Abstract:
During travel of the electric vehicle, the charging arm is extended in the vehicle width direction, a positive electrode overhead line of the power supply device and a positive electrode power reception unit of the charging arm are brought into contact at the same time that a negative electrode overhead line of the power supply device and a negative electrode power reception unit of the charging arm are brought into contact, and a power storage device for driving the electric vehicle is charged. A charging head that is the tip section of the charging arm is held within a V-shaped groove to which the positive electrode overhead line and the negative electrode overhead line are attached, thereby minimizing the loss of contact even if the charging arm shakes in the vertical direction as a result of the condition of the road surface, brake operation, or the like.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a contact charging method and a contact charging system for an electric vehicle, which during traveling of the electric vehicle, charges an electrical storage device provided in the electric vehicle and which is used for driving by way of contact charging from an external power supply device. 
       BACKGROUND ART 
       [0002]    Heretofore, a resonance-type non-contact charging (power supplying) system for a vehicle has been proposed in International Publication No, WO 2011/142421 pamphlet (hereinafter referred, to as WO 2011/142421A). 
       SUMMARY OF INVENTION 
       [0003]    With the resonance-type non-contact, charging (power supplying) system proposed in WO 2011/132421A, as a result of carrying out transmission and reception of high frequency large scale power between a primary side resonator coil on an infrastructure side and a secondary side resonator coil on the side of an electric vehicle, problems occur in that it is likely for generation of external noise to be large, or for control of the power supply to become complex. 
         [0004]    For resolving these problems, a contact charging system, may be considered, which is constituted so as to bring a charging arm, which is provided on an electric vehicle, into contact, with a power supplying device, which is disposed on an external member, during traveling of the electric vehicle, whereby an. electrical storage device of the electric vehicle is charged from the power supplying device through the charging arm. 
         [0005]    However, with such a contact charging system, when the electric vehicle, which is traveling while undergoing charging through the charging arm, swings or rocks in a upper and lower directions (pitching directions) due to road conditions or acceleration and braking operations or the like, contact between the charging arm and the power supplying device becomes unstable, which can lead to a situation in which contact cannot be assured. 
         [0006]    The present invention has been devised taking into consideration the aforementioned problems, and has the object of providing a contact, charging method and a contact charging system for an electric vehicle in which, during traveling while carrying out contact charging between a power supplying device and the electric vehicle through a charging arm of the electric vehicle, even if the electric vehicle undergoes swinging motion in upper and lower directions, loss of assurance of the contact state is suppressed, together with enabling a reduction in size of the electric vehicle charging system. 
         [0007]    A contact charging method for an electric vehicle according to the present invention comprises the steps of providing a power supplying device, which includes a power line retaining part in which a V-shaped groove is provided that faces toward a side portion of the electric vehicle and is formed to open in upper and lower directions of the electric vehicle and to extend in a running direction of the electric vehicle, and in which a positive electrode power line on one inner surface and a negative electrode power line on another inner surface of the V-shaped groove of the power line retaining part are fixed to the power line retaining part respectively along the running direction and at positions to maintain an insulation distance mutually therebetween, and causing a charging arm, which is accommodated in the side portion of the electric vehicle and includes a positive electrode power reception unit and a negative electrode power reception unit, which are provided on a distal end thereof and are disposed so as to face the corresponding positive electrode power line and the corresponding negative electrode power line of the power supplying device, to extend out in a vehicle widthwise direction, and to bring into contact simultaneously the positive electrode power line of the power supplying device and the positive electrode power reception unit of the charging arm, and the negative electrode power line of the power supplying device and the negative electrode power reception unit of the charging arm, and charging an electrical storage device for driving of the electric vehicle. 
