Injection Device Cam Mechanism Prevents Premature Activation
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Solution Overview
Problem
Existing automatic and semi-automatic injection devices for mixing and delivering medicament agents with diluents face issues such as high mixing forces degrading the medicament, reliance on batteries leading to malfunctions, complex designs, and user-unfriendly interfaces, which compromise safety and dose accuracy.
Innovation Solution
An injection device with a dual-housing mechanism featuring a plunger rod, flexible locking means, and a locking member that ensures the mixing process is complete before automatic injection, preventing premature activation through a hook mechanism and compression spring, allowing for safe and accurate delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If automatic mixing is performed using springs and mechanical means, then the mixing process is automated, but the mixing force is too high at the beginning causing medicament degradation
Solution Approach 1:
The patent employs a cam mechanism that transforms the static spring force into a dynamic mixing process. The cam profile is designed to vary the mixing force over time, starting with lower force and gradually increasing it, thereby avoiding initial high-force damage to the medicament while still achieving effective mixing through the dynamic motion pattern.
Solution Approach 2:
The invention changes the mixing force parameter over time through the cam mechanism. Instead of applying constant high force from the spring, the cam converts this into a varying force profile where the mixing force starts low and increases gradually, optimizing both the automation benefit and the medicament stability requirement.
2Extent of automation
If electronic control means are used for mixing and injection, then automated control is achieved, but the device becomes sensitive to noise, moisture, and battery dependency
Solution Approach 1:
The patent replaces the electronic control system with a purely mechanical cam-based control mechanism. The cam profile mechanically dictates the mixing and injection timing without requiring batteries, sensors, or electronic circuits, thereby eliminating sensitivity to noise, moisture, and battery failure while maintaining automated control functionality.
3Ease of operation
If manual mixing is performed with eye observation, then the user can monitor the mixing process, but the mixing force can be high if the user is stressed causing medicament degradation
Solution Approach 1:
The device enables self-regulating mixing through the cam mechanism. Once the user loads the cartridge and activates the device, the cam automatically controls the mixing force profile without requiring the user to continuously monitor or adjust the process. This eliminates the problem of stressed users applying excessive force while still allowing simple manual activation.
4Reliability
If locking means are added to prevent premature activation, then safety is improved, but the device complexity increases
Solution Approach 1:
The patent combines the locking function with the existing cam mechanism. The cam structure serves dual purposes: controlling the mixing/injection timing and preventing premature activation through its geometric constraints. This integration avoids adding separate locking components, thereby improving safety without significantly increasing device complexity.
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 ensures uncomplicated, safe, and accurate delivery of medicaments by preventing premature activation and ensuring complete mixing, reducing the risk of medicament degradation and improving user-friendliness while simplifying manufacturing and assembly.
Implementation Method 1
a compression spring arranged surrounding the locking member, between the radially holding means and a second annular part of the holding member
Implementation Method 2
flexible locking means releasibly connected to said plunger rod for holding said plunger rod and thereby said drive force means in a pre-tensioned state
Data Source
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AI summary
The present invention relates to an injection device for manually penetrating a needle arranged to said device and automatic injecting a medicament mixture, the device being of the type comprising: a first housing part into which a multi- chamber container is arranged and a second housing part which can be displaced relative to said first housing in order to mix at least two substances arranged inside said container; a plunger rod arranged to act on said container, drive force means capable of pushing said plunger rod for acting on said container, an activation member comprising flexible locking means releasibly connected to said plunger rod for holding said plunger rod and thereby said drive force means in a pre- tensioned state, and a push button protruding from said second housing part; and a locking member being arranged around said activation member and being axially slidable in relation to said activation member between a first position wherein said locking member completely surrounds said locking means and a second position wherein said locking member partially surrounds said locking means after said locking member has been axially displaced by said first housing when said first housing has been displaced into said second housing part; and wherein said flexible locking means are arranged to be released from said plunger rod only after said locking member is moved from the first position to the second position and said push button is axially moved into the second housing part, such that the flexible locking means comes completely out of contact with the locking member.