Medical injector with ratcheting plunger

摘要

A medical injector has 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 to engage the plunger, wherein the indexer is configured to allow the plunger to displace distally toward a distal end of the body but not proximally toward 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 bypass 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.

主权项

1. A medical injector, comprising:
a body having a distal end and a proximal end; a displaceable plunger disposed in the body, the plunger having a plurality of spaced-apart ratchet teeth disposed along the length thereof; at least one indexer formed to engage the plunger, wherein the indexer is configured to allow the plunger to displace distally toward the distal end of the body but not proximally toward the proximal end of the body; an actuator having an engagement portion formed to engage one or more of the ratchet teeth, wherein the actuator is displaceable to a ready state, the engagement portion being displaced proximally relative to the plunger upon the actuator being displaced to the ready state, the indexer preventing proximal movement of the plunger thereby allowing the engagement portion to bypass one or more of the ratchet teeth upon the actuator being displaced to the ready state, and wherein the actuator is displaceable from the ready state to cause actuation of the medical injector, the displacement from the ready state causing 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; and a rotary knob rotatably disposed at a proximal end of the body; wherein one of the actuator and an interior of the body comprises an axial groove and the remaining one of the actuator and the interior of the body comprises a corresponding axial key slidably received in the axial groove to guide axial displacement of the actuator relative to the body and prevent rotation of the actuator relative to the body; wherein one of the actuator and the rotary knob comprises a groove with a substantially helical portion and the remaining one of the actuator and the rotary knob comprises a corresponding key slidably received in the groove; and wherein rotation of the rotary knob induces displacement of the key relative to the groove, thereby axially displacing the actuator relative to the body.