Nested Plunger Assembly for Compact Drug Delivery
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Solution Overview
Problem
Conventional chemical solution administration devices are not effectively downsized, limiting their applicability and usability due to the limited movement of a single plunger mechanism, which restricts the device's size reduction and usability when applied to a patient's body.
Innovation Solution
A plunger assembly with an extendable design that includes a feed screw, multiple plungers, and a nut member, allowing for multi-stage extension to reduce the overall length, enabling reliable forward movement of the plungers and efficient chemical solution administration, while minimizing device size and enhancing usability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a single plunger mechanism is used, then the device structure is simple, but the device size cannot be effectively reduced
Solution Approach 1:
The patent implements a nested plunger structure where a first plunger is disposed inside a second plunger, and both are inserted into a chemical solution container. The feed screw passes through both plungers, creating a compact nested arrangement that significantly reduces the overall device length while maintaining the thread engagement mechanism for reliable plunger movement.
Solution Approach 2:
The plunger mechanism is segmented into multiple independent plungers (first plunger and second plunger) that can move relative to each other. Each plunger has its own female thread portion that engages with the male thread portion of the feed screw, allowing the system to achieve compact size through segmented, modular design while preserving functional reliability.
2Length of moving object
If multiple plungers are used to reduce device size, then the device can be downsized, but the mechanism complexity increases
Solution Approach 1:
The feed screw serves multiple functions simultaneously: it provides the threading engagement mechanism for both plungers, acts as the driving element for moving both plungers forward, and functions as the structural backbone connecting all components. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in mechanism complexity despite using multiple plungers.
Solution Approach 2:
The patent merges the driving mechanism for multiple plungers into a single feed screw component. Both the first and second plungers engage with the same feed screw through their respective female thread portions, combining what could have been separate driving mechanisms into one unified structure, thus reducing overall complexity while achieving compact size.
3Adaptability or versatility
If the nut member is fixed, then the thread engagement is stable, but the device loses adaptability in engagement timing
Solution Approach 1:
The nut member is designed to move axially relative to the feed screw rather than being fixed in position. This dynamic arrangement allows the nut member to adjust its position along the feed screw, enabling the system to accommodate variations in engagement timing while maintaining stable thread engagement through the movable connection.
Solution Approach 2:
The nut member acts as an intermediary element between the feed screw and the plungers. By allowing axial movement, it mediates the timing and positioning of thread engagement, providing adaptability in when the engagement occurs while ensuring that the engagement itself remains stable and reliable once established.
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 downsized device reduces the required application area, improves usability, and ensures reliable forward movement of the plungers, facilitating easier application and storage, with the nut member's axial movement ensuring consistent thread engagement for smooth operation.
Implementation Method 1
a feed screw (48) including a rod portion (58), the rod portion including a male thread portion (62) having a male thread (62a) formed thereon
Implementation Method 2
a first female thread portion (68a) threadedly engaged with the male thread portion (62) of the feed screw (48) at least in an initial state
Data Source
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AI summary
A plunger assembly (14A) of a chemical solution administration device (10) includes a feed screw (48) including a male thread portion (62) and an extending portion (63), a first plunger (50) including a first female thread portion (68a), a second plunger (52) including a nut accommodating portion (88), a nut member (54) including a second female thread portion (54a), and a base portion (56) that guides the second plunger (52). A nut accommodating portion (88) accommodates the nut member (54) so that the nut member (54) is non-rotatable and movable in the axial direction.