Automatic fluid injector

摘要

An automatic fluid injector for accurately injecting preselected quantities of fluid specimens into an inlet of analytical instrument. The overall combination includes (a) the fluid injector sub-assembly, (b) an injector feed assembly for automatically continuously purging, cleaning and filling the barrel of said fluid injector sub-assembly and (c) a magazine, or feed tray, for transporting one or a plurality of vials of fluid specimens to the injector feed assembly for pick-up of the fluid specimen, and delivery to the barrel of said fluid injector sub-assembly. A feature of the invention is that fluid specimen can be passed from the extreme rearward end of the barrel of the fluid injector sub-assembly, entirely through the barrel and needle to purge, clean and remove contaminants as from previous specimens. Another feature is that the fluid specimen is ejected from the fluid injector sub-assembly, on closure of the valve thereof, by the forward movement of the barrel relative to the needle such that the needle moves rearwardly into the barrel to displace and eject fluid specimen through the dispensing end of the needle. An accurately measured fluid specimen is trapped on closure of the valve, after adequate flow through to remove contaminants, the amount of fluid specimen to be injected being predetermined by the preset volume to be displaced from the barrel by the extent of its forward movement which moves the rearward end of the needle into the barrel.