| 摘要 |
A needleless injector syringe includes a tubular barrel containing a first chamber for receiving a liquid, a nozzle on a front end of the barrel, a piston which drives a plunger for discharging the liquid through the nozzle, a second chamber in which the piston slides, a third chamber in fluid communication with the second chamber for receiving gas from said second chamber during forward movement of the piston, and for carrying gas to the second chamber to cause the piston to retract, and a breach plug closing a rear end of the barrel for directing gas under pressure alternately against the rear end of the piston and to the third chamber for driving the piston between the discharge position and a retracted position. |
