Abstract:
A power supply apparatus capable of appropriately supplying electrical power to a power transmission coil even if a foreign object is heated during power supply. The power supply apparatus ( 100 ) is provided with a power supply coil ( 103   a ) opposing a power-receiving unit ( 153 ) provided to a vehicle and supplying power to the power-receiving unit ( 153 ), and a casing ( 103   b ) accommodating the power supply coil ( 103   a ). In the casing ( 103   b ), a first cover ( 202 ) is formed on a surface of the casing ( 103   b ) opposing the power-receiving unit ( 153 ), and a second cover ( 203 ) opposing the first cover ( 202 ) is arranged between the first cover ( 202 ) and the power supply coil ( 103   a ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an electric supply apparatus that contactlessly supplies electric power using electromagnetic induction to an electric reception section provided in a vehicle. 
       BACKGROUND ART 
       [0002]    A typical known contactless electric supply apparatus is one that is placed on a ground surface and supplies electric power to an electric reception section mounted in a vehicle (for example, Patent Literature (hereinafter, abbreviated as PTL) 1). 
         [0003]    In PTL 1, two units, i.e., an electric transmission unit and an electric reception section are provided. The electric transmission unit includes a ring-shaped electric transmission coil and a casing that houses this coil, and is placed on a road surface side position where a vehicle stops, such as a parking space. The electric reception section includes a ring-shaped electric reception coil and a casing that houses this coil, and is placed on the bottom surface of the vehicle at a position that faces the electric transmission unit placed on the ground surface. The surface of the casing that faces the electric reception section of the electric transmission unit (hereinafter referred to as “upper surface”) is formed so as to be in parallel with the radial direction of the electric transmission coil. 
       CITATION LIST 
     Patent Literature 
       [0004]    PTL 1 
         [0005]    Japanese Patent Application Laid-Open No. 2011-10435 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    In the electric supply apparatus according to the related art, however, it is likely that a foreign object is put on the upper surface of the electric transmission unit because the surface of the electric transmission unit is in parallel with the radial direction of the transmission coil. The foreign object on the upper surface involves a problem in that the foreign object is heated to a high temperature by a magnetic flux penetrating the foreign object during electric supply. Moreover, the foreign object heated to a high temperature may cause, for example, a hole at a portion in contact with the foreign object and damage the upper surface. Consequently, the foreign object or the like entering from the damaged portion falls onto the electric transmission coil. This heated foreign object may melt a coating film of a metallic thin wire included in the electric transmission coil and may cause a short circuit between portions of the metallic thin wire of the electric transmission coil. 
         [0007]    It is an object of the present invention to provide an electric supply apparatus that can prevent a foreign object from reaching an electric transmission coil and that can appropriately perform an electric supply process even when the foreign object is heated during electric supply. 
       Solution to Problem 
       [0008]    An electric supply apparatus according to an aspect of the present invention is an apparatus that contactlessly supplies electric power using electromagnetic induction to an electric reception section provided in a vehicle, the apparatus including: a ring-shaped electric supply coil that faces the electric reception section and that supplies electric power to the electric reception section; and a casing that houses the electric supply coil, in which the casing includes: a first cover formed on a surface of the casing, the surfacing facing the electric reception section; and a second cover facing the first cover and being placed between the first cover and the electric supply coil. 
       Advantageous Effects of Invention 
       [0009]    According to the present invention, it is possible to prevent a foreign object from reaching an electric transmission coil and thus to appropriately perform an electric supply process even when the foreign object is heated during electric supply. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a block diagram illustrating an example of the configuration of a charging system according to Embodiment 1 of the present invention; 
           [0011]      FIG. 2  is a perspective view of an electric supply section according to Embodiment 1 of the present invention; 
           [0012]      FIG. 3  is a plane view of  FIG. 2 ; 
           [0013]      FIG. 4  is a sectional view taken along line A-A in  FIG. 2 ; 
           [0014]      FIG. 5  is a sectional view taken along line B-B in  FIG. 2 ; and 
           [0015]      FIG. 6  is a sectional view taken along line C-C in  FIG. 2 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0016]    Hereafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
       Embodiment 1 
       [0017]    &lt;Configuration of Charging System&gt; 
         [0018]      FIG. 1  is a block diagram illustrating an example of the configuration of charging system  10  in Embodiment 1 of the present invention. 
         [0019]    Charging system  10  includes electric supply apparatus  100 , vehicle  150 , storage battery  154 , and charging apparatus  170 . 
         [0020]    Electric supply apparatus  100  is placed on a ground surface or buried so that electric supply section  103  is exposed from land surface g. Electric supply apparatus  100  is provided, for example, in a parking space and supplies electric power to charging apparatus  170  while facing electric reception section  153 , during parking of vehicle  150 . The configuration of electric supply apparatus  100  will be described below. 