         [0008]    A contact charging system for an electric vehicle according to the present invention is constituted from a power supplying device, and the electric vehicle equipped with an electrical storage device for driving to which power from the power supplying device is supplied, wherein the power supplying device is of a structure that includes a power line retaining part in which a V-shaped groove is provided that faces toward a side portion of the electric vehicle and is formed to open in upper and lower directions of the electric vehicle and to extend in a running direction of the electric vehicle, and in which a positive electrode power line on one inner surface and a negative electrode power line on another inner surface of the V-shaped groove of the power line retaining part are fixed to the power line retaining part respectively along the running direction and at positions to maintain an insulation distance mutually therebetween,, and the electric vehicle is of a structure comprising a charging arm configured to extend out in a vehicle widthwise direction, which is accommodated in the side portion of the electric vehicle and includes a positive electrode power reception unit and a negative electrode power reception unit, which are provided on a distal end thereof and are disposed so as to face the corresponding positive electrode power line and the corresponding negative electrode power line of the power supplying device, wherein during charging, the charging arm is extended out in the vehicle widthwise direction, and the positive electrode power line of the power supplying device and the positive electrode power reception unit of the charging arm, and the negative electrode power line of the power supplying device and the negative electrode power reception unit of the charging arm are placed in contact simultaneously, and the electrical storage device is charged. 
         [0009]    According to the present invention, a configuration is provided such that, when the electrical storage device for driving, which is mounted in the electric vehicle, is charged during traveling, by causing the charging arm, which is provided on the vehicle body and on which the positive, electrode power reception unit and the negative electrode power reception unit, are disposed above and below on the distal end thereof, to extend out in a lateral direction of the vehicle body, and to be placed in contact with the power line that is disposed along the running direction of a travel path, the positive electrode power line of the power supplying device and the positive electrode power reception unit, of the charging arm along with the negative electrode power line of the power supplying device and the negative electrode power reception unit of the charging arm, wherein the positive electrode power line is fixed to one inner surface and the negative electrode power line is fixed to another inner surface of the V-shaped groove that faces toward the side portion of the electric vehicle and is formed to open in upper and lower directions of the electric vehicle and to extend along the running direction of the electric vehicle, are brought into contact simultaneously, and the electrical storage device for driving of the electric vehicle is charged. Therefore, even if the charging arm swings or rocks in upper and lower directions due to road conditions or braking operations or the like, the distal end part of the charging arm is retained inside the V-shaped groove, and contact is prevented from not being secured. 
         [0010]    Further, because the positive electrode power line and the negative electrode power line are fixed above and below on inner surfaces of the V-shaped groove, both the power supplying device and the charging arm can be made smaller in scale, and as a result, it is possible for the contact charging system, as a whole to foe made smaller in scale. 
         [0011]    Since the power supplying device carries out charging by way of contact charging, in comparison with a resonance-type non-contact charging system, generation of external noise is greatly reduced, and the power supplying control is simplified. 
         [0012]    The present invention also includes the power supplying device and the charging arm of the above-described contact charging system for an electric vehicle. 
         [0013]    According to the present invention, the positive electrode power reception unit and the negative electrode power reception unit of the charging arm on the side of the vehicle are brought into contact and charging is carried out with respect to the positive electrode power line and the negative electrode power line, which are fixed above and below on inner surfaces of the V-shaped groove extending along the running direction. Therefore, even if the charging arm swings or rocks in upper and lower directions due to road conditions or braking operations or the like, the distal end part of the charging arm is retained inside the V-shaped groove. Then, during traveling of the electric vehicle while contact charging takes place through the charging arm with respect to the power supplying device, contact is prevented from not being secured. Also, a reduction in size of the contact charging system for an electric vehicle can foe achieved. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1A  is a plan view,  FIG. 1B  is a side view, and  FIG. 1C  is a front view of a contact charging system for an electric vehicle, to which a method of the invention according to an embodiment thereof is applied; 
           [0015]      FIG. 2  is a front cross-sectional view with partial omission of a power line retaining part according to a first example that constitutes the contact charging system; 
           [0016]      FIG. 3  is a front view with partial omission of a charging head according to the first example that constitutes the contact charging system; 
