Patent ID: 7349293

Claim:
A pressure control apparatus comprising: a columnar magnetostrictive element section disposed between respective one ends of a first rotating rod and a second rotating rod, wherein the first rotating rod and the second rotating rod are arranged on the same axis such that the one ends thereof are opposed to each other, the first rotating rod and the second rotating rod being connected to each other such that the opposed one ends are unrotatable relative to each other but at the same time are movable toward and away from each other along the axis, the first rotating rod and the second rotating rod being capable of rotating about the axis in unison with each other in a state where the other ends thereof are restricted in movement along a direction of the axis; urging means for always urging the first rotating rod and the second rotating rod to cause them to be closer to each other to thereby bring the respective one ends of the rotating rods into intimate contact with respective ends of said magnetostrictive element section, respectively; magnetic field-applying means for generating a magnetic field for use in adjusting a length of said magnetostrictive element section along the direction of the axis, to apply the magnetic field to said magnetostrictive element section; pressure-detecting means for detecting pressure generated in the first rotating rod and the second rotating rod in the direction of the axis; and a control section for controlling the pressure detected by said pressure-detecting means such that the pressure is constant, by controlling a strength of the magnetic field applied by said magnetic field-applying means to adjust the length of said magnetostrictive element section.