Abstract:
An electric vehicle charges an electricity storage device by allowing the power receiving portions of a charging arm to make contact with an aerial wire. In the electric vehicle, the charging arm is equipped with an arm portion that is expanded from a side portion of the electric vehicle toward the outside of the vehicle width by rotationally moving about a rotationally moving shaft. The power receiving portions are provided on a charging head positioned at the top of the arm portion. The charging head is set so as to face the aerial wire in such a direction that the longitudinal direction of the charging head becomes orthogonal to the aerial wire when the arm portion is expanded to a predetermined rotational movement angle. The arm portion is expanded up to a first rotational movement angle larger than the predetermined rotational movement angle.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an electric vehicle that charges an energy storage device of the electric vehicle by bringing a charging head into contact with power lines through which electrical power is supplied during traveling. 
       BACKGROUND ART 
       [0002]    In Japanese Laid-Open Patent Publication No. 2013-233037, charging of an energy storage device of an electric vehicle is disclosed in which, during traveling of the electric vehicle, power receiving elements (rollers) of a charging head disposed on a distal end of an arm portion of the electric vehicle are brought into contact while undergoing rotation with power lines to which electric power is supplied. 
       SUMMARY OF INVENTION 
       [0003]    Provisionally, in the case of a configuration in which a longitudinal direction of the charging head is arranged perpendicularly to the power lines when the arm portion is open, if the distance between the electric vehicle and the power lines becomes shorter, the arm portion is returned toward the side of the electric vehicle in a state in which the charging head is in contact with the power lines. For this reason, as the distance between the electric vehicle and the power lines becomes shorter, the angle defined by the longitudinal direction of the charging head and the power lines gradually becomes smaller. Consequently portions apart from the power receiving elements of the charging head interfere with the power lines, and it becomes impossible for the charging member to remain in contact with the power lines. 
         [0004]    The present invention has the object of providing an electric vehicle that enables power receiving elements and power lines to stably remain in contact with each other, even in the case that the angle formed by a charging head and the power lines vary due to a variation in the distance between the electric vehicle and the power lines. 
         [0005]    The present invention is characterized by an electric vehicle that charges an energy storage device configured to drive the electric vehicle, by bringing power receiving elements of a charging arm into contact with power lines, which are disposed along a travel path of the electric vehicle together with facing toward a side portion of the electric vehicle, and to which electrical power is supplied, wherein the charging arm comprises an arm portion configured to be deployed, during charging, from the side portion of the electric vehicle toward an outer side in a vehicle transverse direction by rotating the charging arm about a rotary shaft, the power receiving elements are disposed in a charging head configured to be positioned on a distal end of the arm portion, the charging head is set so as to face toward the power lines at an orientation in which a longitudinal direction of the charging head is perpendicular to the power lines in a case where the arm portion is deployed at a predetermined angle of rotation, and the arm portion is deployed up to a first angle of rotation, which is greater than the predetermined angle of rotation. 
         [0006]    According to the present invention, in the electric vehicle, the charging arm includes an actuator configured to slide along a slide rail, and a spring damper comprising one end attached rotatably to the arm portion, and another end attached rotatably to the actuator, and the spring damper biases the arm portion in a direction to deploy the arm portion outwardly in the vehicle transverse direction. 
         [0007]    According to the present invention, in the electric vehicle, the slide rail is disposed in a longitudinal direction of the electric vehicle. 
         [0008]    According to the present invention, in the electric vehicle, the charging head is attached to a distal end of the arm portion through a bracket, to define a predetermined angle between the longitudinal direction of the charging head and a direction in which the arm portion extends. 
         [0009]    According to the present invention, since the arm portion is deployed to the first angle of rotation that is greater than the predetermined angle of rotation, even in the case that the distance between the electric vehicle and the power lines is varied by the power receiving elements contacting the power lines and the arm portion being returned to the side of the electric vehicle, the power receiving elements and the power lines can stably be kept in contact with each other. 
         [0010]    According to the present invention, since the spring damper biases the arm portion in a direction to deploy the arm portion outwardly in the vehicle transverse direction, when the arm portion is brought into contact with the power lines and returned to the side of the electric vehicle, the power receiving elements are pressed against the power lines by the biasing force of the spring damper. Consequently, the contact pressure between the power receiving elements and the power lines can be maintained, and electrical power from the power lines can be supplied in a stable manner to the energy storage device. 
         [0011]    According to the present invention, since the charging head is attached to the distal end of the arm portion through a bracket, in such a manner that the longitudinal direction of the charging head and a direction in which the arm portion extends define a predetermined angle, at a time that the arm portion is deployed to the predetermined angle, the charging head can simply be attached to the distal end of the arm portion so that the longitudinal direction thereof faces toward the power lines at a direction perpendicular with respect to the power lines. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1  is a view showing a schematic overall configuration of a contact type charging system when an electric vehicle according to an embodiment of the invention is viewed from an upper side; 
           [0013]      FIG. 2  is a view showing a schematic overall configuration of the contact type charging system when an electric vehicle according to an embodiment of the invention is viewed from a front side; 
           [0014]      FIG. 3  is a view showing an installation structure for the power lines shown in  FIG. 1 ; 
           [0015]      FIG. 4  is a cross-sectional view taken along line IV-IV of  FIG. 3 ; 
           [0016]      FIG. 5  is a view showing an example of an electrical power supplying device provided on a travel path; 
           [0017]      FIG. 6  is a perspective view of a charging head shown in  FIG. 1 ; 
           [0018]      FIG. 7  is a side view of the charging head shown in  FIG. 1 ; 
           [0019]      FIG. 8  is a plan view of the charging head shown in  FIG. 1 ; 
           [0020]      FIG. 9  is a view showing a state of contact between the charging head and the power lines; 
           [0021]      FIG. 10  is a schematic view of a charging arm shown in  FIG. 1 ; 
           [0022]      FIG. 11  is a view showing a relationship between an angle of rotation of the charging arm, and a distance to the power lines from a side portion on a driver&#39;s seat side of the electric vehicle; 
           [0023]      FIG. 12  is a view showing a charging head according to a modification; 
           [0024]      FIG. 13  is a view showing a main body portion illustrated in  FIG. 12 ; and 
           [0025]      FIG. 14  is a view showing an example in which an accommodating section is disposed on a lower part of the main body portion according to a modification. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0026]    A preferred embodiment of an electric vehicle according to the present embodiment will be described in detail below with reference to the accompanying drawings. 
