Abstract:
Disclosed herein is a voltage detecting device including: a voltage detecting circuit that is provided for each of a plurality of battery cell groups configuring a battery and detects a voltage of the battery cell group; a control circuit that is insulated from the voltage detecting circuit and controls the battery on the basis of the voltage; a control circuit board equipped with the control circuit; a first communicating element mounted on the control circuit board; a voltage detecting circuit board that is equipped with the voltage detecting circuit and is disposed in parallel to the control circuit board; and a second communicating element that is mounted on the voltage detecting circuit board and is capable of contactless communication with the first communicating element; the first communicating element and the second communicating element being disposed opposed to each other.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present claims priority under 35 U.S.C. §119 to Japanese Patent Application No 2014-101331 filed in the Japan Patent Office on May 15, 2014, the entire content of which is hereby incorporated by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a voltage detecting device. 
       BACKGROUND OF THE INVENTION 
       [0003]    Japanese Patent Laid-open No. Hei 9-23009 discloses a communicating device that is suitable for information communications of a measuring device attached to a battery mounted in an automobile or the like and does not need connecting by a connector. This communicating device has a measuring device that measures information on the voltage, temperature, pressure, and so forth of the battery and a control device that controls the battery on the basis of the information measured by the measuring device. 
         [0004]    The measuring device and the control device are connected to each other via a pair of communicating elements, and the pair of communicating elements are capable of transmitting a signal by using wireless communications through placement of the battery on a battery housing base. 
       SUMMARY OF THE INVENTION  
       [0005]    In the above-described patent document, although a structure in which connecting by a connector is eliminated by using wireless communications, the control device and the measuring device are connected with the intermediary of the battery housing base. This causes a problem that increase in the number of measuring devices leads to increase in the size of the device. 
         [0006]    The present disclosure is made in view of such circumstances and it is desirable to achieve size reduction of a voltage detecting device that detects the voltage of a battery. 
         [0007]    According to an embodiment of the present disclosure, there is provided a voltage detecting device including a voltage detecting circuit that is provided for each of a plurality of battery cell groups configuring a battery and detects the voltage of the battery cell group and a control circuit that is insulated from the voltage detecting circuit and controls the battery on the basis of the voltage. The voltage detecting device further includes a control circuit board equipped with the control circuit, a first communicating element mounted on the control circuit board, a voltage detecting circuit board that is equipped with the voltage detecting circuit and is disposed in parallel to the control circuit board, and a second communicating element that is mounted on the voltage detecting circuit board and is capable of contactless communication with the first communicating element. The first communicating element and the second communicating element are disposed opposed to each other. 
         [0008]    The voltage detecting device may further include a discharge element that is mounted on the voltage detecting circuit board and discharges the battery cell group in an overcharged state and an insulating resin plate disposed between the control circuit board and the voltage detecting circuit board. 
         [0009]    Alternatively, the voltage detecting device may further include a discharge element that is mounted on the voltage detecting circuit board and discharges the battery cell group in an overcharged state and a metal cover that is in contact with the discharge element and covers at least part of the voltage detecting circuit board. 
         [0010]    According to the embodiment of the present disclosure, the control circuit board and the voltage detecting circuit board are disposed in parallel, with the first communicating element and the second communicating element set opposed to each other. This can reduce the size of the voltage detecting device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The advantages of this invention will become apparent in the following description taken in conjunction with the drawings, wherein: 
           [0012]      FIG. 1  is a perspective view of a battery and a voltage detecting device according to a first embodiment of the present disclosure; 
           [0013]      FIG. 2A  is a sectional view of the voltage detecting device according to the first embodiment of the present disclosure and  FIG. 2B  is an enlarged view of a part A shown in  FIG. 2A ; 
           [0014]      FIG. 3  is a circuit diagram of the voltage detecting device according to the first embodiment of the present disclosure; and 
           [0015]      FIG. 4  is a sectional view of a voltage detecting device according to a second embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Embodiments of the present disclosure will be described below with reference to the drawings. 
       First Embodiment 
       [0017]    A voltage detecting device according to a first embodiment of the present disclosure is mounted in a moving vehicle having a battery, such as an electric vehicle (EV) or a hybrid vehicle (HV). The battery is e.g. a secondary battery (rechargeable battery) such as a lithium ion secondary battery and is disposed at the bottom part of the moving vehicle as a battery pack having a rectangular parallelepiped shape. 
