Patent Publication Number: US-2009236877-A1

Title: Vehicle Frame Assembly And Method Having Flexible Modular Architecture

Description:
TECHNICAL FIELD 
     This disclosure relates to body-on-frame automobile construction. Specifically, a unique flexible architecture for, and method of, assembling frames for a wide variety of body-on-frame vehicles from shared modules. 
     BACKGROUND OF THE INVENTION 
     Body-on-frame is an automotive industry manufacturing methodology whereby a separate body is mounted to a rigid frame which supports the body, drivetrain, and suspension. As opposed to body-integrated-frame or monocoque construction, body-on-frame remains the preferred construction method for heavier-duty vehicles, especially those which are intended to carry and pull loads, such as trucks and pickup trucks, and those which are off-road capable, such as sport-utility vehicles. 
     Body-on-frame automobiles have previously required distinct frames for each vehicle size, wheelbase variation, and body style. This, in turn, requires that distinct engineering and manufacturing design solutions be created for each vehicle size, wheelbase variation, and body style. For example, an automotive manufacturer may have a small sport-utility vehicle with a wheelbase of 2870 millimeters (113 inches), a mid-size sport-utility vehicle with a wheelbase of 2945 millimeters (116 inches), and small pickup truck with a wheelbase of 2820 millimeters (111 inches); and each of these, otherwise similarly-sized, vehicles would require a distinct frame created from distinct frame components. Creating distinct frame components incurs substantial design and production costs for proofing, tooling, and testing of manufacturing processes used to produce the final frame. 
     SUMMARY OF THE INVENTION 
     A unique assembly and method having flexible modular architecture for body-on-frame vehicle construction is provided by replacing distinct frame components with commonly-shared, substantially-identical frame modules. Previously unknown flexibility in body-on-frame construction is provided, allowing commonality of frame modules used in assembly of frames for multiple vehicle platforms. With this new modular body-on-frame architecture, substantially-identical frame modules are used to create frames with different sizes, wheelbases and configurations. Furthermore, this truly modular body-on-frame architecture also allows extensive part-sharing schemes across multiple vehicle model lines and platforms. Using the method of assembling vehicle frames from this unique modular body-on-frame architecture, a vehicle manufacturer may improve the time and cost efficiency of manufacturing and assembling frames for diverse vehicle platforms. 
     A method of assembling vehicle frames from a flexible modular architecture is provided. The method comprises first providing substantially identical front and substantially identical rear modules, and providing middle modules with constant-section longitudinal rails that are formable to a variety of desired lengths. The components are assembled by first trimming or forming a first middle module to a first longitudinal length and selecting one each of the substantially identical front and rear modules. A first frame, having a first frame length, is then assembled from the formed first middle module and substantially identical front and rear modules. After forming another middle module to a second length; a second frame, having a second frame length different from the first, may then be assembled from the second formed middle module and a second pair of substantially identical front and rear modules. 
     An assembly having flexible modular architecture is also provided. Substantially identical front and rear frame modules of predetermined, fixed lengths form the common base for all assembled vehicle frames. By mating these substantially identical front and rear modules to a mid frame module having parallel longitudinal members that can be easily formed to myriad lengths and have a constant cross section, the assembly is capable of producing vehicle frames of variable lengths from largely fixed-length components. The front and rear structural frame attachment interfaces which facilitate mating of the components are capable of mating to the formable mid frame module, regardless of the length to which it is trimmed or formed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevated view of an embodiment of a modular body-on-frame architecture, including front, middle and rear modules; 
         FIG. 2  is a front view of the middle module of  FIG. 1 ; 
         FIG. 3  is a side view of multiple frames assembled from the modular body-on-frame architecture of  FIG. 1 ; 
         FIG. 4  is an elevated view of an embodiment of a modular body-on-frame architecture having two rear modules; and 
         FIG. 5  is a side view of two rear pickup modules, having modular bracket sets attached in first and second configurations. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, wherein like reference numbers correspond to like or similar components throughout the several figures, there is shown in  FIG. 1  an embodiment of a modular body-on-frame architecture  8 . Vehicles of different overall body length require different wheelbases and different attachment points for the vehicle body (containing the passenger and cargo compartments). In order to accommodate multiple body lengths, previous body-on-frame designs had to have a unique frame for each wheelbase variation, and a unique frame for each body-type variation. Thus small sport-utility vehicles, small pickup trucks, medium utilities, and medium pickups all had to have unique frames built from unique components. This invention presents a method and assembly allowing each of these body variations (and many others) to be built from shared components, with only slight variations. Note that while  FIG. 1  shows only a single set of the components (modules) used to assemble a vehicle frame, the method and assembly described herein envision larger quantities of both frame modules and completed frames. From a limited number of common components, created from shared engineering and tooling resources, multiple platforms can be accommodated by the modular body-on-frame architecture  8 . 
