Needle-less injection instrument

Abstract

In this injection instrument, the piston pump (A) is connected releasably to a drive motor (B), the working piston (5) of which is arranged displaceably in a cylindrical bore (6) of the motor housing (1). So that the piston pump (A) can be coupled to and uncoupled from the drive motor (B) by simple manipulations under sterile conditions and so that a ram play independent of the particular piston stroke is present between the piston pump and drive motor, the pump housing (20) has on the pump head (17) an annular groove (18) and a pair of flattened portions (22, 23) which are parallel to one another and reach to the bottom of the annular groove (18). The pump plunger (2) on the peg (8) projecting from the pump chamber (7) of the pump housing (20) is provided with two equally deep annular grooves (9, 10) located next to one another and with two pairs of flattened portions (11, 12, 13, 14) which are each parallel to one another and which reach to the bottom of the annular grooves (9, 10), one pair of flattened portions (11, 12 or 13, 14) extending only from the annular groove (9) to the annular groove (10 ) and being arranged perpendicularly to the second pair of flattened portions. Two pins (15, 16, 27, 28) are arranged, parallel to one another, respectively in the motor housing (1) and in a bore (19) in the piston shaft (4) and engage into the annular groove (18) of the pump housing (20) and the annular grooves (9) and (10) of the pump plunger (2). The pump plunger (2) and the piston shaft (4) are provided with devices preventing them from rotating in their housings.

Dependencies are inferred from the claim text.