         [0027]      FIG. 1  shows a schematic overall configuration of a contact type charging system  12  when an electric vehicle  10  is viewed from an upper side, and  FIG. 2  shows a schematic overall configuration of the contact type charging system  12  when the electric vehicle  10  is viewed from a front side. The electric vehicle  10  is a vehicle in which there are mounted an electric motor  14  serving as a drive source, and a driving energy storage device  16  for supplying electrical power to the electric motor  14 , and corresponds, for example, to an electric automobile, a hybrid vehicle equipped with an internal combustion engine, and a fuel cell vehicle equipped with a fuel cell. The front and rear, left and right, and upper and lower directions will be described in accordance with the directions of the arrows shown in  FIGS. 1 and 2 . 
         [0028]    The contact type charging system  12  is constituted at least from power lines  20  made of a conductive material to which electrical power is supplied, and the electric vehicle  10 , which is equipped with a charging arm  22  capable of being placed in contact with the power lines  20 . The charging arm  22  is provided on a side portion  10   s  on the side of a driver&#39;s seat  18  on the right side of the electric vehicle  10 , and is disposed between the front wheels WF and the rear wheels WR. In countries in which roads are for right side traveling, the driver&#39;s seat  18  generally is located on the left side of the electric vehicle  10 , and therefore, the charging arm  22  is disposed on a side portion on the left side of the electric vehicle  10 . 
         [0029]    The power lines  20  are arranged along a travel path (road)  24  on which the electric vehicle  10  travels, and are arranged in facing relation to the side portion  10   s  on the driver&#39;s seat  18  side of the electric vehicle  10 . The power lines  20  are arranged on the side of a central line of the travel path  24 . In the case of roads on which there are plural oblique lines on one side (for example, in the case of roads on which there are two lanes or three lanes on one side), the power lines  20  are arranged in the vicinity of the central line and are not disposed respectively in each of the lanes. Further, in the case of a road in which there is a central dividing median, the power lines  20  may be arranged on the median. 
         [0030]    The power lines  20  may be disposed at the length of a specified section. The length of the specified section, for example, may be set to a length that is capable of charging the electric vehicle  10 , so as to be capable of traveling from a position where certain power lines  20  are disposed to the position where next power lines  20  are disposed. 
         [0031]    While traveling along the power lines  20  on a travel path  24  on which the power lines  20  are arranged, a charging head  26  provided on the distal end of the charging arm  22  of the electric vehicle  10  is extended outwardly in the vehicle transverse direction, and the energy storage device  16  is charged by the charging head  26  coming into contact with the power lines  20 . 
         [0032]      FIG. 3  is a view showing an installation structure for the power lines  20 , and  FIG. 4  is a cross-sectional view taken along line IV-IV of  FIG. 3 . The power lines  20  are retained by a power line retaining unit  30  made of an insulating material, and the power line retaining unit  30  is supported from a rear side thereof by guard posts  32  disposed at predetermined intervals along the travel path  24 . The guard posts  32  support the power line retaining unit  30  so that the height thereof enables the power lines  20  to come into contact with the distal end of the charging arm  22 . The power line retaining unit  30  maintains the power lines  20  along the lengthwise direction of the power lines  20 . 
         [0033]    A power source  34  supplies electrical power to the power lines  20 . The power lines  20  include a positive electrode side power line  20   p  made of a conductive material, and a negative electrode side power line  20   n  made of a conductive material and arranged below the positive electrode side power line  20   p.  A first voltage, which is a high DC voltage, is imposed on the positive electrode side power line  20   p  from the power source  34 , and a second voltage, which is a low DC voltage (reference voltage) of a lower direct current than the first voltage, is imposed on the negative electrode side power line  20   n  from the power source  34 . A front side of the power line retaining unit  30  is shaped in the form of a V-shaped groove  36  so as to open in the vertical direction. The positive electrode side power line  20   p  is embedded therein so that a front surface thereof is exposed on an upper surface  36   a  of the V-shaped groove  36 , and the negative electrode side power line  20   n  is embedded therein so that a front surface thereof is exposed on a lower surface  36   b  of the V-shaped groove  36 . The voltage imposed on the power lines  20  ( 20   p,    20   n ) may also be an AC voltage. The power lines  20 , the power line retaining unit  30 , and the power source  34  make up an electrical power supplying device  38  that supplies electrical power to the electric vehicle  10 . 
         [0034]      FIG. 5  is a view showing an example of the electrical power supplying device  38  disposed on a travel path  24 . In  FIG. 5 , a one-side three lane travel path  24 , or stated otherwise, a six lane road is illustrated, in which a central median  39  serving as a central line is disposed on the road. One of the travel paths  24  is a travel path  24   a  along which the electric vehicle  10  travels, and the other of the travel paths  24  is a travel path  24   b  along which an oncoming vehicle travels. The central median  39 , which serves as a central line, serves to partition the travel path  24   a  and the travel path  24   b.    
         [0035]    As shown in  FIG. 5 , power line retaining units  30  that retain the power lines  20  are disposed respectively corresponding to the travel paths  24   a,    24   b.  The power line retaining unit  30  that is disposed corresponding to the travel path  24   a  is disposed on the travel path  24   b  side of the travel path  24   a,  whereas the power line retaining unit  30  that is disposed corresponding to the travel path  24   b  is disposed on the travel path  24   a  side of the travel path  24   b.  Further, the power source  34  is disposed between the travel path  24   a  and the travel path  24   b.  As shown in  FIG. 5 , the power source  34  is disposed on the central median  39 . Owing thereto, the power source  34  that supplies power to the power lines  20  disposed on the travel paths  24   a,    24   b  can be used in common. Stated otherwise, a single power source  34  supplies electrical power with respect to the power lines  20  of both of the travel paths  24   a,    24   b . Consequently, complexity of the electrical wiring from the power source  34  to the power lines  20  of the travel paths  24   a,    24   b  can be suppressed. 
