Method and equipment for dosing small amounts of liquid quantitatively

Abstract

The invention relates to a method and equipment for quantitatively dosing small amounts of liquid, especially in clinical or other similar wet-chemical analyzers. The dosing employs a liquid space, the volume of which can be changed and which is connected to a dosing channel so that, by increasing or decreasing the volume of the liquid space, a suction or an injection through the dosing channel is achieved. The liquid space is formed by flexible bellows which are freely movable back and forth to provide the reversible deformations which change the volume of the liquid space. The movements are effected using an actuator which is connected to the bellows without transmissions containing sliding surfaces. The actuator comprises precisely repeatable positions and is calibrated according to the invention by measuring the sizes of the dosages produced by the movements between the positions. The dosing is effected after that by selectively repealing the calibrated movements. The actuator can be formed by a stepper motor, and a cam shaft rotated by the stepper motor propelling the bellows back and forth. The nonlinear interdependent relationship between the rotation of the shaft and the change in the volume of the liquid space makes possible a wide range of calibrated dosage sizes.

Dependencies are inferred from the claim text.