         [0018]    As shown in  FIG. 1 , a voltage detecting device  1  is fixed to a side surface of a battery B. The battery B includes plural (five, in the present embodiment) battery modules J 1  to J 5  and each of the battery modules J 1  to J 5  has plural battery cells (battery cell group  12 , see  FIG. 3 ). The voltage detecting device  1  monitors the voltage state of the battery cell groups  12 . 
         [0019]    The voltage detecting device  1  includes: a resin case  3  fixed to the side surface of the battery B; a metal cover  4  that is used in combination with the resin case  3  and forms a board housing space  5  between the metal cover  4  and the resin case  3 ; and a battery electronic control unit (ECU) board  6  and plural cell voltage sensor boards  7  that are housed in the board housing space  5 . 
         [0020]    The battery ECU board  6  is equipped with a processor  80  (see  FIG. 3 , control circuit) configured to control the battery B. The cell voltage sensor board  7  is equipped with an integrated circuit  30  (voltage detecting circuit, see  FIG. 3 ) having functions to measure at least the cell voltage of the battery cell group  12  and transmit information on the cell voltage to the battery ECU board  6 . 
         [0021]    The voltage detecting device  1  is obtained by housing the battery ECU board  6  and the plural cell voltage sensor boards  7  inside the casing formed of the resin case  3  and the metal cover  4  and integrating these components into a package as one unit. The integrated circuit  30  is electrically insulated from the processor  80  and is communicably connected to the processor  80 . 
         [0022]    The resin case  3  is a tray-shaped case on which the battery ECU board  6  and the cell voltage sensor boards  7  can be placed and is fixed to the side surface of the battery B by using fastening measures such as bolts. As shown in  FIG. 2A , the resin case  3  has a base part  9  and a wall part  10  protruding from the edge part of the base part  9 . 
         [0023]    The base part  9  of the resin case  3  has a rectangular plate shape having an outer shape slightly larger than the battery ECU board  6 . Furthermore, on the base part  9  of the resin case  3 , plural locating pins  11  protruding in the same direction as the protrusion direction of the wall part  10  and toward the opposite side to the battery B are formed. 
         [0024]    The locating pins  11  settle the positions of the battery ECU board  6  and the cell voltage sensor boards  7  in such a manner that the battery ECU board  6  is disposed in parallel to the cell voltage sensor boards  7  when the battery ECU board  6  and the cell voltage sensor boards  7  are housed in the resin case  3 . By being located by the locating pins  11 , the battery ECU board  6  and the cell voltage sensor boards  7  are so disposed that, as shown in  FIG. 1 , the plural cell voltage sensor boards  7  disposed in parallel at a predetermined interval from the battery ECU board  6  are lined up in the longitudinal direction of the battery ECU board  6 . 
         [0025]    At least two locating pins  11  are formed per one cell voltage sensor board  7  and all locating pins  11  penetrate the battery ECU board  6 . 
         [0026]    Each locating pin  11  has a circular pillar shape and is so formed that the diameter decreases in a stepwise manner from the base end part to the tip part. Specifically, the locating pins  11  each have a locating pin first portion  13  closest to the tip side, a locating pin third portion  15  closest to the base end side, and a locating pin second portion  14  between the locating pin first portion  13  and the locating pin third portion  15 . The diameter of the locating pin second portions  14  is set larger than that of the locating pin first portions  13 . The diameter of the locating pin third portions  15  is set larger than that of the locating pin second portions  14 . 
         [0027]    In the battery ECU board  6 , plural locating holes  17  corresponding to the locating pins  11  are formed. That is, when the battery ECU board  6  is attached to the resin case  3 , the position of the battery ECU board  6  is settled by insertion of the locating pins  11  into the locating holes  17  of the battery ECU board  6 . The locating holes  17  of the battery ECU board  6  have a diameter that is slightly larger than that of the locating pin second portions  14  of the locating pins  11  and is smaller than that of the locating pin third portions  15 . 
         [0028]    The locating pin third portions  15  are so formed that the battery ECU board  6  is supported at such a height as to be disposed in parallel to the base part  9  of the resin case  3 . 
         [0029]    In the wall part  10  of the resin case  3 , a first support part  18  having a first support surface  19  to support the battery ECU board  6  is formed. The first support part  18  is so formed that the height of the first support surface  19  from the base part  9  is substantially the same as that of the upper ends of the locating pin third portions  15  from the base part  9 . 
         [0030]    The battery ECU board  6  is provided with a connector  20  and the connector  20  is so attached as to be exposed to the outside of the board housing space  5  when the metal cover  4  is attached to the resin case  3 . 