     As used in reference to the drawings, and throughout the specification and appended claims, terms such as “front,” “middle,” and “rear” are used to describe corresponding portions of a vehicle, such as an automobile, as will be recognized by those familiar with automobiles. However, terms such as “left,” “right,” “down,” and “up” are used only descriptively of relative directions in the drawings themselves. 
     The modular body-on-frame architecture  8  of  FIG. 1  is comprised of three frame modules which can be assembled to create a single vehicle frame having a variety of frame lengths. At the front of the vehicle (on the left, as viewed in  FIG. 1 ) is a front module  10 . A substantially identical front module  10  is common to all frames made from the modular body-on-frame architecture  8 . Front module  10  is generally composed of front longitudinal members  12  transversely spaced by front cross members  14 . On the rearward end of each of the front longitudinal members  12  is a front-to-middle frame interface  16 . 
     At the rear of the vehicle (on the right, as viewed in  FIG. 1 ) is a rear pickup module  20 . One of two rear module variations is common to all frames made from the modular body-on-frame architecture  8 ; the other variation, a rear sport-utility module  28  will be discussed in more detail below, and is shown in  FIG. 4 . Rear pickup module  20  is generally composed of rear longitudinal members  22  transversely spaced by rear cross members  24 . On the forward end of each of the rear longitudinal members  22  is a rear-to-middle frame interface  26 . The front-to-middle frame interface  16  and rear-to-middle frame interface  26  have substantially equal transverse spacing between their respective longitudinal members  12  and  22 . The front-to-middle and rear-to-middle frame interfaces  16  and  26  are structures configured to be mated to the middle module  30 . 
     Those having ordinary skill in the art will recognize myriad processes by which frame modules can be manufactured for use in the modular body-on-frame architecture  8 . Possible forming methods include, without limitation: roll-forming, stamping, hydroforming, extrusion, or combinations thereof. 
     In between the front module  10  and the rear pickup module  20  is the middle module  30 . The middle module  30  is generally composed of parallel, constant-section longitudinal rails  32  transversely spaced by a distance substantially equal to the transverse spacing between the frame interfaces  16  and  26 . Middle module  30  may be transversely separated by one or more middle cross members  34 . “Constant-section” refers to the characteristic that if cut along any plane perpendicular to the constant-section longitudinal rails  32 , the rails have a substantially identical profile; i.e. the rails are straight with a uniform cross section. Middle module  30  allows vehicle frames assembled from the modular body-on-frame architecture  8  to achieve variable lengths even though the frames are assembled from common modules. The constant-section longitudinal rails  32  allow the middle module  30  to be produced with a single tool, but still be formable to variable lengths.  FIG. 2  shows the middle module  30  from a front view perspective. Viewed from front, the middle module  30  looks substantially the same whether made to a length of 12 inches or 48 inches. 
