US Patent 6866443 Fastening assistance structure

A fastening assistance structure has a bolt hole for passing therethrough a threaded portion of a bolt, a seat face for engaging a head seat face of the bolt, and a partition wall for guiding the bolt into the bolt hole. A bolt inlet which is open at an end of the partition wall lies flush with an end face of a bulge. Even when the bolt hole is positioned behind the bulge, the bolt inlet can be seen, and the bolt can be inserted from the bolt inlet into the partition wall. If the partition wall has an inner wall of a tapered shape progressively smaller in diameter toward the bolt hole, then the bolt can easily be inserted along the inner wall of the partition wall into the bolt hole.