Doseringsenhet för dosering av flera mätta mängder av en vätska, såsom ett insulinpreparat, ur en ampull

摘要

A dosage unit for dosing a number of measured quantities of a liquid, such as an insulin preparation, from a separate cartridge (2), where the dosage unit comprises a cylindrical casing for the cartridge (2). At the distal end the casing (1) is provided with means for fastening a liquid outlet needle (5). The dosage unit comprises furthermore a piston rod (8) activating a piston (4) in the cartridge (2). An adjustment means (18) is pivotally mounted on the casing and determines by way of adjustment the length of the stroke of the piston rod. A ratchet device (10, 11) is situated between the casing (1) and the piston rod (8), said ratchet device allowing displacement of said piston rod (8) towards the distal end of the casing (1) and preventing a displacement thereof in the opposite direction. The adjustment means (18) is non-displaceably mounted on the casing (1), and the piston rod (8) is provided with an external thread (12) and prevented from rotating relative to the casing (1). A nut means (13) is provided between the piston rod (8) and the adjustment means (18) said nut means engaging by way of an internal thread the thread (12) of the piston rod (8) and on the outside engaging in an axially displaceable manner the adjustment means (18). A rotation of the adjustment means (18) involves a rotation of the nut means (13) relative to the piston rod and consequently a displacement of an indicator (21) fixedly connected to the nut means (13) and protruding from the end of the adjustment means (18). The indicator (21) is provided with a measuring scale indicating the extent of its axial displacement relative to the adjustment means and consequently the desired dosing quantity, whereby the dosing is carried out by pressing the piston rod (8) by way of the indicator (21) while pressing it back towards the interior of the adjustment means (18)