Abstract:
An electrical connection box has a substrate carrying electrical components, a molded synthetic resin casing fitted on the substrate at the lower side thereof, and a connector receivable in the casing and mountable at a predetermined position on the substrate. The connector has electrical terminals engageable with electrical terminals of the substrate. A fastener is inserted in the substrate to draw the connector to its predetermined position. A holder for the connector is molded in one piece with the casing, and is open at its upper side to receive the connector. The connector and the holder have holding elements which are mutually engageable to hold the connector in the holder, prior to the operation of the fastener to draw the connector to its predetermined position, whereby the fastener through the connector holds the casing at its fitted position on the substrate.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an electrical connection box suitable to be mounted on a vehicle, such as an automobile.  
           [0003]    2. Description of the Related Art  
           [0004]    [0004]FIG. 6 shows one known form of an electrical connection box of a vehicle. Electrical parts  32 , such as relays, are mounted on an upper surface of a substrate in a junction block  31 . A lower casing or cover  33  for the junction block  31  is fitted on the junction block  31  from below. The lower cover  33  accommodates connectors  34  connected to the end of a wire harness not shown in FIG. 6. The wire harness passes out of the lower cover  33  through an aperture (not shown) in the lower cover. Columnar projections  35  for temporarily locking the connectors  34  to the lower cover  33  project up from the base of the lower cover  33 . Approximately cross-shaped temporary locking holes  36  into which the projections  35  can be inserted are formed in the base of lower covers  37  that are fitted on a lower side of the connectors  34 .  
           [0005]    When assembling the electrical connection box of FIG. 6, initially the lower covers  37  are fitted on the connectors  34 . Then the projections  35  are inserted into the temporary locking holes  36  of the covers  37  to temporarily lock the connectors  34  to the base of the lower cover  33 . Then, with the lower cover  33  fitted on the junction block  31 , bolts  38  inserted through the junction block  31  into complementary screwthreads of the connectors  34  are tightened. As a result, the connectors  34  are brought up to the junction block  31  and fixed in position on the junction block  31 , so that terminals of the components  32  engage terminals in the connectors  34 .  
           [0006]    However, in this construction, the gap between the connectors  34  and the lower covers  37  is large. Therefore, vibration causes both the connectors  34  and the lower cover  37  to be loosened and to shake. Consequently, noise is apt to be generated.  
           [0007]    Further, because the lower cover  37  is required in assembling the electrical connection box, a large number of component parts are required. Thus, the manufacturing cost of the electrical connection box is high.  
           [0008]    GB-A-2338355 shows an electrical connection box similar to that of FIG. 6, in which a flotation bracket, which is lockable into position on the lower cover, is provided inside the lower cover. The bracket receives the connectors from below, for initial positioning of the connectors.  
         SUMMARY OF THE INVENTION  
         [0009]    Accordingly, it is an object of the present invention to provide an electrical connection box that has a construction which does not generate noise easily and can be made at low cost.  
           [0010]    According to the present invention, there is provided an electrical connection box that includes:  
           [0011]    (i) a substrate that carries electrical components and has a plurality of electrical terminals,  
           [0012]    (ii) a molded synthetic resin casing adapted to be fitted on the substrate at the lower side thereof,  
           [0013]    (iii) at least one connector that is receivable in the casing and mountable at a predetermined position on the substrate and has a plurality of electrical terminals engageable with said electrical terminals of the substrate when the connector is brought to its predetermined position,  
           [0014]    (iv) at least one fastener inserted in the substrate and engageable with the at least one connector and operable to draw the at least one connector to the predetermined position, and  
           [0015]    (v) at least one holder for the connector that is molded in one piece with the casing and is open at its upper side to receive the connector.  
           [0016]    In the electrical connection box, the connector(s) and the holder(s) have respective holding elements which are mutually engageable to hold the connector(s) in the holder(s), prior to the operation of the fastener to draw the connector to its predetermined position, whereby the fastener(s) through the connector(s) holds the casing at its fitted position on the substrate.  
