Liquid infusion apparatus

摘要

In a liquid infusion apparatus, an incremental linear encoder is arranged along the feeding shaft direction of the liquid infusion apparatus to directly monitor the movement and position of a carriage part which applies an action to a plunger. A detecting sensor is provided at a starting point of a remaining liquid quantity small region to recognize the absolute position at said region by using feed-back pulses from said encoder. A pressing device for pressing a flange of the plunger to a plunger receiving portion of a slider by holding arms is provided. A pressure sensor Is arranged between said plunger receiving portion and the slider to detect a negative pressure applied to the plunger in such a manner that the other operation states of pressure are detected based on a detected value of pressure at which the flange is pressed to the plunger receiving portion. The holding arms which are able to open are moved in the moving direction of the slider to press for holding the flange of the plunger to the plunger holding portion of the slider. The holding arm for press holding the flange of the plunger with the slider is supported rotatably freely by ashaft and urged to rotate by aspring in the clockwise direction. <??>A projection which is engaged with asmall projection provided an end of the holding arms is provided on a lever, so that the holding arm can be rotated in the counterclockwise direction by said projection. A half-nut releasing device interlocking with a retracting lever provided on the slider for disengaging the half-nut from a feed screw Is composed of means to urge the half-nut by a release cam having a step portion and of means to press the flange of the plunger against the slider by the holding arm for holding the flange of the plunger. A one-way clutch for transmitting a driving force in the syringe pushing direction is arranged between the output shaft of a prime mover and the feed screw. <IMAGE>