Abstract:
An electromagnetic induction type connection terminal for connecting a power supply station with a battery for charging the battery has a charging paddle and a charging receptacle. The charging paddle has a primary coil that is supplied with a current from the power supply station. The charging receptacle has a secondary coil connected to the battery. When the primary coil is supplied with a current from the power supply station with the charging paddle plugged into the charging receptacle, an electromotive force is induced into the secondary coil. The charging receptacle has an enclosure for accommodating the secondary coil. The enclosure forms a shield against electromagnetic waves. The charging receptacle has a communication unit for communicating information with the charging paddle to control the charging. The communication unit is located within the enclosure.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a charging receptacle for use in an induction type charging apparatus for charging a battery of an electric vehicle or the like. 
     Conventionally, a conduction type charging apparatus and an induction type charging apparatus have been utilized for charging batteries of electric vehicles. The conduction type charging apparatus has a contact type connection terminal for directly connecting a power supply positioned external to a vehicle with a battery equipped in the vehicle. In contrast, the induction type charging apparatus has a non-contact type connection terminal for connecting a power supply with a battery through electromagnetic induction. The induction type charging apparatus is less susceptible to a contact failure. In addition, the induction type charging apparatus is smaller than the conduction type charging apparatus, so the induction type charging apparatus has drawn particular attention in recent years. 
     FIG. 5 illustrates a connection terminal of a conventional induction type charging apparatus. The connection terminal has a charging paddle  61 , and a charging receptacle  71  for receiving the charging paddle  61 . The charging paddle  61  is connected to a cable  62  extending from an external power supply station (not shown). The charging receptacle  71  is equipped in an electric vehicle, and connected to a battery also equipped in the vehicle. 
     The charging receptacle  71  has an enclosure  75 , an inserting hole  72  formed through the enclosure  75 , a power receiving core  73  accommodated in the enclosure  75 , and a power receiving coil  74  contained in the enclosure  75  and wound around the power receiving core  73 . For reducing the time required for charging, i.e., for achieving rapid charging, some charging apparatuses for electric vehicles use high frequencies and high power. For example, a charging apparatus that uses 430 volts and high frequencies (100 kHz to 370 kHz) to produce power of 80 kilowatts has been developed. In regard to this type of charging apparatus, the charging receptacle  71  is accommodated in the enclosure  75 , which is shielded against the noise to prevent external noise of radio waves, electromagnetic waves and so on from entering the connection terminal, and to prevent emission of noise due to a large current at a high frequency handled by the connection terminal itself. 
     The charging paddle  61  has an distal end  63 , which contains a power transmitting core  64  and a power transmitting coil  65  wound around the power transmitting core  64 . For supplying power, the charging paddle  61  is inserted into an inserting hole  72  of the charging receptacle  71  to place the power transmitting coil  65  upon the power receiving coil  74 . Then, the power supply station passes a current (alternate current) through the power transmitting coil  65  to induce power in the power receiving coil  74 . 
     A plurality of ventilation holes  76  are formed around the inserting hole  72  of the enclosure  75  of the charging receptacle  71  for introducing external air. When heat is generated during charging from the power transmitting coil  65  of the charging paddle  61  and the power receiving coil  74  of the charging receptacle  71 , external air is introduced through the holes  76 , and is exhausted to the outside by a cooling fan  77  on the opposite side of the enclosure  75 . In this way, the heat is discharged to the outside. 
     The charging apparatus also includes an interlock function for starting conduction after confirming that the charging paddle  61  is securely inserted into the charging receptacle  71 ; a function of determining a charging rate (power value) from a power supply station external to the vehicle based on a vehicle determination such as the voltage of an on-vehicle battery or the like; and a function of charging while monitoring condition such as the liquid temperature of the on-vehicle battery. Suitable charging conditions are set through communications of information between the vehicle and the external power supply station. Consequently, the power supply station external to the vehicle supplies appropriate power for the preferred charging conditions to the power transmitting coil  65  of the charging paddle  61  through the cable  62 . 