         [0036]    The power line retaining units  30  that retain the power lines  20  of the travel paths  24   a,    24   b  may also be disposed on the central median  39 . In this case, the power line retaining unit  30  corresponding to the travel path  24   a  is disposed on the side of the travel path  24   a,  whereas the power line retaining unit  30  corresponding to the travel path  24   b  is disposed on the side of the travel path  24   b.    
         [0037]      FIG. 6  is a perspective view of the charging head  26 ,  FIG. 7  is a side view of the charging head  26 , and  FIG. 8  is a plan view of the charging head  26 . The charging head  26  comprises a positive electrode side power receiving element  40   p  in the form of a roller that contacts the positive electrode side power line  20   p  of the power lines  20 , and a negative electrode side power receiving element  40   n  in the form of a roller that contacts the negative electrode side power line  20   n  of the power lines  20 . The positive electrode side power receiving element  40   p  and the negative electrode side power receiving element  40   n  are provided vertically in a pair. Power receiving elements  40  ( 40   p,    40   n ) are disposed on a distal end side of the charging head  26 . The power receiving elements  40   p,    40   n  are formed from a conductive material. As shown in  FIG. 7 , the power receiving elements  40   p,    40   n  are each of the same structure and shape, and include a first roller member  42   a  having a substantially frustoconical shape, and a second roller member  42   b  having a substantially cylindrical shape and disposed on a bottom surface side of the first roller member  42   a.  The first roller member  42   a  and the second roller member  42   b  are formed integrally with centers thereof arranged on the same axis (coaxially). 
         [0038]    The cylindrically shaped second roller members  42   b  have an outer circumferential surface of a first radius r 1 , and the outer circumferential surface of the first roller members  42   a  include radii that are larger than the first radius r 1 . Owing thereto, the first roller members  42   a  can be placed in contact with respect to the power lines  20 , and the circumferential velocity of the outer circumferential surface of the second roller members  42   b  is smaller in comparison with that of the first roller members  42   a.  More specifically, the first roller member  42   a  is substantially in the form of a truncated cone, the bottom surface of which is formed with a circular second radius r 2  that is greater than the first radius r 1 , and the upper surface of which is formed with a circular third radius r 3  that is smaller than the second radius r 2 . Stated otherwise, the outer circumferential surface of the first roller member  42   a  is formed by the second radius r 2  and the third radius r 3 . The third radius r 3  may be either smaller or larger than the first radius r 1 . 
         [0039]    The power receiving elements  40   p,    40   n  are mounted on the charging head  26  by being separated in a vertically symmetrical manner, such that the second roller members  42   b  face toward one another mutually. It is possible for the positive electrode side power line  20   p  and the negative electrode side power line  20   n  provided in the V-shaped groove  36  to be contacted by the first roller members  42   a  of the positive electrode side power receiving element  40   p  and the negative electrode side power receiving element  40   n.  The first roller members  42   a  may also be formed in a cylindrical columnar shape of the second radius r 2 . In this case, there is no need for the V-shaped groove  36  to be provided in the power line retaining unit  30 . 
         [0040]    The power receiving elements  40   p,    40   n  are axially supported rotatably by a rotary support member  46  that is mounted on a main body portion  44  of the charging head  26 . The rotary support member  46  includes a first support member  46   a  that rotatably supports the power receiving element  40   p,  and a second support member  46   b  that rotatably supports the power receiving element  40   n.  More specifically, the first support member  46   a  includes a support shaft (central shaft)  48   a  that extends in a vertical direction supporting the power receiving element  40   p,  and the power receiving element  40   p  is attached rotatably to the support shaft  48   a  through a bearing  50   a . Similarly, the second support member  46   b  includes a support shaft (central shaft)  48   b  that extends in a vertical direction supporting the power receiving element  40   n,  and the power receiving element  40   n  is attached rotatably to the support shaft  48   b  through a bearing  50   b.  The first support member  46   a  and the second support member  46   b  have the same shape, and are attached in a vertically symmetrical manner to the main body portion  44 . 
         [0041]    The main body portion  44  includes a base section  52  having a disk-shaped flange  52   a,  and a partition plate  54  disposed contiguously toward the distal end side of the charging head  26  from a side surface of the flange  52   a,  and which vertically partitions the power receiving element  40   p  and the power receiving element  40   n.  The first support member  46   a  is attached upwardly of the partition plate  54 , and the second support member  46   b  is attached downwardly of the partition plate  54 . Distal end parts of the power receiving elements  40   p,    40   n  (distal ends of the first roller members  42   a ) project out more toward the distal end side than the partition plate  54 . Consequently, the distal end parts of the power receiving elements  40   p,    40   n  can be placed in contact with the power lines  20 . Further, as shown in  FIG. 6 , the rearward side of the main body portion  44  and the power receiving elements  40   p,    40   n  are covered by a cover  56 . 
