Abstract:
Depending on the orientation by which a breathing filter is mounted in a vehicle, water can accumulate in the breathing filter, and prevent the pressure difference between the space inside a case and the outside air from being adjusted; therefore, the vehicular layout is limited. Also, because the filter is formed in the center of the case, electronic parts cannot be installed on substrates on the upper and lower surfaces of the filter, meaning that the substrate size and the case size will increase. In addition, the costs will increase. The structure of the present invention is characterized in that breathing paths are provided on the surfaces sandwiching a portion where a filter film is welded in the corner of a resin-side case of a vehicle-mounted electronic control device such as an engine control unit or an automatic transmission control unit, and in that the breathing paths are connected inside.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a case structure for an electronic control device mounted on a vehicle, such as an engine control unit or an automatic transmission control unit, which has a waterproof structure provided with a breathing filter. 
       BACKGROUND ART 
       [0002]    An electronic control device, such as an engine control unit or an automatic transmission control unit, which is mounted under a condition where the unit is directly splashed with liquid such as water, for example, mounted in an engine room, is configured to have a circuit board mounted with electronic parts housed in a protective space (waterproofed space) in a case made up of a plurality of case parts joined. In such an electronic control device, completely sealing a case causes stress to be applied to a harness connected to a connector portion and a waterproof portion at the tip of the harness due to a pressure difference between the inside of the case and the outside air, resulting in making liquid such as water be liable to be drawn into the unit. Therefore, a structure has been provided in which a breathing path is provided at a part of a case member and a breathing filter film having permeability and waterproofness is attached to an end surface of the breathing path (e.g. PTL 1). 
       CITATION LIST 
     Patent Literature 
       [0003]    PTL 1: JP 2006-49618 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    However, in a conventional structure of an electronic control device, depending on a direction in which the device is mounted on a vehicle, water stays in a breathing filter portion to disable adjustment of a pressure difference between the inside of a case and the outside air, resulting in limiting a vehicular layout. Additionally, since a filter portion is formed in the central part within the case, no electronic part can be mounted on boards below and above the filter portion, resulting in increasing a board size and a case size. Additionally, a cost-up problem is also involved. 
         [0005]    Therefore, an object of the present invention is to provide an electronic control equipment less limited than a conventional equipment in terms of an equipment mounting direction. 
       Solution to Problem 
       [0006]    The above-described problem is solved by the invention recited in Claims. 
         [0007]    For example, breathing paths are provided in surfaces that sandwich a part to which a filter film is welded at a corner portion of a resin-side case of an electronic control device, and these paths are connected to each other inside the case. 
       Advantageous Effects of Invention 
       [0008]    The present invention enables provision of an electronic control equipment less limited than a conventional equipment in terms of an equipment mounting direction. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1  shows an external view, and an expanded view and sectional views of a relevant part of an electronic control device according to Example 1. 
           [0010]      FIG. 2  shows an expanded view and a sectional view of a relevant part in a filter portion according to Example 2. 
           [0011]      FIG. 3  shows an expanded view and a sectional view of a relevant part in a filter portion according to Example 2. 
           [0012]      FIG. 4  shows an expanded view and a sectional view of a relevant part in a filter portion according to Example 4. 
           [0013]      FIG. 5  shows an expanded view and sectional views of a relevant part in a filter portion according to Example 5. 
           [0014]      FIG. 6  shows an external view, and an expanded view and a sectional view of a relevant part of an electronic control device according to Example 6. 
           [0015]      FIG. 7  shows an expanded view and sectional views of a relevant part in a filter portion according to Example 7. 
           [0016]      FIG. 8  shows expanded views and a sectional view of a relevant part in a filter portion according to Example 8. 
           [0017]      FIG. 9  shows expanded views and a sectional view of a relevant part in a filter portion according to Example 9. 
           [0018]      FIG. 10  is a sectional view showing that in a con figuration including a metal cover and a resin base, an electronic part and the like can be mounted above a filter portion. 
           [0019]      FIG. 11  is a sectional view showing that in a configuration including a resin, cover and a metal base, an electronic part and the like can be mounted above a filter portion. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0020]    In the following, Examples of the present invention will be described with reference to  FIG. 1  to  FIG. 4 .  FIG. 1  shows an external view and developed views of an electronic control device mounted on a vehicle, such as an engine control unit or an automatic transmission control unit, which adopts a structure of the present Example. A view on arrow A is an expanded view of a filter portion seen from the outside, the filter portion being provided at a corner portion of a resin base. Additionally, the sectional views show sections of parts taken along line B-B, line C-C and line D-D, respectively.  FIG. 2  to  FIG. 5  are expanded views of filter portions seen from the outside, the filter portions having configurations different from each other.  FIG. 6  shows an example of an electronic control device having a configuration including a metal base and a resin cover, and shows views of a configuration in which the resin cover is provided with a filter portion. 
