Positive displacement pump system and method

Abstract

Systems and methods including a motor or electromagnets to control the movement of one or more pistons in a pumping chamber. The pumping chamber may include a pump inlet and a pump outlet in fluid communication with the pumping chamber. Surfaces on a piston or pumping chamber may include hydrodynamic bearing surfaces.

1 . A system comprising: 
 a pumping chamber forming a loop;    a pump inlet in fluid communication with the pumping chamber;    a pump outlet in fluid communication with the pumping chamber;    a first piston disposed within the pumping chamber;    a second piston disposed within the pumping chamber;    an electric motor; and    an electromagnet, wherein the system is configured such that during operation: 
 the electromagnet is initially coupled to the first piston;  
 the electric motor is initially coupled to the second piston;  
 the electromagnet is subsequently coupled to the second piston; and  
 the electric motor is subsequently coupled to the first piston.  
   
   
   
       2 . The system of  claim 1  wherein the system is configured such that during operation: 
 the electromagnet is coupled to either the first or second piston when the electromagnet is energized; and    the electromagnet is not coupled to either the first or second piston when the electromagnet is de-energized.    
   
   
       3 . The system of  claim 1 , further comprising a magnetic ring, wherein the system is configured such that during operation: 
 the electric motor exerts a first magnetic force on the first piston;    the magnetic ring exerts a second magnetic force on the first piston; and    the first magnetic force opposes the second magnetic force.    
   
   
       4 . The system of  claim 3  wherein the magnetic ring comprises a permanent magnet or Halbach array.  
   
   
       5 . The system of  claim 1 , wherein the system is configured such that during operation: 
 the motor comprises a rotor with a magnetic link;    the magnetic link is initially coupled to the second piston and subsequently coupled to the first piston.    
   
   
       6 . The system of  claim 5 , wherein the magnetic link comprises a permanent magnet or Halbach array.  
   
   
       7 . The system of  claim 5 , wherein the system is configured such that during operation: 
 a portion of the magnetic link extends beyond a leading face of the piston.    
   
   
       8 . The system of  claim 1 , wherein the first piston and the second piston each comprise a permanent magnet or Halbach array.  
   
   
       9 . The system of  claim 1  wherein the system is configured such that during operation: 
 the pump inlet is inserted into a ventricle;    the pump outlet is in fluid communication with the ascending aorta, the descending aorta, or a pulmonary artery.    
   
   
       10 . The system of  claim 1  wherein the system is configured such that: 
 the motor comprises a rotor coupled to a linking arm;    the linking arm is coupled to a first magnet, wherein the first magnet is located on a first side of the piston during operation;    the linking arm is coupled to a second magnet, wherein the second magnet is located on a second side of the piston during operation; and    the first side is opposed to the second side.    
   
   
       11 . The system of  claim 1  wherein the first piston or the second piston comprise a hydrodynamic bearing surface.  
   
   
       12 . A method of pumping a fluid, the method comprising: 
 providing a pumping chamber, wherein the pumping chamber contains the fluid;    providing a pump inlet in fluid communication with the pumping chamber;    providing a pump outlet in fluid communication with the pumping chamber;    providing a first piston disposed within the pumping chamber;    providing a second piston disposed within the pumping chamber;    providing an electric motor comprising a rotor;    providing an electromagnet;    coupling the electromagnet to the first piston;    coupling the rotor to the second piston;    holding the first piston in a first location with the electromagnet;    rotating the rotor and moving the second piston closer to the first piston so that a portion of the fluid is forced out of the pump outlet;    de-energizing the electromagnet and uncoupling the electromagnet from the first piston;    energizing the electromagnet so that it couples to the second piston; and    coupling the rotor to the first piston.    
   
   
       13 . The method of  claim 12 , further comprising: 
 rotating the rotor and moving the first piston closer to the second piston so that a portion of the fluid is forced out of the pump outlet.    
   
   
       14 . The method of  claim 11  wherein the first location is between the pump inlet and the pump outlet.  
   
   
       15 . A system comprising: 
 a pumping chamber comprising an inner surface forming a loop;    a pump inlet in fluid communication with the pumping chamber;    a pump outlet in fluid communication with the pumping chamber;    a piston disposed within the pumping chamber; and    a first electric motor magnetically coupled to the piston, wherein: 
 the piston comprises a hydrodynamic bearing surface configured to repel the piston away from the inner surface as the piston moves within the pumping chamber.  
   
   
   
       16 . The system of  claim 15 , wherein: 
 the loop is centered about a central axis;    the piston comprises an upper surface, a lower surface, an inner surface, an outer surface, a leading face, and a trailing face; and    the inner surface comprises an upper wall, a lower wall, an inner wall and an outer wall.    
   
   
       17 . The system of  claim 16 , wherein during operation: 
 a first lower gap exists between the lower surface and the lower wall proximal to the leading face;    a second lower gap exists between the lower surface and the lower wall proximal to the trailing face;    the first lower gap is larger than the second lower gap;    a first upper gap exists between the upper surface and the upper wall proximal to the leading face;    a second upper gap exists between the upper surface and the upper wall proximal to the trailing face; and    the first upper gap is larger than the second upper gap.    
   
