Syringe Friction Spring Mechanism for Controlled Suck-Back
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Solution Overview
Problem
Existing syringes for dispensing flowable and pasty materials, particularly in the dental field, suffer from post-use material leakage and contamination due to after-running effects, where material continues to flow from the cannula after the piston is relieved, and lack a controlled and reproducible suck-back mechanism.
Innovation Solution
A syringe design featuring a frictional engagement element and a spring element that couples with the piston body, allowing for controlled relative displacement and tensioning, which prevents unintentional release and enables a predetermined suck-back effect by storing energy during insertion and releasing it to retract the piston and retract material back into the syringe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional syringe is used for dispensing flowable material, then material can be delivered to the application point, but material continues to flow from the cannula after the piston is relieved causing contamination
Solution Approach 1:
The spring element is pre-loaded and stores energy during piston insertion, then automatically activates to pull the piston back after material dispensing. This preliminary energy storage and automatic counter-action prevents the after-running effect before it occurs, eliminating material leakage and contamination without requiring manual intervention.
2Productivity
If the piston is pushed in to dispense material, then material flows from the syringe, but the piston remains inserted causing material to continue flowing
Solution Approach 1:
The system transitions from a static piston position to a dynamic automatic retraction mechanism. The spring element provides dynamic motion to the piston, automatically pulling it back after dispensing. This dynamic mechanism ensures reliable control of material flow by eliminating the after-running effect, preventing both over-dispensing and contamination.
3Ease of operation
If manual relief of the piston is required to stop material flow, then material dispensing can be controlled, but additional cleaning steps and time are required
Solution Approach 1:
The spring element automatically performs the piston retraction function that would otherwise require manual intervention. The system is self-service in that it autonomously controls the dispensing process and automatically returns the piston to its initial position, eliminating the need for manual relief operations and subsequent cleaning steps, thereby saving time and improving efficiency.
4Reliability
If a frictional engagement element with spring element is added to enable automatic piston retraction, then material leakage is prevented, but device complexity increases
Solution Approach 1:
The frictional engagement element and spring element are integrated into a unified mechanism that combines friction-based piston engagement with elastic energy storage. This merged design achieves reliable automatic piston retraction and prevention of the after-running effect through a coordinated system where the spring provides force and the friction element provides controlled engagement, preventing material leakage without requiring multiple separate complex components.
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 effectively minimizes post-use leakage and contamination by ensuring a controlled and reproducible suck-back effect, maintaining a clean work environment and reducing the need for additional cleaning steps, while allowing for efficient material dispensing without manual membrane relief.
Implementation Method 1
the spring element can be tensioned when the piston and/or the piston body is inserted into the sleeve by the frictional engagement element remaining relative to the piston body, wherein relaxation of the spring element enables the piston body to be at least partially expelled from the sleeve
Implementation Method 2
a frictional engagement element and a spring element that couples with the piston body, allowing for controlled relative displacement and tensioning
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 2d
AI summary
The invention relates to a syringe (1) for the metered dispensing of materials, in particular flowable and/or pasty dental materials, comprising a sleeve (10) for receiving material and a piston (15) that can be inserted into the sleeve (10), the piston having a piston body (15'), a frictional locking element (25) which frictionally engages an inner wall (35) of the sleeve (10), and a spring element (30) coupling the frictional locking element (25) and the piston body (15'), wherein the sleeve (10) and the piston (15) inserted into the sleeve (10) define an inner chamber (70) of the sleeve for receiving the material, wherein the spring element (30) can be tensioned when the piston (15) and/or the piston body (15') is inserted into the sleeve (10) by the frictional locking element (25) remaining relatively farther away from the piston body (15').wherein a relaxation of the spring element (30) enables at least partial expulsion of the piston body (15') from the sleeve (10) with the friction element (25) remaining stationary, in order to enlarge the interior space (70) of the sleeve, and a corresponding method, a piston (15) and a friction spring element (20).