Solenoid operated blood pump drive system

Abstract

A solenoid operated drive system or actuating unit for driving blood pumps such as intra-arterial 'balloon' pumps, implantable pulsatile pumps, external pumps and the like, wherein a shaft attached to the movable end of a bellows is caused to move back and forth by a pair of oppositely disposed solenoids. The extent of the excursion of the shaft and hence the movable end of the bellows is variably controlled by a first stopper fixedly attached to the frame and a second stopper fixedly attached to a carriage which is adjustably carried within the frame. The solenoids are alternately actuated and/or controlled by suitable control signals which are keyed to the heartbeat or R wave. At the beginning of each cycle for each solenoid and for a short time thereafter, depending on the cycle, a voltage is applied to provide maximum drive. At the end of the maximum drive portion, a reduced voltage is applied to provide a drive and/or holding force of lesser magnitude and is maintained until after the shaft has stopped moving. Thereafter, the reduced voltage is removed and/or current flow through the solenoid is prevented for a further period of time until the next cycle for this solenoid begins with the application of the high voltage. Adjustable noise reducing bumpers are provided to keep impact noises at a minimum and insure the maintenance of a fixed stopping point over extended periods of time.