Patent Publication Number: US-2022221006-A1

Title: Vehicle drivetrain assembly and method for making the assembly

Description:
TECHNICAL FIELD 
     This invention relates to a vehicle drivetrain assembly for use in transmitting torque between a vehicle engine and driving wheels, and the invention also relates to a method for making the vehicle drivetrain assembly. 
     BACKGROUND 
     Drivetrain assemblies for vehicles are used to transmit torque between a power plant and driving wheels of a vehicle upon rotation about a central axis during the vehicle driving. 
     SUMMARY 
     A vehicle drivetrain assembly comprises first and second torque transmitting members. The first torque transmitting member is made of aluminum and includes an annular planar plate portion having a round opening through which a central axis of the assembly extends. The first torque transmitting member is a clutch hub or housing and includes an annular wall circumferentially-extending around the planar plate portion and having an axially extending spline portion. The second torque transmitting member is made of steel and includes an annular connection location that faces axially relative to the central axis and extends around the round opening of the planar plate portion of the first torque transmitting member. The second torque transmitting member is a sun gear, a ring gear, a torque transmitting hub, or a shaft. An electromagnetic pulse weld forms and connects the plate portion of the first torque transmitting member around its round opening with the connection location of the second torque transmitting member. The electromagnetic pulse weld is progressively applied along a radial direction relative to the central axis of the assembly. 
     A method for making a vehicle drivetrain assembly comprises positioning an annular planar plate portion of an aluminum torque transmitting member having a round opening with a central axis in a spaced relationship adjacent an annular connection location of a steel torque transmitting member with the annular connection location facing axially relative to the central axis and extending around the opening of the aluminum torque transmitting member. The aluminum torque transmitting member is a clutch hub or housing including an annular wall circumferentially extending around the planar plate portion and having an axially extending spline portion, and the steel torque transmitting member is a sun gear, a ring gear, a torque transmitting hub, or a shaft. The method also comprises progressively applying an electromagnetic pulse weld along a radial direction relative to the central axis of the assembly to form and weld the plate portion of the aluminum torque transmitting member to the connection location of the steel torque transmitting member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view without most of its background for illustrating a vehicle drivetrain assembly having connected aluminum and steel members that are electromagnetically pulse welded to each other. 
         FIG. 1 a    is an enlarged view of a portion of  FIG. 1  illustrating a portion of the vehicle drivetrain assembly where the aluminum member is formed and electromagnetically pulse welded to the steel member. 
         FIG. 1 b    is a partial sectional view taken along the direction of line  1   b - 1   b  of  FIG. 1  to illustrate a thin-walled spline portion of the aluminum member. 
         FIG. 2  is a sectional view of the vehicle drivetrain assembly taken as in  FIG. 1  but before the electromagnetic pulse welding. 
         FIG. 2 a    is an enlarged view of a portion of  FIG. 2  similar to  FIG. 1 a    but before the forming and electromagnetic pulse welding. 
         FIG. 3  is a view of another embodiment of the vehicle drivetrain assembly taken in the same sectional manner as  FIG. 1  but also having another aluminum member that is of a lower grade than the first aluminum member and that is located at the electromagnetic pulse weld for enhancing the weld strength. 
         FIG. 3 a    is an enlarged view of a portion of  FIG. 3  similar to  FIG. 1 a    and illustrating the additional aluminum member that is at the formed electromagnetic pulse weld. 
         FIG. 4  is a view of the alternate embodiment of the vehicle drivetrain assembly shown in  FIG. 3  and is similar to  FIG. 2  before the forming and electromagnetic pulse welding shown in  FIGS. 3 and 3   a.    
         FIG. 4 a    is an enlarged view of a portion of  FIG. 4  showing the vehicle drivetrain assembly components prior to the forming and electromagnetic pulse welding. 
         FIG. 5  is a view that illustrates the manner in which the embodiment of  FIGS. 1 and 2  has its aluminum member electromagnetically pulse welded in a progressive manner along a radial direction with respect to the central axis of the vehicle drivetrain assembly to form the weld. 
         FIG. 6  is a view similar to  FIG. 5  that shows the manner in which the two aluminum members of the embodiment of  FIGS. 3 and 4  are progressively formed by the electromagnetic pulse welding along a radial direction with respect to the central axis of the vehicle drivetrain assembly to form the weld. 
         FIG. 7  is a greatly enlarged view that illustrates the atomic bonding of the aluminum and steel members to each other. 
         FIG. 8  is a flow chart illustrating the manner in which the one embodiment of the vehicle drivetrain assembly shown in  FIGS. 1, 1   a ,  2 ,  2   a  and  5  is processed. 
