Peristaltic pump for imaging apparatus

Abstract

A pump for pumping fluid using peristaltic compression. The pump includes a rotor and a roller. The rotor includes a first cam that extends along a circumferential direction relative to the rotor. The first cam has first and second dwells. The roller is movable relative to the rotor between the first dwell and the second dwell of the first cam as the rotor rotates in a first direction and a second direction. The rotor includes a second cam extending radially from its shaft for engaging the roller. Contact between the second cam and the roller increases frictional resistance between the rotor and the roller as the roller translates between the first and second dwells of the first cam such that the roller transitions between the first and second dwells without slipping.

1 . A pump for pumping fluid using peristaltic compression, comprising:
 a body including an inner surface defining a hollow portion;   a tubing arranged to extend along the inner surface;   a rotor including a shaft defining a rotational axis thereof, and a first cam extending along a circumferential direction relative to the rotor, the first cam having a first dwell and a second dwell; and   a roller movable relative to the rotor between the first dwell and the second dwell of the first cam as the rotor rotates about the rotational axis in a first direction and a second direction, the roller operative to allow the tubing to be vented when positioned in the first dwell of the first cam in which the roller unoccludes the tubing as the rotor is rotated in the first direction and to compel fluid to flow through the tubing when positioned in the second dwell of the first cam in which the roller occludes the tubing against the inner surface as the rotor is rotated in the second direction,   wherein the rotor includes at least one second cam extending radially from the shaft for engaging the roller so as to increase frictional resistance between the rotor and the roller as the roller translates between the first and second dwells of the first cam.   
     
     
         2 . The pump of  claim 1 , wherein the roller is free from any contact with the at least one second cam when positioned in the first and second dwells of the first cam. 
     
     
         3 . The pump of  claim 1 , wherein a first frictional force between the roller and the at least one second cam is greater than a second frictional force between the roller and the first cam. 
     
     
         4 . The pump of  claim 1 , further comprising an annular ring disposed at an end of the roller, the rotor further including a third cam extending along a circumferential direction relative to the rotor and adjacent the end of the roller such that the annular ring engages the third cam so as to increase frictional resistance between the rotor and the roller as the roller translates between the first and second dwells of the cam. 
     
     
         5 . The pump of  claim 4 , wherein the annular ring is free from any contact with the third cam when the roller is positioned in the first and second dwells of the first cam. 
     
     
         6 . The pump of  claim 4 , wherein a first frictional force between the annular ring and the third cam is greater than a second frictional force between the roller and the first cam. 
     
     
         7 . The pump of  claim 4 , wherein the annular ring includes an o-ring. 
     
     
         8 . The pump of  claim 1 , further comprising a gear attached to an end of the roller, the rotor further including a gear section extending along a circumferential direction relative to the rotor and adjacent the end of the roller such that the gear of the roller meshes with the gear section as the roller translates between the first and second dwells of the first cam. 
     
     
         9 . The pump of  claim 8 , wherein the gear of the roller is free from any contact with the gear section when the roller is positioned in the first and second dwells of the first cam. 
     
     
         10 . A peristaltic pump, comprising:
 a housing having an inner wall;   a tubing arranged to extend along the inner wall;   a rotor rotatably mounted in the housing and including a shaft defining a rotational axis of the rotor;   a first cam disposed at a first longitudinal end of the shaft and extending along a circumferential direction relative to the rotor, the first cam having a first dwell and a second dwell that are eccentric relative to the rotational axis of the rotor;   a roller movable relative to the rotor between the first dwell and the second dwell of the first cam as the rotor rotates in a first direction and a second direction, the roller operative to allow the tubing to be vented when in the first dwell of the first cam in which the roller unoccludes the tubing as the rotor is rotated in the first direction and to compel fluid to flow through the tubing when in the second dwell of the first cam in which the roller occludes the tubing against the inner wall as the rotor is rotated in the second direction;   an annular ring disposed at an end of the roller; and   a second cam disposed at a second longitudinal end of the shaft and extending along a circumferential direction relative to the rotor and adjacent the end of the roller such that the annular ring engages the second cam so as to increase frictional resistance as the roller translates between the first and second dwells of the first cam.   
     
