Patent ID: 8622689

Claim:
A rotor drive mechanism capable of causing an external screw type rotor of a uniaxial eccentric screw pump to rotate and carry out a revolution movement, the uniaxial eccentric screw pump being configured such that the external screw type rotor is attached to an inner hole of an internal screw type stator; and causing the external screw type rotor to be driven by a rotation speed control driving portion such that the external screw type rotor rotates and to be driven by a revolution speed control driving portion such that the external screw type rotor carries out the revolution movement, the rotor drive mechanism comprising: a rotation shaft configured to have a central axis at a certain position and be rotatably supported; and a revolution shaft configured to be supported so as to be able to revolve about a certain central position and rotate and to have one end portion coupled to the rotation shaft via a power transmission portion and the other end portion coupled to the external screw type rotor; wherein the rotation shaft is rotated by the rotation speed control driving portion, and the revolution shaft is revolved by the revolution speed control driving portion to carry out an eccentric rotational movement, the rotor drive mechanism further comprising a shaft sealing structure configured such that a gap between an outer peripheral portion of said other end portion of the revolution shaft which end portion is located on an external screw type rotor side and an inner peripheral portion of a casing in the pump is sealed, wherein: the shaft sealing structure includes a circular coupling portion having an insert hole through which the revolution shaft is rotatably inserted, a gap between an inner peripheral portion of the circular coupling portion and an outer peripheral portion of the revolution shaft is sealed by a sealing portion, and a gap between an outer peripheral portion of the circular coupling portion and the inner peripheral portion of the casing is sealed by a diaphragm; and the circular coupling portion is rotatably attached to the revolution shaft via a bearing.