CA2135707C — Injector with retractable shroud

USPTO Abstract

An injector (10) having a needle (14) which is exposed by a retractable shroud (13). Mounted within the body (11) of the injector (10), is a first interacting piston (30) and cylinder (31) which cooperate to enclose a first space (33) which receives the liquid to be injected. A second interacting piston (26) and cylinder (27) cooperate to enclose a second space (28). A gas under pressure is delivered to the second space (28) to cause movement of the second piston (26). The second piston (26) is attached to the first piston (30) and therefore moves with it. The shroud (13) is operatively associated with a valve (35) to regulate the delivery of the gas under pressure to the space (28) to cause operation of the injector (10). A user of the injector (10) grips the body (11) by means of a handle portion (12) and presses the injector (10) against the skin of the animal. This causes retraction of the shroud (13) as the needle (14) penetrates. That retraction of the shroud (13) then causes actuation of the valve (35) to cause operation of the injector (10).