         FIG. 9  is another flow chart illustrating the manner in which the other vehicle drivetrain assembly shown in  FIGS. 3, 3   a ,  4 ,  4   a  and  6  is processed. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIG. 1 , a vehicle drivetrain assembly generally indicated by  10  is constructed in accordance with the invention by the method of the invention and includes a first torque transmitting member  12  made of aluminum, a second torque transmitting member  14  made of steel and an electromagnetic pulse weld  16  that connects the members to each other as is hereinafter more fully described. Both the construction of the vehicle drivetrain assembly  10  and the method of making the assembly will be described in an integrated manner to facilitate an understanding of different aspects of the invention. 
     With continuing reference to  FIG. 1 , the aluminum member  12  includes a planar plate portion  18  of a round shape having a central round opening  20  through which a rotational central axis A of the assembly extends. The second steel member  14  includes an annular connection location  22  that faces axially relative to the central axis A as best shown in  FIG. 2 b    and that extends around the round opening  20  of the planar plate portion  18  of the aluminum member  12 . The electromagnetic pulse weld  16  as shown in  FIG. 1 b    forms and connects the plate portion  18  of the first aluminum member  12  around its round opening  20  with the connection location  22  of the second steel member  14 . Thus, the second steel member  14  has durability for use as required while the first aluminum member  12  advantageously provides the vehicle drivetrain assembly with a lighter construction than would be the case with making it of steel. 
     As illustrated in  FIGS. 1 and 2 , the first aluminum member  12  is a clutch hub or housing defining the plate portion  18  and also having an axially extending thin-walled spline portion  24  which includes thin-walled splines  26  shown in  FIG. 1   b.    
     As also shown in  FIGS. 1 and 2 , the second steel member  14  is shown as a sun gear having helical teeth  28  and also can be constructed as a ring gear, torque transmitting hub or a shaft. 
     As illustrated in  FIG. 5 , the electromagnetic pulse welding forms the plate portion  18  of the aluminum member  12  progressively in a radial direction with respect to the central axis of the assembly as illustrated by the schematic arrows  30  to form the weld  16  to the steel member  14 . The electromagnetic pulse welding provides the weld  16  as illustrated in the greatly magnified (1000.times.) view of  FIG. 7  at an atomic level so as to secure the aluminum and steel to each other. 
     As illustrated in  FIG. 8 , the flow chart  32  illustrates in step  34  the positioning of the aluminum and steel members adjacent to each other as also shown in  FIG. 2  and in step  36  shows applying the electromagnetic pulse weld that forms the atomic bonding of the aluminum and steel. 
     With reference to  FIGS. 3, 3   a ,  4  and  4   a , another embodiment of the vehicle drivetrain assembly is indicated generally by  10 ′ and has the same construction as the previously described embodiment except as will be discussed. As such, like reference numerals are applied to the like components thereof and much of the previous description is applicable such that no repetition thereof is necessary and thus will not be repeated. However, in embodiment  10 ′, another aluminum member  38  is initially positioned as shown in  FIG. 4 a    between the connection location  22  of the steel member  14  and the plate portion  18  of the aluminum member  12  in preparation for the electromagnetic pulse welding. This aluminum member  38  is of a lower grade aluminum than the first aluminum member  12  and thus enhances the atomic bonding to the steel member  14 . More specifically the aluminum member  38  is of a grade with a four digit member whose first digit is lower than the first digit of the four digit member of the grade of the first aluminum member  12  so as to form easier due to its less strength resulting from less alloying. Further, the aluminum member  38  extends around the opening  20  of the plate portion  18  of aluminum member  12  positioned adjacent the steel member connection location  22  where the electromagnetic pulse welding provides the atomic bonding. Also, the aluminum member  38  has a thickness less than 3 mm., preferably 1.5 mm. which herein means 1.5 mm. with a tolerance of plus or minus 10%, so the relatively thin aluminum has less mass than a thicker aluminum member. Thus, the aluminum member  18  is accelerated faster and has a greater impact for providing the better atomic bonding with the steel as is also provided by its less alloyed lower grade. The thicker first aluminum member  12  also atomically bonds with the lower grade aluminum of the thin aluminum member  38 . 
     As illustrated in  FIG. 6 , the electromagnetic pulse welding forms both the plate portion  18  of the aluminum member  12  and the aluminum member  38  progressively in a radial direction with respect to the central axis of the assembly as illustrated by the schematic arrows  30  to form the weld  16  with the steel member  14 . 
     As illustrated in  FIG. 9 , the flow chart  32 ′ illustrates in step  34 ′ the positioning of the aluminum members  12  and  38  and the and steel member  14  adjacent to each other as also shown in  FIG. 3  and in the step  36  shows the next step of applying the electromagnetic pulse weld that forms the atomic bonding of the aluminum and steel. 
     While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.