           [0017]    Preferably, the holder is constituted by at least two upstanding walls in the casing and the holding elements include mutually abutting projections on mutually opposed surfaces of the connector and the upstanding walls.  
           [0018]    Preferably, the holding element of each upstanding wall has a cantilever arm projecting downwardly and integrally connected at its upper end with the side wall. This projection is preferably at the lower free end of the cantilever arm.  
           [0019]    In the present invention, the connector is first engaged by the holder by insertion from above. The holder is integral with the casing, so that loosening of the connector from the casing is prevented. No additional part, such as the lower cover  37  of FIG. 6, is required in temporarily fixing the connector to the casing. Thus, the electrical connection box requires a smaller number of component parts than the known electrical connection box, and the manufacturing cost is reduced. The operation of the fastener, e.g. a bolt, draws both the connector and the casing into position, and holds them in the final position, so that loosening of the parts is minimized. Thus, noise is not generated in use.  
           [0020]    In the present invention, each holder is preferably integral with the casing. In particular, the holding element of each holder is integral, so that the provision of the holder(s) does not increase the number of component parts. Thus the electrical connection box can be produced at a low cost.  
           [0021]    It is easy to assemble the electrical connection box.  
           [0022]    In this specification and claims, the directional terms “upper”, “lower” etc. are used for convenience and clarity of description, and are not intended to limit the invention. The electrical connection box of the invention may be assembled and used in any appropriate orientation. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    Embodiments of the invention will now be described by way of non-limitative example, with reference to the drawings, in which:  
         [0024]    [0024]FIG. 1 is an exploded perspective view showing an electrical connection box which is an embodiment of the present invention;  
         [0025]    FIGS.  2  to  4  are sectional views showing stages of the procedure for assembling the electrical connection box of FIG. 1;  
         [0026]    [0026]FIG. 5 is an exploded perspective view showing an electrical connection box which is another embodiment of the present invention; and  
         [0027]    [0027]FIG. 6 is an exploded perspective view of a known electrical connection box described above. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    An electrical connection box  1 , suitable for a vehicle, shown in FIGS.  1  to  4 , is typically installed in an engine room of a vehicle to distribute power to component electrical parts in the vehicle. A junction block  2 , made of synthetic resin, accommodates a bus bar laminate not shown in FIGS.  1  to  4 . A plurality of electrical parts  3  such as fuses, relays and the like are mounted on an upper surface of the junction block  2 . Two spaced apart guide portions  4 , cylindrical in this example, project upward from the upper surface of the junction block  2 . As shown in FIGS.  2 - 4 , a bolt insertion hole  5  penetrating through the junction block  2  is formed at the center of each guide portion  4 . A bolt  6  constituting a fastener can be inserted into each bolt insertion hole  5  from above the junction block  2 . Two walls  7 , rectangular in this example, project downward from the lower surface of the junction block  2  around the respective bolt insertion holes  5 . A plurality of male terminal tabs (not shown) of bus bars of the bus bar laminate project down in the regions surrounded by the walls  7 .  
         [0029]    As shown in FIGS.  1  to  4 , an upwardly open casing in the form of a lower cover  11  is fitted on the junction block  2  from below. The lower cover  11  may be molded of suitable synthetic resin and may, for example, be of rectangular box shape. When fitting the lower cover  11  on the junction block  2 , the junction block  2  is seated on a stepped portion  12  formed on the inner surface near the opening of the lower cover  11 . As a result, the junction block  2  is supported horizontally by the lower cover  11 , parallel with the base  13  of the lower cover  11 .  
