Medical Injection Device Ratchet Dosage Adjustment Mechanism

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Solution Overview

Problem

Existing medical injection devices are complex in structure, difficult to assemble, and costly to manufacture, with components requiring high machining precision, leading to issues like component sticking and wear, which can result in device failure and incorrect dosing.

Innovation Solution

A medical injection device with a simplified structure featuring a dial threaded rod and piston rod connected through a driving mechanism, utilizing a ratchet and adjustment key for dosage adjustment, and an elastic pressing member to ensure stable transmission and prevent misoperation, allowing for easy assembly and low manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If complex transmission mechanisms (clutch means, flexible arm, toothed member) are used to achieve dosage adjustment and injection, then the device can perform automated injection functions, but the structure becomes complicated and manufacturing cost increases

Engineering Contradiction:

Improveautomated injection functionVSAvoidstructure complexity

Core Design Contradiction:

Extent of automationVSDevice complexity

Solution Approach 1:

The patent extracts and removes the complex clutch means, flexible arm, and toothed member from the transmission mechanism. Instead, it uses a simple ratchet structure (teeth on piston rod engaging with pawls on driving member) to achieve the same automated injection function with significantly reduced structural complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs simple, easily manufacturable components such as the ratchet teeth directly formed on the piston rod and pawls on the driving member. These simple mechanical elements are easier and cheaper to manufacture compared to the complex clutch and flexible arm mechanisms, while still achieving reliable automated injection.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If multiple threaded connections and locking elements are used to ensure stable transmission, then the device achieves reliable dosage delivery, but the assembly difficulty and machining precision requirements increase

Engineering Contradiction:

Improvetransmission stabilityVSAvoidassembly difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges the dosage adjustment mechanism and injection transmission mechanism into a unified ratchet-based system. The teeth on the piston rod and pawls on the driving member serve dual purposes: they control dosage delivery and ensure stable transmission simultaneously, eliminating the need for separate threaded connections and locking elements.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Instead of using threaded connections to prevent rotation (as in prior art), the patent inverts the approach by using the ratchet teeth-pawl engagement to control both rotation and axial movement. The teeth are inclined to allow axial movement during injection while preventing reverse rotation, achieving stable transmission with simpler assembly.

Inventive Principle:

Principle #13The other way round (Inversion)

3Manufacturing precision

If precise threaded engagement between piston rod and driving member is used to prevent disconnection, then the device ensures accurate dosage delivery, but the machining precision requirements and manufacturing cost increase

Engineering Contradiction:

Improvethreaded engagement precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces precision-machined threaded engagement with a ratchet-based mechanical engagement system. The teeth on the piston rod and pawls on the driving member use simple geometric shapes that are easier and cheaper to manufacture, while still providing reliable connection and accurate dosage delivery through the ratchet mechanism's inherent mechanical advantage.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 device achieves easy operation, high dosage fineness, and safety with reduced manufacturing costs, preventing piston rod disconnection and ensuring accurate dosage delivery while maintaining transmission stability.

Implementation Method 1

a ratchet and adjustment key for dosage adjustment

Methodology Applied

Scientific EffectRatchet mechanism: Ratchet

Implementation Method 2

an elastic pressing member to ensure stable transmission

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 3

dial threaded rod and piston rod connected through a driving mechanism

Methodology Applied

Scientific EffectScrew mechanism: Screw

Data Source

PatentUS10617828B2Medical injection device

Publication Date: 2020.04.14 JIANXING SUMMED MEDTECH CO LTD

AI summary

A medical injection device, comprising: a housing having a first end cover and a second end cover provided at two ends thereof, respectively; a dial threaded rod, which is in threaded connected to the first end cover; and, a piston rod, which is used for expelling a dose, an upper end of the piston rod being connected to the dial threaded rod through a driving mechanism while a lower end thereof is in threaded connected to the second end cover. It further comprises a dosage adjustment mechanism, which is arranged between the dial threaded rod and the housing and used for driving the dial threaded rod to move in an axial direction of the housing.