Piston Rod Centering Aid for Compact Injection Devices
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Solution Overview
Problem
Existing injection devices face challenges in achieving a compact design while ensuring reliable and homogeneous force application to the piston rod for administering liquid substances, particularly with high-viscosity products, leading to potential alignment issues and unsafe deviations.
Innovation Solution
The injection device incorporates a piston rod with a centering aid, such as a centering flange or truncated member, to guide the piston rod accurately within the product container, minimizing space requirements and ensuring uniform force distribution, even with asymmetrical cross-sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact design is implemented to reduce device size, then the space requirement is reduced, but the alignment precision and force distribution homogeneity deteriorate
Solution Approach 1:
A piston rod guide is introduced as an intermediary component between the piston rod and the product container. The guide features a guide cross-section that matches the piston rod cross-section, providing precise alignment and guiding the piston rod accurately within the product container while maintaining a compact overall device design.
Solution Approach 2:
The piston rod guide provides localized precision guidance at the critical interface between the piston rod and product container, while other parts of the device can maintain compact dimensions. This localized quality enhancement ensures homogeneous force distribution without requiring the entire device to be large.
2Volume of moving object
If a compact design is implemented to reduce device size, then the space requirement is reduced, but the force distribution homogeneity deteriorates
Solution Approach 1:
The piston rod guide acts as a mediator that ensures the piston rod is accurately positioned within the product container, thereby ensuring homogeneous force distribution on the piston throughout the injection process, even in a compact device configuration.
Solution Approach 2:
The guide cross-section is specifically designed to match the piston rod cross-section, changing the geometric parameters at the interface to ensure optimal alignment and homogeneous force distribution, preventing jamming and ensuring reliable product administration.
3Device complexity
If the piston rod cross-section is reduced to save space, then the device complexity is reduced, but the alignment stability deteriorates
Solution Approach 1:
The piston rod guide serves as a stabilizing intermediary that compensates for the reduced piston rod cross-section. The guide's matched cross-section provides the necessary alignment stability, allowing the piston rod to maintain simple, space-efficient dimensions without compromising alignment accuracy.
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
This design maintains precise alignment and homogeneous force application, preventing jamming and ensuring reliable product administration, even with high-viscosity substances, while reducing the overall device size.
Implementation Method 1
The guide cross-section is adapted or matched to the piston rod cross-section and limits movement of the piston rod cross-section in all directions perpendicular to the longitudinal axis to a manufacturing minimum
Implementation Method 2
a piston rod with a piston rod cross-section perpendicular to the longitudinal axis and a plug-side drive surface for driving the plug through force-fitting contact
Data Source
Figure 1
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AI summary
The invention relates to an injection device having reduced space requirements and having a reliable drive. Because of a plunger rod having a maximum outside diameter that is considerably less than the diameter of the product container, the plunger rod is not longitudinally guided by the product container. This is compensated by a centering aid on the plunger rod tip in the form of a centering flange or a centering stub, which centering aid counteracts inaccurate or insufficient alignment of the plunger rod in the product container.