| 摘要 |
<p>[Problem] To provide a piezoelectric actuator capable of preventing fatigue breakdown occurring at a welded portion due to tension stress and also provide a mass flow controller equipped with the piezoelectric actuator. [Solution] A piezoelectric actuator of the present invention comprises: a piezoelectric element (1); a base substance (2), the upper surface of which is attached to the lower end portion of the piezoelectric element (1); and a case (3) housing the piezoelectric element (1) therein and having an inner surface attached to the upper end portion of the piezoelectric element (1). In the piezoelectric actuator, the upper surface of the base substance (2) and the case (3) are joined with each other through a welded portion (4). The case (3) includes: a cylindrical portion (31) having a plurality of grooves (311) provided in a circumference direction; a curved portion (32) curving from the lower end of the cylindrical portion (31) and extending outward; and a flange portion (33) further extending outward from the curved portion (32). The thickness of the cylindrical portion (31) in at least one groove in the circumference direction from among the grooves (311) in the circumference direction is thinner than the thicknesses of the curved portion (32) and the flange portion (33).</p> |
