Fluid conveying device and driving method for fluid conveying device

Abstract

A fluid conveying device includes: a tube; a cam having protrusions; fingers arranged along the tube between the tube and the cam; a driving rotor which rotates the cam to sequentially push the fingers by the protrusions in a flowing direction of a fluid, repeatedly pressuring and opening of the tube, driving the cam; a detection unit which detects a rotating position of the cam; a control unit which calculates a cam rotation angle along a cumulative ejection volume, using a first approximation formula for an ejection area H where the cumulative ejection volume increases substantially in proportion to the rotation angle of the cam and a second approximation formula for a constant area J where the cumulative ejection volume little increases or decreases even if the cam rotates, driving the driving rotor until a rotating position of the cam corresponding to a designated cumulative ejection volume is reached.

What is claimed is: 
     
         1 . A fluid conveying device which ejects a fluid, the device comprising:
 an elastic tube;   a plurality of pressing shafts arranged along the tube;   a cam having a plurality of fixed protrusions selectively contacting the plurality of pressing shafts, each protrusion including a first region over which a cumulative ejection volume of the fluid ejected from the elastic tube increases based on rotation of the cam and a second region over which there is little increase or decrease in the cumulative ejection volume of the fluid ejected from the elastic tube based on rotation of the cam;   a driving unit which rotates the cam to sequentially push the plurality of pressing shafts by the cam; and   a control unit which controls the driving unit in rotating the cam,   wherein, when a predetermined volume is conveyed along the elastic tube, the control unit stops rotation of the cam at the first region.   
     
     
         2 . The fluid conveying device of  claim 1 , wherein the first region terminates below a vertex of each protrusion. 
     
     
         3 . The fluid conveying device of  claim 1 , wherein the second region terminates at an end of each vertex of each protrusion. 
     
     
         4 . The fluid conveying device of  claim 1 , wherein the second region includes a vertex of each protrusion. 
     
     
         5 . The fluid conveying device of  claim 1 , further comprising a third region at which the cumulative ejection volume of the fluid decreases based on the rotation of the cam. 
     
     
         6 . The fluid conveying device of  claim 1 , further comprising a fourth region at which the cumulative ejection volume of the fluid is compensated for backflow of the fluid. 
     
     
         7 . A fluid conveying device which ejects a fluid, the device comprising:
 an elastic tube;   a cam having a plurality of regions formed on an outer surface of the cam, the plurality of regions comprising:
 a first region at which a cumulative ejection volume of the fluid increase based on the rotation of the cam; 
 a second region at which the cumulative ejection volume of the fluid does not increase or decrease based on the rotation of the cam; 
 a third region at which the cumulative ejection volume of the fluid decreases based on the rotation of the cam; and 
 a fourth region at which the cumulative ejection volume of the fluid is compensated; 
   a plurality of pressing shafts arranged along the tube between the tube and the cam;   a driving unit which rotates the cam to sequentially push the plurality of pressing shafts by the cam in a flowing direction of the fluid, and thus repeats pressurized closure and opening of the tube;   a detection unit which detects a rotating position of the cam; and   a control unit which controls rotation of the cam by the driving unit through the first region, the second region, the third region, and the fourth region,   wherein, when the predetermined volume is conveyed along the tube, the control unit stops rotation of the cam at the first region.   
     
     
         8 . The fluid conveying device of  claim 7 , wherein the cam includes n (n being an integer equal to or greater than 2) protrusions, each protrusion extending over at least a portion of the first and second regions. 
     
     
         9 . The fluid conveying device of  claim 8 , wherein the second region includes a vertex of each protrusion, the vertex being formed concentrically about a center of rotation of the cam. 
     
     
         10 . The fluid conveying device of  claim 7 , wherein fluid backflows into the tube at the third region of the cam. 
     
     
         11 . The fluid conveying device of  claim 7 , wherein the fourth region compensates for fluid backflow into the tube at the third region of the cam rotation, the cumulative ejection volume at the end of the fourth region matches the cumulative ejection volume at the end of the second region. 
     
     
         12 . The fluid conveying device of  claim 7 , wherein over the second region, the third region, and the fourth region there is little increase or decrease in the cumulative ejection volume. 
     
     
         13 . The fluid conveying device according to  claim 7 , wherein in the constant area, a rotation speed of the cam is made higher than a rotation speed of the cam in the ejection area. 
     
     
         14 . A fluid conveying device which ejects a fluid, the device comprising:
 an elastic tube;   a cam having an outer surface with a plurality of fixed protrusions extending from the outer surface;   a plurality of pressing shafts arranged along the tube between the tube and the cam;   a driving unit which rotates the cam to sequentially push the plurality of pressing shafts by the cam in a flowing direction of the fluid; and   a control unit which controls rotation of the cam by the driving unit to rotate the cam through a first region, a second region, a third region, and a fourth region of the outer surface of the cam, wherein
 a first region of the outer surface corresponds with an increase in a cumulative ejection volume of the fluid from the rotation of the cam; 
 a second region of the outer surface correspond with no increase or decrease in the cumulative ejection volume of the fluid from the rotation of the cam; 
 a third region of the outer surface corresponds with a decrease in the cumulative ejection volume from the rotation of the cam; and 
 a fourth region of the outer surface corresponds with a compensation to the cumulative ejection volume of the fluid. 
   
     
     
         15 . The fluid conveying device of  claim 14 , wherein the first region is a slope part extending towards a vertex of each protrusion. 
     
     
         16 . The fluid conveying device of  claim 15 , wherein the second region extends from a location on the slope part below the vertex of each protrusion to the vertex. 
     
     
         17 . The fluid conveying device of  claim 16 , wherein the third region extends from the vertex to a portion of the outer surface near a start of the slope part, an inclination of the third region begin greater than the slope part. 
     
     
         18 . The fluid conveying device of  claim 17 , wherein the fourth region extends from the terminal end of the third region to the start of the slope part. 
     
     
         19 . The fluid conveying device of  claim 14 , wherein the second region commences before a vertex of each protrusion to accommodate variance in flow of fluid in the elastic tube.