     The transmission and reception of the information are performed by a communication unit  78  attached on the enclosure  75  of the charging receptacle  71  and a communication unit  66  contained in the charging paddle  61  through wireless communications. The communication unit  78  is accommodated in a noise shielded case  79  for preventing malfunctions due to radio waves of portable telephones or other devices. 
     However, due to the structure in which the communication unit  78  is accommodated in the case  79  attached on the enclosure  75  of the charging receptacle  71 , the resultant charging receptacle  71  is large. This is a problem for electric vehicles, which are required to be smaller. 
     In addition, a space must be provided for insulation between the noise shielded case  79  of the communication unit  78  and a current-carrying part of a communication circuit. This also increases the size of the communication unit  78 . 
     During charging, the power receiving coil  74  and the power transmitting coil  65  generate heat. Then, the heat is conducted from the enclosure  75  of the charging receptacle  71  to the communication unit  78  carried on the enclosure  75  of the charging receptacle  71  to elevate the temperature of the communication unit  78 . As a result, the communication unit  78  become unstable due to the elevated temperature, particularly when the atmospheric temperature is high as in summer. 
     Also, for securely inserting the charging paddle  61  into the charging receptacle  71  when the battery is charged, guiding members (not shown) must be formed on the top and bottom within the inserting hole  72  of the enclosure  75  of the charging receptacle  71 . The formation of the guiding members also increases manufacturing costs. 
     Moreover, the enclosure  75  of the charging receptacle  71  is loaded with the weight of such parts as the power receiving core  73  of the charging receptacle  71  accommodated therein, the power receiving coil  74 , the cooling fan  77 , and other parts. Also, when the charging paddle  61  is inserted into the enclosure  75 , and the enclosure  75  is required to have strength enough to withstand this weight. In addition, an operator may inadvertently twist the charging paddle  61  when inserting or removing the charging paddle  61 , so the enclosure  75  is also required to withstand such torsion. It is therefore necessary to form the enclosure  75  of a strong material, thereby increasing manufacturing costs. 
     The communication units  66 ,  78  used in the charging paddle  61  and the charging receptacle  71  wirelessly communicate with each other. The frequency band of radio waves available to the wireless communication differs from one country or area (zone) to another. Therefore, for commercializing the charging paddle  61  and the charging receptacle  71 , a plurality of different types must be manufactured to adapt to the available frequency bands in respective countries and areas. Thus, the provision of a large number of types increase the manufacturing costs of the charging receptacle  71 . 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a charging receptacle which is capable of maintaining a good shielding capability against electromagnetic noise while reducing the size. 
     It is another object of the present invention to provide a charging receptacle which is manufactured at a low cost. 
     To achieve the above objectives, the present invention provides a charging receptacle for an electromagnetic induction type connection terminal for connecting a power supply station with a battery for charging the battery. The connection terminal has a charging paddle that plugs into the charging receptacle. The charging paddle has a primary coil supplied with a current from the power supply station. The charging receptacle includes a secondary coil connected to the battery, an enclosure for accommodating the secondary coil, and a communication unit for communicating information with the charging paddle to control the charging. The secondary coil produces an inductive electromotive force when the primary coil is supplied with current from the power supply station and when the charging paddle is plugged into the charging receptacle. The enclosure forms a shield against electromagnetic waves. The communication unit is within the enclosure. 
     Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawing in which: 
     FIG. 1 is a cross-sectional view illustrating how a charging paddle is inserted in a charging receptacle, for explaining one embodiment of the present invention; 
     FIG. 2 is a perspective view illustrating a connection terminal which comprises a charging paddle and a charging receptacle according to the present invention; 
     FIG. 3 is a perspective view illustrating a communication case for a communication unit; 
     FIG. 4 is a perspective view illustrating the configuration of an induction type charging apparatus according to the present invention; and 
     FIG. 5 is a perspective view illustrating a connection terminal of a conventional induction type charging apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An induction type charging apparatus according to one embodiment of the present invention will hereinafter be described with reference to FIGS. 1 to  4 . As illustrated in FIG. 4, the induction type charging apparatus  1  has a connection terminal that includes a charging paddle  2  and a charging receptacle  3  for receiving the charging paddle  2 . A cable  5  extends from a power supply station  4 . The charging paddle  2  is attached to the distal end of the cable  5 . The charging receptacle  3  is located at a predetermined position within an electric vehicle  6  (for example, in front of a hood as shown in FIG.  4 ), and connected to a battery  11  also located in the electric vehicle  6 . 
