Patent Publication Number: US-6665935-B2

Title: Method of making a vehicle chassis of extruded links and couplers

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. application Ser. No. 09/625,593 filed Jul. 26, 2000 now U.S. Pat. No. 6,470,990. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a method of making a chassis for a vehicle and to a chassis made with extruded beams that are connected by extruded couplers. 
     BACKGROUND OF THE INVENTION 
     A chassis is the backbone of a vehicle that provides a durable frame to which the body, drive train and other parts of a vehicle are assembled. A conventional vehicle chassis is formed of welded, stamped or forged steel beams that add considerable weight to a vehicle. With conventional steel chassis, it is a constant challenge to consistently form and assemble the chassis parts to meet close tolerances. The weight of a conventional chassis adversely impacts fuel economy. Recently, efforts have been made to eliminate conventional steel chassis. 
     One approach that addresses the disadvantages of a separate conventional steel chassis is the development of uni-body construction techniques wherein frame members are formed integrally with body parts that are assembled together to form the frame. With uni-body construction, different modules are integrally formed with portions of the frame that are then linked together by fasteners or welding. One challenge encountered with a uni-body type chassis includes maintaining close tolerances for proper vehicle fit and finish requirements. In the event that a uni-body vehicle is involved in a collision, it may be difficult or impossible to straighten the integral frame without adversely impacting other body panels. 
     Space frame construction techniques use welded steel or aluminum tubular members that are assembled together to manufacture some vehicles. However, space frame vehicles tend to be expensive to manufacture due to labor costs and extensive fixturing required to meet tolerances. One recent development relating to space frames is disclosed in U.S. Pat. No. 5,947,519 that proposes the use of specialized nodes to which frame rails are welded. The ends of frame members are peripherally welded to the node during the assembly process. Welding aluminum is a relatively expensive process requiring special aluminum welding rods. Welding causes localized heating of the rails and nodes that can result in deformation of chassis parts. Also, the approach disclosed in this patent does not provide an easy way to align frame rails to assure maintenance of close tolerances without the use of expensive assembly fixtures. 
     The present invention addresses the above problems and shortcomings of the prior art and provides a simple method of making a chassis and an improved chassis construction with additional benefits and advantages as summarized below. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a method of manufacturing a chassis for a vehicle is provided. The method comprises extruding a plurality of beams, the beams having walls defining an internal surface. Beams are formed in different lengths depending upon the size of the chassis to be built. A plurality of couplers are extruded and have at least two generally horizontally extending receptacles sized to fit within the walls of the beam. Each coupler has a generally vertically oriented pocket formed between the receptacles. The couplers are assembled between beams by assembling the beams and couplers together loosely and to a fixture. The fixture has locating pins located at predetermined locations that are received in the pockets of the couplers. The beams and couplers are then permanently affixed to each other to form the chassis. 
     The step of securing the beams and couplers together is preferably performed by applying an aluminum bonding cement between the receptacles of the couplers and the beams. Alternatively, the beams and couplers could be secured together by forming holes in the ends of the beams and in corresponding locations on the couplers and inserting fasteners through the holes. The beams and couplers can also be assembled together by means of both cement and mechanical fasteners to provide a redundant securing system that may be desirable in some applications. 
     According to another feature of the present invention, the couplers are preferably extruded so that the receptacles have a closed end that is first inserted into one of the beams. 
     According to another aspect of the present invention, the couplers and/or beams may be formed with a recess having ribs extending in the direction of extrusion formation to facilitate the flow of cement between the receptacles and the beam. The ribs provide additional bonding surface area and additional surface structure that enhances bond strength. 
     According to yet another aspect of the present invention, the step of extruding the couplers may further include the step of extruding the coupler to form a pillar of the vehicle that extends upwardly from the beams that are joined by the coupler. The receptacle is separated from the pillar by cutting away a portion of the coupler for receiving a wall of the beam. 
     The method of the present invention may also include, as part of the step of extruding the coupler, forming a stop rib on the receptacles at the juncture of the receptacles and the central portion of the coupler. 
     The present invention also comprehends a chassis for a vehicle that is formed in five modules. A center chassis module is provided to which the fire wall bulkhead of the vehicle and passenger compartment of the vehicle are secured. A drive train and front suspension module is provided to which the engine, transmission and front suspension components are attached. The drive train module is secured to the front end of the center chassis module. The rear suspension and gas tank are secured to the rear suspension module. The rear suspension module is secured to the rear end of the center chassis module. A front crush module is attached to the drive train and front suspension module and includes a front bumper assembly. A rear crush module, including a rear bumper assembly, is separate from but secured to the rear suspension module. The chassis from front to rear includes the front crush module, the drive train and front suspension module, the center chassis module, the rear suspension module and the rear crush module. 
