Sealing Device Back-Up Ring Insertion Deformation
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Solution Overview
Problem
The existing high-pressure sealing devices with triangular cross-sectional back-up rings face issues during insertion due to diameter expansion, leading to potential damage and interference with the shaft hole, as the second back-up ring compresses the first back-up ring, causing its outer diameter to expand and interfere with the shaft hole.
Innovation Solution
A sealing device with a first back-up ring having a concave circular inclined surface and a second back-up ring with a convex circular inclined surface, where the inner diameter of the first back-up ring is larger than the contact surface of the second back-up ring, preventing the second back-up ring from moving towards the mounting groove and thus avoiding deformation of the first back-up ring during insertion, and allowing elastic expansion under pressure for effective sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second back-up ring has an inclined surface portion with acute angle, then the back-up ring can be compact and easy to manufacture, but the outer diameter of the first back-up ring expands during insertion causing interference with the shaft hole
Solution Approach 1:
The contact surface portion is designed to preemptively counteract the compression force during insertion. By providing a flat contact surface that contacts the mounting groove side surface before the inclined surface portions engage, the structure prevents the harmful diameter expansion from occurring in the first place, rather than compensating for it afterward.
Solution Approach 2:
The back-up ring structure is segmented into distinct functional zones: a flat contact surface portion for preventing axial movement and diameter expansion, and inclined surface portions for providing sealing contact. This segmentation allows each portion to perform its specific function without interfering with the other, resolving the contradiction between compact design and insertion problems.
2Reliability
If the back-up ring is compressed during insertion to ensure sealing contact, then sealing performance is improved, but the outer diameter expands and interferes with the shaft hole opening
Solution Approach 1:
The flat contact surface portion acts in advance to prevent the axial compression that would lead to radial expansion. By establishing contact with the mounting groove side surface first, it counteracts the insertion force before it can transmit to the inclined surface portions and cause diameter expansion.
Solution Approach 2:
Different portions of the back-up ring have different geometric properties optimized for their specific functions: the contact surface portion is flat to prevent axial movement, while the inclined surface portions are angled to provide sealing contact. This local differentiation allows sealing performance without harmful expansion.
3Volume of moving object
If the inclined surface portion has an acute angle for compact design, then the device is more compact, but the corner gets compressed causing the first back-up ring to deform and expand in diameter
Solution Approach 1:
The back-up ring is divided into a contact surface portion and inclined surface portions with distinct functions. The contact surface portion maintains a stable flat geometry for preventing deformation, while the inclined surface portions can have acute angles for compactness without compromising the overall shape stability.
Solution Approach 2:
The contact surface portion preemptively counteracts the compression forces that would deform the inclined surface portions. By providing a stable base that contacts the mounting groove first, it prevents the acute-angled corners from being compressed during insertion.
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 configuration suppresses the diameter expansion of the first back-up ring during insertion, preventing damage and ensuring effective sealing by allowing the first back-up ring to elastically expand radially and maintain contact with the housing, enhancing the sealing performance.
Implementation Method 1
the seal ring 11 made of a rubbery elastic body
Implementation Method 2
the first back-up ring 21 is placed on the opposing sealing fluid side (the low-pressure side L) of the seal ring 11, and therefore, it is possible to prevent the seal ring 11 from protruding into a gap 54
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention is intended to suppress the diameter expansion of a first back-up ring when inserted, thereby suppressing the damage on the first back-up ring in a sealing device composed of a combination of a seal ring mounted in a mounting groove with a rectangular cross-section, the first back-up ring, and a second back-up ring. To achieve this object, the first back-up ring has a shape having an end surface portion in contact with an opposing-sealing-fluid-side side surface portion of the mounting groove, a peripheral surface portion, and an inclined surface portion. The second back-up ring has a shape having an end surface portion in contact with the seal ring, a peripheral surface portion facing a bottom surface portion of the mounting groove, and an inclined surface portion. A contact surface portion that is a plane perpendicular to the axis in contact with the opposing-sealing-fluid-side side surface portion of the mounting groove is provided in an inner peripheral end of the inclined surface portion of the second back-up ring. The inner diameter of the first back-up ring is set to be larger than the outer diameter of the contact surface portion of the second back-up ring, and the outer diameter of the first back-up ring is set to be smaller than the inner diameter of a housing.