Cylindrical Pushrod for Controllable Needle Retraction

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Solution Overview

Problem

Existing needle-retracting safety injectors lack controllable retraction mechanisms, leading to potential patient injury and operational inconvenience, as well as issues with the firm and releasable fixation of the needle stand and residual drug liquor.

Innovation Solution

A cylindrical pushrod with a clamping structure and a compressible needle-stopping piece is introduced, allowing for controlled needle retraction and reducing residual drug liquor, featuring a push pole, underpinned piece, and protective sleeve for safe operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If automatic needle retraction is implemented, then needle retraction function is achieved, but patient safety deteriorates due to potential needle movement during retraction

Engineering Contradiction:

Improveautomatic needle retractionVSAvoidpatient injury from needle movement

Core Design Contradiction:

Extent of automationVSObject-affected harmful factors

Solution Approach 1:

The needle retraction function is activated only after the trigger is fully released, ensuring the needle remains stationary during the critical injection phase. The system prepares the retraction mechanism in advance but executes it only when safe, preventing unintended needle movement during injection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The trigger mechanism provides feedback control by linking the retraction activation to the actual release of the trigger. This ensures the system only initiates retraction when the operator has completed the injection and released the control, creating a safe feedback loop that prevents premature or unintended retraction.

Inventive Principle:

Principle #23Feedback

2Extent of automation

If automatic needle retraction is implemented, then needle retraction function is achieved, but operational convenience deteriorates due to conflict with standard injection procedure

Engineering Contradiction:

Improveautomatic needle retractionVSAvoidmedical personnel operation convenience

Core Design Contradiction:

Extent of automationVSEase of operation

Solution Approach 1:

The system performs needle retraction automatically without requiring additional manual intervention from the medical personnel. The trigger release itself activates the retraction sequence, making the system self-serving and eliminating the need for operators to change their standard procedure.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The retraction mechanism is pre-configured to activate automatically upon trigger release, so the medical personnel do not need to manually initiate or control the retraction process. This preliminary setup maintains operational simplicity while achieving automation.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If simple fixed structure is used for needle stand, then device complexity is reduced, but fixation reliability deteriorates

Engineering Contradiction:

Improvefixed structure complexityVSAvoidneedle stand fixation reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The fixed structure is divided into multiple functional segments: the trigger mechanism, the release latch, and the needle stand mounting. Each segment performs a specific function, allowing the overall system to achieve reliable fixation through coordinated simple components rather than a single complex structure.

Inventive Principle:

Principle #1Segmentation

4Extent of automation

If pushrod pushes needle stand to release fixation, then needle retraction is enabled, but residual drug liquor increases

Engineering Contradiction:

Improveneedle retraction activationVSAvoidresidual drug liquor

Core Design Contradiction:

Extent of automationVSLoss of substance

Solution Approach 1:

The system is designed to complete the injection process and expel residual liquor before activating the retraction mechanism. The trigger release sequence ensures that any remaining drug is pushed out first, then the needle stand is released for retraction, minimizing drug loss.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7331936B2Cylindrical pushrod for needle-retracting safety injector and the needle-retraction controllable safety injector

Publication Date: 2008.02.19 LIU WENJIE

AI summary

The invention provide a cylindrical pushrod for the syringe needle-retracting safety injector, comprising an outer cylinder, an inner cylinder, a push pole, an underpinned piece and a seal gasket; the push pole is set at the front end of chamber of outer cylinder, its front end appears as a tubular shape or projects partially in the longitudinal direction, the back end of push pole is supported on the underpinned piece; the underpinned piece is set at the front end of the chamber of outer cylinder and supports the push pole; the cylinder wall of the inner cylinder supports the underpinned piece; a clamping structure is set at the tail of this cylindrical pushrod. With the safety injector with the cylindrical pushrod according to the invention, the medical personnel can control the time of the needle retraction as desired, and is not necessary to change their habitual injection practice, and thereby the safety injector is easy to operate. The invention also provide a safety injector, which can not only carry out the controllable retraction of the needle but also has a simple and crafty fixed structure of the needle stand to achieve the effect of reliable fixation as well as releasing with ease.