Snap-fit ​​plunger rod

Abstract

This "plunger rod" is used in an "infusion pump system". (1) As shown in Reference Figure 1, the "infusion pump system" consists of a reusable "drive unit" and a disposable "reservoir," to which a drug vial is connected via an adapter. The "engaging member" is fixed to the "plunger head" inside the "reservoir." A "release member" is also fixed to the base end of the "reservoir." (2) With the "drive unit" and the "reservoir" connected, when the "plunger rod" is extended from the "drive unit" side by the motor and gear train, the "plunger rod" passes through the "release member" and enters the "reservoir," and the head of the "plunger rod" snaps into the "engaging member," connecting the "plunger rod" and the "plunger head" (Reference Figure 2). (3) When the plunger rod is pulled into the drive unit by the motor and gear train, the release member comes into contact with the engaging member, opening the claw portion of the engaging member. This disengages the connection between the plunger rod and the engaging member, and the plunger rod is retracted into the drive unit (see Figure 3).

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