Flareless Pipe Joint Stop Ring for Sealing and Pullout Resistance
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Solution Overview
Problem
Conventional pipe joints face inefficiencies in working efficiency and quality due to the need for specialized tools for flaring, susceptibility to cracks, and reduced pipe thickness leading to hermeticity issues, especially when used as coolant pipes, where the pawl fails to bite into the pipe material causing leakage and low resistance to extraction.
Innovation Solution
A pipe joint design featuring a flare joint body with a male screw and reduced-diameter slope surface, a cap nut with a female screw and tapered sections, and a stop ring with plastically-deformable cylindrical thin parts and toothed tips that generate extraction resistance by tightly contacting the pipe's outer surface, eliminating the need for preliminary working and enhancing sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flared part is provided at the end portion of the pipe using plastic forming, then hermeticity is ensured through mutual pressure contact, but working efficiency deteriorates due to requirement of dedicated tools and preliminary working
Solution Approach 1:
The stop ring is pre-installed in the cap nut before connection, with its pawl positioned to automatically engage the pipe outer surface upon tightening. This eliminates the need for preliminary flaring work at the connection site, as the sealing and locking actions are integrated into the single tightening operation.
Solution Approach 2:
The invention extracts the sealing function from the pipe end preparation process and relocates it to the cap nut assembly. The stop ring with pawl provides the sealing action independently, eliminating the requirement for flared parts on the pipe itself, thus removing the need for dedicated flaring tools and preliminary working.
2Ease of manufacture
If a flared part is provided at the end portion of the pipe, then connection is achieved, but quality uniformity deteriorates due to difficulty in maintaining consistent flaring quality
Solution Approach 1:
The stop ring with pawl is designed to automatically adapt to the pipe outer surface during tightening. The pawl engages the pipe surface without requiring pre-formed features, allowing the connection mechanism to self-adjust and ensure consistent quality regardless of minor variations in pipe dimensions or surface conditions.
3Strength
If the pipe thickness is reduced during tightening of the cap nut, then the cap nut can be secured, but hermeticity deteriorates and loosening becomes likely
Solution Approach 1:
The stop ring acts as an intermediary component between the cap nut and the pipe. It transfers the tightening force from the cap nut to the pipe through the pawl engagement, distributing the stress and preventing excessive localized thinning of the pipe wall while maintaining secure connection and hermeticity.
4Force
If the pawl is designed to bite into the pipe outer surface, then extraction resistance is generated, but cracks may occur at the pipe edge
Solution Approach 1:
The pawl geometry is optimized with specific dimensional parameters including a rounded tip radius and controlled engagement angle. These parameter changes allow the pawl to generate sufficient extraction resistance through friction and distributed contact pressure rather than concentrated biting forces, preventing crack initiation at the pipe edge while maintaining secure connection.
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 improves working efficiency, prevents pipe extraction, and maintains excellent hermetic performance by distributing extraction resistance evenly across the back and front teeth, reducing the need for additional sealing members and tools, and enhancing resistance to bending forces.
Implementation Method 1
a tip provided with a plastically-deformable and substantially cylindrical thin part and a pipe extraction preventing tooth part formed at a tip head of the substantially cylindrical thin part
Implementation Method 2
the first tip side of the back tooth and the second tip side of the front tooth of the stop ring come into a state of tightly contacting an outer peripheral surface of a straight tip part of a connection target pipe under pressure to generate pipe extraction resistance
Data Source
Figure 1
Figure 2
Figure 3(A)~3(B)
AI summary
[Problem] To provide a pipe joint allowing reliable connection to a pipe P without flaring. [Means of solving problem] The pipe joint includes a flare joint body 1F, a cap nut 2, and a stop ring 3. A curved pressure-contacting slope surface 32 of the stop ring 3 contacts a slope surface 5 with reduced-diameter tip of the flare joint body 1F under pressure to establish sealing by means of mutual contact between metallic surfaces. The pipe P is grasped in a tightly pressure-contacting state using a back tooth and a front tooth formed at a tip head 37 of a substantially cylindrical thin part 35 of the stop ring 3.