Under frame of a motor vehicle

摘要

An underframe of a motor vehicle includes side sill frames extending along and at opposite sides of a floor portion of a passenger compartment, and tunnel frames extending in the same direction as and interposed between the side sill frames. Each of the side sill frames and tunnel frames has a top-open channel configuration. Front side frames are also provided with a top-open channel configuration. Straight portions of the side sill frames and tunnel frames are individually connected at their front ends to the front side frames by top-open channel-like connecting portions such that the channels of those frames are communicated to each other. The underframe having such a structure is easy to produce and provided with extreme rigidity and strength.