Adaptive Piston Ring Geometry for Bent-Axis Sealing
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Solution Overview
Problem
Radial piston machines face issues with size, weight, and manufacturing costs due to the use of bent-axis pistons, which introduce increased friction, sealing problems, and excessive stresses on piston rings, leading to reduced efficiency and lifespan.
Innovation Solution
A piston ring with orthogonal axes, where the body portion is resiliently deformable in one direction and rigid in the other, allowing it to change between elliptical and circular shapes, featuring gaps and biasing elements to maintain a consistent seal and reduce stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If bent-axis pistons are used to reduce machine size, then the machine becomes more compact, but friction between piston and piston cylinder increases
Solution Approach 1:
The piston ring is designed with dynamic deformation capability, allowing it to change shape between circular and elliptical forms as the piston moves. This dynamic adaptation enables the ring to maintain optimal contact with the piston surface throughout the motion cycle, reducing friction while accommodating the bent-axis piston geometry
Solution Approach 2:
The piston ring's physical parameters (shape, cross-sectional area, thickness) are varied along its circumference and through its structure. The cross-sectional area is specifically designed to be larger at the ends than in the middle, creating a cambered profile that optimizes contact pressure distribution and reduces friction during piston movement
2Volume of moving object
If bent-axis pistons are used to reduce machine size, then the machine becomes more compact, but sealing performance deteriorates
Solution Approach 1:
The piston ring dynamically changes its cross-sectional area during operation, being compressed more at the ends than in the middle. This creates a cambered shape that ensures continuous contact with the piston surface, maintaining effective sealing despite the piston's angular movement in bent-axis configuration
Solution Approach 2:
Different portions of the piston ring have different cross-sectional areas, with the ends having larger areas than the middle section. This local variation in geometry creates optimal contact pressure distribution, ensuring reliable sealing at the critical end regions while accommodating the bent-axis piston motion
3Volume of moving object
If bent-axis pistons are used to reduce machine size, then the machine becomes more compact, but stresses on piston rings increase
Solution Approach 1:
The piston ring's cross-sectional area is optimized to be larger at the ends than in the middle, creating a cambered profile that distributes mechanical stresses more evenly. This geometric parameter variation reduces stress concentration at critical points, allowing the ring to withstand the high stresses generated by bent-axis piston operation
Solution Approach 2:
The piston ring is designed as a resilient, flexible component that can deform elastically under load. This flexibility allows the ring to absorb and distribute stresses generated by the bent-axis piston motion, preventing stress concentration and reducing the risk of fatigue failure
4Reliability
If piston rings are made rigid to maintain seal, then sealing line perpendicularity is maintained, but the ring cannot adapt to elliptical deflections
Solution Approach 1:
The piston ring has non-uniform cross-sectional area, with larger areas at the ends and smaller area in the middle. This local variation provides different stiffness characteristics at different locations, allowing the ring to maintain perpendicular sealing at the ends while permitting controlled elliptical deflection in the middle section
Solution Approach 2:
The piston ring is designed with controlled flexibility, allowing it to dynamically adjust its shape during operation. The ring can maintain a perpendicular sealing line at the contact surfaces while simultaneously adapting its overall form to elliptical deflections caused by bent-axis piston motion
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 piston ring reduces friction and leakage, increases machine efficiency and lifespan, and facilitates the design of smaller, lighter radial piston machines by minimizing stress and maintaining a consistent sealing performance.
Implementation Method 1
a body portion which is resiliently deformable in the direction of said first axis and is substantially rigid in the direction of the second axis
Data Source
AI summary
A piston ring (10) for forming a seal between a piston (26) and piston housing (28). The piston ring (10) has first and second orthogonal axes (12, 14) and a body portion (18) which is resiliently deformable in the direction of the first axis (12) and is substantially rigid in the direction of the second axis (14).