     The charging paddle  2  has an distal end  7  and a grip  8 . The distal end  7  can be inserted into and removed from a socket  9  of the charging receptacle  3 . The distal end  7  has a front surface and a back surface that have the same shape. Therefore, the distal end  7  can be plugged into the charging receptacle  3  when the distal end  7  is facing either front or back. 
     For charging the electric vehicle  6 , the distal end  7  of the charging paddle  2  is plugged into the socket  9  of the charging receptacle  3 , as indicated by broken lines in FIG.  4 . An alternating current of a predetermined value is sent from the power supply station  4  to the charging paddle  2  through the cable  5 . The alternating current is received by the charging receptacle  3  through electromagnetic induction to charge the battery  11  equipped in the electric vehicle  6 . 
     This non-contact charging apparatus  1  comprises an interlock function for starting conduction after confirming that the charging paddle  2  is securely inserted into the charging receptacle  3 ; a function of determining a charging rate (power value) from the power supply station  4  external to the vehicle based on a vehicle determination such as the voltage of the battery  11  or the like; and a function of charging while monitoring conditions such as the liquid temperature of the battery  11 . A controller  10  located in the power supply station  4  sets suitable charging conditions through communication of information between the vehicle and the external power supply station  4 . Consequently, the power supply station  4  supplies appropriate power for preferred charging conditions to the charging paddle  2  through the cable  5 . 
     The structure of the charging paddle  2  will be described. FIG. 1 is a cross-sectional view illustrating how the charging paddle  2  is inserted in the charging receptacle  3 . FIG. 2 is a perspective view illustrating the connection terminal, which includes the charging paddle  2  and the charging receptacle  3 . In FIG. 2, the charging paddle  2  has the distal end  7 , which includes a substantially cylindrical primary core  21  made of ferrite and a primary coil  22  wound around the primary core  21 . The primary coil functions as a power transmitting coil. The charging paddle  2  also has a grip  8  and contains a communication unit  23  within the distal end  7  between the vicinity of the grip  8  and the primary coil  22 . 
     As illustrated in FIG. 1, the communication unit  23  has a communication circuit  25  including a plurality of circuit elements mounted on a substrate  24 . An infrared sensor  26  is located on each of a front surface and a back surface (the top and the bottom in FIG. 1) of the substrate  24 . The charging paddle  2  communicates information with the charging receptacle  3  through the infrared sensors  26 . The infrared sensors  26  are located on the front surface and the back surface of the substrate  24  so that information can be communicated whether the charging paddle  2  is facing frontward or backward when it is plugged into the charging receptacle  3 . A jacket of the charging paddle  2  is formed of infrared-transparent resin, which readily transmits infrared rays for permitting the communication of information with the charging receptacle  3  through the infrared sensors  26 . 
     The structure of the charging receptacle  3  will be described. As illustrated in FIG. 2, the charging receptacle  3  has an enclosure  30 , which is attached to the electric vehicle  6 . The enclosure  30  has a main case  31 , and a fan container  32  and a lid  33  coupled to the main case  31 . In this embodiment, the main case  31  is formed of aluminum. Two side surfaces of the main case  31  (the right side and the upper side in FIG. 1) are open. In the right side opening of the main case  31 , the fan container  32 , which is made of iron, is fixed to the main case  31 . In the upper side opening of the main case  31 , a plate-like lid  32 , which is made of iron, is secured to the main case  31  with screws  34 . A motor  35  and a fan  36  rotated by the motor  35  are located in the fan container  32 . 