         [0042]    A conductive brush (contact conductor)  58   a  that contacts the second roller member  42   b  of the power receiving element  40   p  is disposed slidably along a longitudinal direction of the charging head  26  (the directions of the arrow x in  FIGS. 7 and 8 ) in the interior of the first support member  46   a.  A contact surface of the brush  58   a  in contact with the second roller member  42   b  includes an arcuate shape in accordance with the shape of the second roller member  42   b.  In addition, two conductive bus bars  60   a,    60   a  extend through a through hole  62   a  formed in the interior of the base section  52  and a through hole  64   a  formed in the interior of the first support member  46   a , and are connected electrically to the brush  58   a.  The two bus bars  60   a,    60   a  are connected to the brush  58   a  over a predetermined interval in the horizontal direction. Other ends of the bus bars  60   a,    60   a  are fixed in a non-movable state, and are connected electrically to the energy storage device  16  of the electric vehicle  10  through electrical cables  86   a  disposed in the interior of an arm portion  86  (see  FIG. 10 ) of the charging arm  22 . The through hole  62   a  communicates with the through hole  64   a  by being branched into two in a horizontal direction in the interior of the flange  52   a  of the base section  52 . An opening  66   a  of the through hole  64   a  has a size that covers two openings  68   a ,  68   a  of the through hole  62   a  that is formed in the flange  52   a.    
         [0043]    Similarly, a conductive brush (contact conductor)  58   b  that contacts the second roller member  42   b  of the power receiving element  40   n  is disposed slidably along a longitudinal direction of the charging head  26  in the interior of the second support member  46   b.  A contact surface of the brush  58   b  in contact with the second roller member  42   b  includes an arcuate shape in accordance with the shape of the second roller member  42   b.  In addition, two conductive bus bars  60   b,    60   b  extend through a through hole  62   b  formed in the interior of the base section  52  and a through hole  64   b  formed in the interior of the second support member  46   b,  and are connected to the brush  58   b.  The two bus bars  60   b,    60   b  are connected to the brush  58   b  over a predetermined interval in the horizontal direction. Other ends of the bus bars  60   b,    60   b  are fixed in a non-movable state, and are connected electrically to the energy storage device  16  of the electric vehicle  10  through electrical cables  86   b  disposed in the interior of the arm portion  86  (see  FIG. 10 ) of the charging arm  22 . The through hole  62   b  communicates with the through hole  64   b  by being branched into two in a horizontal direction in the interior of the flange  52   a  of the base section  52 . An opening  66   b  of the through hole  64   b  has a size that covers two openings  68   b ,  68   b  of the through hole  62   b  that is formed in the flange  52   a.    
         [0044]    As shown in  FIG. 9 , while the electric vehicle  10  is traveling, since charging is carried out by the power receiving elements  40   p,    40   n  of the charging head  26  being placed in contact with the power lines  20 , the power receiving elements  40   p,    40   n  of the charging head  26  contact the brushes  58   a,    58   b  while undergoing rotation. Consequently, contact friction is generated between the brushes  58   a,    58   b  and the power receiving elements  40   p,    40   n . For this reason, when the second roller members  42   b  of the power receiving elements  40   p,    40   n  and/or the brushes  58   a ,  58   b  gradually are abraded and subjected to wear over time, a condition of non-contact occurs between the brushes  58   a ,  58   b  and the second roller members  42   b  of the power receiving elements  40   p,    40   n.    
         [0045]    Thus, by spring members (biasing members)  70   a,    70   b  that are disposed inside the through holes  64   a,    64   b,  the brushes  58   a,    58   b  are biased (pressed) in the direction of the arrow x toward the sides of the second roller members  42   b  (toward the distal end side of the charging head  26 ). Owing thereto, even if the power receiving elements  40   p ,  40   n  and/or the brushes  58   a,    58   b  become abraded, due to the spring members  70   a,    70   b,  the brushes  58   a,    58   b  can be pressed against the second roller members  42   b  of the power receiving elements  40   p,    40   n  by sliding (or being moved) toward the distal end side. Consequently, the first voltage can be transmitted reliably to the bus bars  60   a,    60   a  from the positive electrode side power line  20   p  through the positive electrode side power receiving element  40   p,  and the second voltage can be transmitted reliably to the bus bars  60   b,    60   b  from the negative electrode side power line  20   n  through the negative electrode side power receiving element  40   n.    
         [0046]    Further, in the charging head  26 , the bus bars  60   a ,  60   a  at the interior of the through holes  62   a,    64   a,  and the bus bars  60   b,    60   b  at the interior of the through holes  62   b ,  64   b  are retained to a certain degree in a slackened state. Stated otherwise, in comparison with a length of a shortest distance of the bus bars  60   a,    60   b  that interconnects the distal end sides of the electrical cables  86   a,    86   b  and the brushes  58   a,    58   b,  a length of the bus bars  60   a,    60   b  is set to possess a further surplus length, and the surplus length thereof is subjected to slackening in the interior of the through holes  62   a,    64   a  and the through holes  62   b,    64   b . Owing thereto, the bus bars  60   a,    60   b  can be allowed to follow along with the movement of the brushes  58   a,    58   b,  and thus, the brushes  58   a,    58   b  can be moved toward the side of the power receiving elements  40   p,    40   n.    
         [0047]    One end of the spring member  70   a  is mounted on the brush  58   a  between the two bus bars  60   a,    60   a,  and the other end of the spring member  70   a  is mounted on the flange  52   a  between the openings  68   a,    68   a.  Similarly, one end of the spring member  70   b  is mounted on the brush  58   b  between the two bus bars  60   b,    60   b,  and the other end of the spring member  70   b  is mounted on the flange  52   a  between the openings  68   b,    68   b.    
         [0048]    Further, by contact friction between the power lines  20  and the first roller members  42   a  of the power receiving elements  40   p,    40   n  due to rotation of the power receiving elements  40   p,    40   n,  the first roller members  42   a  of the power receiving elements  40   p,    40   n  and/or the power lines  20  gradually are abraded and subjected to wear over time. As a result of such abrasion, wear debris (shavings) from the first roller members  42   a  and/or the power lines  20  are ejected. Further, as discussed previously, by abrasion due to contact friction between the second roller members  42   b  of the power receiving elements  40   p,    40   n  and the brushes  58   a,    58   b,  wear debris (shavings) from the second roller members  42   b  and/or the brushes  58   a,    58   b  are ejected. 