         [0030]    A plurality of molded connectors  15  (two in this embodiment) is accommodated in the space  14  between the lower surface of the junction block  2  and the base  13  of the lower cover  11 . Each connector  15  is made of synthetic resin and is of rectangular shape. A plurality of female contacts or terminals  16  is embedded inside the connectors  15  such that the female contacts  16  extend vertically. The male terminal tabs of the bus bars of the junction block  2  can be removably inserted into the open ends of the female contacts  16  at the upper surface of the connector  15 . A through-hole  17  extending vertically may be formed at the center of the upper surface of the connector  15 . A threaded nut  18  is embedded inside the through-hole  17 , and a bolt  6  is screwed into the nut  18 . The wire harness (not shown) extends from the lower surface of the connectors  15 , with each electrical wire of the wire harness connected to one of the female contacts  16 .  
         [0031]    The electrical connection box  1  may have an arrangement for fixing the connectors  15  temporarily to the lower cover  11 , before the connectors  15  are fixed to the junction block  2 .  
         [0032]    As shown in FIGS.  1  to  4 , each connector  15  has locking projections  21  serving as first holding elements. The locking projections  21  may be formed at a plurality of positions on the side surfaces  15   a  of the connector  15 . For example, the locking projections  21  may be formed on each of the four side surfaces  15   a  (in total, four locking projections  21  are formed). Each locking projection  21  is located at the central lowermost position of the side surface  15   a . In the embodiment, each locking projection  21  has a shape of an inverted triangle in vertical section and is molded integrally (in one piece) with the connector  15 .  
         [0033]    The lower cover  11  has a pair of open-topped boxes  22  serving as holders for the connectors, molded integrally with the outer walls and base of the cover  11 . Each box  22  is formed by four walls  22   a  standing up from the inner surface of the base  13  of the lower cover  11  and is rectangular. The external dimension of the box  22  is a littler larger than that of the connector  15 . The height (depth) of the box  22  is also a little larger than that of the connector  15 . Thus, when the connector  15  is inserted into the box  22 , the box  22  surrounds the entire periphery of the connector  15 .  
         [0034]    Each box  22  has four flexible locking pieces  23  serving as second holding elements, formed at a plurality of positions around the box  22  on the respective walls  22   a , corresponding in position to the four locking projections  21  of the connector  15 . In each connector-holding box  22 , a vertical slot  24  is formed at the center of each of the four walls  22   a  constituting the box  22 . A base portion (upper end) of the locking piece  23  is connected with the upper edge of the slot  24 . The locking piece  23  extends toward the lower end of the box  22 . A claw  25  is formed on the inner side of the front portion (lower end) of the locking piece  23 . As shown in FIG. 2, the distance between the lower end of the box  22  and the lower end of the claw  25  is about half of the height of the box  22 . In the embodiment, the locking piece  23  is molded integrally (in one piece) with the box  22 .  
         [0035]    In assembling the electrical connection box  1  having the above-described construction, the wire harnesses connected with the connectors  15  are drawn out through holes  26  formed in the base  13  of the lower cover  11 . As shown in FIG. 2, each connector  15  is pressed into the box  22  from above (downward from the top opening of the lower cover  11 ). Then, as shown in FIG. 3, the connector  15  is inserted into the respective box  22  to temporarily seat the connector  15  on the base  13  of the lower cover  11 . As the connector  15  is pressed into the box  22 , the locking pieces  23  deform outwardly and elastically, by contact with the projections  21 . After the projections  21  have passed beneath them, the locking pieces  23  return to their original configurations.  
         [0036]    [0036]FIG. 3 shows the connectors  15  inserted deeply into the boxes  22 . At this time, because the locking projections  21  and the locking pieces  23  are spaced, they are not engaged to each other. If a force is applied upwardly to the connector  15 , the connector  15  moves upward a little. As a result, the locking projections  21  engage the claws  25  of the locking pieces  23 . In this way the connector  15  is prevented from moving further upward and is held reliably inside the box  22 . That is, the connector  15  is prevented from being removed from the connector-holding box  22 .  