         [0031]    The cell voltage sensor board  7  is formed with a smaller size than the battery ECU board  6 . For example, the cell voltage sensor board  7  is about one-fifth of the size of the battery ECU board  6  and the plural cell voltage sensor boards  7  can be housed in the board housing space  5  in such a manner as to be lined up in the longitudinal direction of the battery ECU board  6 . 
         [0032]    In the cell voltage sensor boards  7 , plural locating holes  22  corresponding to the locating pins  11  are formed. The locating holes  22  of the cell voltage sensor boards  7  have a diameter that is slightly larger than that of the locating pin first portions  13  and is smaller than that of the locating pin second portions  14 . 
         [0033]    The locating pin third portions  15  are so formed that the battery ECU board  6  is supported at such a height as to be disposed in parallel to the base part  9  of the resin case  3 . 
         [0034]    The locating pin second portions  14  are so formed that the cell voltage sensor board  7  is supported at such a height as to be disposed in parallel to the base part  9  of the resin case  3  and the battery ECU board  6 . In other words, due to the supporting of the battery ECU board  6  by the locating pin third portions  15  and the supporting of the cell voltage sensor board  7  by the locating pin second portions  14 , the battery ECU board  6  and the cell voltage sensor board  7  are disposed at a predetermined interval, with their major surfaces parallel to each other. 
         [0035]    The cell voltage sensor board  7  is provided with a connector  23  and the connector  23  is so attached as to be exposed to the outside of the board housing space  5  when the metal cover  4  is attached to the resin case  3 . 
         [0036]    The metal cover  4  has such a shape as to cover the battery ECU board  6  and the cell voltage sensor boards  7  except for the connectors  20  and  23  in cooperation with the resin case  3 . The metal cover  4  has a cover surface  8  that is a major surface parallel to the base part  9  of the resin case  3 . 
         [0037]    Communicating elements  25  and  26  capable of wireless communications with each other are mounted on the battery ECU board  6  and the cell voltage sensor board  7 . 
         [0038]    The first communicating element  25  is mounted on the battery ECU board  6  and on its surface opposed to the cell voltage sensor board  7 . The second communicating element  26  configured to transmit the cell voltage is mounted on the cell voltage sensor board  7  and on its surface opposed to the battery ECU board  6 . 
         [0039]    The first communicating element  25  and the second communicating element  26  are disposed opposed to each other across a distance allowing wireless communications with each other. Specifically, the first communicating element  25  and the second communicating element  26  are disposed at substantially the same position when being viewed from the direction orthogonal to the major surfaces of the battery ECU board  6  and the cell voltage sensor board  7  disposed in parallel to each other. 
         [0040]    As shown in  FIG. 2B , the first communicating element  25  has a core  27   a  of a magnetic material, a coil  28   a  wound around the core  27   a,  and an insulating resin  29   a  covering the core  27   a  and the coil  28   a.  The second communicating element  26  has a core  27   b  of a magnetic material, a coil  28   b  wound around the core  27   b,  and an insulating resin  29   b  covering the core  27   b  and the coil  28   b.  Both ends of the coil  28   b  of the second communicating element  26  mounted on the cell voltage sensor board  7  are connected to the integrated circuit  30 . The coil  28   a  of the first communicating element  25  mounted on the battery ECU board  6  is connected to the processor  80 . 
         [0041]    The coil  28   a  is a primary coil. Furthermore, the coil  28   b  is a secondary coil. The coil  28   a  and the coil  28   b  are so disposed as to have polarities opposite to each other and form a pulse transformer. 
         [0042]    As shown in  FIG. 2A , a discharge resistor  31  is mounted on the cell voltage sensor board  7  and on its surface on the opposite side to the surface facing the battery ECU board  6 . One end of the discharge resistor  31  is connected to the positive electrode of the battery cell group  12  and the other end of the discharge resistor  31  is connected to the ground via a switching element provided inside the integrated circuit  30 . 
         [0043]    When the battery cell group  12  becomes overcharged, the discharge resistor  31  turns the switching element to the on-state. The discharge resistor  31  is thereby supplied with power from the battery cells in the overcharged state and converts the power to thermal energy to generate heat. 
         [0044]    A thermal coupling agent such as a thermal grease  32  intervenes between the cover surface  8  of the metal cover  4  and the discharge resistor  31 . Specifically, the metal cover  4  has a shape forming a predetermined gap between the cover surface  8  and the discharge resistor  31  and the thermal grease  32  is applied on the discharge resistor  31 . This brings the metal cover  4  into thermal contact with the discharge resistor  31  and causes the metal cover  4  to receive the heat from the discharge resistor  31 . 
