Medical injector with ratcheting plunger

摘要

A medical injector is provided herein having a body with a displaceable plunger. The plunger includes a plurality of spaced-apart ratchet teeth disposed along the length thereof. At least one indexer is provided formed to engage the plunger, wherein the indexer is configured to allow the plunger to displace distally towards a distal end of the body but not proximally towards a proximal end of the body. The medical injector also includes an actuator having an engagement portion formed to engage one or more of the ratchet teeth. The actuator is displaceable to a ready state, the engagement portion being displaced proximally relative to the plunger with the actuator being displaced to the ready state. The indexer prevents proximal movement of the plunger thereby allowing the engagement portion to by-pass one or more of the ratchet teeth with the actuator being displaced to the ready state. In addition, the actuator is displaceable from the ready state to cause actuation of the medical injector. The displacement from the ready state causes distal displacement of the engagement portion with the engagement portion engaging one or more of the ratchet teeth and causing distal displacement of the plunger with the engagement portion. Advantageously, the subject invention provides a plunger for a medical injector which may be controllably advanced with a minimum number of cooperating parts.

主权项

1. A medical injector comprising:
a body having a distal end and a proximal end; a displaceable plunger disposed in said body, said plunger having at least one set of ratchet teeth, each set having a plurality of spaced-apart ratchet teeth disposed along the length thereof; at least one indexer formed to engage said plunger, wherein said indexer is configured to allow said plunger to displace distally towards said distal end of said body but not proximally towards said proximal end of said body; and an actuator having a frame pivotally connected thereto at a first end of the frame to rotate relative to the actuator, said frame being pivotally connected at a second, opposing frame end to said body to rotate relative to said body, said frame having an engagement portion formed to engage one or more of said ratchet teeth, said plunger being disposed within said frame; wherein said actuator is displaceable to a ready state, said engagement portion being displaced proximally relative to said plunger with said actuator being displaced to said ready state, said indexer preventing proximal movement of said plunger thereby allowing said engagement portion to by-pass one or more of said ratchet teeth with said actuator being displaced to said ready state; wherein, said actuator is displaceable from said ready state to cause actuation of the medical injector, said displacement from said ready state causing distal displacement of said engagement portion with said engagement portion engaging one or more of said ratchet teeth and causing distal displacement of said plunger with said engagement portion; wherein said indexer and said frame engage the same set of ratchet teeth; wherein said frame comprises at least one side support extending from said first end to said second end; and said engagement portion is disposed on said side support.