Plastic Hose Screw Fitting With Built-In Torque Limitation
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Solution Overview
Problem
Existing screw elements for attaching plastic tubes to laboratory equipment face challenges in compactness, cost-effectiveness, and reliable torque limitation, especially in cramped spaces, leading to potential damage to the plastic threads or inadequate sealing.
Innovation Solution
A screwing element with a rotatable hand or tool part and a threaded part, featuring axially directed ramps and a spring ring for torque limitation, allowing for precise control of axial forces to prevent over-tightening and ensure secure attachment without damaging the plastic threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a screw element is tightened sufficiently to ensure secure attachment, then the sealing is improved, but the plastic threads may be damaged or the hose sealing may be compromised due to excessive torque
Solution Approach 1:
The spring ring provides continuous feedback through its elastic deformation. As torque is applied during tightening, the spring ring deforms elastically, automatically limiting the maximum torque transmitted to the plastic threads. This feedback mechanism prevents over-tightening while ensuring sufficient sealing pressure is achieved.
Solution Approach 2:
The invention changes the mechanical parameter of torque transmission by introducing a spring element with specific elastic properties. The spring ring's stiffness and pre-load are designed to allow adequate tightening force while automatically capping the maximum torque to prevent thread damage, thus optimizing the parameter range for both sealing and thread protection.
2Reliability
If existing torque limitation devices are implemented, then torque control is improved, but the device complexity and manufacturing difficulty increase due to delicate structures requiring complex injection molds
Solution Approach 1:
The torque limitation function is merged directly into the screw element's cap portion through integration of the spring ring mechanism. This eliminates the need for separate torque-limiting devices or complex multi-component assemblies, reducing overall device complexity while maintaining reliable torque control.
Solution Approach 2:
The spring ring mechanism is self-regulating and automatically limits torque based on its elastic properties without requiring external control systems or complex mechanisms. The structure serves its own torque-limiting function through its inherent elasticity, simplifying both design and manufacturing.
3Reliability
If existing torque limitation devices are used, then torque control is achieved, but the compactness is reduced as the devices are not truly compact
Solution Approach 1:
The spring ring is nested within the cap portion of the screw element, with the torque-limiting mechanism contained inside the overall screw assembly. This nested arrangement allows the torque limitation function to be achieved without increasing the external dimensions of the screw element, maintaining compactness.
4Force
If screw fittings are tightened with tools in confined spaces, then sufficient tightening force is achieved, but access to the screw fittings is difficult due to limited space
Solution Approach 1:
The spring ring acts as a disposable or single-use torque-limiting element that is integrated into the screw cap. Once the screw is tightened and the spring ring has fulfilled its torque-limiting function, the entire screw element can be easily removed and replaced if needed, bypassing the need for complex tool access in confined spaces during maintenance or adjustment.
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 provides a compact, cost-effective screwing element that reliably limits torque, preventing damage to plastic threads and ensuring proper sealing, even in tight spaces, while maintaining the necessary contact pressure to prevent material flow in PTFE or FEP lines.
Implementation Method 1
a device which limits the torque transmissible from the first part (14) to the second part (16)... comprising a spring element (24)... The spring element (24) is rotatably attached to the second part (16)... The spring element (24) is provided with spring tongues (25) which can spring in a direction parallel to the longitudinal axis (18) of the screw element (10), i.e. axially
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3A~3D
AI summary
A screwable element (10) for fastening an object, in the form of a plastic conduit for example, to a counterpiece such as a connection to another conduit or a device connection, consists of a first part (14) rotatable manually or with a tool, and a second part (16) furnished with a threaded portion (15), wherein the first and second parts are rotatable relative to one another about the longitudinal axis (18) of the screwable element, but can be fixed to one another axially via a connection point (20), and a unit (24, 26) limiting the torque that can be transmitted from the first part onto the second part. Said unit comprises at least one spring part (24) that is rotatable with the first or the second part, is resilient in a direction parallel to the longitudinal axis of the screwable element and cooperates with detents (26) of the respective other part.