Injection Device Gear Assembly Reduces Shield Removal Force
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Solution Overview
Problem
Existing injection devices require excessive force to remove the needle shield, making it difficult for elderly or infirm patients to access the needle for injection, which can lead to accidental needle exposure or failure to administer medication.
Innovation Solution
The injection device incorporates a gear assembly with a rotary and linear gear system, actuated by a lever arm, that reduces the force required to separate the needle shield from the body, allowing for controlled and easier removal of the shield, thereby facilitating patient use.
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 prior to injection
Solution Approach 1:
The cap assembly is segmented into two functional parts: the outer cap that remains on the body for retention, and the needle shield that can be independently removed. This segmentation allows the retention function and removal function to be decoupled, resolving the contradiction between secure attachment and easy removal.
Solution Approach 2:
The needle shield is extracted as a separate removable component from the cap assembly. The gear assembly and actuator mechanism extract the force requirement from the user's manual capability and transfer it to an automated mechanical system, allowing easy activation while maintaining secure retention.
2Ease of operation
If a gear assembly is added to reduce the force required to remove the needle shield, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The gear assembly acts as an intermediary mechanism between the user's simple rotational input and the linear extraction motion of the needle shield. This intermediary converts a easy-to-perform rotational motion into the required linear force, improving ease of operation while keeping the mechanism relatively simple through standard gear components.
Solution Approach 2:
The direct manual pulling motion is replaced with a rotational actuation system that uses mechanical advantage through gears. This substitution transforms a difficult linear pulling action into an easier rotational motion, leveraging mechanical principles to reduce user effort.
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 gear assembly significantly reduces the force needed to remove the needle shield, making it easier and safer for patients to access the needle, enhancing usability and reducing the risk of accidental needle exposure.
Implementation Method 1
a gear assembly comprising a first rotary gear and a first linear gear to engage with the first rotary gear, configured such that rotation of the first rotary gear drives the first linear gear to urge the needle shield away from the body
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
The present disclosure relates to an injection device. The injection device comprises a body for holding a syringe that has a needle at one end and a cap that is removably attached to the body. The cap has a needle shield to cover said needle. The injection device further comprises a gear assembly comprising a first rotary gear and a first linear gear to engage with the first rotary gear. The gear assembly is configured such that rotation of the first rotary gear drives the first linear gear to urge the needle shield away from the body. An actuator is provided that is configured to rotate the first rotary gear.