         [0049]    When such wear debris is scattered about, there is a possibility for adverse effects such as insulation defects or the like in peripheral components to occur. Further, it is contemplated that such wear debris generated by rotation of the power receiving element  40   p  may fall downwardly and impart an adverse influence on the power receiving element  40   n.  For example, it is conceivable that an influence will be effected on the contact state between the power lines  20  and the power receiving element  40   n,  or that the power receiving element  40   p  cannot be rotated smoothly, or that an arc may be generated. 
         [0050]    Thus, a recessed part  54   a  is provided, which is recessed a predetermined depth in an upper surface of the partition plate (accommodating section)  54  that is disposed between the power receiving elements  40   p,    40   n.  The recessed part  54   a  is formed around an outer periphery of the partition plate  54 . Since wear debris, which is generated by contact friction between the first roller member  42   a  of the power receiving element  40   p  and the positive electrode side power line  20   p,  is accommodated in the recessed part  54   a,  scattering about of the wear debris that is generated by contact friction between the first roller member  42   a  of the power receiving element  40   p  and the positive electrode side power line  20   p  can be prevented. Accordingly, the occurrence of adverse effects such as insulation defects or the like in peripheral components can be suppressed. 
         [0051]    Further, when the charging head  26  is observed from a vertical direction, the recessed part  54   a  is formed in the partition plate  54  so as to surround the contact position between the power receiving element  40   p  and the brush  58   a . Consequently, since wear debris, which is generated by contact friction between the second roller member  42   b  of the power receiving element  40   p  and the brush  58   a,  is accommodated in the recessed part  54   a,  scattering about of the wear debris that is generated by contact friction between the second roller member  42   b  of the power receiving element  40   p  and the brush  58   a  can be prevented. Accordingly, the occurrence of adverse effects such as insulation defects or the like in peripheral components can be suppressed. 
         [0052]    As shown in  FIG. 10 , the charging arm  22  includes, apart from the charging head  26 , a bracket  80  to which the charging head  26  is attached, and a slider crank mechanism  82  by which the charging head  26  is moved (rotated) through the bracket  80  in the directions of the arrow q (q 1 , q 2 ). 
         [0053]    The slider crank mechanism  82  includes the arm portion  86 , which is deployed horizontally in a vehicle transverse and outward direction by rotating about a rotary shaft  84  provided on the electric vehicle  10 , a slide rail  88 , which is mounted along the longitudinal direction of the vehicle body more on an inner side of the vehicle body of the electric vehicle  10  than the arm portion  86 , an actuator  90  that slides on the slide rail  88  in the directions of the arrow p (p 1 , p 2 ), and a spring damper  92 , one end of which is attached rotatably to the arm portion  86 , and another end of which is attached rotatably to the actuator  90 . The charging head  26  is attached to the distal end side (a side opposite to the rotary shaft  84 ) of the arm portion  86  through the bracket  80 . The spring damper  92  biases the arm portion  86  in a direction to deploy the arm portion  86  outwardly in the vehicle transverse direction. 
         [0054]    When the actuator  90  moves on the slide rail  88  in the direction of the arrow p 1 , the arm portion  86  is rotated about the rotary shaft  84  in the direction of the arrow q 1 , and the charging head  26  is also moved together therewith in the direction of the arrow q 1 . As a result, the arm portion  86  opens horizontally about the rotary shaft  84  from a lateral side of the vehicle body of the electric vehicle  10 , and the charging head  26  moves to the side of the power lines  20 . 
         [0055]    On the other hand, when the actuator  90  moves on the slide rail  88  in the direction of the arrow p 2 , the arm portion  86  is rotated about the rotary shaft  84  in the direction of the arrow q 2 , and the charging head  26  is also moved together therewith in the direction of the arrow q 2 . As a result, a closed state of the arm portion  86  is brought about, and the charging head  26  is housed in the electric vehicle  10 . 
         [0056]    In the present embodiment, the position of the actuator  90  when the charging head  26  is accommodated (the state shown by the two-dot-dashed lines of  FIG. 10 ) is regarded as an initial position d 1 , and in the case that charging is to be carried out, the actuator  90  is moved from the initial position d 1  to a predetermined position d 2  along the direction of the arrow p 1 . Consequently, the arm portion  86  is deployed up to a first angle of rotation θ 1 , and the charging head  26  projects (outwardly of the electric vehicle  10 ) toward the side of the power lines  20  (the state shown by the solid lines of  FIG. 10 ). The angle of rotation refers to an angle from the state in which the arm portion  86  is accommodated. 
         [0057]    As shown in  FIG. 11 , when the arm portion  86  is deployed up to the first angle of rotation θ 1 , the charging head  26  can be placed in contact with the power lines  20 , which are separated a first predetermined distance z 1  from the side portion  10   s  on the side of the driver&#39;s seat  18  of the electric vehicle  10 . Additionally, when the distance to the power lines  20  from the side portion  10   s  on the side of the driver&#39;s seat  18  of the electric vehicle  10  becomes shorter than the first predetermined distance z 1 , the charging head  26  is pressed by the power lines  20 , whereupon the arm portion  86  undergoes rotation in the direction (closing direction) of the arrow q 2  in opposition to the biasing force of the spring damper  92 . Along therewith, the charging head  26  also is moved in the direction of the arrow q 2  (toward the side of the vehicle body). 
         [0058]    However, since it is impossible for the spring damper  92  to be contracted beyond a predetermined length, the range within which the charging head  26  can be moved in the direction of the arrow q 2  is limited. For the sake of convenience, the angle of rotation of the arm portion  86  at the time that the spring damper  92  is contracted maximally will be referred to as a second angle of rotation θ 2 . In other words, during power reception, in accordance with the spring damper  92 , the arm portion  86  can be rotated within the range of the second angle of rotation θ 2  from the first angle of rotation θ 1 . Consequently, the distance between the power lines  20 , which are contacted by the power receiving elements  40   p,    40   n  of the charging head  26  when the arm portion  86  is at the second angle of rotation θ 2 , and the side portion  10   s  on the side of the driver&#39;s seat  18  of the electric vehicle  10  becomes a second predetermined distance z 2  that is shorter than the first predetermined distance z 1 . Moreover, during charging, the angle of rotation of the arm portion  86  does not become smaller than the second angle of rotation θ 2 , and therefore, the distance between the power lines  20  and the side portion  10   s  on the side of the driver&#39;s seat  18  of the electric vehicle  10  (also referred to as a “distance between the electric vehicle  10  and the power lines  20 ) does not become less than the second predetermined distance z 2 . 
