In a linear motor, a can has a two-layer structure including an inner can 2 and an outer can 3, and an inner passage 7 formed between an armature winding 9 and the inner can 2 and an outer passage 8 formed between the inner can 2 and the outer can 3 are constituted by each can. Communicating portions 7A and 8A for causing the inner passage 7 and the outer passage 8 to communicate with each other are provided in the vicinity of a refrigerant supply port 5 in each of the cans 2 and 3 in such a manner that a refrigerant supplied from the refrigerant supply port 5 branches into the inner passage 7 and the outer passage 8 and thus flows. Consequently, it is possible to obtain a linear motor armature and a linear motor having a high cooling capability which can prevent the deformation of the can by using a conventional inactive refrigerant to improve the passage for the refrigerant.
In a moving magnet type linear actuator (10), a stator (30) having an armature (32) including a magnetic iron core (33) fixed on a stator base (31) and an armature winding (34) wound around the magnetic iron core (33); and a movable body (20) having a field permanent magnet (21) arranged oppositely to the magnetic iron core (33) through a magnetic gap and a magnetic holder (22) supporting the field permanent magnet (21) and movably arranged on the stator base (31), the magnetic holder (22) is made of a non-magnetic substance, and a magnetic back yoke (39) is arranged on the side opposite to the armature with respect to the field permanent magnet (22) to from a gap between the magnetic back yoke (39) and the field permanent magnet (21) and is fixed to supporters provided on the stator base (31). In accordance with this configuration, there is provided a moving magnet type linear actuator which can reduce the weight of the movable body to improve the accelerating performance and gives no problem about the life of linear guides.
