Tubular linear motor

The utility model relates to a tubular permanent-magnet linear motor used in an oil well, which is composed of an upper joint, a casing, a permanent magnet, an armature coil, joints, etc. The utility model adopts an external magnet type structure, the fixed permanent magnet is arranged in the casing, and an armature is arranged in the permanent magnet. The armature coil is wound in an annular tooth slot in a hollow steel core tube, and well liquid lifted by an electric pump flows through the core tube to carry away heat in the coil. The inside and the outside of the armature adopt a soft sealing form that communicating holes are filled with balanced plastic plugs to balance the pressure difference between the inside and the outside of a balanced armature sealing layer. A columnar extension spring is used as an attaching body of an electric connecting wire, and an electrical wire communicated with the armature is fixed on the spring. The motor casing adopts a segmented structure, and a connecting joint of the two casing segments are used as a linear bearing to support the armature. The thickness of a liner tube of the armature is reduced, the volume ratio of the tubular linear motor is improved, the work efficiency of the motor is improved, and the heat dissipation conditions of the armature are improved. The utility model overcomes the deficiencies of poor bearing ability, low performance volume ratio and poor heat dissipation performance of the existing tubular linear motor.