         [0059]    Further, when the spring damper  92  has been retracted to a fixed length, by the actuator  90  undergoing movement or the like in the direction of the arrow p 2 , the angle of rotation can be controlled by controlling or interlocking the retraction of the spring damper  92  and movement of the actuator  90 . In this case, the contact pressure between the power lines  20  and the power receiving elements  40   p,    40   n  due to the spring damper  92  can be controlled more finely. Further, even in this case, the rotational range of the arm portion  86  is limited to within a predetermined angular range. 
         [0060]    Since charging of the electric vehicle  10  is carried out during traveling, accompanying the time of traveling, due to vibration and swaying of the electric vehicle  10  or the like, the electric vehicle  10  swings to the left and right, and the distance between the electric vehicle  10  and the power lines  20  becomes both longer and shorter. Further, when the distance between the electric vehicle  10  and the power lines  20  becomes smaller than the first predetermined distance z 1 , a condition occurs in which the power receiving elements  40   p,    40   n  of the charging head  26  are pressed against the power lines  20  by the biasing force of the spring damper  92 . Consequently, when charging is carried out during traveling, by setting the distance between the electric vehicle  10  and the power lines  20  in advance to be shorter than the first predetermined distance z 1 , even if vibration and swaying occurs in the electric vehicle  10 , the contact pressure between the power lines  20  and the power receiving elements  40   p,    40   n  of the charging head  26  can be maintained by the spring damper  92 , and thus they can be allowed to contact one another in a stable manner. 
         [0061]    When charging is carried out, by allowing the electric vehicle  10  to travel in such a manner that the distance between the electric vehicle  10  and the power lines  20  becomes a distance (third predetermined distance z 3 ) exactly in the middle of the first predetermined distance z 1  and the second predetermined distance z 2 , swinging of the electric vehicle  10  to the left and right can be responded to most effectively. The rotational angle of the arm portion  86  when the distance between the electric vehicle  10  and the power lines  20  is at the third predetermined distance z 3 , for the sake of convenience, will be referred to as a third angle of rotation (predetermined angle of rotation) θ 3 . 
         [0062]    According to the present embodiment, it is assumed that the electric vehicle  10  travels in such a manner that the distance between the electric vehicle  10  and the power lines  20  becomes the third predetermined distance z 3 . Therefore, as shown in  FIG. 1 , a guideline  100  for guiding the distance between the electric vehicle  10  and the power lines  20  may be disposed on the travel path  24 . In this case, the guideline  100  also constitutes part of the contact type charging system  12 . 
         [0063]    When the rotational angle of the arm portion  86  is at the third angle of rotation θ 3 , the charging head  26  is attached to the arm portion  86  through the bracket  80 , such that the longitudinal direction of the charging head  26  faces toward the power lines  20  at a direction perpendicular with respect to the power lines  20 . Stated otherwise, the charging head  26  is attached to the distal end of the arm portion  86  through the bracket  80 , in such a manner that the longitudinal direction of the charging head  26  with respect to the longitudinal direction of the arm portion  86  (direction of extension) is bent toward the side of the opening direction of the arm portion  86 . The longitudinal direction of the charging head  26  and the longitudinal direction of the arm portion  86  define a predetermined angle. 
         [0064]    When the rotational angle of the arm portion  86  is at the third angle of rotation θ 3 , an angle α defined by the power lines  20  and the longitudinal direction of the charging head  26  is set to α 3  (α 3 = 90 °). Further, when the rotational angle of the arm portion  86  is at the first angle of rotation θ 1 , the angle α defined by the power lines  20  and the longitudinal direction of the charging head  26  is set to α 1 , and when the rotational angle of the arm portion  86  is at the second angle of rotation θ 2 , the angle α defined by the power lines  20  and the longitudinal direction of the charging head  26  is set to α 2 . In terms of the angle α in the present embodiment, among the angles defined by the power lines  20  and the longitudinal direction of the charging head  26 , a smaller angle is indicated. 
         [0065]    If the charging head  26  is disposed so that the longitudinal direction of the charging head  26  is perpendicular with respect to the power lines  20  when the rotational angle of the arm portion  86  is at the first angle of rotation θ 1 , and the distance between the electric vehicle  10  and the power lines  20  has become the second predetermined distance z 2 , then the angle α of the charging head  26  with respect to the power lines  20  becomes excessively small compared to the angles α 1 , α 2 . Conversely, if the charging head  26  is disposed so that the longitudinal direction of the charging head  26  is perpendicular with respect to the power lines  20  when the rotational angle of the arm portion  86  is at the second angle of rotation θ 2 , and the distance between the electric vehicle  10  and the power lines  20  has become the first predetermined distance z 1 , then the angle α of the charging head  26  with respect to the power lines  20  becomes excessively small compared to the angles α 1 , α 2 . As a result, by the charging head  26  becoming an excessively acute angle with respect to the power lines  20 , a portion (for example, the cover  56 ) other than the power receiving elements  40   p,    40   n  of the charging head  26  interferes with the power lines  20 , and there is a concern that the power receiving elements  40   p,    40   n  cannot come into contact with the power lines  20 . 
         [0066]    Accordingly, by disposing the charging head  26  so that the longitudinal direction of the charging head  26  faces toward the power lines  20  (i.e., so that the charging head  26  and the power lines  20  are disposed face to face) when the rotational angle of the arm portion  86  is at the third angle of rotation θ 3 , even if the distance between the electric vehicle  10  and the power lines  20  varies within a range from the first predetermined distance z 1  to the second predetermined distance z 2 , the power receiving elements  40   p,    40   n  of the charging head  26  can stably be placed in contact with the power lines  20 . 
