Syringe Piston Retention Device for Pressure Filling

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Solution Overview

Problem

Existing syringes, particularly those with rigid plastic bodies, face challenges in effectively retaining the piston during filling by pressure, leading to potential ejection and compromising sterility in medical procedures like c-TACE, where conventional solutions provide inadequate retention and are either inefficient or complex.

Innovation Solution

A syringe design featuring a deformable retention device with a large contact area and spring-like properties, force-fitted into the syringe body, which surrounds the piston and applies radial force to prevent ejection, ensuring effective retention without damaging the sealing system and simplifying assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional retaining ring with a small finger is used to immobilize the piston, then the device complexity is reduced, but the retention efficacy is insufficient and the piston may be ejected during pressure filling

Engineering Contradiction:

Improvepiston retention efficacyVSAvoidretention device structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The retention device is made of deformable plastic material that can elastically deform during assembly and then exert radial retaining force on the piston. The flexibility of the material allows the device to be inserted in a compressed state and then expand to provide effective retention, resolving the contradiction between simple structure and effective retention.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The retention device changes its physical state from a compressed deformable state during assembly to an expanded rigid state during operation. This parameter change allows the same simple structure to provide both ease of assembly and effective piston retention under pressure filling conditions.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a piston with multiple separate parts and complicated initial assembly is used, then the piston retention is achieved, but the manufacturing cost and assembly complexity increase

Engineering Contradiction:

Improvepiston retentionVSAvoidassembly process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The retention device is divided into two parts (first part and second part) that can be assembled separately and then connected. This segmentation allows for easier manufacturing and assembly while still providing effective piston retention, as each part can be independently formed and then joined to create the complete retaining structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The retention device is inserted into the syringe body in a compressed state and then expands to its final shape, nesting the assembly process within the syringe body cavity. This nesting approach simplifies the overall assembly process by allowing the retention device to be installed in a compact form and then self-expand to provide retention.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Stability of the object's composition

If a rigid non-deformable plastic body is used, then the structural stability is improved, but the retention device cannot be easily assembled and may damage the sealing system

Engineering Contradiction:

Improvesyringe body structural stabilityVSAvoidretention device assembly

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The retention device is made of deformable plastic material that can elastically deform during assembly to navigate the rigid syringe body structure and sealing elements, then maintains its shape to provide stable retention. This flexibility-resilience combination resolves the contradiction between rigid body stability and easy assembly.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The deformable material of the retention device acts as a cushioning element during assembly, absorbing mechanical stresses that might otherwise damage the sealing system or rigid body structure. This beforehand cushioning allows safe installation while maintaining structural stability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The syringe effectively immobilizes the piston, preventing ejection during pressure-filled procedures, maintaining sterility and simplifying assembly, while avoiding costly and complex arrangements, thus enhancing the mechanical performance and user safety.

Implementation Method 1

a retention device (4) taken as a whole mounted around the piston (3) and force-fitted into the body (2), inside the chamber (C), from the second end (2B) of the body (2), the retention device (4) being deformable

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUSRE49516E1Syringe and method for assembling it

Publication Date: 2023.05.02 GUERBET SA

AI summary

A syringe comprising: a body delimiting a chamber; a piston able to slide in the chamber of the body along a longitudinal axis of the syringe, wherein the piston comprises a rod, a head, and a finger rest, which are all in one piece; and a deformable retention device designed to prevent the piston from leaving the body entirely, wherein the retention device is force-fitted in the chamber, extends around the piston over an angular sector strictly greater than 180° when it is in the assembled position, and has protruding external ribs which extend parallel to the longitudinal axis and are plastically deformable when the retention device is assembled in the chamber.