     Those having ordinary skill in the art will recognize various methods of creating middle modules  30  of varying lengths with a single tool or die. Possible methods include, without limitation: over-sizing and trimming, roll forming, and short-sheeting. Over-sizing and trimming involves creating multiple longitudinally-oversized modules from a large die, each of which can then be trimmed down to the desired final length. Creating longitudinally-oversized modules, however, may increase costs of the operation by creating waste (from the trimmed-away portions). Roll-forming is a continuous bending operation in which a long strip of metal is passed through consecutive sets of rolls, each performing only an incremental part of the bend, until the desired cross-section profile is obtained. Roll-forming allows modules to be created to substantially final lengths, does so with low amounts of waste, and also offers reduced tooling costs. Both pre-cut and post-cut roll-forming may be suitable for creating middle modules cut to the desired length. Where post-cut roll-forming is used, the roll-formed pieces are cut or trimmed to length at the end of the continuously-feeding process. Short-sheeting involves inserting blanks into the ends of the oversized die to reduce the effective length of the die, and thereby forming a middle module  30  that is essentially the desired length right out of the die. Both roll-forming and short-sheeting result in modules that are pre-sized for specific applications. 
     Because the constant-section longitudinal rails  32  do not substantially change cross-section throughout the formable or trim-able portion, the interface structures needed to attach to the middle module  30  are the same regardless of the longitudinal length chosen (or the method by which it was created). Therefore, front-to-middle frame interface  16  and rear-to-middle frame interface  26  may be mated to a middle module  30  of any formed or trimmed length. 
     In order to implement any truly-modular body-on-frame architecture into actual automotive production, significant manufacturer-specific design work must be put into determining the location of the interface structures. Front-to-middle frame interface  16  and rear-to-middle frame interface  26  must be strategically placed to accommodate the many different body types and sizes to which the modular body-on-frame architecture  8  will be applied. Variations in passenger compartments, cargo compartments, engine types and sizes, front and rear suspensions, fuel tanks, and driveline configurations all require that the interface structures  16  and  26 —and therefore the formable middle module  30 —be placed with great precision. Only with proper placement of the interface structures can multiple platforms be accommodated by a single modular body-on-frame architecture. 
       FIG. 3  shows a side view of multiple vehicle frames assembled from the modular body-on-frame architecture  8 . To better illustrate the assembly process, some of the frames are shown whole, and some without front modules. The frames of  FIG. 3  are assembled using multiple middle modules  30  of varying lengths created with a single tool or die; middle modules  30   a,    30   b,    30   c,    30   d,    30   e,    30   f.  The method of assembling vehicle frames from the modular body-on-frame architecture  8  involves first selecting a set of the required components and then assembling the components into the individual frames. A typical first selection of components for a first assembled frame  50  would include selecting a front module  10  from a provided inventory or flow of substantially identical front modules  10 , which are common to all assembled frame lengths. Next, either a rear pickup module  20  or a rear sport-utility module  28  would be selected from a provided inventory or flow of one or both of these rear module variations; the specific rear module selected does not alter the method. Selection of the middle module  30   a  determines the overall length of the assembled frame. Either the pre-sized middle module  30   a  may be selected, or an oversized middle module  30  may be trimmed to the desired size. As shown in  FIG. 3 , the first selected middle module  30   a  has a first longitudinal length M 1 . 
     The first assembled frame  50  is assembled by joining the front-to-middle frame interface  16  to a first end  36  of the middle module  30   a,  and joining the rear-to-middle frame interface  26  (which is identical on either the rear pickup module  20  or rear sport-utility module  28 ) to an opposing end  38  of the middle module  30   a.  The modules can be joined by any method known to those skilled in the art, such as, without limitation: welding, adhesives, fasteners, or another method of bonding. The result is the first assembled frame  50 , which has a first frame length L 1 . 
     The method of assembling a second assembled frame  52  is largely identical to the first assembled frame  50 . Another, identical, front module  10  and another, identical, rear pickup module  20  are selected from the respective inventories. When a second middle module  30   b  is selected from the inventory, it is either trimmed to a second longitudinal length M 2 , which is different from the first longitudinal length M 1  used in the first assembled frame  50 , or a pre-sized middle module having a second longitudinal length M 2  is selected. Because all of the middle modules  30  have constant-section longitudinal rails  32 , attachment of the middle module  30   b  to the front module  10  and rear pickup module  20  is done with a similar process to that used in assembling the first assembled frame  50 . After the frame interfaces  16  and  26  are joined to the ends  36  and  38  of the middle module  30   b  having the second longitudinal length M 2 ; the result is the second assembled frame  52 , which has a second frame length L 2 , different from the first frame length L 1 . 
