Prefilled Injection Pen Ratchet Locking Mechanism
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Solution Overview
Problem
Users of existing insulin injection pens cannot precisely determine if the liquid medication has been completely injected, leading to uncertainty about the completion of the injection process.
Innovation Solution
The prefilled injection pen incorporates a screw rod, memory connection barrel, fixed barrel, and rotating barrel with one-way teeth and a ratchet pawl, allowing for scale adjustment and preventing further rotation when the medication is depleted, indicating the end of the liquid supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the clutch tube position is adjusted to change the scale value after injection is completed, then the scale value can still be adjusted, but the user cannot perform injection and cannot precisely know whether the injection is completed
Solution Approach 1:
The patent implements a dynamic locking mechanism where the ratchet pawl can engage with or disengage from the one-way teeth on the rotating barrel based on the plunger position. When the plunger reaches the bottom of the liquid medication tube, the ratchet pawl automatically engages with the one-way teeth to lock the rotating barrel, preventing further rotation and indicating injection completion. This dynamic state change resolves the contradiction by allowing scale adjustment during injection while providing a clear stop signal when injection is complete.
Solution Approach 2:
The patent incorporates a mechanical feedback mechanism through the ratchet pawl and one-way teeth interaction. As the plunger moves and reaches the bottom of the liquid medication tube, this mechanical feedback triggers the ratchet pawl to engage with the one-way teeth, providing immediate tactile and visual feedback to the user that injection is complete. This feedback loop resolves the uncertainty about injection completion while maintaining the ability to adjust scales during the injection process.
2Adaptability or versatility
If the user continues to rotate the rotating barrel after injection completion, then scale adjustment is possible, but the liquid medication is already depleted leading to uncertainty
Solution Approach 1:
The patent applies preliminary anti-action by pre-configuring the ratchet pawl mechanism to automatically engage with the one-way teeth when the plunger reaches the bottom of the liquid medication tube. This preventive mechanism stops the rotating barrel from rotating further after injection completion, thereby preventing the loss of injection status information. The mechanism proactively counteracts the potential harmful action of continuing to rotate the barrel after injection is complete.
Solution Approach 2:
The patent implements preliminary action by designing the ratchet pawl to be positioned and ready to engage with the one-way teeth before injection completion occurs. When the plunger approaches the bottom of the liquid medication tube, the mechanism is already in position to lock the rotating barrel, ensuring that the injection completion point is clearly marked before the user can mistakenly continue rotating. This preliminary preparation prevents information loss about injection status.
3Reliability
If the ratchet pawl engages with the one-way teeth to prevent rotation, then injection completion is indicated, but the device complexity increases
Solution Approach 1:
The patent applies the self-service principle by designing the ratchet pawl mechanism to automatically engage with or disengage from the one-way teeth based on the plunger position, without requiring external control or additional actuators. The mechanical interaction between the plunger, ratchet pawl, and one-way teeth creates a self-regulating system that indicates injection completion through the natural movement of components during the injection process, thereby achieving reliable detection with minimal added complexity.
Solution Approach 2:
The patent merges the injection mechanism with the completion indication mechanism by integrating the ratchet pawl and one-way teeth into the existing injection structure. The same rotating barrel that controls dosage also interacts with the ratchet pawl to provide completion indication, combining two functions into a unified mechanical system. This integration reduces overall device complexity compared to having separate independent systems for dosage control and completion detection.
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
Ensures users can accurately determine when the medication is depleted, preventing over-rotation and ensuring precise dosage delivery.
Implementation Method 1
a screw rod, a memory connection barrel, a fixed barrel, and a rotating barrel; on an end face of one end of the rotating barrel, a plurality of first one-way teeth are circumferentially provided
Implementation Method 2
an end face of one end of the fixed barrel is provided with a ratchet pawl cooperating with the first one-way teeth
Data Source
AI summary
A prefilled injection pen for injecting insulin, the prefilled injection pen including: a screw rod, a memory connection barrel, a fixed barrel and a rotating barrel. A plurality of first one-way teeth is evenly distributed on an end surface of the rotating barrel. The memory connection barrel is disposed inside the rotating barrel. The inner wall of the memory connection barrel is provided with a protrusion matching a thread of the screw rod. An end face of one end of the fixed barrel is provided with a ratchet pawl matching the first one-way teeth. The fixed barrel is also provided with a first inner thread matching the screw rod. The screw rod is provided with two machined plane surfaces. A plunger is disposed at one end of the screw rod and a stopper is disposed in a thread groove at the other end of the screw rod.