shaped die  70  having an inner diameter a little smaller than an outer diameter of the outer tube portion  41   b,  thereby reducing the diameter of the outer tube portion  41   b.  As a result, it is possible to obtain a conductor  41  in which the raised connecting portions  41   c  are kept in close contact with the guide grooves  41   d  of the outer tube portion  41   b.  The conductor  41  is embedded in the afore-mentioned insulating body  300  (see  FIGS. 12 and 13 ) to thereby obtain a power supply line for high-frequency current  40 . 
       Fifth Embodiment 
       [0067]      FIG. 9  is a view showing a power supply line holding structure according to a fifth embodiment of the present invention. In  FIG. 9 , the same components as those shown in  FIG. 16  are designated by like reference symbols with no description given thereto. 
         [0068]    With the power supply line holding structure shown in  FIG. 9 , a power supply line  11  can be reliably fixed using a line hanger  500  having the same structure as that of the conventional line hanger  500  shown in  FIGS. 14 and 15 . For the details of the line hanger  500 , reference is made to  FIGS. 14 and 15 . 
         [0069]    The power supply line  11  includes the same conductor  200  as that of the conventional power supply line  101  shown in  FIG. 16 . The power supply line  11  differs from the conventional power supply line  101  in that the sheath  5  of the power supply line  11  has flat shoulder portions  5   a  capable of engaging, through surface-to-surface contact, with the stoppers  501 Ha ( 502 Ha) of the recess portion  501 H ( 502 H) of the holding member  501  ( 502 ) of the line hanger  500 . The provision of the flat shoulder portions  5   a  engaging, through surface-to-surface contact, with the stopper pieces  501 Ha ( 502 Ha) of the recess portion  501 H ( 502 H) of the holding member  501  ( 502 ) restrains the power supply line  11  from moving upward. This makes it difficult for the power supply line  11  to be removed upward. Accordingly, it is possible to prevent upward removal of the power supply line  11 . In addition, the rotation of the power supply line  11  is restrained by the shoulder portions  5   a.  This prevents the power supply line  11  from making rotation. As a result, it becomes possible to reliably perform the positioning of the power supply line  11 . 
         [0070]    With the power supply line holding structure of the present embodiment described above, when the power supply line  11  is fixed to the recess portion  501 H ( 502 H) of the holding member  501  ( 502 ), the flat shoulder portions  5   a  of the sheath  5  of the power supply line  11  are caught, through surface-to-surface contact, by the stoppers  501 Ha ( 502 Ha) of the recess portion  501 H ( 502 H) of the line hanger  500 . This restrains the power supply line  11  from moving upward or making rotation. Accordingly, it is possible to prevent the power supply line  11  from being removed upward and to reliably perform the positioning of the power supply line  11 . 
       Sixth Embodiment 
       [0071]      FIG. 10  is a view showing a power supply line holding structure according to a sixth embodiment of the present invention. In the power supply line holding structure of the present embodiment, as shown in  FIG. 10 , a groove  600 H is provided on the bottom surface of the recess portion  501 H ( 502 H) of the holding member  501  ( 502 ) of the line hanger  500 . A protrusion  5   b  engaging with the groove  600 H of the line hanger  500  is provided in the sheath  5 A of a power supply line  12  similar to the power supply line  11  of the fifth embodiment. Since the protrusion  5   b  provided in the sheath  5 A of the power supply line  12  engages with the groove  600 H provided on the bottom surface of the recess portion  501 H ( 502 H) of the holding member  501  ( 502 ) of the line hanger  500 , the rotation of the power supply line  12  is restrained in a more reliable manner as compared with a case where there is provided only the shoulder portions  5   a . Accordingly, it is possible to more reliably perform the positioning of the power supply line  12 . 
         [0072]    With the power supply line holding structure of the present embodiment described above, when the power supply line  12  is fixed to the recess portion  501 H ( 502 H) of the holding member  501  ( 502 ), the protrusion  5   b  provided in the sheath  5 A of the power supply line  12  engages with the groove  600 H provided on the bottom surface of the recess portion  501 H ( 502 H). This restrains the rotation of the power supply line  12  in a more reliable manner. Accordingly, it is possible to reliably perform the positioning of the power supply line  12  in comparison with that in the power supply line holding structure of the fifth embodiment. 
       Seventh Embodiment 
       [0073]      FIG. 11  is a view showing a power supply line holding structure according to a seventh embodiment of the present invention. In the power supply line holding structure of the present embodiment, as shown in  FIG. 11 , protrusions  601 H ( 602 H) are provided on the inner side surfaces of the recess portion  501 H ( 502 H) of the holding member  501  ( 502 ) of the line hanger  500 . Grooves  5   c  engaging with the protrusions  601 H ( 602 H) of the line hanger  500  are provided in the sheath  55  of a power supply line  13  similar to the power supply line  11  of the fifth embodiment. Since the grooves  5   c  provided in the sheath  5 B of the power supply line  13  engages with the protrusions  601 H ( 602 H) provided on the inner side surfaces of the recess portion  501 H ( 502 H), the rotation of the power supply line  13  is restrained in a more reliable manner as compared with a case where there is provided only the shoulder portions  5   a.  Accordingly, it is possible to more reliably perform the positioning of the power supply line  13 . The grooves  5   c  and the protrusions  601 H ( 602 H) restrain rotation of the power supply line  13 , thereby preventing the power supply line  13  from making rotation. As a result, it becomes possible to reliably perform the positioning of the power supply line  13 . 
         [0074]    With the power supply line holding structure of the present embodiment described above, when the power supply line  13  is fixed to the recess portion  501 H ( 502 H) of the holding member  501  ( 502 ), the protrusions  601 H ( 602 H) provided on the inner side surfaces of the recess portion  501 H ( 502 H) engage with the grooves  5   c  provided in the sheath  5 B of the power supply line  13 . This restrains the power supply line  13  from moving upward or making rotation. Accordingly, it is possible to prevent the power supply line  13  from being removed upward and to reliably perform the positioning of the power supply line  13 . 
         [0075]    The fifth through seventh embodiments described above may be provided either independently or in combination. For example, the fifth embodiment and the seventh embodiment may be combined with each other. Alternatively, the sixth embodiment and the seventh embodiment may be combined with each other. 
         [0076]    While the invention has been shown and described with respect to the embodiments, the present invention is not limited thereto. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.