         [0037]    Then, the lower cover  11  is fitted on the junction block  2  from below to support the junction block  2  at the stepped portion  12  of the cover  11 . The bolts  6  inserted through the holes  5  of the junction block  2  are engaged in the nuts  18  and tightened. As a result, as shown in FIG. 4, the connectors  15  are drawn upwardly towards the junction block  2 , bringing the connectors  15  into the rectangular walls  7 , with the two connectors  15  in alignment with each other and fixed tightly to the junction block  2 . At this time, the male tabs of the junction block  2  are connected to the female contacts  16 .  
         [0038]    Thereafter, an upper cover (not shown) may be mounted on the lower cover  11  to cover the junction block  2  from above.  
         [0039]    This embodiment provides the following effects:  
         [0040]    (1) The electrical connection box  1  of the embodiment has integral structure that holds the connectors  15  in the cover  11 , including the locking projections  21  and the boxes  22  with the locking pieces  23 . Thus, no lower cover fitted on the connector  15  is required when temporarily fixing the connector  15  to the lower cover  11 . Accordingly, the electrical connection box of the embodiment has a smaller number of component parts than the known box of FIG. 6, and manufacturing cost is reduced. Because no lower cover on the connector  15  is required, there is no problem of looseness of such a lower cover and no risk of noise generation.  
         [0041]    (2) In the electrical connection box  1 , the entire periphery of the connector  15  is surrounded by the holding box  22 . In addition, the locking projections  21  engage the flexible locking pieces  23 , preventing movement of the connector  15  out of the box  22 . Therefore, the connector  15  is reliably retained in position in the lower cover  11 .  
         [0042]    (3) The box  22  and the locking piece  23  are integral with the cover  11 . Thus, the formation of a plurality of the locking pieces  23  does not increase the number of component parts. The electrical connection box  1  can be produced at a low cost. Because the claw  25  is formed on the inner side of the lower end of the locking piece  23 , the locking projection  21  can be reliably locked to the lower end of the locking piece  23 . The locking pieces  23  on the box  22  extend downward, so that it is possible to mount the connector  15  in the box  22  smoothly so that assembly of the electrical connection box  1  is easy.  
         [0043]    (4) As FIG. 4 indicates, the action of drawing the connectors  15  upwardly into their final positions on the junction block  2  also secures the lower cover  11  in position on the block  2 , since the locking elements  21 ,  23  are brought into engagement. The one-piece construction of the lower cover  11  can be easily molded with sufficient precision to achieve this effect, and the flexibility of the claws  25  gives some tolerance while avoiding the possibility that the cover  11  becomes loose on the block  2 .  
         [0044]    The following modifications of the embodiment within the scope of the invention may be mentioned:  
         [0045]    The holder  22  is not necessarily box-shaped, i.e. it need not be continuous such that it surrounds the connector  15  completely in a horizontal direction. For example, the box  22  may be divided into sections at its corners or at other positions. In the electrical connection box  1  of another embodiment of the invention shown in FIG. 5, instead of the continuous box  22 , an opposed pair of upstanding cross walls  27  formed integrally with the lower cover  11  constitute a holder to receive each connector  15 . The walls  27  carry locking pieces  23 . The number of such walls  27  is not limited to two, but may be altered as desired. The configuration and number of the locking projections  21  can be altered as desired. The first locking elements on the connector  15  are not necessarily convex (projection) but may be concave, such as, groove shaped. The configuration and number of the holding boxes  22  can be altered as desired. The configuration and number of the locking piece  23  can be also altered as desired.  
         [0046]    Instead of the holding box  22  projecting from the base  13  of the lower cover  11 , it may project from the inner surface of the side walls of the cover  11 .  
         [0047]    Instead of embedding the nut  18  in the connector  15 , the connector  15  may be fixed to the junction block  2  in another manner by the bolt  6 , or a fastener other than the bolt  6  may be used.  
         [0048]    An electrical part-mounting block (for example, relay block, fuse block and the like) other than the junction block  2  may be used to construct the electrical connection box  1 .