Patent Publication Number: US-6992248-B1

Title: Junction box assembly with connectivity assurance

Description:
BACKGROUND 
     This invention relates to a junction box assembly that assures good connectivity between connectable components that are inside and/or part of the junction box assembly. 
     In the assembly and use of electrical components, it is important that good electrical contact is established between connected electrical components, and that the electrical contact is not accidentally broken during use. Some connectors have locking tabs that snap into engagement to physically lock the connectors to mating connectors when the electrical contact is fully established. 
     SUMMARY 
     Locking structures have also been provided on electrical junction boxes and/or components accommodated inside the junction boxes. However, even in junction boxes with such locking structures, there is a chance that electrical contact can be insufficiently established and/or can be broken during use, if, for example, the assembly operator fails to fully connect the junction box parts and/or interior components. This is increasingly a problem as more and more connections are made in junction boxes due, for example, to the demand for more and more electrical features in automobiles. Specifically, for example, as more terminals are contained within a given connector, the force required to push the connector into engagement with a mating connector increases. This increase in required assembly force makes it more likely that the connection will be insufficiently established. Operator fatigue in an assembly line, or simply human error, can be other factors leading to insufficient connection. There is also a possibility that the locking structures can be accidentally disengaged during certain operating conditions of a vehicle in which the junction box is installed. 
     Insufficient connection and accidental disconnection can lead to warranty and safety problems. 
     Therefore, an object of this invention is to ensure sufficient connection between components, and/or to provide a visual, audible and/or tactile indication when a connection is not sufficient. 
     Embodiments of the invention provide a junction box assembly including a lower cover, a junction box and an upper cover. The junction box holds one or more connectors that mate with corresponding connectors in the lower cover. The junction box includes a locking structure that engages with a corresponding locking structure of the upper cover. The junction box also includes a cover engagement restriction portion. The upper cover includes a lock position assurance device that abuts against the cover engagement restriction portion and restricts the upper cover from engaging the lower cover if the junction box is not properly installed into the lower cover. 
     One or more disconnection restriction portions may be provided on the upper cover, contacting or being closely adjacent to the junction box in a state in which the lower cover, the junction box and the upper cover are fully assembled. The disconnection restriction portions can help restrict accidental disengagement of the junction box from the lower cover. 
     These and other objects, advantages and salient features of the invention are described in or apparent from the following detailed description of exemplary embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention will be described with reference to the drawings, wherein like numerals represent like parts, and wherein: 
         FIG. 1  is an exploded view of a lower cover, a junction box and an upper cover that connect together to form a junction box assembly; 
         FIG. 2  illustrates a state in which the upper cover is brought into contact with the junction box; 
         FIG. 3  illustrates a state in which the junction box is incompletely inserted into the lower cover, and the upper cover is restricted from being engaged with the lower cover; 
         FIG. 4  illustrates a state in which the lower cover, the junction box and the upper cover are fully assembled; and 
         FIG. 5  illustrates a vehicle in which is mounted the junction box assembly of  FIGS. 1–4 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of this invention can provide the following advantages, separately or in any combination:
         (1) Assurance that connection between connectors of a junction box and connectors of a lower cover is complete;   (2) Assurance that the junction box is properly installed in the lower cover; and   (3) Restriction of accidental release of the junction box from the lower cover.       