           [0017]      FIG. 4  is a plan view with partial omission of a charging arm according to the first example that constitutes the contact charging system; 
           [0018]      FIG. 5  is a perspective view with partial omission showing a contact condition of the charging arm according to the first example with power lines that are retained in a power line retaining part according to the first example that makes up the contact charging system according to a first embodiment; 
           [0019]      FIG. 6  is a front cross-sectional view with partial omission showing a contact condition of the charging arm according to the first example with power lines that are retained in a power line retaining part according to the first example that makes up the contact charging system according to the first embodiment; 
           [0020]      FIG. 7  is a perspective view of a contact condition of the charging arm according to a second example with power lines that are retained in a power line retaining part according to the second example, which makes up a contact charging system, according to a second embodiment; 
           [0021]      FIG. 8  is a front cross-sectional view with partial omission showing a contact condition of the charging arm according to the second example with power lines that are retained in a power line retaining part according to the second example that makes up the contact charging system according to the second embodiment; 
           [0022]      FIG. 9  is a front, view showing a contact condition of the charging arm according to a third example with power lines that are retained in a power line retaining part, according to the first, example that makes up the contact charging system according to a third embodiment; 
           [0023]      FIG. 10  is a side view showing a contact condition of the charging arm according to the third example with power lines that are retained in a power line retaining part according to the first, example that makes up the contact charging system according to the third embodiment; 
           [0024]      FIG. 11  is a side view showing a contact condition of the charging arm according to a modification of the third example with power lines that, are retained in a power line retaining part according to the first, example that makes up the contact charging system according to the modification of the third embodiment; 
           [0025]      FIG. 12  is a side view of the charging arm according to the modification of the third example that, makes up the contact, charging system according to the modification of the third embodiment; 
           [0026]      FIG. 13  is a perspective view of a contact condition of the charging arm according to a fourth example with power lines that are retained in a power line retaining part according to the second example that makes up the contact charging system according to a fourth embodiment; 
           [0027]      FIG. 14  is a front view showing a contact condition of the charging arm according to the fourth example with power lines that are retained in a power line retaining part according to the second example that makes up the contact charging system according to the fourth embodiment; and 
           [0028]      FIG. 15  is a side view showing a contact condition of the charging arm according to the fourth example with power lines that are retained in a power line retaining part according to the second example that makes up the contact charging system according to the fourth embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0029]    Below, descriptions will be given concerning embodiments of the present invention with reference to the accompanying drawings. 
       [Common Structures] 
       [0030]    In  FIGS. 1A, 1B, 1C , there are shown schematic overall structural views of a contact charging system  12  (first embodiment) for an electric vehicle  10  to which a method of the invention according to an embodiment thereof is applied. 
         [0031]    The electric vehicle  10  is a vehicle in which there are mounted an electric motor  110  for vehicle propulsion (shown only in  FIG. 1A ), and an electrical storage device  100  (shown only in  FIG. 1A ) for driving the electric motor  110 . For example, the electric vehicle  10  corresponds to an electrically driven automobile, a hybrid vehicle equipped with an internal combustion engine, and a fuel cell vehicle equipped with a fuel cell, or the like. 
         [0032]    The contact charging system  12  basically is constituted from a power supplying device  26  equipped with a power line retaining part  14  made of an insulating material, and the electric vehicle  10 , which is equipped with a charging arm  18  on a side portion  10   s  of a vehicle body  11 . The charging arm  18  may be disposed on both side portions of the electric vehicle  10 . 
         [0033]    The power supplying device  26  is disposed at a length of a predetermined region on the shoulder of a road (including a high speed expressway) that forms a travel path  70 , or on the shoulder of a travel path  70  of an automobile race track, etc. The length of the predetermined region is set to a length within which it is possible for the electric vehicle  10  having a predetermined electrical consumption to be charged with an amount of charge that enables traveling from the position of one power supplying device  26  to the position of a next power supplying device  26 . 
         [0034]    The electric vehicle  10  travels along the power supplying device  26  on the travel path  70  on which the power supplying device  26  is arranged, and while traveling, charges the electrical storage device  100  from the power supplying device  26  through the charging arm  18 . 
         [0035]    The power line retaining part  14  extends along the length of the predetermined region, and the rear side thereof is fixed at a predetermined interval on a guard post  20  (see  FIG. 1C ). 
