Rotary cam actuated linear peristaltic pump

Abstract

A rotary cam actuated linear peristaltic pump includes a plurality of cams which actuate a plurality of pistons. The cams apply a force to the piston by way of a lifter for providing mechanical advantage so that a smaller motor may be used to rotate the cam. Each piston of a plurality of pistons is sequentially raised to the extended position to squeeze a tube so as to flow fluid through the tube.

1 . A peristaltic pump for flowing fluid through a lumen of a tube, the tube defining a diameter, the pump comprising:
 a plurality of pistons linearly arranged adjacent to each other in a straight configuration, each of the plurality of pistons defining opposed first and second ends, each of the plurality of pistons traversable between extended and retracted positions;   a plurality of lifters, each lifter being pivotable about a pivot axis;   a platen disposed adjacent to the first ends of the plurality of pistons, the platen generally parallel to the plurality of pistons wherein a gap between the first end of one of the plurality of pistons and the platen is about equal to or more than a diameter of the tube when the piston is traversed to the retracted position and the gap is smaller than the diameter of the tube when the piston is traversed to the extended position;   a rotatable cam shaft generally parallel to the plurality of pistons;   a plurality of cams mounted to the rotatable cam shaft, each of the cams having a cam lobe, the cam lobes of the plurality of cams disposable adjacent to second end portions of the lifters with the second ends of the pistons positioned in between the second end portions of the lifters and the pivot axis of the lifters so that as the cam shaft rotates, the lobes raise the lifters which provide a mechanical advantage to traverse the pistons to the extended position, the plurality of cams are angularly displaced with respect to the adjacent cam, the plurality of pistons being sequentially traversed to the extended position to flow fluid through the tube.   
     
     
         2 . The pump of  claim 1  wherein the platen is traverseable between an open position for inserting or removing the tube between the plurality of pistons and the platen and a closed position for flowing fluid through the lumen of the tube when the tube is disposed between the platen and the plurality of pistons. 
     
     
         3 . The pump of  claim 1  further comprising:
 a worm gear attached to the cam shaft; 
 a worm drive engaged to the worm gear; 
 a motor attached to the worm drive for rotating the worm drive. 
 
     
     
         4 . The pump of  claim 1  wherein the plurality of pistons linearly occludes the tube as each one of the plurality of pistons is sequentially traversed to the extended position due to the progressive angular displacement of the cams. 
     
     
         5 . The pump of  claim 1  wherein each of the cams has four lobes spaced 90 degrees apart from each other, and a total angular displacement of the plurality of cam is about 90 degrees. 
     
     
         6 . The pump of  claim 1  wherein the cam lobes of the cams have a curved peak surface defined by an arc having a center about a rotating axis of the cam shaft and the cams, the curved peak surface of cam lobes of adjacent cams offset and overlapping one another to urge fluid through the tube in one direction. 
     
     
         7 . The pump of  claim 1  wherein the pistons reciprocate between extended and retracted positions about a common axis, and the common axis of the reciprocating pistons, a flat surface of the platen and a rotating axis of the cam shaft are parallel with each other. 
     
     
         8 . A peristaltic pump for flowing fluid through a lumen of a tube, the tube defining a diameter, the pump comprising:
 a plurality of pistons linearly arranged adjacent to each other in a straight configuration, each of the plurality of pistons defining opposed first and second ends, each of the plurality of pistons traversable between extended and retracted positions;   a platen disposed adjacent to the first ends of the plurality of pistons, the platen generally parallel to the plurality of pistons wherein a gap between the first end of one of the plurality of pistons and the platen is about equal to or more than a diameter of the tube when the piston is traversed to the retracted position and the gap is smaller than the diameter of the tube when the piston is traversed to the extended position;   a rotatable cam shaft disposed adjacent to the second ends of the plurality of pistons, the rotatable cam shaft generally parallel to the plurality of pistons;   a plurality of cams mounted to the rotatable cam shaft, each of the cams having a cam lobe, the cam lobes of the plurality of cams disposable adjacent to the second ends of the plurality of pistons so that as the cam shaft rotates to traverse the piston to the extended position, the plurality of cams are angularly displaced with respect to the adjacent cam and the plurality of pistons are traversed to the extended position sequentially to flow fluid through the tube.   
     
     
         9 . The pump of  claim 8  wherein the platen defines a flat surface and the tube is squeezed between the plurality of pistons and the flat surface in a wave format to flow fluid through the tube, the flat surface being generally parallel to the plurality of pistons. 
     
     
         10 . A method of operating a peristaltic pump for flowing fluid through a lumen of a tube, the method comprising the steps of:
 disposing the tube between a platen and a plurality of pistons wherein the tube is straight and parallel to the platen and the plurality of pistons;   sequentially traversing the plurality of pistons to an extended position;   occluding the tube linearly down the tube when the pistons are sequentially traversed to the extended position;   pushing the piston back to a retracted position due to resiliency of the tube.   
     
     
         11 . The method of  claim 10  wherein the disposing step further includes the step of traversing the platen from an open position to a closed position. 
     
     
         12 . The method of  claim 10  further comprising the step of aligning the tube to be parallel to the platen and a cam shaft. 
     
     
         13 . The method of  claim 10  further comprising the step of rotating a cam shaft on which a plurality of cam are mounted, each of the cams having a cam lobe angularly offset from cam lobes of adjacent cams. 
     
     
         14 . The method of  claim 10  further comprising the step of actuating a plurality of lifters to sequentially traverse the plurality of pistons to the extended position.