Gear Assembly for Needle Shield Removal Mechanism
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Solution Overview
Problem
Existing injection devices require excessive force to remove the cap, making it difficult for elderly or infirm patients to access the needle for medicament dispensing, which can lead to accidental needle exposure and injury.
Innovation Solution
The injection device incorporates a gear assembly with a double gear mechanism and an actuator that reduces the force required to separate the needle shield from the housing, allowing for controlled and easier removal, particularly designed for patient-friendly operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap is held onto the body with sufficient force to prevent accidental removal, then the needle is kept sterile and injury is prevented, but it becomes difficult for patients to intentionally remove the cap
Solution Approach 1:
The cap assembly is segmented into two functional parts: an outer cap that remains on the body and an inner needle shield that can be independently removed. This segmentation allows the retention force to be applied differently to each part, enabling secure attachment while facilitating controlled removal of the needle shield through the gear mechanism.
Solution Approach 2:
The gear assembly acts as an intermediary mechanism between the user's manual input and the needle shield removal process. It translates small manual movements into controlled separation of the needle shield, providing mechanical advantage to overcome the retention force without requiring excessive manual strength.
2Strength
If excessive force is required to remove the cap, then the cap remains securely attached during transport and storage, but elderly or infirm patients cannot easily remove it
Solution Approach 1:
The gear assembly serves as a mechanical intermediary that provides force multiplication. It converts the patient's limited manual force into sufficient separation force through gear ratio mechanics, enabling elderly or infirm patients to remove the needle shield without requiring excessive strength.
Solution Approach 2:
The system transitions from a static high-strength attachment (suitable for transport) to a dynamically controllable separation process (suitable for patient operation). The gear mechanism enables controlled dynamic separation while maintaining static attachment strength during storage and transport.
3Ease of operation
If the cap removal mechanism is simplified for patient use, then ease of operation improves, but control over the separation process may be reduced
Solution Approach 1:
The gear assembly acts as a controlled intermediary mechanism that provides both force reduction and motion control. It translates simple manual actuation into controlled separation of the needle shield, offering mechanical advantage while maintaining patient-friendly operation through intuitive sliding or pressing motions.
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 solution simplifies the cap removal process, reducing the force needed by translating the actuator's movement into a larger force on the needle shield, making it easier and safer for patients to use, especially those who are elderly or infirm.
Implementation Method 1
a gear assembly comprising first and second linear gears and a double gear, wherein the gear assembly is configured such that movement of the first linear gear in a first direction rotates the double gear to drive the second linear gear to urge the needle shield away from the housing
Implementation Method 2
The gear assembly and actuator may be configured to reduce the force that must be exerted by the patient to urge the needle shield away from the body
Data Source
AI summary
An injection device comprises a housing for holding a syringe that has a needle at one end and (ii) a cap that is removably attached to the housing and that has a needle shield to cover said needle. The cap further comprises an actuator and a gear assembly comprising first and second linear gears and a double gear. The gear assembly is configured such that movement of the first linear gear in a first direction rotates the double gear to drive the second linear gear to urge the needle shield away from the housing. The actuator is configured to move the first linear gear in the first direction.