Patent Publication Number: US-2017352495-A1

Title: Capacitor module

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national stage of PCT/JP2015/085650 filed Dec. 21, 2015, which claims priority of Japanese Patent Application No. JP 2015-002101 filed Jan. 8, 2015. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a capacitor module. 
     BACKGROUND 
     Conventionally, various load apparatuses installed in a vehicle operate based on electric power that can be supplied from a battery. Operation of each load apparatus is not guaranteed when there is a power failure due to a battery failure, a reduction in voltage, or the like. Therefore, a backup power supply apparatus having a power storage member such as a large-capacity capacitor has been proposed. The large-capacity capacitor can be housed in a case fixed to a circuit board, and mounted on the circuit board (see, for example, JP 2009-253009A). 
     Incidentally, various electronic components can be mounted on a circuit board. However, as described above, when a case housing a large-capacity capacitor is fixed on the circuit board, the arrangement of electronic components is restricted by the case. Such arrangement restriction leads to an increase in the size of the circuit board, which in turn leads to an increase in the size of a module that houses the circuit board. 
     An object of the present invention is to reduce the size of a capacitor module. 
     A capacitor module according to one aspect of the present invention includes: a module case including a lower case and an upper case; a housing case fixed to an inner face of the upper case; a capacitor housed in the housing case; a circuit board fixed to an upper face of the lower case, the circuit board having wiring electrically connectable to the capacitor, and electronic components constituting a circuit that controls electric current to the capacitor being mounted to the circuit board; and an external connection connector fixed to the lower case and including a terminal connected to wiring of the circuit board. 
     According to this configuration, the housing case that houses the capacitor is fixable to the upper case of the module case. Also, the circuit board to which the capacitor is connectable is fixable to the lower case of the module case. Therefore, because the circuit board and the housing case are separated from each other, electronic components can be mounted in a region where the circuit board and the housing case overlap in a plan view, and therefore, the size of the circuit board and the module case can be reduced. 
     In the above capacitor module, it is preferable that the upper case has an upper plate that fixedly supports the housing case, a side plate extending from an end portion of the upper plate in a direction orthogonal to the upper plate, and a terminal holding plate fixed to the side plate and holding a terminal of the capacitor. 
     According to this configuration, the capacitor can be housed in the housing case fixed to the upper plate of the upper case. A terminal of the capacitor can be fixed to a side plate extending from the upper plate in a direction orthogonal to the upper plate. Therefore, the terminal of the capacitor is less likely to move relative to the upper case. 
     In the above capacitor module, it is preferable that the capacitor has a capacitor body that can be housed in the housing case, and a lead wire that protrudes from the capacitor body, and the circuit board has a connection hole where the lead wire of the capacitor can be electrically connected. 
     According to this configuration, the capacitor held in the upper case has a capacitor body that can be housed in the housing case and a lead wire that protrudes from the capacitor body. The lead wire can be electrically connected to the connection hole formed in the circuit board. 
     In the above capacitor module, it is preferable that the lead wire of the capacitor has a press-fit terminal having a press-in portion that is wider than an inner diameter of the connection hole at its tip and is elastically deformable, and the press-in portion of the press-fit terminal is pressed into the connection hole of the circuit board. 
     According to this configuration, the lead wire has a press-fit terminal at its tip, and the press-fit terminal is pressed into the connection hole of the circuit board, so the capacitor is easily connected to the circuit board. 
     In the above capacitor module, it is preferable that the press-fit terminal has an attachment portion that protrudes in a direction orthogonal to the lead wire, and the terminal holding plate is arranged closer to the capacitor body side than the attachment portion, and holds the press-fit terminal. 
     According to this configuration, the press-fit terminal has an attachment portion, and the terminal holding plate fixed to the upper case can be arranged closer to the capacitor body side than the attachment portion. By the terminal holding plate engaging with the attachment portion, the press-fit terminal can be pressed into the connection hole. 
     In the above capacitor module, it is preferable that the electronic component includes an electronic component mounted on a lower case side mounting face of the circuit board, and an electronic component mounted on a capacitor side mounting face opposite to the lower case side mounting face of the circuit board, the heating quantity of the electronic component mounted on the lower case side mounting face being larger than the heating quantity of the electronic component mounted on the capacitor side mounting face. 
