Patent ID: 7665510

Claim:
A fluid drive unit for vibrating fluid charged in a passage in a direction of the passage, comprising: a moving piece accommodating portion communicating with both end portions of the passage, a moving piece slidably accommodated in the moving piece accommodating portion, the fluid in the passage being accommodated in spaces interposed between both end portions of the moving piece accommodating portion in the sliding direction of the moving piece and the end portions of the passage; and drive means for reciprocating the moving piece in the moving piece accommodating portion in the sliding direction, wherein the fluid charged in the passage is vibrated in the passage direction when the moving piece is reciprocated by the drive means; the moving piece includes temporary magnets arranged at both end portions in the sliding direction, and a permanent magnet is arranged between the temporary magnets arranged at both end portions, and the moving piece includes a cylindrical body for accommodating the permanent magnet, the permanent magnet is accommodated in the cylindrical body, and the temporary magnets are arranged opposed to each other at both end portions of the permanent magnet in the sliding direction of the moving piece, the moving piece comprises a sliding piece provided with a sliding face sliding against the moving accommodation portion, on an outer surface of the sliding piece opposed to the moving piece accommodation portion of the cylindrical body, the drive means reciprocates the moving piece by magnetic force; a groove is formed on a surface of the moving piece from both end portions of the moving piece in the sliding direction to a central portion; and the groove formed on the surface of the moving piece is a spiral groove turning on the side of the moving piece in the sliding direction.