Abstract:
A frame and cradle assembly for a vehicle comprising side rails and at least one cross member extending there between that define a ladder-like frame having a forward and rearward portion that correspond to the front and rear of a vehicle. At least one mechanical stop disposed on the cross members properly positions the cross members for attachment to the side rails via a tube through tube joint, resulting in a rigid assembly.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to frame and cradle assemblies for vehicles. The present invention particularly relates to an improved structure for a side rail and cross member structure for use with a vehicular body and frame assembly.  
         BACKGROUND OF THE INVENTION  
         [0002]    All vehicles require some type of structural support assembly which is supported upon a plurality of ground engaging wheels by a resilient suspension system. The most common structural support systems are divided into two general categories, namely, separate body-on-frame and unibody. The separate body-on-frame and unibody assemblies are alternative construction methods applied in the automotive industry.  
           [0003]    In the separate body-on-frame assembly, the structural components of the body portion and the frame portion are separate and independent from one another. The frame portion is resiliently supported upon the vehicle wheels by the suspension system and serves as a platform upon which the body portion and other components of the vehicle can be mounted. Similarly, separate automotive cradles may be used to mount certain components to a unibody frame. One example of such a cradle is an engine cradle which supports the engine when attached to a unibody frame. The structure of the body consists of a number of formed members joined together at nodes made from a variety of aluminum or steel product forms. Separate body and frame assemblies of this general type are often found in trucks, sport utility vehicles, and automotive cradles.  
           [0004]    In a typical vehicle frame, cross members extend transversely relative to two parallel side rails, and are permanently secured to the side rails to form a generally rectangular vehicle frame assembly. The cross members are usually secured to the side rails by welding, bolts or rivets. Once the vehicle frame assembly is completed, the remaining components of the vehicle, including the body, drive train, and suspension, can be mounted thereon in a known manner. The side rails are manufactured to a predetermined length which is appropriate for the particular vehicle. The side rails may be formed as single or multiple members that extend most or all of the length of the vehicle. Typically, the side rails are formed from two or more pieces that are overlapped and then bolted, welded, riveted, or otherwise secured together to form a box-shape, i.e., enclosed or tubular, at selected locations along the side rail. Once the side rails are made to length, the frame is assembled by joining the appropriate number of cross members to the side rail to form a single structure. This assembly process has experienced favorable results and wide acceptance, but there is need for improvement.  
           [0005]    A stiffer frame is desired in order to enhance the ride and vibration characteristics of the vehicle. The most acceptable way to increase stiffness of the structure is to use more “boxed” cross members and side rails. The increase in boxing of these components can make it more difficult to attach the cross members and side rails together quickly and rigidly without using more expensive subassemblies or tooling. The reason is that instead of simply matching two or three sides of a boxed section together for attachment purposes, all sides must contact each other. The more contact between parts, the more precise they must match. Moreover, the more precise the part the more expensive the part. A better fit typically provides the benefit of a better and more durable joint.  
           [0006]    The requirements of boxed sections coming together also can impact the assembly process in another way—“fit up” problems. The boxing of the structures makes them stiffer and less forgiving when the structures are joined. Special care must be exercised to get the required structure fit up. This can result in a slower assembly process, which can add significantly to the cost of the frame, or cradle. Or, the required special care will add to the cost of tooling to form a more precise fit up surface.  
           [0007]    In view of the above, it is apparent that there is a need to provide a more rigid and durable vehicle frame assembly. A more rigid frame improves the steering and handling of the vehicle. There is also a need to provide a vehicle frame that is efficient and simple to assemble. An efficient assembly process reduces the overall procedure time required and therefore reduces labor costs and other overhead.  
           [0008]    The present invention is drawn to solve the problems associated with assembly of the multi-component vehicle frames.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    In view of the foregoing, it is an object of the present invention to provide a vehicle frame or cradle assembly that addresses the limitations and disadvantages associated with prior vehicle frames, yet meets the needs of the users.  
           [0010]    A further object of the invention is to provide a reliable vehicle frame assembly that, requires minimal effort by the user to assemble.  