     According to this configuration, electronic components can be mounted on both sides of the circuit board, and electronic components with a larger heating quantity can be mounted on the face of the lower case side. Therefore, heat of the electronic components is less likely to be transferred to the capacitor, and a temperature increase of the capacitor is suppressed. 
     In the above capacitor module, it is preferable that the housing case and the circuit board face each other with an open space therebetween, and at least one of the electronic components faces the housing case in the open space. 
     According to this configuration, it is possible to reduce the footprint of the circuit board, and it is possible to reduce the size of the module case. 
     According to the present invention, it is possible to reduce the size of the capacitor module. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a partial side cross-sectional view of a capacitor module of an embodiment. 
         FIG. 2  is a partial cross-sectional view for describing assembly of a lower case and an upper case of the capacitor module. 
         FIG. 3  is a plan view of the capacitor module. 
         FIG. 4  is a perspective view of capacitors and a housing case. 
         FIG. 5  is an exploded perspective view of a module case. 
         FIG. 6  illustrates a press-fit terminal. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Following is a description of a capacitor module of an embodiment. Note that in the accompanying drawings, there are cases where constituent elements are shown enlarged for easy understanding. Also, there are cases where the dimensional proportions of the constituent elements differ from actual elements or from those in other drawings. 
     As shown in  FIG. 1 , the capacitor module includes a module case  10 , a circuit board  20  housed in the module case  10 , and a plurality of capacitors  30 . The capacitors  30  are, for example, electric double layer capacitors. 
     The module case  10  is formed in a substantially rectangular parallelepiped shape. The module case  10  is made of synthetic resin, for example. The module case  10  can include an unshown attachment portion for attaching the module case  10  to a vehicle. 
     The module case  10  includes a lower case  11 , and an upper case  12  attachable to the lower case  11 . As shown in  FIG. 5 , the lower case  11  has a rectangular plate-like base plate  11   a  and side plates  11   b,    11   c,  and  11   d  standing at end portions of the base plate  11   a.  A through hole  11   e  is formed in the side plate  11   c,  and an external connection connector  13  shown in  FIG. 1  is attachable at the through hole  11   e.    
     The upper case  12  has an upper plate  12   a  and a side plate  12   b,  and can be a substantially L-shaped cover. The upper case  12  is attached to the lower case  11 , for example, by snap-fitting, and defines an internal space of the module case  10 . 
     As shown in  FIG. 2 , the circuit board  20  is attached to the base plate  11   a  of the lower case  11 . The circuit board  20  is supported apart from the base plate  11   a  by support columns  25  between the circuit board  20  and the base plate  11   a  of the lower case  11 , and fixed to the lower case  11  by screws  26  used as fixing members. The length of the support columns  25 , that is, the distance between the base plate  11   a  of the lower case  11  and the circuit board  20 , is set according to electronic components to be mounted on the circuit board  20 . 
     A lead  13   a  of the external connection connector  13  is connected by, for example, soldering to the circuit board  20 . 
     A plurality of electronic components  21   a  and  21   b  are mounted on the circuit board  20 . The electronic components  21   a  and  21   b  constitute a control circuit that controls charging current and discharging current for the capacitors  30 . 
     The electronic components  21   a  mounted on the upper face (also referred to as a capacitor side mounting face) of the circuit board  20  are microcomputers logic ICs, small-signal system transistors, or the like. These electronic components  21   a  have low power consumption and generate little heat. 
     The electronic components  21   b  mounted on the lower face (also referred to as a lower case side mounting face) of the circuit board  20  are switching elements such as MOS transistors, elements constituting a snubber circuit, rectifier diodes, bypass capacitors, or the like. These electronic components  21   b  generate much heat. 
     In the upper case  12 , a housing case  40  is fixed to the lower face of the upper plate  12   a,  and a plurality of the capacitors  30  are housed in the housing case  40 . 
     As shown in  FIG. 3 , four of the capacitors  30  are housed in the housing case  40 . 
     A capacitor  30  has a capacitor body  31  and a pair of lead wires  32 . The capacitor body  31  is formed in, for example, a cylindrical shape, and houses an electric storage element. 