         [0036]    Power lines  24 , which are made up from a positive electrode power line  24   p  of a conductive material to which a DC high voltage is applied front an external power supply apparatus (not shown) and a negative electrode power line  24   n  of a conductive material, are fixed to the front side of the power line retaining part  14  like a rail. The voltage may be an AC voltage instead of a DC voltage. 
         [0037]    On a charging head  34  that forms the distal end part of the charging arm  18 , a power reception unit  36  is attached, which is made up from a positive electrode power reception unit  36   p  that contacts the positive electrode power line  24   p,  and a negative electrode power reception unit  36   n  that contacts the negative electrode power line  24   n.  Both the positive electrode power reception unit  36   p  and the negative electrode power reception unit  36   n  are rolling wheels. 
         [0038]    For the sake of convenience, the respective constituent elements of the electric vehicle  10  shown in  FIGS. 1A, 1B, and 1C  are depicted as structural components according to a first example, although the electrical circuitry functions thereof also are the same in the later-described examples. 
         [0039]    In  FIG. 2 , there is shown a front cross-sectional configuration with partial omission of the power line retaining part  14  according to the first example. 
         [0040]    In  FIG. 3 , there is shown a front configuration with partial omission of the charging head  34  according to the first example. 
         [0041]    In  FIG. 4 , there is shown a plan configuration with partial omission of the charging arm  18  according to the first example. 
         [0042]    In  FIG. 5 , there is shown in perspective a configuration showing a contact condition of the charging arm  18  with the power lines  24  that are retained in the power line retaining part  14  in the contact charging system  12  according to the first embodiment. 
         [0043]    In  FIG. 6 , there is shown a front configuration showing a contact condition of the charging arm  18  with the power lines  24  that are retained in the power line retaining part  14  in the contact charging system  12  according to the first embodiment. 
         [0044]    Below, with reference to  FIGS. 1A, 1B, 1C, and 2 through 6 , the power line retaining part  14  according to the first example, the charging arm  18  according to the first, example, and the contact charging system  12  according to the first embodiment, which is equipped with the power line retaining part  14  and the charging arm  18 , will be described in detail. 
         [0045]    As shown in  FIGS. 1A and 4 , the charging arm  18  is constituted from the charging head  34 , a substantially L-shaped bracket  53  to which the charging head  34  is attached, and a slider crank mechanism  30  that, moves (rotates) the charging head  34  along the directions (q 1 , q 2 ) of the arrow q through the bracket  53 . 
         [0046]    The slider crank mechanism  30  is constituted from, an arm member  19  that extends between the bracket  53  and a pin  32  (shaft) that is disposed on the vehicle body of the electric vehicle  10 , a spring damper  39   a,  one end of which is attached rotatably to the middle of the arm member IS and the other end of which is attached rotatably to an actuator  38  that slides on a slide rail  37  in the directions of the arrow p, and a spring damper  39   b,  one end of which is fixed to the vehicle body and the other end of which is fixed to the actuator  38 . 
         [0047]    The actuator  38  is biased so as to move on the slide rail  37  in the direction of the arrow p 1 , whereby the arm member  19  is moved in the direction of the arrow q 1  about the center of rotation of the pin  32  through the spring damper  39   a,  which functions as a lever that swings within a limited range, and the power reception unit  36  of the charging head  34  is urged by the spring dampers  39   a,    39   b  into a state of contact with the power lines  24 . 
         [0048]    In this manner, the charging arm  18  is extended out (deployed or tilted) toward the side of the power supplying device  26  from the side portion  10   s  of the electric vehicle  10 . More specifically, the charging arm  18  is extended in a lateral outward direction of the vehicle body  11 . 
         [0049]    On the other hand, by urging the actuator  38  on the slide rail  37  in the direction of the arrow p 2 , the arm member  19  is moved in the direction of the arrow q 2 , and the charging head  34  is returned to the home position of the vehicle body  11 . 