           [0011]    Still another object of the invention is to provide a vehicle frame assembly that reduces vehicle frame manufacturing times and associated costs.  
           [0012]    In one embodiment of the invention, two elongated longitudinal members or side rails are positioned to form the side rails of the vehicle frame or cradle. At least one tubular cross member is connected to the side rails. A collar or stop member is formed proximate each end of the at least one cross member for attachment to side rails. Each side rail has at least one opening extending transversely through the side walls. The number of openings in the side rails correspond to the number of cross members. Each end of cross member is placed through an opening in a side rail, extending completely through the side rail and beyond the distal side wall of the side rail. The at least one cross member is rigidly attached to the side rails.  
           [0013]    These and other objects not specifically enumerated herein are believed to be addressed by the present invention which contemplates a vehicle frame assembly that includes a left and right longitudinal members or side rails, at least one cross member rigidly attached to the side rails via a tube through tube joint to form a stiff vehicle frame. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.  
         [0015]    [0015]FIG. 1 is a perspective view of a preferred embodiment of the present invention including a plurality of cross members engaging the side rails to form a vehicle frame assembly.  
         [0016]    [0016]FIG. 2 is a cross sectional view of a side rail of the present invention taken at  4 - 4  of FIG. 1.  
         [0017]    [0017]FIG. 3 is a side perspective view of a cross member of the present invention.  
         [0018]    [0018]FIG. 4 is a detailed end view of the present invention.  
         [0019]    [0019]FIG. 5 is a detailed view of FIG. 4 taken at  5 - 5 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    The description contained herein relates to the specific structures of a vehicle frame assembly, as presently contemplated. This description, however, is intended to be illustrative only and not limiting as to the scope of the present invention. For example, while the invention will be described in the context of light truck frame, the invention is applicable to a variety vehicle frame assemblies, such as sport utility vehicles (suv) and automobile cradles, as well.  
         [0021]    In the drawings, where like numerals indicate like elements, there is shown a vehicle frame assembly in accordance with the present invention. The drawings are schematic in that non-essential structures and elements have been omitted.  
         [0022]    As shown in FIG. 1, a vehicle frame assembly or cradle  10  incorporating the features of this invention. The vehicle frame assembly  10  includes side rails  12  connected to one another by cross members  14 , via tube-through-tube joints, forming a ladder-like orientation defining the vehicle frame. The cross members  14  are rigidly attached to the side rails, as will be described in further detail herein below.  
         [0023]    Each side rail  12  is an elongated member having a first or front end  16 , a second or rear end  18 , an inner wall  20 , and an outer wall  22 . The side rails  12  are made of a material of sufficient stiffness to form a rigid vehicle frame, e.g. steel, aluminum, an extruded material, or the like. The side rail  12  may be a unitary member or comprise a plurality of portions rigidly attached to one another. The side rails  12  may have any cross sectional shape necessary to meet the needs of the frame. Further, side rails  12  may be curved along its longitudinal axis as required.  
         [0024]    As shown in FIG. 2, portions of the side rail  12  are formed as an elongated rectangular tube formed of two c-shaped members  24  rigidly attached by welds  26 . This is often incorporated where additional strength or rigidity is required, for example, where cross members  14  are attached. Alternatively, the side rails may be non-tubular such as a “single-wall” member.  
         [0025]    In order to accomplish the efficient attachment of cross member  14  to the side rail  12 , at least one coaxially aligned hole extends through both inner wall  20  and outer wall  22  of side rail  12 . Specifically, aperture  27  is formed in inner wall  20  and is coaxial to aperture  28  formed in outer wall  22 . Aperture  27  has a diameter D 1  that is greater than diameter D 2  of aperture  28 . Aperture  27 , having a larger diameter, increases the margin of error in the process of inserting a cross member  14  as will be explained in greater detail herein below. Alternatively, the diameter of the coaxial apertures may be the same size, or any size desired.  
