Multi-Dose Dispenser With Serrated Plunger Latches for Precise Dosing
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Solution Overview
Problem
Existing multi-dose dispensers face challenges in providing precise dose control due to variations in hand pressure and transverse pressure causing skin damage, and existing mechanisms like levers and pawls are inefficient in controlling the injection process.
Innovation Solution
A multi-dose dispenser with an inner and outer housing system, a serrated plunger rod, and latches that limit movement to control dose dispensing, using advancing and retaining latches to ensure precise dose delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional cylindrical syringe with a rectilinear plunger is used, then the device structure is simple, but the dose control precision is very poor
Solution Approach 1:
The plunger rod is divided into multiple segments with alternating directions of serrations. Each segment can be independently controlled by corresponding latches, allowing precise segmentation of the total dose into multiple controllable increments. This segmentation enables the operator to control the plunger movement in small, precise steps rather than making large, imprecise adjustments.
Solution Approach 2:
The latches provide tactile feedback to the operator when the plunger reaches specific positions. The advancing latches engage with the serrated plunger rod to indicate when a dose has been administered, and the retaining latches provide feedback when the plunger needs to be reset. This feedback mechanism helps the operator precisely control the dosing process without relying on visual estimation or complex measurements.
2Measurement precision
If projections on the plunger are used to limit plunger travel, then some dose control is achieved, but excessive pressure is applied causing variable dose and skin damage
Solution Approach 1:
The latches are positioned at specific locations along the plunger rod to provide localized control at critical positions. The advancing latches are positioned to engage with the serrations at specific intervals, providing precise control at each dosing stage. This localized control allows the operator to apply pressure only when needed and release it when the dose is complete, preventing excessive continuous pressure that would cause skin damage.
Solution Approach 2:
The system transitions from a static plunger mechanism to a dynamic one where the latches can engage and disengage based on the dosing requirements. The advancing latches can be manually actuated to advance the plunger to the next dose position, and the retaining latches can be actuated to reset the plunger. This dynamic control allows the operator to adjust the pressure application in real-time based on the dosing progression, preventing excessive pressure while maintaining precise dose control.
3Measurement precision
If a lever with pawl mechanism is used, then plunger control is improved, but the mechanism becomes complex and inefficient
Solution Approach 1:
The invention extracts the essential control function from the complex lever-pawl mechanism and implements it through simpler latch-serration interactions. Instead of using a lever arm and pawl to control plunger movement, the system uses latches that directly engage with serrations on the plunger rod. This extraction of the core control function eliminates the unnecessary lever and pawl components, simplifying the mechanism while maintaining precise plunger control.
Solution Approach 2:
Instead of using a lever that moves the plunger through mechanical advantage, the system inverts the approach by using latches that directly engage with serrations on the plunger rod. The control mechanism is inverted from a indirect lever-based system to a direct latch-serration engagement system. This inversion simplifies the mechanism by eliminating the lever arm and pawl, while still providing precise control through the serrated plunger rod and corresponding latches.
4Productivity
If the plunger rod and plunger are advanced manually, then dose dispensing is possible, but hand position variation makes pressure control difficult
Solution Approach 1:
The serrated plunger rod and corresponding latches create a self-aligning mechanism that automatically maintains proper hand position and pressure distribution. As the latches engage with the serrations, they guide the hand position and ensure consistent pressure application without requiring the operator to manually adjust their hand position. The mechanism serves itself by using the serrated-slat engagement to maintain optimal injection geometry throughout the dosing process.
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3C
AI summary
A multi-dose injector comprising an inner housing (16) and an outer housing (12), the inner housing (16) being movable within the outer housing for a defined distance, a plunger rod (20) comprising a shaft (66) mounted within the inner housing, (16) the (66) shaft having a plurality of spaced apart teeth (68) formed thereon, an actuator (22) located at one end of the shaft (66), the inner housing (16) having at least one pawl (70) arranged to engage with the teeth (68), a syringe (74) mounted interiorly of the inner housing (16), the syringe being arranged such that the shaft engages with a plunger (76) within the syringe, and a spring member (18), the spring member (18) being biased between the inner housing (16) and the outer housing (12).