         [0050]    The charging head  34  is attached on one end of the bracket  53  to a head main body  41  through an attachment member (see  FIG. 3 ). The head main body  41  is generally covered by a casing  52  made of an insulating material, with the exception of the electrical connecting portions of the power reception unit  36 . 
         [0051]    As discussed above, the power supplying device  26  includes the power line retaining part  14 , and a bottom portion of the power line retaining part  14  is fixed to a bottom portion  60   d  of a channel-shaped induction recess  60  (see  FIG. 6 ) made of a non-conducting material, and is fixed to the guard post  20  through the bottom portion  60   d  of the induction recess  60  (see  FIG. 1C ). 
         [0052]    In addition to the bottom portion  60   d  thereof, the induction recess  60  is constituted from, guide members  60   a,    60   b,  and  60   c,  The upper and lower guide members  60   c  extend in a horizontal direction toward the side of the travel path  70  (road) from upper and lower ends of the bottom portion  60   d.  The vertical interval between the upper and lower guide members  60   c  is formed by an interval having a redundancy with respect to the outer diameter of a casing  35  (see  FIG. 6 ) of the charging head  34 . The upper and lower guide members  60   c  are connected contiguously with the upper and lower guide members  60   b  that extend further in the horizontal direction. The vertical interval between the upper and lower guide members  60   b  is narrowed so as to be smaller than the outer shape of the casing  35  of the charging head  34 . The upper and lower guide members  60   b  are connected contiguously with the upper and lower guide members  60   a,  which widen in upper and lower directions UL. The interval of the open ends of the guide members  60   a  is set to an interval whereby the charging head  34  can be guided into the interior of the induction recess  60 , even if the charging head  34  swings upwardly and downwardly in the directions UL when the charging arm  18  is extended. 
         [0053]    On the front side of the power line retaining part  14 , there is provided a V-shaped groove  23  that opens in upper and lower directions UL of the side portion  10   s  of the electric vehicle  10 , and is formed to extend in the running directions RD of the electric vehicle  10 . 
         [0054]    A rear surface of the positive electrode power line  24   p  from among the power lines  24  is fixed to one inner surface of the V-shaped groove  23 , and a rear surface of the negative electrode power line  24   n  from among the power lines  24  is fixed to another inner surface of the V-shaped groove  23 . The positive electrode power line  24   p  and the negative electrode power line  24   n  are fixed by portions thereof being embedded in the power line retaining part  14  at positions to maintain an insulation distance mutually therebetween. Sides of the positive electrode power line  24   p  and the negative electrode power line  24   n  that come into contact with the charging head  34  are in the form of a V-shape. 
         [0055]    On the other hand, the charging head  34  is equipped with the power reception unit  36  having at upper and lower locations thereof the positive electrode power reception unit (positive electrode roller)  36   p  and the negative electrode power reception unit (negative electrode roller)  36   n,  both of which are roiling wheels (rotating rollers), respectively. The positive electrode power reception unit  36   p  and the negative electrode power reception unit  36   n  are formed in the shape of truncated cones, respective bottom surfaces of which vertically face one another, and which are symmetrical with respect to the axis of the charging head  34  (arm member  19 ). More specifically, the contact portions thereof are formed in the shape of wedges that make line contact with the V-shaped groove  23 . 
         [0056]    The power reception unit  36  is engaged with bearings  40 ,  42  (see  FIG. 3 ) of the head main body  41 . On a rear end of the head main body  41 , there are provided, respectively, a vehicle widthwise direction WD suspension  48  constituted by a spring  44 , and an upper and lower direction UL suspension  50  constituted by springs  46   a,    46   b.    
         [0057]    The charging head  34  is fixed by the bracket  53  that is formed on the other end of the arm member  19  through an attachment member  54  that constitutes part of the suspension  50  (see  FIG. 4 ). 
         [0058]    In the contact charging system  12  according to the first embodiment, which is equipped with the charging arm  18  according to the first example and the power supplying device  26  according to the first example that are constructed basically as described above, when the electric vehicle  10  during traveling thereof reaches a position in the vicinity of the power supplying device  26 , the charging arm  18  is urged outwardly in the vehicle widthwise direction WD, and the charging head  34  is guided through the induction recess  60  to the power lines  24 , whereupon as shown in  FIGS. 1C, 5, and 6 , the charging arm  18  and the power supplying device  26  are connected together electrically in a state of contact. 
