Piston Ring Joint Geometry for Low-Leakage Dynamic Sealing
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Solution Overview
Problem
Conventional piston rings experience leakage and pressure loss due to incomplete sealing and increased wear, especially in hydraulic and pneumatic applications, as the ring gap does not close completely, leading to suboptimal sealing performance.
Innovation Solution
A rotationally symmetric piston ring design with a ring body and ring joint, featuring an inclined ring surface that expands dynamically to enhance sealing, and a projection and base section with inverse inclination separating surfaces, ensuring precise alignment and self-centering, which maintains sealing even with wear and thermal changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the ring gap does not close completely to compensate for thermal elongations, then thermal expansion is accommodated, but leakage and pressure loss occur
Solution Approach 1:
The piston ring incorporates a dynamic expansion mechanism where the ring body can expand radially outward through an inclined expansion surface. This allows the ring to adapt its shape dynamically based on operating conditions, enabling the ring gap to close or remain open as needed while maintaining sealing contact with the cylinder wall, thus resolving the contradiction between thermal expansion compensation and pressure loss prevention
2Loss of energy
If the ring gap is reduced by overlapping piston ring ends, then pressure loss is reduced, but sealing effect becomes insufficient and leakage increases with wear
Solution Approach 1:
The invention employs asymmetric geometry at the ring joint with a projection section on one ring body end and a corresponding recess on the other end. This asymmetric design creates an interference fit that provides both initial sealing contact and allows for dynamic adjustment during operation, maintaining sealing effectiveness while accommodating wear and thermal changes without requiring complete gap closure
3Reliability
If pretension force is increased to improve sealing, then sealing effect improves, but wear on the radial ring surface increases
Solution Approach 1:
The piston ring uses a dynamic expansion mechanism where the ring body expands radially through an inclined expansion surface when pressure differential acts across the ring. This allows the ring to achieve high sealing contact pressure only when needed (under pressure differential), while maintaining lower contact pressure during normal operation, thus improving sealing without proportionally increasing wear
Solution Approach 2:
The invention changes the contact pressure parameter dynamically based on operating conditions. The expansion mechanism allows the ring to transition from a lower contact pressure state during normal operation to a higher contact pressure state when sealing is critical, optimizing the balance between sealing effectiveness and wear reduction
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 design achieves almost complete sealing against fluid and gaseous pressure media, reducing wear and maintaining tightness across various conditions, including thermal expansion and contraction, while allowing for radial and circumferential expansion, thus providing a high and consistent sealing effect.
Implementation Method 1
the wedge effect on the inclined ring surface leads to a radial expansion of the piston ring and to a force effect on the surface pressure between the radial ring surface and the inner barrel surface of the cylinder
Implementation Method 2
the surface pressure is reduced to the surface pressure based on the spring effect during a return movement of the piston without working pressure and, thus, wear is reduced
Implementation Method 3
Since the ring gap does not close completely in the installed condition to compensate for thermal elongations
Data Source
AI summary
A piston ring includes a ring body with a first body end and a second body end arranged opposite one another to define a ring joint. The body has a radial ring surface axially displaceable relative to an inner barrel surface and an inclined ring surface that rests on an inclined ring groove surface. The first body end has a projection section with a projection section separating surface. The second body end has a base section with a receiving contour, a base section separating surface and a base section contour. The projection section separating surfaces and the base section separating surface are in sealing physical contact and define a plane. The plane intersects the inclined ring surface and defines an inner separating line at a second intersection line of the plane with the inclined ring surface.