Medicament Dose Setting Mechanism with Threaded Limiting and Lock Member
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Solution Overview
Problem
Existing medicament delivery devices face challenges in ensuring safe and accurate dose setting, particularly for self-administration by untrained users, as they often allow for incorrect dose sizes or require complex mechanisms to prevent overdose, especially for children.
Innovation Solution
A dose setting mechanism featuring an elongated tubular distal housing with threads and indicia, a dose limiting member with protrusions, and a removable lock member, allowing for precise dose setting and locking to prevent exceeding the prescribed dose, enabling more than 360° rotation for dose setting and ensuring the dose cannot be increased beyond the preset value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a dose stop is arranged to prevent rotation beyond a single turn, then the device is simpler to manufacture, but the dose setting range is limited to one full rotation
Solution Approach 1:
The dose setting mechanism is divided into two functional segments: a dose limiting member with protrusions that sets the maximum dose, and a dose setting member with a knob that allows multiple rotations. The thread engagement between these segments enables the limiting member to control the range while the setting member provides extended rotation capability for precise dose selection.
Solution Approach 2:
The thread structure acts as an intermediary mechanism that translates rotational motion into axial movement. By engaging the threaded surfaces of the dose limiting member and dose setting member, the system converts multiple rotations of the knob into controlled linear displacement, enabling extended dose setting range while maintaining manufacturing simplicity.
2Adaptability or versatility
If a removable lock member is used to lock the dose limiting member, then the device allows for dose adjustment, but the device complexity increases
Solution Approach 1:
The dose limiting member is pre-configured with protrusions at specific positions that correspond to maximum dose limits. The removable lock member is designed to engage with these pre-positioned protrusions, locking the dose setting at the predetermined maximum value. This preliminary configuration simplifies the locking mechanism while maintaining dose adjustability.
Solution Approach 2:
The lock member transitions from a static to a dynamic state during operation. It is removed to allow the dose limiting member to be rotated and repositioned, then reattached to lock the new dose setting. This dynamic approach enables dose adjustment without requiring a complex continuously adjustable locking mechanism.
3Adaptability or versatility
If the dose setting mechanism allows more than 360° rotation, then the dose setting range is improved, but it becomes difficult to arrange a dose stop
Solution Approach 1:
The dose stop function is implemented not in the rotational dimension but in the axial dimension. As the dose setting member rotates more than 360°, the threaded engagement converts this rotational motion into axial movement. The dose limiting member's protrusions engage with the threads to stop axial movement at the predetermined dose limit, effectively placing the dose stop in a different dimensional space.
Solution Approach 2:
The traditional mechanical dose stop that directly blocks rotation is replaced with a threaded mechanical system. The thread structure substitutes for a direct rotational stop, allowing multiple rotations while converting the stopping mechanism to act on axial position rather than rotational position, thereby enabling extended dose setting range.
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 mechanism ensures that only the prescribed dose can be administered, providing safety and ease of use by preventing accidental overdose and allowing for dose setting beyond a single turn, thus enhancing user safety and reliability.
Implementation Method 1
said dose limiting member comprises a first thread segment on its outer circumference surface at its proximal end intended to cooperate with corresponding threads on the inner surface of the distal housing
Implementation Method 2
said dose setting member is coaxially arranged inside the dose limiting member and comprises a second thread segment having and end surface on its outer circumferential surface at its proximal end intended to cooperate with the threads of the distal housing
Implementation Method 3
said lock member comprises at least one elongated rib on its inner circumferential surface which is intended to interact with the protrusions of the dose limiting member for locking the dose limiting member in a certain position
Implementation Method 4
a stop surface at its proximal end... the end surface of the dose setting member abuts the stop surface of the dose limiting member, thereby preventing further movement of the dose setting member
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
The present invention relates to a dose setting mechanism intended to be used in a medicament delivery device, comprising an elongated tubular distal housing (16) having opposite distal and proximal ends, wherein said distal housing comprises threads (14) on its inner surface, a first window (30), a second window (32), and at least one opening (38) on its elongated surface; a tubular dose limiting member (10) having opposite distal and proximal ends, wherein said dose limiting member comprises a first thread segment (12) on its outer circumference surface at its proximal end intended to cooperate with corresponding threads on the inner surface of the distal housing, first indicia (18) on its outer circumferential surface, a stop surface (42) at its proximal end, and a number of protrusions (20) arranged equidistant to each other along the circumference on the outer surface at its distal end; a tubular dose setting member (22) having opposite distal and proximal ends, wherein said distal housing is coaxially arranged inside the dose limiting member and comprises a second thread segment (24) having and end surface (44) on its outer circumferential surface at its proximal end intended to cooperate with the threads of the distal housing, second indicia (26) on its outer circumferential, and a dose setting knob (28) protruding through the distal end of the distal housing; and a removable lock member (36) attached to the distal housing, wherein said lock member comprises at least one elongated rib (40) on its inner circumferential surface which is intended to interact with the protrusions of the dose limiting member for locking the dose limiting member in a certain position when the lock member is attached to the distal housing.