         [0067]    In the foregoing manner, according to the present embodiment, when the arm portion  86  is deployed so as to be placed at the third angle of rotation θ 3 , the charging head  26  is set so that the longitudinal direction thereof faces toward the power lines  20  perpendicularly with respect to the power lines  20  (i.e., so that the charging head  26  and the power lines  20  are disposed face to face), and the arm portion  86  is deployed up to the first angle of rotation θ 1  which is greater than the third angle of rotation θ 3 . Consequently, it is possible for the power receiving elements  40   p,    40   n  and the power lines  20  to stably be placed in contact with each other, even if the angle α formed by the charging head  26  and the power lines  20  varies due to the variation of the distance between the electric vehicle  10  and the power lines  20 . 
         [0068]    The charging arm  22  includes the actuator  90  that slides along the slide rail  88 , and the spring damper  92 , one end of which is attached rotatably to the arm portion  86 , and another end of which is attached rotatably to the actuator  90 , and the spring damper  92  biases the arm portion  86  in a direction to deploy the arm portion  86  outwardly in the vehicle transverse direction. Accordingly, when the power receiving elements  40   p,    40   n  contact the power lines  20  and the arm portion  86  is returned to the side of the electric vehicle  10 , the power receiving elements  40   p,    40   n  are pressed against the power lines  20  by the biasing force of the spring damper  92 . Consequently, the contact pressure between the power receiving elements  40   p,    40   n  and the power lines  20  can be maintained, and electrical power from the power lines  20  can be supplied in a stable manner to the energy storage device  16 . 
         [0069]    The charging head  26  is attached to the distal end of the arm portion  86  through a bracket  80 , in such a manner that the longitudinal direction of the charging head  26  and a direction in which the arm portion  86  extends define a predetermined angle. Accordingly, when the arm portion  86  is deployed to the third angle of rotation θ 3 , the charging head  26  can easily be attached to the distal end of the arm portion  86 , so that the longitudinal direction of the charging head  26  faces toward the power lines  20  at a direction perpendicular with respect to the power lines  20 . 
         [0070]    Further, the power lines  20  come into contact with the first roller members  42   a  of the power receiving elements  40   p,    40   n,  and the brushes  58   a,    58   b  are placed in contact with the second roller members  42   b  of the power receiving elements  40   p,    40   n.  More specifically, the positions at which the power receiving elements  40   p,    40   n  contact the power lines  20  are shifted in the axial direction of the support shafts  48   a,    48   b  from the positions at which the power receiving elements  40   p,    40   n  contact the brushes  58   a ,  58   b.  Owing thereto, abrasion of the power receiving elements  40   p,    40   n  at the contact position between the power receiving elements  40   p,    40   n  and the power lines  20  can be suppressed. Consequently, the power receiving elements  40   p ,  40   n  and the power lines  20  can stably be kept in contact, and electrical power from the power lines  20  can be supplied in a stable manner to the energy storage device  16 . 
         [0071]    The charging head  26  is equipped with the spring members  70   a,    70   b  that press the brushes  58   a,    58   b  toward the side of the power receiving elements  40   p,    40   n.  Owing to this feature, even in the case that the power receiving elements  40   p,    40   n  or the brushes  58   a,    58   b  are abraded and subjected to wear due to contact between the power receiving elements  40   p,    40   n  and the brushes  58   a,    58   b,  the contact state between the power receiving elements  40   p,    40   n  and the brushes  58   a,    58   b  can be maintained by the spring members  70   a,    70   b.    
         [0072]    In the charging head  26 , the bus bars  60   a,    60   b  that connect the brushes  58   a,    58   b  and the electrical cables  86   a ,  86   b  are retained in a slackened state. Owing thereto, the bus bars  60   a,    60   b  can be allowed to follow along with the movement of the brushes  58   a,    58   b,  and thus, the brushes  58   a,    58   b  can be moved toward the side of the power receiving elements  40   p,    40   n.  Consequently, the contact state between the brushes  58   a,    58   b  and the power receiving elements  40   p,    40   n  can be maintained. 
         [0073]    The power receiving elements  40   p,    40   n  are equipped with the first roller members  42   a  that contact the power lines  20 , and the second roller members  42   b  having the outer circumferential surface of a first radius r 1  and which contact the brushes  58   a,    58   b,  and further, the outer circumferential surface of the first roller members  42   a  include radii that are larger than the first radius r 1 . Owing thereto, the first roller members  42   a  can be placed in contact with respect to the power lines  20 . Further, the circumferential velocity of the outer circumferential surface of the second roller members  42   b  is smaller in comparison with that of the first roller members  42   a , whereby frictional wear and abrasion between the second roller members  42   b  and the brushes  58   a,    58   b  can be suppressed. 
         [0074]    Further, because the charging arm  22  extends outwardly in the vehicle transverse direction from the side portion  10   s  on the driver&#39;s seat  18  side of the electric vehicle  10 , the driver can easily grasp and comprehend the distance between the electric vehicle  10  and the power lines  20 , and by steering a non-illustrated steering handle, the contact state between the power lines  20  and the power receiving elements  40   p,    40   n  of the charging arm  22  can suitably be maintained. 
         [0075]    In the event that a two-wheeled vehicle such as a motorcycle is traveling adjacent to the central line or the central median  39 , ordinarily, a four-wheeled vehicle does not overtake from the side of the central line or the central median  39 . Accordingly, since the charging arm  22  is disposed on the side of the central line or the side of the central median  39  of the electric vehicle  10 , safety of the two-wheeled vehicle can be assured. 
         [0076]    Since the guideline  100  that guides the distance between the electric vehicle  10  and the power lines  20  is provided on the travel path  24 , the distance between the electric vehicle  10  and the power lines  20  can be maintained at an appropriate distance. Consequently, the contact state between the power lines  20  and the power receiving elements  40   p,    40   n  of the charging arm  22  can suitably be maintained. 
