Motor vehicle having a side sill

[0001] This application is a continuation of PCT International Application No. PCT/EP2006/001261, filed Feb. 11, 2006, which claims priority under 35 U.S.C. § 119 to German Patent Application No. 10 2005 009 162.8, filed Feb. 25, 2005, the entire disclosures of which are herein expressly incorporated by reference.

[0002] The invention relates to a motor vehicle having a side sill made of sheet metal, having an inner shell connected to an outer shell by upper and lower flanges.

[0003] Use of an inner shell and an outer shell to construct a side sill of a motor vehicle according to shell construction is generally known. For cost reasons the outer shell is frequently designed as one piece with a side wall of the motor vehicle. The side wall typically extends from the side sill to the roof side frame, and at least over the entire side door aperture of the motor vehicle.

[0004] In recent times, use of high-strength sheet steel has become more prevalent in body construction for the purpose of reducing weight and increasing rigidity. However, high-strength sheet steel permits only slightly more shaping than conventional sheet steel before reaching its yield point. During deep-drawing of high-strength sheet steel, the yield point is reached at comparatively small shaping paths. High-strength sheet steel tears when shaping is performed beyond the yield point. For this reason, until recently it was not possible to manufacture side walls having an integrated outer shell of the side sill from high-strength sheet steel, since the permissible shaping paths are too small.

[0005] A method is known from German Patent Document DE 101 28 989 A1 for forming a side wall as one piece with an outer shell of a side sill from high-strength sheet steel. In this case, the side wall merges without gradation into the adjoining side sill in the region of at least one vehicle pillar. As a result of the gradation being omitted, and therefore as a result of the lack of unrestricted overstrain of the sheet steel during the drawing process, the sheet steel is subjected to significantly less strain. Therefore, sheet steel having a higher yield point may be used.

[0006] The exemplary embodiments of the invention describe methods and systems to produce a motor vehicle having a side sill of shell construction which is partially formed by a side wall which may be composed of high-strength sheet steel.

[0007] According to an embodiment of the invention, a motor vehicle has a side sill of sheet metal shell construction having at least one inner shell and one outer shell which are connected to one another by an upper and a lower flange. The exemplary outer shell may be formed by the lower section of a side wall to which an outer panel is attached for providing a downward extension, so that the inner shell and the outer panel are connected to one another in the lower flange. The inner shell and the side wall thus are connected to one another in the upper flange.

[0008] The drawing depth required for a side wall having an integrated outer shell of a side sill is determined primarily by the width of the side sill. As a result of the division of the outer shell of the side sill on the side wall and a separate outer panel, only very small drawing depths are necessary for the side wall, regardless of the shape and width of the side sill. The shape and width of the side sill essentially affect only the shape and drawing depth of the outer panel. For this reason, the exemplary side wall may have small drawing depths of less than 85 mm, independent of the design of the side sill. This allows the use of sheet steel of high material quality for the side wall, having an Rp02 yield point of, for example, about 160 MPa or greater. On account of the smaller draw depth, the manufacture of the side wall is simplified to the extent that even the panel thickness of the side wall may be reduced. Thus, for example, panel thicknesses of about 0.7 mm and less may be achieved. The material quality and thickness of the outer panel may be functionally designed independently of the side wall. On the whole, the division of the outer shell of the side sill on the side wall and the separate outer panel afford greater design flexibility. Thus, the width of the side sill is no longer limited by manufacturability concerns, and the side sill may have localized drawn-in areas.

[0009] The side wall and the outer panel, according to an embodiment of the invention, preferably form an overlap region in the form of a connecting flange. Multiple spot welding connections are particularly suited for joining the side wall to the outer panel.

[0010] The side sill may be advantageously cladded with a panel on the visible vehicle exterior. For this reason the outer panel need not have attractive visible surfaces of appropriate surface quality. In addition, the connecting flange between the side wall and the outer panel is no longer visible, and is protected from the effects of dirt and water spray. The panel may be designed as a plastic component, for example.