         [0021]    A view on arrow J is an expanded view of a filter portion seen from the outside, the filter portion being provided at a corner portion of the resin cover. The sectional view is a part of the section taken along line K-K.  FIG. 7  to  FIG. 9  are expanded views of filter portions seen from the outside, the filter portions having configurations different from each other.  FIG. 10  and  FIG. 11  are sectional views showing the effect of the present invention that parts can be mounted also on a board below a filter portion. 
       Embodiment 1 
       [0022]      FIG. 1  shows First Example of the present invention. 
         [0023]    In the present Example, between an electronic part  4   a  mounted on a circuit board  4  and a metal cover  2  (die-cast), a heat conductive material  4   b  is interposed, and the circuit board  4  is fixed to the metal cover  2  by a circuit board fixing screw  6 . For maintaining waterproofness of a case, with an adhesive  5  interposed among a connector for external connection  1 , the metal cover  2  and a resin base  3 , the metal cover  2  and the resin base  3  are joined at heat caulking portions  3   a  obtained by thermally molding bosses provided at corner parts of the resin base  3 . The metal cover  2  and the resin base  3  may be joined by other method such as using a screw or a rivet. At a corner portion of the resin base  3 , a breathing filter film  7  is provided. The filter may be provided at any corner portion. Methods of attaching the filter film  7  to the resin base  3  include heat-welding, bonding with an adhesive, adhesion by an adhesive tape, integral molding with the resin base  3 , and the like. Breathing paths  8  are opened in surfaces sandwiching a filter portion at the corner portion (breathing path opening surfaces  9 ) and are connected to each other inside. Below the filter film  7 , a breathing hole  11  is provided to communicate with the breathing path  8 . In this case, an attachment position of the filter film  7  is set based on a positional relationship between the breathing path  8  and the breathing hole  11  so as not to be seen from the outside in order to prevent high pressure water from splashing the filter film  7 . Since the filter film  7  and the breathing path  8  are thin relative to a thickness of the case, the filter portion can be configured to be thin as a whole. Therefore, as shown in  FIG. 10 , a clearance with the circuit board  4  can be made large to enable the electronic part  4   a  to be mounted above the filter portion. 
       Embodiment 2 
       [0024]      FIG. 2  shows Second Example of the present invention. As compared with the above Example 1, at least one rib  10  is formed in a breathing path  8  in order to ensure strength. It is necessary to provide the rib  10  because as an opening area of the breathing path  8  is increased, the strength of the filter portion is decreased. In addition to ensuring the strength, the rib  10  serves also as a protective wall for preventing high pressure water from splashing a filter film  7 . Similarly to Example 1, since, the filter portion has a small thickness, parts can be mounted also on the board above the filter portion. 
       Embodiment 3 
       [0025]      FIG. 3  shows Third Example of the present invention. As compared with the above Example  2 , a rib has a different shape. Similarly to Example 1, the filter has a small thickness to enable parts to be mounted also on the board above the filter portion. Additionally, an opening area of a breathing path  8  of a resin base  3  is decreased to suppress an inflow of high pressure water. Further, since a rib  10  is angled, the force of inflowing high pressure water, which hits against a wall surface, is dispersed to reduce a pressure applied to a breathing filter film  7 . 
       Embodiment 4 
       [0026]      FIG. 4  shows Fourth Example of the present invention. As compared with the above Examples 1 to 3, the insides of breathing paths formed in respective surfaces sandwiching a filter-portion are angled to cross with each other within a base in order to improve drainability. Similarly to Example 1 to Example 3, the filter has a small thickness to enable parts to be mounted also on a board above the filter portion. Additionally, having an angle  12  facilitates discharging of entering high pressure water at whichever angle the electronic control device of the present invention is arranged. 
       Embodiment 5 
       [0027]      FIG. 5  shows Fifth Example of the present invention. As compared with the above Example 1 to Example 4, a bottom surface of a breathing path of a resin base  2  has a slanting portion  13  in order to improve drainability. In this case, a filter film  7  is set based on a positional relationship between breathing paths  8  and a breathing hole  11  so as not to be seen from the outside in order to prevent high pressure water from, splashing the filter film  7 . Similarly to Example 1 to Example 4, the filter portion has a small thickness to enable parts to be mounted also on a board above the filter portion. 
