Injection Dose Mechanism with Ratchet Click Feedback
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Solution Overview
Problem
Existing injection devices require high user force for dose dispensing and lack effective user feedback mechanisms in a compact design.
Innovation Solution
A manually driven injection device with a ratchet member that includes distinct counter dosing and dispensing click teeth, allowing for reduced friction through threaded plunger rod movement and providing audible and tactile feedback, while maintaining a space-saving design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a manually driven injection device uses a ratchet member with distinct counter dosing and dispensing click teeth, then user force required for dose dispensing is reduced, but device complexity increases
Solution Approach 1:
The ratchet member is segmented into distinct counter dosing click teeth and counter dispensing click teeth, which are spatially separated and functionally independent. This segmentation allows the mechanism to reduce friction during dispensing while maintaining dosing accuracy, resolving the contradiction between reducing user force and maintaining device simplicity.
Solution Approach 2:
The mechanism dynamically transitions between dosing mode and dispensing mode through the relative movement of the drive member and ratchet member. During dispensing, the threaded connection enables rotational movement that reduces friction; during dosing, the ratchet teeth engage to provide feedback. This dynamic behavior allows the system to optimize performance for each function without permanently increasing complexity.
2Loss of information
If the injection device provides audible and tactile feedback through click teeth engagement, then user feedback is enhanced, but device complexity increases
Solution Approach 1:
The ratchet member incorporates click teeth that engage with corresponding teeth on the drive member to produce audible and tactile feedback during both dosing and dispensing operations. This feedback mechanism provides real-time information to the user about the device state without requiring additional electronic components, thus enhancing user feedback while maintaining mechanical simplicity.
Solution Approach 2:
The feedback function is merged into the primary mechanical components (ratchet member and drive member) rather than being a separate system. The click teeth serve dual purposes: transmitting mechanical motion and providing user feedback, thereby enhancing information delivery without proportionally increasing device complexity.
3Ease of operation
If the plunger rod moves through threaded connection to reduce friction, then ease of operation is improved, but device complexity increases
Solution Approach 1:
The linear reciprocating motion of the plunger rod is replaced with rotational motion through a threaded connection. This substitution reduces friction during the dispensing phase by converting the high-friction linear sliding motion into lower-friction rotational motion, thereby improving ease of operation while integrating the mechanism into the existing ratchet-driven system.
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
Reduces the user force required for dose dispensing and provides clear feedback through clicks, enhancing user experience and efficiency in a compact mechanism.
Implementation Method 1
plunger rod which is in a threaded connection with the housing and is thus screwed in dispensing direction
Implementation Method 2
ratchet teeth slide over saw teeth of the housing thereby generating a click sound
Data Source
Figure 1~2
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Figure 5~7
AI summary
The invention relates to dose and dispensing mechanism comprising a housing (10), a plunger rod (60), a dosing click member (80) comprising axially extending dosing click teeth (82) adapted to engage axially extending counter dosing click teeth (72) and the mechanism further comprises a dispensing click member (90) inside the housing and comprising dispensing click teeth (91) adapted to engage counter dispensing click teeth (71). In a dose setting position the drive member (40) is operatively coupled to the dosing click member (80) to rotate it relative to the housing which causes the dosing click teeth (82) to slide over the counter dosing click teeth (72) and in a dispensing position the drive member (40) is operatively coupled to the dispensing click member (90) to rotate it relative to the housing which causes the dispensing click teeth (91) to slide over the counter dispensing click teeth (71).