| 摘要 |
A needleless injection device comprising a cylinder for medicine having an injection nozzle at a forward end thereof and an opening at its rearward end; a piston sliding in the cylinder through said open end, in use, to drive the medicine through the nozzle; a ram to drive the piston into the cylinder and having a longitudinal axis; and a mechanical energy accumulator to drive the ram when discharged and disposed between the ram and a discharge assembly, a rear end of the ram extending into said discharge assembly; wherein the discharge assembly comprises a retention member fixed in the assembly, said retention member having a plurality of retention elements spaced around and adapted to locate on the ram when in a charged position of the ram, and a release ring surrounding said retention elements to prevent radial outward displacement thereof and discharge of the ram; and wherein axial displacement of said release ring releases said retention elements and causes discharge of the ram by said accumulator; characterised in that said retention elements are integral with said retention member and each has an enlarged head which can move into and out of engagement with a groove or recess on the ram by deformation of the material of said retention member.
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