     According to the present invention, a passenger compartment trim ring may be provided as part of the vehicle that is assembled to the drive train and front suspension module, center chassis module and rear suspension module. The trim ring is a mid-body superstructure that forms a combined dashboard, two rocker panel covers and a well for a convertible top of the vehicle. 
     The unique modular chassis of the present invention is formed by at least one transverse rear beam that is connected on opposite sides to two rear couplers. Two side beams are connected on their back ends to each of the two rear couplers and two front couplers are connected to the front ends of each of the two side beams. Two convergent front beams are connected to the front couplers on their outer back ends and to the drive train and front suspension module on their forward ends. 
     According to yet another aspect of the present invention, the rear beam is preferably formed in two sections that are joined to a central drive shaft tunnel bracket. 
     A pair of hinge pillars may be assembled to the front couplers with one hinge pillar being secured to each of the front couplers to extend upwardly to the base of the windshield frame. 
     According to another aspect of the present invention, the couplers may connect adjacent beams in a range of angular orientations from 0 to 180 degrees. However, the couplers may connect beams at approximately 90 degrees or approximately 135 degrees. By approximately, it is intended that the angular orientations be within 15 degrees of 90 or 135 degrees. 
     According to another unique feature of the invention, the coupler may include a pillar of the vehicle that extends upwardly from the receptacle. The pillar is formed above the receptacle of the coupler over which the beam is received. 
     A further aspect of the invention is the concept of forming a stop rib on the receptacles of the couplers at the juncture of the receptacles and the central portion of the coupler. 
     Another feature of the present invention relates to the structure and function of the coupler used in forming the chassis. The coupler includes a central portion having an outer wall and a plurality of inner walls extending inwardly from the outer wall to a pocket that is connected to the inner walls. At least two receptacles are connected to and extend outwardly from the central portion. The receptacles are dimensioned to be received in the central opening of one of the extruded beams. The central pocket is adapted to be placed on a locating pin of a fixture that is used to align the coupler with the extruded beams and other couplers. The central opening in the extruded beam may be rectangular in shape and that the receptacles would in turn be rectangular in shape having a closed end that is formed as an extruded wall on the opposite side of the receptacle from the central portion. The receptacle also includes two side walls that are formed as extruded walls connecting the end wall to the central portion. 
     As explained above in the context of the chassis construction, the couplers may be formed with a wide variety of angular relationships between receptacles. The couplers may include recesses having ribs extending in the direction of the extrusion to facilitate flow of cement and augment bonding as described above. Likewise, the coupler may include a pillar of the vehicle that extends upwardly from the receptacle. The couplers may include stop ribs formed on the receptacles. 
     These and other advantages and features of the present invention will be apparent to one of ordinary skill in the art in view of the attached drawings and following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of a vehicle chassis made in accordance with the present invention. 
     FIG. 2 is a perspective view of a vehicle chassis made in accordance with the present invention. 
     FIG. 3 is an exploded perspective view of a center chassis module and rear suspension module made in accordance with the present invention. 
     FIG. 4 is an exploded perspective view of a center chassis module, rear suspension module and trim ring made in accordance with the present invention. 
     FIG. 5 is an exploded perspective view of the components shown in FIG. 4 shown with a drive train and front suspension module in accordance with the present invention. 
     FIG. 6 is an exploded perspective view of a partially assembled vehicle body made in accordance with the present invention. 
     FIG. 7 is a perspective view of a center chassis module made in accordance with the present invention. 
     FIG. 8 is a perspective view of a drive train and front suspension module made in accordance with the present invention. 
     FIG. 9 is a perspective view of a rear suspension made in accordance with the present invention. 
     FIG. 10 is a perspective view of a right angle coupler and a fragmentary perspective view of a beam in exploded perspective. 
     FIG. 11 is a perspective view of an oblique angle coupler and fragmentary perspective view of a beam in exploded perspective. 