         [0021]    Vehicle  150  includes storage battery  154  and charging apparatus  170 , and runs with storage battery  154  as a power source. Vehicle  150  is, for example, an automobile that can run with the electric power of storage battery  154  such as an HEV (Hybrid Electric Vehicle), a PHEV (Plug-in Hybrid Electric Vehicle), or an EV (Electric Vehicle). 
         [0022]    Storage battery  154  stores the electric power supplied from charging apparatus  170 . 
         [0023]    Charging apparatus  170  includes vehicle side control section  151  and electric reception apparatus  160 , and supplies the electric power supplied from electric supply apparatus  100 , to storage battery  154 . The configuration of charging apparatus  170  will be described below in detail. 
         [0024]    Vehicle side control section  151  controls electric reception apparatus  160  to perform various processes associated with charging or various processes associated with the stop of charging. 
         [0025]    Electric reception apparatus  160  supplies the electric power supplied from electric supply apparatus  100 , to storage battery  154  according to the control of vehicle side control section  151 . The configuration of electric reception apparatus  160  will be described below. 
         [0026]    &lt;Configuration of Electric Supply Apparatus&gt; 
         [0027]    Electric supply apparatus  100  includes electric supply side communication section  101 , electric supply side control section  102 , and electric supply section  103 . 
         [0028]    Electric supply side communication section  101  receives an electric supply start signal or an electric supply stop signal from vehicle side communication section  152 . Electric supply side communication section  101  outputs the received electric supply start signal or electric supply stop signal to electric supply side control section  102 . 
         [0029]    Electric supply side control section  102  controls electric supply section  103  to start electric supply according to the electric supply start signal inputted from electric supply side communication section  101 . Electric supply side control section  102  controls electric supply section  103  to stop electric supply according to the electric supply stop signal inputted from electric supply side communication section  101 . 
         [0030]    Electric supply section  103  includes electric supply coil  103   a . Electric supply section  103  supplies the current having a predetermined frequency to electric supply coil  103   a  according to the control of electric supply side control section  102  to thereby supply electric power using electromagnetic induction to electric reception section  153 . This electric supply is performed in an electromagnetic induction system or a magnetic resonance system, for example. The configuration of electric supply section  103  will be described below in detail. 
         [0031]    &lt;Configuration of Electric Reception Apparatus&gt; 
         [0032]    Electric reception apparatus  160  includes vehicle side communication section  152  and electric reception section  153 . 
         [0033]    Vehicle side communication section  152  generates a charging start signal or a charging stop signal according to control of vehicle side control section  151 , and transmits the generated charging start signal or charging stop signal to electric supply side communication section  101 . 
         [0034]    Electric reception section  153  is provided at the bottom portion of vehicle  150 . Electric reception section  153  includes electric reception coil  153   a  and contactlessly faces electric supply section  103  when storage battery  154  is charged. Electric reception section  153  supplies the electric power, which is supplied from electric supply section  103  to electric reception coil  153   a , to storage battery  154  according to the control of vehicle side control section  151 . 
         [0035]    &lt;Configuration of Electric Supply Section&gt; 
         [0036]      FIG. 2  is a perspective view of electric supply section  103 , and  FIG. 3  is a plane view of electric supply section  103  viewed from the direction of electric reception section  153 .  FIG. 4  is a sectional view taken along line A-A in  FIG. 2 ,  FIG. 5  is a sectional view taken along line B-B in  FIG. 2 , and  FIG. 6  is a sectional view taken along line C-C in  FIG. 2 . Hereinafter, the configuration of electric supply section  103  will be described mainly with reference to  FIG. 2  and  FIG. 4 . 
         [0037]    Electric supply section  103  includes electric supply coil  103   a  and casing  103   b.    
         [0038]    Electric supply coil  103   a  is of a hollow ring shape and placed on inner bottom surface (base)  201  of casing  103   b . Electric supply coil  103   a  is connected, for example, to a commercial power source and supplies electric power to electric reception section  153  by supplying a current from this power source. Electric supply coil  103   a  is formed, for example, by winding a metallic thin wire. 
         [0039]    Casing  103   b  includes base  201 , first cover  202 , and second cover  203 . Base  201  is formed, for example, in a square flat plate shape (for example, see  FIG. 3 ). Base  201  is formed of a material, such as aluminum. Electric supply coil  103   a  is placed on base  201 , and first cover  202  and second cover  203  are attached to base  201 . When first cover  202  and second cover  203  are attached to base  201 , casing  103   b  has first cover  202  on a surface that faces electric reception section  153 , and has second cover  203  that faces first cover  202  between first cover  202  and electric supply coil  103   a  in the direction of central axis P 1  of electric supply coil  103   a.    
