| abstract |
A tightly closed casing (1) has an inside space (1a) for storing coolantngas. A block (6) is accommodated in this casing. A motor (3) includes a statorn(3a) and a mover (3b). A piston (5) is connected to the mover (3b) of thenmotor. A movable element (12) includes the mover (3b) of the motor and thenpiston (5). A stationary element (13) includes the stator (3a) of the motor andnthe block (6). An elastic element (8) has a portion (8b) fixed to the movablenelement (12) and another portion (8c) fixed to the stationary element (13). Ancylinder (4) is shiftable in an axial direction with respect the block (6). Anshifting device (16) shifts the cylinder (4) in the axial direction. |