Patent Publication Number: US-9853371-B2

Title: Brazed ground terminal for non-ferrous vehicle components

Description:
TECHNICAL FIELD 
     This disclosure relates to the concept of brazing ground terminals for aluminum and other non-ferrous parts of a vehicle. 
     BACKGROUND 
     Vehicle bodies may be manufactured with non-ferrous metals such as aluminum or magnesium. Many electrical vehicle components are connected to ground through the vehicle body. Attaching ground connectors to steel vehicle bodies is accomplished by simply welding the connectors to the steel bodies by resistance welding. 
     Ground wires for aluminum vehicle bodies are connected to expensive weld studs or weld nuts that are welded by resistance welding to the vehicle body. Welding weld studs or weld nuts to aluminum alloys may result in burn through at the location of the welds due to the difficulty in welding to aluminum. Welds of aluminum studs or nuts to aluminum parts results in welds that have reduced tensile and shear strength. 
     Aluminum used for vehicle body parts is heat treatable aluminum alloys commonly referred to a 6XXX aluminum that may be hardened by heating after forming to improve the strength of the material. Welding studs or nuts to heat treated surfaces may create a heat affected zone of the part that results in a loss of the tempering effect and localized reduction of the strength of the part. 
     The above problems and other problems are addressed by this disclosure as summarized below. 
     SUMMARY 
     According to one aspect of this disclosure, a method of manufacturing a grounding connection is disclosed that comprises assembling a non-ferrous grounding connector to a non-ferrous part, and melting brazing material between the grounding connector and the part to secure the grounding connector to the part. 
     According to other aspects of this disclosure as it relates to the above method, the step of assembling the connector to the part may be performed by clinching the connector to the part. The non-ferrous part may be a heat treated aluminum alloy, and the brazing material may have a melting point of between 700° and 900° F. 
     The grounding connector may include features that facilitate depositing the brazing material. In one embodiment, a plurality of feet may be formed of the brazing material that are melted during the melting step. In another embodiment, the grounding connector may have a plurality of sides that define a plurality of channels. The brazing material is melted to flow through the channels that extend from an outer surface of the grounding connector to a surface of the grounding connector that is attached to the part. In another embodiment, a braze washer may be inserted between the ground connector and the part to provide the brazing material that melts in the melting step. 
     The method of manufacturing the grounding connection may be automated and the melting step may be performed by feeding a wire electrode toward an area between the grounding connector and the part and supplying electrical current to melt the wire electrode. Alternatively, the step of melting the braze material may be performed by heating the braze material in a resistance welding operation. 
     In service operations, the melting step may be performed by heating the braze material with a torch. 
     This disclosure also relates to providing a ground connector for a vehicle body that comprises a nut secured to the vehicle body by a clinch joint and a deposit of braze metal applied to the nut at the location of the clinch joint. The nut and vehicle body may define an interstitial gap that is filled by the braze metal. 
     In another embodiment, a ground connector is provided for a vehicle body that comprises a nut defining an opening for receiving a fastener and a deposit of brazing material attaching the nut to the vehicle body. 
     According to other aspects of this disclosure as it relates to the ground connector, the opening may be a non-threaded opening and the fastener may be a self-tapping screw. The brazing material is an aluminum alloy having a melting point of between 700° and 900° F. The nut is an aluminum nut and the vehicle body may be an aluminum body formed of 6XXX series aluminum that was previously heat treated before the filing the interstitial gap with braze metal. 
     The above aspects of this disclosure and other aspects are described below with reference to the attached drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a grounding connector clinched to a vehicle body and secured by a braze deposit that is shown with a wire having connection terminal and a screw. 
         FIG. 2  is a perspective view of a grounding connector nut having braze material feet that are adapted to be melted to secure the nut to the vehicle body. 
         FIG. 3  is a perspective view of a grounding connector nut having channels formed in the nut into which braze material is melted to flow between the nut and the vehicle body. 
         FIG. 4  is an exploded perspective view of a grounding connector nut and a braze washer assembled to the vehicle body before melting the braze washer to secure the nut to the vehicle body. 
     
