Dual-action irrigation pump with variable speed to provide constant fluid flow

Abstract

A dual-action pump includes a cylinder, a piston and a controller. The cylinder includes first and second inlet-outlet ports, each of the first and second inlet-outlet ports is configured to alternately intake a fluid to the cylinder and output the fluid from the cylinder. The piston is configured to be moved within the cylinder in a periodic cycle that alternately reverses a direction of movement of the piston, so as to pump the fluid through the first and second inlet-outlet ports. The controller is configured to control the movement of the piston within the cylinder, including setting to the piston: (a) a first speed, during a first predefined interval that precedes reversing the direction of movement, (b) a second speed, larger than the first speed, during a second predefined interval that follows reversing the direction, and (c) a baseline speed, smaller than the first speed, outside the first and second intervals.

1 . An apparatus, comprising:
 (a) a cylinder extending longitudinally between first and second ends, the cylinder comprising:
 (i) a first inlet-outlet port including a first opening in the cylinder at the first end, the first inlet-outlet port being configured to alternately intake a fluid to the cylinder and output the fluid from the cylinder, and 
 (ii) a second inlet-outlet port including a second opening in the cylinder at the second end, the second inlet-outlet port being configured to alternately intake the fluid to the cylinder and output the fluid from the cylinder; 
   (b) a piston configured to move longitudinally within the cylinder for selectively pumping the fluid through each of the first and second inlet-outlet ports; and   (c) a controller operatively coupled to the piston, the controller being configured to:
 (i) actuate movement of the piston in a first direction toward the second end at a baseline speed, 
 (ii) accelerate the movement of the piston in the first direction from the baseline speed to a first increased speed greater than the baseline speed in response to the piston reaching a first predefined distance from the second end, 
 (iii) arrest the movement of the piston in the first direction in response to the piston reaching a second predefined distance from the second end, and 
 (iv) actuate movement of the piston in a second direction toward the first end at a second increased speed greater than the first increased speed after arresting the movement of the piston in the first direction. 
   
     
     
         2 . The apparatus according to  claim 1 , the controller being configured to decelerate the movement of the piston in the second direction from the second increased speed to the baseline speed in response to the piston reaching a third predefined distance from the second end. 
     
     
         3 . The apparatus according to  claim 2 , the first and third predefined distances being the same. 
     
     
         4 . The apparatus according to  claim 2 , the controller being configured to accelerate the movement of the piston in the second direction from the baseline speed to the first increased speed in response to the piston reaching a fourth predefined distance from the second end. 
     
     
         5 . The apparatus according to  claim 4 , the controller being configured to arrest the movement of the piston in the second direction in response to the piston reaching a fifth predefined distance from the second end. 
     
     
         6 . The apparatus according to  claim 5 , the controller being configured to actuate movement of the piston in the first direction at the second increased speed after arresting the movement of the piston in the second direction. 
     
     
         7 . The apparatus according to  claim 1 , further comprising a piston position sensor assembly (PPSA) configured to provide a control signal indicative of a longitudinal position of the piston within the cylinder, the controller being configured to receive the control signal from the piston position sensor assembly. 
     
     
         8 . The apparatus according to  claim 7 , the PPSA comprising at least one electrical switch. 
     
     
         9 . The apparatus according to  claim 1 , the controller being configured to control a predefined volume of the fluid to be pumped through the first and second inlet-outlet ports during a first time interval between commencing accelerating the movement of the piston in the first direction and completing actuating the movement of the piston in the second direction, and to control the same predefined volume of the fluid to be pumped through the first and second inlet-outlet ports during a second time interval in which the controller actuates the movement of the piston at the baseline speed, the second time interval being approximately equal to the first time interval. 
     
     
         10 . The apparatus according to  claim 1 , each of the first and second inlet-outlet ports being coupled to a fluid reservoir via a first conduit, and to a catheter via a second conduit, for irrigating tissue with the fluid during a medical procedure. 
     
     
         11 . The apparatus according to  claim 1 , wherein the controller is configured to maintain a constant flow rate of the fluid through the cylinder. 
     
     
         12 . The apparatus according to  claim 11 , wherein the controller is configured to set one or more of the baseline speed, the first increased speed, the second increased speed, the first predefined distance from the second end, or the second predefined distance from the second end in order to maintain the constant flow rate of the fluid through the cylinder. 
     
     
         13 . The apparatus according to  claim 7 , wherein the controller is configured to accelerate the movement of the piston in the first direction from the baseline speed to the first increased speed in response to a signal from the PPSA that the piston has reached the first predefined distance from the second end. 
     
     
         14 . The apparatus according to  claim 7 , wherein the controller is configured to arrest the movement of the piston in the first direction in response to a signal from the PPSA that the piston has reached the second predefined distance from the second end. 
     
     
         15 . The apparatus according to  claim 7 , wherein the controller is configured to actuate the movement of the piston in the second direction toward the first end at the second increased speed after arresting the movement of the piston in the first direction in response to a signal from the PPSA that the piston has reached the second predefined distance from the second end. 
     
     
         16 . The apparatus according to  claim 1 , wherein the first predefined distance from the second end and the second predefined distance from the second end are the same. 
     
     
         17 . The apparatus according to  claim 1 , wherein the first predefined distance from the second end and the second predefined distance from the second end are different from each other. 
     
     
         18 . The apparatus according to  claim 12 , wherein the controller is configured to set the first predefined distance from the second end and the second predefined distance from the second end to be the same. 
     
     
         19 . The apparatus according to  claim 12 , wherein the controller is configured to set the first predefined distance from the second end and the second predefined distance from the second end to be different from each other.