Patent ID: 8961156
Filing Date: 2015-02-24
Classification: F04B

Abstract:
1. A fluid conveying device which ejects a fluid, the device comprising: an elastic tube; a cam having n (n being an integer equal to or greater than 2) protrusions; plural pressing shafts arranged along the tube between the tube and the cam; a driving unit which rotates the cam to sequentially push the plural pressing shafts by the protrusions 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 calculates a cam rotation angle in relation to a cumulative ejection volume, using only two approximation formulae, a first approximation formula of the two approximation formulae expresses an ejection area where the cumulative ejection volume increases in proportion to the rotation angle of the cam and a second approximation formula that expresses a constant area where the cumulative ejection volume does not increase or decrease even if the cam rotates, and which drives the driving unit until the detection unit detects a rotating position of the cam corresponding to a designated cumulative ejection volume, wherein during a cam rotation cycle, the cumulative ejection volume increases in the ejection area as the cam rotates during approximately two-thirds of the rotation cycle and wherein the cumulative ejection volume does not increase or decrease in the constant area as the cam rotates during approximately one-third of the rotation cycle, wherein the constant area includes a first area where the cumulative ejection volume is substantially constant, a second area where the cumulative ejection volume decreases, and a third area where the cumulative ejection volume increases, the decrease in the second area being approximately equal to the increase in the third area.