| 摘要 |
<p>A pivot rod, such as a push rod of the type found included in fuel injector drive trains and engine cylinder valve drive trains, has a mounting shaft (30) with an interior receiving space (33) at at least one end thereof, and a pivot insert (29b) formed of a ceramic material that is positioned with a first portion (37) thereof disposed within the receiving space (33) of the mounting shaft (30) and a second portion (43) thereof projecting axially beyond the end of the mounting shaft (30). To avoid tensile "hoop" stresses from exceeding the maximum tensile principle stress of the ceramic material of the pivot insert, despite the use of an interference fit securement between the pivot insert and the mounting shaft, and despite variations in the degree of diametral interference existing between the internal diameter (Di) of the receiving space (33) and the external diameter (Do) of the inserted pivot (29b) insert portion resulting from manufacturing tolerances, the wall (31) of the pivot shaft (30) taking part in the interference fit securement has its thickness (t) and material composition coordinated with the maximum tensile principle stress so that the wall (31) is plastically deformed by the pivot insert (29b) during formation of the interference fit securement. When an axially projecting portion (43) of the pivot insert has an abutment surface (47) in abutting engagement upon an end surface (45) of the mounting shaft, the axial length of the interference fit securement between the pivot insert and mounting shaft is also coordinated to the maximum tensile principle stress of the ceramic material.</p> |