   
       18 . The system of  claim 16 , wherein a portion of the lower surface is not perpendicular to the central axis and a portion of the upper surface is not perpendicular to the central axis.  
   
   
       19 . The system of  claim 16 , wherein: 
 a first outer gap exists between the outer surface and the outer wall proximal to the leading face;    a second outer gap exists between the outer surface and the outer wall proximal to the trailing face; and    the first outer gap is larger than the second outer gap.    
   
   
       20 . The system of  claim 15  further comprising a pinch valve between the pump inlet and the pump outlet.  
   
   
       21 . The system of  claim 15  further comprising: 
 a second piston disposed within the pumping chamber;    a second electric motor coupled to the second piston, wherein:    the second piston comprises a hydrodynamic bearing surface configured to repel the second piston away from the inner surface as the second piston moves within the pumping chamber.    
   
   
       22 . The system of  claim 15 , further comprising: 
 a power supply;    a driver circuit electrically coupled to the electric motor and the power supply;    a microprocessor electrically coupled to the driver circuit; and    a sensor for sensing a position of the piston within the pumping chamber, wherein: 
 the driver circuit is configured to selectively couple the power supply to the electric motor upon receiving a control signal;  
 the sensor is electrically connected to the microprocessor;  
 the microprocessor is configured to interpret the position from the sensor; and  
 the microprocessor is configured to output the control signal to the driver circuit.  
   
   
   
       23 . The system of  claim 15  wherein a position and a velocity of the piston are controlled to produce a predetermined waveform in an outlet flow from the pump outlet.  
   
   
       24 . The system of  claim 15  further comprising a fluid within the pumping chamber and a sensor configured to measure a property of the fluid.  
   
   
       25 . The system of  claim 15 , wherein the piston or inner surface comprise one or more of the following: a nanoparticulate surface, a microporous coating, or a fibrous flocking configured to facilitate endothelial or pseudoneointimal protein or cell aggregation.  
   
   
       26 . The system of  claim 15 , further comprising: 
 a pacemaker; and    a microprocessor, wherein 
 the pacemaker comprises one or more electrodes electrically coupled to a heart;  
 the pacemaker is electrically coupled to the microprocessor;  
 the pacemaker provides a depolarization output to the one or more electrodes;  
 the heart is controlled to contract at a predetermined time relative to an actuation stroke of the pump.  
   
   
   
       27 . The system of  claim 15  further comprising a sensor, wherein: 
 the sensor is configured to sense a physiological parameter;    the system is configured to increase or decrease a volumetric flow rate from the pumping chamber based on the physiological parameter.    
   
   
       28 . The system of  claim 27  wherein the sensor comprises one or more electrodes for measuring thoracic impedance, p-wave activity, renal sympathetic nerve activity, or aortic nerve activity.  
   
   
       29 . The system of  claim 27  wherein the sensor comprises an accelerometer for sensing a heart contraction, a diaphragm motion, a bodily inclination, or a walking pace.  
   
   
       30 . A pump for circulating fluid comprising: 
 a pumping chamber;    a pump inlet in fluid communication with the pumping chamber;    a pump outlet in fluid communication with the pumping chamber;    a drive piston disposed within the pumping chamber; and    a hollow valve sleeve configured to recess into the pump outlet.    
   
   
       31 . A system comprising: 
 a pumping chamber forming a loop;    a pump inlet in fluid communication with the pumping chamber;    a pump outlet in fluid communication with the pumping chamber;    a piston disposed within the pumping chamber;    an electric motor comprising a rotor coupled to a shaft;    a magnet coupled to an end of the shaft;    a sensor proximal to the magnet; and    a control system, wherein: 
 the electric motor is magnetically coupled to the piston;  
 the magnet produces a magnetic vector that rotates with the rotor;  
 the sensor is configured sense the magnetic vector; and  
 the control system is configured to determine the angular position of the rotor.  
   
   
   
       32 . The system of  claim 31 , wherein the sensor is a  2 -axis Hall effect sensor.  
   
   
       33 . The system of  claim 31 , wherein the electric motor is an axial flux motor.  
   
   
       34 . The system of  claim 31 , wherein the control system is configured to access a lookup table.  
   
   
       35 . A system comprising: 
 a pumping chamber comprising an inner surface forming a loop;    a pump inlet in fluid communication with the pumping chamber;    a pump outlet in fluid communication with the pumping chamber;    a first piston disposed within the pumping chamber; and    a series of electromagnets disposed around the pumping chamber, wherein: 
 the series of electromagnets are configured to move the first piston around the pumping chamber; and  
 the first piston comprises a hydrodynamic bearing surface configured to repel the first piston away from the inner surface as the first piston moves within the pumping chamber.  
   
   
   
       36 . The system of  claim 35  further comprising a second piston disposed within the pumping chamber, wherein: 
 the series of electromagnets are configured to move the second piston around the pumping chamber; and    the second piston comprises a hydrodynamic bearing surface configured to repel the second piston away from the inner surface as the second piston moves within the pumping chamber.    
   
   
       37 . The system of  claim 35  further comprising a pinch valve between the pump inlet and pump outlet.