Anti-rotation Piston Ribs for Viscous Dispenser Sealing
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Solution Overview
Problem
Existing cosmetic dispensers for viscous or semi-viscous products face challenges in preventing piston rotation during lead screw rotation, leading to increased torque requirements and potential leakage, and existing solutions either compromise aesthetics, introduce assembly complexities, or result in undesirable leakage due to interference changes over time.
Innovation Solution
A dispenser design featuring a piston with axially aligned ribs and sealing rings within a cylindrical chamber, where the ribs prevent piston rotation without significantly increasing resistance, and a threaded rod system that translates the piston as it rotates, ensuring effective sealing and smooth operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interference between the piston seal and the inner wall of the vial is increased to prevent rotation, then piston rotation is prevented, but the force needed to translate the piston increases
Solution Approach 1:
The anti-rotation feature is segmented into discrete ribs (at least two) positioned circumferentially around the piston rather than relying on uniform seal interference. This segmentation allows rotation prevention through geometric constraint while maintaining smooth contact surfaces for low-friction axial translation.
Solution Approach 2:
The ribs create an asymmetric geometric constraint that prevents rotation by engaging with corresponding features on the vial inner wall, while the sealing surfaces remain symmetric and smooth to minimize friction during axial movement.
2Reliability
If interference between the piston seal and the inner wall of the vial is increased to prevent rotation, then piston rotation is prevented, but consumer satisfaction decreases due to increased torque requirement
Solution Approach 1:
The anti-rotation function is achieved through discrete ribs rather than increased seal interference, allowing the dispenser to rotate freely during normal operation and providing a smooth user experience while still preventing piston rotation when needed.
3Reliability
If vertical flats or ribs are added to the inside of the vial to prevent rotation, then piston rotation is prevented, but product leakage occurs due to interrupted smoothness
Solution Approach 1:
The ribs are positioned locally on the piston surface to provide anti-rotation function, while the bulk of the piston and vial contact surfaces remain smooth to maintain effective sealing and prevent product leakage.
Solution Approach 2:
The ribs act as intermediary features on the piston that engage with the vial to prevent rotation, while separate sealing rings or smooth sealing surfaces maintain the liquid barrier to prevent leakage.
4Reliability
If vertical flats or ribs are added to the inside of the vial to prevent rotation, then piston rotation is prevented, but the piston seals relax over time allowing rotation
Solution Approach 1:
The anti-rotation function is achieved through discrete ribs that provide immediate geometric constraint, eliminating reliance on seal interference that relaxes over time. The ribs maintain their anti-rotation function throughout the product lifecycle.
Solution Approach 2:
Instead of relying on the seal to prevent rotation (which fails when it relaxes), the design inverts the approach by using rigid geometric constraints (ribs) to prevent rotation, making the seal's relaxation irrelevant to rotation prevention.
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 design effectively prevents piston rotation while maintaining low resistance to axial translation, ensuring consistent product dispensing without leakage and simplifying assembly, thus enhancing user satisfaction and operational reliability.
Implementation Method 1
a lead screw drives and causes the piston to translate within the vial, thereby applying pressure to the bulk product within the vial
Implementation Method 2
The piston includes a sealing ring adapted to circumferentially seal against an inner wall of the cylindrical chamber
Implementation Method 3
The ribs are disposed on a side of the piston and are seated against the inner wall of the cylindrical chamber
Data Source
AI summary
An elongate container includes a cylindrical chamber having an opening at one end of the container. A collar is affixed to the elongate container, and a threaded rod is axially disposed within the cylindrical chamber and coupled to the collar. The collar is adapted to rotate the threaded rod relative to the elongate container. A piston is disposed within the cylindrical chamber and is threadingly engaged with the threaded rod. The piston includes a sealing ring adapted to circumferentially seal against an inner wall of the cylindrical chamber and at least two axially aligned ribs. The ribs are disposed on a side of the piston and seated against the inner wall of the cylindrical chamber. With this arrangement, rotation of the threaded rod causes translation of the piston in the axial direction.