Radially Movable Locking Element for Needle Shield
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Solution Overview
Problem
Existing needle protection systems for injection devices require high spring forces to overcome deflecting members, leading to deformation of plastic parts, inaccurate injections, and risks of liquid spilling, while also being cumbersome and expensive to manufacture.
Innovation Solution
A needle protection assembly with a low-duty urging mechanism, such as a helical spring, that moves the needle shield from the 'in use' to the 'after use' position without direct contact with the needle, using a radially movable locking element that becomes non-coaxial to lock the shield in place, reducing the force required and preventing liquid spilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high spring force is used to overcome deflecting members, then the needle shield can be reliably locked in after-use position, but plastic parts deform and injection accuracy deteriorates
Solution Approach 1:
The patent removes the deflecting members from the locking mechanism, extracting the source of resistance that required high spring forces. The locking element directly engages with the needle shield without needing to deflect any members, eliminating the harmful high forces while maintaining reliable locking.
Solution Approach 2:
The locking element acts as an intermediary between the spring and the needle shield. Instead of the spring directly overcoming deflecting members, the locking element mediates the force transmission, allowing the spring to operate at low duty while still achieving reliable locking through the radial movement mechanism.
2Reliability
If high spring force is used to overcome deflecting members, then the needle shield can be reliably locked in after-use position, but the device becomes cumbersome and expensive to manufacture
Solution Approach 1:
The patent extracts the deflecting members from the system, eliminating the need for high-duty springs and complex assembly procedures. This simplification reduces manufacturing complexity and cost while maintaining locking reliability through the direct engagement mechanism.
Solution Approach 2:
The patent changes the force parameter of the spring from high duty to low duty by fundamentally altering the locking mechanism. The locking element's radial movement capability allows the same locking function to be achieved with significantly reduced spring force, simplifying the overall device.
3Ease of operation
If locking element is in direct contact with needle, then the needle shield can be triggered to after-use position, but liquid spilling risk increases
Solution Approach 1:
The patent extracts the locking element from direct contact with the needle, eliminating the source of liquid spilling. The locking element instead contacts the needle shield's lateral surface, maintaining triggering capability while preventing contamination risks associated with needle contact.
4Reliability
If deflecting members are used in locking system, then the needle shield can be locked in after-use position, but the spring force required increases
Solution Approach 1:
The patent removes the deflecting members from the locking system, eliminating the resistance they create. This allows the spring to operate at low duty while the locking element achieves reliable locking through radial movement and direct engagement with the needle shield.
Solution Approach 2:
Instead of the spring forcing the needle shield to overcome deflecting members, the invention inverts the mechanism: the locking element radially moves to engage the needle shield laterally. This inversion eliminates the need for high forces while maintaining the locking function.
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 solution prevents deformation of plastic parts, ensures accurate and reliable injections, and is easier to manufacture with fewer and less expensive components, while minimizing the risk of liquid spilling and accidental needle stick injuries.
Implementation Method 1
urging means, such as a helical spring, that moves the needle shield from the 'in use' to the 'after use' position
Data Source
AI summary
The application relates to needle protection assembly (1)) comprising:—a support (2) of the needle (3),—a needle shield (8) having a longitudinal axis A,—urging means (13) for displacing said needle shield (8) from a “in, use” position to a “after use” position,—a locking element (10) intended to prevent said needle shield (8) from moving back from its “after use” position to its “in use” position, characterized in that said locking element (10) has a longitudinal axis B and is radially movable with respect to said needle shield (8) between a “free” position, in which the longitudinal axis A of the needle shield (8) and the longitudinal axis B of the locking element (10) are merged and in which said needle shield (8) is movable from its “in use” position to its “after use” position, and a “locking position”, in which the longitudinal axis B is radially spaced apart from the longitudinal axis A and in which movement of the needle shield (8) from its “after use” position to its “in use” position is prevented.