Trailing Piston Support Lip for Self-Centering Cartridge Sealing
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Solution Overview
Problem
Conventional sealing and ejection pistons for cartridges face issues with centering and guiding during insertion, leading to potential damage and inadequate sealing, which can result in air ingress and unwanted flow of filling material.
Innovation Solution
A piston design featuring multiple elastic sealing lips and lamellae with self-centering and self-sealing capabilities, including a front lamella with projections and rear seals that adjust to pressure changes, ensuring proper alignment and sealing against the cartridge wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a forward-facing sealing lip is provided at the front of the piston, then the seal is reinforced as ejection pressure increases, but the sealing lip can become entangled with the rear edge of the cartridge wall during insertion and the piston can tilt and become stuck
Solution Approach 1:
The sealing function is divided into multiple independent sealing lips (front sealing lip, rear sealing lips) spaced axially along the piston. Each sealing lip operates independently to seal at different locations, preventing entanglement while maintaining sealing effectiveness. The segmentation allows the piston to insert smoothly without a single large sealing lip causing obstruction.
Solution Approach 2:
The sealing lips are arranged in the axial dimension rather than relying on a single radial sealing contact. By distributing sealing surfaces along the axial length of the piston, the design transforms a potential insertion obstruction into a progressive sealing sequence that guides the piston into the cartridge.
2Ease of manufacture
If the piston is inserted using mechanical force or compressed air, then the piston can be positioned in the cartridge, but the piston may tilt and become stuck against the cartridge wall causing damage to the sealing lip
Solution Approach 1:
Multiple sealing lips are positioned beforehand along the axial length to provide progressive contact with the cartridge wall during insertion. This distributed contact acts as a cushioning mechanism that prevents sudden tilting and reduces the risk of sealing lip damage while still allowing mechanical or pneumatic insertion forces to be applied.
3Reliability
If the piston blocks the filling material, then the filling material can be contained, but air can penetrate from the back of the cartridge between the inner wall and the sealing lip into the interior
Solution Approach 1:
The sealing function is segmented into multiple axial sealing lips that create multiple barrier zones. This segmentation prevents air from finding a single path through the sealing interface, as each sealing lip creates an independent barrier that air must penetrate through, thereby eliminating air ingress while maintaining filling material containment.
Solution Approach 2:
The design converts the potential harm of high ejection pressure (which could force air past a single seal) into a benefit by using multiple sealing lips. The pressure that might compromise a single seal instead reinforces multiple seals in series, making air ingress increasingly difficult while maintaining effective containment.
4Device complexity
If a single sealing lip design is used, then the structure is simple, but inadequate sealing can occur leading to air entry and filling material reaction with ingress air
Solution Approach 1:
The sealing system is segmented into multiple axial sealing lips rather than using a single sealing element. This segmentation provides redundant sealing zones that prevent air ingress while maintaining relative structural simplicity. Each sealing lip is a straightforward radial extension, keeping individual components simple while the multi-zone arrangement ensures adequate sealing.
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 piston effectively prevents air ingress and unwanted flow of filling material by maintaining alignment and sealing, even under pressure changes, through its elastic and self-adjusting design.
Implementation Method 1
the sealing surface bears elastically against the inside of the wall to seal between the inside of the wall of the cartridge and the piston
Implementation Method 2
designed such that it is automatically pushed outwards from the rear of the piston when air is applied
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A piston 1 has a domed piston plate 2 and a substantially cylindrical skirt 3. The skirt 3 adjoins the piston plate 2 at its rear. A gap 5 of depth t is formed between a first section 30 of the skirt 3 and the lamella 4. A rear lamella 6 adjoins the front lamella 4 at its rear. Furthermore, a second section 31 of the skirt 3 has a first seal and a second seal 82.