     FIG. 12 is a perspective view of an oblique angle pillar/coupler. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Referring now to FIGS. 1 and 2, a chassis  10  made in accordance with the present invention is shown. The chassis  10  includes a center chassis module  12 . A drive train and front suspension module  14  is attached at the forward end of the center chassis module  12 . A rear suspension module  16  is attached to the rear of the center chassis module  12 . A front crush module  18  is attached to the front of the drive train and front suspension module  14 . A rear crush module  20  is attached to the rear suspension module  16 . Each module may be separately assembled as a module and then attached to each of the other modules to form a chassis  10 . 
     A fire wall bulkhead  24  is attached to the center chassis module  12 . A specialized vehicle may be manufactured utilizing many components from a production vehicle and, in particular, many components relating to the drive train and instrument panel. In this way, vehicle controls, heating, ventilation and air conditioning and drive train components may be assembled to the chassis in a modular approach, thereby minimizing modifications to the production vehicle components and systems. The passenger compartment  26  of the vehicle is built on the center chassis module  12 , while the engine  26  and transmission  28  of a production vehicle are assembled to the drive train and front suspension module  14 . 
     The front suspension  32 , preferably an independent coil spring suspension, is connected to the drive train and front suspension module  14 . The rear suspension  34  is secured to the rear suspension module  16 . A fuel tank  36  is also connected to the upper portion of the rear suspension module  16 . A front bumper  40  is connected to the front crush module  18 . A rear bumper  42  is secured to the rear crush module  20 . The front and rear bumpers  40  and  42 , respectively, are preferably formed as curved extruded aluminum members. 
     Referring to FIGS. 3-6, a series of steps in the chassis manufacturing process are shown in sequence. In FIG. 3, the center chassis module  12 , rear suspension module  16  and fire wall bulkhead  24  are shown ready for assembly. 
     Referring to FIG. 4, the parts shown in FIG. 3 are assembled and a trim ring  46  is shown ready for assembly to the components of FIG.  3 . The trim ring  46  is a monolithic structure that extends around the passenger compartment. The trim ring  46  comprises a dashboard  48 , two running boards  50  extending on opposite sides rearwardly from the dashboard, and a convertible top well  52  interconnects the rear ends of the running boards  50 . While a convertible top well  52  is shown, if the vehicle to be assembled is a hardtop, a package tray would be included instead of the convertible top well  52  as part of the trim ring  46 . The trim ring  46  serves to tie together the modules forming the passenger compartment assuring acceptable fit and finish of the components making up the passenger compartment. 
     Referring now to FIG. 5, the parts shown in FIG. 4 are assembled and the drive train and front suspension module  14  is shown ready for assembly to the components of FIG.  4 . 
     Referring now to FIG. 6, body panels of the vehicle are assembled to the chassis. 
     Referring now to FIG. 7, the standard chassis module  12  is described in detail. A rear beam  54  is preferably formed in two parts that are connected to a drive shaft tunnel bracket  56 . The drive shaft of the vehicle extends through the drive shaft tunnel bracket  56  to connect the rear axle differential (not shown) to the vehicle transmission  28 . On opposite lateral ends of the rear beam  54 , rear couplers  58  are provided. Rear couplers  58  are connected to the opposite ends  60  of the rear beam  54 . Rear couplers  58  connect the rear beam  54  to side beam  62 . The back end  64  of the side beams  62  are received on the rear couplers  58 . Front couplers  66  are assembled to the front end  68  of the side beam  62 . Convergent beams  70  are connected to the front couplers  66  on their outer back end  72 . The forward and inward ends of the convergent beams  70  are attached to drive train plate  76  on the inner front end  78  of the convergent beams  70 . 
     It should be understood that couplers could be extruded having any angular orientation between the beams joined by the couplers depending upon the design of the vehicle. The rear couplers  58  join the rear beam  54  to the side beam  62  in a right angle relationship. Front couplers  66  in illustrated embodiment join the side beam  62  to the convergent beams  70  at an angular relationship of approximately 135 degrees. This angular relationship could be changed depending upon styling and vehicle design considerations. Also, the length of the rear beam  54  can be modified to change the width of the vehicle, while the length of the side beam  62  or convergent beams  70  could be modified to change the length of the vehicle and size of the passenger compartment. 
     Referring now to FIG. 8, the drive train and front suspension module  14  is shown in isolation. A pair of engine support beams  80  extend in a forward direction from the drive train plate  76  and are provided with brackets and plates for mounting the engine and also mounting the front crush module  18 . By providing a front crush module  18  that is separate from the drive train and front suspension module  14 , it is possible to minimize damage to the vehicle in the event of a front end collision by designing the front crush module  18  to absorb the energy of an impact. The front crush module  18  then may be replaced separate from the drive train and front suspension module  14  facilitating repair and reconstruction of the vehicle. 