       FIG. 1  is an exploded view of a lower cover  10 , a junction box  20  and an upper cover  30  that connect together to form a junction box assembly  100 . The lower cover  10  accommodates connectors  12 , which may, for example, be staged connectors such as are disclosed in related copending U.S. application Publication No. U.S. 2003/0211764 A1, the disclosure of which is incorporated herein by reference in its entirety. The lower cover  10  also has locking arms  14  extending toward an open end of the lower cover  10 . The locking arms  14  have locking projections  16  that project inward towards each other. The lower cover  10  also includes a cover locking structure  18 . 
     The locking arms  14  are depicted as having free ends, but the ends may in fact be attached to a sidewall of the lower cover  10  so that the ends do not deflect inward or outward. (The sidewall is removed in the figures for better clarity of the interior components of the lower cover.) Although it is possible to allow the locking arms  14  to have free ends, it is generally preferably to attach the ends to the sidewall, by integral molding, for example, to improve the reliability of the engagement between the lower cover  10  and the junction box  20 . 
     The junction box  20  includes connectors  22  that mate with the connectors  12 . At an upper surface of the junction box  20 , relays, fuses and/or other electrical devices (not shown) may be installed as appropriate to make various desired connections between terminals of the connectors  22 . The junction box  20  also includes a locking structure  24  that engages the locking arms  14  of the lower cover  10 . In this embodiment, the locking structure  24  includes locking arms  242  that are connected to the junction box  20  via connection ribs  248 . Locking projections  244  project outward from the locking arms  242 , and free end portions of the locking arms  242  form cover engagement restriction portions  246 . 
     The upper cover  30  covers and engages the lower cover  10  and the junction box  20 . The upper cover  30  may include disconnection restriction portions  32  and  34  that contact or are closely adjacent to the junction box  20  in a state in which the lower cover  10 , the junction box  20  and the upper cover  30  are fully assembled. The disconnection restriction portions  32  and  34  may be of any desired or convenient configuration, but in this embodiment, the disconnection restriction portion  32  is in the form of a lip that extends in a direction perpendicular to the plane of the page, and extends substantially along the entire length of a sidewall of the upper cover  30 . The disconnection restriction portion  34  is in the form of a rib that is integral with the upper cover  30 . 
     The upper cover  30  also may include a locking arm  36  with a locking projection  362  that engages the cover locking structure  18  of the lower cover  10  when the upper cover  30  is brought into engagement with the lower cover  10 . A lock position assurance device  38 , hereafter called a tab  38 , extends from a wall of the upper cover  30 . 
     Only one locking structure  24 , one pair of locking arms  14 , and one tab  38  are depicted, but any desired number may be provided. It is generally preferable to have two locking structures  24 , provided on opposite sides of the junction box  10 , with corresponding tabs  38  provided in the upper cover  30  and corresponding pairs of locking arms  14  provided in the lower cover  10 . 
       FIG. 2  illustrates a state in which the upper cover  30  is brought into contact with the junction box  20 . Because the junction box  20  has not yet been installed in the lower cover  10 , the upper cover  30  does not engage the lower cover  10 . 
       FIG. 3  illustrates a state in which the junction box  20  is incompletely inserted into the lower cover  10 , and the connectors  22  are only partially mated with the connectors  12 . In this state, the locking arms  242  of the junction box  20  are deflected inward towards each other to a point of maximum deflection. The tab  38  has a width that is greater than a distance between the free ends of the locking arms  242 , that is, the cover engagement restriction portions  246 , at the point of maximum deflection of the locking arms  242 . Therefore, in this state, the tab  38  abuts against the cover engagement restriction portions  242  and restricts the upper cover  30  from fully engaging the lower cover  10 . Therefore, the locking element  362  of the upper cover  30  cannot engage the locking structure  18  of the lower cover  10 . Advantageously, this state results in feedback to the assembly operator, alerting the operator that the junction box  20  has not been properly installed. The feedback may be visual, tactile or audible, or any combination of these. 
     The visual feedback may simply be in the form of a visual observation that the upper cover  30  is not fitting properly on the lower cover  10 . The tactile feedback may be a tactile sensation that the upper cover  30  is not fitting properly on the lower cover  10 , and/or a tactile perception of the absence of a “click” feeling that should happen when everything is properly engaged and the locking arms snap into place. The audible feedback may be a perception of the absence of a “click” sound that should happen when everything is properly engaged and the locking arms snap into place. 
       FIG. 4  illustrates a state in which the lower cover  10 , the junction box  20  and the upper cover  30  are fully assembled, and the connectors  22  are completely mated with the connectors  12 . Because the junction box  20  is properly installed in the lower cover  10 , the locking arms  242  deflect outward against the locking arms  14 , so that the locking projections  244  engage the locking projections  16 . The tab  38  can therefore fit between the cover engagement restriction portions  246 , and the locking element  362  of the upper cover  30  can engage the locking structure  18  of the lower cover  10 . The disconnection restriction portions  32  and  34  contact or are closely adjacent to the junction box  20 , helping to restrict the junction box  20  from disengaging the lower cover  10 . 
     The width of the tab  38  is great enough to restrict the cover engagement restriction portions  246  from deflecting inward to a degree that the locking projections  244  could disengage the locking projections  16 . Therefore, the junction box  20  cannot be disengaged from the lower cover  10  until the upper cover  30  is removed, and accidental disengagement of the junction box  20  is thereby avoided. Additionally, a distal end of the tab  38  is preferably tapered, as shown in the drawings, to help guide the tab  38  into its proper position and thereby make assembly easier. The tapered end of the tab  38  can also, by pushing against the cover engagement restriction portions  246 , help push the locking projections  244  into engagement with the locking projections  16 . This feature is particularly useful if, for example, there is a slight amount of friction between the locking projections  244  and the locking projections  16  that prevents the locking arms  242  from deflecting outward to the fully locked position on their own. 
       FIG. 5  illustrates a vehicle in which is mounted the junction box assembly  100 . 
     While the invention has been described in conjunction with specific embodiments, these embodiments should be viewed as illustrative and not limiting. Various changes, substitutes, improvements or the like are possible within the spirit and scope of the invention.