To solve the problem in which: hysteresis and a nonlinear relationship between a rotation command value of a motor and the actual operational speed of a plunger often occur in a liquid pump in the prior art due to backlash and play of a driving device, the step-out of the motor and the like; though suitable rotation command values are given to the motor in this composition, the plunger is not actually displaced as desired, and the liquid feed rate of the pump is changed intermittently; and the intermittent change in the liquid feed rate causes fluctuation in the flow rate of solvent passing through a separation column and the mixing ratio of solvent and reduces the accuracy of results detected on chromatograms.
A liquid analyzer comprises: a pump controller reading values measured by pressure detection means and giving command values to a motor driver; liquid feed pumps in which a first plunger and a second plunger conduct compression operations alternately and which continuously feeds liquid; and displacement detection means in which the output values of electric signals change when the first plunger or the second plunger reaches a predetermined position in a reciprocating stroke.
ENOKI HIDEO
KUBO SHINTARO
AKIEDA DAISUKE
| JPH03160175A | 1991-07-10 | |||
| JP2005055179A | 2005-03-03 | |||
| JPH0219670A | 1990-01-23 | |||
| JP2012032187A | 2012-02-16 |
Yuji Toda
Shigemi Iwasaki