     Referring now to FIG. 9, the rear suspension module  16  is shown in isolation. The rear suspension module  16  supports the gas tank for the vehicle and the rear suspension  34 . Rear suspension  34  is preferably an independent rear suspension. The rear crush module  20  is attached to plates  82  that are part of the rear suspension module  16 . The separate rear crush module  20  reduces repair and reconstruction costs in the event of a rear collision similar to the front crush module  18  as described above. 
     Referring to FIGS. 1,  2  and  3 , hinge pillar  84  is shown interconnecting the center chassis module  12  to the fire wall bulkhead  24 . 
     As shown in FIG. 6, a windshield  86  is assembled to the fire wall bulkhead  24  that is shown to include the windshield frame  87 . Seats  92  are assembled to the center chassis module  12  in the passenger compartment  26 . 
     Referring now to FIGS. 10 and 11, an example of a rear coupler  58  and a front coupler  66  are illustrated in the respective figures. The same reference numerals are used for similar parts of the couplers. 
     Each coupler has a central portion  94  having an outer wall  96  and inner walls  98  connecting the outer wall  96  to a pocket  100 . Each coupler has two receptacles  104  that extend from the central portion  94  at a predetermined angular orientation. In FIG. 10, the angular orientation is 90 degrees or a right angle. In FIG. 11, the angular orientation of the receptacles  104  relative to the central portion  94  is 135 degrees. The receptacles  104  have closed end walls  106  and side walls  108 . Each type of coupler is preferably extruded as a single extrusion and cut to the desired size. 
     The couplers are assembled together with beams and located on a fixture  112  having a locating pin  114 . The fixture  112  is only partially shown in FIG.  10  and would include locating pins  114  for each of the pockets  100  on the several couplers of the chassis. The beams are loosely assembled together with the couplers and placed on the fixturel  12  that precisely locates the couplers. 
     Holes  116  are provided in the receptacles  104  for receiving fasteners  118  that may be used to secure the couplers to the beams. Inner walls  120  are provided within the receptacles  104  to reinforce the receptacles  104  and provide structure to define the holes  116 . 
     A glue recess  122  may be formed on the coupler. Another glue recess  124  may be provided on the beam. The purpose of the glue recess is to provide space for receiving aluminum bonding cement between the couplers and the beams. As the couplers and beams are formed, vertical ribs  126  may be formed in the glue recess  122  on the coupler and longitudinal ribs  128  may be formed in the glue recess  124  on the beam. Stops  130  may be provided adjacent or near the junction of the receptacles  104  and the central portion  94  to align the beam on the coupler. 
     The beams include horizontal walls  132  and vertical walls  134 . Holes  136  may be provided in the horizontal walls of the beam  132  for receiving the fastener  118 . Glue injection holes  138  are provided in the vertical walls  134  of the beam. Glue is injected into one of the glue injection holes  138  and caused to flow into the space between the beam and the receptacle  104 . If the glue recesses are provided on the coupler and the beam and ribs are provided as previously described, glue injected into the holes  138  may fill the recesses and adhere to the ribs to provide a high strength attachment mechanism. 
     Referring now to FIG. 12, a pillar/coupler  140  is shown that combines the coupler with one of the A, B or C pillars of the vehicle. The A pillar may also be referred to as a hinge pillar and is the pillar immediately below the windshield frame to which the hinges of the front doors of the vehicle are attached. The B pillar is the mid-passenger compartment pillar to which the front doors of the vehicle close and for sedan vehicles is the pillar on which the rear door hinges are mounted. The C pillar is provided on sedans in the back portion of the passenger compartment and is the pillar to which the rear doors are closed. 
     The pillar/coupler  140  shown in FIG. 12 is initially formed as a single extrusion. The extrusion is then cut away to form a pillar portion  142 . A lower coupler portion  144  is provided when the pillar portion  142  is formed. The height of the lower coupler portion  144  is cut to the height necessary to accommodate assembly of the side or other rail section. The upper coupler portion  146  is also formed when the extrusion is cut away to form the pillar portion  142 . The upper coupler portion  146  may be assembled to a cross car beam in a manner similar to which the beams are connected to the lower coupler. A hinge mounting surface  152  may be provided on the rear facing surface of the pillar/coupler  140  to permit mounting the door hinges of the doors of the vehicle on the pillar coupler  140 . 
     While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and 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.