         [0077]    Since the power source  34  that supplies electrical power to the power lines  20  is disposed between the travel path  24   a  on which the electric vehicle  10  travels and the travel path  24   b  on which oncoming vehicles travel, the power source  34  can be used in common with the travel path  24   a  and the travel path  24   b.  Consequently, complexity of the electrical wiring from the power source  34  to the power lines  20  of the travel paths  24   a,    24   b  can be suppressed. 
         [0078]    Further, since the recessed part  54   a,  which is recessed at a predetermined depth, is formed on the upper surface of the partition plate  54  of the charging head  26 , even in the case that the power receiving element  40   p  or the power line  20  is subjected to frictional wear due to contact between the power receiving element  40   p  and the power line  20 , wear debris therefrom can be accommodated in the recessed part  54   a.  As a result, the occurrence of adverse effects such as insulation defects or the like in peripheral components by scattering about of such wear debris from the power receiving element  40   p  or the power line  20  can be suppressed. 
         [0079]    When observed from a vertical direction, the recessed part  54   a  is formed in the partition plate  54  so as to surround the contact position between the power receiving element  40   p  and the brush  58   a.  Owing thereto, even if wear debris is generated by frictional wearing between the power receiving element  40   p  and the brush  58   a,  the wear debris can be accommodated in the partition plate  54 . As a result, generation of adverse effects such as insulation defects or the like in peripheral components by wear debris due to contact between the power receiving element  40   p  and the brush  58   a  can be suppressed. 
         [0080]    The charging head  26  is equipped with the two positive electrode and negative electrode power receiving elements  40   p,    40   n  in a pair, which are separated mutually in the vertical direction, and the partition plate  54  is arranged between the pair of power receiving elements  40   p,    40   n  in the vertical direction. Owing thereto, for example, falling down of wear debris, which is generated by the power receiving element  40   p  that is arranged on the upper side, to the side of the power receiving element  40   n  on the lower side, and imparting of an adverse effect on the contact state between the power receiving element  40   n  and the power line  20  can be suppressed. Consequently, electrical power from the power lines  20  can be supplied in a stable manner to the energy storage device  16  through the pair of power receiving elements  40   p,    40   n.    
       Modifications 
       [0081]    The charging head  26  according to the aforementioned embodiment may be modified as described below.  FIG. 12  is a view showing a charging head  26 A according to the present modification, and  FIG. 13  is a view showing a main body portion  44 A illustrated in  FIG. 12 . In the description of the present modification, the capital letter A is appended to the reference numerals concerning constituent elements having the same functions as those of  FIG. 1 , and only necessary locations thereof will be described. As noted above, a through hole  62   a A provided in a base section  52 A of the main body portion  44 A branches into two in the interior of a flange  52   a A, and communicates with two openings  68   a A,  68   a A that are formed in the flange  52   a A. Differently from the above-described embodiment, the through holes  62   a A are formed horizontally in the interior of the base section  52 A, and the cross-sectional areas thereof are of the same size. The recessed part  110  is formed in an upper surface of a partition plate  54 A on the side of the openings  68   a A,  68   a A. The recessed part  110  is formed so that two bus bars  60   a A,  60   a A, which extend from the two openings  68   a A,  68   a A horizontally through the through holes  62   a A, will not interfere with the partition plate  54 A. Using the space that is formed by the recessed part  110 , the two bus bars  60   a A,  60   a A extend from the openings  68   a A,  68   a A in an upwardly bending manner, and are connected to a brush  58   a A through the inside of a first support member  46   a A (not shown). According to the present modification, the two bus bars  60   a A,  60   a A are retained in a slackened state in the interior of a through hole  64   a A of the first support member  46   a A (not shown). Another recessed part  54   a A, which is recessed at a predetermined depth around an outer periphery thereof, is formed on the upper surface of the partition plate (accommodating section)  54 A. Wear debris, which is generated by contact friction between a positive electrode side power line  20   p A and a power receiving element  40   p A, and wear debris, which is generated by contact friction between the power receiving element  40   p A and the brush  58   a A is accommodated by the recessed part  54   a A. 
         [0082]    The communicating state of non-illustrated bus bars  60   b A,  60   b A is the same as that of the bus bars  60   a A,  60   a A. 
         [0083]    More specifically, differently from the above-described embodiment, through holes  62   b A are formed horizontally in the interior of the base section  52 A, and the cross-sectional areas thereof are of the same size. In addition, a recessed part  110  is formed in a lower surface of the partition plate  54 A on the side of openings  68   b A,  68   b A. The recessed part  110  is formed so that the two bus bars  60   b A,  60   b A, which extend from the two openings  68   b A,  68   b A horizontally through the through holes  62   b A, will not interfere with the partition plate  54 A. The two bus bars  60   b A,  60   b A extend from the openings  68   b A,  68   b A in an downwardly bending manner, and are connected to a brush  58   b A through the inside of a second support member  46   b A (not shown). According to the present modification, the two bus bars  60   b A,  60   b A are retained in a slackened state in the interior of a through hole  64   b A of the second support member  46   b A (not shown). 
         [0084]    A recess  112  formed in the upper surface of the partition plate  54 A is formed for the purpose of receiving a support shaft  48   a A therein, and similarly, in the lower surface of the partition plate  54 , a recess (not shown) is formed for the purpose of receiving a support shaft  48   b A therein. 
         [0085]    As shown in  FIG. 14 , an accommodating section  114  in which a recessed part  114   a  is formed on a lower portion of the charging head  26 A (main body portion  44 A) may be provided for accommodating wear debris, which is generated by contact friction between a negative electrode side power line  20   n A and a power receiving element  40   n A, and wear debris, which is generated by contact friction between the power receiving element  40   n A and the brush  58   b A. The recessed part  114   a  is formed on the upper surface of the accommodating section  114 .