     Third and fourth assembled frames  54  and  56  are similarly assembled using the above described method. Third and fourth frame lengths L 3  and L 4  are achieved by selecting middle modules  30   c  and  30   d  with third and fourth longitudinal lengths M 3  and M 4 . As shown in  FIG. 3  and described above, the common components of the modular body-on-frame architecture  8  shown in  FIG. 1  have created four distinct assembled frames having four different frame lengths, L 1 , L 2 , L 3  and L 4 ; and can be assembled into innumerable other frame lengths. Each of the components used in the modular body-on-frame architecture  8  is created with shared engineering and tooling solutions while retaining expansive modularity. This ability to create multiple distinct frames from identical components makes the modular body-on-frame architecture  8  capable of achieving substantial manufacturing and production cost savings. 
     A possible further, and similar, variation in the rear pickup module is shown on fifth and sixth assembled frames  58  and  60 , which are assembled using middle modules  30   e  and  30   f,  and an extended rear pickup module  40 . The extended rear pickup module  40  has a longer overhang, allowing a longer pickup bed to be included on the final vehicle. These extended rear pickup modules  40  are nearly identical to the standard rear pickup modules  20 , except that the rear longitudinal members  22  are extended by overhang distance R. This extension R is achieved along the constant-section portion of the rear longitudinal members  22 , which allows rear pickup module  20  and extended rear pickup module  40  to be manufactured using the same dies. A single set of dies are tooled to allow for the longest possible rear module length—extended rear pickup module  40 —and the die can be short-sheeted to create a module having a smaller standard overhang—the rear pickup module  20 . 
       FIG. 4  shows an embodiment of the modular body-on-frame architecture  8  of  FIG. 1 , this figure shows both rear module alternatives side by side. In order to accommodate the different body style of sport-utility vehicles, which have integrated passenger and cargo compartments, a preferred embodiment of the modular body-on-frame architecture  8  includes an alternative rear module, the rear sport-utility module  28  mentioned above. As shown in  FIG. 4 , rear sport-utility module  28  is very similar to rear pickup module  20 . Rear sport-utility module  28  is also composed of rear longitudinal members  22  and rear cross members  24 , and has the same rear-to-middle frame interface  26 . One difference in rear sport-utility module  28  lay in the slightly different paths of the non-constant-section portions of the rear longitudinal members  26 , which allow for attachment of the sport-utility body. Alternative rear modules also allow for differences in the rear structure required for different types of suspension. 
     Even after accommodating such a wide spectrum of wheelbase variations and body types, the need to accommodate multiple suspension types might require further design flexibility. Suspension needs vary widely over the spectrum of small to large utility and pickup truck applications, and may even vary within model lines. Differences in vehicle weight, towing capacity, and desired ride and handling characteristics make it nearly impossible for a single type and size of suspension to be used in all of the myriad vehicles to which the modular body-on-frame architecture  8  may be applied. To overcome this problem, the modular body-on-frame architecture  8  includes a modular bracket set  42  which is configured to be attached to any of the rear modules  20 ,  28 , or  40 ; and can be attached in multiple locations, creating frame and bracket configurations which allow variation of attachment points for the suspension and other components. 
       FIG. 5  shows two substantially identical rear pickup modules  20  with different modular bracket set configurations. The upper (as viewed in  FIG. 5 ) pickup module  20  has a first configuration of the modular bracket set  42 , and the lower pickup module  20  has a second configuration, denoted  42 ′. Attachment of the modular bracket set  42  may be accomplished by any method known to those skilled in the art, such as, without limitation: welding, adhesives, fasteners, or another method of bonding. 
     The frame and bracket configurations created with the modular bracket set  42  add yet another degree of freedom to the modular body-on-frame architecture  8 , further expanding the possible range and size of vehicles created using these simple components and method of assembly. From a limited number of common components, created from shared engineering and tooling resources, multiple platforms can be accommodated by the modular body-on-frame architecture  8 . 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.