Patent ID: 6146070
Filing Date: 2000-11-14
Classification: F16B,Y10S

Abstract:
A bolt/nut unfastening preventing structure, comprising:a bolt (3) having its shank portion (4) pass through through-holes (2) of assembled members (1);a fastening nut (5) threadably fitted to said bolt (3) to fasten said assembled members (1) between said bolt and fastening nut;a stopper nut (6) fitted to said bolt (3) after said assembled members (1) are fastened between said fastening nut (5) and said bolt (3), said stopper nut (6) being disposed adjacent to said fastening nut (5) and in press-contact with said fastening nut (5) to prevent said fastening nut (5) from loosening relative to said bolt (3);said stopper nut (6) being constructed of a main body portion (6a) and a driven portion (6b), wherein said main body portion (6a) of said stopper nut (6) is loosely received in an opening end portion (7a) of a cylindrical cover element (7) so as to be capable of freely rotatable relative to said opening end portion (7a) of said cover element (7), and is fastened tight to said fastening nut (5), wherein said driven portion (6b) of said stopper nut (6) is not fitted to said shank portion (4) of said bolt (3), but is fitted to a driving portion (7b) of said cylindrical cover element (7) so as to rotate together with said cylindrical cover member (7), said driving portion (7b) constituting the innermost portion of said cylindrical cover element (7);and wherein said stopper nut (6) is further provided with a weak portion (6c) between said main body portion (6a) and said driven portion (6b), said weak portion (6c) being determined in mechanical strength so as to be broken when a predetermined torque is applied to said cylindrical cover element (7) so as to have said main body portion (6a) of said stopper nut (6) fastened tight to said fastening nut (5).