[0011] Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

[0015] FIG. 1 shows a cross section of an exemplary side sill 1 of a passenger vehicle in the region of a side door 2. The side sill 1 is composed of an inner shell 3 and an outer shell built according to shell construction. The outer shell may be formed by the lower region of a side wall 4 of the vehicle body and an outer panel 5. As illustrated in FIG. 2, the side wall 4 may extend in the longitudinal direction from an A-pillar 13 over the B- and C-pillars 14 and 15, and at the same time forms a rear fender 16 of the passenger vehicle. The side wall may extend vertically from the region of the side sill 1 to the roof side frame 17. As shown in FIG. 1, at the side sill 1 the side wall 4 and the outer panel 5 are connected to one another, for example, by a connecting flange 6 formed in the lower region of the side wall 4 via spot weld connections, thus forming the outer shell. The inner shell 3 and the outer shell 4, 5 are connected to one another, for example, by using an upper flange 7 and a lower flange 8. The side wall 4 may be connected to the inner shell 3 in the upper flange 7, whereas the outer panel 5 is connected to the inner shell 3 in the lower flange 8. On the underside of the side sill 1, in the respective front and rear regions, a recess is provided in the outer panel 5 in which a jack receptacle 10 may be formed.

[0016] To enable absorption of the forces transmitted via the jack receptacle 10 to the side sill 1 when the vehicle is jacked up, in the vicinity of the jack receptacle 10 the outer panel 5 may be reinforced with a two-piece reinforcement panel 9, which at one end is connected to the outer panel 5 and the inner shell 3 in the lower flange 8, and at the other end is connected to the outer panel 5 in the connecting flange 6. Between the jack receptacle 10 and the connecting flange 6 the reinforcement panel 9 is spaced at a distance from the outer panel 5. For purposes of weight reduction the reinforcement panel 9 also can have multiple recesses. For reinforcement, on the side of the inner shell 3 facing the outer shell 4, 5 an auxiliary panel 11 may be mounted which extends in the longitudinal direction of the side sill 1, and which, at its upper and lower edge regions is connected to the inner shell 3, and between these points is separated at a distance from the inner shell 3. The part of the side sill 1 visible from the vehicle exterior may be cladded with a trim panel 12 made of plastic.

[0017] In contrast to a known side wall, into which the outer shell of a side sill is completely integrated, a much smaller draw depth is necessary for the illustrated exemplary side wall 4. The required draw depth for the known side wall is determined chiefly by the width and shape of the side sill. As a result of the exemplary division of the outer shell according to the invention into the side wall 4 on the one hand and the outer shell 5 on the other hand, the required draw depth for the side wall 4 is significantly reduced. The width and shape of the side sill 1 affects almost exclusively the shape, thickness, and material quality of the outer panel 5. Due to the smaller draw depth for the side wall 4, the side wall may be manufactured from high-strength sheet steel having yield points of about 160 MPa or greater. As a result, the sheet thickness of the side wall 4 in turn may be reduced to about 0.7 mm, for example. Notwithstanding, this configuration does not result in manufacturing limitations for the design of the side sill 1. The material quality and sheet thickness of the outer panel 5 may be set independently of the side wall 4. The requirements for surface quality of the outer panel 5 are low, since the outer panel 5 is not visible, but instead is concealed on the vehicle by the panel 12. In addition, the same outer panel 5 may be used for various body variants, for a sedan and a station wagon-type vehicle, for example. Furthermore, the outer panel 5 may be combined with the reinforcement panel 9 as a prefabricated module, which likewise may be the same for multiple body variants.

[0018] The exemplary side sill 1 according to embodiments of the invention thus allows great freedom in the shaping of the side sill. The side wall 4 may be made of high-strength sheet steel, thus allowing the weight of the body of the passenger vehicle to be kept low. The rigidity requirements for the side sill 1 may be easily satisfied by a suitable selection of material for the outer panel 5.

[0019] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.