Patent ID: 6840735

Claim:
A centrifugal fluid pump apparatus comprising a pump body in which an impeller rotates without contacting a housing; and control means for controlling said pump body, said pump body comprising: said housing having a blood inlet port and a blood outlet port; a centrifugal pump section including an impeller having a first magnetic material and a second magnetic material and rotating in said housing to feed a fluid by a centrifugal force generated during its rotation; an impeller rotational torque generation section including a rotor having a magnet for attracting said first magnetic material of said impeller and a motor for rotating said rotor; an impeller position control section having an electromagnet for attracting said second magnetic material of said impeller; a position sensor for detecting a position of said impeller; and a groove for hydrodynamic bearing provided on an inner surface of said housing at a side of said rotor or on a surface of said impeller at a side of said rotor, said control means: monitoring at least one of an output of the position sensor and a current of the electromagnet; monitoring a motor current; determining at least one of a failure of the sensor or a failure of the electromagnet by using said monitoring of at least one of the output of the position sensor and the current of the electromagnet; and operating in an emergency impeller rotation control mode upon detection of the failure of the sensor or the failure of the electromagnet to rotate said impeller by utilizing said groove for hydrodynamic bearing without substantial contact between said impeller and said housing, said control means: stopping said electromagnet from attracting said impeller upon detection of said failure and gradually decreasing a motor speed to thereby execute magnetic coupling between said impeller and said rotor; detecting magnetic re-coupling between said impeller and said rotor by using the motor current monitored by said control means; and increasing the motor speed up to a predetermined value after detection of said magnetic re-coupling.