초록 ▼

In a displacement system for controlled infusion of a liquid from a cartridge comprising a tubular vessel (1), which is at a rear end closed by a piston (3) which may be forced by a piston rod (8) moving into the vessel (1) in the axial direction thereof to press out the liquid through an outlet (2)

In a displacement system for controlled infusion of a liquid from a cartridge comprising a tubular vessel (1), which is at a rear end closed by a piston (3) which may be forced by a piston rod (8) moving into the vessel (1) in the axial direction thereof to press out the liquid through an outlet (2) arranged at a front end of the vessel (1), the piston rod (8) is provided as a flexible incompressible construction which is by a piston rod guide (9) behind the rear end of the cartridge deflected away from the axis of this cartridge, preferably 180.degree.. The piston rod guide (9) has a guiding track comprising a curved part and linear parts at each end of the curved part ensuring that the piston rod is guided along a length (a) in the direction of the axis of the cartridge which length (a) is longer than the distance (b) between the two axes of the piston rod parts projecting from the piston rod guide. The guiding track is further elaborated to the very shape which the curved part of the piston rod will spontaneously adopt when its end portions are kept parallel.

대표청구항 ▼

[ We claim:] [1.] A displacement system for controlled infusion of a liquid from a cartridge, said system comprising:a tubular vessel having a front end and a rear end, the rear end being closed by a piston which is movable by a piston rod moving into the vessel in the axial direction thereof to pre

[ We claim:] [1.] A displacement system for controlled infusion of a liquid from a cartridge, said system comprising:a tubular vessel having a front end and a rear end, the rear end being closed by a piston which is movable by a piston rod moving into the vessel in the axial direction thereof to press out the liquid through an outlet arranged at the front end of the vessel, the piston rod being a flexible incompressible construction which at a position behind the rear end of the tubular vessel is deflected away from the axis of the cartridge by a piston rod guide provided behind the rear end of the cartridge and deflects the piston rod 180.degree. so that parallel portions of the piston rod projects from one side of the piston rod guide, the piston rod guide has a guide track having an upper curved part and a lower linear part at each end of the curved part, each of the linear parts having a first length in the direction of the projecting parallel portions, said first length for each of the linear parts extending from a side of the piston rod guide from which the respective portion projects to an end of the curved part, a second length taken from said side of the piston rod guide to the center of the piston rod at the top of the curved part, said second length being equal to the sum of the length of one of the linear parts plus the radius of the curved part, said second length being equal to or larger than the distance between the axes of the two extending parallel portions, wherein the piston rod is formed by a flexible helix with narrowly adjacent turns of windings, the flexible helix having a coiling ratio EQU r.sub.coil =[d.sub.helix-d.sub.wire ].div.d.sub.wire <5.0, re d.sub.helix is an outer diameter of the wound helix, and d.sub.wire is a diameter of the wire.