         [0059]    In this manner, the charging arm  18 , on which the positive electrode power reception unit  36   p  and the negative electrode power reception unit  36   n  are provided above and below on the distal end thereof, is extended out in a lateral or sideways direction of the vehicle body  11 , and by being placed in contact with the power lines  24  that are disposed along the running directions RD of the travel path  70 , the electrical storage device  100  for driving, which is mounted in the electric vehicle  10 , can be charged during traveling. 
         [0060]    More specifically, a configuration is provided in which the positive electrode power reception unit  36   p  of the charging arm  18  and the positive electrode power line  24   p  of the power supplying device  26 , and the negative electrode power reception unit  36   n  of the charging arm  18  and the negative electrode power line  24   n  of the power supplying device  26 , wherein the positive electrode power line  24   p  is fixed to one inner surface and the negative electrode power line  24   n  is fixed to another inner surface of the V-shaped groove  23  that faces toward the side portion  10   s  of the electric vehicle  10  and is formed to open in upper and lower directions DL of the electric vehicle  10  and to extend along the running directions RD of the electric vehicle  10 , are brought into contact simultaneously, and the electrical storage device  100  for driving of the electric vehicle  10  is charged. Therefore, even if the charging arm  18  swings or rocks in upper and lower directions DL due to road conditions of the travel path  70  or braking operations or the like, the charging head  34  that defines the distal end part of the charging arm  18  is retained inside the V-shaped groove  23  under the action of the suspension  50 , etc., and contact is prevented from not being secured. 
         [0061]    Further, because the positive electrode power line  24   p  and the negative electrode power line  24   n  are fixed above and below on inner surfaces of the V-shaped groove  23 , both the power supplying device  26  and the charging arm  18  can be made smaller in scale, and as a result, it is possible for the contact charging system  12  as a whole to be made smaller in scale. 
         [0062]    Moreover, as shown in  FIG. 1B , springs also are interposed in upper and lower directions UL on the pin  32  (shaft), whereby the charging arm  18  functions as a suspension in the upper and lower directions UL. 
         [0063]    Below, descriptions will be given concerning second through fourth embodiments. In the drawings to be referred to below, the same features or corresponding features to those shown in  FIGS. 1 through 6  are denoted by the same reference numerals, or by the reference numerals in which hundredth place digits have been added to the same reference numerals, and detailed descriptions of such features are omitted. Further, since the slider crank mechanism  30 , by which the charging arm  18  extends out laterally or is accommodated on the side of the vehicle body, utilizes the same structure as that shown in  FIG. 1A , detailed description thereof is omitted. 
       Second Embodiment 
       [0064]    In  FIGS. 7 and 8 , there is shown a state of engagement (contact condition) of a charging head  134  according to a second example that constitutes a charging arm  118  according to the second example with power lines  124  that are retained in a power line retaining part  114  according to the second example. The power line retaining part  114  and the charging arm  118  are included in a contact charging system  112  according to the second embodiment. 
         [0065]    The charging head  134  is equipped with a power reception unit  136  made up from a positive electrode power reception unit  136   p  and a negative electrode power reception unit  136   n  having halves of truncated conical shapes, which are embedded with the exception of front surfaces thereof by way of resin molding in a resin material head main body  141 . The positive electrode power reception unit  136   p  and the negative electrode power reception unit  136   n  do not undergo rolling, unlike the positive electrode power reception unit  36   p  and the negative electrode power reception unit  36   n  of the charging head  34  shown in  FIG. 6 . Thus, they can also be considered as the configuration in the form of sliding plate-like shapes. 
         [0066]    A rolling wheel  74  is attached to a bearing  72  on the distal end of the charging head  134 . The rolling wheel  74  is adapted to roll in the running directions RD along a surface of the power line retaining part  114 , in which a groove-shaped bottom portion of a V-shaped groove  123  is in the form of a U-shaped groove. 