     
         11 . The peristaltic pump of  claim 10 , wherein the annular ring is free from any contact with the second cam when the roller is positioned in the first and second dwells of the first cam. 
     
     
         12 . The peristaltic pump of  claim 10 , wherein a first frictional force between the annular ring and the second cam is greater than a second frictional force between the roller and the first cam. 
     
     
         13 . The peristaltic pump of  claim 10 , wherein the annular ring includes an o-ring. 
     
     
         14 . The peristaltic pump of  claim 10 , wherein the rotor further includes at least one third cam extending radially from the shaft for engaging a central portion of the roller so as to substantially increase frictional resistance between the rotor and the roller as the roller translates between the first and second dwells of the first cam. 
     
     
         15 . The peristaltic pump of  claim 14 , wherein the at least one third cam causes the roller to remain substantially parallel relative to the rotational axis of the rotor when the roller transitions between the first and second dwells of the first cam. 
     
     
         16 . The peristaltic pump of  claim 14 , wherein the roller is free from any contact with the at least one third cam when positioned in the first and second dwells of the first cam. 
     
     
         17 . A peristaltic pump, comprising:
 a housing having an inner wall;   a tubing arranged to extend along the inner wall;   a rotor rotatably mounted in the housing and including a shaft defining a rotational axis thereof;   a first cam disposed at a first longitudinal end of the shaft and extending along a circumferential direction relative to the rotor, the first cam having a first dwell and a second dwell that are eccentric relative to the rotational axis of the rotor;   a roller movable relative to the rotor between the first dwell and the second dwell of the first cam as the rotor rotates in a first direction and a second direction, the roller operative to allow the tubing to be vented when positioned in the first dwell of the first cam in which the roller unoccludes the tubing as the rotor is rotated in the first direction and to compel fluid to flow through the tubing when positioned in the second dwell of the first cam in which the roller occludes the tubing against the inner wall as the rotor is rotated in the second direction;   a gear attached to an end of the roller; and   a gear section disposed at a second longitudinal end of the shaft and extending along a circumferential direction relative to the rotor and adjacent the end of the roller such that the gear of the roller meshes with the gear section as the roller translates between the first and second dwells of the first cam.   
     
     
         18 . The peristaltic pump of  claim 17 , wherein the gear of the roller is free from any contact with the gear section when the roller is positioned in the first and second dwells of the first cam. 
     
     
         19 . The peristaltic pump of  claim 17 , further comprising at least one second cam extending radially from the shaft for engaging a central portion of the roller so as to substantially increase frictional resistance between the rotor and the roller as the roller translates between the first and second dwells of the first cam. 
     
     
         20 . The peristaltic pump of  claim 19 , wherein the roller is free from any contact with the at least one second cam when positioned in the first and second dwells of the first cam. 
     
     
         21 . A peristaltic pump, comprising:
 a body including an inner surface defining a hollow portion;   a tubing arranged to extend along the inner surface;   a rotor including a shaft and a first cam at a longitudinal end of the shaft extending along a circumferential direction relative to the rotor, the rotor being rotatable within the hollow portion about a rotational axis defined by the shaft and the first cam having a first dwell and a second dwell; and   a roller movable relative to the rotor between the first dwell and the second dwell of the first cam as the rotor rotates in a first direction and a second direction, respectively, the roller operative to allow the tubing to be vented when positioned in the first dwell of the first cam in which the roller unoccludes the tubing as the rotor is rotated in the first direction, and to compel fluid to flow through the tubing when positioned in the second dwell of the first cam in which the roller occludes the tubing against the inner surface as the rotor is rotated in the second direction;   wherein the rotor includes at least one second cam extending radially from the shaft for engaging a central portion of the roller so as to increase frictional resistance between the rotor and the roller as the roller translates between the first and second dwells of the first cam.