         [0045]    As shown in  FIG. 3 , a cell voltage sensor board  7   a  included in the voltage detecting device  1  includes a power supply circuit  21   a,  an integrated circuit  30   a,  a direct current (DC)/DC converter  40   a,  and an insulating element  50   a.    
         [0046]    The power supply circuit  21   a  included in the cell voltage sensor board  7   a  generates a voltage to be supplied to a power supply of a level converter (analog conversion circuit) that employs the lowest potential of the battery cell group  12   a  as a reference potential Va and is included in the integrated circuit  30   a.  For example, the power supply circuit  21   a  boosts the voltage of the battery cell group  12   a  to generate the supply voltage of the analog conversion circuit, whose reference potential is Va. 
         [0047]    Each of the battery cell groups  12   a,    12   b,  and  12   c  is composed of plural battery cells. 
         [0048]    The integrated circuit  30   a  includes the level converter  301   a  and an analog to digital (A/D) conversion circuit  302   a.    
         [0049]    The level converter  301   a  converts the cell voltage of each battery cell in the battery cell group  12   a  so that the maximum voltage output by the plural battery cells may become the voltage corresponding to the full scale of the A/D conversion circuit  302   a.  The level converter  301   a  operates by a power supply of a high voltage (e.g. 60 volts) for input of the voltage of the battery cell group  12   a.    
         [0050]    The cell voltage after the conversion by the level converter  301   a  is input to the A/D conversion circuit  302   a  and the A/D conversion circuit  302   a  generates a corresponding digital signal. The A/D conversion circuit  302   a  operates by a power supply (second power supply) of a low voltage (e.g. five volts). 
         [0051]    The DC/DC converter  40   a  generates a voltage to be supplied to the power supply of the A/D conversion circuit (digital conversion circuit)  302   a  included in the integrated circuit  30   a.  For example, the DC/DC converter  40   a  generates a voltage of five volts with respect to the reference potential Va on the basis of a pulse width modulation (PWM) signal (pulse signal) generated by the processor (control unit)  80 . The DC/DC converter  40   a  includes the first communicating element  25  and the second communicating element  26 . 
         [0052]    The insulating element  50   a  transmits, to the processor  80 , information indicating the voltage of the battery cell converted by the integrated circuit  30   a  without exchange of current between the cell voltage sensor board  7   a  and the battery ECU board  6 . 
         [0053]    A cell voltage sensor board  7   b  has the same functional units as those of the cell voltage sensor board  7   a  except for that the reference potential is Vb. Specifically, the cell voltage sensor board  7   b  includes a power supply circuit  21   b,  an integrated circuit  30   b,  a DC/DC converter  40   b,  and an insulating element  50   b.    
         [0054]    Similarly, a cell voltage sensor board  7   c  has the same functional units as those of the cell voltage sensor board  7   a  except for that the reference potential is Vc. Specifically, the cell voltage sensor board  7   c  includes a power supply circuit  21   c,  an integrated circuit  30   c,  a DC/DC converter  40   c,  and an insulating element  50   c.    
         [0055]    The battery ECU board  6  includes the DC/DC converters  40   a,    40   b,    40   c,  . . . , the insulating elements  50   a,    50   b,    50   c,  . . . , a power supply  60 , a power supply circuit  70 , and the processor  80 . 
         [0056]    The power supply  60  outputs a voltage to the power supply circuit  70 . For example, the power supply  60  outputs a voltage of 12 volts to the power supply circuit  70 . 
         [0057]    The power supply circuit  70  generates the supply voltage used for the operation of the processor  80  on the basis of the voltage output by the power supply  60 . For example, the power supply circuit  70  generates a voltage of five volts from the voltage of 12 volts output by the power supply  60 . 
         [0058]    The processor  80  generates the PWM signal for the generation of the supply voltage of the A/D conversion circuit  302   a  by the DC/DC converter  40   a . Furthermore, the processor  80  acquires information on the voltage of each battery cell converted by the A/D conversion circuit  302   a  via the insulating element  50   a.  The processor  80  may generate a command signal to prescribe the timing of sampling of the cell voltage of each voltage cell by the A/D conversion circuit  302   a.    
         [0059]    According to the above-described configuration, by employing wireless communications as communications between the integrated circuit  30  and the processor  80 , wiring between the cell voltage sensor board  7  and the battery ECU board  6  can be omitted and thus the configuration of the voltage detecting device  1  can be further simplified. 
         [0060]    Furthermore, even when the number of cell voltage sensor boards  7  configuring the battery B is changed, responding to the change is allowed more easily through increase or decrease in the cell voltage sensor board  7 . 
