Abstract:
An induction type charging paddle engages with a receptacle to charge a battery. The charging paddle has a housing and a circuit board, which is located in the housing to control the charging operation. A case is located in the housing to accommodate the circuit board. The case is sealed to prevent the circuit board from becoming wet.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a waterproof structure for charging paddles used in inductive battery chargers. 
     Generally, there is an induction method for charging batteries in electric vehicles. According to this charging method, as shown in FIG. 6, a charging paddle  50  is connected to a cable  63  extending from a power supply unit. The paddle  50  is inserted to a receptacle  51  of a vehicle to charge a battery. 
     The charging paddle  50  is provided with a primary core  52  and a primary coil  53 . The receptacle  51  is provided with a secondary core  54  and a secondary coil  55 . The charging paddle  50  is inserted to a slot  56  of the receptacle  51 . An alternating current supplied from the power supply unit flows through the primary coil  53  to generate an electromotive force in the secondary coil  55  by electromagnetic induction. The battery in the vehicle is charged based on this electromotive force. 
     The charging paddle  50  has an insert head  57  that is inserted in the slot  56  of the receptacle  51  and a grip  58 , which is gripped by an operator. The insert head  57  includes the primary core  52 , the primary coil  53  and a circuit board  59  having a communication device. The communication device carries out wireless communication with a communication device  60  in the receptacle  51 . The communication device in the charging paddle  50  receives information about the vehicle, including the battery capacity, through this communication. 
     The charging paddle  50  has a housing  62  formed by welding two housing components  61 . The cable  63  is introduced into the housing  62  through a lead-in hole defined in the grip  58 . A waterproof grommet  64  is fitted in the lead-in hole. The grommet  64  prevents water from entering the housing  62 . 
     However, for example, if it happens that an operator drops the charging paddle  50  and cracks the housing  62 , water may penetrate the housing  62 . Also, if the cable  63  is pulled very strongly, the waterproof grommet  64  fails to fully seal the lead-in hole, and water may enter the housing  62  through the lead-in hole. Therefore, the circuit board  59  may get wet. 
     SUMMARY OF THE INVENTION 
     It is an objective of the present invention to provide a waterproof structure for an inductive charging paddle, which prevents the circuit board from becoming wet, even if water enters the housing of the charging paddle. 
     In order to attain the above objective, the present invention provides an induction type charging paddle for engaging a receptacle to charge a battery. The charging paddle comprises a housing, a circuit board which is used for controlling the charging of the battery, and a case which is located in the housing to accommodate the circuit board. The case is sealed to prevent the circuit board from becoming wet. 
     Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, which illustrate by way of examples the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention together with the objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
     FIG. 1 is a cross-sectional view showing the charging paddle according to a first embodiment of the present invention; 
     FIG. 2 is a perspective view of the receptacle and the charging paddle shown in FIG. 1; 
     FIG. 3 is a cross-sectional view taken along the line  3 — 3  in FIG. 1; 
     FIG. 4 is an exploded perspective view of the case for the circuit board shown in FIG. 1; 
     FIG. 5 is an enlarged cross-sectional view taken along the line  5 — 5  in FIG. 1; and 
     FIG. 6 is a perspective view showing the receptacle and the charging paddle of the prior art. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of the present invention will be described below referring to FIGS. 1 to  5 . 
     FIG. 2 shows a charging paddle  10  connected to a cable  21  extending from a stationary power supply unit and a receptacle  11  incorporated to a vehicle. 
     The receptacle  11  is provided with a secondary core  12  and a secondary coil  13 , which is wound around a cylindrical magnetic pole  12   a  of the core  12 . The receptacle  11  has a circuit board  14  on which a wireless communication device is mounted. 
     The charging paddle  10  has a housing  15 , as shown in FIG.  2 . The charging paddle  10  includes an insert head  16 , which is inserted to a slot  11 a of the receptacle  11 , and a grip  17 , which is to be gripped by an operator. The housing  15  has a pair of housing members  18   a  and  18   b . The housing members  18   a  and  18   b  are each integrally molded using an infrared-transmitting resin (e.g., a polycarbonate resin), which is colored using an infrared-transmitting pigment. 
     The insert head  16  includes a cylindrical primary core  19  and an annular primary coil  20 , which is fitted around the primary core  19 . 
     As shown in FIG. 1, the grip  17  has a lead-in hole  17   a , in which a waterproof grommet  25  is fitted. The cable  21 , which extends from the power supply unit, is inserted through the waterproof grommet  25  into the housing  15 . 
     As shown in FIGS. 1 and 3, the insert head  16  is provided with a circuit board  22  for communication. The circuit board  22  confirms whether the charging paddle  10  is correctly connected to the receptacle  11 . Further, information about the vehicle, including the battery capacity, is transmitted through the circuit board  22 . 
     In this embodiment, infrared communication is employed as the communication method. The circuit board  22  includes a communication integrated circuit  23  and an infrared communication element  24 . 
     The cable  21  includes electric supply lines  26  connected to the primary coil  20 , power source lines  27  and signal lines  28 , which are connected to the circuit board  22  with the power supply unit. 
     Next, the characteristics of the present invention will be described specifically. 
     The circuit board  22  is contained in a water-proof case  29 . The case  29  is made of a colorless and transparent infrared transmitting resin. The case  29  substantially conforms to the circuit board  22 , as shown in FIG.  1 . 
