| 摘要 |
PROBLEM TO BE SOLVED: To provide an electrical steering system capable of avoiding biting of flank faces of screw threads mutually screwing between a feed screw and a nut even if temperature changes, and suppressing a variation of friction torque between the feed screw and the nut within a small range. SOLUTION: The feed screw 71 is so provided that the flank face 712C connecting a top 712A with a bottom 712B of the thread 712 of the feed screw 71 is protrudingly formed. The nut 73 is so provided that the flank face 731C connecting a top 731A with a bottom 731B of the thread 731 of the nut 73 is flatly formed. Accordingly, because a contact between the flank face 712C of the feed screw 71 and the flank face 731C of the nut 73 forms a line contact, a space 76 is formed between the flank face 712C and the flank face 731C. Thus, despite a thermal deformation of the flank face 712C and the flank face 731C due to the temperature changes, the space 76 can absorb the thermal deformation of the flank face 712C and the flank face 731C. COPYRIGHT: (C)2007,JPO&INPIT |
