Needle-less Injector Sliding Membrane Friction Reduction
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Solution Overview
Problem
Existing needleless injection devices face high friction between the elastically deformable membrane and the glass reservoir, which absorbs a significant amount of energy and reduces the efficiency of the jet pressure for injecting viscous or solid active principles, necessitating lubrication during production and assembly.
Innovation Solution
A sock made of a material with a lower coefficient of friction than the membrane, enveloping the tubular part of the membrane, is used to reduce friction between the membrane and the reservoir, facilitating the sliding and elongation of the membrane under gas pressure, thereby enhancing jet pressure and reducing energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the membrane is made of elastomer material, then it provides sufficient elasticity and deformability for injection, but high friction is generated against the glass reservoir wall
Solution Approach 1:
A lubricating coating is applied to the inner surface of the glass reservoir to serve as an intermediary layer between the elastomer membrane and the glass wall. This coating reduces the coefficient of friction, allowing the membrane to expand and slide more efficiently during injection while maintaining the necessary elastic properties of the elastomer material.
Solution Approach 2:
The surface properties of the reservoir are modified by applying a lubricating coating that changes the friction parameter at the interface between the membrane and reservoir. This parameter change reduces energy loss to friction while preserving the elastomer's elastic deformation capability.
2Force
If the membrane expands axially under gas pressure, then injection force is generated, but friction with the reservoir wall absorbs a large part of the energy
Solution Approach 1:
The lubricating coating on the reservoir inner surface acts as a mediator that reduces frictional resistance during the membrane's axial expansion. This allows more of the gas-generated pressure energy to be converted into useful injection force rather than being dissipated as friction heat.
Solution Approach 2:
By changing the surface friction parameter through lubrication, the energy conversion efficiency from gas pressure to injection force is improved. The lubricated interface reduces energy losses, enabling more effective force transmission to the plunger and active ingredient.
3Loss of energy
If lubrication is applied to reduce friction, then energy loss is reduced, but an additional binding step is required during production and assembly
Solution Approach 1:
The lubricating coating is applied to the reservoir during the manufacturing process before final assembly, so that the friction-reducing property is already in place when the device is assembled. This preliminary action integrates the lubrication function into the production workflow rather than requiring a separate post-assembly step.
Solution Approach 2:
The manufacturing process is designed to incorporate surface modification (lubrication) as part of the reservoir fabrication sequence, changing the surface friction parameter during production. This integration reduces the number of discrete assembly steps while achieving the desired low-friction interface.
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 sock effectively limits friction and enhances the power of the active ingredient jet at the nozzle outlet, promoting the deployment and elongation of the membrane, resulting in improved injection efficiency without the need for lubrication during production.
Implementation Method 1
the gas pressure also deforms the membrane radially
Implementation Method 2
an elastically deformable membrane of generally T-shaped, which comprises a radial annular disc and a part tubular which extends axially into the tank
Implementation Method 3
the friction between the membrane, which is generally made of elastomer, and the glass wall of the tank, is high and absorbs a large part of the energy
Data Source
Figure 1
Figure 2~4
AI summary
The invention relates to a needle-less injector device (10) comprising a member (12) that forms a housing (44), a gas generator (16), a tubular reservoir (24) that contains an active substance (26) to be injected, a flexible, substantially T-shaped membrane (50) which includes a tubular portion (54) that extends axially inside the reservoir (24) and is designed to be extended axially in the reservoir (24) under the effect of the pressure generated by the gas generator (16), and a nozzle (38) for injecting the active substance (26), said nozzle (38) being located at the lower end of the reservoir (24), the device (10) being characterized in that it comprises a jacket (64) which at least partially surrounds the tubular portion (54) of the membrane and which is suitable for limiting the friction between the tubular portion (54) of the membrane (50) and the reservoir (24).