         [0067]    In the power line retaining part  114 , on one inner-surface of the V-shaped groove  123 , there is fitted a rear surface side projection of a positive electrode power line  124   p  having a gourd shape in cross section (a shape generally in the form of an oval with a constricted or narrowed center portion), and on the other inner surface thereof, there is fitted a rear surface side projection of a negative electrode power line  124   n.  The front sides of the positive electrode power line  124   p  and the negative electrode power line  124   n  are formed with semicircular shapes in cross section (i.e., with a rounded bar shape with respect to the running directions RD). 
         [0068]    While the rolling wheel  74  of the charging arm  118  rolls along the U-shaped groove of the groove-shaped bottom portion of the V-shaped groove  123 , the positive electrode power line  124   p  of the power line retaining part  114  and the positive electrode power reception unit  136   p  of the charging head  134  undergo sliding contact by way of point contact, and together therewith, the negative electrode power line  124   n  of the power line retaining part  114  and the negative electrode power reception unit  136   n  of the charging head  134  undergo sliding contact by way of point contact, whereby the electrical storage device  100  for driving of the electric vehicle  10  is charged from a power supplying device  126  through the power lines  124  and the charging arm  118 . 
       Third Embodiment 
       [0069]    In  FIGS. 9 and 10 , there is shown a state of engagement (contact condition) of a charging head  234  according to a third example that constitutes a charging arm  218  according to the third example with the power lines  24  that are retained in the power line retaining part  14  according to the first example. The power line retaining part  14  and the charging arm  218  are included in a contact charging system  212  according to the third embodiment. The distal end of the charging head  234  opens expansively in a reverse V-shape, and power reception units  236  made up from a positive electrode power reception unit  236   p  and a negative electrode power reception unit  236   n,  which are cylindrically shaped rolling wheels, are attached to retaining members  238   a,    238   b  of the reverse V-shape. By the positive electrode power reception unit  236   p  and the negative electrode power reception unit  236   n  sliding in line contact while rolling respectively on the positive electrode power line  24   p  and the negative electrode power line  24   n,  the electrical storage device  100  for driving of the electric vehicle  10  is charged from the power supplying device  26  through the charging head  234 . 
         [0070]      FIGS. 11 and 12  show a contact condition of a charging head  234 ′ according to a modification of the third example with the power lines  24  that are retained in the power line retaining part  14  according to the first example. The power line retaining part  14  and the charging head  234 ′ are included in the contact charging system  212 ′ according to a modification of the third embodiment. The charging head  234 ′ is in the form of a reverse V-shape, and upper and lower retaining members  238   a ′,  238   b ′ thereof are offset with respect to the running directions RD. 
         [0071]    A power reception unit  236 ′ made up from a positive electrode power reception unit  236   p ′ and a negative electrode power reception unit  236   n ′, which are cylindrically shaped rolling wheels, are attached to the offset upper and lower retaining members  238   a ′,  238   b ′. By the positive electrode power reception unit  236   p ′ and the negative electrode power reception unit  236   n ′ sliding in line contact while rolling respectively on the positive electrode power line  24   p  and the negative electrode power line  24   n,  the electrical storage device  100  for driving of the electric vehicle  10  is charged from the power supplying device  26  through the charging head  234 ′. 
         [0072]    Because the positive electrode power reception unit  236   p ′ and the negative electrode power reception unit  236   n ′ are attached in an offset manner in forward and rearward directions of the running directions RD, compared with the charging head  234  of the example of  FIGS. 9 and 10 , the pitching behavior of the charging head  234 ′ in the direction of movement (the running directions RD of the electric vehicle  10 ) of the charging head  234 ′ is stabilized, 
       Fourth Embodiment 
       [0073]    In  FIGS. 13, 14, and 15 , there is shown a contact condition of a charging head  334  according to a fourth example that constitutes a charging arm  318  according to a fourth example with the power lines  124  that are retained in the power line retaining part  114  according to the second example. The power line retaining part  114  and the charging arm  318  are included in a contact charging system  312  according to a fourth embodiment. 