         [0026]    Cross member  14  is an elongated hollow member having opposed ends  32 . Cross member  14  is made of a material of sufficient stiffness, such as steel, aluminum, or an extruded material, to form a rigid frame member. Cross member  14  is preferably an elongated tube with a circular cross section. However, the elongated cross member  14  may extend in a non-linear fashion to provide clearance for other components, such as the gas tank, engine, or the like.  
         [0027]    As shown in FIG. 3, a collar or stop member  34  is formed on the cross member proximate the ends  32 . The collar  34  extends radially outwardly from the outer surface of cross member  14 , providing a diameter greater than the rest of the cross member  14 . A collar  34  may be located proximate one end of cross member  14  or at both ends. The collar or stop member  34  makes the coaxial alignment of apertures  27  and  28  less critical as the collar  34  is shaped so as to cover or make up for any difference in the alignment of the axial holes or difference in diameter. Further, collar  34  allows for the use of a larger diameter D 1  for inner aperture  27 .  
         [0028]    Collar  34  is formed to be integral with cross member  14  by a standard end forming process that uses a clamping tool to hold the cross member while a hydraulic ram cylinder advances with a form tool to form the collar  34 . However, collar  34  may be formed by other methods such as an extrusion process, bending, or the like.  
         [0029]    Alternatively, a cross member  14  may have a stepped diameter or a conical section (not shown), wherein the outermost portion of each end of cross member  14  has a diameter less than the rest of the cross member  14 . The collar or stop member  34  is formed by the increased diameter portion of cross member  14 .  
         [0030]    Referring to FIG. 1, two side rails  12  are positioned to form a left side longitudinal member and a right side longitudinal member, i.e., the left and right sides of the vehicle frame respectively. A plurality of cross members  14  are inserted into a corresponding number of coaxial holes in the side rails  12 , and rigidly attached thereto, as shown. The side rails  12  and plurality of cross members  14  define a ladder-like frame having a forward portion  36  and a rearward portion  38  that correspond to the front and rear of the vehicle.  
         [0031]    Method of Assembly of Vehicle Frame  
         [0032]    The present invention also contemplates a method of assembling a vehicle frame using tube-through-tube joints. The method includes providing the various components of a vehicle frame  10  as shown in FIGS. 1 through 3. Side rails  12  are provided with the number of axially aligned holes required for the intended vehicle. Cross members  14  are provided in number corresponding to the number of axial holes in the side rails  12 .  
         [0033]    As shown in FIG. 4, one end of cross member  14  is inserted, as indicated by arrow A, into aperture  27  of inner wall  20  and extended completely through the side rails  12 , through aperture  28  and beyond outer wall  22  until collar  34  complimentarily engages inner wall  20 . The opposite end of cross member  14  is inserted into a corresponding aperture  27  in the other side rail  12 , as indicated by arrow B. This procedure is repeated for all the cross members  14 .  
         [0034]    As stated above, aperture  27  has a greater diameter than aperture  28 . Having an inner aperture larger than the outer aperture greatly reduces assembly time and the occurrence of misaligned cross members requiring discarding of the vehicle frame. With the current invention, assembly tools only have to align cross member  14  with aperture  28  in the outer wall of side rail  12  rather than apertures in both the inner wall  20  and outer wall  22  of the side rails. As shown in FIG. 5, the difference in the two aperture diameters makes the coaxial alignment of apertures  27  and  28  less critical, as the collar  34  is shaped so as to cover or make up for any gaps  42  created by aperture  27  being larger than the outer diameter of cross member  14 .  
         [0035]    The plurality of cross members  14  are rigidly attached to side rails  12  by welds  40  at the joint of cross member  14  and outer wall  22 , or the joint of cross member  14  and the circumference of collar  34 , or both locations. Alternatively, a press fitting bushing, friction fit, or the like may be incorporated to connect cross member  14  to side rails  12 .  
         [0036]    Extension of the cross members  14  through side rails  12  provides two rigid attachment points of the cross member  14  to the side rail  12  at the inner and outer walls of side rails  12 , creating a much more rigid joint. More rigid joints create a stiffer vehicle frame, which improves vehicle performance, such as steering, handling, and the like.  
         [0037]    Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.