Auto-injector Needle Protection Sleeve Spring Mechanism
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Solution Overview
Problem
Existing auto-injectors are not cost-effective and reliable in operation, lacking efficient mechanisms for product dispensing and needle protection.
Innovation Solution
The auto-injector design incorporates a housing with a product container, a propulsion member, and a needle protection sleeve, utilizing springs for product dispensing and acoustic/tactile signaling, along with a syringe module that secures the product container axially, ensuring reliable operation and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a needle protection sleeve is provided that can be displaced into the housing to protect the needle, then user safety is improved, but the device complexity increases
Solution Approach 1:
The needle protection sleeve is merged with the housing structure, where the housing itself forms part of the protection mechanism. The sleeve is integrated into the housing and displaces relative to it, combining the protection function with the existing housing structure rather than adding a completely separate protection mechanism.
Solution Approach 2:
The housing serves multiple functions: it provides structural support, guides the needle protection sleeve movement, and participates in the needle protection mechanism. The spring element also serves dual purposes by providing both the displacement force and the locking mechanism through its interaction with the housing and sleeve.
2Reliability
If the needle protection sleeve is locked in the needle protection position, then reliability of needle protection is improved, but the device complexity increases
Solution Approach 1:
The locking mechanism is self-service in that the spring element automatically locks the needle protection sleeve in the protected position without requiring additional user action or complex control systems. The spring's inherent mechanical properties provide both the actuation force and the locking function, making the system self-regulating.
Solution Approach 2:
The patent replaces electronic or complex mechanical locking systems with a simple spring-based mechanical locking mechanism. The spring element interacts with the housing and needle protection sleeve through purely mechanical means, eliminating the need for motors, sensors, or complex control circuits while achieving reliable locking.
3Ease of operation
If a spring element is used to displace the needle protection sleeve, then the operation is simplified, but the manufacturing precision requirements increase
Solution Approach 1:
The spring element's parameters (force constant, preload, length) are optimized to provide sufficient displacement force while accommodating manufacturing tolerances. By carefully selecting the spring parameters, the design achieves reliable needle protection sleeve displacement without requiring extremely tight manufacturing tolerances on other components.
Solution Approach 2:
The spring element provides a cushioning effect by gradually displacing the needle protection sleeve rather than abrupt movement. This gradual action compensates for minor manufacturing variations and ensures smooth operation, reducing the impact of manufacturing precision limitations on overall system performance.
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 auto-injector effectively dispenses the product with precise control, provides reliable needle protection, and emits signaling cues, enhancing user safety and operational reliability while maintaining cost-effectiveness.
Implementation Method 1
The auto-injector has a spring element, in particular a compression spring, which is arranged in the housing and acts on the needle protection sleeve in the proximal direction, i.e. into the housing
Implementation Method 2
The signaling element (11) is designed to generate an acoustic and/or tactile signal in use by impacting against the signal stop (12b)
Data Source
Figure 1a
Figure 1b
Figure 2a~2c
AI summary
The invention relates to an auto-injector for outputting a liquid product, in particular a medicine, comprising: a) a housing (2) and a product container (13) arranged in the housing (2), in particular a syringe, having a moveable plunger (13b), wherein the plunger (13b) can be moved in an output direction in order to output the product contained in the product container (13); b) a driving element (7; 7') which acts on the plunger (13b) during the output of the product, and a first spring (9) which acts on the driving element (7; 7'); c) a needle protection sleeve (3) which can be shifted out of its starting position relative to the housing (2) and along a longitudinal axis (L) of the auto-injector in the proximal direction, in particular with an actuation stroke (HB), in order to trigger the product output, whereby a second spring (10) is tensioned and, in particular, the product output is triggered, wherein the needle protection sleeve (3) acts on the second spring (10); characterised in that, d) the housing (2) comprises a retaining section, wherein the retaining section of the housing projects in the distal direction over the distal end of the housing; and e) the driving element has an inwardly projecting rib (7c; 7c') or inwardly projecting ribs (7c; 7c') on an inner side, and the length of the rib (7c; 7c') or the ribs (7c; 7c') determines a pretensioning of the first spring (9) such that it can output the product from the product container (13b) by shifting the driving element (9) with an output stroke (HA).