     Also, in FIG. 1, an outwardly extending hollow guide  50  is formed on the left side of the main case  31 . A port  37  is formed at the outer end of the guide  50  for receiving the charging paddle  2 . The guide  50  has a rectangular cylindrical shape. The distal end  7  of the charging paddle  2  is inserted into the guide  50  through the port  37 , and is guided into a space within the enclosure  30 . In other words, the charging paddle  2  is plugged into the charging receptacle  3  through the port  37 . 
     A plurality of guiding springs  37   a  are located on upper and lower inner surfaces of the guide  50 . The guiding springs  37   a , which are formed of curved copper plates, extend in the width direction of the enclosure  30 . As illustrated in FIG. 1, when the charging paddle  2  is fully plugged into the charging receptacle  3 , the guiding springs  37   a  urge the jacket of the charging paddle  2  from both sides. In this embodiment, conductive particles are impregnated in an outer peripheral portion, including the jacket, of the charging paddle  2  that contains the guiding springs  37   a . Thus, the outer peripheral portion is electrically conductive. 
     A first core  38  and a second core  39 , both made of ferrite, are located in the enclosure  30 . The first core  38  has a central protrusion  38   a , which is designed such that the distal end  7  of the charging paddle  2  can pass through a space between the protrusion  38   a  and the second core  39  when the charging paddle  2  is plugged in. As illustrated in FIG. 1, when the charging paddle  2  is fully plugged in, the central protrusion  38   a  opposes the primary core  21  of the charging paddle  2 . 
     A coil substrate  40  is located around the central protrusion  38   a . A plurality of secondary coils  40   a  are laminated on the coil substrate  40 . The secondary coils  40   a  function as a power receiving coil. As illustrated in FIG. 1, the coil substrate  40  is supported by a base  41 , which is formed by partially depressing the main case  31 . Then, a plurality of guiding plates  42  are arranged on the top surface of a region of the coil substrate  40  near the port  37  along the direction in which the charging paddle  2  is inserted. 
     Opposite to the guiding plates  42 , a communication case  44  for the communication unit  43  is secured on the inner side of the lid  33  by screws  45 . Stated another way, the communication case  44  (communication unit  43 ) is placed at a position near the port  37  within the enclosure  30 . As illustrated in FIG. 3, a plurality of guiding pieces  44   b  are arranged on a bottom surface  44   a  of the communication case  44  at predetermined intervals. The guiding pieces  44   b  function as guiding members formed to extend along the direction in which the charging paddle  2  is inserted. The guiding pieces  44   b  and the guiding plates  42 , which are arranged on the coil substrate  40 , smoothly guide the charging paddle  2 . 
     A substrate  46  is located in the communication case  44 . A communication circuit  47  including a plurality of circuit elements is mounted on the substrate  46 . The substrate  46  is also provided with an infrared sensor  48 . The infrared sensor  48  is placed such that the infrared sensor  48  opposes the infrared sensor  26  located on the communication unit  23  of the charging paddle  2  when the charging paddle  2  is fully inserted, as illustrated in FIG.  1 . The communication case  44  is formed of a synthetic resin that has electrically insulating and infrared-transmission properties. Therefore, the communication unit  23  of the charging paddle  2  and the communication unit  43  of the charging receptacle  3  can communicate information through the infrared sensors  26 ,  48 , respectively. 
     A plurality of ventilation holes  49  for permitting entry of external air are formed on each surface of the main case  31  near the inserting port  37 . A passage  32   a  is formed through a surface of the fan container  32  close to the main case  31 . An exhaust hole  32   b  is formed through a surface of the fan container  32  away from the main case  31 . As the fan  36  is rotated by the motor  35 , external air enters the enclosure  30  through the ventilation holes  49 . The air is guided toward the fan container  32  through a gap between the guiding pieces  44   b  of the communication case  44  and a gap between the guiding plates  42 . The external air enters the fan container  32  through the passage  32   a , and is then exhausted to the outside through the exhaust port  32   b.    