         [0040]    First cover  202  is formed of, for example, a nonmetallic material, such as a reinforced plastic, having load capacity. For example, first cover  202  may have such load capacity that no damage is caused even when vehicle  150  expected to use electric supply apparatus  100  is mounted on first cover  202 . 
         [0041]    In first cover  202 : flat portion  202   a  and incline portion  202   b  are each formed as a portion of the surface of casing  103   b , which faces electric reception section  153 ; flat portion  202   c  is formed as a portion other than flat portion  202   a  and incline portion  202   b  on the surface of casing  103   b , which faces electric reception section  153 ; side portion  202   d  in connection with incline portion  202   b  and flat portion  202   c  is formed; and side portion  202   e  connected to flat portion  202   c  and base  201  is formed. 
         [0042]    Flat portion  202   a  is formed so as to have one end connected to incline portion  202   b . When casing  103   b  is placed on a ground surface, flat portion  202   a  is formed so as to be located above a hollow portion of electric supply coil  103   a . Flat portion  202   a  is also formed so as to cross central axis P 1  of electric supply coil  103   a.    
         [0043]    Incline portion  202   b  is formed so as to have one end connected to side portion  202   d  and the other end connected to flat portion  202   a . Incline portion  202   b  is formed in a portion where electric supply coil  103   a  is projected when electric supply coil  103   a  is projected on casing  103   b  toward electric reception section  153 , and so as to gradually approach electric supply coil  103   a  toward flat portion  202   a  in the radial direction of electric supply coil  103   a . Note that, the radial direction of electric supply coil  103   a  is a direction orthogonal to central axis P 1  of electric supply coil  103   a.    
         [0044]    Second cover  203  is formed of, for example, a heat-resistant material, such as heat-resistant glass. Second cover  203  is attached, for example, by first reinforcement member  204 . Second cover  203  is also placed between first cover  202  and electric supply coil  103   a  in the direction of central axis P 1  of electric supply coil  103   a  so as to face first cover  202 . For example, second cover  203  is also concentric to electric supply coil  103   a  and is placed so as to cross central axis P 1 . 
         [0045]    The space surrounded by first cover  202 , second cover  203 , and first reinforcement member  204  is sealed. Even when a heated foreign object stops at second cover  203  after melting first cover  202  and falling off, entering of water such as rain through the hole made in first cover  202  may cause a short circuit between portions of metallic thin wire in electric supply coil  103   a . In this regard, sealing the space as described above makes it possible to avoid a situation where water or the like reaches electric supply coil  103   a  when rain water or the like enters from outside. 
         [0046]    First reinforcement member  204  is formed so as to have one end connected to first cover  202  and the other end connected to second cover  203 . First reinforcement member  204  attaches second cover  203  to first cover  202  as described above and also supports first cover  202 . This can secure the withstand load of first cover  202 . First reinforcement member  204  is formed, for example, of an insulator. 
         [0047]    Second reinforcement member  205  is formed so as to have one end connected to second cover  203  and the other end connected to base  201 . Second reinforcement member  205  is also placed in the hollow portion of electric supply coil  103   a . That is, second reinforcement member  205  supports second cover  203 . This can secure the withstand load of second cover  203 . Second reinforcement member  205  is formed, for example, of an insulator. 
         [0048]    &lt;Advantageous Effect of Present Embodiment&gt; 
         [0049]    In the present embodiment, first cover  202  is formed on the surface of the casing  103 , which faces electric reception section  153 . Second cover  203  is placed between first cover  202  and electric supply coil  103   a  in the direction of central axis P 1  of electric supply coil  103   a . That is, casing  103   b  has a dual structure of first cover  202  and second cover  203 . 
         [0050]    Generally, the heat-resistant material used for second cover  203  is a fragile material such as heat-resistant glass. In considering a situation where vehicle  150  is put on first cover  202 , it is not preferable to use such a heat-resistant material for first cover  202 . For this reason, in the present embodiment, the part of first cover  202  which is on the outer side of the casing and on which the tire of vehicle  150  may be put is formed of a member having high load capacity such as reinforced plastic, and the part of second cover  203  which is formed of a heat-resistant material is placed between first cover  202  and electric supply coil  103   a . These covers provide a dual structure. This configuration enables electric supply apparatus  100  providing both load capacity and heat resistance. 
         [0051]    Even when a foreign object on first cover  202  is heated and melts first cover  202 , the foreign object falls onto second cover  203 . Second cover  203  is heat-resistant as described above. Therefore, even if the foreign object heated to a high temperature falls onto second cover  203 , second cover  203  does not melt. Consequently, the foreign object does not contact electric supply coil  103   a . As a result, even when a foreign object is, for example, heated during electric supply and damages first cover  202 , the foreign object does not reach electric supply coil  103   a . Thereby, the heated foreign object can be prevented from falling onto electric supply coil  103   a  and melting a coating film of a metallic thin wire included in electric supply coil  103   a  to cause a short circuit between portions of the metallic thin wire of electric supply coil  103   a . Thus, an electric supply process can be performed appropriately. 