         [0074]    The charging head  334  includes a base section  348  shaped in the form of a triangular prism. An attachment member  354  is mounted on one side surface of the base section  348 , and rolling wheels  352  are attached through attachment members  350  to ends on upper and lower surfaces (in directions perpendicular to the sheet in  FIG. 14 ) of the base section  348 . 
         [0075]    Further, attachment plates  358  to which a power reception unit  336  is attached are disposed in parallel on both remaining side surfaces of the base section  348 . The power reception unit  336  includes a positive electrode power reception unit  336   p  and a negative electrode power reception unit  336   n,  which are biased respectively through springs  356  toward a side of the positive electrode power line  124   p  and toward a side of the negative electrode power line  124   n.    
         [0076]    The attachment plates  358  are biased by the springs  356  toward the sides of the power lines  124  about respective supporting shafts disposed between facing surfaces of the attachment members  350  on the sides of the rolling wheels  352 . 
         [0077]    More specifically, the attachment plates  358  are urged in the directions of the arrows r, together with movement thereof being regulated by spring mechanisms  95  made up from the springs  356 , pins  94 , regulating members  93 , and pins  92 . 
         [0078]    In the charging head  334  according to the fourth example, while the rolling wheels  352  roll along a U-shaped groove of the V-shaped groove  123  in which the groove-shaped bottom portion thereof is in the form of a U-shaped groove, the positive electrode power reception unit  336   p  is kept in contact by a compression force of the spring  356  with respect to the positive electrode power line  124   p,  and together therewith, the negative electrode power reception unit  336   n  is kept in contact by a compression force of the spring  356  with respect to the negative electrode power line  124   n,  whereby the electrical storage device  100  for driving of the electric vehicle  10  is charged from the power supplying device  126  through the charging head  234 . 
       SUMMARY OF EMBODIMENTS 
       [0079]    As described above, according to the aforementioned embodiments, for example as shown in  FIGS. 1A, 1B, 1C, and 6 , a configuration is provided comprising the power supplying device  26 , which includes the power line retaining part  14  in which the V-shaped groove  23  is provided that faces toward the side portion  10   s  of the electric vehicle  10  and is formed to open in upper and lower directions DL of the electric vehicle  10  and to extend in the running directions ED of the electric vehicle  10 , and the positive electrode power line  24   p  on one inner surface and the negative electrode power line  24   n  on another inner surface of the V-shaped groove  23  that makes up the power line retaining part  14  are fixed to the power line retaining part  14  respectively along the running directions RD and at positions to maintain an insulation distance mutually therebetween. In addition, the charging arm  18 , which is accommodated in the side portion  10   s  of the electric vehicle  10  and includes the positive electrode power reception unit  36   p  and the negative electrode power reception unit  36   n,  which are provided on a distal end thereof and are disposed so as to face the corresponding positive electrode power line  24   p  and the negative electrode power line  24   n  of the power supplying device  26 , is made to extend out in a vehicle widthwise direction WD, and to bring into contact simultaneously the positive electrode power line  24   p  of the power supplying device  26  and the positive electrode power reception unit  36   p  of the charging arm  18 , and the negative electrode power line  24   n  of the power supplying device  26  and the negative electrode power reception unit  36   n  of the charging arm  18 , so as to charge the electrical storage device  100  for driving of the electric vehicle  10 . Therefore, even if the charging arm  18  swings or rocks in upper and lower directions UL due to road conditions or braking operations or the like, the charging head  34  that defines the distal end part of the charging arm  18  is retained inside the V-shaped groove  23 , and contact is prevented from not being secured. 
         [0080]    Further, because the positive electrode power line  24   p  and the negative electrode power line  24   n  are fixed above and below on inner surfaces of the V-shaped groove  23 , both the power supplying device  26  and the charging arm  18  can be made smaller in scale, and as a result, it is possible for the contact charging system  12  as a whole to be made; smaller in scale. 
         [0081]    The present invention is not limited to the above-described embodiments, and it goes without saying that various configurations could be adopted therein, based on the content disclosed in the present specification.