| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a needle valve capable of being shut completely, eliminating galling, and pulling the valve stem away with a minor force. <P>SOLUTION: An annular piezo element (a ring) 4A is installed in an aperture 2b opened over a passage 2. Upon driving the valve stem 1 to the end, the voltage impressed condition on the ring 4A is turned on, and the ring 4A is allowed to make a contracting motion. This causes the inside diameter of the ring 4A to reduce, and the inner peripheral surface 4a of the ring 4A is put in tight contact with the whole periphery of the distal end part 1a of the valve stem 1, and thus the valve is shut completely. When the passage 2 is to be opened in this condition, the voltage impressed condition on the ring 4A is turned off, and the ring 4A is allowed to make an elongating motion. This causes the inside diameter of the ring 4A to increase, and the inside surface 4a of the ring 4A separates from the whole periphery of the distal end part 1a of the valve stem 1, which will eliminate galling of the valve. <P>COPYRIGHT: (C)2013,JPO&INPIT |