       Embodiment 6 
       [0028]      FIG. 6  shows Sixth Example of the present invention. As-compared with the above Example 1, a resin cover  14  and a metal base  15  are used. In the present Example, between an electronic part  4   a  mounted on a circuit board  4  and the metal base  3 , a heat conductive material  4   b  is interposed, and the circuit board  4  is fixed to the metal base  15  by a circuit board fixing screw  6 . For maintaining waterproofness of a case, with an adhesive  5  interposed among a connector for external connection  1 , the resin cover  14  and the metal base  15 , the cover and the base are joined by heat caulking bosses provided at the four corners of the resin cover  14 . The resin cover  14  and the metal base  15  may be fixed by other method such as using a screw or a rivet. In this case, at the corner portion of the resin cover  14 , a filter film  7  is provided. The filter may be provided at any corner portion. Methods of attaching the filter film  7  to the resin cover  14  include heat-welding, bonding with an adhesive, adhesion by an adhesive tape, integral molding with the resin cover  14 , and the like. Breathing paths  8  are opened in surfaces sandwiching a filter portion at the corner portion and are connected to each other inside. Below the filter film  7 , a breathing hole  11  is provided to communicate with the breathing path  8 . In this case, the filter film  7  is set based on a positional relationship between the breathing path  8  and the breathing hole  11  so as not to be seen from the outside in order to prevent high pressure water from splashing the filter film  7 . Since the filter film  7  and the breathing path  8  are thin relative to a thickness of the case, the filter portion can be configured to be thin. Therefore, as shown in  FIG. 11 , a clearance with the circuit board  4  can be made large to enable the electronic part  4   a  to be mounted below the filter portion. 
       Embodiment 7 
       [0029]      FIG. 7  shows Seventh Example of the present invention. As compared with the above Example  6 , a first breathing path  8   a  is opened from a resin cover upper surface  14   a  toward a metal base  15 , a second breathing path  8   b  is opened in a resin cover-side surface  14   b  so as to be perpendicular to the first path, and both paths cross with each other within a resin cover  14 . A breathing hole  11  is formed at a position at which the first and second breathing paths cross with each other and which is on the inner side of the resin cover  14 , and further inside, a breathing filter film  7  is provided. In this case, the filter film  7  is set based on a positional relationship between the first and second breathing paths  8   a  and  8   b  and the breathing hole  11  so as not to be seen from the outside in order to prevent high pressure water from splashing the filter film  7 . Similarly to Example 6, since the filter portion has a small thickness, parts can be mounted below the filter portion and on the board as well. 
       Embodiment 8 
       [0030]      FIG. 8  shows Eighth Example of the present invention. As compared with the above Example 6, in order to improve drainability, at a resin cover upper surface corner portion  14   c,  breathing paths  8  are provided in a resin cover upper surface  14   a  and a resin cover side surface  14   b  and cross with each other within a resin cover  14 . The breathing path  8  and a breathing hole  11  cross with each other and a breathing filter film  7  is provided below the breathing hole  11 . In this case, the filter film  7  is set based on a positional relationship with the breathing path  8  so as not to be seen from the outside in order-to prevent high pressure water from splashing the filter film  7 . Similarly to Example 6, since a filter portion has a small thickness, parts can be mounted below the filter portion and on the board as well. 
       Embodiment 9 
       [0031]      FIG. 9  shows Ninth Example of the present invention. As compared with the above Example 8, in order to improve drainability, at a resin cover upper surface corner portion  14   c,  a first breathing path  8   a  is formed from a resin cover upper surface  14   a  toward a metal base  15  and a second breathing path  8   b  is formed from the outer side of a resin cover side surface  14   b  toward an inner side of a resin cover  14  so as to cross with each other within the resin base  14 . The breathing paths  8   a  and  8   b  further cross with a breathing hole  11 . A breathing filter film  7  is provided on an inner side of the breathing hole  11  within the resin cover  14 . In this case, the filter film  7  is set based on a positional relationship with the breathing path  8  so as not to be seen from the outside in order to prevent high pressure water from splashing the filter film  7 . Similarly to Example 6, a filter portion has a small thickness to enable parts to be mounted below the filter portion and on the board as well. 
         [0032]    As described in the foregoing, according the present Examples, since water is unlikely to stay in an electronic control equipment irrespectively of a direction, flexibility of layout for mounting the equipment on a vehicle can be increased. Additionally, since arrangement of the filter portion at the case corner portion ensures a clearance between the filter portion and the board, a board fixing structure such as a screw, and an electronic part can be arranged to enable an effect of preventing an increase in a board size to be obtained. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  connector for external connection 
           2  metal cover 
           3  resin base 
           3   a  heat caulking portion 
           4  circuit board 
           4   a  electronic part 
           4   b  heat conductive material 
           5  adhesive 
           6  circuit board fixing screw 
           7  breathing filter film 
           8  breathing path 
           8   a  first breathing path 
           8   b  second breathing path 
           9  breathing path opening surface 
           10  rib 
           11  breathing hole 
           12  angle 
           13  slanting portion 
           14  resin cover 
           14   a  resin cover upper surface 
           14   b  resin cover side surface 
           14   c  resin cover upper surface corner portion 
           15  metal base