     In the present invention, the communication case  44  of the communication unit  43  is secured with screws  45  on the inner side of the lid  33 . In other words, the communication case  44  (communication unit  43 ) is positioned within the enclosure  30 . Thus, the communication unit  43  does not protrude, so that the charging receptacle  3  is reduced in size. 
     In addition, since the main case  31  is made of aluminum, while the fan container  32  and the lid  33  are made of iron, the charging receptacle  3  is strong. 
     The communication unit  43  is surrounded by metals, such as the aluminum main case  31  and the iron lid  33 , which exhibit high shielding capabilities against electromagnetic noise. For this reason, the communication case  44  for the communication unit  43  need not function as a shield against electromagnetic noise, so that the communication case  44  can be formed of a synthetic resin. The use of synthetic resin reduces the weight of the communication case  44 . 
     The communication unit  43  is positioned near the port  37 . External air introduced through the ventilation hole  49  immediately passes by the communication case  44  of the communication unit  43 , so that the communication unit  43  is efficiently cooled. 
     The communication case  44  for the communication unit  43  is formed of a synthetic resin having an electrically insulating property. This eliminates the need for a special insulating member exclusively for insulating between the communication unit  43  and the charging receptacle  3 . Consequently, the number of parts and the number of assembling steps are reduced. 
     The guiding plates  42  are arranged on the coil substrate  40 , and the guiding pieces  44   b  are arranged on the bottom surface  44   a  of the communication case  44 . Therefore, the charging puddle  2  is smoothly guided along the guiding plates  42  and the guiding pieces  44   b.    
     The guiding pieces  44   b  are formed integrally on the bottom surface  44   a  of the communication case  44 , while the guiding plates  42  are integrally formed on the coil substrate  40 . This eliminates the need for a special guiding member exclusively for guiding the charging paddle  2 . Consequently, the number of parts and the number of assembling steps are reduced. 
     The communication units  23 ,  43  communicate with each other by infrared rays. The infrared-based communication can be defined in accordance with a common standard irrespective of countries and regions, unlike the radio wave communications which differ in available frequency band from one country or region to another. Since the communication units conform to a unified standard, the manufacturing cost is reduced. 
     A plurality of the guiding springs  37   a  made of copper plates are arranged in the port  37  in the width direction of the enclosure  30 , and the outer peripheral portion including the jacket of the charging paddle  2  is electrically conductive. Thus, when the charging paddle  2  is fully inserted, a reliable shield against electromagnetic noise is located between the port  37  and the charging coupler  2 . 
     It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the invention may be embodied in the following forms. 
     The main case  31  may be formed of a metal other than aluminum such as iron or a synthetic resin that can shield electromagnetic noise and maintain rigidity. 
     The fan container  32  may be integrally formed with the main case  31  using the same material. 
     The lid  33  may be formed of a metal other than iron such as a aluminum or a synthetic resin that can shield electromagnetic noise and maintain rigidity. 
     The communication case  44  may be directly secured on the inner side of the main case  31  with fasteners such as screws. 
     The fan container  32  may be fixed on a surface of the main case  31  other than the side surface opposing the port  37  of the main case  31 . 
     Between the communication case  44  and the communication unit  23  of the charging paddle  2 , only those parts required for communications may be formed of an infrared-transmission synthetic resin, and those parts not involved in communications may be formed using an insulating silicone resin, epoxy resin, or ceramic. 
     While the communication case  44  is positioned near the port  37  of the main case  31 , the communication case  44  may be located at another position such as near the fan container  32 , as long as the position permits the communication unit  43  in the communication case  44  to communicate with the communication unit  23  of the charging paddle  2 . 
     Other than inserting the charging paddle  2  into the charging receptacle  3 , the charging paddle  2  may be coupled to the charging receptacle  3  in any way as long as the secondary coil  40   a  of the coil substrate  40  is positioned close to the primary coil  22  of the charging paddle  2 . 
     The charging receptacle  3  may be applied to a charging receptacle of any charging apparatus for machines other than vehicles. 
     Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.