Syringe Cannula Positioning via Inclined Slide Tracks
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Solution Overview
Problem
Existing syringe designs face issues such as high manufacturing costs, high reject rates, and safety concerns due to complex mechanisms, which can lead to unintended disconnection of the cannula and potential needlestick injuries, as well as compromised sterility and purity of the medicine during administration.
Innovation Solution
The syringe design incorporates a pinion with guide knobs that engage with inclined slide tracks, a locking device to secure the cannula in place, and a plunger system with a coupling extension and locking elements to ensure secure and safe operation, preventing cannula movement and ensuring sterility and purity of the medicine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a guide pin is arranged on the inside of the cannula support guide to enable rotational guidance, then the cannula can be guided into position, but the manufacturing cost increases and reject rates become high
Solution Approach 1:
The guide pin is extracted from the interior of the cannula support guide and relocated to the exterior surface. This allows the guide pin to fulfill its positioning function while eliminating the complex internal machining requirements, thereby reducing manufacturing costs and reject rates.
Solution Approach 2:
Instead of placing the guide pin inside the guide structure, the invention inverts the arrangement by positioning it on the outside. This external placement achieves the same guiding function through a simpler, more manufacturable design.
2Ease of operation
If the cannula support is freely guided to allow rotational movement, then ease of assembly is improved, but unintended disconnection occurs compromising safety
Solution Approach 1:
The guide pin is pre-positioned on the guide sleeve at a specific location that ensures the cannula support will naturally engage and lock into the correct position during assembly. This preliminary positioning prevents unintended disconnection while maintaining ease of assembly.
Solution Approach 2:
The design employs a simple, disposable cannula support structure with an integrated guide pin that ensures single-use safety. The guide pin's fixed position on the guide sleeve creates a reliable one-time engagement that prevents reuse, aligning with disposable medical device safety requirements.
3Reliability
If the cannula is rotated into the sealing disc during piercing, then connection is achieved, but abrasion particles are formed contaminating the medicine
Solution Approach 1:
Instead of rotating the cannula into the sealing disc, the invention inverts the approach by having the cannula move linearly along an inclined path guided by the guide pin. This eliminates rotational friction and abrasion that would generate particles contaminating the medicine.
Solution Approach 2:
The guide pin on the guide sleeve acts as an intermediary that directs the cannula's movement along a controlled inclined path. This intermediary guidance mechanism ensures smooth, particle-free insertion into the sealing disc while maintaining reliable connection.
4Reliability
If a complex mechanism with multiple components is used to secure the cannula, then connection security is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The guide pin is merged directly into the guide sleeve structure, eliminating the need for separate, complex guiding mechanisms. This integration maintains cannula connection security while significantly reducing device complexity and manufacturing requirements.
Solution Approach 2:
The guide pin on the guide sleeve serves multiple functions simultaneously: it guides the cannula's linear movement, ensures proper positioning, prevents rotation, and enables secure engagement with the sealing disc. This multi-functionality reduces the need for additional components.
Data Source
AI summary
The invention relates to a syringe (20) comprising a syringe barrel (15), an ejector unit (25) arranged at the distal end of the syringe barrel (15) with a plunger rod (17), a coupling part (37) and a plunger (16) and a syringe head (21) arranged at the proximal end of the syringe barrel (15) with a needle unit (12) which is arranged in a guide sleeve (5) and is slidable therein with a cannula (3) and a cannula holder (4) and a pinion (2), by means of which the needle unit (12) is axially movable, relative to a syringe barrel (15) from a rest position to an actuation position. At the distal end of the guide sleeve (5) a sealing element (7) is arranged. The pinion (2) has at least one guide knob (1), which can be brought into engagement optionally with one of two slide tracks (10) provided in the guide sleeve (5), wherein the slide tracks (10) are inclined in opposite directions.