Variable Piston Rate for Pharmaceutical Injection Leakage

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Solution Overview

Problem

Conventional pharmaceutical injection devices experience liquid leakage from the injection needle during pharmaceutical mixing due to a constant push-in rate of the piston, leading to uncontrolled mixing and potential splashing.

Innovation Solution

The device adjusts the push-in rate of the piston, setting V2 lower than V1 when the separation gasket reaches the bypass, and further reduces the rate during air venting and injection to minimize leakage, ensuring a controlled flow of liquids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a constant push-in rate is used during pharmaceutical mixing, then the mixing process is simple and fast, but liquid pharmaceutical squirts out from the injection needle due to uncontrolled pressure rise

Engineering Contradiction:

Improvemixing speedVSAvoidliquid leakage from injection needle

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The push-in rate of the piston is changed from constant to variable during the mixing process. The controller adjusts the push-in rate dynamically: using a first push-in rate when the separation gasket has not reached the bypass, and switching to a second (lower) push-in rate when the separation gasket reaches the bypass to prevent liquid squiring while maintaining mixing effectiveness

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The push-in rate parameter is changed based on the position of the separation gasket. The controller detects when the separation gasket reaches the bypass and adjusts the push-in rate parameter from a higher value to a lower value, thereby controlling the pressure rise and preventing liquid leakage from the injection needle

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the push-in rate is reduced to prevent liquid squiring, then liquid leakage is minimized, but the mixing process becomes slower and less efficient

Engineering Contradiction:

Improveliquid leakage from injection needleVSAvoidmixing speed

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The piston push-in process is divided into two distinct periods or phases: a first period with a higher push-in rate when the separation gasket is moving toward the bypass, and a second period with a lower push-in rate when the separation gasket reaches the bypass. This periodic adjustment of the push-in rate prevents liquid leakage while maintaining overall mixing efficiency

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS9192722B2Pharmaceutical injection device

Publication Date: 2015.11.24 PHC HLDG CORP

AI summary

This pharmaceutical injection device comprises a main body case (2) having an injection needle extension/retraction opening (1); a pharmaceutical syringe mounting portion (3) provided inside the main body case (2); a piston (5) capable of moving relative to the pharmaceutical syringe mounting portion (3); a drive mechanism (6) for the piston (5); a controller (7) that is electrically connected to the drive mechanism (6); and an orientation sensor (8) that is electrically connected to the controller (7). The controller (7) controls the speed of the piston (5) in order to reduce liquid leakage during pharmaceutical mixing.