Injection Device Cap Cam Mechanism for Boot Removal
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Solution Overview
Problem
Existing injection devices require substantial force to remove the hermetically sealed boot from the syringe, posing difficulties for patients with rheumatoid arthritis, the elderly, or those with limited manual dexterity, as the boot is small and fiddly, and often positioned inside the device, limiting access.
Innovation Solution
An injection device with a housing and closure member featuring camming surfaces and a castellated grip washer that deforms to securely hold the boot, allowing easy removal by rotating the closure member, which reduces the force needed to remove the boot and provides a secure grip for users.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the boot is hermetically sealed to maintain sterility, then sterility is improved, but the force required to remove the boot increases
Solution Approach 1:
The invention separates the boot removal function from the syringe itself by introducing a dedicated cap with connection means. The cap acts as an intermediary component that the user grips and rotates to remove the boot, dividing the difficult removal action into a manageable operation on the cap rather than directly on the boot.
Solution Approach 2:
The cap serves as an intermediary tool between the user and the boot. The connection means on the cap engages with the boot to provide a secure grip, allowing the user to apply rotational force to the cap which then translates to boot removal without requiring the user to directly grip the small, difficult-to-grasp boot.
2Reliability
If the boot is positioned inside the housing for sterility, then sterility is improved, but the ease of operation deteriorates
Solution Approach 1:
The boot is pre-positioned inside the housing with its open end facing the first end of the housing, and the cap is designed with connection means that will engage with the boot. This preliminary arrangement ensures that when the user rotates the cap, the connection means is already in position to grip and remove the boot, streamlining the operation.
3Volume of moving object
If the boot is made small to fit the syringe, then the device compactness is improved, but the ease of operation deteriorates
Solution Approach 1:
The cap with its connection means acts as a force multiplier and grip enhancer. Instead of requiring the user to directly grip the small boot, the connection means on the cap provides a larger, more accessible gripping surface that engages with the boot, making removal feasible even though the boot itself remains small.
4Ease of operation
If a grip feature is added to the cap, then the ease of operation is improved, but the device complexity increases
Solution Approach 1:
The cap serves multiple functions: it covers the discharge nozzle to maintain sterility, provides a gripping surface for user operation, and incorporates connection means to engage with and remove the boot. By combining these functions into a single component, the invention avoids adding separate mechanisms for each function, thereby limiting the increase in 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 solution significantly reduces the force required to remove the boot, making it accessible for users with limited dexterity and maintaining sterility, while allowing standard syringe use without modification, minimizing manufacturing costs and operational steps.
Implementation Method 1
the housing defining a first axis and having first and second ends... the housing further having a camming surface at its first end; and a housing closure member having a camming surface for communicating with the camming surface on the housing so that rotation of the housing closure member about the axis causes the housing closure member to move axially away from the housing
Implementation Method 2
The means for connecting may comprise a pressed grip washer with a profiled internal diameter. In use, the boot would be inserted into the centre of the grip washer, and the profiled internal diameter would deform slightly to surround the boot. In particular, the grip washer may be bent into a frustoconical shape. However, as the cap is removed, the grip washer would dig into the boot and prevent it from being removed from the cap.
Data Source
AI summary
An injection device (110) is described having a housing (112) and a cap (130). The injection device (110) houses a syringe (114) having a needle (118) which is sealed by a boot (120). The cap (130) is arranged so that the boot (120) can be connected to the cap (130) simply, but cannot be removed from the cap (130). The housing (112) and cap (130) are arranged so that upon rotation of the cap (130), the cap (130) is moved axially away from the housing (112) and the boot (120) is removed from the syringe (114). The injection device is simple to use and manufacture.