    
    
     DETAILED DESCRIPTION 
     The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts. 
     Referring to  FIG. 1 , a ground connector  10  is shown attached to a vehicle body  12 . The ground connector  10  includes a nut  16  that is connected by a clinch joint  18  to the vehicle body  12 . A deposit of braze material  20  is melted to flow between the nut  16  and the vehicle body  12 . The braze material  20  permanently connects the nut  16  to the vehicle body  12 . The nut  16  includes a fastener receiving opening  22  that may be a non-threaded opening if a self-tapping screw  24  is used to connect a wire  28  having a terminal connector  30  to the nut  16 . Alternatively, a threaded opening may be used with a conventional screw. Use of the self-tapping screw  24  and braze material  20  provide a good electrical connection between the wire  28  and the vehicle body  12 . 
     The clinch joint  18  is formed by a clinching process. Clinching features (not shown) may be provided on the nut  16  to facilitate the clinching process. 
     Referring to  FIG. 2 , an alternative embodiment of a nut  36  that may be used as a ground connector is shown. The nut  36  includes a plurality of braze material feet  38  at the corners  40  of the nut  36 . The nut  36  includes an opening  22  and is shown attached to the vehicle body  12 . the nut  36  may be attached to the vehicle body  12  in an automated process in which a resistance welder  42  engages the nut  36  causing current to flow through the braze material feet  38  and melt into the interstitial space between the nut  36  and the vehicle body  12 . 
     Referring to  FIG. 3 , another alternative embodiment of a nut  44  that may be used to form a ground connector to allow grounding to the vehicle body  12 . The nut  44  includes a plurality of channels  46  that are provided to facilitate the flow of braze material  20  between an attachment surface  48  and the vehicle body  12 . The channels  46  extend to the attachment surface  48  from an outer surface  50  of the nut  44 . Braze material is supplied to the channels  48  by a wire feed welder  52  to the channel that melts and then flows through the channels  46  to the interstitial space between the nut  44  and the vehicle body  12 . 
     Referring to  FIG. 4 , another embodiment is shown that may be more suitable for service operations where it is necessary to connect a wire to a ground connector. A nut  54  having a fastener receiving opening  22  is shown exploded away from a washer  56  that is formed of braze material. The washer  56  may be a relatively thin foil section of braze material that is placed between the nut  54  and the vehicle body  12 . A gas torch  58  is shown being directed toward the washer  56  of braze material that is used to melt the washer and thereby connector the nut  54  to the vehicle body  12 . 
     The vehicle body  12  is an aluminum vehicle body made up of 6XXX aluminum that has been formed and then tempered to increase the strength of the body  12 . 
     The braze material is preferably an aluminum/nickel/silicon braze material having a melting point of between 700° and 900° F. The melting point of the braze material must be substantially lower than the heat treating temperature used to treat and strengthen the vehicle body  12 . The vehicle body is generally heat treated for a predetermined period of time at a temperature of approximately 1000° F. After heat treating, the six XXX aluminum alloy is substantially strengthened. By attaching the nut with braze material having a melting point of between 700° and 900° F., the strength of the vehicle body is not adversely affected and the heat effective zone of any vehicle component part to which the nut is attached is limited to reduce the loss of tempering and localized reduction of the strength of the part. The brazing temperature of between 700° and 900° F. does not present any risk that attachment of the nut will result in burn through of the component parts of the vehicle body. 
     It should be understood that the automated manufacturing processes may be automated by using a wire feed welder or a resistance welder. The above embodiment of using a clinch joint connection may be completed by applying brazing material with either a resistance welder or wire feed welder. In general, the process is used to melt the brazing material may be interchanged to work with any of the nuts used to provide the grounding connector. 
     The embodiments described above are specific examples that do not describe all possible forms of the disclosure. The features of the illustrated embodiments may be combined to form further embodiments of the disclosed concepts. The words used in the specification are words of description rather than limitation. The scope of the following claims is broader than the specifically disclosed embodiments and also includes modifications of the illustrated embodiments.