         [0061]    Furthermore, by attaching the battery ECU board  6  and the cell voltage sensor boards  7  to the locating pins  11  of the base part  9 , the battery ECU board  6  and the cell voltage sensor boards  7  are disposed in parallel to each other. In addition, the first communicating element  25  and the second communicating element  26  are disposed opposed to each other. This enables wireless communications between the first communicating element  25  and the second communicating element  26 , which can reduce the size of the voltage detecting device  1  as a unit having the battery ECU board  6  and the cell voltage sensor boards  7 . 
         [0062]    Moreover, by employing the configuration in which the discharge resistor  31  is mounted on the cell voltage sensor board  7  and the discharge resistor  31  is connected to the metal cover  4  by the thermal grease  32 , heat generated from the cell voltage sensor board  7  is transferred not to the battery ECU board  6  but to the metal cover  4  and thus the heat resistance of the voltage detecting device  1  can be improved. 
         [0063]    In the above embodiment, the cores  27  and the coils  28  are used as the communicating elements. However, the communicating elements are not limited thereto as long as they can be mounted on boards and enable wireless communications. For example, it is also possible to employ, as the communicating elements, antennas such as microstrip antennas (patch antennas) or communicating elements such as a light emitting element and a light receiving element. 
       Second Embodiment 
       [0064]    As shown in  FIG. 4 , a resin cover  34  intervenes between the battery ECU board  6  and the cell voltage sensor board  7  in a voltage detecting device  1 B of a second embodiment of the present disclosure. The resin cover  34  is attached to the resin case  3 , to which the battery ECU board  6  is attached, in such a manner as to cover the battery ECU board  6  by using fastening measures such as bolts. 
         [0065]    The cell voltage sensor board  7  is supported by a second support surface  37  of a second support part  36  made in the resin cover  34  and the wall part  10  of the resin case  3 , and at least part of the cell voltage sensor board  7  is fixed to the second support surface  37  by using fastening measures such as bolts. The second support surface  37  and the wall part  10  are so formed that the attached cell voltage sensor board  7  is disposed in parallel to the battery ECU board  6 . 
         [0066]    The resin cover  34  is so formed that the board housing space  5  is divided into a first board housing space  5   a  and a second board housing space  5   b  by attaching the resin cover  34  to the resin case  3  and then attaching the metal cover  4 . The battery ECU board  6  is housed in the first board housing space  5   a  formed by the resin case  3  and the resin cover  34 . The cell voltage sensor board  7  is housed in the second board housing space  5   b  formed by the resin cover  34  and the metal cover  4 . 
         [0067]    The resin cover  34  has a resin cover main body  35  that has a plate shape and is disposed in parallel to the base part  9  of the resin case  3  and the battery ECU board  6  by attaching the resin cover  34  to the resin case  3 . The resin cover main body  35  is so formed that the interval between the battery ECU board  6  and the resin cover main body  35  is substantially the same as that between the cell voltage sensor board  7  and the resin cover main body  35 . The thickness of the resin cover main body  35  is set as appropriate depending on the communicable distance between the communicating elements  25  and  26 , the degree of heat generation of each board, the dimensions of the voltage detecting device  1 B, and so forth. 
         [0068]    Due to the formation of the resin cover  34  in this manner, the resin cover main body  35  functioning as an insulating resin is disposed between the first communicating element  25  and the second communicating element  26  of the present embodiment. 
         [0069]    According to the above embodiment, due to the placement of the resin cover main body  35  functioning as an insulating resin between the battery ECU board  6  and the cell voltage sensor board  7 , the cell voltage sensor board  7  and the battery ECU board  6  can be thermally separated from each other. By separating the cell voltage sensor board  7 , on which the discharge resistor  31  configured to generate heat is mounted, from the battery ECU board  6 , the temperature range in which the operation of parts such as a processor mounted on the battery ECU board  6  is ensured can be narrowed. That is, employing more inexpensive parts is allowed and cost reduction of the voltage detecting device  1 B can be achieved. Furthermore, performance such as the detection accuracy can be enhanced by narrowing the temperature range in which the operation of parts such as the processor is ensured. 
         [0070]    Although embodiments of the present disclosure are described in detail above with reference to the drawings, the respective configurations in the respective embodiments, combinations thereof, and so forth are one example and addition, omission, replacement, and other changes of the configurations can be made without departing from the gist of the present disclosure. Furthermore, the present disclosure is not limited by the embodiments and is limited only by the scope of claims.