Patent Application
20090236877
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.
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.
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.
Referring to the drawings, wherein like reference numbers correspond to like or similar components throughout the several figures, there is shown in
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
At the rear of the vehicle (on the right, as viewed in
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.
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.
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 30a, 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 30a. 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 L1.
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 30b is selected from the inventory, it is either trimmed to a second longitudinal length M2, which is different from the first longitudinal length M1 used in the first assembled frame 50, or a pre-sized middle module having a second longitudinal length M2 is selected. Because all of the middle modules 30 have constant-section longitudinal rails 32, attachment of the middle module 30b 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 30b having the second longitudinal length M2; the result is the second assembled frame 52, which has a second frame length L2, different from the first frame length L1.
Third and fourth assembled frames 54 and 56 are similarly assembled using the above described method. Third and fourth frame lengths L3 and L4 are achieved by selecting middle modules 30c and 30d with third and fourth longitudinal lengths M3 and M4. As shown in
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 30e and 30f, 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.
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.
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.
