Pumps – Condition responsive control of pump drive motor – Having timer or delay means
Reexamination Certificate
2000-07-24
2002-06-04
Freay, Charles G. (Department: 3746)
Pumps
Condition responsive control of pump drive motor
Having timer or delay means
C417S044100
Reexamination Certificate
active
06398506
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a centrifugal fluid pump assembly for pumping a medical fluid, typically blood.
In recent medical treatment, centrifugal blood pumps are increasingly used in artificial heart/lung units for extracolporeal blood circulation. Centrifugal pumps of the magnetic coupling type wherein a driving torque from an external motor is transmitted to an impeller through magnetic coupling are commonly used because the physical communication between the blood chamber of the pump and the exterior can be completely excluded to prevent invasion of bacteria.
The centrifugal blood pump includes a housing having a blood inlet port and a blood outlet port and an impeller rotatable accommodated in the housing and feeding blood by a centrifugal force generated during its rotation. The impeller is having magnetic materials (permanent magnet) disposed therein is rotated by a rotor having magnets for attracting the magnetic materials of the impeller thereto and by a rotational torque generating mechanism having a motor for rotating the rotor. The impeller rotates without contacting the housing, with the impeller being attracted to the side opposite to the rotor-disposed side by a magnetic force.
In the magnet coupling-utilizing centrifugal fluid pump, there is a danger that the magnet coupling may have a power saving (in other words, decoupling between the impeller and the rotor) when a load is excessively increasingly applied to the rotating impeller and the like. when the power swing occurs, the rotation of the impeller stops.
The use of a magnet having a large magnetic force is conceivable to prevent the power swing from occurring in the magnet coupling. The impeller is capable of rotating without contacting the housing generate owing to the balance between the attractive force generated by the magnet coupling between the impeller and the rotor and an attractive force, reciprocal to the attractive force of the magnet coupling, generated by an electromagnet or the like. It is possible to prevent the occurrence of the power swing by increasing the magnetic force in the magnet coupling. But it is necessary to provide the electromagnet with high current. However, the reduction of the power consumption is an important subject in the blood pump to be implanted in the human body.
It is a first object of the invention to provide a centrifugal fluid pump assembly capable of preventing power swing from occurring in magnet coupling, namely, between an impeller and a rotor without increasing the magnetic force in the magnet coupling.
In the magnet coupling-utilizing centrifugal fluid pump, there is a danger that the magnet coupling may have a power swing when a load is excessively increasingly applied to the rotating impeller and the like. when the power swing occurs, the rotation of the impeller stops. Therefore, it is desirable to reliably grasp the occurrence of the power swing in the magnet coupling. It is also desirable for a determining function to erroneously determine a state in which the power swing has not occurred as a state in which the power swing has occurred.
It is a second object of the invention to provide a centrifugal fluid pump assembly having a power swing detection function which allows whether or not the power swing has occurred in the magnet coupling to be checked securely from outside and which rarely erroneously determines a state in which the power swing has not occurred as a state in which the power saving has occurred.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a centrifugal fluid pump assembly comprises a centrifugal fluid pump comprising a centrifugal fluid pump section including a housing having a blood inlet port and a blood outlet port and an impeller having a first magnetic material and a second magnetic material disposed thereof and accommodated for rotation in the housing and without contacting the housing to feed a fluid by a centrifugal force developed during its rotation, an impeller rotational torque generating section including a rotor having a magnet for attracting the first magnetic material of the impeller and a motor for rotating the rotor, and an impeller position control section having an electromagnet for attracting the second magnetic material of the impeller, and a control device having an input portion for inputting a set number of rotations of the motor or an input portion for inputting a set motor-driving current value; and a function of limiting an input of a number of rotations of the motor more than a predetermined number of rotations or limiting an input of the motor-driving current having a value more than a predetermined value.
According to a second aspect of the invention, there is provided a centrifugal fluid plump assembly comprises a centrifugal fluid pump comprising a centrifugal fluid pump section including a housing having a blood inlet port and a blood outlet port and an impeller having a first magnetic material and a second magnetic material disposed thereof and accommodated for rotation in the housing and without contacting the housing to feed a fluid by a centrifugal force developed during its rotation, an impeller rotational torque generating section including a rotor having a magnet for attracting the first magnetic material of the impeller and a motor for rotating the rotor, and an impeller position control section having an electromagnet for attracting the second magnetic material of the impeller, and a control device having an input portion for inputting a motor-driving current value or an input portion for inputting a set number-of-rotations of the motor; and a motor rotation control part having a function of storing an upper limit value of the motor-driving current and a function of limiting a supply of the motor-driving current having a value more than the stored upper limit value to the motor.
According to a third aspect of the invention, there is provided a centrifugal fluid pump assembly comprises a centrifugal fluid pump comprising a centrifugal fluid pump section inducing a housing having a blood inlet port and a blood outlet port and an impeller having a first magnetic material and a second magnetic material disposed thereof and accommodated for rotation in the housing and without contacting the housing to feed a fluid by a centrifugal force developed during its rotation, an impeller rotational torque generating section including a rotor having a magnet for attracting the first magnetic material of the impeller and a motor for rotating the rotor, and an impeller position control section having an electromagnet for attracting the second magnetic material of the impeller, and a control device including an input portion for inputting a set number of rotations of the motor and a motor rotation control part having a function of storing an upper limit of the number of rotations of the motor; a comparing function of comparing the stored upper limit of the number of rotations of the motor, with a set number of rotations of the motor inputted at the input portion for inputting a set number of rotations of the motor; and a motor rotation control function of controlling a rotation of the motor such that the motor rotates at the set number of rotations of the motor it the set number of rotations of the motor is smaller than the upper limit of the number of rotations of the motor and such that the motor rotates at the upper limit of the number of rotations of the motor if the set number of rotations of the motor is more than the upper limit value thereof.
According to a forth aspect of the invention, there is provided a centrifugal fluid pump assembly comprises a centrifugal fluid pump comprising a centrifugal fluid pump section including a housing having a blood inlet port and a blood outlet port and an impeller having a first magnetic material and a second magnetic material disposed thereof and accommodated for rotation in the housing and without contacting the housing to feed a fluid by a centrifugal force developed during its rotation, an im
Maekawa Jun
Ozaki Takayoshi
Burns Doane , Swecker, Mathis LLP
Freay Charles G.
Rodriguez William H.
Terumo Kabushiki Kaisha
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