| 摘要 |
PROBLEM TO BE SOLVED: To reduce impact that could be received at the time of valve seating by structuring the valve drive device with a drive means that contains a magnetic path member composed of a magnetic flux generating part by means of an electromagnetic coil and a magnetic field forming part equipped with two pole pieces that form one magnetic field, and a magnetic path member; a polarizing member that corresponds to the magnetic field zone and that is equipped with two different polarization surfaces and interlocked with the valve stem integrated with the valve body. SOLUTION: When, for example, a dc current in a predetermined direction is supplied to an electromagnetic coil 38, polarizing members 21, 22 move in the direction of an arrow A together with a valve stem 12 in proportion to the magnitude of a flux density formed in a core 37 so that S poles are generated in pole pieces 34, 36 and an N pole is generated in a pole piece 35 to form a magnetic path that goes around the following parts: N pole of the polarizing member 21→pole piece 34→yoke 31→magnetic gap 39→core 37→pole piece 35→pole S of the polarizing member 22→N pole of the polarizing member 22→yoke 32→S pole of the polarizing member 21. When a dc current in the opposite direction is supplied to the electromagnetic coil 38, the polarizing members 21, 22 move in the direction of an arrow B together with the valve stem 12 so that a circulating magnetic field is formed with N poles generated in the pole pieces 34, 36 and an S pole in the pole piece 35.
|