     As shown in  FIG. 4 , the housing case  40  is formed in a substantially rectangular parallelepiped shape. On an upper face  40   a  of the housing case  40 , a plurality of (four in  FIG. 4 ) engaging portions  41  are formed protruding from the upper face  40   a.  As shown in  FIG. 5 , a plurality (four in  FIG. 5 ) of corresponding insertion holes  12   c  are formed in the upper plate  12   a  of the upper case  12 . As shown in  FIG. 1 , the engaging portions  41  of the housing case  40  are inserted into the insertion holes  12   c  of the upper case  12  (the upper plate  12   a ). The engaging portions  41  are, for example, snap-fit portions, and engage with the upper plate  12   a  to fix the housing case  40  to the upper case  12  (the upper plate  12   a ). In this way, the housing case  40  housing the capacitors  30  can be integrated with the upper case  12  (the upper plate  12   a ). 
     As shown in  FIG. 3 , a plurality (four) of housing holes  42  corresponding to the number of capacitors  30  to be housed are formed in the housing case  40 . 
     As shown in  FIG. 4 , the housing holes  42  are formed in a cylindrical shape corresponding to the shape of the capacitor bodies  31 , and hold the inserted capacitor bodies  31 . In this drawing, a capacitor corresponding to one housing hole  42  is omitted. For example, the housing case  40  has ribs (not shown) arranged in the circumferential direction on the inner face of the housing holes  42 . The ribs are formed so as to extend in the insertion direction of the capacitors  30 . The diameter of a circle connecting apexes of the plurality of ribs is set to be slightly smaller than the diameter of a capacitor body  31 . Therefore, a capacitor body  31  that has been inserted into a housing hole  42  is held by the housing case  40 . 
     As shown in  FIG. 2 , the lead wires  32  of a capacitor  30  are led out from a circular end face of the capacitor body  31  in a direction orthogonal to this end face. Further, the pair of lead wires  32  are formed bent in an L shape in a side view so as to extend toward the circuit board  20 . The lead wires  32  are supported by an attachment portion  14  formed on an inner face  12   d  of the side plate  12   b  of the upper case  12 , and a terminal holding plate  15  fixed to the attachment portion  14 . 
     As shown in  FIG. 3 , slits  15   a  into which the lead wires  32  are inserted are formed in the terminal holding plate  15 . The terminal holding plate  15  with the lead wires  32  inserted into the slits  15   a  is fixed to the attachment portion  14 , for example, by snap-fitting. Note that the terminal holding plate  15  may also be fixed to the attachment portion  14  using, for example, an adhesive, welding, screws, or the like. 
     As shown in  FIG. 2 , connection holes  22  where the pairs of lead wires  32  of the plurality of capacitors  30  are respectively connected are formed in the circuit board  20 . The connection hole  22  is a through hole having conductivity and has an electric conductor such as metal plating formed on its inner face, and electrically connects a pattern on the circuit board  20  to the lead wires  32 . 
     As shown in  FIG. 6 , a lead wire  32  has a press-fit terminal  33  at its tip. The press-fit terminal  33  has, in order from the tip, a guide portion  33   a , a press-in portion  33   b,  and an attachment portion  33   d.  The guide portion  33   a  is formed in a narrow-tipped (tapered) shape with a narrow tip. The guide portion  33   a  facilitates the insertion of the lead wire  32  into the connection hole  22  of the circuit board  20  shown in  FIG. 2 . 
     The press-in portion  33   b  protrudes in a direction orthogonal to the length direction (the vertical direction in  FIG. 6 ). The width of the press-in portion  33   b  is greater than the inner diameter of the connection hole  22  of the circuit board  20  shown in  FIG. 2 . At the center of the press-in portion  33   b,  a window portion  33   c  extending in the length direction is formed. The window portion  33   c  enables deformation such that the press-in portion  33   b  is elastically reduced in diameter. 
     The attachment portion  33   d  protrudes outward on both sides in a direction orthogonal to the extending direction of the press-fit terminal  33  (the axial direction of the press-fit terminal  33 , and the vertical direction in  FIG. 6 ). The attachment portion  33   d  is formed in, for example, a rectangular shape. The attachment portion  33   d  engages with the terminal holding plate  15 , and presses the press-in portion  33   b  of the press-fit terminal  33  at the time of connection into the connection hole  22  (see  FIG. 2 ). 