         [0052]    Moreover, in the present embodiment, the heated foreign object does not melt heat-resistant second cover  203 . If a hole is made in the cover by heat of the foreign object and exposes the electric supply coil, a human body or the like can contact the electric supply coil, which results in a security problem. With regard to this problem, in the present embodiment, the heated foreign object stops at second cover  203 , and there is no chance to expose electric supply coil  103   a . This provides an additional advantageous effect in that electric supply apparatus  100  having high security can be provided. 
         [0053]    Moreover, in the present embodiment, in first cover  202 , incline portion  202   b  that gradually approaches electric supply coil  103   a  toward flat portion  202   a  in the radial direction of electric supply coil  103   a  is formed in a portion of casing  103   b  on which electric supply coil  103   a  is projected when electric supply coil  103   a  is projected on casing  103   b  toward electric reception section  153 . Thereby, a foreign object on incline portion  202   b  slides down into flat portion  202   a  that faces the hollow portion of electric supply coil  103   a . Since flat portion  202   a  is distant from the position corresponding to intermediate position  213  between inner edge portion  211  and outer circumference  212  of electric supply coil  103   a , the foreign object on flat portion  202   a  is not easily heated. This can prevent the foreign object from being heated to a high temperature and thereby damaging first cover  202 . 
         [0054]    Furthermore, in the present embodiment, as illustrated in  FIG. 4 , second cover  203  may have a smaller area than the area of first cover  202 . A smaller area of second cover  203  enables first reinforcement member  204  used also for attachment of second cover  203  to be placed at a position closer to the center of casing  103   b  in the radial direction of electric supply coil  103   a . This can appropriately set the location of first reinforcement member  204 . For example, in comparison with the case (not illustrated) where first reinforcement member  204  is connected near side portion  202   d  on incline portion  202   b , first cover  202  can be supported more stably in the case where first reinforcement member  204  is connected near the center of incline portion  202   b  (for example, see  FIG. 4 ). This can secure a higher withstand load of first cover  202 . The location of first reinforcement member  204  may be determined, for example, in consideration of both the viewpoint of the reinforcement for first cover  202  and the viewpoint of protection of a foreign object by second cover  203 . 
         [0055]    Meanwhile, as illustrated in  FIG. 4  in this case, in a region outside the connection point to first reinforcement member  204  in first cover  202 , second cover  203  is not placed in the direction of central axis P 1  of electric supply coil  103   a . However, the region in which second cover  203  is not placed in first cover  202  in the direction of central axis P 1  of electric supply coil  103   a  corresponds to incline portion  202   b , so that it is unlikely that a foreign object stays in the region. Furthermore, the region in which second cover  203  is not placed in the direction of central axis P 1  of electric supply coil  103   a  is distant from electric supply coil  103   a  in comparison with the region in which second cover  203  is placed. Therefore, in the region in which second cover  203  is not placed in first cover  202  in the direction of central axis P 1  of electric supply coil  103   a , even if a foreign object exists, the foreign object is not easily heated. From the above, even if the region in which second cover  203  is not placed in first cover  202  in the direction of central axis P 1  of electric supply coil  103   a  exists, it is unlikely that a foreign object is heated to a high temperature and thereby damages first cover  202 . 
         [0056]    Moreover, in the present embodiment, first cover  202  (in particular incline portion  202   b ) may be covered with a protective cover coated with a material having a frictional coefficient less than a predetermined value. For example, the predetermined value may be set to approximately a value that makes a foreign object on first cover  202  slidable. This enables a foreign object to readily slide on first cover  202  and to surely slide down into flat portion  202   a.    
         [0057]    The disclosure of the specification, drawings, and abstract in Japanese Patent Application No. 2012-073711 filed on Mar. 28, 2012, is incorporated herein by reference in its entirety. 
       INDUSTRIAL APPLICABILITY 
       [0058]    An electric supply apparatus according to the present invention is suitable for contactlessly supplying electric power to an electric reception section provided in a vehicle. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           103  Electric supply section 
           103   a  Electric supply coil 
           103   b  Casing 
           153  Electric reception section 
           201  Base 
           202  First cover 
           202   a ,  202   c  Flat portions 
           202   b  Incline portion 
           202   d ,  202   e  Side portions 
           203  Second cover 
           204  First reinforcement member 
           205  Second reinforcement member 
           211  Inner edge portion 
           212  Outer circumference 
           213  Intermediate position