Magnet arrangement, and drive device and cooling apparatus incorporating same

摘要

PCT No. PCT/GB93/02245 Sec. 371 Date Apr. 12, 1995 Sec. 102(e) Date Apr. 12, 1995 PCT Filed Nov. 1, 1993 PCT Pub. No. WO94/10741 PCT Pub. Date May 11, 1994A linear motor (220) suitable for use with a cryogenic cooler is described. The arrangement comprises first and second annular magnets (100 and 110), which in the preferred embodiment are nested and share a common axis. A circular bore (190) is defined about the common axis and is able to receive a drive shaft (220). The drive shaft (220) is connected to a base member (210) which has an annular peripheral region (200) in which a coil (200) is defined. Coil (200) has poles (150 and 160). The coil (200) when energised causes reciprocal motion of the drive shaft (220). The coil (200) per se is able to move into and out of an annular cavity (170) defined between the nested magnets (100 and 110).