Injection Device Cap Lifting Mechanism for Low-Force Removal
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Solution Overview
Problem
Infirm patients, such as the elderly or physically impaired, face difficulty in removing the cap from injection devices due to high required forces, which are exacerbated by cold temperatures, leading to increased removal challenges.
Innovation Solution
An injection device with a lifting mechanism that converts rotational movement of the cap's outer member into axial movement of the inner member, reducing the force needed to remove the cap, featuring an axially-inclined portion and lifting portion to facilitate easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap is tightly attached to the housing to secure the needle shield, then the protection and reliability are improved, but the force required to remove the cap increases making it difficult for infirm patients
Solution Approach 1:
The lifting mechanism applies a preliminary assisting force in the distal direction before the user removes the cap. The axially-inclined portion and lifting portion work together to generate this counteracting force that opposes the frictional resistance, thereby reducing the net force the user must apply to remove the cap while maintaining secure attachment during storage and transport.
Solution Approach 2:
The lifting mechanism acts as an intermediary between the user's manual force and the cap-housing connection. By introducing this mechanical assistance system with the axially-inclined portion and lifting portion, the device mediates the force transmission, converting user input into effective removal motion while reducing the direct force requirement on the user.
2Reliability
If the cap is tightly attached to prevent accidental removal, then the reliability is improved, but the force required to remove the cap increases especially at cold temperatures
Solution Approach 1:
The lifting mechanism provides preliminary assistance by generating a distal-directed force that counteracts the increased frictional resistance caused by cold temperatures. The axially-inclined portion and lifting portion work together to reduce the net removal force required, making the device operable in cold storage conditions while maintaining secure attachment during storage.
3Device complexity
If a simple cap structure is used, then the device complexity is reduced, but the ability to assist in cap removal is limited
Solution Approach 1:
The lifting mechanism is implemented using nested components where the lifting portion is disposed within the cap structure and the axially-inclined portion is integrated into the housing or cap assembly. This nested arrangement allows the assistance mechanism to be contained within the overall cap structure without significantly increasing external complexity or size.
Solution Approach 2:
The lifting mechanism introduces a rotational dimension to the removal process. Instead of purely axial extraction, the axially-inclined portion converts rotational motion of the cap relative to the housing into axial lifting motion, adding a dimensional aspect to the removal operation that provides mechanical advantage.
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 lifting mechanism assists users in removing the cap with less force, especially beneficial for infirm patients, by converting rotational motion into axial motion, thus simplifying the process and reducing the impact of cold temperatures.
Implementation Method 1
a lifting mechanism configured to reduce a force required to remove the cap and an engaged needle shield from the housing, the lifting mechanism comprising at least one axially-inclined portion in engagement with at least one lifting portion such that rotational movement of the outer member or intermediate member is converted into an axial movement of the inner member
Data Source
AI summary
An injection device comprising a housing and a cap at a distal end of the housing, the cap comprising: an outer member; an intermediate member disposed within the outer member, at least one of the intermediate member or outer member being rotatable relative to the other of the intermediate member or outer member; and, an inner member disposed within the intermediate member, and coupled to at least one of the outer member and the intermediate member, the inner member being configured to engage a needle shield in the housing. The injection device further comprises a lifting mechanism to reduce a force required to remove the cap from the housing, the lifting mechanism comprising at least one axially-inclined portion in engagement with at least one lifting portion such that rotational movement of the outer member or intermediate member is converted into an axial movement of the inner member from the housing.