     Next, operation of the above capacitor module will be described. 
     As shown in  FIG. 1 , the housing case  40  that houses the capacitor  30  is fixable to the upper case  12  of the module case  10 . The circuit board  20  to which the capacitor  30  is connectable is fixable to the lower case  11  of the module case  10 . Therefore, because the circuit board  20  and the housing case  40  are separated from each other, the electronic components  21   a  can be mounted in a region where the circuit board  20  and the housing case  40  overlap in a plan view. Therefore, the surface area of the circuit board  20  where the electronic components  21   a  are mountable can be reduced. Also, it is possible to achieve a reduction in the surface area of the module case  10  that houses the circuit board  20 , that is, the surface area required for fixing the capacitor module. 
     The capacitor  30  can be housed in the housing case  40  fixed to the upper plate  12   a  of the upper case  12 . The terminals of the capacitor  30  are fixable to the side plate  12   b  extending from the upper plate  12   a  in the direction orthogonal to the upper plate  12   a.  Therefore, relative movement of the lead wires  32  of the capacitor  30  with respect to the upper case  12  is prevented or reduced. Relative movement of the lead wires  32  of the capacitor  30  causes disconnection of the lead wires  32  or poor connection with the circuit board. Therefore, by suppressing the relative movement of the lead wires  32 , occurrence of defects is suppressed. 
     The capacitor  30  held by the upper case  12  has the capacitor body  31  that can be housed in the housing case  40  and the lead wires  32  that protrude from the capacitor body  31 . The lead wires  32  are electrically connectable to the connection holes  22  formed in the circuit board  20 . The charging current and discharging current for the capacitor  30  are controlled by a control circuit constituted by the electronic components  21   a  and  21   b  mounted on the circuit board  20 . 
     Each lead wire  32  has a press-fit terminal  33  at its tip, and the press-fit terminal  33  is pressed into the connection hole  22  of the circuit board  20 , and thus the capacitor  30  is easily connected to the circuit board  20 . 
     The press-fit terminal  33  has the attachment portion  33   d,  and the terminal holding plate  15  fixed to the upper case  12  can be arranged closer to the capacitor body  31  side than the attachment portion  33   d.  The terminal holding plate  15  engages with the attachment portion  33   d  to restrict movement of the press-fit terminal  33 , and thus the press-fit terminal  33  is pressed into the connection hole  22 . 
     The electronic components  21   a  and  21   b  can be mounted on both faces of the circuit board  20 , and the electronic components  21   b , which have a larger heating quantity, can be mounted on the face of the side of the lower case  11 . Therefore, the heat of the electronic components  21   b  is less likely to be transferred to the capacitor  30 , and a temperature increase of the capacitor  30  is suppressed. 
     As described above, according to the present embodiment, the following effects are exhibited. 
     (1) The capacitor module has the module case  10  composed of the lower case  11  and the upper case  12 . The housing case  40  is fixable to the inner face of the upper case  12 , and the capacitor  30  can be housed in the housing case  40 . The circuit board  20  is fixed to the upper face of the lower case  11 . The circuit board  20  has wiring electrically connectable to the capacitor  30 , and the electronic components  21   a  and  21   b  constituting a circuit that controls current to the capacitor  30  are mounted on the circuit board  20 . Also, the circuit board  20  is connectable to an apparatus (for example, a brake control apparatus or the like) outside the module through the external connection connector  13  fixed to the lower case  11 . 
     The housing case  40  that houses the capacitor  30  is fixable to the upper case  12  of the module case  10 . The circuit board  20  to which the capacitor  30  is connectable is fixable to the lower case  11  of the module case  10 . Therefore, because the circuit board  20  and the housing case  40  are separated from each other, the electronic components  21   a  can be mounted in a region where the circuit board  20  and the housing case  40  overlap in a plan view, and thus the size of the circuit board  20  and the module case  10  can be reduced. Also, it is possible to achieve a reduction in the surface area of the module case  10  that houses the circuit board  20 , that is, the surface area required for fixing the capacitor module. 
