Uniform flow displacement pump

Abstract

A displacement pump comprising a pump assembly and a cassette assembly. The pump assembly includes upper and lower housing portions that define a cavity, an arm disposed in the cavity, a roller attached to the distal end of the arm, and a motor attached to the proximal end of the arm for rotating the arm. The cassette assembly is removably disposed in the cavity and comprises upper and lower cassette housing portions that form an annular compression surface with a channel therein. A hollow compression tube having a flange extending along a length thereof is secured to the compression surface by the flange being engaged with the channel. As the motor rotates the roller arm, the roller presses the compression tube against the compression surface to create a moving occlusion of the compression tube for pushing fluid through the compression tube.

What is claimed is:  
     
         1 - 13 . (canceled) 
     
     
         14 . A pump, comprising:
 a pump housing ( 20   a,    20   b ) that defines a cavity ( 26 ), the pump housing including a first pump housing portion ( 20   b ) and a second pump housing portion ( 20   a ), the pump housing portions ( 20   a,    20   b ) being engageable with one another to close the pump housing and being separable from one another to open the pump housing;   a compression surface ( 56 ) within the cavity ( 26 ) and having a channel ( 58 ) formed therein;   a hollow compression tube ( 60 ) secured to the compression surface ( 56 ), the hollow compression tube including a flange ( 62 ) extending along a length thereof, and the flange ( 62 ) being removably engaged with the channel ( 58 ) for securing the compression tube to the compression surface;   compression means ( 28 ,  29 ) within the cavity ( 26 ) for incrementally compressing the compression tube ( 60 ) against the compression surface ( 56 ) to create a moving occlusion of the compression tube that uniformly pushes fluid through the compression tube, wherein the compression means ( 28 ,  29 ) has at least one rest position in which the compression means does not compress the compression tube, the compression means including a roller ( 29 ) and means ( 28 ) for moving the roller ( 29 ) relative to the pump housing ( 20   a,    20   b ) when the pump housing is closed; and   a motor ( 30 ) disposed outside the cavity ( 26 ) and drivingly engaged with the moving means ( 28 ), characterised by   a cassette housing ( 46   a,    46   b ) disposed in the cavity ( 26 ) and containing the hollow compression tube ( 60 ), the cassette housing being shaped to define the compression surface ( 56 ) and the said channel ( 58 ) and to be removable together with the hollow compression tube ( 60 ) from the cavity ( 26 ) when the pump housing ( 20   a,    20   b ) is open while leaving the moving means ( 28 ) and the roller ( 29 ) remaining in the cavity ( 26 ), and in that the cassette housing has a lower cassette housing portion ( 46   b ) and an upper cassette housing portion ( 46   a ) removably attached to the lower cassette portion ( 46   b ) whereby the hollow compression tube ( 60 ) can be secured to and released from the cassette housing.   
     
     
         15 . The pump of  claim 14 , wherein the compression surface ( 56 ) is annularly shaped, and the moving means comprises a spring loaded arm ( 26 ) that rotates about a fixed point. 
     
     
         16 . The pump of  claim 14 , wherein the compression surface ( 56 ) is elliptically shaped; and the moving means comprises a spring loaded arm ( 28 ) that rotates about a fixed point. 
     
     
         17 . The pump of  claim 16 , wherein as the spring loaded arm ( 28 ) rotates through a complete revolution about the fixed point, the roller ( 29 ) disengages from the compression tube ( 60 ) at least twice. 
     
     
         18 . The pump of  claim 14 , wherein the compression means has a plurality of rollers that roll along the compression tube, and no more than one of the plurality of rollers compresses the compression tube at any given time. 
     
     
         19 . The pump of  claim 14 , wherein the flange ( 58 ) is tube shaped and integrally formed with the compression tube ( 60 ). 
     
     
         20 . The pump of claim  1 , wherein the compression means includes a second rest position in which the compression means forms a temporary pinch-valve by temporarily stalling the moving occlusion of the compression tube. 
     
     
         21 . The pump of  claim 14 , wherein the moving means includes an arm ( 28 ) having a proximal end and a distal end, wherein the roller ( 29 ) is attached to the distal end of the arm ( 28 ) and the motor ( 30 ) is drivingly engageable with the proximal end of the arm ( 28 ). 
     
     
         22 . The pump of  claim 21 , wherein the arm ( 28 ) is spring loaded for applying pressure on the compression tube ( 60 ) by the roller ( 29 ). 
     
     
         23 . The pump of  claim 21 , wherein the arm ( 28 ) has a rest rotational position where the roller does not contact the compression tube. 
     
     
         24 . The pump of  claim 23 , wherein the second pump housing portion ( 20   a ) is hingedly attached to the first pump housing portion ( 20   b ). 
     
     
         25 . The pump of  claim 23 , further comprising a sensor ( 36 ) for sensing that the second pump housing portion ( 20   a ) is positioned in a closed position relative to the first pump housing portion ( 20   b ). 
     
     
         26 . The pump of  claim 14 , further comprising a sensor ( 37 ) for sensing that the cassette housing ( 12 ) is disposed in the cavity ( 26 ). 
     
     
         27 . The pump of  claim 14 , wherein the lower cassette housing portion ( 46   b ) includes an annular sidewall ( 50 ) and a shoulder ( 52 ) extending from the annular sidewall, the upper cassette housing portion ( 46   a ) includes an annular sidewall ( 54 ), and the annular sidewalls ( 50 ,  54 ) of the lower and upper cassette housing portions mate together to form the compression surface ( 58 ), where the upper cassette housing portion sidewall ( 54 ) is positioned a fixed distance away from the shoulder ( 53 ) to define the channel ( 58 ). 
     
     
         28 . The pump of  claim 14 , wherein one of the lower and upper cassette housing portions includes tabs ( 48 ) for engaging the other of the lower and upper cassette housing portions. 
     
     
         29 . The pump of  claim 23 , wherein the arm ( 28 ) has a second rest rotational position where the roller ( 29 ) forms a temporary pinch-valve by temporarily stalling the moving occlusion of the compression tube ( 60 ).