     As shown in FIG. 4, the case  29  has a first case component  30 , a second case component  31  and an annular gasket  32  located between these two cases  30  and  31 . 
     The first case component  30  has an upright guide wall  30   a . The first case component  30  also has an peripheral groove  30   b  formed along the outer surface of the guide wall  30   a . The gasket  32  is fitted in this groove  30   b . The second case component  31  is fitted about the guide wall  30   a . The first case component  30  contacts the gasket  32 . The circuit board  22  is contained in the first case component  30  and is positioned by the guide wall  30   a.    
     A notch  30   c  is formed in the guide wall  30   a . An opening  33  is defined in the second case component  31  to oppose the notch  30   c . As shown in FIG. 5, the power source lines  27  and signal lines  28  connected to the circuit board  22  are led out through the notch  30   c  and the opening  33  to the outside of the case  29 . 
     As shown in FIG. 4, a notch  30   d  is defined in the first case component  30  to oppose a light-emitting section and a light-receiving section of the communication element  24 . A prism  34  is supported by a pair of pins  30   e  on the external side of the guide wall  30   a  to oppose the notch  30   d . The second case component  31  has a pair of regulating pieces  31   a  for engaging the prism  34 . The prism  34  causes the infrared light radiated from the communication element  24  to exit from both sides of the charging paddle  10 . The prism  34  also leads the infrared radiation coming in from either side of the paddle  10  to the communication element  24 . This enables communication when the charging paddle  10  is inserted to the slot  11   a  (see FIG. 2) in both possible orientations of the paddle  10  with respect to the receptacle  11 . 
     The inner surface of the housing member  18   a  has protrusions, such as ribs (not shown), for locating the first case component  30  in a predetermined position. As shown in FIG. 4, a plurality of fixing pieces  31   b  are formed at the periphery of the second case component  31  to protrude horizontally. Each fixing piece  31   b  contains a hole  36  for receiving a fastener such as a screw  35  (see FIG.  1 ). A plurality of bosses  37  are formed to protrude from the inner surface of the housing member  18   a , at sites corresponding to the fixing pieces  31   b  of the second case component  31 , respectively (only one boss  37  is shown in FIGS.  1  and  5 ). 
     The circuit board  22  is contained in the case  29 , and with the lines  27  and  28  are led out from the notch  30   c  and the opening  33 . The case  29  is located in a predetermined position in the housing member  18   a . The screws  35  secure the fixing pieces  31  to the bosses  37 , respectively, to fix the case  29  to the housing member  18   a . Since the screws  35  are outside of the gasket  32 , the case  29  is hermetically sealed. Further, the notch  30   c  and the opening  33  are hermetically sealed by a sealing resin (e.g., potting material)  38 . 
     As described above, the joint between the first case component  30  and the second case component  31  of the case  29  is sealed by the gasket  32 , and the opening  33  is sealed by the sealing resin  38  to form water-proof seals. 
     This embodiment has the following effects. 
     If water enters the housing  15  through cracks formed in the charging paddle  10  or through the lead-in hole  17   a  of the cable  21 , the circuit board  22  is protected in the hermetically sealed and water-proof case  29 . 
     The communication element  24  on the circuit board  22  performs reliable infrared communication with the receptacle  11  through the housing  15  and case  29 . Further, since the case  29  is colorless and transparent, whether or not the circuit board  22  is set properly in the case  29  can be visually confirmed from the outside of the case  29 . Thus, a defect in the position of the circuit board  22  in the case  29  can be eliminated before the housing members  18   a  and  18   b  are welded. 
     The sealing resin  38  is poured into the opening  33  to seal it, so that the case  29  is fully sealed against moisture. 
     Since the screws  35  are on the external side of the gasket  32 , they do not impair the gasket  32 . For example, if a screw is driven into a location inside the gasket  32 , that location must be additionally sealed. However, such a complicated sealing structure is not necessary. 
     The shape the case  29  substantially conforms to that of the circuit board  22 . This reduces the size of the case  29  to facilitate incorporation of the case  29  into the housing  15 . Further, the circuit board  22  is correctly positioned by the guide wall  30   a.    
     Since the prism  34  is attached to the case  29 , the prism  34  can be easily positioned with respect to the communication element  24  by merely setting the circuit board  22  in the case  29 . 
     The above embodiment can be modified as follows. 
     The gasket  32  may be replaced with a sealing resin, or a liquid sealing material may be applied to the joint faces. 
     The case  29  may be fixed to the housing  15  using, for example, an adhesive. 
     The opening  33  may be sealed with a sealing material such as a rubber. 
     While the case  29  includes the first case component  30  and the second case component  31 , the lid-like case component may be bonded to the housing  15  with a sealing material. 
     The case may contain a plurality of circuit boards. 
     The method of communication is not limited to infrared communication. For example, an antenna may be contained in the housing  15  to enable radio communication. In this case, the material of the case  29  is not limited to infrared transmitting resin, and the case  29  may be opaque. Further, a combination of infrared communication and radio wave communication may be used as the communication method. 
     Circuit boards for charging control devices other than the communication device may be contained in the case  29 . Also, more than one case  29  may be incorporated, as necessary. 
     The present invention may be applied not only to a vehicle charging paddle but also to various kinds of battery-powered apparatuses, such as self-propelled robots. 
     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. 
     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 of the appended claims.