     (2) The capacitor  30  can be housed in the housing case  40  fixed to the upper plate of the upper case  12 . The terminal of the capacitor  30  is fixable to a side plate extending from the upper plate in a direction orthogonal to the upper plate. Therefore, the terminal of the capacitor  30  is less likely to move relative to the upper case  12 . In the capacitor  30 , relative movement of the lead wires  32  causes disconnection of the lead wires  32  or poor connection with the circuit board. Therefore, by suppressing the relative movement of the lead wires  32 , occurrence of defects can be suppressed. 
     (3) The capacitor  30  held by the upper case  12  has the capacitor body  31  that can be housed in the housing case  40 , and lead wires protruding from the capacitor body  31 . The lead wires are electrically connectable to the connection holes formed in the circuit board  20 . The charging current and discharging current for the capacitor  30  can be controlled by a control circuit constituted by the electronic components  21   a  and  21   b  mounted on the circuit board  20 . 
     (4) Each lead wire  32  has a press-fit terminal at its tip, and the press-fit terminal is pressed into the connection hole of the circuit board  20 . Therefore, the capacitor  30  can be easily connected to the circuit board  20 . Connection of the capacitor  30  to the circuit board  20  is performed at the time of assembling the lower case  11  and the upper case  12 . That is, because the capacitor  30  is connected to the circuit board  20  at the same time as assembling the upper case  12  to the lower case  11 , a step of connecting the capacitor  30  to the circuit board  20  is unnecessary, and so it is possible to reduce the number of manufacturing steps, the amount of time for manufacturing, and the like. 
     (5) The press-fit terminal  33  has the attachment portion  33   d,  and the terminal holding plate  15  fixed to the upper case  12  can be arranged closer to the capacitor body  31  side than the attachment portion  33   d.  The terminal holding plate  15  engages with the attachment portion  33   d  to restrict movement of the press-fit terminal  33 , and thus the press-fit terminal  33  can be reliably pressed into the connection hole  22 . 
     (6) The electronic components  21   a  and  21   b  can be mounted on both faces of the circuit board  20 , and the electronic components  21   b  with a large heating quantity can be mounted on the face on the side of the lower case  11 . Therefore, heat of the electronic components  21   b  is less likely to be transferred to the capacitor  30 , so a temperature increase of the capacitor  30  can be suppressed. A temperature increase of the capacitor  30  lowers properties and its useful life. Therefore, by mounting the electronic components  21   b  in this manner, it is possible to suppress a reduction in the performance of the capacitor  30 , and achieve a longer life. 
     (7) The housing case  40  and the circuit board  20  are arranged between the top plate and the bottom plate (that is, between the upper plate  12   a  of the upper case  12  and the base plate  11   a  of the lower case  11 ) of the module case  10 . The housing case  40  and the circuit board  20  face each other with an open space (empty space) therebetween. At least one electronic component  21   a  mounted on the circuit board  20  faces the housing case  40  in the open space (see  FIG. 1 ). According to this configuration, the footprint of the circuit board  20  can be reduced, and the size of the module case  10  can be reduced. 
     Note that the embodiment may also be modified as follows. 
     In the above embodiment, the number of capacitors  30  is four, but the number of capacitors may be appropriately changed to three or less, or five or more. 
     In the above embodiment, the housing case  40  is integrally fixed to the upper case  12  by the engaging portions  41  of the upper face  40   a  of the housing case  40 , but the method of fixing the housing case  40  is not limited to this method. For example, an engaging portion of the side plate  12   b  of the upper case  12  and an engaging portion of a side face of the housing case  40  may be fixed by snap-fitting. Also, the housing case  40  may be fixed to the upper case  12  by screws (bolts and nuts) or the like. 
     The housing case  40  is not limited to being divided into the cases  11  and  12  of the shape shown in the drawings, and may also be divided in various ways. For example, the housing case  40  may also be equally or unequally divided in the vertical direction in  FIG. 1 . 
     The present invention is not limited to the exemplary configuration disclosed above. For example, the exemplary disclosed features should not be interpreted as being essential to the present invention, and the subject matter of the present invention may also exist in fewer features than all of the features of the specific embodiment that was disclosed.